Effect of reduction temperature on structure and catalytic performance of mesoporous Ni-Fe-Al2O3 in oxidative dehydrogenation of ethane
The effect of reduction temperature on the structure of mesoporous Ni-Fe-Al2O3 catalysts and their catalytic activity for oxidative dehydrogenation of ethane (ODH) are investigated. Low reduction temperature at 400 oC leads to the reduction of Fe3+-based oxide to lower valance FeOx species, but nickel ion in [-Ni-O-Al-] framework cannot be reduced at this temperature. These highly dispersed Ni2+-based oxide and FeOx species with close proximity contribute to ethane dehydrogenation and N2O decomposition, respectively. When the reduction temperature is increased to 600 °C, a continuous reduction and migration of Ni2+ from the bulk phase to the surface took place, forming 5-6 nm isolated metallic Ni nanoparticles which resulted in a decrease in catalyst activity under this condition. Thus highly dispersed Ni2+-based oxide and FeOx species with close proximity effectively contributes to selective conversion of ethane to ethylene.