Abstract
The effect of reduction temperature on the structure of mesoporous Ni-Fe-Al2O3 catalysts and their catalytic activity for the oxidative dehydrogenation of ethane (ODH) have been investigated. Low reduction temperature at 400 degrees C leads to the reduction of Fe3+-based oxides to lower valence FeOx species, but nickel ions in the [-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 degrees 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 contribute to the selective conversion of ethane to ethylene.