Graphitic carbon nitride catalyzes selective oxidative dehydrogenation of propane

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.