Effect of pre-reduction on the performance of Fe2O3/Al2O3 catalysts in dehydrogenation of propane

Abstract

The effect of carbon monoxide and hydrogen pre-reduction on the performance of 10FeAl catalyst in propane dehydrogenation was studied. The optimal results, 20wt% propylene yield at an overall propane conversion of 24wt% was obtained over the sample pre-reduced by hydrogen at 600°C for 10h at 560°C. Based on XRD, XPS and IR results, it is proposed that the carbon and FexC species formed from propylene cracking under the activation of surface adsorbed oxygen species are the active sites for the formation of abundant methane over untreated 10FeAl catalyst. Pre-reduction treatment leads to the consumption of surface adsorbed oxygen species and the formation of Fe and Fe2+ species, which are active for propane dehydrogenation. For one thing, propane hydrogenolysis is strongly inhibited due to the large size (around 30nm) of Fe grains. For another, propylene cracking and the generation of carbon and FexC species are largely suppressed in the absence of surface electronegative oxygen species, hence inhibiting propane cracking and hydrogenolysis reactions, resulting in greatly improved dehydrogenation performance.