Tri‐Coordinated Boron Species in Confined Boron Oxide Catalysts for Enhanced Low‐Temperature Oxidative Dehydrogenation of Propane

Abstract

Abstract Boron‐based catalysts exhibit great potential for oxidative dehydrogenation of propane (ODHP) to produce olefins. The straightforward synthesis of confined boron‐based catalysts commonly using H 3 BO 3 is intractable because of its abundant hydroxyl groups easily interacting with the supports in a spatially nonselective manner. Herein, we managed to construct a confined BO x @SiO 2 catalyst showing an impressive low‐temperature (400 °C) activity. This catalyst was prepared via the encapsulation of BN nanosheets by SiO 2 shell and subsequent oxidization steps. The in situ generated boron–oxygen species were anchored to silica shells via B─O─Si and hydrogen bonds. BO x @SiO 2 exhibited a unique catalytic behavior of propane conversion uprush, increasing from 5.3% at 410 °C to 28.4% at 424.6 °C for ODHP reaction. That was attributed to the efficient activation of propane triggered by the newly formed tri‐coordinated B─OH (B[3] a and B[3] b ) active sites from the dispersion of molten BO x species in confined SiO 2 . Ab initio molecular dynamics (AIMD) simulations revealed that in the confined structure, the bond angles of O─B─O and B─O─B and system disorder of BO x species increased significantly in molten state, favoring the dispersion of BO x species and formation of B─OH groups, which drove the uprush of propane conversion.