@article{jiang_araia_balyan_robinson_brown_caiola_hu_dou_neal_li_2024, title={Kinetic study of Ni-M/CNT catalyst in methane decomposition under microwave irradiation}, volume={340}, ISSN={["1873-3883"]}, DOI={10.1016/j.apcatb.2023.123255}, abstractNote={Methane catalytic decomposition has been studied with catalysts that can attenuate the energy of electromagnetic waves to heat and drive the reaction. Herein, we report, for the first time, a comprehensive kinetic study of Ni-M (M=Pd, Cu, or Fe)-CNT catalysts under microwave irradiation. These binary metal alloy nanoparticles have been synthesized on multiwalled carbon nanotube support with solvothermal process. These catalysts showed incredible performance for both absorbing microwave energy and catalyzing the reaction to form carbon nanotubes and hydrogen. Ni-M-CNT has a reaction order of 0.74. 10Ni-1 Pd-CNT, 10Ni-1Cu-CNT, and 10Ni-1Fe-CNT have activation energies at 87, 75, and 69 kJ/mol. The investigation was carried out in a differential reactor. The results indicated that 10Ni-1Fe-CNT had the lowest activation energy due to the increase in microwave susceptibility. This work pioneered the microwave catalytic methane decomposition field as well as paving the way for future electrification of COx-free hydrogen production.}, journal={APPLIED CATALYSIS B-ENVIRONMENT AND ENERGY}, author={Jiang, Changle and Araia, Alazar and Balyan, Sonit and Robinson, Brandon and Brown, Siobhan and Caiola, Ashley and Hu, Jianli and Dou, Jian and Neal, Luke M. and Li, Fanxing}, year={2024}, month={Jan} }
 @article{cai_krzystowczyk_braunberger_li_neal_2024, title={Techno-economic analysis of chemical looping air separation using a perovskite oxide sorbent}, volume={132}, ISSN={["1878-0148"]}, DOI={10.1016/j.ijggc.2024.104070}, abstractNote={Air separation is a costly process that is difficult to operate efficiently at small scales. Chemical looping air separation (CLAS) is a promising process for small-footprint oxygen production with low energy consumption. CLAS has potential applications in a promising carbon capture technology, oxyfuel combustion (oxy-combustion). In oxy-combustion, high-concentration oxygen from an air separation unit is used to combust a carbonaceous fuel into an easily-separated, nitrogen-free exhaust stream. In this paper, a techno-economic analysis was conducted in conjunction with reactor modeling to determine the cost of oxygen from a CLAS plant as a modular air separation unit for a 5 MW thermal coal-based oxy-combustion plant. The effects of different length-to-diameter ratios were investigated. The cost of oxygen from CLAS was projected to be as low as $65/ton O2 under baseline assumptions, which was much lower than typical current delivered oxygen at similar scales. Although higher in capital cost, CLAS also compares favorably to pressure swing adsorption, which has much larger parasitic energy losses. Further analysis indicates that air and steam demand and the sorbent reactor L/D ratio are key to optimizing the costs.}, journal={INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL}, author={Cai, Runxia and Krzystowczyk, Emily and Braunberger, Beau and Li, Fanxing and Neal, Luke}, year={2024}, month={Feb} }
 @article{haribal_iftikhar_tong_rayer_sanderson_li_neal_2024, title={Technoeconomic and Emissions Analysis of the Hybrid Redox Process for the Production of Acetic Acid with CO<sub>2</sub> Utilization}, volume={3}, ISSN={["2366-7486"]}, DOI={10.1002/adsu.202300453}, abstractNote={Abstract The production of oxygenated hydrocarbons, such as acetic acid, using captured CO 2 is a promising pathway to reduce greenhouse gas emissions in the chemical industry. The use of a chemical looping‐based hybrid redox process (HRP) is proposed to convert CO 2 and natural gas into separate CO and syngas streams that can be used to produce various commodity oxygenates, while allowing the beneficial utilization of captured CO 2 . Here, a detailed technoeconomic analysis of HRP applied to the production of acetic acid is presented. Emissions and energy analyses show the ability of HRP to lower the CO 2 emissions for acetic acid synthesis by 74% compared to a conventional steam and autothermal reforming route. HRP also offers a potential 34% reduction in capital costs. Compared to a dry reforming based acetic acid production route, HRP has the potential for significantly lower costs. If integrated with a low carbon energy source, HRP has the potential to achieve a negative emission of greenhouse gas (‐0.50 kg CO 2 per kg acetic acid).}, journal={ADVANCED SUSTAINABLE SYSTEMS}, author={Haribal, Vasudev and Iftikhar, Sherafghan and Tong, Andrew and Rayer, Aravind and Sanderson, Corry and Li, Fanxing and Neal, Luke}, year={2024}, month={Mar} }
 @article{song_lin_fang_li_zhao_chen_huang_he_zhao_huang_et al._2024, title={Unraveling the atomic interdiffusion mechanism of NiFe<sub>2</sub>O<sub>4</sub> oxygen carriers during chemical looping CO<sub>2</sub> conversion}, volume={2}, ISSN={["2637-9368"]}, DOI={10.1002/cey2.493}, abstractNote={By employing metal oxides as oxygen carriers, chemical looping demonstrates its effectiveness in transferring oxygen between reduction and oxidation environments to partially oxidize fuels into syngas and convert CO2 into CO. Generally, NiFe2O4 oxygen carriers have demonstrated remarkable efficiency in chemical looping CO2 conversion. Nevertheless, the intricate process of atomic migration and evolution within the internal structure of bimetallic oxygen carriers during continuous high‐temperature redox cycling remains unclear. Consequently, the lack of a fundamental understanding of the complex ionic migration and oxygen transfer associated with energy conversion processes hampers the design of high‐performance oxygen carriers. Thus, in this study, we employed in situ characterization techniques and theoretical calculations to investigate the ion migration behavior and structural evolution in the bulk of NiFe2O4 oxygen carriers during H2 reduction and CO2/lab air oxidation cycles. We discovered that during the H2 reduction step, lattice oxygen rapidly migrates to vacancy layers to replenish consumed active oxygen species, while Ni leaches from the material and migrates to the surface. During the CO2 splitting step, Ni migrates toward the core of the bimetallic oxygen carrier, forming Fe–Ni alloys. During the air oxidation step, Fe–Ni migrates outward, creating a hollow structure owing to the Kirkendall effect triggered by the swift transfer of lattice oxygen. The metal atom migration paths depend on the oxygen transfer rates. These discoveries highlight the significance of regulating the release–recovery rate of lattice oxygen to uphold the structures and reactivity of oxygen carriers. This work offers a comprehensive understanding of the oxidation/reduction‐driven atomic interdiffusion behavior of bimetallic oxygen carriers.}, journal={CARBON ENERGY}, author={Song, Da and Lin, Yan and Fang, Shiwen and Li, Yang and Zhao, Kun and Chen, Xinfei and Huang, Zhen and He, Fang and Zhao, Zengli and Huang, Hongyu and et al.}, year={2024}, month={Feb} }
 @article{cai_bektas_wang_mcclintock_teague_yang_li_2023, title={Accelerated Perovskite Oxide Development for Thermochemical Energy Storage by a High-Throughput Combinatorial Approach}, volume={3}, ISSN={["1614-6840"]}, url={https://doi.org/10.1002/aenm.202203833}, DOI={10.1002/aenm.202203833}, abstractNote={The structural and compositional flexibility of perovskite oxides and their complex yet tunable redox properties offer unique optimization opportunities for thermochemical energy storage (TCES). To improve the relatively inefficient and empirical‐based approaches, a high‐throughput combinatorial approach for accelerated development and optimization of perovskite oxides for TCES is reported here. Specifically, thermodynamic‐based screening criteria are applied to the high‐throughput density functional theory (DFT) simulation results of over 2000 A/B‐site doped SrFeO3−δ. 61 promising TCES candidates are selected based on the DFT prediction. Of these, 45 materials with pure perovskite phases are thoroughly evaluated. The experimental results support the effectiveness of the high‐throughput approach in determining both the oxygen capacity and the oxidation enthalpy of the perovskite oxides. Many of the screened materials exhibit promising performance under practical operating conditions: Sr0.875Ba0.125FeO3−δ exhibits a chemical energy storage density of 85 kJ kgABO3−1 under an isobaric condition (with air) between 400 and 800 °C whereas Sr0.125Ca0.875Fe0.25Mn0.75O3−δ demonstrates an energy density of 157 kJ kgABO3−1 between 400 °C/0.2 atm O2 and 1100 °C/0.01 atm O2. An improved set of optimization criteria is also developed, based on a combination of DFT and experimental results, to improve the effectiveness for accelerated development of redox‐active perovskite oxides.}, journal={ADVANCED ENERGY MATERIALS}, author={Cai, Runxia and Bektas, Hilal and Wang, Xijun and McClintock, Kyle and Teague, Lauren and Yang, Kunran and Li, Fanxing}, year={2023}, month={Mar} }
 @article{jasper_shahbazi_schimmel_li_wang_2023, title={Aspen Plus simulation of Chemical Looping Combustion of syngas and methane in fluidized beds}, url={https://doi.org/10.1007/s43938-023-00020-x}, DOI={10.1007/s43938-023-00020-x}, abstractNote={Abstract Chemical Looping Combustion (CLC) is a technology that efficiently combines power generation and CO 2 capture. In CLC, the fuel is oxidized by a metal oxide called an oxygen carrier (OC). CLC uses two reactors: a fuel reactor and an air reactor. The fuel reactor oxidizes the fuel and reduces the OC. The air reactor oxidizes the OC using air and then the OC is cycled back to the fuel reactor. It is typical for both the fuel and the air reactors to be fluidized beds (FBs). In this research, an Aspen Plus model was developed to simulate a CLC system. Aspen Plus has recently included a built-in FB unit operation module. To our knowledge, no literature has been reported using this FB module for simulating fluidized bed combustion or gasification. This FB unit process was investigated in Aspen Plus and a kinetic based model was used and compared the simulation results to experimental data and the commonly used Gibbs equilibrium model. The FB unit and the kinetic model well fit the experimental data for syngas and methane combustion within 2% of the molar composition of syngas combustion and within 4% for the methane combustion. An advantage of this model over other kinetic models in literature is that the core shrinking model kinetic rate equations have been converted into a power law form. This allows Aspen Plus to use a calculator instead of an external Fortran compiler. This greatly simplifies the modeling process. The reaction rate equations are given for all reactions. A sensitivity analysis of the reaction kinetics was conducted. All data, code, and simulation files are given.}, journal={Discover Chemical Engineering}, author={Jasper, Micah and Shahbazi, Abolghasem and Schimmel, Keith and Li, Fanxing and Wang, Lijun}, year={2023}, month={Feb} }
 @article{tian_benedict_li_yang_maiti_wang_fushimi_2023, title={Carbon-Assisted, Continuous Syngas Production in a Chemical Looping Scheme}, volume={8}, ISSN={["1572-9028"]}, DOI={10.1007/s11244-023-01840-5}, abstractNote={In the current energy and environment scenario, it is imperative to develop energy efficient routes for chemical manufacturing that also pave the way for mitigation of greenhouse gas emissions. This work presents an efficient pathway for continuous syngas production via a chemical looping conversion of the two most potent greenhouse gases—CH4, and CO2. The well-known dry-reforming process of converting CH4, and CO2 to syngas is energy-intensive and suffers from catalyst deactivation. The chemical looping approach, on the other hand, provides avenues for mitigating catalyst deactivation and enabling improved energy efficiency. The key to such process enhancements lies in the intricate structure–function relationships of the catalyst and its correlation to the process variables. We present the reduction and oxidation characteristics of 5 wt.% Ni/Ce1−xZrxO2-based catalysts (x = 0, 0.4, and 0.625). We demonstrate low temperature CH4 activation over Ni-promoted samples as opposed to pure Ce1−xZrxO2. Moreover, our results depict an optimum regeneration of these catalysts when oxidized by CO2, and H2O, which allows for chemical looping operation of steam reforming of methane as well. Process variables were tuned to optimize the CH4 conversion (over 80%), and H2/CO ratio at 650 °C. The critical surface reactions—carbon accumulation and gasification, and thermocatalytic CO2 splitting were investigated to elucidate the dynamic nature of the catalyst surface. The impact of this work lies in showcasing the opportunities to design chemical looping reactors for energy efficient syngas production from waste greenhouse gases.}, journal={TOPICS IN CATALYSIS}, author={Tian, Yuan and Benedict, Zoe and Li, Fanxing and Yang, Yingchao and Maiti, Debtanu and Wang, Yixiao and Fushimi, Rebecca}, year={2023}, month={Aug} }
 @article{ruan_akutsu_yang_zayan_dou_liu_bose_brody_lamb_li_2023, title={Hydrogenation of bio-oil-derived oxygenates at ambient conditions via a two-step redox cycle}, volume={4}, ISSN={["2666-3864"]}, url={https://doi.org/10.1016/j.xcrp.2023.101506}, DOI={10.1016/j.xcrp.2023.101506}, abstractNote={A key challenge in upgrading bio-oils to renewable fuels and chemicals resides in developing effective and versatile hydrogenation systems. Herein, a two-step solar thermochemical hydrogenation process that sources hydrogen directly from water and concentrated solar radiation for furfural upgrading is reported. High catalytic performance is achieved at room temperature and atmospheric pressure, with up to two-orders-of-magnitude-higher hydrogen utilization efficiency compared with state-of-the-art catalytic hydrogenation. A metal or reduced metal oxide provides the active sites for furfural adsorption and water dissociation. The in situ-generated reactive hydrogen atoms hydrogenate furfural and biomass-derived oxygenates, eliminating the barriers to hydrogen dissolution and the subsequent dissociation at the catalyst surface. Hydrogenation selectivity can be conveniently mediated by solvents with different polarity and metal/reduced metal oxide catalysts with varying oxophilicity. This work provides an efficient and versatile strategy for bio-oil upgrading and a promising pathway for renewable energy storage.}, number={7}, journal={CELL REPORTS PHYSICAL SCIENCE}, author={Ruan, Chongyan and Akutsu, Ryota and Yang, Kunran and Zayan, Noha M. and Dou, Jian and Liu, Junchen and Bose, Arnab and Brody, Leo and Lamb, H. Henry and Li, Fanxing}, year={2023}, month={Jul} }
 @article{rahmanian_pirzada_barbieri_iftikhar_li_khan_2023, title={Mechanically robust, thermally insulating and photo-responsive aerogels designed from sol-gel electrospun PVP-TiO2 nanofibers}, volume={32}, ISSN={["2352-9407"]}, url={https://doi.org/10.1016/j.apmt.2023.101784}, DOI={10.1016/j.apmt.2023.101784}, abstractNote={We present a robust approach for fabricating polyvinylpyrrolidone (PVP)-titania (TiO2) nanofibrous aerogels (NFA) with multifunctional and triggered performances. These low density (∼ 10 mg cm−3) 3D self-supported aerogels having an intrinsically lamellar porous structure (> 99% porosity) are created via solid templating of sol-gel electrospun PVP-TiO2 hybrid nanofibers. The photocatalytic activity of TiO2 allows for on-demand application wherein the aerogel exhibits antibacterial properties upon UV exposure to bacteria such as Escherichia coli and Salmonella enterica. Significantly, while the aerogel sorbs common volatile organic components (VOCs) or oil due to its innate porosity, exposure of the aerogel to ultraviolet (UV) radiation leads to their decomposition. The PVP-TiO2 NFA exhibits a low thermal conductivity (0.062 W m−1 K−1) together with considerable mechanical flexibility up to strains of 50% with >90% recovery, without the need for post-processing. The photo-responsive attributes combined with mechanical resilience, oleophilicity and thermal insulation properties render these aerogels viable candidates for a diverse range of applications. We discuss such property enhancements in terms of the interaction between PVP and TiO2 and aerogel microstructure.}, journal={APPLIED MATERIALS TODAY}, author={Rahmanian, Vahid and Pirzada, Tahira and Barbieri, Eduardo and Iftikhar, Sherafghan and Li, Fanxing and Khan, Saad A.}, year={2023}, month={Jun} }
 @article{cai_brody_tian_neal_bose_li_2023, title={Numerical modeling of chemical looping oxidative dehydrogenation of ethane in parallel packed beds}, volume={469}, ISSN={["1873-3212"]}, url={https://doi.org/10.1016/j.cej.2023.143930}, DOI={10.1016/j.cej.2023.143930}, abstractNote={Chemical looping oxidative dehydrogenation (CL-ODH) of ethane has the potential to be a highly efficient alternative to steam cracking for ethylene production. Accurate reactor modeling is of critical importance to efficiently scale up and optimize this new technology. This study reports a one-dimensional, heterogeneous packed bed model to simulate the CL-ODH of ethane to ethylene with a Na2MoO4-promoted CaTi0.1Mn0.9O3 redox catalyst. The overall reaction kinetics was well-described by coupling the gas-phase steam cracking of ethane with the reduction kinetics of the redox catalyst by H2 and C2H4. The impact of H2 on the formation rate of CO2 byproduct from C2H4 conversion was also thoroughly investigated to validate the applicability of the kinetic model under operational environments. The temperature variation within the different CL-ODH steps and the temperature distribution along the bed were also carefully considered. The accuracy of the model was validated by experiments conducted in a large lab-scale packed bed reactor (200 g catalyst loading), with an average deviation of 2.8% in terms of ethane conversion and ethylene yield. The model was subsequently used to optimize the operating parameters of the CL-ODH reactor, indicating that up to 63.7% single-pass C2 + olefin yield can be achieved with the current redox catalyst bed whereas further optimization of the redox catalyst to inhibit C2H4 activation can result in 69.4% single-pass C2 + yield while maintaining low CO2 selectivity.}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Cai, Runxia and Brody, Leo and Tian, Yuan and Neal, Luke and Bose, Arnab and Li, Fanxing}, year={2023}, month={Aug} }
 @article{zhu_chen_somayaji_novello_chacko_li_liu_2023, title={One-Step Synthesis of a High Entropy Oxide-Supported Rhodium Catalyst for Highly Selective CO Production in CO2 Hydrogenation}, volume={15}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.3c02829}, DOI={10.1021/acsami.3c02829}, abstractNote={High entropy oxide (HEO) has shown to be a new type of catalyst support with tunable composition-function properties for many chemical reactions. However, the preparation of a metal nanoparticle catalyst supported on a metal oxide support is time-consuming and takes multiple complicated steps. Herein, we used a one-step glycine-nitrate-based combustion method to synthesize highly dispersed rhodium nanoparticles on a high surface area HEO. This catalyst showed high selectivity to produce CO in CO2 hydrogenation with 80% higher activity compared to rhodium nanoparticle-based catalysts. We also studied the effect of different metal elements in HEO and demonstrated that high CO selectivity was achieved if one of the metals in the metal oxide support favored CO production. We identified that copper and zinc were responsible for the observed high CO selectivity due to their low *CO binding strength. During hydrogenation, a strong metal-support interaction was created through charge transfer and formed an encapsulated structure between rhodium nanoparticles and the HEO support to lower the *CO binding strength, which enabled high CO selectivity in the reaction. By combining different metal oxides into HEO as a catalyst support, high activity and high selectivity can be achieved at the same time in the CO2 hydrogenation reaction.}, number={26}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Zhu, Siyuan and Chen, Yufeng and Somayaji, Vasishta and Novello, Peter and Chacko, Dennis and Li, Fanxing and Liu, Jie}, year={2023}, month={Jun}, pages={31384–31392} }
 @article{brody_rukh_cai_bosari_schomaecker_li_2023, title={Sorption-enhanced steam reforming of toluene using multifunctional perovskite phase transition sorbents in a chemical looping scheme}, volume={5}, ISSN={["2515-7655"]}, url={https://doi.org/10.1088/2515-7655/acdbe9}, DOI={10.1088/2515-7655/acdbe9}, abstractNote={Sorption-enhanced steam reforming (SESR) of toluene (SESRT) using catalytic CO2 sorbents is a promising route to convert the aromatic tar byproducts formed in lignocellulosic biomass gasification into hydrogen (H2) or H2-rich syngas. Commonly used sorbents such as CaO are effective in capturing CO2 initially but are prone to lose their sorption capacity over repeated cycles due to sintering at high temperatures. Herein, we present a demonstration of SESRT using A- and B-site doped Sr1−x A’ x Fe1−y B’ y O3−δ (A’ = Ba, Ca; B’ = Co) perovskites in a chemical looping scheme. We found that surface impregnation of 5–10 mol% Ni on the perovskite was effective in improving toluene conversion. However, upon cycling, the impregnated Ni tends to migrate into the bulk and lose activity. This prompted the adoption of a dual bed configuration using a pre-bed of NiO/γ–Al2O3 catalyst upstream of the sorbent. A comparison is made between isothermal operation and a more traditional temperature-swing mode, where for the latter, an average sorption capacity of ∼38% was witnessed over five SESR cycles with H2-rich product syngas evidenced by a ratio of H2: CO x > 4.0. XRD analysis of fresh and cycled samples of Sr0.25Ba0.75Fe0.375Co0.625O3-δ reveal that this material is an effective phase transition sorbent—capable of cyclically capturing and releasing CO2 without irreversible phase changes occurring.}, number={3}, journal={JOURNAL OF PHYSICS-ENERGY}, author={Brody, Leo and Rukh, Mahe and Cai, Runxia and Bosari, Azin Saberi and Schomaecker, Reinhard and Li, Fanxing}, year={2023}, month={Jul} }
 @article{mishra_dudek_gaffney_ding_li_2023, title={Spinel oxides as coke-resistant supports for NiO-based oxygen carriers in chemical looping combustion of methane}, volume={424}, ISSN={["1873-4308"]}, url={https://doi.org/10.1016/j.cattod.2019.09.010}, DOI={10.1016/j.cattod.2019.09.010}, abstractNote={Due to their high activity for methane conversion under a cyclic redox scheme, supported nickel oxides are among the most extensively investigated oxygen carrier materials for chemical looping combustion (CLC) and reforming (CLR) of methane. However, coke formation remains as a key challenge for Ni-containing oxygen carriers. The current study investigates the effect of reducible, spinel-structured supports to enhance coke resistance of NiO-based oxygen carriers. It was hypothesized that reducible supports capable of continued yet slow lattice oxygen donation in the presence of methane can actively retard coke formation on the surface of the oxygen carriers. To evaluate such effects, NiFe2O4, MgFe2O4, and BaFe2O4 are investigated as coke-resistant, reducible supports for NiO using mass spectrometry (MS) and thermogravimetric analysis (TGA) during chemical looping cycles. All three reducible supports were capable of continuous oxygen donation over an extended period of time (>40 min) without signs of coke formation. When used as supports for NiO, the resulting oxygen carriers showed no sign of carbon deposition under typical methane CLC environments. In comparison, NiO supported on inert MgAl2O4 exhibited significant coke formation after only 2.5 min. Moreover, NiO supported on NiFe2O4 and BaFe2O4 exhibited faster redox activity and higher oxygen carrying capacity when compared to the inert MgAl2O4-supported NiO. Detailed investigation of the reduction behavior of NiFe2O4-supported NiO revealed extensive solid-state reactions and Ni/Fe exchanges among the support, NiO, and newly formed phases. Specifically, initial weight loss in NiFe2O4-supported NiO was associated with reduction of the oxygen carrier to metallic Ni and Fe3O4 phases. Subsequent coke inhibition was attributed to the slow reduction of Fe3O4 and FeO phases. Multi-cyclic redox studies indicated that NiFe2O4-supported NiO gradually lost its redox activity. In comparison, both MgFe2O4- and BaFe2O4-supported NiO exhibited satisfactory redox stability, activity, and coke resistance.}, journal={CATALYSIS TODAY}, publisher={Elsevier BV}, author={Mishra, Amit and Dudek, Ryan and Gaffney, Anne and Ding, Dong and Li, Fanxing}, year={2023}, month={Dec} }
 @article{yuan_yang_grazon_wang_vallan_isasa_resende_li_brochon_remita_et al._2023, title={Tuning the Aggregates of Thiophene-based Trimers by Methyl Side-chain Engineering for Photocatalytic Hydrogen Evolution}, volume={12}, ISSN={["1521-3773"]}, DOI={10.1002/anie.202315333}, abstractNote={Organic π-conjugated semiconductors (OCSs) have recently emerged as a promising alternative to traditional inorganic materials for photocatalysis. However, the aggregation of OCSs in photocatalytic aqueous solution caused by self-assembly, which closely relates to the photocatalytic activity, has not yet been studied. Here, the relationship between the aggregation of 4,7-Bis(thiophen-2-yl) benzothiadiazole (TBT) and the photocatalytic activity was systematically investigated by introducing and varying the position of methyl side chains on the two peripheral thiophene units. Experimental and theoretical results indicated that the introduction of -CH3 group at the 3-position of TBT resulted in the smallest size and best crystallinity of aggregates compared to that of TBT, 4- and 5-positions. As a result, TBT-3 exhibited an excellent photocatalytic activity towards H2 evolution, ascribed to the shorten charge carrier transport distance and solid long-range order.  These results suggest the important role of aggregation behavior of OCSs for efficient photocatalysis.}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Yuan, Xiaojiao and Yang, Kunran and Grazon, Chloe and Wang, Cong and Vallan, Lorenzo and Isasa, Jean-David and Resende, Pedro M. and Li, Fanxing and Brochon, Cyril and Remita, Hynd and et al.}, year={2023}, month={Dec} }
 @article{rahmanian_ebrahim_razavi_abdelmigeed_barbieri_menegatti_parsons_li_pirzada_khan_2023, title={Vapor phase synthesis of metal-organic frameworks on a nanofibrous aerogel creates enhanced functionality}, volume={11}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/D3TA05299K}, DOI={10.1039/D3TA05299K}, abstractNote={Vapor-phase synthesis of metal–organic frameworks (MOFs) on nanofibrous aerogels provides a hierarchically porous and mechanically robust material platform for use in a multitude of applications, from carbon dioxide capture to heavy metal removal.}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Rahmanian, Vahid and Ebrahim, Muhammed Ziauddin Ahmad and Razavi, Seyedamin and Abdelmigeed, Mai and Barbieri, Eduardo and Menegatti, Stefano and Parsons, Gregory N. and Li, Fanxing and Pirzada, Tahira and Khan, Saad A.}, year={2023}, month={Nov} }
 @article{gu_song_niu_zhao_gao_li_2022, title={<p>Sr2CeO4 as a robust high temperature sorbent for CO2 capture with near 100% sorbent conversion efficiency</p>}, volume={441}, ISSN={["1873-3212"]}, url={https://doi.org/10.1016/j.cej.2022.135942}, DOI={10.1016/j.cej.2022.135942}, abstractNote={As a typical CO2 capture and storage (CCS) technology, sorbent looping CO2 capture (SLCC) can be incorporated into CO2-related processes to enable potential revenue. The main challenge of the SLCC is the poor reactivity stability and limited operation temperature of sorbent. High temperature sorbent of SrO was prepared with sol–gel method and the carbonation/calcination performance was evaluated in thermogravimetry. The effect of different support materials (Al2O3, Y2O3, MgO, CeO2 and ZrO2) on the reactivity stability was initially evaluated during 25 carbonation/calcination cycles. The CeO2 supported sorbent exhibited super stable CO2 capture performance, whereas other materials could not stabilize the sorbent reactivity over multiple cycles. Afterwards, the effect of CeO2 loading on the sorbent reactivity, microstructure and phase transition was further identified. The results indicate that the Ce-Sr interaction induced new decarbonation path of SrCO3 + CeO2 = Sr2CeO4 + CO2 instead of conventional thermal sorbent decomposition of SrCO3 = SrO + CO2. It promoted the reaction kinetic and enabled the carbonation/calcination at a lower temperature. Also, it improved the microstructure and the sintering resistance, promoting sorbent reactivity stability. The ratio of Ce/Sr higher than 0.5 was necessary to obtain a stable CO2 capture performance with almost 100% sorbent efficiency over multiple cycles.}, journal={CHEMICAL ENGINEERING JOURNAL}, publisher={Elsevier BV}, author={Gu, Haiming and Song, Guohui and Niu, Miaomiao and Zhao, Shanhui and Gao, Yunfei and Li, Fanxing}, year={2022}, month={Aug} }
 @article{gao_wang_corolla_eldred_bose_gao_li_2022, title={Alkali metal halide-coated perovskite redox catalysts for anaerobic oxidative dehydrogenation of n-butane}, volume={8}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.abo7343}, DOI={10.1126/sciadv.abo7343}, abstractNote={Oxidative dehydrogenation (ODH) of n-butane has the potential to efficiently produce butadiene without equilibrium limitation or coke formation. Despite extensive research efforts, single-pass butadiene yields are limited to <23% in conventional catalytic ODH with gaseous O2. This article reports molten LiBr as an effective promoter to modify a redox-active perovskite oxide, i.e., La0.8Sr0.2FeO3 (LSF), for chemical looping–oxidative dehydrogenation of n-butane (CL-ODHB). Under the working state, the redox catalyst is composed of a molten LiBr layer covering the solid LSF substrate. Characterizations and ab initio molecular dynamics (AIMD) simulations indicate that peroxide species formed on LSF react with molten LiBr to form active atomic Br, which act as reaction intermediates for C─H bond activation. Meanwhile, molten LiBr layer inhibits unselective CO2 formation, leading to 42.5% butadiene yield. The redox catalyst design strategy can be extended to CL-ODH of other light alkanes such as iso-butane conversion to iso-butylene, providing a generalized approach for olefin production.}, number={30}, journal={SCIENCE ADVANCES}, author={Gao, Yunfei and Wang, Xijun and Corolla, Noel and Eldred, Tim and Bose, Arnab and Gao, Wenpei and Li, Fanxing}, year={2022}, month={Jul} }
