Phosphorus-doped h-boron nitride as an efficient metal-free catalyst for direct dehydrogenation of ethylbenzene

Direct dehydrogenation (DDH) of ethylbenzene to styrene catalyzed by metal-free materials is one of the most challenging topics in the chemical industry. We demonstrate that phosphorus-doped h-boron nitride (PBN) exhibits outstanding catalytic activity with a styrene production rate of 6.63 mmolST g−1 h−1 and a styrene selectivity of 95% even after 100 h in the DDH of ethylbenzene under steam-free conditions. The characterization and DFT calculations indicate that the N2PO and N3P–OH sites of PBN synergistically catalyze the reaction: the N2PO sites promote ethylbenzene C–H bond breaking, and the N3P–OH sites significantly lower the energy barrier of hydrogen associative desorption. The characterization of fresh and used catalysts indicates that the coverage of the N3P–OH sites by carbonaceous species is the main reason for the deactivation. This work facilitates the utilization of BN-based materials in the direct dehydrogenation of alkanes under steam-free reaction conditions.