O2 Activation and Oxidative Dehydrogenation of Propane on Hexagonal Boron Nitride: Mechanism Revisited

Since the first report of the application of hexagonal boron nitride (h-BN) in oxidative dehydrogenation of propane (ODHP), numerous efforts have been devoted to the exploration of the catalytic mechanism for the rational design of highly active catalysts. The present work focuses on the mechanism of O-2 activation and oxidative dehydrogenation of propane (ODHP) on h-BN by using the density functional theory (DFT). The armchair, boron-atom-terminated zigzag (zig-B), and nitride-atom-terminated zigzag (zig-N) edges were selected as the hypothetical active sites. Computational results show that the dissociative adsorption of O-2 is more favorable than the molecular adsorption at all selected sites. For the mechanism of ODHP, our DFT results show that the zig-B edge is the most active site based on kinetic and thermodynamic analysis. In addition, a possible competitive reaction model (C-C bond break vs dehydrogenation) on the high selectivity to propene has been proposed. We propose that h-BN material with rich zig-B edges can enhance the ODHP activity based on the current results. Last, quantum analysis methods, such as electron density difference, charge distributions, and frontier orbitals have also been used to interpret the chemical nature of ODHP reaction.