 @article{brody_neal_liu_li_2022, title={Autothermal Chemical Looping Oxidative Dehydrogenation of Ethane: Redox Catalyst Performance, Longevity, and Process Analysis}, volume={7}, ISSN={["1520-5029"]}, DOI={10.1021/acs.energyfuels.2c01293}, abstractNote={Energy-efficient upgrading of stranded ethane from shale gas to olefins holds the promise of increasing the supply of useful chemical feedstocks while reducing flaring-based CO2 emissions. Previously, we reported a modular ethane-to-liquids (M-ETL) system based on a chemical looping oxidative dehydrogenation (CL-ODH) scheme. In this article, we present long-term (>1200 h) results of Li2CO3-promoted La0.8Sr0.2FeO3 corresponding to ∼4125 CL-ODH cycles in a large laboratory-scale packed bed reactor. Temperature monitoring along the bed length confirmed the exothermicity of both the oxidative dehydrogenation and regeneration steps, enabling an autothermal operation. Product gas analysis indicated that the redox catalyst maintains a high C2+ selectivity (∼90%) and ethane conversion (∼67%) at 735 °C after continuous cycling of >1000 h. Product distributions and heats of reactions were used to update our M-ETL process model for revised techno-economic analysis, demonstrating that the current system is economically viable with relatively low required selling prices across a wide range of operating scenarios.}, journal={ENERGY & FUELS}, author={Brody, Leo and Neal, Luke and Liu, Junchen and Li, Fanxing}, year={2022}, month={Jul} }
 @article{tian_westmoreland_li_2022, title={CaMn0.9Ti0.1O3 based redox catalysts for chemical looping – Oxidative dehydrogenation of ethane: Effects of Na2MoO4 promoter and degree of reduction on the reaction kinetics}, volume={417}, ISSN={0920-5861}, url={http://dx.doi.org/10.1016/j.cattod.2022.04.026}, DOI={10.1016/j.cattod.2022.04.026}, abstractNote={Reduction kinetics and stability of 20 wt% Na2MoO4-promoted CaMn0.9Ti0.1O3 were investigated for its applications in Chemical Looping – Oxidative Dehydrogenation (CL-ODH) of ethane, a potential alternative for ethylene production with higher efficiency and lower emissions. The present work reports a kinetics model and parameters for a Na2MoO4-promoted, Ti-doped CaMnO3 (CaMn0.9Ti0.1O3) redox catalyst under H2 and C2H4. A first-order reaction model provides the best fit for the reduction of Na2MoO4/CaMn0.9Ti0.1O3 under H2, while the C2H4 reduction is well described by an Avrami–Erofe’ev model. The activation energy for C2H4 oxidation is approximately three times higher than that for H2 conversion, showing that the activation of C2H4 is significantly more difficult on the surface of the redox catalyst. The reduction rate of Na2MoO4/CaMn0.9Ti0.1O3 under H2 at 750 °C is more than two orders of magnitude greater than that under C2H4, while the reduction rate of unpromoted CaMn0.9Ti0.1O3 is comparable under H2 and C2H4, showing that the addition of Na2MoO4 effectively suppresses C2H4 combustion relative to H2 oxidation. The kinetics results for Na2MoO4/CaMn0.9Ti0.1O3 confirm its excellent selectivity towards hydrogen combustion, making it a promising candidate under CL-ODH. Additionally, the stability of the CaMn0.9Ti0.1O3@ Na2MoO4 core-shell structure, which was the underlying reason for the excellent selectivity, was examined under both shallow and deep reductions. It was determined that deep reduction of the redox catalyst, e.g. higher than 80% solid conversion, would lead to loss of sodium and hence to decreased selectivity for hydrogen combustion. In contrast, the core-shell structure was well-maintained, exhibiting excellent performance after 50 redox cycles when deep reduction of the redox catalyst was avoided. This study offers a basis for both the CL-ODH reactor design and redox catalyst optimizations.}, journal={Catalysis Today}, publisher={Elsevier BV}, author={Tian, Yuan and Westmoreland, Phillip R. and Li, Fanxing}, year={2022}, month={Apr} }
 @article{jasper_rafati_schimmel_shahbazi_li_mba-wright_wang_2022, title={Carbon negative transportation fuels - A techno-economic-environmental analysis of biomass pathways for transportation}, volume={14}, ISSN={["2590-1745"]}, DOI={10.1016/j.ecmx.2022.100208}, abstractNote={Global warming and fossil fuel depletion have necessitated alternative sources of energy. Biomass is a promising fuel source because it is renewable and can be carbon negative, even without carbon capture and storage. This study considers biomass as a clean, renewable source for transportation fuels. An Aspen Plus process simulation model was built of a biomass gasification biorefinery with Fischer-Tropsch (FT) synthesis of liquid fuels. A GaBi life cycle assessment model was also built to determine the environmental impacts using a cradle-to-grave approach. Three different product pathways were considered: Fischer-Tropsch synthetic diesel, hydrogen, and electricity. An offgas autothermal reformer with a recycle loop was used to increase FT product yield. Different configurations and combinations of biorefinery products are considered. The thermal efficiency and cost of production of the FT liquid fuels are analyzed using the Aspen Plus process model. The greenhouse gas emissions, profitability, and mileage per kg biomass were compared. The mileage traveled per kilogram biomass was calculated using modern (2019–2021) diesel, electric, and hydrogen fuel cell vehicles. The overall thermal efficiency was found to be between 20 and 41% for FT fuels production, between 58 and 61% for hydrogen production, and around 25–26% for electricity production for this biorefinery. The lowest production costs were found to be $3.171/gal of FT diesel ($24.304/GJ), $1.860/kg of H2 ($15.779/GJ), and 13.332¢/kWh for electricity ($37.034/GJ). All configurations except one had net negative carbon emissions over the life cycle of the biomass. This is because carbon is absorbed in the trees initially, and some of the carbon is sequestered in ash and unconverted char from the gasification process, furthermore co-producing electricity while making transportation fuel offsets even more carbon emissions. Compared to current market rates for diesel, hydrogen, and electricity, the most profitable biorefinery product is shown to be hydrogen while also having net negative carbon emissions. FT diesel can also be profitable, but with a slimmer profit margin (not considering government credits) and still having net negative carbon emissions. However, our biorefinery could not compete with current commercial electricity prices in the US. As oil, hydrogen, and electricity prices continue to change, the economics of the biorefinery and the choice product will change as well. For our current biorefinery model, hydrogen seems to be the most promising product choice for profit while staying carbon negative, while FT diesel is the best choice for sequestering the most carbon and still being profitable.}, journal={ENERGY CONVERSION AND MANAGEMENT-X}, author={Jasper, Micah and Rafati, Navid and Schimmel, Keith and Shahbazi, Abolghasem and Li, Fanxing and Mba-Wright, Mark and Wang, Lijun}, year={2022}, month={May} }
 @article{dou_funderburg_yang_liu_chacko_zhang_harvey_haribal_zhou_li_2022, title={CexZr1-xO(2)-Supported CrOx Catalysts for CO2-Assisted Oxidative Dehydrogenation of Propane -Probing the Active Sites and Strategies for Enhanced Stability}, volume={12}, ISSN={["2155-5435"]}, url={https://doi.org/10.1021/acscatal.2c05286}, DOI={10.1021/acscatal.2c05286}, abstractNote={CO2-assisted oxidative dehydrogenation of propane (CO2-ODH) represents an attractive approach for propylene production and CO2 utilization. As a soft oxidant, CO2 can minimize overoxidation of the hydrocarbons to enhance the propylene selectivity while increasing the equilibrium yield. However, a major challenge of CO2-ODH is the rapid deactivation of the catalysts. The current study focuses on designing CexZr1–xO2-mixed oxide-supported CrOx catalysts for CO2-ODH with enhanced product selectivity and catalyst stability. By doping 0–30% Ce in the CexZr1–xO2 mixed oxide support, propane conversion of 53–79% was achieved at 600 °C, with propylene selectivity up to 82%. Compared to the pure ZrO2-supported catalyst (i.e., 5 wt %Cr/ZrO2), 20–30 %Ce doped catalysts (i.e., 5 wt %Cr/Ce0.2Zr0.8O2 and 5 wt %Cr/Ce0.3Zr0.7O2) inhibited the formation of CH4 and ethylene and improved propylene selectivity from 57 to 77–82%. Detailed characterizations of the 5%Cr/Ce0.2Zr0.8O2 catalyst and density functional theory (DFT) calculations indicated that Cr3+ is the active species during the CO2-ODH reaction, and the reaction follows a non-redox dehydrogenation pathway. Coke formation was determined to be the primary reason for catalyst deactivation, and the addition of Ce to the ZrO2 support greatly enhanced the coke resistance, leading to superior stability. Coke removal by oxidizing the catalyst in air is effective in restoring its activity.}, journal={ACS CATALYSIS}, author={Dou, Jian and Funderburg, Joey and Yang, Kunran and Liu, Junchen and Chacko, Dennis and Zhang, Kui and Harvey, Adam P. and Haribal, Vasudev P. and Zhou, S. James. and Li, Fanxing}, year={2022}, month={Dec} }
 @article{cai_dou_krzystowczyk_richard_li_2022, title={Chemical looping air separation with Sr0.8Ca0.2Fe0.9Co0.1O3-delta perovskite sorbent: Packed bed modeling, verification, and optimization}, volume={429}, ISSN={["1873-3212"]}, DOI={10.1016/j.cej.2021.132370}, abstractNote={Chemical looping air separation (CLAS) represents a promising approach for efficient O2 production from the air. The present study aims at optimizing the absorber/desorber operations and the separation process with extensive experimental validation. Specifically, a one-dimensional packed bed model was developed to investigate the CLAS operation with a Sr0.8Ca0.2Fe0.9Co0.1O3-δ perovskite sorbent. The redox thermodynamics of perovskite sorbent was measured by TGA and then incorporated into a linear driving force model to describe the O2 absorption and desorption rates. Both 4-step and 5-step air separation cycle configurations, with various cyclic structures, were performed in a subpilot-scale packed bed. The model predicted O2 purity and productivity were consistent with experimental results, supporting its accuracy and applicability. Parametric analysis and multi-objective optimization were further carried out to assess the performance of CLAS. Both O2 purity and recovery increased monotonically with the cycle time, airflow rate, steam flow rate, and absorption pressure. Meanwhile, optimal O2 productivity and power consumption can only be achieved by specific combinations of these parameters. The optimized results showed that CLAS can be highly competitive when compared to conventional pressure swing adsorption (PSA) or cryogenic distillation. The 5-step cycle configuration achieved a minimum power consumption of 118 kW·h for producing 1 ton O2 with ≥ 95% purity. The maximum O2 productivity reached 0.0932 gO2/(gsorbent·h) with 390 kW·h/ton O2 of energy consumption (95% pure). The optimization results also indicate that CLAS can potentially be more efficient than cryogenic distillation even when the required O2 purity is above 99%.}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Cai, Runxia and Dou, Jian and Krzystowczyk, Emily and Richard, Anthony and Li, Fanxing}, year={2022}, month={Feb} }
 @article{campbell_baro_gao_li_abolhasani_2022, title={Cover Picture: Flow Synthesis of Single and Mixed Metal Oxides (Chem. Methods 8/2022)}, volume={2}, url={https://doi.org/10.1002/cmtd.202200048}, DOI={10.1002/cmtd.202200048}, abstractNote={The Front Cover shows a versatile flow synthesis strategy for continuous manufacturing of single- and mixed-metal oxide particles with a high degree of size monodispersity. The flow-focusing microreactor equipped with an online photo-crosslinking module enables facile production of a broad range of monodispersed metal oxide particles (ZnO, SnO2, CeO2, LaPrO3) using metal organic precursors beyond metal alkoxides. More information can be found in the Research Article by Zachary S. Campbell et al..}, number={8}, journal={Chemistry–Methods}, publisher={Wiley}, author={Campbell, Zachary S. and Baro, Steven and Gao, Yunfei and Li, Fanxing and Abolhasani, Milad}, year={2022}, month={Aug} }
 @article{campbell_baro_gao_li_abolhasani_2022, title={Flow Synthesis of Single and Mixed Metal Oxides}, volume={2}, url={https://doi.org/10.1002/cmtd.202200007}, DOI={10.1002/cmtd.202200007}, abstractNote={Abstract A generalizable and versatile microfluidic approach for facile synthesis of a wide range of metal oxide microparticles using atypical metal‐organic precursors is reported. Microparticles of three single oxide materials, zinc(II) oxide, tin(IV) oxide, and cerium(IV) oxide, as well as a binary rare earth mixed oxide, lanthanum(III) praseodymium(III) oxide, are synthesized in flow. The tin(IV) oxide is shown to vary in composition from 14.2 % to 0 % orthorhombic phase at annealing temperatures ranging from 500 °C to 900 °C, while the lanthanum(III) praseodymium(III) oxide forms at a relatively low temperature of ∼700 °C.}, number={8}, journal={Chemistry–Methods}, publisher={Wiley}, author={Campbell, Zachary S. and Baro, Steven and Gao, Yunfei and Li, Fanxing and Abolhasani, Milad}, year={2022}, month={Aug} }
 @article{wang_gao_krzystowczyk_iftikhar_dou_cai_wang_ruan_ye_li_2022, title={High-throughput oxygen chemical potential engineering of perovskite oxides for chemical looping applications}, volume={15}, ISSN={["1754-5706"]}, url={https://doi.org/10.1039/D1EE02889H}, DOI={10.1039/d1ee02889h}, abstractNote={Chemical looping (CL) represents a versatile, emerging strategy for sustainable chemical and energy conversion. Designing metal oxide oxygen carriers with suitable redox properties remains one of the most critical challenges...}, number={4}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, publisher={Royal Society of Chemistry (RSC)}, author={Wang, Xijun and Gao, Yunfei and Krzystowczyk, Emily and Iftikhar, Sherafghan and Dou, Jian and Cai, Runxia and Wang, Haiying and Ruan, Chongyan and Ye, Sheng and Li, Fanxing}, year={2022}, month={Feb} }
 @article{iftikhar_martin_gao_yu_wang_wu_li_2022, title={LaNixFe1−xO3 as flexible oxygen or carbon carriers for tunable syngas production and CO2 utilization}, volume={416}, ISSN={0920-5861}, url={http://dx.doi.org/10.1016/j.cattod.2022.07.022}, DOI={10.1016/j.cattod.2022.07.022}, abstractNote={The current study reports LaFe1−xNixO3−δ redox catalysts as flexible oxygen or carbon carriers for CO2 utilization and tunable production of syngas at relatively low temperatures (∼700 °C), in the context of a hybrid redox process. Specifically, perovskite-structured LaFe1−xNixO3−δ with seven different compositions (x = 0.4–1) were prepared and investigated. Cyclic experiments under alternating methane and CO2 flows indicated that all the samples exhibited favorable reactive performance: CH4 and CO2 conversions varied between 85% and 98% and 70–88%, respectively. While H2/CO ratio from Fe-rich redox catalysts was ~2.3:1 in the methane conversion step, Ni-rich catalysts produced a concentrated (~ 93.7 vol%) hydrogen stream via methane cracking. The flexibility of LaFe1−xNixO3−δ to produce syngas (or hydrogen) with tunable compositions was found to be governed by the iron/nickel (Fe/Ni) ratio. Redox catalysts with higher Fe contents act as a lattice oxygen carrier via chemical looping partial oxidation (CLPOx) of methane whereas those with higher Ni contents function as a carbon carrier via chemical looping methane cracking (CLMC) scheme. XRD analysis and temperature-programmed reactions revealed that both types of catalysts involve the formation of La2O3 and Ni0 /Ni-Fe phases under the methane environment. The ability to re-incorporate La2O3 and Ni/Fe into a perovskite structure gives rise to oxygen-carrying capacity whereas stable Ni0 or Ni/Fe phases would catalyze methane cracking without lattice oxygen exchange in the reaction cycles. Temperature programmed oxidation and Raman spectroscopy indicated the presence of graphitic and amorphous carbon species, which were effectively gasified by CO2 to produce concentrated CO. Stability tests over LaFe0.5Ni0.5O3 and LaNiO3 revealed that the redox performance was stable over a span of 50 cycles.}, journal={Catalysis Today}, publisher={Elsevier BV}, author={Iftikhar, Sherafghan and Martin, William and Gao, Yunfei and Yu, Xinbin and Wang, Iwei and Wu, Zili and Li, Fanxing}, year={2022}, month={Jul} }
 @article{jiang_wang_bai_balyan_robinson_hu_li_deibel_liu_li_et al._2022, title={Methane Catalytic Pyrolysis by Microwave and Thermal Heatingover Carbon Nanotube-Supported Catalysts: Productivity, Kinetics,and Energy Efficiency br}, volume={61}, ISSN={["0888-5885"]}, DOI={10.1021/acs.iecr.1c05082}, abstractNote={Methane catalytic pyrolysis, which is the reaction to produce hydrogen and carbon without emitting CO2, represents an approach for decarbonization using natural gas as an energy resource. The endothermic pyrolysis reaction was carried out under two heating scenarios: convective thermal heating and microwave-driven irradiative heating. The pyrolysis reaction was conducted at 550–600 °C over carbon nanotube (CNT)-supported Ni–Pd and Ni–Cu catalysts. On both catalysts, an enhanced methane conversion rate was observed under microwave irradiation. The enhanced catalytic activity was hypothetically caused by the presence of free electrons in the carbon atoms within the CNT that enabled the CNT support to absorb microwave energy effectively and to be heated efficiently by microwave. The microwave catalytic pyrolysis has shown improvement in kinetics, where the apparent activation energy dropped from 45.5 kJ/mol under conventional convective heating to 24.8 kJ/mol under microwave irradiation. When the methane conversion rate is increased by 37%, the microwave power consumption only changed by 10.8%. The research demonstrated the potential of transforming natural gas into clean hydrogen and value-added carbon in a more energy-efficient way. Process simulation and techno-economic analysis showed that potentially hydrogen minimum selling price of about $1/kg H2 could be achieved.}, number={15}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Jiang, Changle and Wang, I-Wen and Bai, Xinwei and Balyan, Sonit and Robinson, Brandon and Hu, Jianli and Li, Wenyuan and Deibel, Angela and Liu, Xingbo and Li, Fanxing and et al.}, year={2022}, month={Apr}, pages={5080–5092} }
 @article{liu_li_2022, title={Mixed oxides as multi-functional reaction media for chemical looping catalysis}, volume={12}, ISSN={["1364-548X"]}, url={https://doi.org/10.1039/D2CC05502C}, DOI={10.1039/D2CC05502C}, abstractNote={Over the past two decades, chemical looping combustion (CLC) has been extensively investigated as a promising means to produce electric power while generating a concentrated carbon dioxide stream for sequestration. We note that the chemical looping strategy can be extended well outside of combustion-based carbon capture. In fact, application of the chemical looping strategy in areas beyond combustion can result in somewhat unexpected energy and carbon dioxide savings without producing a concentrated CO2 stream at all. Furthermore, it allows the looping-based technologies to tap into applications such as chemical production - a $4 trillion per year industrial sector with high energy and carbon intensities. The key resides in the design of effective oxygen carriers, also known as redox catalysts in the context of selective chemical conversion through chemical looping catalysis (CLCa). This contribution focuses on the design and applications of mixed oxides as multi-function reaction media in CLCa. Since typical mixed oxide oxygen carriers tend to be nonselective for hydrocarbon conversion, the first part of this article presents generalized design principles for surface modification of mixed oxides to improve their selectivity and catalytic activity. Applications of these redox catalysts in chemical looping - oxidative dehydrogenation (CL-ODH) of a variety of light alkanes and alkyl-benzenes are presented. This is followed with a discussion of computation assisted mixed oxide design based upon thermodynamic criteria. Finally, a few new directions for the chemical looping technologies are introduced.}, journal={CHEMICAL COMMUNICATIONS}, author={Liu, Junchen and Li, Fanxing}, year={2022}, month={Dec} }
 @article{tian_luongo_donat_müller_larring_westmoreland_li_2022, title={Oxygen Nonstoichiometry and Defect Models of Brownmillerite-Structured Ca<sub>2</sub>MnAlO<sub>5+δ</sub> for Chemical Looping Air Separation}, volume={10}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/acssuschemeng.2c03485}, DOI={10.1021/acssuschemeng.2c03485}, abstractNote={Brownmillerite-structured Ca2MnAlO5+δ has demonstrated excellent oxygen storage capacity that can be used for chemical looping air separation (CLAS), a potentially efficient approach to produce high-purity oxygen from air. To effectively utilize this material as an oxygen sorbent in CLAS, it is necessary to comprehensively understand its thermodynamic properties and the structure–performance relationships in the operating range of interest. In this work, the oxygen nonstoichiometry (δ) of Ca2MnAlO5+δ was systematically measured by thermogravimetric analysis (TGA) in the temperature ranging from 440 to 660 °C and under an oxygen partial pressure ranging from 0.01 to 0.8 atm. The partial molar enthalpy and entropy for the oxygen-releasing reaction were calculated using the van’t Hoff equation with an average value of 146.5 ± 4.7 kJ/mol O2 and 162.7 ± 5.1 J/K mol O2, respectively. The experimentally measured nonstoichiometry (δ) was well fitted by a point defect model applied in two regions divided by the predicted equilibrium P–T curve. The equilibrium constants for appropriate defect reactions were also determined. The thermochemical parameters, molar enthalpy and entropy for the main reaction, obtained from the defect model were 136.9 kJ/mol O2 and 225.3 J/K mol O2, respectively, showing reasonable agreement with the aforementioned values. The applicability of the defect model was also verified at a higher oxygen partial-pressure environment of up to 4 atm and exhibited reasonable prediction of the trend. The experimental studies on oxygen nonstoichiometry combined with the defect modeling provide useful insights into oxygen sorbents’ redox performances and helpful information for the design and optimization of oxygen sorbents in CLAS.}, number={31}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Tian, Yuan and Luongo, Giancarlo and Donat, Felix and Müller, Christoph R. and Larring, Yngve and Westmoreland, Phillip R. and Li, Fanxing}, year={2022}, month={Jul}, pages={10393–10402} }
 @article{brody_cai_thornton_liu_yu_li_2022, title={Perovskite-Based Phase Transition Sorbents for Sorption-Enhanced Oxidative Steam Reforming of Glycerol}, volume={10}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.2c01323}, abstractNote={Sorption-enhanced steam reforming represents an efficient strategy to produce concentrated hydrogen from superfluous carbonaceous feedstocks. However, commonly used CaO-based sorbents are prone to sintering, leading to a rapid loss in CO2 sorption capacity and activity under repeated reaction cycles. Herein, we report perovskite-based phase transition sorbents (PTSs) capable of avoiding sintering and retaining both catalytic activity and sorption capacity. Specifically, A- and B-site doped SrFeO3−δ, that is, Sr1–xCaxFe1–yNiyO3−δ (SCFN), were evaluated as PTSs for the sorption-enhanced steam reforming of glycerol. Packed bed reactor experiments were performed in conjunction with redox, bulk, surface, and morphology characterizations to evaluate SCFN’s performance and the underlying phase transition scheme. These characterizations revealed that reduced oxides from the A-site of the PTS (SrO, CaO) are carbonated during the reforming step before reversibly undergoing decarbonation at a higher temperature under an oxidizing environment. This study demonstrates that SCFN is a trifunctional material capable of (i) catalyzing the reforming of glycerol, (ii) absorbing CO2 in situ, and (iii) reversibly releasing oxygen from lattice sites to enhance glycerol conversion. While all of the screened compositions achieved >87 vol % pre-breakthrough H2 purities, SCFN-4691 (Sr0.4Ca0.6Fe0.9Ni0.1O3−δ) and SCFN-5591 (Sr0.5Ca0.5Fe0.9Ni0.1O3−δ) showed particularly high (95.6–97.3%) H2 purities with stable CO2 sorption capacities.}, number={19}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Brody, Leo and Cai, Runxia and Thornton, Alajia and Liu, Junchen and Yu, Hao and Li, Fanxing}, year={2022}, month={May}, pages={6434–6445} }
 @book{krzystowczyk_dou_li_2022, title={Radically Engineered Modular Air Separation System with Tailored Oxygen Sorbents}, url={https://doi.org/10.2172/1862110}, DOI={10.2172/1862110}, abstractNote={The commercial energy sector relies heavily on fossil fuel conversion, and in the process releases a significant amount of CO2. A promising technology to utilize fossil fuels with relatively affordable CO2 capture is gasification. However, it requires a pure oxygen stream. The current state of the art method to produce oxygen is cryogenic air separation, which supercools air to a liquid, and then using distillation columns to separate the components. While this method has been thoroughly studied, it only has a 25% efficiency from a second law standpoint and therefore requires a significant amount of energy (and associated emissions) for oxygen production. This, then, lowers the incentive for carbon capture within a plant, so alternative methods need to be investigated. One potential method, chemical looping air separation (CLAS), is a promising method to replace state of the art oxygen generation technologies. CLAS utilizes a cyclic redox scheme with an oxygen sorbent to create pure oxygen streams. This approach typically utilizes a dual reactor scheme where the oxygen deficient sorbent enters the first reactor and is subjected to high oxygen partial pressures to re-oxidize the sorbent. Then the sorbent is sent to the reducing reactor, where it is subjected to low oxygen partial pressure (steam or vacuum) to releases oxygen. The overarching objective of this project was to discover the principles for rational design and optimization of oxygen sorbents and process design to ensure the process is a viable replacement for cryogenic air separation, especially in the context of modular gasification systems. This was done through development, characterization, testing, and analyses of (a) high temperature mixed composite oxides; (b) low temperature doped perovskite oxides (A1xA21-xB1yB21-yO3); (c) scale up synthesis and testing of the optimized sorbent particles; (d) process design and analyses of the CLAS system in the context of modular gasification applications.}, institution={Office of Scientific and Technical Information (OSTI)}, author={Krzystowczyk, Emily and Dou, Jian and Li, Fanxing}, year={2022}, month={Apr} }
 @article{liu_yusuf_jackson_martin_chacko_vogt-lowell_neal_li_2022, title={Redox oxide@molten salt as a generalized catalyst design strategy for oxidative dehydrogenation of ethane via selective hydrogen combustion}, volume={646}, ISSN={["1873-3875"]}, DOI={10.1016/j.apcata.2022.118869}, abstractNote={The current study demonstrates a redox oxide @ molten salt core-shell architecture as a generalized redox catalyst design strategy for chemical looping – oxidative dehydrogenation of ethane. 17 combinations of redox active oxides and molten salts were prepared, evaluated, and characterized. X-ray diffraction indicates that the redox oxides and molten salts are fully compatible, forming separate and stable phases. X-ray photoelectron spectroscopy demonstrates that the molten salts aggregate at the redox oxide surface, forming a core-shell structure to block the non-selective sites responsible for COx formation. Up to ∼74 % single-pass olefin yields were achieved using the proposed redox catalyst design strategy. Statistical analyses of the performance data indicate the potential to achieve up to 86.7 % single-pass yield by simply optimizing the operating conditions using the redox catalysts reported in this study. Meanwhile, the generalizability of the catalyst design strategy offers exciting opportunities to further optimize the composition and performance of the redox catalysts for ethane ODH under a chemical looping scheme with significantly reduced energy consumption and CO2 emissions.}, journal={APPLIED CATALYSIS A-GENERAL}, author={Liu, Junchen and Yusuf, Seif and Jackson, Daniel and Martin, William and Chacko, Dennis and Vogt-Lowell, Kyle and Neal, Luke and Li, Fanxing}, year={2022}, month={Sep} }
 @article{wang_yang_ji_gao_li_zhang_wei_2022, title={Reduction kinetics of SrFeO3-delta/CaO center dot MnO nanocomposite as effective oxygen carrier for chemical looping partial oxidation of methane}, volume={11}, ISSN={["2095-0187"]}, DOI={10.1007/s11705-022-2188-5}, journal={FRONTIERS OF CHEMICAL SCIENCE AND ENGINEERING}, author={Wang, Xinhe and Yang, Liuqing and Ji, Xiaolin and Gao, Yunfei and Li, Fanxing and Zhang, Junshe and Wei, Jinjia}, year={2022}, month={Nov} }
