Understanding the origin of selective oxidative dehydrogenation of propane on boron-based catalysts

[Display omitted] •The supported B2O3/SiO2 catalysts show superior olefin selectivity in ODHP.•The surface oxidized boron species are the possible active sites for ODHP.•The >B--O-O--B< complex can act as a moderate oxidant to preferentially activate propane.•The suppressed adsorption of olefins are the keys in achieving high olefin selectivity. Boron-based catalysts have been reported to exhibit high selectivity to olefins in oxidative dehydrogenation of propane (ODHP). However, the origin of their superior ODHP selectivity to conventional vanadium-based catalysts is still under debate. In this work, we proposed that oxidized boron species is the active site for highly selective olefin formation in ODHP on boron-based catalysts. Combined isotopic and kinetic experiments suggested that O2 weakly bonds to the electron-deficient B center to form non-dissociative >B--O-O--B< on catalyst surface, which directly reacts with propane from the gas phase as a moderate oxidant in ODHP. The high selectivity of olefins in ODHP on such boron-based catalysts is due to the suppressed adsorption of olefins on>B--O-O--B< sites. These findings offer in-depth knowledge of ODHP on boron-based catalysts.