Revealing the origin of the reactivity of metal-free boron nitride catalysts in oxidative dehydrogenation of propane

摘要

Oxidative dehydrogenation (ODH) of propane is one of effective catalytic routes to produce value-added propene. Recently, boron nitride catalysts demonstrate extraordinary catalytic performance in ODH of propane with over 90% selectivity under 14% propane conversion. In this work, first principles calculations were performed to unravel the origin of activity of boron nitride catalyst. Three most active centers, including boron zigzag edge, nitrogen vacancies, and O = group, are identified from the screening propane first C-H bond activation among a large pool of candidates. The calculations verified the intrinsic reactivity of boron nitride which mostly comes from boron atoms at defective sites. The strong bonding between boron and carbon in propane dissociated fragments is accountable for the observed intrinsic reactivity. The detailed reaction pathway is revealed which cover from propene formation to active site regeneration. It is found that more critical step on pathway is regeneration rather than C-H bond activation. On the other hand, the active site could undergo conversion between each other at regeneration step. Furthermore, the deep dehydrogenation of propene is obstructed at the active site which uncovers the origin of high selectivity. Overall, current work gives a comprehensive description of catalytic properties of born nitride catalyst.