 @article{iftikhar_martin_wang_liu_gao_li_2022, title={Ru-promoted perovskites as effective redox catalysts for CO2 splitting and methane partial oxidation in a cyclic redox scheme}, volume={11}, ISSN={["2040-3372"]}, url={https://doi.org/10.1039/D2NR04437D}, DOI={10.1039/D2NR04437D}, abstractNote={The current study reports AxA'1-xByB'1-yO3-δ perovskite redox catalysts (RCs) for CO2-splitting and methane partial oxidation (POx) in a cyclic redox scheme. Strontium (Sr) and iron (Fe) were chosen as A and B site elements with A' being lanthanum (La), samarium (Sm) or yttrium (Y), and B' being manganese (Mn) or titanium (Ti) to tailor their equilibrium oxygen partial pressures (PO2s) for CO2-splitting and methane partial oxidation. DFT calculations were performed for predictive optimization of the oxide materials whereas experimental investigation confirmed the DFT-predicted redox performance. The redox kinetics of the RCs improved significantly by 1 wt% ruthenium (Ru) impregnation without affecting their redox thermodynamics. Ru-impregnated LaFe0.375Mn0.625O3 (A = 0, A' = La, B = Fe, and B' = Mn) was the most promising RC in terms of its superior redox performance (CH4/CO2 conversion >90% and CO selectivity ∼95%) at 800 °C. Long-term redox testing over Ru-impregnated LaFe0.375Mn0.625O3 indicated a stable performance during the first 30 cycles followed by an ∼25% decrease in the activity during the last 70 cycles. Air treatment was effective to reactivate the redox catalyst. Detailed characterizations revealed the underlying mechanism of the redox catalyst deactivation and reactivation. This study not only validated a DFT-guided mixed oxide design strategy for CO2 utilization but also provides potentially effective approaches to enhance redox kinetics and long-term redox catalyst performance.}, journal={NANOSCALE}, author={Iftikhar, Sherafghan and Martin, William and Wang, Xijun and Liu, Junchen and Gao, Yunfei and Li, Fanxing}, year={2022}, month={Nov} }
 @article{ruan_wang_wang_zheng_li_lin_liu_li_wang_2022, title={Selective catalytic oxidation of ammonia to nitric oxide via chemical looping}, volume={13}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-022-28370-0}, DOI={10.1038/s41467-022-28370-0}, abstractNote={Selective oxidation of ammonia to nitric oxide over platinum-group metal alloy gauzes is the crucial step for nitric acid production, a century-old yet greenhouse gas and capital intensive process. Therefore, developing alternative ammonia oxidation technologies with low environmental impacts and reduced catalyst cost are of significant importance. Herein, we propose and demonstrate a chemical looping ammonia oxidation catalyst and process to replace the costly noble metal catalysts and to reduce greenhouse gas emission. The proposed process exhibit near complete NH3 conversion and exceptional NO selectivity with negligible N2O production, using nonprecious V2O5 redox catalyst at 650 oC. Operando spectroscopy techniques and density functional theory calculations point towards a modified, temporally separated Mars-van Krevelen mechanism featuring a reversible V5+/V4+ redox cycle. The V = O sites are suggested to be the catalytically active center leading to the formation of the oxidation products. Meanwhile, both V = O and doubly coordinated oxygen participate in the hydrogen transfer process. The outstanding performance originates from the low activation energies for the successive hydrogen abstraction, facile NO formation as well as the easy regeneration of V = O species. Our results highlight a transformational process in extending the chemical looping strategy to producing base chemicals in a sustainable and cost-effective manner.}, number={1}, journal={NATURE COMMUNICATIONS}, publisher={Springer Science and Business Media LLC}, author={Ruan, Chongyan and Wang, Xijun and Wang, Chaojie and Zheng, Lirong and Li, Lin and Lin, Jian and Liu, Xiaoyan and Li, Fanxing and Wang, Xiaodong}, year={2022}, month={Feb} }
 @book{li_iftikhar_neal_2022, title={Sustainable Conversion of Carbon Dioxide and Shale Gas to Green Acetic Acid via a Thermochemical Cyclic Redox Scheme (Final Report)}, url={https://doi.org/10.2172/1895614}, DOI={10.2172/1895614}, abstractNote={The large-scale production of commodity chemicals relies heavily on the combustion of fossil fuels. As a result, enormous amounts of carbon dioxide (CO2) are emitted which severely affects the global climate. The challenges for CO2 utilization reside in the high stability of CO2 molecules relative to the products, which requires the addition of significant external energy and overcoming slow and/or unfavorable reaction kinetics/thermodynamics. Chemical looping dry reforming of methane (CLDRM), also known as a hybrid redox process (HRP), is a promising alternative that allows the utilization of CO2 and domestic shale gas resources to produce commodity chemicals. HRP works in two steps: In the first step, a redox catalyst reacts with methane to yield synthesis gas (R1) with a H2/CO ratio near 2:1, which is suitable for methanol and Fischer–Tropsch synthesis. The reduced redox catalyst then reacts with an oxidizing agent, such as CO2, to yield CO (R2). In comparison to conventional thermochemical CO2 splitting approaches, the use of methane as the reducing agent in HRP can significantly lower the operating temperature for CO2 splitting. The advancement of the HRP technology for production of commodity chemicals relies heavily on the development of the redox catalysts (RCs). Therefore, the initial RC screening was done by synthesizing , characterizing , and selecting more than 6 redox materials with improved redox kinetics compared to the CaO-SrFeO3 reference material. The initial screening indicated that by doping the RCs with a platinum group metal (PGM) such as rhodium (Rh), the redox performance can be enhanced significantly. Further RC optimization was done to down select 4 PGM free redox catalysts which showed >20% CO2/POx kinetics improvements and/or >40% per cycle CO yield increase vs the CaO-SrFeO3 reference material. The improved redox performance was found to be due to the synergy between mixed composites of perovskite-type RC (LaNi0.35Fe0.65O3, LNF) and rocksalt-structured Ce0.85Gd0.1Cu0.05O2-δ(CGCO). Further optimization of the perovskite-type RC (LaNi1-xFexO3) revealed that the redox performance of composite CGCO/LNF was comparable to that of standalone LNF, signifying the potential of standalone LNF as a simple yet effective redox catalyst. In addition to the trial and error-based catalyst optimization, the DFT-guided mixed oxide design strategy was also considered which was experimentally validated and shown to be highly effective in further optimizing the redox catalysts for CO2 utilization. To find the initial kinetic parameters for the reactor design two RCs were chosen and their kinetic parameters were found. The results indicated that the rate of the reference SrFeO3 redox catalyst at 700°C is more than one order of magnitude smaller compared to the CGCO/LNF composites. These observations further confirmed the significance of the optimization we performed to find the RCs which are simple yet effective in terms of their redox kinetics. The kinetic parameters served as the basis for the reactor design which ultimately guided us to perform an initial techno-economic and life cycle analysis (TEA and LCA). The TEA and LCA indicated that HRP has an acetic acid production cost that is at least 34% lower than the baseline case of dry reforming of methane (DRM) without hydrogen product credit. Given the flexibility of an HRP process to produce tunable ratios of syngas, the product slate screening was also performed which indicated that along with the production of acetic acid, other reasonable products such as methanol, CO, and syngas can be produced. Our analysis also indicated that an HRP has the potential to produce 1,200 tonnes/day of acetic acid which equates to 2-3% of the current acetic acid market. Meanwhile, the CO2 footprint analysis indicated that the production of CO, syngas, methanol, and acetic acid via HRP was significantly less carbon intense than traditional processes. Based upon the lab-scale validated kinetics and extrapolated long-term activity, reactor size was estimated. The results indicated that for 1,200-tonnes/day acidic acid plant from a BSF of 600 lb/tonnes/day, near 100 tonnes of the RC is required. However, these findings needed further confirmation from long-term testing as it was assumed that the extrapolated kinetics would remain the same. To evaluate the long-term stability of the redox catalyst, a 0.75” I.D. packed bed reactor was used. The results indicated that the redox catalyst gradually loses its activity over repeated redox cycles, resulting in a 6% drop in methane conversion (from 86%) over 500 cycles. Periodic reactivation with air, e.g., every 40–50 redox cycles, was proposed as a strategy to maintain the long-term stability of the redox catalyst. Such a strategy was verified to be effective, as confirmed by operating the redox catalyst over 900 cumulative cycles while maintaining a satisfactory redox performance. Upon the confirmation of the stable long-term redox performance, preliminary reactor sizing/cost estimates and sensitivity analysis of HRP reactor price were performed to analyze and compare the overall plant economics of HRP with baseline cases such autothermal reforming (ATR) and steam methane reforming (SMR). The results indicated that, compared to the baseline case, an HRP can save up to 32% on capital/unit costs. In addition, it was also found that an HRP has the potential to reduce the overall energy requirement by 41% without considering waste heat sources. Meanwhile, the initial LCA demonstrated the potential of the HRP to operate close to net zero CO2 emissions. Based on this sensitivity analysis, the size of the reactor was optimized as well. A total bare erect cost (BEC) of $66.7M was estimated for the installation of 6 HRP fixed bed reactors for the continuous operation of producing 2,900 kmol/hr of syngas. At a catalyst charge of 65.52 tonnes per unit, this sizing gave a total catalyst charge of 393 tonnes. We also found that with a fixed bed reactor design described in this report, the estimated BEC (for the reactor) is $66.7MM, leading to an estimated breakeven acetic acid price of $375 per tonne or +46% potential gross margin. Finally, a commercialization roadmap was developed which indicated that the pilot plant testing should be demonstrated at a sufficiently large capacity to ensure the surface-to-volume ratio of the HRP reactor is small enough to all for autothermal operation, i.e., no external heat input required to compensate for heat loss from the reactor walls. In addition, representative shale gas and CO2 feed should be used to verify the sustained performance of the HRP catalyst and reactor design when subject to real operation conditions.}, author={Li, Fanxing and Iftikhar, Sherafghan and Neal, Luke}, year={2022}, month={Oct} }
 @article{zhu_gao_wang_haribal_liu_neal_bao_wu_wang_li_2021, title={A tailored multi-functional catalyst for ultra-efficient styrene production under a cyclic redox scheme}, volume={12}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-021-21374-2}, DOI={10.1038/s41467-021-21374-2}, abstractNote={Styrene is an important commodity chemical that is highly energy and CO2 intensive to produce. We report a redox oxidative dehydrogenation (redox-ODH) strategy to efficiently produce styrene. Facilitated by a multifunctional (Ca/Mn)1-xO@KFeO2 core-shell redox catalyst which acts as (i) a heterogeneous catalyst, (ii) an oxygen separation agent, and (iii) a selective hydrogen combustion material, redox-ODH auto-thermally converts ethylbenzene to styrene with up to 97% single-pass conversion and >94% selectivity. This represents a 72% yield increase compared to commercial dehydrogenation on a relative basis, leading to 82% energy savings and 79% CO2 emission reduction. The redox catalyst is composed of a catalytically active KFeO2 shell and a (Ca/Mn)1-xO core for reversible lattice oxygen storage and donation. The lattice oxygen donation from (Ca/Mn)1-xO sacrificially stabilizes Fe3+ in the shell to maintain high catalytic activity and coke resistance. From a practical standpoint, the redox catalyst exhibits excellent long-term performance under industrially compatible conditions.}, number={1}, journal={NATURE COMMUNICATIONS}, publisher={Springer Science and Business Media LLC}, author={Zhu, Xing and Gao, Yunfei and Wang, Xijun and Haribal, Vasudev and Liu, Junchen and Neal, Luke M. and Bao, Zhenghong and Wu, Zili and Wang, Hua and Li, Fanxing}, year={2021}, month={Feb} }
 @article{gu_gao_iftikhar_li_2021, title={Ce stabilized Ni-SrO as a catalytic phase transition sorbent for integrated CO2 capture and CH4 reforming}, volume={12}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/D1TA09967A}, DOI={10.1039/D1TA09967A}, abstractNote={Integration of carbon dioxide capture from flue gas with dry reforming of CH4 represents an attractive approach for CO2 utilization. The selection of a suitable bifunctional material serving as a...}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Gu, Haiming and Gao, Yunfei and Iftikhar, Sherafghan and Li, Fanxing}, year={2021}, month={Dec} }
 @article{krzystowczyk_haribal_dou_li_2021, title={Chemical Looping Air Separation Using a Perovskite-Based Oxygen Sorbent: System Design and Process Analysis}, volume={9}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.1c03612}, abstractNote={Oxygen is a critical industrial gas whose global market is projected to reach $48 billion/year within this decade. However, oxygen production is highly energy-intensive because of the limited efficiency of the commercial cryogenic air separation technology. The present study systematically investigated a chemical looping air separation (CLAS) approach as an alternative to cryogenic distillation. In particular, a Sr0.8Ca0.2Fe0.4Co0.6O3−δ (SCFC) oxygen sorbent was used as the basis for both experimental and simulation studies. To demonstrate the sorbent robustness, experimental studies were carried out over 10,000 redox cycles in a bench-scale testbed. Excellent sorbent stability and >90% oxygen purity were achieved using steam as the purge gas. Oxygen purity can be further increased to >95% by optimizing the operating conditions and pressure swing absorption cycle structure. Based on the experimental results, a CLAS system design and a process model were established. The process model estimates a base case CLAS energy consumption of 0.66 MJ/kg O2. This represents a 15% decrease compared to cryogenic air separation (0.78 MJ/kg O2). It is noted that most of the thermal energy consumed by CLAS is at relatively low temperatures (∼120 °C). When accounting for the quality of this low-grade heat, an energy consumption as low as 0.40 MJ/kg O2 can be anticipated for a practical system. Sensitivity analysis was also performed on the various CLAS operational and design parameters such as reactor sizes, pressure drop, thermodynamic driving forces, oxygen uptake and release rates, heat loss, and the energy consumption for steam generation. It was determined that CLAS has excellent potential to be an efficient oxygen production technology. This study also highlights the importance of developing advanced sorbents with suitable redox thermodynamics and fast redox kinetics for improved efficiency and smaller reactor sizes.}, number={36}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Krzystowczyk, Emily and Haribal, Vasudev and Dou, Jian and Li, Fanxing}, year={2021}, month={Sep}, pages={12185–12195} }
 @article{tian_zheng_li_zhao_2021, title={Co and Mo Co-doped Fe2O3 for Selective Ethylene Production via Chemical Looping Oxidative Dehydrogenation}, volume={9}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.1c02726}, abstractNote={In this study, we investigate Co and/or Mo doped Fe₂O₃ (CoₓMo₁–ₓ/Fe₂O₃, x = 0, 0.2, 0.3, 0.4, and 1) as redox catalysts for chemical looping oxidative dehydrogenation (CL-ODH) of ethane. Under the cyclic redox reaction mode, the five as-prepared samples behave differently toward ethane conversion. Among the five redox catalysts, CoFe₂O₄ (x = 1) is highly reactive and tends to overoxidize ethane into CO₂, while Mo/Fe₂O₃ (x = 0) exhibits promising ethylene selectivity but inferior H₂ removal capability. By tuning the molar ratio of Co/(Co + Mo), 87.4% ethylene selectivity at 56.2% ethane conversion can be achieved by the Co₀.₃Mo₀.₇/Fe₂O₃ (x = 0.3) redox catalyst at 825 °C and 6000 h–¹. C₂H₆-TPR results show that the selectivity of Co₀.₃Mo₀.₇/Fe₂O₃ alters as the ODH reaction proceeds due to the dynamic change of surface properties of the redox catalyst in the reaction. XPS results indicate that a relatively low Fe content as well as a high Mo content at the near-surface of the redox catalyst is beneficial for its ethylene selectivity in CL-ODH of ethane. DFT calculations reveal that Co cations in the Co₀.₃Mo₀.₇/Fe₂O₃ structure are responsible for the activity and H₂ combustion capability of the redox catalyst, while Mo plays a key role in tuning the ethylene selectivity.}, number={23}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Tian, Xin and Zheng, Chaohe and Li, Fanxing and Zhao, Haibo}, year={2021}, month={Jun}, pages={8002–8011} }
 @article{ohayon dahan_landau_vidruk nehemya_edri_herskowitz_ruan_li_2021, title={Core-Shell Fe2O3@La1-xSrxFeO3-delta Material for Catalytic Oxidations: Coverage of Iron Oxide Core, Oxygen Storage Capacity and Reactivity of Surface Oxygens}, volume={14}, ISSN={["1996-1944"]}, url={https://www.mdpi.com/1996-1944/14/23/7355}, DOI={10.3390/ma14237355}, abstractNote={A series of Fe2O3@LSF (La0.8Sr0.2FeO3−δ perovskite) core-shell materials (CSM) was prepared by infiltration of LSF precursors gel containing various complexants and their mixtures to nanocrystalline aggregates of hematite followed by thermal treatment. The content of LSF phase and amount of carboxyl groups in complexant determine the percent coverage of iron oxide core with the LSF shell. The most conformal coating core-shell material was prepared with citric acid as the complexant, contained 60 wt% LSF with 98% core coverage. The morphology of the CSM was studied by HRTEM-EELS combined with SEM-FIB for particles cross-sections. The reactivity of surface oxygen species and their amounts were determined by H2-TPR, TGA-DTG, the oxidation state of surface oxygen ions by XPS. It was found that at complete core coverage with perovskite shell, the distribution of surface oxygen species according to redox reactivity in CSM resemble pure LSF, but its lattice oxygen storage capacity is 2–2.5 times higher. At partial coverage, the distribution of surface oxygen species according to redox reactivity resembles that in iron oxide.}, number={23}, journal={MATERIALS}, publisher={MDPI AG}, author={Ohayon Dahan, Hen and Landau, Miron V. and Vidruk Nehemya, Roxana and Edri, Eran and Herskowitz, Moti and Ruan, Chongyan and Li, Fanxing}, year={2021}, month={Dec} }
 @article{brody_neal_haribal_li_2021, title={Ethane to liquids via a chemical looping approach - Redox catalyst demonstration and process analysis}, volume={417}, ISSN={["1873-3212"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85102136078&partnerID=MN8TOARS}, DOI={10.1016/j.cej.2021.128886}, abstractNote={The inability to economically transport ethane from distributed shale gas production sites results in the “rejection”, i.e. flaring or reinjection, of this important petrochemical feedstock. Therefore, a technology capable of efficiently converting geographically isolated ethane into transportable liquid fuels would effectively exploit this abundant yet wasted resource. We proposed a modular ethane-to-liquids (M−ETL) system that employs a chemical looping-oxidative dehydrogenation (CL-ODH) scheme to convert ethane into olefins via cyclic redox reactions. The olefins would subsequently undergo oligomerization to form mid-distillate liquid fuels. In this study, a sodium molybdate promoted CaTi0.1Mn0.9O3 core-shell redox catalyst (CaTi0.1Mn0.9O3@Na2MoO4) is presented as a potentially viable, redox-active catalyst for the CL-ODH of ethane to ethylene. Performance data were collected from 1,600 + hours (>4,000CL-ODH cycles) of packed bed operations at varying temperatures and space velocities. 52 – 58% single-pass olefin yields at 725 and 730 °C were obtained with relatively low (2.5 – 8%) COx selectivity. The experimental data were used as inputs to an ASPEN Plus® based M−ETL system model to evaluate its performance. Sensitivity analyses were performed on the CL-ODH and oligomerization sections of the M−ETL system, and the results were used to inform economic analysis of the process. The techno-economic analysis (TEA) indicates that the introduction of recycle to the system provides flexibility for profit generation for both high (Xethane = 0.75) and low (Xethane = 0.58) conversion cases. Additionally, TEA results demonstrate that electrical cogeneration can be economically attractive under certain scenarios.}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Brody, Leo and Neal, Luke and Haribal, Vasudev and Li, Fanxing}, year={2021}, month={Aug} }
 @article{iftikhar_jiang_gao_liu_gu_neal_li_2021, title={LaNixFe1-xO3-delta as a Robust Redox Catalyst for CO2 Splitting and Methane Partial Oxidation}, volume={35}, ISSN={["1520-5029"]}, DOI={10.1021/acs.energyfuels.1c02258}, abstractNote={The current study reports LaNi0.5Fe0.5O3−δ as a robust redox catalyst for CO2 splitting and methane partial oxidation at relatively low temperatures (∼700 °C) in the context of a hybrid redox process. Specifically, perovskite-structured LaNixFe1–xO3−δ (LNFs) with nine different compositions (x = 0.05–0.5) were prepared and investigated. Among the samples evaluated, LaNi0.4Fe0.6O3−δ and LaNi0.5Fe0.5O3−δ showed superior redox performance, with ∼90% CO2 and methane conversions and >90% syngas selectivity. The standalone LNFs also demonstrated performance comparable to that of LNF promoted by mixed conductive Ce0.85Gd0.1Cu0.05O2−δ (CGCO). Long-term testing of LaNi0.5Fe0.5O3−δ indicated that the redox catalyst gradually loses its activity over repeated redox cycles, amounting to approximately 0.02% activity loss each cycle, averaged over 500 cycles. This gradual deactivation was found to be reversible by deep oxidation with air. Further characterizations indicated that the loss of activity resulted from a slow accumulation of iron carbide (Fe3C and Fe5C2) phases, which cannot be effectively removed during the CO2 splitting step. Reoxidation with air removed the carbide phases, increased the availability of Fe for the redox reactions via solid-state reactions with La2O3, and decreased the average crystallite size of La2O3. Reactivating the redox catalyst periodically, e.g., once every 40 cycles, was shown to be highly effective, as confirmed by operating the redox catalyst over 900 cumulative cycles while maintaining satisfactory redox performance.}, number={17}, journal={ENERGY & FUELS}, author={Iftikhar, Sherafghan and Jiang, Qiongqiong and Gao, Yunfei and Liu, Junchen and Gu, Haiming and Neal, Luke and Li, Fanxing}, year={2021}, month={Sep}, pages={13921–13929} }
 @article{wang_gao_wang_cai_chung_iftikhar_wang_li_2021, title={Liquid Metal Shell as an Effective Iron Oxide Modifier for Redox-Based Hydrogen Production at Intermediate Temperatures}, volume={11}, ISSN={["2155-5435"]}, url={https://doi.org/10.1021/acscatal.1c02102}, DOI={10.1021/acscatal.1c02102}, abstractNote={This study reports molten metals (bismuth, indium, and tin) as effective modifiers for iron-based redox catalysts in the context of chemical looping-based hydrogen production at intermediate temperatures (450–650 °C) from low-calorific-value waste gas (e.g., blast furnace gas). The effects of the bismuth promoter on both the surface and bulk properties of iron oxides were studied in detail. Transmission electron microscopy and energy-dispersive spectroscopy (TEM-EDS), low-energy ion scattering (LEIS), Raman spectroscopy, and 18O2 exchange experiment revealed that the bismuth modifier forms an overlayer covering the bulk iron (oxides), leading to better anti-coking properties compared to reference La0.8Sr0.2FeO3- and Ce0.9Gd0.1O2-supported iron oxides. The Bi-modified sample also exhibited improved anti-sintering properties and high redox activity, resulting in a 4-fold increase in oxygen capacity compared to pristine Fe2O3 (28.9 vs 6.4 wt %) under a cyclic redox reaction at 550 °C. Meanwhile, a small amount of bismuth is doped into the iron oxide structure to effectively enhance its redox properties by lowering the oxygen vacancy formation energy (from 3.1 to 2.1 eV) and the energy barrier for vacancy migration, as confirmed by the experimental results and density functional theory (DFT) calculations. Reactive testing indicates that Bi-modified redox catalysts are highly active to convert low-calorific-value waste gases such as blast furnace gas. Our study also indicates that this strategy can be generalized to low-melting-point metals such as Bi, In, and Sn for iron oxide modification in chemical looping processes.}, number={16}, journal={ACS CATALYSIS}, publisher={American Chemical Society (ACS)}, author={Wang, Iwei and Gao, Yunfei and Wang, Xijun and Cai, Runxia and Chung, Chingchang and Iftikhar, Sherafghan and Wang, Wei and Li, Fanxing}, year={2021}, month={Aug}, pages={10228–10238} }
 @article{liu_gao_wang_li_2021, title={Molten-salt-mediated carbon dioxide capture and superequilibrium utilization with ethane oxidative dehydrogenation}, volume={2}, ISSN={["2666-3864"]}, DOI={10.1016/j.xcrp.2021.100503}, abstractNote={Existing CO2-mediated oxidative dehydrogenation (CO2-ODH) of ethane has yet to demonstrate >60% single-pass CO yield due to the intrinsic equilibrium limitations. We report a unique approach with mixed molten carbonates as a reaction medium for CO2-ODH, which strategically partitions the CO2-ODH reactions into gas and molten-salt phases and facilitates integrated CO2 capture from power plant flue gases. An 89% CO yield was achieved at 770°C, doubling the equilibrium limitation of conventional CO2-ODH. The high CO yield in turn enhances ethylene formation. Further characterizations confirmed that molten-salt mediated ODH (MM-ODH) proceeds through a gas-phase cracking and molten-salt mediated reverse water-gas-shift reaction pathway. Based on this understanding, thermodynamic analysis and ab initio molecular dynamics simulations were conducted to develop general principles to optimize the molten-salt reaction medium. Process analyses confirm that MM-ODH has the potential to be significantly more efficient for CO2 capture and utilization than conventional CO2-ODH.}, number={7}, journal={CELL REPORTS PHYSICAL SCIENCE}, author={Liu, Junchen and Gao, Yunfei and Wang, Xijun and Li, Fanxing}, year={2021}, month={Jul} }
 @article{wang_krzystowczyk_dou_li_2021, title={Net Electronic Charge as an Effective Electronic Descriptor for Oxygen Release and Transport Properties of SrFeO3-Based Oxygen Sorbents}, volume={33}, ISSN={["1520-5002"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85103753397&partnerID=MN8TOARS}, DOI={10.1021/acs.chemmater.0c04658}, abstractNote={Perovskite oxides, as oxygen sorbents, exhibit excellent potential in thermochemical redox applications such as chemical looping air separation (CLAS), resulting from their excellent redox properti...}, number={7}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Wang, Xijun and Krzystowczyk, Emily and Dou, Jian and Li, Fanxing}, year={2021}, month={Apr}, pages={2446–2456} }
 @article{han_zhou_wang_liu_xiong_zhang_gu_zhuang_zhang_li_et al._2021, title={One-step synthesis of single-site vanadium substitution in 1T-WS2 monolayers for enhanced hydrogen evolution catalysis}, volume={12}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-021-20951-9}, DOI={10.1038/s41467-021-20951-9}, abstractNote={Abstract Metallic tungsten disulfide (WS 2 ) monolayers have been demonstrated as promising electrocatalysts for hydrogen evolution reaction (HER) induced by the high intrinsic conductivity, however, the key challenges to maximize the catalytic activity are achieving the metallic WS 2 with high concentration and increasing the density of the active sites. In this work, single-atom-V catalysts (V SACs) substitutions in 1T-WS 2 monolayers (91% phase purity) are fabricated to significantly enhance the HER performance via a one-step chemical vapor deposition strategy. Atomic-resolution scanning transmission electron microscopy (STEM) imaging together with Raman spectroscopy confirm the atomic dispersion of V species on the 1T-WS 2 monolayers instead of energetically favorable 2H-WS 2 monolayers. The growth mechanism of V SACs@1T-WS 2 monolayers is experimentally and theoretically demonstrated. Density functional theory (DFT) calculations demonstrate that the activated V-atom sites play vital important role in enhancing the HER activity. In this work, it opens a novel path to directly synthesize atomically dispersed single-metal catalysts on metastable materials as efficient and robust electrocatalysts.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Han, Ali and Zhou, Xiaofeng and Wang, Xijun and Liu, Sheng and Xiong, Qihua and Zhang, Qinghua and Gu, Lin and Zhuang, Zechao and Zhang, Wenjing and Li, Fanxing and et al.}, year={2021}, month={Jan} }
 @article{ruan_wang_wang_li_lin_liu_li_wang_2021, title={Selective catalytic oxidation of ammonia to nitric oxide via chemical looping}, url={https://doi.org/10.21203/rs.3.rs-350833/v1}, DOI={10.21203/rs.3.rs-350833/v1}, abstractNote={Abstract Selective oxidation of ammonia to nitric oxide (NO) over platinum-group metal alloy gauzes is the crucial step for nitric acid production, a century-old yet greenhouse gas and capital intensive process in chemical industry. Therefore, developing alternative ammonia oxidation technologies with low environmental impacts and reduced catalyst cost are of significant importance. Herein, we proposed and demonstrated, for the first time, a novel chemical looping ammonia oxidation (CLAO) catalyst and process to replace the costly noble metal catalysts and to reduce greenhouse gas emission. The proposed CLAO process exhibited near complete NH 3 conversion and exceptional NO selectivity (99.8%) with negligible N 2 O production, using nonprecious V 2 O 5 redox catalyst at a temperature up to 300 °C lower than the existing approach. Operando spectroscopy techniques complemented with density functional theory calculations point towards a modified, temporally separated Mars-van Krevelen mechanism featuring a reversible V 5+ /V 4+ redox cycle. The V=O sites are suggested to be the catalytically active center leading to the formation of the oxidation products. Meanwhile, both V=O and doubly coordinated oxygen (V-O II -V) participate in the hydrogen transfer process. The outstanding performance is attributed to the low activation energies for the successive hydrogen abstraction (1.06 eV), facile NO formation (0.03 eV) as well as the easy regeneration of V=O species. Our results highlight a transformational CLAO process in extending the chemical looping strategy to producing base chemicals in a sustainable and cost-effective manner.}, author={Ruan, Chongyan and Wang, Xijun and Wang, Chaojie and Li, Lin and Lin, Jian and Liu, Xiao Yan and Li, Fanxing and Wang, Xiaodong}, year={2021}, month={Apr} }
