Graphitic Carbon Nitride Catalyzes Selective Oxidative Dehydrogenation of Propane

Abstract Exothermic oxidative dehydrogenation of propane (ODHP) to olefins is a promising alternative to industrialized direct dehydrogenation. However, it encounters a great challenge to control the olefin selectivity as the over-oxidation to produce carbon oxides (COx) is thermodynamically more favorable. In this work, graphitic carbon nitride was reported to be a new kind of metal-free catalyst for ODHP, obtaining high selectivity for propylene (74.7%) and ethylene (14.9%) at a given propane conversion of 12.8%. Based on the spectroscopic insights and in situ experiments, the carbonyl groups modified on the graphitic carbon nitride were affirmed as active sites. A feasible ODHP reaction pathway was hypothesized by density functional theory (DFT) in which two adjacent carbonyl groups on the edge of carbon nitride can activate two C-H bonds of propane simultaneously, thus avoiding the generation of free C3H7* radicals and leading to the high selectivity of light olefins.