@article{ruan_yang_beckett_martin_walter_hu_liu_zayan_lessin_faherty_et al._2024, title={Metal-facilitated, sustainable nitroarene hydrogenation under ambient conditions}, volume={432}, ISSN={["1090-2694"]}, DOI={10.1016/j.jcat.2024.115428}, abstractNote={Hydrogenation is a critical reaction in the chemical industry, yielding a range of important compounds such as fine chemicals, pharmachemicals and agrochemicals. However, conventional hydrogenation typically requires pressurized hydrogen, high temperatures and involves noble metal catalysts. We proposed a two-step hydrogenation process, utilizing water as the hydrogen source for the industrially important reduction of nitroarenes to anilines. A metal or reduced metal oxide, which can be obtained from solar thermal or electrochemical reduction, acts as the active site for nitrobenzene adsorption, H2O dissociation and in-situ hydrogen generation. Among the 15 metal and reduced metal oxides investigated, Zn and Sn emerged as highly efficient catalysts for the reduction of a broad range of organic nitro compounds under mild conditions, with H2 utilization efficiency 1–2 orders of magnitude above the state-of-the-art. The presented protocol provides extra dimensions for designing and optimizing conventional hydrogenation process with an alternative pathway. The reactive hydrogen atoms generated in-situ effectively overcome the barriers associated with hydrogen gas dissolution and its subsequent dissociation on the catalyst surface, thereby greatly enhancing the overall effectiveness for the hydrogenation reaction. This research potentially establishes a sustainable, generally applicable alternative to conventional hydrogenation methods, simultaneously presenting a viable solution for renewable energy storage.}, journal={JOURNAL OF CATALYSIS}, author={Ruan, Chongyan and Yang, Kunran and Beckett, Caitlin and Martin, William and Walter, Eric D. and Hu, Wenda and Liu, Junchen and Zayan, Noha and Lessin, Benjamin and Faherty, Jacob Ken and et al.}, year={2024}, month={Apr} }
 @article{pedersen_liu_li_lamb_2024, title={MnO(001) thin films on MgO(001) grown by reactive MBE using supersonic molecular beams}, volume={160}, ISSN={["1089-7690"]}, url={https://doi.org/10.1063/5.0198832}, DOI={10.1063/5.0198832}, abstractNote={MnO(001) thin films were grown on commercial MgO(001) substrates at 520 °C by reactive molecular beam epitaxy (MBE) using Mn vapor and O2-seeded supersonic molecular beams (SMBs) both with and without radio frequency (RF) plasma excitation. For comparison, MnO(001) films were grown by reactive MBE using O2 from a leak valve. X-ray photoelectron spectroscopy confirmed the Mn2+ oxidation state and 10%–15% excess oxygen near the growth surface. Reflection high-energy electron diffraction and x-ray diffraction evidenced that the films were rock salt cubic MnO with very strong (001) orientation. High-angle annular dark field scanning transmission electron microscopy with energy-dispersive x-ray spectroscopy demonstrated abrupt MnO/MgO interfaces and indicated [(001)MnO||(001)MgO] epitaxial growth. Ex situ atomic force microscopy of films deposited without RF excitation revealed smooth growth surfaces. An SMB-grown MnO(001) film was converted to Mn3O4 with strong (110) orientation by post-growth exposure to an RF-discharge (RFD) SMB source providing O atoms; the surface of the resultant film contained elongated pits aligned with the MgO110 directions. In contrast, using the RFD-SMB source for growth resulted in MnO(001) films with elongated growth pits and square pyramidal hillocks aligned along the MgO110 and 100 directions, respectively.}, number={15}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Pedersen, Andrew J. and Liu, Junchen and Li, Fanxing and Lamb, H. Henry}, year={2024}, month={Apr} }
 @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{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{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{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={Chemical looping catalysis, enabled by redox-active mixed metal oxides, can produce a variety of value-added chemical products with higher efficiency and lower CO2 emissions.}, journal={CHEMICAL COMMUNICATIONS}, author={Liu, Junchen and Li, Fanxing}, year={2022}, month={Dec} }
 @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} }
 @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{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.}, 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{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={http://www.scopus.com/inward/record.url?eid=2-s2.0-85101732148&partnerID=MN8TOARS}, DOI={10.1038/s41467-021-21374-2}, abstractNote={Abstract}, 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{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{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{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} }