 @article{dudek_li_2021, title={Selective hydrogen combustion as an effective approach for intensified chemical production via the chemical looping strategy}, volume={218}, ISSN={["1873-7188"]}, DOI={10.1016/j.fuproc.2021.106827}, abstractNote={Demand continues to grow rapidly for commodity chemicals, such as light olefins, at a time when the chemicals sector must strive to reduce its energy consumption and greenhouse gas emissions. Process intensification provides a framework for producing the same chemical products with higher efficiency and lower emissions. In recent years, chemical looping has received increasing attention as a strategy for intensified chemical production. For example, the chemical looping oxidative dehydrogenation (CL-ODH) of ethane to ethylene offers the potential for near order-of-magnitude reductions in process energy usage and CO2 emissions in comparison to conventional ethane steam cracking, while chemical looping dehydroaromatization (CL-DHA) of methane offers a pathway for aromatics production at higher yields. In these examples, the CL processes rely on selective hydrogen combustion (SHC) to remove the co-produced H2 gas as water, providing several benefits, including yield increase, autothermal operation, and simplified downstream separation. As a yield-enhancing strategy, SHC is not new. However, the design of redox catalysts for SHC in a chemical looping context has only recently begun to be explored. In this perspective, we summarize previous research on SHC in chemical production schemes, and we attempt to outline priority areas of research in the years to come.}, journal={FUEL PROCESSING TECHNOLOGY}, author={Dudek, Ryan B. and Li, Fanxing}, year={2021}, month={Jul} }
 @article{cai_li_2021, title={Tailoring the thermodynamic properties of complex oxides for thermochemical air separation and beyond}, volume={12}, journal={CIESC Journal}, author={Cai, Runxia and Li, Fanxing}, year={2021}, pages={6122–6130} }
 @article{hao_gao_liu_dudek_neal_wang_liu_li_2021, title={Zeolite-assisted core-shell redox catalysts for efficient light olefin production via cyclohexane redox oxidative cracking}, volume={409}, ISSN={["1873-3212"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85098692807&partnerID=MN8TOARS}, DOI={10.1016/j.cej.2020.128192}, abstractNote={This study reports a highly effective redox catalyst platform, i.e. composites of metal-exchanged ZSM5 and CaMn0.75Fe0.25O3@Na2WO4, for “low temperature” (<650 °C) redox oxidative cracking (ROC) of naphtha using a cyclohexane model compound. TEM-EDX showed that Na2WO4 shell covers the CaMn0.75Fe0.25O3 bulk and the zeolite + CaMn0.75Fe0.25O3@Na2WO4 composite can achieve autothermal conversion of cyclohexane under a cyclic redox scheme by selective oxidation of by-product H2 to H2O. Meanwhile, NH3-TPD and pyridine FTIR experiments confirmed that the Brönsted acidity of ZSM5 was primarily responsible for cyclohexane activation. Compared to each catalyst component alone, the synergistic effect of the composite redox catalysts resulted in substantially higher olefin yield (up to 75%), lower alkane yield (~5%), lower aromatic yield (~10%), and higher lattice oxygen utilization (up to 4 wt.cat%). Based on TGA-DSC experiments and ASPEN Plus analysis, the multi-functional redox catalysts facilitate autothermal conversion of cyclohexane with high lattice oxygen utilization from the redox catalysts. Due to the highly effective redox catalysts performance and the ease for heat integration, the novel ROC process has the potential for more energy-efficient light olefins production with significantly reduced CO2 emissions when compared to naphtha steam cracking.}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Hao, Fang and Gao, Yunfei and Liu, Junchen and Dudek, Ryan and Neal, Luke and Wang, Shuang and Liu, Pingle and Li, Fanxing}, year={2021}, month={Apr} }
 @article{gao_wang_liu_huang_zhao_zhao_wang_li_2020, title={A molten carbonate shell modified perovskite redox catalyst for anaerobic oxidative dehydrogenation of ethane}, volume={6}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.aaz9339}, DOI={10.1126/sciadv.aaz9339}, abstractNote={Molten carbonate leads to a 10-fold ethylene yield increase by facilitating oxygen transport while blocking nonselective sites.}, number={17}, journal={SCIENCE ADVANCES}, publisher={American Association for the Advancement of Science (AAAS)}, author={Gao, Yunfei and Wang, Xijun and Liu, Junchen and Huang, Chuande and Zhao, Kun and Zhao, Zengli and Wang, Xiaodong and Li, Fanxing}, year={2020}, month={Apr} }
 @article{dou_krzystowczyk_wang_robbins_ma_liu_li_2020, title={A- and B-site Codoped SrFeO3 Oxygen Sorbents for Enhanced Chemical Looping Air Separation}, volume={13}, ISSN={["1864-564X"]}, url={https://doi.org/10.1002/cssc.201902698}, DOI={10.1002/cssc.201902698}, abstractNote={Abstract}, number={2}, journal={CHEMSUSCHEM}, publisher={Wiley}, author={Dou, Jian and Krzystowczyk, Emily and Wang, Xijun and Robbins, Thomas and Ma, Liang and Liu, Xingbo and Li, Fanxing}, year={2020}, month={Jan}, pages={385–393} }
 @article{zhang_mao_zhang_tian_sullivan_cao_zeng_li_hu_2020, title={CO2 Reforming of Ethanol: Density Functional Theory Calculations, Microkinetic Modeling, and Experimental Studies}, volume={10}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85089995954&partnerID=MN8TOARS}, DOI={10.1021/acscatal.9b05231}, abstractNote={Ethanol dry reformation (EDR) is a chemical process for syngas production, which consumes a greenhouse gas and reduces carbon footprint. We present a mechanistic study of EDR over Rh catalyst based...}, number={16}, journal={ACS CATALYSIS}, author={Zhang, Jia and Mao, Yu and Zhang, Junshe and Tian, Junfu and Sullivan, Michael B. and Cao, X-M and Zeng, Yingzhi and Li, Fanxing and Hu, P.}, year={2020}, month={Aug}, pages={9624–9633} }
 @misc{zhu_imtiaz_donat_mueller_li_2020, title={Chemical looping beyond combustion - a perspective}, volume={13}, ISSN={["1754-5706"]}, url={https://doi.org/10.1039/C9EE03793D}, DOI={10.1039/c9ee03793d}, abstractNote={Facilitated by redox catalysts capable of catalytic reactions and reactive separation, chemical looping offers exciting opportunities for intensified chemical production.}, number={3}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, publisher={Royal Society of Chemistry (RSC)}, author={Zhu, Xing and Imtiaz, Qasim and Donat, Felix and Mueller, Christoph R. and Li, Fanxing}, year={2020}, month={Mar}, pages={772–804} }
 @article{campbell_jackson_lustik_al-rashdi_bennett_li_abolhasani_2020, title={Continuous flow synthesis of phase transition-resistant titania microparticles with tunable morphologies}, volume={10}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081120029&partnerID=MN8TOARS}, DOI={10.1039/d0ra01442g}, abstractNote={A flow chemistry strategy for synthesis of anatase titania microparticles utilizing a flow-focusing microreactor integrated with a collimated UV LED is presented. The synthesized microparticles possess a wide variety of morphologies and high surface areas (up to 362 m2 g−1).}, number={14}, journal={RSC Advances}, author={Campbell, Zachary S. and Jackson, Daniel and Lustik, Jacob and Al-Rashdi, Amur K. and Bennett, Jeffrey A. and Li, Fanxing and Abolhasani, Milad}, year={2020}, pages={8340–8347} }
 @article{tian_dudek_westmoreland_li_2020, title={Effect of Sodium Tungstate Promoter on the Reduction Kinetics of CaMn0.9Fe0.1O3 for Chemical Looping - Oxidative Dehydrogenation of Ethane}, volume={398}, ISSN={["1873-3212"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85085392858&partnerID=MN8TOARS}, DOI={10.1016/j.cej.2020.125583}, abstractNote={Reduction kinetics of unpromoted and Na2WO4-promoted CaMn0.9Fe0.1O3 redox catalysts are measured in the context of chemical looping-oxidative dehydrogenation (CL-ODH). CL-ODH is a promising alternative for ethylene production compared to steam cracking, as it reduces the energy demand and increases the single-pass ethane conversion. The ability of a redox catalyst for selective hydrogen combustion (SHC), i.e. selectively oxidizing hydrogen co-product from ethane dehydrogenation, represents an effective strategy for CL-ODH because it can shift the reaction equilibrium and facilitate exothermic overall reaction. In this work, kinetic models and parameters of unpromoted and Na2WO4-promoted, Fe-doped CaMnO3 (CaMn0.9Fe0.1O3) under H2 and C2H4 were investigated. The reduction of unpromoted CaMn0.9Fe0.1O3 follows reaction-order models. C2H4 reduction has a higher energy barrier and a greater dependence on active lattice oxygen concentration, resulting in an order-of-magnitude decrease in the reduction rate. In comparison, the reduction of Na2WO4-promoted CaMn0.9Fe0.1O3 follows an Avrami-Erofe’ev nucleation and nuclei growth model. The addition of Na2WO4 more significantly suppressed C2H4 combustion relative to H2 oxidation. As a result, the reduction rate of Na2WO4-promoted CaMn0.9Fe0.1O3 under H2 was three orders of magnitude greater than that under C2H4, demonstrating its excellent SHC properties. The resulting redox catalyst was shown to be effective for ethane CL-ODH with measured 90.5% ethylene selectivity and 41.6% ethylene yield at 750 °C. The kinetics models and parameters provide useful information for CL-ODH reactor design and further development of the redox catalyst.}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Tian, Yuan and Dudek, Ryan B. and Westmoreland, Phillip R. and Li, Fanxing}, year={2020}, month={Oct} }
 @article{zheng_liao_xiao_haribal_shi_huang_zhu_li_li_wang_et al._2020, title={Highly efficient reduction of O-2-containing CO2 via chemical looping based on perovskite nanocomposites}, volume={78}, ISSN={["2211-3282"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85090554382&partnerID=MN8TOARS}, DOI={10.1016/j.nanoen.2020.105320}, abstractNote={Purification/separation of CO2 stream from carbon capture or other carbon source is highly energy consuming process. However, oxidative impurity of O2 either deactivates catalysts in most carbon reduction systems, and thus reduces CO2 conversion efficiency. Here we report an effective method for splitting O2-containing CO2 into CO, through a chemical looping scheme with Cu (5 at%) doped LaFeO3 perovskites as efficient oxygen carriers. Up to 2.28 mol/kg CO yield was achieved with high stability in the presence of O2, five times higher than that with the state-of-the-art oxygen carrier, while pristine LaFeO3 perovskite only showed efficient capability of reducing pure CO2. Furthermore, the syngas productivity was doubled with Cu modification. Through experimental characterizations and ab initio calculations, we uncovered that the exsolution of metallic Cu on the surface of reduced perovskite was able to mitigate the competition between CO2 and O2 in the re-oxidation step. We envision that the efficient CO2 splitter with well-designed oxygen carriers have the potential to facilitate economical combination of impure carbon feedstock and carbon utilization system.}, journal={NANO ENERGY}, author={Zheng, Yan'e and Liao, Xiangbiao and Xiao, Hang and Haribal, Vasudev and Shi, Xiaoyang and Huang, Zhen and Zhu, Liangliang and Li, Kongzhai and Li, Fanxing and Wang, Hua and et al.}, year={2020}, month={Dec} }
 @article{huang_zheng_deng_wei_zhao_chen_he_zhao_li_li_2020, title={In-situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier}, volume={190}, ISSN={["1873-6785"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85074347561&partnerID=MN8TOARS}, DOI={10.1016/j.energy.2019.116360}, abstractNote={Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.}, journal={ENERGY}, author={Huang, Zhen and Zheng, Anqing and Deng, Zhengbing and Wei, Guoqiang and Zhao, Kun and Chen, Dezhen and He, Fang and Zhao, Zengli and Li, Haibin and Li, Fanxing}, year={2020}, month={Jan} }
 @article{jiang_gao_haribal_qi_liu_hong_jin_li_2020, title={Mixed conductive composites for 'Low-Temperature' thermo-chemical CO(2)splitting and syngas generation}, volume={8}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/D0TA03232H}, DOI={10.1039/d0ta03232h}, abstractNote={An effective strategy to design platinum group metal (PGM) free redox catalysts for “low temperature” CO2 splitting followed with methane partial oxidation was proposed and validated.}, number={26}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Jiang, Qiongqiong and Gao, Yunfei and Haribal, Vasudev Pralhad and Qi, He and Liu, Xingbo and Hong, Hui and Jin, Hongguang and Li, Fanxing}, year={2020}, month={Jul}, pages={13173–13182} }
 @article{novotny_yusuf_li_lamb_2020, title={MoO3/Al2O3 catalysts for chemical-looping oxidative dehydrogenation of ethane}, volume={152}, ISSN={["1089-7690"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85078845301&partnerID=MN8TOARS}, DOI={10.1063/1.5135920}, abstractNote={MoO3/γ-Al2O3 catalysts containing 0.3–3 monolayer (ML) equivalents of MoO3 were prepared, characterized, and tested for ethane oxidative dehydrogenation (ODH) in cyclic redox and co-feed modes. Submonolayer catalysts contain highly dispersed (2D) polymolybdate structures; a complete monolayer and bulk Al2(MoO4)3 are present at >1ML loadings. High ethylene selectivity (>90%) in chemical looping (CL) ODH correlates with Mo+VI to Mo+V reduction; COx selectivity is <10% under these conditions. Mo+V and Mo+IV species trigger CH4 production resulting in much higher conversion albeit with <20% selectivity. In CL-ODH, submonolayer catalysts exhibit ethylene selectivities that decrease linearly from 96% at near-zero conversion to 70% at 45% conversion. >1ML catalysts provide higher conversions albeit with 10%–18% lower selectivity and greater selectivity loss with increasing conversion. In co-feed mode, ethylene selectivity drops to <50% at 46% conversion for a 0.6ML catalyst, but selectivity is virtually unaltered for a 3ML catalyst. We infer that at <1ML loadings, small domain size and strong Mo—O—Al bonds decrease 2D polymolybdate reducibility and enhance ethylene selectivity in CL-ODH.}, number={4}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Novotny, Petr and Yusuf, Seif and Li, Fanxing and Lamb, H. Henry}, year={2020}, month={Jan} }
 @inbook{gao_li_2020, title={Natural Gas Conversion to Olefins via Chemical Looping}, ISBN={9780429022852}, url={http://dx.doi.org/10.1201/9780429022852-4}, DOI={10.1201/9780429022852-4}, booktitle={Direct Natural Gas Conversion to Value-Added Chemicals}, publisher={CRC Press}, author={Gao, Yunfei and Li, Fanxing}, year={2020}, month={Sep}, pages={71–94} }
 @article{dudek_tian_jin_blivin_li_2020, title={Reduction Kinetics of Perovskite Oxides for Selective Hydrogen Combustion in the Context of Olefin Production}, volume={8}, ISSN={["2194-4296"]}, url={https://doi.org/10.1002/ente.201900738}, DOI={10.1002/ente.201900738}, abstractNote={Chemical looping represents a novel approach for generating light olefins in which thermal cracking or catalytic dehydrogenation is coupled with selective hydrogen combustion (SHC) by a metal oxide redox catalyst, which enables autothermal operation, increased per‐pass conversion, and greater‐than‐equilibrium yields. Recent studies indicate that Na2WO4‐promoted perovskite oxides are effective redox catalysts with high olefin selectivity. Herein, kinetic parameters, rates, and reaction models for the reduction of unpromoted and Na2WO4‐promoted CaMnO3 redox catalysts by H2, C2H4, and C2H6, is reported. Reduction rates of CaMnO3 under ethylene and ethane are significantly lower than under H2. Model fitting of reduction kinetics show good agreement with reaction order–controlled models for CaMnO3 reduction and predict greater oxygen site dependence and higher activation energy for CaMnO3 reduction by C2H4 as compared with H2. Avrami–Erofe'ev nucleation and growth models provide the best fit to the reduction of Na2WO4/CaMnO3 in H2 and in C2H4. After Na2WO4 promotion, the reduction rate of CaMnO3 is three orders of magnitude lower in ethylene in comparison to hydrogen, consistent with its superior selectivity to hydrogen combustion. The models developed can be applied toward reactor design and optimization in the context of enhanced olefin production via SHC under a cyclic redox scheme.}, number={8}, journal={ENERGY TECHNOLOGY}, publisher={Wiley}, author={Dudek, Ryan B. and Tian, Yuan and Jin, Gaochen and Blivin, Millicent and Li, Fanxing}, year={2020}, month={Aug} }
 @article{mishra_shafiefarhood_dou_li_2020, title={Rh promoted perovskites for exceptional ?low temperature? methane conversion to syngas}, volume={350}, ISSN={["1873-4308"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065818713&partnerID=MN8TOARS}, DOI={10.1016/j.cattod.2019.05.036}, abstractNote={By utilizing lattice oxygen of a reducible metal oxide (a.k.a. redox catalyst), chemical looping reforming (CLR) partially oxidizes methane to syngas without gaseous oxygen. Subsequent to methane partial oxidation (POx), the reduced metal oxide is re-oxidized with air to complete the two-step redox cycle. In essence, CLR accomplishes methane POx without the need for an air separation unit, offering a potentially more efficient route for syngas production. This study investigates Rh promoted and iron/strontium doped CaMnO3 as redox catalysts at relatively low temperatures (<700 °C). These redox catalysts takes advantage of Rh promoter for methane activation as well as the high redox activity of iron/strontium doped CaMnO3. It was determined that Sr and Fe doped CaMnO3 are highly active for methane conversion, showing lattice oxygen extraction of 2.2–4.5 wt.% at 600 °C. However, the syngas selectivities are relatively low, with Sr doped CaMnO3 redox catalysts showing syngas selectivity ˜50% and Fe doped CaMnO3 doped redox catalysts showing syngas selectivity less than 5%. To further increase the syngas selectivity and yield, a reforming catalyst was placed downstream of the chemical looping bed. Under such a sequential bed scheme, 88–96% syngas selectivity was demonstrated for the redox catalysts. Optimization of the reaction conditions showed that a sequential bed composed of Rh promoted CaMn0.75Fe0.25O3 with a downstream reforming catalyst bed is capable of achieving syngas yields above 70% at 600 °C. The relatively low operating temperature and elimination of air separation unit make the redox catalysts and the sequential bed scheme a potentially attractive option for methane conversion.}, journal={CATALYSIS TODAY}, author={Mishra, Amit and Shafiefarhood, Arya and Dou, Jian and Li, Fanxing}, year={2020}, month={Jun}, pages={149–155} }
 @article{hao_gao_neal_dudek_li_chung_guan_liu_liu_li_2020, title={Sodium tungstate-promoted CaMnO3 as an effective, phase-transition redox catalyst for redox oxidative cracking of cyclohexane}, volume={385}, ISSN={["1090-2694"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85082646635&partnerID=MN8TOARS}, DOI={10.1016/j.jcat.2020.03.022}, abstractNote={Oxidative cracking, which combines catalytic oxidation and cracking reactions, represents a promising approach to reduce the energy and carbon intensities for light olefin production from naphtha. The need to co-feed gaseous oxygen with hydrocarbons, however, leads to significant COx formation and safety concerns. The cost and energy consumption associated with air separation also affects its economic attractiveness. In this study, we investigated a redox oxidative cracking (ROC) scheme and evaluated perovskites (La0.8Sr0.2FeO3 and CaMnO3) and Na2WO4-promoted perovskite (La0.8Sr0.2FeO3@Na2WO4 and CaMnO3@Na2WO4) as the redox catalysts for ROC. CaMnO3@Na2WO4 redox catalyst shows high activity, selectivity, and stability for light olefin production from cyclohexane. Operated under a redox oxidative cracking (ROC) scheme, CaMnO3@Na2WO4 enhances the catalytic cracking of cyclohexane, while showing high selectivity towards hydrogen combustion with its built-in, active lattice oxygen. Over three-fold increase in olefin yield compared to thermal cracking and 35% yield increase compared to conventional O2-cofeed oxidative cracking were achieved. Low energy ion scattering (LEIS), X-ray photoelectric spectroscopy (XPS), and differential scanning calorimetry (DSC) indicated a core-shell structure, where a molten Na2WO4 layer covers the CaMnO3 core. Na2WO4 modifies the oxygen donation behavior of CaMnO3 and provides a catalytically active surface for cyclohexane activation. In-situ XRD revealed that CaMnO3@Na2WO4 exhibited excellent structural stability and regenerability. The transformation of Mn4+ ↔ Mn3+ ↔ Mn2+ in CaMnO3, facilitated by reversible phase transition to (Ca/Mn)O solid solution, is responsible for the lattice oxygen donation and uptake during redox cycles. Electrochemical impedance spectroscopy (EIS) measurements further confirmed that the oxygen species were transported through the molten Na2WO4 layer to participate in ROC. These findings offer mechanistic insights to design effective redox catalysts for hydrocarbon valorization using the chemical looping strategy.}, journal={JOURNAL OF CATALYSIS}, author={Hao, Fang and Gao, Yunfei and Neal, Luke and Dudek, Ryan B. and Li, Wenyuan and Chung, Chingchang and Guan, Bo and Liu, Pingle and Liu, Xingbo and Li, Fanxing}, year={2020}, month={May}, pages={213–223} }
 @article{dou_krzystowczyk_wang_richard_robbins_li_2020, title={Sr1-xCaxFe1-yCoyO3-delta as facile and tunable oxygen sorbents for chemical looping air separation}, volume={2}, ISSN={["2515-7655"]}, url={https://doi.org/10.1088/2515-7655/ab7cb0}, DOI={10.1088/2515-7655/ab7cb0}, abstractNote={Chemical looping air separation (CLAS) is a promising technology for oxygen generation with high efficiency. The key challenge for CLAS is to design robust oxygen sorbents with suitable redox properties and fast redox kinetics. In this work, perovskite-structured Sr1-xCaxFe1-yCoyO3 oxygen sorbents were investigated and demonstrated for oxygen production with tunable redox properties, high redox rate, and excellent thermal/steam stability. Cobalt doping at B site was found to be highly effective, 33% improvement in oxygen productivity was observed at 500 °C. Moreover, it stabilizes the perovskite structure and prevents phase segregation under pressure swing conditions in the presence of steam. Scalable synthesis of Sr0.8Ca0.2Fe0.4Co0.6O3 oxygen sorbents was carried out through solid state reaction, co-precipitation, and sol-gel methods. Both co-precipitation and sol-gel methods are capable of producing Sr0.8Ca0.2Fe0.4Co0.6O3 sorbents with satisfactory phase purity, high oxygen capacity, and fast redox kinetics. Large scale evaluation of Sr0.8Ca0.2Fe0.4Co0.6O3, using an automated CLAS testbed with over 300 g sorbent loading, further demonstrated the effectiveness of the oxygen sorbent to produce 95% pure O2 with a satisfactory productivity of 0.04 gO2 gsorbent−1 h−1 at 600 °C.}, number={2}, journal={JOURNAL OF PHYSICS-ENERGY}, publisher={IOP Publishing}, author={Dou, Jian and Krzystowczyk, Emily and Wang, Xijun and Richard, Anthony R. and Robbins, Thomas and Li, Fanxing}, year={2020}, month={Apr} }
 @article{krzystowczyk_wang_dou_haribal_li_2020, title={Substituted SrFeO3 as robust oxygen sorbents for thermochemical air separation: correlating redox performance with compositional and structural properties}, volume={22}, url={https://doi.org/10.1039/D0CP00275E}, DOI={10.1039/D0CP00275E}, abstractNote={Quantification of the dopant effect on SrFeO3 provides a potentially effective strategy for developing improved sorbents for thermochemical air separation.}, number={16}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Krzystowczyk, Emily and Wang, Xijun and Dou, Jian and Haribal, Vasudev and Li, Fanxing}, year={2020}, pages={8924–8932} }
 @article{gao_wang_hao_dai_li_2020, title={Zeolite-Perovskite Composites as Effective Redox Catalysts for Autothermal Cracking of n-Hexane}, volume={8}, ISSN={["2168-0485"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85094838280&partnerID=MN8TOARS}, DOI={10.1021/acssuschemeng.0c04207}, abstractNote={This study reports highly effective, multifunctional ZSM5/CaMnO3@Na2WO4 composite redox catalysts for redox oxidative cracking (ROC) of n-hexane. Compared to the previously reported redox catalysts...}, number={38}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Gao, Yunfei and Wang, Shuang and Hao, Fang and Dai, Zijian and Li, Fanxing}, year={2020}, month={Sep}, pages={14268–14273} }
 @article{dai_gu_tian_wu_chen_li_du_peng_ding_yang_2020, title={gamma-Al2O3 sheet-stabilized isolate Co2+ for catalytic propane dehydrogenation}, volume={381}, ISSN={["1090-2694"]}, url={https://doi.org/10.1016/j.jcat.2019.11.026}, DOI={10.1016/j.jcat.2019.11.026}, abstractNote={Co-based catalysts are promising alternatives to replace Pt- and Cr-based catalysts for propane dehydrogenation (PDH) in view of the catalytic activity for C–H bond activation, low cost, and low toxicity. However, the reduction of unstable CoOx species and coke deposition cause serious catalyst deactivation. In this work, a sheet-shaped Co–Al2O3 catalyst comprising of isolate Co2+ sites shows a high intrinsic activity (specific reaction rate > 16 mmol g−1 h−1) and catalytic stability in highly selective PDH reaction (>97% C3H6 selectivity). Extensive characterization demonstrates that the tetrahedral Co2+ isolated site is stabilized by the γ-Al2O3 matrix, facilitating propylene desorption to inhibit formation of coke and other byproducts and to free the active Co sites.}, journal={JOURNAL OF CATALYSIS}, publisher={Elsevier BV}, author={Dai, Yihu and Gu, Jingjing and Tian, Suyang and Wu, Yue and Chen, Junchao and Li, Fanxing and Du, Yonghua and Peng, Luming and Ding, Weiping and Yang, Yanhui}, year={2020}, month={Jan}, pages={482–492} }
 @article{yusuf_neal_bao_wu_li_2019, title={Effects of Sodium and Tungsten Promoters on Mg6MnO8-Based Core-Shell Redox Catalysts for Chemical Looping-Oxidative Dehydrogenation of Ethane}, volume={9}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85064004480&partnerID=MN8TOARS}, DOI={10.1021/acscatal.9b00164}, abstractNote={The present study investigates the effect of sodium and tungsten promoters on Mg6MnO8-based redox catalysts in a chemical looping oxidative dehydrogenation (CL-ODH) scheme. CL-ODH has the potential...}, number={4}, journal={ACS CATALYSIS}, author={Yusuf, Seif and Neal, Luke and Bao, Zhenghong and Wu, Zili and Li, Fanxing}, year={2019}, month={Apr}, pages={3174–3186} }
 @article{neal_haribal_li_2019, title={Intensified Ethylene Production via Chemical Looping through an Exergetically Efficient Redox Scheme}, volume={19}, ISSN={["2589-0042"]}, url={https://doi.org/10.1016/j.isci.2019.08.039}, DOI={10.1016/j.isci.2019.08.039}, abstractNote={Ethylene production via steam cracking of ethane and naphtha is one of the most energy and emission-intensive processes in the chemical industry. High operating temperatures, significant reaction endothermicity, and complex separations create hefty energy demands and result in substantial CO2 and NOx emissions. Meanwhile, decades of optimization have led to a thermally efficient, near-"perfect" process with ∼95% first law energy efficiency, leaving little room for further reduction in energy consumption and CO2 emissions. In this study, we demonstrate a transformational chemical looping-oxidative dehydrogenation (CL-ODH) process that offers 60%-87% emission reduction through exergy optimization. Through detailed exergy analyses, we show that CL-ODH leads to exergy savings of up to 58% in the upstream reactors and 26% in downstream separations. The feasibility of CL-ODH is supported by a robust redox catalyst that demonstrates stable activity and selectivity for over 1,400 redox cycles in a laboratory-scale fluidized bed reactor.}, journal={ISCIENCE}, publisher={Elsevier BV}, author={Neal, Luke M. and Haribal, Vasudev Pralhad and Li, Fanxing}, year={2019}, month={Sep}, pages={894-+} }
 @article{yusuf_haribal_jackson_neal_li_2019, title={Mixed iron-manganese oxides as redox catalysts for chemical looping-oxidative dehydrogenation of ethane with tailorable heat of reactions}, volume={257}, ISSN={["1873-3883"]}, url={https://doi.org/10.1016/j.apcatb.2019.117885}, DOI={10.1016/j.apcatb.2019.117885}, abstractNote={The chemical looping-oxidative dehydrogenation (CL-ODH) of ethane is investigated in this study. In CL-ODH, a redox catalyst donates its lattice oxygen to combust hydrogen formed from ethane dehydrogenation (ODH reactor). The reduced redox catalyst is then transferred to a separate reactor (regenerator), where it is re-oxidized with air. Typically, the ODH step is endothermic, due to the high endothermicity to reduce the redox catalyst. This energy demand is met through sensible heat carried by the redox catalyst from the regenerator, which operates at a higher temperature. This temperature difference between the two reactors leads to exergy losses. We report an Fe-Mn redox catalyst showing tunable exothermic heat of reduction. Promotion with Na2WO4 resulted in high ethylene yields due to the suppression of surface Fe/Mn. ASPEN Plus® simulations indicated that Fe-Mn redox catalysts can lower the temperature difference between the two reactors. This can lead to efficiency improvements for CL-ODH.}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, publisher={Elsevier BV}, author={Yusuf, Seif and Haribal, Vasudev and Jackson, Daniel and Neal, Luke and Li, Fanxing}, year={2019}, month={Nov} }
 @article{haribal_wang_dudek_paulus_turk_gupta_li_2019, title={Modified Ceria for "Low-Temperature" CO2 Utilization: A Chemical Looping Route to Exploit Industrial Waste Heat}, volume={9}, ISSN={["1614-6840"]}, url={https://doi.org/10.1002/aenm.201901963}, DOI={10.1002/aenm.201901963}, abstractNote={Abstract}, number={41}, journal={ADVANCED ENERGY MATERIALS}, publisher={Wiley}, author={Haribal, Vasudev Pralhad and Wang, Xijun and Dudek, Ryan and Paulus, Courtney and Turk, Brian and Gupta, Raghubir and Li, Fanxing}, year={2019}, month={Nov} }
