Three-Dimensional Porous Hexagonal Boron Nitride Fibers as Metal-Free Catalysts with Enhanced Catalytic Activity for Oxidative Dehydrogenation of Propane

Boron nitride (BN) as an emerging and revolutionary metal-free catalyst has demonstrated great potential in various oxidative dehydrogenation reactions. However, traditional BN sheets always present low catalytic performance because of the lack of exposed surface-active sites. In this work, we synthesized a three-dimensional (3D) porous fiber-like BN material via self-assembly of boric acid and melamine. In the catalytic oxidative dehydrogenation of propane (ODHP), the as-synthesized BN showed remarkable selectivity to propylene (76.4%), and the selectivity to alkenes was above 90% at a 16.4% conversion of propane, while the selectivity to undesired CO2 was negligible. Meanwhile, the 3D BN also exhibited excellent catalytic stability up to 200 h at 520 °C, which was much better than traditional BN sheets. Mechanistic insight into the formation process of 3D porous BN fibers suggests the key role of surface BOX affiliated to BN for stable 3D structure in contributing to the high catalytic activity and outstanding stability. This work is, therefore, a blueprint for the construction of the next-generation BN catalyst for a highly efficient ODHP.