Understanding the origin for propane non-oxidative dehydrogenation catalysed by d2-d8 transition metals

Abstract

Non-oxidative dehydrogenation of propane is a potential route to produce more valuable chemical feedstock propene. Understanding of the catalytic origin is essential for high performance catalysts design. Herein, the detailed mechanisms for non-oxidative dehydrogenation of propane catalysed by silica supported vanadium are systematically studied to elucidate a possible reaction network, in which the stepwise dissociative C-H bond activation is consistently most favourable. Consequently, stepwise dissociative C-H bond activation is used to investigate the d2–d8 transition metal-catalysed non-oxidative dehydrogenation of propane. Frontier orbital analysis reveals that non-oxidative dehydrogenation of propane originates from the interaction between the highest occupied molecular orbital (HOMO) of propane and the lowest unoccupied molecular orbital (LUMO) of the catalysts, indicating that the smaller the gap between the HOMO and LUMO, the higher the reaction activity. Moreover, the largest energy barriers for these reactions correlate with the LUMOcatalyst–HOMOpropane gap. A lower LUMOcatalyst–HOMOpropane gap leads to a lower reaction barrier and higher activity of the catalyst. This study provides a new strategy of theoretical catalyst design for non-oxidative propane dehydrogenation by modulating the gap between the HOMO of propane and the LUMO of catalysts.