 @article{neal_haribal_mccaig_lamb_li_2019, title={Modular‐scale ethane to liquids via chemical looping oxidative dehydrogenation: Redox catalyst performance and process analysis}, volume={1}, ISSN={2637-403X 2637-403X}, url={http://dx.doi.org/10.1002/AMP2.10015}, DOI={10.1002/AMP2.10015}, abstractNote={Abstract}, number={1-2}, journal={Journal of Advanced Manufacturing and Processing}, publisher={Wiley}, author={Neal, Luke and Haribal, Vasudev and McCaig, Joseph and Lamb, H. Henry and Li, Fanxing}, year={2019}, month={Apr}, pages={e10015} }
 @article{mishra_li_li_santiso_2019, title={Oxygen Vacancy Creation Energy in Mn-Containing Perovskites: An Effective Indicator for Chemical Looping with Oxygen Uncoupling}, volume={31}, ISSN={["1520-5002"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85061650487&partnerID=MN8TOARS}, DOI={10.1021/acs.chemmater.8b03187}, abstractNote={Chemical looping with oxygen uncoupling (CLOU) is a novel process for carbon dioxide capture from coal combustion. Designing a metal oxide oxygen carrier with suitable oxygen release and uptake (redox) properties represents one of the most critical aspects for CLOU. The current work aims to correlate oxygen vacancy creation energy of metal oxide oxygen carriers with their redox properties. Oxygen vacancy creation energies of CaMnO3−δ, Ca0.75Sr0.25MnO3−δ, CaMn0.75Fe0.25O3−δ, and BaMnO3−δ were determined through density functional theory (DFT) calculations. The effect of the Hubbard U correction on the ground state magnetic configurations and vacancy creation energies was investigated, along with the effect of lattice oxygen coordination environment. It was determined that Hubbard U only slightly changes the relative differences in vacancy creation energies between the Mn-containing perovskites investigated. Therefore, ranking of oxygen vacancy creation energies among the various oxides can be determined us...}, number={3}, journal={CHEMISTRY OF MATERIALS}, author={Mishra, Amit and Li, Tianyang and Li, Fanxing and Santiso, Erik E.}, year={2019}, month={Feb}, pages={689–698} }
 @article{dudek_tian_blivin_neal_zhao_li_2019, title={Perovskite oxides for redox oxidative cracking of n-hexane under a cyclic redox scheme}, volume={246}, ISSN={["1873-3883"]}, url={https://doi.org/10.1016/j.apcatb.2019.01.048}, DOI={10.1016/j.apcatb.2019.01.048}, abstractNote={Steam cracking of naphtha is a commercially proven technology for light olefin production and the primary source of ethylene in the Europe and Asia-Pacific markets. However, its significant energy consumption and high CO2 intensity (up to 2 tons CO2/ton C2H4), stemming from endothermic cracking reactions and complex product separations, make this state-of-the-art process increasingly undesirable from an environmental standpoint. We propose a redox oxidative cracking (ROC) approach as an alternative pathway for naphtha conversion. Enabled by perovskite oxide-based redox catalysts, the ROC process converts naphtha (represented by n-hexane) in an auto-thermal, cyclic redox mode. The addition of 20 wt.% Na2WO4 to SrMnO3 and CaMnO3 created highly selective redox catalysts capable of achieving enhanced olefin yields from n-hexane oxy-cracking. This was largely attributed to the redox catalysts’ high activity, selectivity, and stability towards selective hydrogen combustion (SHC) under a redox mode. Na2WO4/CaMnO3 demonstrated significantly higher olefin yield (55–58%) when compared to that from thermal cracking (34%) at 725 °C and 4500 h−1. COx yield as low as 1.7% was achieved along with complete combustion of H2 over 25 cycles. Similarly, Na2WO4/SrMnO3 achieved 41% olefin yield, 0.4% COx yield, and 73% H2 combustion at this condition. Oxygen-temperature-programmed desorption (O2-TPD) indicated that Na2WO4 hindered gaseous oxygen release from CaMnO3. Low-energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) revealed an outermost perovskite surface layer covered by Na2WO4, which suppressed near-surface Mn and alkaline earth metal cations. The formation of non-selective surface oxygen species was also inhibited. XPS analysis further confirmed that promotion of SrMnO3 with Na2WO4 suppressed surface Sr species by 90%, with a similar effect also observed on CaMnO3. These findings point to the promoting effect of Na2WO4 and the potential of promoted SrMnO3 and CaMnO3 as selective redox catalysts for efficient production of light olefins from naphtha via the ROC process.}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, publisher={Elsevier BV}, author={Dudek, Ryan B. and Tian, Xin and Blivin, Millicent and Neal, Luke M. and Zhao, Haibo and Li, Fanxing}, year={2019}, month={Jun}, pages={30–40} }
 @misc{gao_neal_ding_wu_baroi_gaffney_li_2019, title={Recent Advances in Intensified Ethylene Production-A Review}, volume={9}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071911366&partnerID=MN8TOARS}, DOI={10.1021/acscatal.9b02922}, abstractNote={Steam cracking is a well-established commercial technology for ethylene production. Despite decades of optimization efforts, the process is, nevertheless, highly energy and carbon intensive. This r...}, number={9}, journal={ACS CATALYSIS}, author={Gao, Yunfei and Neal, Luke and Ding, Dong and Wu, Wei and Baroi, Chinmoy and Gaffney, Anne M. and Li, Fanxing}, year={2019}, month={Sep}, pages={8592–8621} }
 @article{tian_dudek_gao_zhao_li_2019, title={Redox oxidative cracking of n-hexane with Fe-substituted barium hexaaluminates as redox catalysts}, volume={9}, ISSN={["2044-4761"]}, url={https://doi.org/10.1039/C8CY02530D}, DOI={10.1039/c8cy02530d}, abstractNote={Promoted hexaaluminate redox catalysts achieved excellent olefin yield while allowing autothermal redox oxidative cracking of naphtha with low COx formation.}, number={9}, journal={CATALYSIS SCIENCE & TECHNOLOGY}, publisher={Royal Society of Chemistry (RSC)}, author={Tian, Xin and Dudek, Ryan B. and Gao, Yunfei and Zhao, Haibo and Li, Fanxing}, year={2019}, month={May}, pages={2211–2220} }
 @article{gao_haeri_he_li_2018, title={Alkali Metal-Promoted LaxSr2-xFeO4-delta Redox Catalysts for Chemical Looping Oxidative Dehydrogenation of Ethane}, volume={8}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042879284&partnerID=MN8TOARS}, DOI={10.1021/acscatal.7b03928}, abstractNote={Chemical looping oxidative dehydrogenation (CL-ODH) represents a redox approach to convert ethane into ethylene under an autothermal scheme. Instead of using gaseous oxygen, CL-ODH utilizes lattice oxygen in transition metal oxides, which acts as an oxygen carrier or redox catalyst, to facilitate the ODH reaction. The oxygen-deprived redox catalyst is subsequently regenerated with air and releases heat. The current study investigated alkali metal (Li, Na, and/or K)-promoted LaxSr2–xFeO4−δ (LaSrFe) as redox catalysts for CL-ODH of ethane. While unpromoted LaSrFe exhibited poor ethylene selectivity, addition of Na or K promoter achieved up to 61% ethane conversion and 68% ethylene selectivity at 700 °C. The promotional effect of K on LaSrFe was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low-energy ion scattering spectroscopy (LEIS), transmission electron microscopy (TEM), O2-temperature-programmed desorption (TPD), H2-temperature-programmed reduction (TPR), and 18O2...}, number={3}, journal={ACS CATALYSIS}, author={Gao, Yunfei and Haeri, Farrah and He, Fang and Li, Fanxing}, year={2018}, month={Mar}, pages={1757–1766} }
 @article{dang_li_yusuf_cao_wang_yu_peng_li_2018, title={Calcium cobaltate: a phase-change catalyst for stable hydrogen production from bio-glycerol}, volume={11}, ISSN={["1754-5706"]}, url={https://doi.org/10.1039/C7EE03301J}, DOI={10.1039/c7ee03301j}, abstractNote={Layered calcium cobaltates exhibit a very stable performance in SESR of glycerol producing hydrogen because of a reversible phase change.}, number={3}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, publisher={Royal Society of Chemistry (RSC)}, author={Dang, Chengxiong and Li, Yuhang and Yusuf, Seif M. and Cao, Yonghai and Wang, Hongjuan and Yu, Hao and Peng, Feng and Li, Fanxing}, year={2018}, month={Mar}, pages={660–668} }
 @misc{mishra_li_2018, title={Chemical looping at the nanoscale - challenges and opportunities}, volume={20}, ISSN={["2211-3398"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85047404801&partnerID=MN8TOARS}, DOI={10.1016/j.coche.2018.05.001}, abstractNote={The activity and long-term performance of oxygen carrier particles, which undergo cyclic reduction–oxidation (redox) reactions at elevated temperatures, are of critical importance to chemical looping processes. Although the significant thermal and redox stresses in chemical looping reaction make it challenging to stabilize metal oxide based oxygen carriers at the nanoscale, a number of promising approaches have been proposed and investigated over the past decade. This article summarizes recent advances in nanoscale oxygen carrier development. Mechanistic insights in the redox reactions of the oxygen carriers and their implications for the design and optimization of oxygen carriers for chemical looping combustion and partial oxidation reactions are also discussed.}, journal={CURRENT OPINION IN CHEMICAL ENGINEERING}, author={Mishra, Amit and Li, Fanxing}, year={2018}, month={Jun}, pages={143–150} }
 @article{campbell_parker_bennett_yusuf_al-rashdi_lustik_li_abolhasani_2018, title={Continuous Synthesis of Monodisperse Yolk-Shell Titania Microspheres}, volume={30}, ISSN={["1520-5002"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85058547405&partnerID=MN8TOARS}, DOI={10.1021/acs.chemmater.8b04349}, abstractNote={A microfluidic strategy is developed for continuous synthesis of monodisperse yolk–shell titania microspheres. The continuous flow synthesis of titania microparticles is achieved by decoupling the microdroplet formation and interfacial hydrolysis reaction steps by utilizing a polar aprotic solvent as the continuous phase in the microreactor. The decoupling of the precursor microdroplet formation and the hydrolysis reaction allows titania synthesis throughputs an order of magnitude higher than those previously reported in a single-channel flow reactor (∼0.1 g/h calcined microparticles), without affecting the microreactor lifetime due to clogging. Flow synthesis and dynamics across a broad range of precursor flow rates are examined, while effects of flow synthesis parameters, including the precursor to continuous phase flow rate ratio, precursor composition, and calcination temperature on the surface morphology, size, and composition of the resulting titania microparticles, are explored in detail. Titania m...}, number={24}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Campbell, Zachary S. and Parker, Matthew and Bennett, Jeffrey A. and Yusuf, Seif and Al-Rashdi, Amur K. and Lustik, Jacob and Li, Fanxing and Abolhasani, Milad}, year={2018}, month={Dec}, pages={8948–8958} }
 @article{haribal_chen_neal_li_2018, title={Intensification of Ethylene Production from Naphtha via a Redox Oxy-Cracking Scheme: Process Simulations and Analysis}, volume={4}, ISSN={["2096-0026"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053184335&partnerID=MN8TOARS}, DOI={10.1016/j.eng.2018.08.001}, abstractNote={Ethylene production by the thermal cracking of naphtha is an energy-intensive process (up to 40 GJ heat per tonne ethylene), leading to significant formation of coke and nitrogen oxide (NOx), along with 1.8–2 kg of carbon dioxide (CO2) emission per kilogram of ethylene produced. We propose an alternative process for the redox oxy-cracking (ROC) of naphtha. In this two-step process, hydrogen (H2) from naphtha cracking is selectively combusted by a redox catalyst with its lattice oxygen first. The redox catalyst is subsequently re-oxidized by air and releases heat, which is used to satisfy the heat requirement for the cracking reactions. This intensified process reduces parasitic energy consumption and CO2 and NOx emissions. Moreover, the formation of ethylene and propylene can be enhanced due to the selective combustion of H2. In this study, the ROC process is simulated with ASPEN Plus® based on experimental data from recently developed redox catalysts. Compared with traditional naphtha cracking, the ROC process can provide up to 52% reduction in energy consumption and CO2 emissions. The upstream section of the process consumes approximately 67% less energy while producing 28% more ethylene and propylene for every kilogram of naphtha feedstock.}, number={5}, journal={ENGINEERING}, author={Haribal, Vasudev Pralhad and Chen, Yun and Neal, Luke and Li, Fanxing}, year={2018}, month={Oct}, pages={714–721} }
 @article{yusuf_neal_haribal_baldwin_lamb_li_2018, title={Manganese silicate based redox catalysts for greener ethylene production via chemical looping - oxidative dehydrogenation of ethane}, volume={232}, ISSN={["1873-3883"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85044756308&partnerID=MN8TOARS}, DOI={10.1016/j.apcatb.2018.03.037}, abstractNote={The current study investigates manganese silicate based redox catalysts for ethane to ethylene conversion in a chemical looping oxidative dehydrogenation (CL-ODH) process. Facilitated by a two-step cyclic redox scheme, CL-ODH has the potential to overcome the drawbacks of traditional steam cracking including high energy consumption, coke formation, and significant CO2 and NOx emissions. In CL-ODH, lattice oxygen in manganese silicate based redox catalysts is used to combust the hydrogen formed from ethane dehydrogenation, enhancing ethylene formation and suppressing coke formation. The oxygen-deprived redox catalyst is subsequently regenerated with air, releasing heat to balance the overall heat requirement. The key to this process is an efficient redox catalyst with high selectivity and facile oxygen transport. In this study, redox catalysts with combined manganese and silica phases were tested. We report that redox catalysts with high manganese content are more effective for CL-ODH due to their higher oxygen capacity at reaction temperatures. Sodium tungstate was used as a promoter due to its effectiveness to suppress COx formation. Among the redox catalysts investigated, sodium tungstate promoted (1.7 wt.% Na) manganese silicate (Mn:Si molar ratio = 70:30) was the most effective, showing an ethylene selectivity of 82.6% and yield of 63.3%. Temperature programmed reaction (TPR) experiments indicate that the sodium tungstate promoter inhibits ethane activation on the surface of the redox catalyst and is selective towards hydrogen combustion. XPS analysis indicates that the manganese silicate redox catalysts have a smaller amount of near surface Mn4+ than previously studied manganese containing redox catalysts, leading to higher ethylene selectivity on the un-promoted redox catalysts. XPS also indicates that the reduction of the un-promoted redox catalysts leads to the consumption of silica and formation of inosilicate species. ASPEN Plus® simulations of the CL-ODH scheme using manganese silicate based redox catalysts indicate significant energy and emissions savings compared to traditional steam cracking: the overall energy consumption for ethylene production can potentially be reduced by 89% using the manganese silicate based redox catalyst in the CL-ODH process. Resulting from the significant energy savings, CO2/NOx emissions can be reduced by nearly one order of magnitude when compared to traditional steam cracking.}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, author={Yusuf, Seif and Neal, Luke and Haribal, Vasudev and Baldwin, Madison and Lamb, H. Henry and Li, Fanxing}, year={2018}, month={Sep}, pages={77–85} }
 @article{dudek_gao_zhang_li_2018, title={Manganese-containing redox catalysts for selective hydrogen combustion under a cyclic redox scheme}, volume={64}, ISSN={0001-1541}, url={http://dx.doi.org/10.1002/AIC.16173}, DOI={10.1002/AIC.16173}, abstractNote={Selective hydrogen combustion (SHC) in the presence of light hydrocarbons was demonstrated with a series of Mncontaining mixed oxide redox catalysts in the context of a chemical looping-oxidative dehydrogenation scheme. Unpromoted and 20 wt % Na2WO4-promoted Mg6MnO8, SrMnO3, and CaMnO3 exhibited varying SHC capabilities at temperatures between 550 and 8508C. Reduction temperature of unpromoted redox catalysts increased in the order Mg6MnO8< SrMnO3<CaMnO3. Promotion with 20 wt % Na2WO4 resulted in more selective redox catalysts capable of high-temperature SHC. XPS analysis revealed a correlation between suppression of near-surface Mn and SHC selectivity. Na2WO4/CaMnO3 showed steady SHC performance (89% H2 conversion, 88% selectivity) at 8508C over 50 redox cycles. In series with a Cr2O3/Al2O3 ethane dehydrogenation catalyst, Na2WO4/CaMnO3 combusted 84% of H2 produced while limiting COx yield below 2%. The redox catalysts reported can be suitable for SHC in a cyclic redox scheme for the production of light olefins from alkanes. VC 2018 American Institute of Chemical Engineers AIChE J, 00: 000–000, 2018}, number={8}, journal={AIChE Journal}, publisher={Wiley}, author={Dudek, Ryan B. and Gao, Yunfei and Zhang, Junshe and Li, Fanxing}, year={2018}, month={Apr}, pages={3141–3150} }
 @book{li_zhu_gao_2018, title={Materials and Methods for Oxidative Dehydrogenation of Alkyl Aromatic Compounds Involving Lattice Oxygen of Transition Metal Oxides}, number={US10946365B2}, author={Li, Fanxing and Zhu, Xing and Gao, Yunfei}, year={2018} }
 @misc{li_galinsky_shafiefarhood_2018, title={Mixed Metal Oxide-Based Oxygen Carriers for Chemical Looping Applications}, url={http://dx.doi.org/10.1002/9783527809332.ch8}, DOI={10.1002/9783527809332.ch8}, abstractNote={This chapter discusses the importance of bulk and surface properties for oxygen carrier design in selective oxidation applications. Chemical looping with oxygen uncoupling (CLOU) differs from traditional chemical-looping combustion (CLC) primarily in terms of the way oxygen is delivered from the oxygen carrier to the fuel. Chemical looping scheme offers quite a few advantages over methane combustion and reforming by preventing direct contact between the fuel and gaseous oxygen. Chemical looping processes rely on the redox properties of transition metal oxides for the oxidation of carbon-containing fuels. With emerging applications for chemical looping-based processes, the need for rational design of mixed oxide-based redox catalysts for different purposes is felt more than ever. Deeper understanding of the surface reaction mechanisms and bulk properties of different phases are crucial for a truly rational material selection.}, journal={Handbook of Chemical Looping Technology}, publisher={Wiley-VCH Verlag GmbH & Co. KGaA}, author={Li, Fanxing and Galinsky, Nathan and Shafiefarhood, Arya}, year={2018}, month={Oct}, pages={229–261} }
 @article{novotny_yusuf_li_lamb_2018, title={Oxidative dehydrogenation of ethane using MoO3/Fe2O3 catalysts in a cyclic redox mode}, volume={317}, ISSN={["1873-4308"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042634041&partnerID=MN8TOARS}, DOI={10.1016/j.cattod.2018.02.046}, abstractNote={Oxidative dehydrogenation (ODH) of ethane offers large reductions in energy consumption and associated greenhouse gas emissions when compared to conventional steam cracking for ethylene production; however, catalytic ODH of ethane using co-fed O2 requires expensive air separation. As an alternative, we are investigating novel core-shell catalysts that utilize lattice oxygen (O2−) as the sole oxidant and operate in a cyclic redox mode. In this work, redox catalysts having 1, 3 and 6 monolayer (ML) equivalents of MoO3 on α-Fe2O3 and a stoichiometric ferric molybdate, Fe2(MoO4)3, were prepared, characterized by powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS), and temperature-programmed reduction (TPR) and evaluated for ethane ODH in a cyclic redox mode at 600 °C. The characterization data are consistent with a core-shell structure for the calcined MoO3/Fe2O3 catalysts with a mixed Mo-Fe oxide surface layer. H2 and ethane TPR evidence that the shell inhibits Fe2O3 reduction and decreases the ethane combustion activity of the fully oxidized catalyst. Covering the Fe2O3 core with MoO3 also increases ODH activity and ethylene selectivity. In cyclic redox mode at 600 °C, ethylene selectivity was 57–62% for catalysts with 3 and 6 ML equivalents of MoO3.}, journal={CATALYSIS TODAY}, author={Novotny, Petr and Yusuf, Seif and Li, Fanxing and Lamb, H. Henry}, year={2018}, month={Nov}, pages={50–55} }
 @article{dou_krzystowczyk_mishra_liu_li_2018, title={Perovskite Promoted Mixed Cobalt-Iron Oxides for Enhanced Chemical Looping Air Separation}, volume={6}, ISSN={["2168-0485"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85055169872&partnerID=MN8TOARS}, DOI={10.1021/acssuschemeng.8b03970}, abstractNote={Chemical looping air separation (CLAS) is a promising approach to produce high purity oxygen from air. Redox kinetics and oxygen carrying capacity of oxide-based oxygen carrier materials play a critical role in the overall performance of CLAS. In view of the fast lattice oxygen transport property of mixed-conductive perovskite materials, composites of La0.8Sr0.2CoxFe1–xO3 (LSCF) perovskite and mixed Co–Fe oxides (CF) were investigated for chemical looping air separation. The effects of Fe and perovskite addition were systematically examined by varying Co/Fe and LSCF/CF ratios. Increase of Fe in mixed Co–Fe oxides significantly increases oxidation kinetics of LSCF-CF composites while decreasing the rate of oxygen release. An optimized average redox rate was achieved by balancing the oxygen uptake (oxidation) and release (reduction) rates through tuning Co/Fe ratio, with the maximum occurring at a ratio of 9:1. Unpromoted Co–Fe mixed oxide exhibited a working oxygen capacity of 1.6 wt % at 850 °C. With the ...}, number={11}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Dou, Jian and Krzystowczyk, Emily and Mishra, Amit and Liu, Xingbo and Li, Fanxing}, year={2018}, month={Nov}, pages={15528–15540} }
 @article{zhu_li_neal_li_2018, title={Perovskites as Geo-inspired Oxygen Storage Materials for Chemical Looping and Three-Way Catalysis: A Perspective}, volume={8}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85050819577&partnerID=MN8TOARS}, DOI={10.1021/acscatal.8b01973}, abstractNote={With highly tunable composition, structure, and chemical-physical properties, perovskite oxides represent a large family of mixed-oxide materials that finds many energy- and environment-related applications. This perspective discusses the fundamentals and applications of perovskite oxides in the context of chemical looping and three-way catalysis (TWC). Both applications make use of perovskite oxides’ oxygen storage and donation properties (>400 μmol O/g) under macroscopic reduction–oxidation (redox) cycles and at elevated temperatures. While perovskite oxides have been investigated as oxygen storage materials (OSMs) and three-way catalysts for more than five decades, use of these oxides in chemical looping, as oxygen carriers or redox catalysts, is a relatively new topic. This article provides an account of the effects of compositional, structural, and surface properties of perovskites on their oxygen storage and donation properties as well as their interactions with various gaseous reactants. Design and...}, number={9}, journal={ACS CATALYSIS}, author={Zhu, Xing and Li, Kongzhai and Neal, Luke and Li, Fanxing}, year={2018}, month={Sep}, pages={8213–8236} }
 @article{haribal_he_mishra_li_2017, title={Cover Feature: Iron-Doped BaMnO3
 for Hybrid Water Splitting and Syngas Generation (ChemSusChem 17/2017)}, volume={10}, ISSN={1864-5631}, url={http://dx.doi.org/10.1002/CSSC.201701620}, DOI={10.1002/CSSC.201701620}, abstractNote={The Back Cover picture shows the exceptional syngas yield and water-splitting conversion obtained using iron-doped BaMnO3 redox catalyst in a hybrid solar-redox scheme. Density functional theory and thermodynamic calculations predict that BaMn0.5Fe0.5O3−δ be suitable for the reaction scheme. Experimental studies demonstrated 90% steam-to-hydrogen conversion during water splitting and over 90% syngas yield in the methane partial-oxidation step. The redox catalyst can be used to efficiently produce liquid fuel and hydrogen. More details can be found in the Full Paper by Haribal et al. on page 3402 in Issue 17, 2017 (DOI: 10.1002/cssc.201700699).}, number={17}, journal={ChemSusChem}, publisher={Wiley}, author={Haribal, Vasudev Pralhad and He, Feng and Mishra, Amit and Li, Fanxing}, year={2017}, month={Sep}, pages={3282–3282} }
 @article{yusuf_neal_li_2017, title={Effect of Promoters on Manganese-Containing Mixed Metal Oxides for Oxidative Dehydrogenation of Ethane via a Cyclic Redox Scheme}, volume={7}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85027258022&partnerID=MN8TOARS}, DOI={10.1021/acscatal.7b02004}, abstractNote={Ethylene is an important building block in the chemical industry; state of the art ethylene production (steam cracking) has multiple drawbacks, including high energy consumption, coke formation, and significant CO2 and NOx emissions. We propose a chemical looping oxidative dehydrogenation (CL-ODH) process to convert ethane into ethylene in a two-step, cyclic redox scheme. In this process, lattice oxygen in a metal oxide based redox catalyst is used to combust the hydrogen formed in ethane dehydrogenation, thereby enhancing ethylene formation while retarding coke formation. The oxygen-deprived redox catalyst is subsequently regenerated with air, releasing heat to balance the overall heat requirement. CL-ODH can realize a reduction of over 80% in primary energy consumption and pollutant emissions. The key to this process is an efficient redox catalyst with high selectivity and facile oxygen transport. Previously we determined that oxides with an Mg6MnO8 structure allow high lattice oxygen mobility and satis...}, number={8}, journal={ACS CATALYSIS}, author={Yusuf, Seif and Neal, Luke M. and Li, Fanxing}, year={2017}, month={Aug}, pages={5163–5173} }
 @article{haribal_he_mishra_li_2017, title={Iron-Doped BaMnO3 for Hybrid Water Splitting and Syngas Generation}, volume={10}, ISSN={["1864-564X"]}, url={https://doi.org/10.1002/cssc.201700699}, DOI={10.1002/cssc.201700699}, abstractNote={Abstract}, number={17}, journal={CHEMSUSCHEM}, publisher={Wiley}, author={Haribal, Vasudev Pralhad and He, Feng and Mishra, Amit and Li, Fanxing}, year={2017}, month={Sep}, pages={3402–3408} }
 @article{haribal_neal_li_2017, title={Oxidative dehydrogenation of ethane under a cyclic redox scheme - Process simulations and analysis}, volume={119}, ISSN={["1873-6785"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85007442920&partnerID=MN8TOARS}, DOI={10.1016/j.energy.2016.11.039}, abstractNote={Steam cracking of ethane is an energy intensive process (15–25 GJth/tonne ethylene) involving significant coke formation and CO2/NOx emissions. We propose an alternative two-step redox (or chemical looping) oxidative dehydrogenation (CL-ODH) scheme where hydrogen, produced from ethane cracking, is selectively oxidized by lattice oxygen from a redox catalyst, in the first step. Regeneration of the lattice oxygen in a subsequent step heats the redox catalyst, with the sensible heat providing the thermal energy needed for the cracking reaction. The overall process provides minimal parasitic energy loss and significantly reduced CO2/NOx formation, while favoring ethylene formation through the removal of hydrogen. In the current study, the CL-ODH process is simulated with ASPEN Plus® using experimental data on a Mn-based redox catalyst. The CL-ODH is compared with steam cracking for an ethylene production capacity of 1 million tonne/year. Results indicate that the CL-ODH process, with 85% single-pass ethane conversion, provides 82% reduction in overall energy demand and 82% reduction in CO2 emissions. The overall downstream section consumes approximately 23.5% less energy, with 32.1% less compression work. Increase in the ethane conversion further reduces the energy demand downstream. For every tonne of ethylene, the process has 7.35 GJth excess fuel energy whereas cracking requires an external fuel input of 1.42 GJth.}, journal={ENERGY}, author={Haribal, Vasudev Pralhad and Neal, Luke M. and Li, Fanxing}, year={2017}, month={Jan}, pages={1024–1035} }
 @article{he_linak_deng_li_2017, title={Particulate Formation from a Copper Oxide-Based Oxygen Carrier in Chemical Looping Combustion for CO2 Capture}, volume={51}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85014649777&partnerID=MN8TOARS}, DOI={10.1021/acs.est.6b04043}, abstractNote={Attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane chemical looping combustion (CLC) process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling duct, range between 2 and 5 μm. A notable number of submicrometer particulates are also identified. Oxygen carrier attrition was observed to lead to increased CuO loss resulting from the chemical looping reactions, i.e., Cu is enriched in small particles generated primarily from fragmentation in the size range of 10-75 μm. Cyclic reduction and oxidation reactions in CLC have been determined to weaken the oxygen carrier particles, resulting in increased particulate emission rates when compared to those of oxygen carriers without redox reactions. The generation rate for particulates <10 μm was found to decrease with progressive cycles over as-prepared oxygen carrier particles and then reach a steady state. The surface of the oxygen carrier is also found to be coarsened due to a Kirkendall effect, which also explains the enrichment of Cu on particle surfaces and in small particles.}, number={4}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={He, Feng and Linak, William P. and Deng, Shuang and Li, Fanxing}, year={2017}, month={Feb}, pages={2482–2490} }
 @article{zhang_haribal_li_2017, title={Perovskite nanocomposites as effective CO2-splitting agents in a cyclic redox scheme}, volume={3}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.1701184}, DOI={10.1126/sciadv.1701184}, abstractNote={
            A methane-to-syngas selectivity of 96% and a CO yield of nearly 100% in CO
            2
            splitting were achieved over perovskite nanocomposites in a cyclic redox scheme.
