Effect of Oxide Support on Catalytic Performance of FeNi-based Catalysts for CO2-assisted Oxidative Dehydrogenation of Ethane

CO2-assisted oxidative dehydrogenation of ethane over Fe3Ni1 catalysts supported on SiO2, ZrO2, and CeO2, as well as CeO2-supported Fe3xNix with different metal loadings (x=0.25, 0.5, 1, 2, 4), were investigated to illustrate the effects of the oxide support and the metal loading amount in tuning the catalytic activity and selectivity. The oxidation state and the dispersion of the Ni and Fe species on the supported catalysts were determined by using in-situ X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) measurements. Among these FeNi-based catalysts, Fe3Ni1/CeO2 exhibited the best catalytic activity and maximum ethylene yield for the oxidative dehydrogenation of ethane. Excessive loading amount of active metals changed the reaction selectivity from oxidative dehydrogenation to dry reforming. The high activity and selectivity for CO2-assisted oxidative dehydrogenation of ethane over Fe3Ni1/CeO2 are likely due to the formation of Ni-FeOx/CeOx interfacial sites, while the presence of Ni-ZrO2 interfacial sites on Fe3Ni1/ZrO2 and NiFe-CeOx interfacial sites on Fe12Ni4/CeO2 likely tune the reaction selectivity toward dry reforming of ethane.