Probing the reaction mechanism of acetylene hydrochlorination on metal-free doped boron nitride: Decisive role of carbon dopant

As emerging as highly active metal-free acetylene hydrochlorination catalyst, recently boron nitride attracted great attentions from both experimental and computational explorations. In this work, the carbon doping is verified to be indispensable to trigger the activities of pristine h-BN catalyst from first principles calculations. The effects on electronic structure of h-BN induced by carbon doping are examined from ELF, PDOS, and charge analysis which have direct impacts on the catalytic capabilities. The pathways can be categorized to be either C2H2 or HCl adsorption as first step. Although these two categories have distinct limiting step and mechanism, the shared feature is that the activation of C2H2 is key to the vinyl chloride formation. Furthermore, TOFs of different pathways are calculated to determine the most favorable catalytic route and is in a qualitatively agreement with largest barrier of elementary step. The importance of HCl-starting pathway is revealed from the comparison of TOF which is severely underestimated previously. In the end, the deep reactions which might be leading to precursor of cokes are explored and shed lights on the origin of superior stability of catalyst.