          }, number={8}, journal={SCIENCE ADVANCES}, publisher={American Association for the Advancement of Science (AAAS)}, author={Zhang, Junshe and Haribal, Vasudev and Li, Fanxing}, year={2017}, month={Aug} }
 @article{shafiefarhood_zhang_neal_li_2017, title={Rh-promoted mixed oxides for "low-temperature" methane partial oxidation in the absence of gaseous oxidants}, volume={5}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/C7TA01398A}, DOI={10.1039/c7ta01398a}, abstractNote={Rh promoted mixed-oxides show a syngas productivity of 7.9 mmol g−1 at 600 °C in the absence of gaseous oxidants.}, number={23}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Shafiefarhood, Arya and Zhang, Junshe and Neal, Luke Michael and Li, Fanxing}, year={2017}, month={Jun}, pages={11930–11939} }
 @article{galinsky_sendi_bowers_li_2016, title={CaMn1-xBxO3-delta (B = Al, V, Fe, Co, and Ni) perovskite based oxygen carriers for chemical looping with oxygen uncoupling (CLOU)}, volume={174}, ISSN={["1872-9118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84963788767&partnerID=MN8TOARS}, DOI={10.1016/j.apenergy.2016.04.046}, abstractNote={Operated under a cyclic redox mode in the presence of an oxygen carrier, the chemical looping with oxygen uncoupling (CLOU) process has the potential to effectively combust solid carbonaceous fuels while capturing CO2. The overall process is enabled by an oxygen carrier that is capable of reversibly exchanging its lattice oxygen (O2−) with gaseous oxygen (O2) under varying external oxygen partial pressures (PO2). As such, further improvements of the CLOU process relies largely on the identification of oxygen carriers with higher activity, better recyclability, and improved resistance toward physical degradation. This article investigates dopant effects on CLOU properties of oxygen carriers with a CaMnO3 parent structure. Various B-site compatible metal cations including Fe, Ni, Co, V, and Al are incorporated into the perovskite. While CaMnO3 suffers from stability issues resulting from irreversible transitions to spinel (CaMn2O4) and Ruddlesden–Popper (Ca2MnO4) structures under typical CLOU redox conditions, a number of B-site doped perovskites exhibited promising phase stability and redox activity. Of the oxygen carriers investigated, Fe-doped CaMnO3 exhibits the most promising CLOU properties while showing high compatibility with the CaMnO3 parent structure. In terms of redox performance, CaMn1−xFexO3−δ exhibit notable redox activity at temperatures as low as 600 °C. No deactivation was observed over 100 redox cycles. The doped perovskite structure was also significantly more stable than undoped CaMnO3, showing no signs of decomposition at 1200 °C. When operated under identical conditions, the Fe-doped oxygen carrier is observed to achieve significantly higher conversion of Pittsburgh #8 coal char compared to undoped CaMnO3 oxygen carrier, when operated at 850 °C.}, journal={APPLIED ENERGY}, author={Galinsky, Nathan and Sendi, Marwan and Bowers, Lindsay and Li, Fanxing}, year={2016}, month={Jul}, pages={80–87} }
 @inproceedings{prabakar_li_xiao_2016, title={Controller hardware-in-loop testbed setup for multi-objective optimization based tuning of inverter controller parameters in a microgrid setting}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973922649&partnerID=MN8TOARS}, DOI={10.1109/PSC.2016.7462824}, abstractNote={A multi-objective optimization based inverter controller parameter tuning for a microgrid setup is proposed here. In order to facilitate easy transfer from tuned controller to actual inverter hardware, a real time digital simulator and FPGA based controller hardware-in-loop setup is employed for the tuning. Inverters used under such microgrid setup need to operate in different modes. This is due to the microgrids' need to connect and disconnect from the grid. Control setup used in both modes of operation will be tuned using the proposed controller hardware-in-loop setup and the optimization method. The results indicate that optimization based tuning can generate optimal gain values regardless of the mode of operation of the inverter.}, booktitle={Clemson University Power Systems Conference, PSC 2016}, author={Prabakar, K. and Li, F. and Xiao, B.}, year={2016} }
 @book{li_neal_2016, title={Improved Ethylene Yield via Byproduct Recycles in Oxidative Dehydrogenation of Ethane and Ethane Containing Hydrocarbon Mixtures}, number={US10550051B2}, author={Li, Fanxing and Neal, Luke}, year={2016} }
 @article{neal_yusuf_sofranko_li_2016, title={Inside Cover: Oxidative Dehydrogenation of Ethane: A Chemical Looping Approach (Energy Technol. 10/2016)}, volume={4}, ISSN={2194-4288}, url={http://dx.doi.org/10.1002/ENTE.201600464}, DOI={10.1002/ENTE.201600464}, abstractNote={Throwing ethane for a chemical loop: The cover art illustration presents a chemical looping (CL)–oxidative dehydrogenation (ODH) scheme for ethylene production from ethane. CL–ODH uses promoted Mg6MnO8 as the oxygen carrier (i.e., redox catalyst). In the ODH reactor, the promoted Mg6MnO8 is reduced while converting ethane to ethylene and water. The reduced redox catalyst is then transferred to the regenerator where it is re-oxidized with air before circulating back to the ODH reactor to complete the chemical loop. Heat from the regenerator is also transferred to the ODH reactor along with the redox catalyst particles. The CL–ODH scheme is shown to be able to achieve significantly higher ethane conversion and ethylene yield than thermal cracking while reducing the energy consumption and CO2/NOx emissions. You can read more in the Full Paper by Luke Neal, Seif Yusuf, John Sofranko, and Fanxing Li from North Carolina State University on page 1200 in Issue 10, 2016 (DOI: 10.1002/ente.201600074).}, number={10}, journal={Energy Technology}, publisher={Wiley}, author={Neal, Luke M. and Yusuf, Seif and Sofranko, John A. and Li, Fanxing}, year={2016}, month={Oct}, pages={1126–1126} }
 @article{gao_neal_li_2016, title={Li-Promoted LaxSr2-xFeO4-delta Core-Shell Redox Catalysts for Oxidative Dehydrogenation of Ethane under a Cyclic Redox Scheme}, volume={6}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84994627994&partnerID=MN8TOARS}, DOI={10.1021/acscatal.6b01399}, abstractNote={Chemical looping oxidative dehydrogenation (CL-ODH) of ethane utilizes a transition metal oxide based oxygen carrier, also known as a redox catalyst, to convert ethane into ethylene under an autothermal cyclic redox scheme. The current study investigates a Li-promoted LaxSr2–xFeO4−δ (LaSrFe) redox catalyst for CL-ODH reactions. While LaSrFe without Li promoter exhibits low ethylene selectivity, addition of Li leads to high selectivity/yield and good regenerability. Up to 61% ethane conversion and 90% ethylene selectivity are achieved with Li-promoted LaSrFe. Further characterization indicates that the Li-promoted LaSrFe redox catalyst consists of LiFeO2 (disordered rock salt) and LaSrFe (Ruddlesden–Popper) phases. Moreover, the surface of the redox catalysts is enriched with Li cations. It is also determined the LaSrFe phase contributes to oxygen storage and donation, whereas the activity and selectivity of the redox catalysts are modified by the Li promoter: while oxygen for the CL-ODH reaction is suppli...}, number={11}, journal={ACS CATALYSIS}, author={Gao, Yunfei and Neal, Luke M. and Li, Fanxing}, year={2016}, month={Nov}, pages={7293–7302} }
 @article{mundy_shafiefarhood_li_khan_parsons_2016, title={Low temperature platinum atomic layer deposition on nylon-6 for highly conductive and catalytic fiber mats}, volume={34}, ISSN={["1520-8559"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84953317899&partnerID=MN8TOARS}, DOI={10.1116/1.4935448}, abstractNote={Low temperature platinum atomic layer deposition (Pt-ALD) via (methylcyclopentadienyl)trimethyl platinum and ozone (O3) is used to produce highly conductive nonwoven nylon-6 (polyamide-6, PA-6) fiber mats, having effective conductivities as high as ∼5500–6000 S/cm with only a 6% fractional increase in mass. The authors show that an alumina ALD nucleation layer deposited at high temperature is required to promote Pt film nucleation and growth on the polymeric substrate. Fractional mass gain scales linearly with Pt-ALD cycle number while effective conductivity exhibits a nonlinear trend with cycle number, corresponding to film coalescence. Field-emission scanning electron microscopy reveals island growth mode of the Pt film at low cycle number with a coalesced film observed after 200 cycles. The metallic coating also exhibits exceptional resistance to mechanical flexing, maintaining up to 93% of unstressed conductivity after bending around cylinders with radii as small as 0.3 cm. Catalytic activity of the as-deposited Pt film is demonstrated via carbon monoxide oxidation to carbon dioxide. This novel low temperature processing allows for the inclusion of highly conductive catalytic material on a number of temperature-sensitive substrates with minimal mass gain for use in such areas as smart textiles and flexible electronics.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Mundy, J. Zachary and Shafiefarhood, Arya and Li, Fanxing and Khan, Saad A. and Parsons, Gregory N.}, year={2016}, month={Jan} }
 @article{neal_yusuf_sofranko_li_2016, title={Oxidative Dehydrogenation of Ethane: A Chemical Looping Approach}, volume={4}, ISSN={2194-4288}, url={http://dx.doi.org/10.1002/ENTE.201600074}, DOI={10.1002/ENTE.201600074}, abstractNote={Abstract}, number={10}, journal={Energy Technology}, publisher={Wiley}, author={Neal, Luke M. and Yusuf, Seif and Sofranko, John A. and Li, Fanxing}, year={2016}, month={Jun}, pages={1200–1208} }
 @article{mishra_galinsky_he_santiso_li_2016, title={Perovskite-structured AMn(x)B(1-x)O(3) (A = Ca or Ba; B = Fe or Ni) redox catalysts for partial oxidation of methane}, volume={6}, ISSN={["2044-4761"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84975156629&partnerID=MN8TOARS}, DOI={10.1039/c5cy02186c}, abstractNote={High oxygen carrying capacity, lack of loosely bound lattice oxygen, and preferential surface segregation of Ba make BaMnxB1−xO3 (B = Ni or Fe) based redox catalysts suitable for chemical looping reforming of methane with high syngas yield and coke resistance.}, number={12}, journal={CATALYSIS SCIENCE & TECHNOLOGY}, author={Mishra, Amit and Galinsky, Nathan and He, Feng and Santiso, Erik E. and Li, Fanxing}, year={2016}, pages={4535–4544} }
 @inproceedings{tian_yan_yang_li_hu_2016, title={Positioning control system of three-dimensional wafer stage of lithography}, volume={9685}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84999752032&partnerID=MN8TOARS}, DOI={10.1117/12.2244874}, abstractNote={Three-dimensional wafer stage is an important component of lithography. It is required to high positioning precision and efficiency. The closed-loop positioning control system, that consists of five-phase step motor and grating scale, implements rapid and precision positioning control of the three-dimensional wafer stage. The MCU STC15W4K32S4, which is possession of six independent PWM output channels and the pulse width, period is adjustable, is used to control the three axes. The stepper motor driver and grating scale are subdivided according to the precision of lithography, and grating scale data is transmitted to the computer for display in real time via USB communication. According to the lithography material, mask parameter, incident light intensity, it's able to calculate the speed of Z axis, and then get the value of PWM period based on the mathematical formula of speed and pulse period, finally realize high precision control. Experiments show that the positioning control system of three-dimensional wafer stage can meet the requirement of lithography, the closed-loop system is high stability and precision, strong practicability.}, booktitle={Proceedings of SPIE - The International Society for Optical Engineering}, author={Tian, P. and Yan, W. and Yang, F. and Li, F. and Hu, S.}, year={2016} }
 @article{galinsky_mishra_zhang_li_2015, title={Ca(1-x)A(x)MnO(3) (A = Sr and Ba) perovskite based oxygen carriers for chemical looping with oxygen uncoupling (CLOU)}, volume={157}, ISSN={["1872-9118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85007035468&partnerID=MN8TOARS}, DOI={10.1016/j.apenergy.2015.04.020}, abstractNote={Operated under a cyclic redox mode with an oxygen carrier, the chemical looping with oxygen uncoupling (CLOU) process offers the potential to effectively combust solid fuels while capturing CO2. Development of oxygen carriers capable of reversibly exchanging their active lattice oxygen (O2−) with gaseous oxygen (O2) under varying external oxygen partial pressure (PO2) is of key importance to CLOU process performance. This article investigates the effect of A-site dopants on CaMnO3 based oxygen carriers for CLOU. Both Sr and Ba are explored as potential dopants at various concentrations. Phase segregations are observed with the addition of Ba dopant even at relatively low concentrations (5% A-site doping). In contrast, stable solid solutions are formed with Sr dopant at a wide range of doping level. While CaMnO3 perovskite suffers from irreversible change into Ruddlesden–Popper (Ca2MnO4) and spinel (CaMn2O4) phases under cyclic redox conditions, Sr doping is found to effectively stabilize the perovskite structure. In-situ XRD studies indicate that the Sr doped CaMnO3 maintains a stable orthorhombic perovskite structure under an inert environment (tested up to 1200 °C). The same oxygen carrier sample exhibited high recyclability over 100 redox cycles at 850 °C. Besides being highly recyclable, Sr doped CaMnO3 is found to be capable of releasing its lattice oxygen at a temperature significantly lower than that for CaMnO3, rendering it a potentially effective oxygen carrier for solid fuel combustion and carbon dioxide capture.}, journal={APPLIED ENERGY}, author={Galinsky, Nathan and Mishra, Amit and Zhang, Jia and Li, Fanxing}, year={2015}, month={Nov}, pages={358–367} }
 @article{zhang_li_2015, title={Coke-resistant Ni@SiO2 catalyst for dry reforming of methane}, volume={176}, ISSN={["1873-3883"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84928253240&partnerID=MN8TOARS}, DOI={10.1016/j.apcatb.2015.04.039}, abstractNote={Nanostructured Ni@SiO2 core–shell catalyst is prepared from nickel oxide nanoparticles by a facile method. Calcination of as-synthesized core–shell nanoparticles creates a micro/meso-porous structure in the amorphous silica shell. The catalytic performance of core–shell catalyst toward dry reforming of methane was first evaluated in a thermogravimeter coupled with a mass spectrometer. Coking is negligible in a reforming period of 40 h on stream at 850 °C, while more than 0.32 gcoke gcat−1 is produced on a commercial Ni-based reforming catalyst in 6.4 h at the same reforming condition. Dry reforming was also performed in a continuous flow, fixed-bed reactor at 750 °C. Characterization of spent catalyst further confirms that Ni@SiO2 catalyst has high coke-resistance for dry reforming. The amount of coke deposited on the core–shell catalyst in 24.5 h is 0.012 gcoke gcat−1.}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, author={Zhang, Junshe and Li, Fanxing}, year={2015}, month={Oct}, pages={513–521} }
 @article{neal_shafiefarhood_li_2015, title={Effect of core and shell compositions on MeOx@LaySr1-yFeO3 core-shell redox catalysts for chemical looping reforming of methane}, volume={157}, ISSN={["1872-9118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84945124544&partnerID=MN8TOARS}, DOI={10.1016/j.apenergy.2015.06.028}, abstractNote={The chemical looping reforming (CLR) process converts methane into syngas through cyclic redox reactions of an active lattice oxygen (O2−) containing redox catalyst. In CLR, methane is partially oxidized to CO and H2 using the active lattice oxygen of a redox catalyst. In a subsequent step, the oxygen-deprived redox catalyst is regenerated by air. Such a process can eliminate the need for steam and/or oxygen in reforming, thereby improving methane conversion efficiency. A number of perovskite-structured mixed metal oxides are known to be active for CLR. However, the oxygen storage capacity of perovskites tends to be low, limiting their practical application in chemical looping. In contrast reducible metal oxides such as cobalt and iron oxides can store up to 30 wt.% lattice oxygen but are less selective for syngas generation. We explore oxygen carriers that utilize the advantages of both perovskites and first-row transition metal oxides by integrating a transition metal oxide core with a mixed ionic–electronic conductive (MIEC) perovskite support/shell. MIEC perovskites facilitate countercurrent conduction of O2− and electrons, allowing facile O2− transport though the solid. It is proposed that this conduction allows rapid oxygen transport to and from the transition metal oxide cores irrespective of the porosity of the redox catalyst. In this work, we show that MeOx@LaySr1−yFeO3 can be an excellent model catalyst system for CLR. The activity, selectivity, and coke resistance of the core–shell system can be tuned by changing the ratio of La to Sr in the perovskite shell and the type of transition metal oxide in the core. Our studies indicate that lower Sr loadings can improve activity and selectivity of the catalyst for methane partial oxidation, but make the LSF shell less resistant to decomposition during the reduction step.}, journal={APPLIED ENERGY}, author={Neal, Luke and Shafiefarhood, Arya and Li, Fanxing}, year={2015}, month={Nov}, pages={391–398} }
 @article{galinsky_shafiefarhood_chen_neal_li_2015, title={Effect of support on redox stability of iron oxide for chemical looping conversion of methane}, volume={164}, ISSN={["1873-3883"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84908004028&partnerID=MN8TOARS}, DOI={10.1016/j.apcatb.2014.09.023}, abstractNote={The chemical looping processes utilize lattice oxygen in oxygen carriers to convert carbonaceous fuels in a cyclic redox mode while capturing CO2. Typical oxygen carriers are composed of a primary oxide for active lattice oxygen storage and a ceramic support for enhanced redox stability and activity. Among the various primary oxides reported to date, iron oxide represents a promising option due to its low cost and natural abundance. The current work investigates the effect of support on the cyclic redox performance of iron oxides as well as the underlying mechanisms. Three ceramic supports with varying physical and chemical properties, i.e. perovskite-structured Ca0.8Sr0.2Ti0.8Ni0.2O3, fluorite-structured CeO2, and spinel-structured MgAl2O4, are investigated. The results indicate that the redox properties of the oxygen carrier, e.g. activity and long-term stability, are significantly affected by support and iron oxide interactions. The perovskite supported oxygen carrier exhibits high activity and stability compared to oxygen carriers with ceria support, which deactivate by as much as 75% within 10 redox cycles. The high stability of perovskite supported oxygen carrier is attributable to its high mixed ionic–electronic conductivity. Deactivation of ceria supported samples results from solid-state migration of iron cations and subsequent enrichment on the oxygen carrier surface. This leads to agglomeration and lowered lattice oxygen accessibility. Activity of MgAl2O4 supported oxygen carrier is found to increase during redox cycles in methane. The activity increase is a consequence of surface area increase caused by filamentous carbon formation and oxygen carrier fragmentation. While higher redox activity is desired for chemical looping processes, physical degradation of oxygen carriers can be detrimental.}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, author={Galinsky, Nathan L. and Shafiefarhood, Arya and Chen, Yanguang and Neal, Luke and Li, Fanxing}, year={2015}, month={Mar}, pages={371–379} }
 @article{shafiefarhood_stewart_li_2015, title={Iron-containing mixed-oxide composites as oxygen carriers for Chemical Looping with Oxygen Uncoupling (CLOU)}, volume={139}, ISSN={["1873-7153"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906877965&partnerID=MN8TOARS}, DOI={10.1016/j.fuel.2014.08.014}, abstractNote={Chemical Looping with Oxygen Uncoupling (CLOU) offers a potentially effective approach for converting solid carbonaceous fuels with inherent carbon dioxide capture. It utilizes oxygen carriers that allow facile and reversible exchange of their lattice oxygen with external environment under varying oxygen partial pressures. The varying and often tunable thermodynamic properties of mixed oxides of first row transition metals make them potentially viable for CLOU applications. In this study, mixed iron–cobalt and iron–manganese oxides are synthesized and evaluated in terms of their ability to uncouple oxygen. The effects of adding a secondary perovskite phase on the uncoupling properties of these primary transition metal oxides are also investigated. The experimental results indicate that different cation compositions exhibit different oxygen uncoupling properties. The initial decomposition temperature of the oxygen carrier sample is found to generally decrease with increasing amount of Co or Mn. Addition of a secondary perovskite phase is found to significantly affect oxygen donation properties of the primary mixed metal oxides. For instance, CLOU properties of mixed Fe–Co oxides are enhanced by perovskite addition. In contrast, oxygen carrying capacity of mixed Fe–Mn oxides under an isothermal condition is negatively affected by perovskite addition. Redistribution of the transition metal cations between the primary and secondary oxide phases is likely to be responsible for such changes in their redox properties.}, journal={FUEL}, author={Shafiefarhood, Arya and Stewart, Amy and Li, Fanxing}, year={2015}, month={Jan}, pages={1–10} }
 @article{shafiefarhood_hamill_neal_li_2015, title={Methane partial oxidation using FeOx@La0.8Sr0.2FeO3-delta core-shell catalyst - transient pulse studies}, volume={17}, ISSN={["1463-9084"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84947779267&partnerID=MN8TOARS}, DOI={10.1039/c5cp05583k}, abstractNote={Study on the mechanism of C–H bond activation and kinetic pathways of methane conversion using FeOx@La0.8Sr0.2FeO3 redox catalyst.}, number={46}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, author={Shafiefarhood, Arya and Hamill, Joseph Clay and Neal, Luke Michael and Li, Fanxing}, year={2015}, pages={31297–31307} }
 @article{he_li_2015, title={Perovskite promoted iron oxide for hybrid water-splitting and syngas generation with exceptional conversion}, volume={8}, ISSN={["1754-5706"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84929398168&partnerID=MN8TOARS}, DOI={10.1039/c4ee03431g}, abstractNote={Under a cyclic redox mode, a perovskite promoted iron oxide exhibited 77% steam-to-hydrogen conversion in a layered reverse-flow reactor.}, number={2}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={He, Feng and Li, Fanxing}, year={2015}, pages={535–539} }
 @inproceedings{sofranko_neal_li_2015, title={Reducing emissions from olefin production via chemical looping ODH technology}, volume={2015-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84948670528&partnerID=MN8TOARS}, booktitle={AIChE Ethylene Producers Conference Proceedings}, author={Sofranko, J.A. and Neal, L.M. and Li, F.}, year={2015}, pages={548–555} }
 @inproceedings{he_li_2014, title={A hybrid solar-redox process for hydrogen and liquid fuel Co-production - Redox material development and process analyses}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84954237336&partnerID=MN8TOARS}, booktitle={Catalysis and Reaction Engineering Division 2014 - Core Programming Area at the 2014 AIChE Annual Meeting}, author={He, F. and Li, F.}, year={2014} }
 @article{he_trainham_parsons_newman_li_2014, title={A hybrid solar-redox scheme for liquid fuel and hydrogen coproduction}, volume={7}, ISSN={["1754-5706"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84901297865&partnerID=MN8TOARS}, DOI={10.1039/c4ee00038b}, abstractNote={A ferrite based oxygen carrier promoted with a mixed ionic–electronic conductor support is used in a hybrid solar-redox scheme. Based on both experiments and simulations, this scheme has the potential to co-produce liquid fuel and hydrogen from methane and solar energy at high efficiency with near zero life cycle CO2 emission.}, number={6}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={He, Feng and Trainham, James and Parsons, Gregory N. and Newman, John S. and Li, Fanxing}, year={2014}, month={Jun}, pages={2033–2042} }
 @inproceedings{zhang_li_2014, title={Coke-resistant core-shell catalysts for dry reforming of methane}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84954326428&partnerID=MN8TOARS}, booktitle={Catalysis and Reaction Engineering Division 2014 - Core Programming Area at the 2014 AIChE Annual Meeting}, author={Zhang, J. and Li, F.}, year={2014} }
 @article{neal_shafiefarhood_li_2014, title={Dynamic Methane Partial Oxidation Using a Fe2O3@La0.8Sr0.2FeO3-delta Core-Shell Redox Catalyst in the Absence of Gaseous Oxygen}, volume={4}, ISSN={["2155-5435"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84907855041&partnerID=MN8TOARS}, DOI={10.1021/cs5008415}, abstractNote={Chemical looping reforming partially oxidizes methane into syngas through cyclic redox reactions of an active lattice-oxygen (O2–) containing redox catalyst. The avoidance of direct contact between methane and steam and/or gaseous oxygen has the potential to eliminate the energy consumption for generating these oxidants, thereby increasing methane conversion efficiency. This article investigates redox catalysts comprised of iron oxide core covered with lanthanum strontium ferrite (LSF) shell. The iron oxide core serves as the primary source of lattice-oxygen, whereas the LSF shell provides an active surface and facilitates O2– and electron conductions. These core–shell materials have the promise to provide higher selectivity for methane conversion with lower solid circulation rates than traditional redox catalysts. Methane oxidation by this catalyst exhibits four distinct regions, i.e. deep oxidation; competing deep and selective oxidation; selective oxidation with autoactivation; and methane decompositio...}, number={10}, journal={ACS CATALYSIS}, author={Neal, Luke M. and Shafiefarhood, Arya and Li, Fanxing}, year={2014}, month={Oct}, pages={3560–3569} }
