Metal–organic framework-derived cobalt and nitrogen co-doped porous carbon with four-coordinated Co–Nx for efficient acetylene hydrochlorination

Industrial production of vinyl chloride through acetylene hydrochlorination is a dominating technique in coal-rich areas, but its development is severely restricted by the use of toxic mercury chloride (HgCl 2 ) catalyst. Inspired by the fact that doped carbon materials active in acetylene hydrochlorination often have good performance in the oxygen reduction reaction, a series of cobalt and nitrogen co-doped porous carbon catalysts prepared by pyrolysis of bimetallic ZIFs based on ZIF-8 and ZIF-67 under N 2 were applied in acetylene hydrochlorination. The catalytic activities of the co-doped catalysts varied with Co addition, and the highest acetylene conversion could be up to 83% with a space velocity of 2.6 ml g −1 min −1 at 220°C when a small amount of cobalt was introduced. Results of several characterizations confirmed the existence of Co–N x in the co-doped carbons, pointing out that this coordination structure makes the catalysts have better ability to adsorb and activate C 2 H 2 . Density functional theory calculation finally proved that C atom adjacent to the N atom in Co–N 4 structure is the primary active site in co-doped catalysts with high activity. We also conclude that the decreased N content caused by Co 2 N decomposition and the coordination structure change of Co–N x should be responsible for the gradually worsening performances of the carbon catalysts with further Co addition. Our study provides a new route for improving the performance of N-doped carbon material in acetylene hydrochlorination and thus enhances its potential for practical application.