@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{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{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_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{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{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{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} }