 @article{liu_li_hu_wiltberger_ryll_2014, title={Effects of Bubble-Liquid Two-Phase Turbulent Hydrodynamics on Cell Damage in Sparged Bioreactor}, volume={30}, ISSN={["1520-6033"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84893793023&partnerID=MN8TOARS}, DOI={10.1002/btpr.1790}, abstractNote={According to recent experimental studies on sparged bioreactors, significant cell damage may occur at the gas inlet region near the sparger. Although shear stress was proposed to be one of the potential causes for cell damage, detailed hydrodynamic studies at the gas inlet region of gas–liquid bioreactors have not been performed to date. In this work, a second‐order moment (SOM) bubble–liquid two‐phase turbulent model based on the two‐fluid continuum approach is used to investigate the gas–liquid hydrodynamics in the bubble column reactor and their potential impacts on cell viability, especially at the gas inlet region. By establishing fluctuation velocity and bubble–liquid two‐phase fluctuation velocities correlation transport equations, the anisotropy of two‐phase stresses and the bubble–liquid interactions are fully considered. Simulation results from the SOM model indicate that shear and normal stresses, turbulent energy dissipation rate, and the turbulent kinetic energy are generally smaller at the gas inlet region when compared with those in the fully developed region. In comparison, a newly proposed correlation expression, stress‐induced turbulent energy production (STEP), is found to correlate well with the unusually high cell death rate at the gas inlet region. Therefore, STEP, which represents turbulent energy transfer to a controlled volume induced by a combination of shear and normal stresses, has the potential to provide better explanation for increased cell death at the sparger region. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:48–58, 2014}, number={1}, journal={BIOTECHNOLOGY PROGRESS}, author={Liu, Yang and Li, Fanxing and Hu, Weiwei and Wiltberger, Kelly and Ryll, Thomas}, year={2014}, month={Jan}, pages={48–58} }
 @inproceedings{he_li_2014, title={Experimental and simulation studies of a hybrid solar-redox scheme for liquid fuel and hydrogen coproduction}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84958623146&partnerID=MN8TOARS}, booktitle={Particle Technology Forum 2014 - Core Programming Area at the 2014 AIChE Annual Meeting}, author={He, F. and Li, F.}, year={2014}, pages={137–143} }
 @article{shafiefarhood_galinsky_huang_chen_li_2014, title={Fe2O3@LaxSr1-xFeO3 Core- Shell Redox Catalyst for Methane Partial Oxidation}, volume={6}, ISSN={["1867-3899"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84896870404&partnerID=MN8TOARS}, DOI={10.1002/cctc.201301104}, abstractNote={Abstract}, number={3}, journal={CHEMCATCHEM}, author={Shafiefarhood, Arya and Galinsky, Nathan and Huang, Yan and Chen, Yanguang and Li, Fanxing}, year={2014}, month={Mar}, pages={790–799} }
 @article{he_li_2014, title={Hydrogen production from methane and solar energy - Process evaluations and comparison studies}, volume={39}, ISSN={["1879-3487"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84914122341&partnerID=MN8TOARS}, DOI={10.1016/j.ijhydene.2014.05.089}, abstractNote={Three conventional and novel hydrogen and liquid fuel production schemes, i.e. steam methane reforming (SMR), solar SMR, and hybrid solar-redox processes are investigated in the current study. H2 (and liquid fuel) productivity, energy conversion efficiency, and associated CO2 emissions are evaluated based on a consistent set of process conditions and assumptions. The conventional SMR is estimated to be 68.7% efficient (HHV) with 90% CO2 capture. Integration of solar energy with methane in solar SMR and hybrid solar-redox processes is estimated to result in up to 85% reduction in life-cycle CO2 emission for hydrogen production as well as 99–122% methane to fuel conversion efficiency. Compared to the reforming-based schemes, the hybrid solar-redox process offers flexibility and 6.5–8% higher equivalent efficiency for liquid fuel and hydrogen co-production. While a number of operational parameters such as solar absorption efficiency, steam to methane ratio, operating pressure, and steam conversion can affect the process performances, solar energy integrated methane conversion processes have the potential to be efficient and environmentally friendly for hydrogen (and liquid fuel) production.}, number={31}, journal={INTERNATIONAL JOURNAL OF HYDROGEN ENERGY}, author={He, Feng and Li, Fanxing}, year={2014}, month={Oct}, pages={18092–18102} }
 @article{chen_galinsky_wang_li_2014, title={Investigation of perovskite supported composite oxides, for chemical looping conversion of syngas}, volume={134}, ISSN={["1873-7153"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84903579385&partnerID=MN8TOARS}, DOI={10.1016/j.fuel.2014.06.017}, abstractNote={In typical chemical looping processes, a transition metal oxide based oxygen carrier is used to indirectly convert carbonaceous fuels into concentrated CO2 and carbon free products through cyclic redox reactions. Among the various oxygen carrier candidates, iron oxide represents a promising option due to its abundance, low cost, and unique thermodynamic properties. A key challenge for ferrite based oxygen carriers resides in their low redox activity. In the current study, composite iron oxides with three types of mixed ionic–electronic conductive (MIEC) supports, i.e. lanthanum strontium ferrite (Sr-substituted lanthanum ferrite or LSF), barium cerium ferrite (Ce-substituted barium ferrite, BCF) and calcium titanate ferrite (Fe-substituted calcium titanate, CTF), are synthesized using solid state reaction (SSR) and sol–gel methods. Among the three MIEC materials, CTF support is found to possess superior structural stability. MIEC supported oxygen carriers are found to be significantly more active than a reference, yttrium-stabilized zirconia (YSZ) supported oxygen carrier. Higher support conductivity and smaller iron oxide precursor sizes generally lead to enhanced oxygen carrier activity. In contrast, surface area of the oxygen carrier is weakly correlated with its redox activity. CTF, although less conductive compared to BCF and LSF, is stable and sufficiently effective in shuttling active O2− and electrons for syngas oxidation and iron oxide regeneration. Therefore, CTF supported ferrites can potentially be a cost-effective oxygen carrier candidate for chemical looping processes. Further improvements in redox activity of the oxygen carriers can be achieved through iron oxide particle size reduction and support conductivity enhancement.}, journal={FUEL}, author={Chen, Yanguang and Galinsky, Nathan and Wang, Ziren and Li, Fanxing}, year={2014}, month={Oct}, pages={521–530} }
 @book{li_chen_2014, title={Mixed-Conductor Enhanced Composite and Core-Shell Oxides for Cyclic Redox Productions of Fuels and Chemicals}, number={US10486143B2}, author={Li, Fanxing and Chen, Yanguang}, year={2014} }
 @article{pressley_aziz_decarolis_barlaz_he_li_damgaard_2014, title={Municipal solid waste conversion to transportation fuels: a life-cycle estimation of global warming potential and energy consumption}, volume={70}, ISSN={["1879-1786"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84898919815&partnerID=MN8TOARS}, DOI={10.1016/j.jclepro.2014.02.041}, abstractNote={This paper utilizes life cycle assessment (LCA) methodology to evaluate the conversion of U.S. municipal solid waste (MSW) to liquid transportation fuels via gasification and Fischer-Tropsch (FT). The model estimates the cumulative energy demand and global warming potential (GWP) associated with the conversion of 1 Mg (1 Mg = 1000 kg) of MSW delivered to the front gate of a refuse-derived fuel (RDF) facility into liquid transportation fuels. In addition, net energy production is reported to quantify system performance. The system is expanded to include substituted electricity and fuel. Under a set of default assumptions, the model estimates that 1 Mg of MSW entering the RDF facility yields 123 L of gasoline, 57 L of diesel, 79 kg of other FT products, and 193 kWh of gross electricity production. For each Mg of MSW, the conversion process consumes 4.4 GJ of primary energy while creating fuels and electricity with a cumulative energy content of 10.8 GJ. Across a range of waste compositions, the liquid fuels produced by gasification and FT processing resulted in a net GWP ranging from −267 to −144 kg CO2e per Mg MSW, including offsets for conventional electricity and fuel production. The energy requirement associated with syngas compression for FT processing was significant and resulted in high levels of process-related GWP. The model demonstrates that an increased biogenic MSW fraction, assumed to be carbon neutral, reduced the GWP. However, a greater GWP reduction could be obtained through reduced FT pressure requirements, increased gas reaction rates, or a less carbon intensive power mix.}, journal={JOURNAL OF CLEANER PRODUCTION}, author={Pressley, Phillip N. and Aziz, Tarek N. and DeCarolis, Joseph F. and Barlaz, Morton A. and He, Feng and Li, Fanxing and Damgaard, Anders}, year={2014}, month={May}, pages={145–153} }
 @book{sofranko_li_neal_2014, title={Oxygen Transfer Agents for the Oxidative Dehydrogenation of Hydrocarbons and Systems and Processes Using the Same}, number={US10138182B2}, author={Sofranko, John and Li, Fanxing and Neal, Luke}, year={2014} }
 @article{li_li_2014, title={Preface to Special Issue CO2 Capture, Sequestration, Conversion and Utilization}, volume={14}, ISSN={["2071-1409"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894628122&partnerID=MN8TOARS}, DOI={10.4209/aaqr.2014.14.0001}, abstractNote={ABSTRACTThis special issue in Aerosol and Air Quality Research features selected papers presented at the Symposium on CO2 Capture, Sequestration, Conversion and Utilization, during the 245th American Chemical Society (ACS) National Meeting & Exposition, which was held in New Orleans, Louisiana, USA, from April 7 to 11, 2013. The symposium was organized by Prof. Ying Li at the University of Wisconsin-Milwaukee and Prof. Fanxing Li at North Carolina State University. It was the largest symposium among the twenty symposia within the Division of Energy and Fuels at the 245th ACS National Meeting & Exposition. A total of 80 invited and contributed talks were presented at the symposium. Topics included fundamentals in CO2 activation and advanced processes and materials for CO2 capture, sequestration, conversion, and utilization.
Anthropogenic CO2 emission from fossil energy conversion is one of the major contributors to global climate change. With projected increase in global energy consumption, advanced carbon capture, sequestration, and utilization approaches need to be developed. As a first step for CO2 mitigation, carbon capture can potentially be achieved, in a cost-effective manner, through new technologies that reduce the energy consumptions for separating diluted CO2 from conventional power plant flue gas. Alternatively, smart combustion or gasification processes such as oxy-fuel or chemical-looping are capable of producing concentrated CO2 for easy capture. Successful development and deployment of these aforementioned technologies require breakthroughs in advanced materials as well as innovative reactor concepts and process schemes. Sequestration of captured CO2 into geological formations such as saline aquifers is the next important step to ensure long term storage of CO2. Besides sequestration, a number of emerging ideas have shown promise to recycle and utilize CO2 as a carbon source for clean energy carriers or chemicals, mainly through catalytic processes. While CO2 is thermodynamically stable, renewable energy sources like solar can accomplish the challenging task of CO2 conversion and utilization. For example, it has been demonstrated that nanostructured photocatalysts are capable of converting CO2 and water into C1 fuels like CO, methane or methanol under solar radiation. Extensive research efforts are underway to enhance the CO2 conversion efficiency using these novel photocatalytic processes.}, number={2}, journal={AEROSOL AND AIR QUALITY RESEARCH}, author={Li, Ying and Li, Fanxing}, year={2014}, month={Mar}, pages={451–452} }
 @article{chen_he_daga_li_2014, title={Redox conversion of methane with Fe<inf>2</inf>O<inf>3</inf>- CaTi<inf>x</inf>M<inf>1(x</inf>O<inf>3</inf> composite oxides for hydrogen and liquid fuel co-production}, volume={65}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904906912&partnerID=MN8TOARS}, DOI={10.3969/j.issn.0438-1157.2014.07.035}, number={7}, journal={Huagong Xuebao/CIESC Journal}, author={Chen, Y. and He, F. and Daga, S. and Li, F.}, year={2014}, pages={2741–2750} }
 @article{he_galinsky_li_2013, title={Chemical looping gasification of solid fuels using bimetallic oxygen carrier particles - Feasibility assessment and process simulations}, volume={38}, ISSN={["1879-3487"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84879093997&partnerID=MN8TOARS}, DOI={10.1016/j.ijhydene.2013.04.054}, abstractNote={The chemical looping gasification (CLG) process utilizes an iron-based oxygen carrier to convert carbonaceous fuels into hydrogen and electricity while capturing CO2. Although the process has the potential to be efficient and environmentally friendly, the activity of the iron-based oxygen carrier is relatively low, especially for solid fuel conversion. In the present study, we propose to incorporate a secondary oxygen carrying metal oxide, i.e. CuO, to the iron-based oxygen carrier. Using the “oxygen-uncoupling” characteristics of CuO, gaseous oxygen is released at a high temperature to promote the conversion of both Fe2O3 and coal. Experiments carried out using a Thermal-Gravimetric Analyzer (TGA) indicate that a bimetallic oxygen carrier consisting of a small amount (5% by weight) of CuO is more effective for coal char conversion when compared to oxygen carrier without copper addition. ASPEN Plus® simulations and mathematical modeling of the process indicate that the incorporation of a small amount of copper leads to increased hydrogen yield and process efficiency.}, number={19}, journal={INTERNATIONAL JOURNAL OF HYDROGEN ENERGY}, author={He, Feng and Galinsky, Nathan and Li, Fanxing}, year={2013}, month={Jun}, pages={7839–7854} }
 @inproceedings{galinsky_he_li_2013, title={Development of Fe-Cu oxygen carriers for solid fuel gasification and hydrogen production}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84911890253&partnerID=MN8TOARS}, booktitle={Engineering Sciences and Fundamentals 2013 - Core Programming Area at the 2013 AIChE Annual Meeting: Global Challenges for Engineering a Sustainable Future}, author={Galinsky, N. and He, F. and Li, F.}, year={2013} }
 @book{li_hu_liu_wiltberger_peng_ferguson_2013, title={Gas Delivery Devices and Associated Systems and Methods}, number={US10023831B2}, author={Li, Fanxing and Hu, Weiwei and Liu, Yang and Wiltberger, Kelly and Peng, Haofan and Ferguson, Rachel}, year={2013} }
 @article{galinsky_huang_shafiefarhood_li_2013, title={Iron Oxide with Facilitated O2- Transport for Facile Fuel Oxidation and CO2 Capture in a Chemical Looping Scheme}, volume={1}, ISSN={["2168-0485"]}, DOI={10.1021/sc300177j}, abstractNote={The chemical looping strategy offers a potentially viable option for efficient carbonaceous fuel conversion with a reduced carbon footprint. In the chemical looping process, an oxygen carrier is reduced and oxidized in a cyclic manner to convert a carbonaceous fuel into separate streams of concentrated carbon dioxide and carbon-free products such as electricity and/or hydrogen. The reactivity and chemical and physical stability of the oxygen carrier are of pivotal importance to chemical looping processes. A typical oxygen carrier is composed of a multi-valence transition metal oxide supported on an “inert” support. Although the support does not get reduced or oxidized at any significant extent, numerous studies have indicated that certain supports such as TiO2 and Al2O3 can improve oxygen carrier stability and/or reactivity. This study reports the use of mixed ionic–electronic conductive support in iron-based oxygen carriers. By incorporating a perovskite-based mixed conductive support such as lanthanum s...}, number={3}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Galinsky, Nathan L. and Huang, Yan and Shafiefarhood, Arya and Li, Fanxing}, year={2013}, month={Mar}, pages={364–373} }
 @article{galinsky_huang_shafiefarhood_li_2013, title={Iron oxide with facilitated O<sup>2-</sup> transport for facile fuel oxidation and CO<inf>2</inf> capture in a chemical looping scheme}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84884212784&partnerID=MN8TOARS}, DOI={10.1021/sc300177}, number={3}, journal={ACS Sustainable Chemistry and Engineering}, author={Galinsky, N.L. and Huang, Y. and Shafiefarhood, A. and Li, F.}, year={2013}, pages={364–373} }
 @article{liang_feng_li_fan_2012, title={Chemical looping technology and its applications in fossil fuel conversion and CO2 capture}, volume={743}, number={2}, journal={Science China Chemistry}, author={Liang, Z. and Feng, H. and Li, F. and Fan, L.-S.}, year={2012}, pages={260–281} }
 @article{zeng_he_li_fan_2012, title={Coal-Direct Chemical Looping Gasification for Hydrogen Production: Reactor Modeling and Process Simulation}, volume={26}, ISSN={0887-0624 1520-5029}, url={http://dx.doi.org/10.1021/ef3003685}, DOI={10.1021/ef3003685}, abstractNote={A novel process scheme for hydrogen production from coal with in situ CO2 capture, known as the coal-direct chemical looping (CDCL) gasification process, is discussed in this article. The CDCL process utilizes an iron oxide based oxygen carrier as a chemical looping medium to indirectly gasify coal into separate streams of H2 and CO2. ASPEN Plus reactor simulation models based on both thermodynamic equilibrium limitations and kinetic limitations are developed to analyze individual CDCL reactors. Process simulations are subsequently performed to estimate the performance of the CDCL process under various mass and energy management schemes. Reactor modeling results indicate that a moving bed reducer can effectively convert coal while reducing the oxygen carrier. The reduced oxygen carrier can in turn be oxidized by steam to produce hydrogen in a moving bed oxidizer. The fates of pollutants as well as the effects of various process operating parameters such as carbon and iron oxide conversions are also evalua...}, number={6}, journal={Energy & Fuels}, publisher={American Chemical Society (ACS)}, author={Zeng, Liang and He, Feng and Li, Fanxing and Fan, Liang-Shih}, year={2012}, month={May}, pages={3680–3690} }
 @article{sridhar_tong_kim_zeng_li_fan_2012, title={Syngas Chemical Looping Process: Design and Construction of a 25 kWth Subpilot Unit}, volume={26}, ISSN={0887-0624 1520-5029}, url={http://dx.doi.org/10.1021/ef202039y}, DOI={10.1021/ef202039y}, abstractNote={The syngas chemical looping (SCL) process employing the gas–solid counter-current flow pattern demonstrates an innovative approach to generate hydrogen and/or electricity from syngas accompanied with in situ carbon capture. Iron-based oxygen carriers donate oxygen for complete syngas conversion in the reducer. The reduced oxygen carriers are then oxidized by steam and/or air to generate hydrogen and/or heat in the oxidizer and/or the combustor, respectively. Previous studies have reported the performance of the iron-based oxygen carriers, the advantages of a moving bed reducer and oxidizer, and simulation of various parametric effects on the reactor design of the reducer, oxidizer, and combustor for a continuous system. In this study, a 25 kWth subpilot SCL unit was designed based on the simulated criteria and constructed to demonstrate the feasibility of generating high purity hydrogen with in situ carbon capture. Two test runs were presented using 4.5 mm × 2.5–4.5 mm cylindrical oxygen carriers comprisi...}, number={4}, journal={Energy & Fuels}, publisher={American Chemical Society (ACS)}, author={Sridhar, Deepak and Tong, Andrew and Kim, Hyung and Zeng, Liang and Li, Fanxing and Fan, Liang-Shih}, year={2012}, month={Mar}, pages={2292–2302} }
 @inproceedings{zhou_zeng_yang_yu_wang_li_fan_2011, title={1-D dynamic modeling for moving bed reducer in chemical looping process}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84877616011&partnerID=MN8TOARS}, booktitle={28th Annual International Pittsburgh Coal Conference 2011, PCC 2011}, author={Zhou, Q. and Zeng, L. and Yang, H. and Yu, Z. and Wang, D. and Li, F. and Fan, L.-S.}, year={2011}, pages={1210–1222} }
 @article{sun_yu_li_li_fan_2011, title={Experimental Study of HCl Capture Using CaO Sorbents: Activation, Deactivation, Reactivation, and Ionic Transfer Mechanism}, volume={50}, ISSN={["0888-5885"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79955917323&partnerID=MN8TOARS}, DOI={10.1021/ie102587s}, abstractNote={Experimental study of dry HCl removal from synthesis gas or flue gas using CaO sorbents, in the context of CaO-based chemical looping processes, is reported. The study was first conducted in a TGA and a fixed-bed reactor to test the effects of chloridation temperature, sorbent particle size, HCl concentration, and space velocity on the HCl capture capacity. The chloridation reactivity deterioration of CaO sorbents with multicyclic carbonation−calcination reaction (CCR) and/or at high calcination temperatures, which are of notable relevance to the CaO-based chemical looping processes, was also investigated. In addition, precipitation (activation) and hydration (reactivation) were used to enhance initial sorbent reactivity and to reactivate the deactivated sorbents, respectively. The effects of deactivation, activation, and reactivation were explained by the morphological property change of the sorbents. To further elucidate the solid phase reaction mechanism of CaO and HCl, ionic transfer behavior during c...}, number={10}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Sun, Zhenchao and Yu, Fu-Chen and Li, Fanxing and Li, Songgeng and Fan, Liang-Shih}, year={2011}, month={May}, pages={6034–6043} }
 @inproceedings{luo_sun_li_sridhar_zeng_fan_2011, title={Investigation of oxygen diffusivity within oxygen carrier in chemical looping process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863396922&partnerID=MN8TOARS}, booktitle={11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings}, author={Luo, S. and Sun, Z. and Li, F. and Sridhar, D. and Zeng, L. and Fan, L.-S.}, year={2011}, pages={169} }
 @article{li_sun_luo_fan_2011, title={Ionic diffusion in the oxidation of iron-effect of support and its implications to chemical looping applications}, volume={4}, ISSN={["1754-5706"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79952435405&partnerID=MN8TOARS}, DOI={10.1039/c0ee00589d}, abstractNote={Addition of TiO2 was found to significantly enhance the ionic diffusivity of O anion within iron and its oxides, thereby changing the dominating ionic transfer mechanism for iron oxidation from “outward Fe cation diffusion” (in pure Fe case) to “inward O anion diffusion” (in Fe with TiO2 support case).}, number={3}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={Li, Fanxing and Sun, Zhenchao and Luo, Siwei and Fan, Liang-Shih}, year={2011}, month={Mar}, pages={876–880} }
 @inproceedings{kim_li_wang_sridhar_zeng_tong_wang_sun_luo_fan_2011, title={Iron-based chemical looping process for coal conversion}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80051879079&partnerID=MN8TOARS}, booktitle={ACS National Meeting Book of Abstracts}, author={Kim, R. and Li, F. and Wang, D. and Sridhar, D. and Zeng, L. and Tong, A.S. and Wang, F. and Sun, Z. and Luo, S. and Fan, L.-S.}, year={2011} }
 @book{fan_sridhar_li_2011, title={Oxygen Carrying Materials}, number={US10502414B2, CN103635673B, AU2012253332B2, CA2835421A1, EP3584426A1}, author={Fan, L.-S. and Sridhar, Deepak and Li, Fanxing}, year={2011} }
 @inproceedings{zeng_li_sridhar_kim_tong_luo_fan_2011, title={Process integration and analysis of chemical looping based power and fuel generation systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863127295&partnerID=MN8TOARS}, booktitle={11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings}, author={Zeng, L. and Li, F. and Sridhar, D. and Kim, H.R. and Tong, A. and Luo, S. and Fan, L.-S.}, year={2011} }
 @article{li_luo_sun_bao_fan_2011, title={Role of metal oxide support in redox reactions of iron oxide for chemical looping applications: experiments and density functional theory calculations}, volume={4}, ISSN={["1754-5706"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80052249355&partnerID=MN8TOARS}, DOI={10.1039/c1ee01325d}, abstractNote={Aided by an oxygen carrier such as iron oxide, the chemical looping process can convert carbonaceous fuels while effectively capturing CO2. Previous experimental studies indicate that adding TiO2 support to iron oxide can notably improve the reactivity of iron oxide over multiple redox cycles, making it more suitable for chemical looping applications. In this study, wustite (Fe1−xO) was used to represent pure iron(II) oxide and ilmenite (FeTiO3) was used to represent TiO2 supported iron(II) oxide. The underlying mechanisms for the improved iron oxide performance with TiO2 support are investigated through experiments and periodic Density Functional Theory (DFT) calculations. Both experimental and DFT studies indicate that TiO2 support is unlikely to reduce the activation energy for the reduction of iron(II) oxide. The support, however, can significantly lower the energy barrier for O2− migration within the dense solid phase, thereby enhancing the O2− diffusivity. The good agreements between experiments and DFT calculations confirm that the improved reactivity and recyclability of TiO2 supported iron oxide particles are likely to result from the significantly enhanced O2− diffusivity with the presence of support.}, number={9}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={Li, Fanxing and Luo, Siwei and Sun, Zhenchao and Bao, Xiaoguang and Fan, Liang-Shih}, year={2011}, month={Sep}, pages={3661–3667} }
 @book{fan_kim_li_zeng_wang_wang_2011, title={Systems for Converting Fuel}, number={US9903584B2}, author={Fan, L.-S. and Kim, Hyung R. and Li, Fanxing and Zeng, Liang and Wang, Dawei and Wang, Fei}, year={2011} }
 @article{li_sun_zeng_fan_2010, title={Biomass Direct Chemical Looping Process: Process Simulations}, volume={89}, number={12}, journal={Fuel }, author={Li, F. and Sun, Z and Zeng, L. and Fan, L.-S.}, year={2010}, pages={3773–3784} }
 @article{li_zeng_fan_2010, title={Biomass direct chemical looping process: Process simulation}, volume={89}, ISSN={0016-2361}, url={http://dx.doi.org/10.1016/j.fuel.2010.07.018}, DOI={10.1016/j.fuel.2010.07.018}, abstractNote={Biomass is a clean and renewable energy source. The efficiency for biomass conversion using conventional fuel conversion techniques, however, is constrained by the relatively low energy density and high moisture content of biomass. This study presents the biomass direct chemical looping (BDCL) process, an alternative process, which has the potential to thermochemically convert biomass to hydrogen and/or electricity with high efficiency. Process simulation and analysis are conducted to illustrate the individual reactor performance and the overall mass and energy management scheme of the BDCL process. A multistage model is developed based on ASPEN Plus® to account for the performance of the moving bed reactors considering the reaction equilibriums. The optimum operating conditions for the reactors are also determined. Process simulation utilizing ASPEN Plus® is then performed based on the reactor performance data obtained from the multistage model. The simulation results indicate that the BDCL process is significantly more efficient than conventional biomass conversion processes. Moreover, concentrated CO2, produced from the BDCL process is readily sequesterable, making the process carbon negative. Several BDCL configurations are investigated for process optimization purposes. The fates of contaminants are also examined.}, number={12}, journal={Fuel}, publisher={Elsevier BV}, author={Li, Fanxing and Zeng, Liang and Fan, Liang-Shih}, year={2010}, month={Dec}, pages={3773–3784} }
