@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{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} }
 @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{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={http://www.scopus.com/inward/record.url?eid=2-s2.0-85067840834&partnerID=MN8TOARS}, 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{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} }
 @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={https://doi.org/10.1021/acs.chemmater.8b04349}, 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{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://dx.doi.org/10.1016/j.apcatb.2018.03.037}, 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{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{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} }