@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{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{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{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={2}, 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{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{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{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{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={Chemical looping air separation has numerous potential benefits in terms of energy saving and emission reductions. The current study details a combination of density functional theory calculation and experimental efforts to design A and B-site co-doped SrFeO3 perovskites as "low temperature" oxygen sorbents for chemical looping air separation. Substitution of the SrFeO3 host structure with Ca and Co lowers oxygen vacancy formation energy by 0.24-0.46 eV and decreases the oxygen release temperature. As a result, Sr1-xCaxFe1-yCoyO3 (SCFC, x = 0.2, 0.0 < y < 1.0) spontaneously releases oxygen at 400-500 oC even under a relatively high oxygen partial pressure (e.g. PO2 = 0.05 atm). Sr0.8Ca0.2Fe0.4Co0.6O3 exhibits a significantly higher oxygen capacity of 1.2 w.t.% at 400 °C and under a PO2 swing between 0.05 and 0.2 atm, when compared to the <0.2 w.t.% capacity for un-doped a SrFeO3 (SF) and Ca doped Sr0.8Ca0.2FeO3 (SCF). Electrical conductivity relaxation (ECR) study demonstrates co-doping of Ca and Co lowers activation energy of oxygen diffusion and surface oxygen exchange by 26.6 and 137.9 kJ/mol accordingly, resulting in fast redox kinetics of SCFC comparing to SCF perovskite. The SCFC oxygen sorbent also exhibits excellent stability for 2000 redox cycling for air separation.}, 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{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{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{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} }