 @book{li_wang_sridhar_kim_velazquez-vargas_fan_2010, title={Chemical Looping Combustion}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84886080328&partnerID=MN8TOARS}, DOI={10.1002/9780470872888.ch3}, abstractNote={This chapter contains sections titled: Introduction CO2 Capture Strategies for Fossil Fuel Combustion Power Plants Chemical Looping Combustion Concluding Remarks References}, journal={Chemical Looping Systems for Fossil Energy Conversions}, author={Li, F. and Wang, F. and Sridhar, D. and Kim, H.R. and Velazquez-Vargas, L.G. and Fan, L.-S.}, year={2010}, pages={143–214} }
 @book{li_zeng_ramkumar_sridhar_iyer_fan_2010, title={Chemical Looping Gasification Using Gaseous Fuels}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84855297823&partnerID=MN8TOARS}, DOI={10.1002/9780470872888.ch4}, abstractNote={This chapter contains sections titled: Introduction Traditional Coal Gasification Processes Iron-Based Chemical Looping Processes Using Gaseous Fuels Design, Analysis and Optimization of the Syngas Chemical Looping (SCL) Process Process Simulation of the Traditional Gasification Process and the Syngas Chemical Looping Process Example of SCL Applications—A Coal-to-Liquid Configuration Calcium Looping Process Using Gaseous Fuels Concluding Remarks References}, journal={Chemical Looping Systems for Fossil Energy Conversions}, author={Li, F. and Zeng, L. and Ramkumar, S. and Sridhar, D. and Iyer, M. and Fan, L.-S.}, year={2010}, pages={215–300} }
 @book{li_zeng_sridhar_velazquez-vargas_fan_2010, title={Chemical Looping Gasification Using Solid Fuels}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84886029323&partnerID=MN8TOARS}, DOI={10.1002/9780470872888.ch5}, abstractNote={This chapter contains sections titled: Introduction Chemical Looping Gasification Processes Using Calcium-Based Sorbent Coal-Direct Chemical Looping (CDCL) Processes Using Iron - Based Oxygen Carriers Challenges to the Coal-Direct Chemical Looping Processes and Strategy for Improvements Process Simulation on the Coal-Direct Chemical Looping Process Concluding Remarks References}, journal={Chemical Looping Systems for Fossil Energy Conversions}, author={Li, F. and Zeng, L. and Sridhar, D. and Velazquez-Vargas, L.G. and Fan, L.-S.}, year={2010}, pages={301–361} }
 @book{gupta_li_velázquez-vargas_sridhar_iyer_ramkumar_fan_2010, title={Chemical Looping Particles}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84886023297&partnerID=MN8TOARS}, DOI={10.1002/9780470872888.ch2}, abstractNote={This chapter contains sections titled: Introduction Type I Chemical Looping System Type II Chemical Looping System Concluding Remarks References}, journal={Chemical Looping Systems for Fossil Energy Conversions}, author={Gupta, P. and Li, F. and Velázquez-Vargas, L. and Sridhar, D. and Iyer, M. and Ramkumar, S. and Fan, L.-S.}, year={2010}, pages={57–142} }
 @article{fan_li_2010, title={Chemical Looping Technology and Its Fossil Energy Conversion Applications}, volume={49}, ISSN={["0888-5885"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78049401610&partnerID=MN8TOARS}, DOI={10.1021/ie1005542}, abstractNote={The concept of chemical looping reactions has been widely applied in chemical industries, for example, the production of hydrogen peroxide (H2O2) from hydrogen and oxygen using 9,10-anthraquinone as the looping intermediate. Fundamental research on chemical looping reactions has also been applied to energy systems, for example, the splitting of water (H2O) to produce oxygen and hydrogen using ZnO as the looping intermediate. Fossil fuel chemical looping applications had been used commercially with the steam-iron process for coal from the 1900s to the 1940s and had been demonstrated at a pilot scale with the carbon dioxide acceptor process in the 1960s and 1970s. There are presently no chemical looping processes using fossil fuels in commercial operation. A key factor that hampered the continued use of these earlier processes for fossil energy operation was the inadequacy of the reactivity and recyclability of the looping particles. This factor led to higher costs for product generation using the chemical ...}, number={21}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Fan, Liang-Shih and Li, Fanxing}, year={2010}, month={Nov}, pages={10200–10211} }
 @book{fan_li_wang_tong_karri_findlay_knowlton_cocco_2010, title={Circulating Fluidized Bed with Moving Bed Downcomers and Gas Sealing Between Reactors}, number={US10010847B2, CA2816800C, CN103354763B, AU201132612B2}, author={Fan, L.-S. and Li, Fanxing and Wang, Fei and Tong, Andrew and Karri, Reddy and Findlay, John and Knowlton, Ted and Cocco, Ray}, year={2010} }
 @book{park_gupta_li_sridhar_fan_2010, title={Novel Applications of Chemical Looping Technologies}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84885994878&partnerID=MN8TOARS}, DOI={10.1002/9780470872888.ch6}, abstractNote={As discussed in the previous chapters, the Type I chemical looping process (see Chapter 2) uses a metal/metal oxide particle with a specially designed support and promoters that can undergo multiple (> 100) reduction/oxidation cycles while maintaining a high oxygen-carrying capacity. These particles, in oxidized form, are capable of reacting with different kinds of carbonaceous fuels, such as coal, biomass, syngas, hydrocarbons, and wax, after which the particles are reduced to the metallic form. At the reduced state, particles can be oxidized to the original state by air, O 2 , CO 2 , or steam. Thus, these engineered chemical looping particles allow the effi cient conversion of various carbonaceous fuels to heat CO, H 2 , syngas, or any combination of these products. These particles also can be used in the production of steam, electricity, chemicals, or gaseous and liquid fuels. Furthermore, the particle reaction rate, because of the presence of promoter and support, can be an order of magnitude faster than the metal/metal oxide in its pure form. In addition, as mentioned in earlier chapters, the redox process in two different reactors also provides a built-in CO 2 separation feature. The Type II chemical looping process (see Chapter 2) uses metal oxide/ metal carbonate particles to capture CO 2 , sulfur, and halide impurities simultaneously over multiple cycles while maintaining a high capture capacity (0.5-g CO 2 captured per gram of metal oxide). The metal oxide particles are capable}, journal={Chemical Looping Systems for Fossil Energy Conversions}, author={Park, A.-H.A. and Gupta, P. and Li, F. and Sridhar, D. and Fan, L.-S.}, year={2010}, pages={363–401} }
 @article{li_sun_zeng_velazquez-vargas_yosevich_fan_2010, title={Syngas Chemical Looping Gasification Process: Bench-scale Studies and Reactor Simulations}, volume={56}, number={8}, journal={AIChE Journal}, author={Li, F. and Sun, Z and Zeng, L. and Velazquez-Vargas, L.G. and Yosevich, Z. and Fan, L.-S}, year={2010}, pages={2186–2199} }
 @article{li_zeng_velazquez-vargas_yoscovits_fan_2010, title={Syngas chemical looping gasification process: Bench-scale studies and reactor simulations}, volume={56}, ISSN={0001-1541}, url={http://dx.doi.org/10.1002/aic.12093}, DOI={10.1002/aic.12093}, abstractNote={The syngas chemical looping process co-produces hydrogen and electricity from syngas through the cyclic reduction and regeneration of an iron oxide based oxygen carrier. In this article, the reducer, which reduces the oxygen carrier with syngas, is investigated through thermodynamic analysis, experiments, and ASPEN Plus® simulation. The thermodynamic analysis indicates that the countercurrent moving-bed reducer offers better gas and solids conversions when compared to the fluidized-bed reducer. The reducer is continuously operated for 15 h in a bench scale moving-bed reactor. A syngas conversion in excess of 99.5% and an oxygen carrier conversion of nearly 50% are obtained. An ASPEN Plus® model is developed which simulates the reducer performance. The results of simulation are consistent with those obtained from both the thermodynamic analysis and experiments. Both the experiments and simulation indicate that the proposed SCL reducer concept is feasible. © 2009 American Institute of Chemical Engineers AIChE J, 2010}, number={8}, journal={AIChE Journal}, publisher={Wiley}, author={Li, Fanxing and Zeng, Liang and Velazquez-Vargas, Luis G. and Yoscovits, Zachary and Fan, Liang-Shih}, year={2010}, month={Aug}, pages={2186–2199} }
 @article{li_zeng_fan_2010, title={Techno-Economic Analysis of Coal-Based Hydrogen and Electricity Cogeneration Processes with CO2 Capture}, volume={49}, ISSN={["0888-5885"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78049407317&partnerID=MN8TOARS}, DOI={10.1021/ie100568z}, abstractNote={The techno-economic performances of various coal-based hydrogen and electricity cogeneration processes are examined under a carbon-constrained scenario. The baseline coal gasification process and the novel membrane and syngas chemical-looping processes are evaluated. Aspen Plus simulation is first performed to analyze the process efficiencies on the basis of a common set of assumptions. This is followed by economic analysis using the cost analysis principles suggested by the U.S. Department of Energy [Cost and Performance Baseline for Fossil Energy Plants, 2007]. The results indicate that the novel membrane and syngas chemical-looping strategies have the potential to notably reduce the energy and cost penalties for CO2 capture in coal conversion processes.}, number={21}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Li, Fanxing and Zeng, Liang and Fan, Liang-Shih}, year={2010}, month={Nov}, pages={11018–11028} }
 @inproceedings{zeng_li_kim_sridhar_wang_tong_sun_nobusuke_fan_2009, title={Biomass conversion via direct chemical looping technology - Process simulations}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77951695380&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Zeng, L. and Li, F. and Kim, R.H. and Sridhar, D. and Wang, F. and Tong, A. and Sun, Z. and Nobusuke, K. and Fan, L.S.}, year={2009} }
 @inproceedings{sridhar_li_tong_kim_zeng_wang_fan_2009, title={Coal-derived products: Hydrogen production syngas chemical looping: Road to sub-pilot scale demonstrations}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84877659226&partnerID=MN8TOARS}, booktitle={26th Annual International Pittsburgh Coal Conference 2009, PCC 2009}, author={Sridhar, D. and Li, F. and Tong, A. and Kim, R. and Zeng, L. and Wang, F. and Fan, L.-S.}, year={2009}, pages={1039–1049} }
 @book{fan_li_2009, title={Conversion of Carbonaceous Fuels into Carbon Free Energy Carriers}, number={US8877147B2}, author={Fan, L.-S. and Li, Fanxing}, year={2009} }
 @inproceedings{tong_li_sridhar_zeng_wang_kim_fan_2009, title={Design of the syngas chemical looping sub-pilot scale unit}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84877646835&partnerID=MN8TOARS}, booktitle={26th Annual International Pittsburgh Coal Conference 2009, PCC 2009}, author={Tong, A. and Li, F. and Sridhar, D. and Zeng, L. and Wang, F. and Kim, H.R. and Fan, L.-S.}, year={2009}, pages={474–478} }
 @inproceedings{kim_li_sridhar_zeng_tong_kobayashi_fan_2009, title={Exact title of paper: Chemical looping combustion of coal and woody biomass}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84877683156&partnerID=MN8TOARS}, booktitle={26th Annual International Pittsburgh Coal Conference 2009, PCC 2009}, author={Kim, H.R. and Li, F. and Sridhar, D. and Zeng, L. and Tong, A. and Kobayashi, N. and Fan, L.-S.}, year={2009}, pages={466–473} }
 @book{fan_li_zeng_sridhar_2009, title={Integration of Reforming/Water Splitting and Electrochemical Systems for Power Generation with Integrated Carbon Capture}, number={US13394572B2 AU2010292313 EPO2010760504}, author={Fan, L.-S. and Li, Fanxing and Zeng, Liang and Sridhar, Deepak}, year={2009} }
 @article{li_kim_sridhar_wang_zeng_chen_fan_2009, title={Syngas Chemical Looping Gasification Process: Oxygen Carrier Particle Selection and Performance}, volume={23}, ISSN={0887-0624 1520-5029}, url={http://dx.doi.org/10.1021/ef900236x}, DOI={10.1021/ef900236x}, abstractNote={The syngas chemical looping (SCL) process coproduces hydrogen and electricity. The process involves reducing metal oxides with syngas followed by regeneration of reduced metal oxides with steam and air in a cyclic manner. Iron oxide is determined to be a desired oxygen carrier for hydrogen production considering overall properties including oxygen carrying capacity, thermodynamic properties, reaction kinetics, physical strength, melting points, and environmental effects. An iron oxide based particle can maintain good reactivity for more than 100 reduction−oxidation (redox) cycles in a thermogravimetric analyzer (TGA). The particle exhibits a good crushing strength (>20 MPa) and low attrition rate. Fixed bed experiments are carried out which reaffirm its reactivity. More than 99.75% of syngas is converted during the reduction stage. During the regeneration stage, hydrogen with an average purity of 99.8% is produced.}, number={8}, journal={Energy & Fuels}, publisher={American Chemical Society (ACS)}, author={Li, Fanxing and Kim, Hyung Ray and Sridhar, Deepak and Wang, Fei and Zeng, Liang and Chen, Joseph and Fan, L.-S.}, year={2009}, month={Aug}, pages={4182–4189} }
 @inproceedings{li_sridhar_kim_zeng_tong_wang_fan_2009, title={Syngas chemical looping gasification process for hydrogen production}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77951584147&partnerID=MN8TOARS}, booktitle={8th World Congress of Chemical Engineering: Incorporating the 59th Canadian Chemical Engineering Conference and the 24th Interamerican Congress of Chemical Engineering}, author={Li, F. and Sridhar, D. and Kim, H. and Zeng, L. and Tong, A. and Wang, F. and Fan, L.-S.}, year={2009} }
 @book{fan_li_zeng_2009, title={Synthetic Fuels and Chemicals Production with in-situ CO2 Capture}, number={US9518236B2}, author={Fan, L.-S. and Li, Fanxing and Zeng, Liang}, year={2009} }
 @inproceedings{fan_li_velazquez-vargas_ramkumar_2008, title={Chemical looping gasification}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904821279&partnerID=MN8TOARS}, booktitle={CFB 2008 - Proceedings of the 9th Int. Conference on Circulating Fluidized Beds, in Conjunction with the 4th International VGB Workshop "Operating Experience with Fluidized Bed Firing Systems"}, author={Fan, L.-S. and Li, F. and Velazquez-Vargas, L.G. and Ramkumar, S.}, year={2008} }
 @article{li_fan_2008, title={Clean coal conversion processes – progress and challenges}, volume={1}, ISSN={1754-5692 1754-5706}, url={http://dx.doi.org/10.1039/b809218b}, DOI={10.1039/b809218b}, abstractNote={Although the processing of coal is an ancient problem and has been practiced for centuries, the constraints posed on today's coal conversion processes are unprecedented, and utmost innovations are required for finding the solution to the problem.With a strong demand for an affordable energy supply which is compounded by the urgent need for a CO2 emission control, the clean and efficient utilization of coal presents both a challenge and an opportunity to the current global R&D efforts in this area. This paper provides a historical perspective on the utilization of coal as an energy source as well as describing the progress and challenges and the future prospect of clean coal conversion processes. It provides background on the historical utilization of coal as an energy source, along with particular emphasis on the constraints in current coal conversion technologies. It addresses the energy conversion efficiencies for current coal combustion and gasification processes and for the membrane and looping based novel processes which are currently under development at various stages of testing. The control technologies for pollutants including CO2 in flue gas or syngas are also discussed. The coal conversion process efficiencies under a CO2 constrained environment are illustrated based on data and ASPEN Plus® simulations. The challenges for future R&D efforts in novel coal conversion process development are also presented.}, number={2}, journal={Energy & Environmental Science}, publisher={Royal Society of Chemistry (RSC)}, author={Li, Fanxing and Fan, Liang-Shih}, year={2008}, pages={248–267} }
 @inproceedings{li_kim_sridhar_zeng_wang_fan_2008, title={Coal Direct Chemical Looping (CDCL) process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79952309196&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Li, F. and Kim, H. and Sridhar, D. and Zeng, L. and Wang, F. and Fan, L.-S.}, year={2008} }
 @inproceedings{kim_li_sridhar_zeng_wang_fan_2008, title={Coal direct chemical looping process for hydrogen production - Experimental studies}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349597170&partnerID=MN8TOARS}, booktitle={25th Annual International Pittsburgh Coal Conference, PCC - Proceedings}, author={Kim, H. and Li, F. and Sridhar, D. and Zeng, L. and Wang, F. and Fan, L.-S.}, year={2008} }
 @inproceedings{zeng_li_sridhar_wang_kim_fan_2008, title={Comparison of coal based hydrogen and electricity co-generation processes under a carbon constrained scenario}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79952301368&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Zeng, L. and Li, F. and Sridhar, D. and Wang, F. and Kim, H.R. and Fan, L.-S.}, year={2008} }
 @inproceedings{zeng_wang_li_yu_tong_fan_2008, title={Hydrogen production from coal direct chemical looping process-process simulation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349599344&partnerID=MN8TOARS}, booktitle={25th Annual International Pittsburgh Coal Conference, PCC - Proceedings}, author={Zeng, L. and Wang, F. and Li, F. and Yu, F.C. and Tong, A. and Fan, L.S.}, year={2008} }
 @inproceedings{wang_li_tong_sridhar_fan_2008, title={Particle size optimization for syngas chemical looping process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79952285828&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Wang, F. and Li, F. and Tong, A. and Sridhar, D. and Fan, L.-S.}, year={2008} }
 @inproceedings{sridhar_fan_li_kim_zeng_yeh_2008, title={Studies on the reduction mechanism of the iron oxide based composite particle in the ingas chemical looping process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349585239&partnerID=MN8TOARS}, booktitle={25th Annual International Pittsburgh Coal Conference, PCC - Proceedings}, author={Sridhar, D. and Fan, L.-S. and Li, F. and Kim, H. and Zeng, L. and Yeh, T.}, year={2008} }
 @inproceedings{li_sridhar_kim_zeng_wang_fan_2008, title={Syngas chemical looping process for hydrogen production}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70349590098&partnerID=MN8TOARS}, booktitle={25th Annual International Pittsburgh Coal Conference, PCC - Proceedings}, author={Li, F. and Sridhar, D. and Kim, H. and Zeng, L. and Wang, F. and Fan, L.-S.}, year={2008} }
 @inproceedings{li_sridhar_kim_zeng_wang_fan_2008, title={Syngas chemical looping process for hydrogen production: Bench scale demonstration and process simulation}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79952286256&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Li, F. and Sridhar, D. and Kim, H. and Zeng, L. and Wang, F. and Fan, L.-S.}, year={2008} }
 @article{fan_li_ramkumar_2008, title={Utilization of chemical looping strategy in coal gasification processes}, volume={6}, ISSN={1674-2001}, url={http://dx.doi.org/10.1016/j.partic.2008.03.005}, DOI={10.1016/j.partic.2008.03.005}, abstractNote={Abstract Three chemical looping gasification processes, i.e. Syngas Chemical Looping (SCL) process, Coal Direct Chemical Looping (CDCL) process, and Calcium Looping process (CLP), are being developed at the Ohio State University (OSU). These processes utilize simple reaction schemes to convert carbonaceous fuels into products such as hydrogen, electricity, and synthetic fuels through the transformation of a highly reactive, highly recyclable chemical intermediate. In this paper, these novel chemical looping gasification processes are described and their advantages and potential challenges for commercialization are discussed.}, number={3}, journal={Particuology}, publisher={Elsevier BV}, author={Fan, Liangshih and Li, Fanxing and Ramkumar, Shwetha}, year={2008}, month={Jun}, pages={131–142} }
 @inproceedings{fan_velazquez-vargas_li_2007, title={Chemical looping reforming Ppocess for the production of hydrogen from coal}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-37349080664&partnerID=MN8TOARS}, booktitle={ACS National Meeting Book of Abstracts}, author={Fan, L.S. and Velazquez-Vargas, L.G. and Li, F.}, year={2007} }
 @article{fan_li_2007, title={Clean coal}, volume={20}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34547305472&partnerID=MN8TOARS}, number={7}, journal={Physics World}, author={Fan, L.-S. and Li, F.}, year={2007}, pages={37–41} }
 @inproceedings{kim_park_velazquez-vargas_li_fan_2007, title={Enhanced hydrogen production with integrated carbon capture and sequestration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-58049103718&partnerID=MN8TOARS}, booktitle={2007 AIChE Annual Meeting}, author={Kim, H.R. and Park, A.-H.A. and Velazquez-Vargas, L.G. and Li, F. and Fan, L.-S.}, year={2007} }
 @inproceedings{velazquez-vargas_li_sirdar_kim_fan_2007, title={Enhanced production of liquid fuels by using a syngas chemical looping process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80053656406&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Velazquez-Vargas, L.G. and Li, F. and Sirdar, D. and Kim, R. and Fan, L.-S.}, year={2007} }
 @inproceedings{li_velazquez-vargas_zeng_chen_fan_2007, title={Exergy analysis on chemical looping reforming process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-58049127071&partnerID=MN8TOARS}, booktitle={2007 AIChE Annual Meeting}, author={Li, F. and Velazquez-Vargas, L.G. and Zeng, L. and Chen, J. and Fan, L.-S.}, year={2007} }
 @inproceedings{li_velazquez-vergas_zeng_chen_fan_2007, title={Exergy analysis on chemical looping reforming process}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80053655723&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Li, F. and Velazquez-Vergas, L.G. and Zeng, L. and Chen, J. and Fan, L.-S.}, year={2007} }
 @inproceedings{gupta_velazquez-vargas_li_fan_2006, title={Chemical looping reforming - an efficient process for the production of hydrogen from coal}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80053806002&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Gupta, P. and Velazquez-Vargas, L.G. and Li, F. and Fan, L.-S.}, year={2006} }
 @inproceedings{velazquez-vargas_gupta_li_fan_2006, title={Hydrogen production from coal derived syn gas using novel metal oxide particles}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34748871418&partnerID=MN8TOARS}, booktitle={23rd Annual International Pittsburgh Coal Conference, PCC - Coal-Energy, Environment and Sustainable Development}, author={Velazquez-Vargas, L.G. and Gupta, P. and Li, F. and Fan, L.-S.}, year={2006} }
 @inproceedings{velazquez-vargas_li_gupta_fan_2006, title={Reduction of metal oxide particles with syngas for hydrogen production}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-58049115719&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Velazquez-Vargas, L.G. and Li, F. and Gupta, P. and Fan, L.-S.}, year={2006} }
 @inproceedings{gupta_velazquez-vargas_li_fan_2005, title={Chemical looping combustion of coal}, volume={2005}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33645638139&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting, Conference Proceedings}, author={Gupta, P. and Velazquez-Vargas, L.G. and Li, F. and Fan, L.-S.}, year={2005}, pages={7620–7625} }
 @inproceedings{velazquez-vargas_gupta_li_fan_2005, title={Hydrogen production from syngas using metal oxide composite particles}, volume={2005}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33646750981&partnerID=MN8TOARS}, booktitle={AIChE Annual Meeting Conference Proceedings}, author={Velazquez-Vargas, L.G. and Gupta, P. and Li, F. and Fan, L.-S.}, year={2005}, pages={10119–10122} }
 @article{li_wang_wang_wei_2004, title={Characterization of single-wall carbon nanotubes by N2 adsorption}, volume={42}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/j.carbon.2004.02.025}, DOI={10.1016/j.carbon.2004.02.025}, abstractNote={N2 adsorption isotherms at 77 K of single-wall carbon nanotubes (SWNTs), multi-wall carbon nanotubes (MWNTs), and mixtures of these carbon nanotubes (CNTs) were analyzed for differences in their pore size distributions (PSDs). The PSDs, calculated in the microporous region by the Horvath–Kawazoe method and in the mesoporous region by the BJH method, are in agreement with the structures of both types of CNTs deduced from high-resolution transmission electron microscopy. A characteristic peak in the microporous region in the PSD of SWNTs is not present in the PSDs of MWNTs and impurities such as amorphous carbon, metal residues of catalysts, etc. The evaluation of this peak is proposed as a convenient tool for the quantitative characterization of SWNT purity in carbon nanotube-containing samples.}, number={12-13}, journal={Carbon}, publisher={Elsevier BV}, author={Li, Fanxing and Wang, Yao and Wang, Dezheng and Wei, Fei}, year={2004}, pages={2375–2383} }
 @book{zhao_li_wang_2004, title={Comparison of microkinetics and Langmuir-Hinshelwood models of the partial oxidation of methane to synthesis gas}, volume={147}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-9444252816&partnerID=MN8TOARS}, journal={Studies in Surface Science and Catalysis}, author={Zhao, X. and Li, F. and Wang, D.}, year={2004}, pages={235–240} }
 @article{wang_li_zhao_2004, title={Diffusion limitation in fast transient experiments}, volume={59}, ISSN={0009-2509}, url={http://dx.doi.org/10.1016/j.ces.2004.07.111}, DOI={10.1016/j.ces.2004.07.111}, abstractNote={Pulsed gas experiments show that during transient experiments on porous particles with response times which are even as slow as the seconds range, intraparticle diffusion is often not fast enough and concentration gradients exist inside the porous powders. This situation is detected when packed beds of different lengths give effective bed diffusivities that change with the bed length or when the use of a long (>2cm) packed bed gives a pulse shape for which a good fit cannot be obtained with a reactor model that assumes intraparticle diffusion is fast. The use of very small 200–400 mesh particles shows that intraparticle diffusion control is in the microparticles, and not in the macropores of the interstices between the microparticles of compacted bimodal particles. When intraparticle diffusion in the micropores is controlling, kinetics parameters obtained from transient experiments vary with the length of the packed bed used.}, number={22-23}, journal={Chemical Engineering Science}, publisher={Elsevier BV}, author={Wang, Dezheng and Li, Fanxing and Zhao, Xueliang}, year={2004}, month={Nov}, pages={5615–5622} }