The gold-catalyzed acetylene hydrochlorination reaction is an important process to produce vinyl chloride monomer in the polyvinyl chloride industry. The traditional catalyst of carbon-supported AuCl 3 is inclined to be reduced by acetylene and lose its activity during the reaction process. Here, we presented the construction of Au I −N 3 active sites through single gold atom dispersed on g-C 3 N 4 (Au 1 /g-C 3 N 4 ), which shows robust catalytic performance toward acetylene hydrochlorination. The Au species is shown to have Au I oxidation state, and it is coordinated with three nitrogen atoms of tri-s-triazine repeating units, which is consistent with density functional theory (DFT) modeling and XAFS measurements. Through DFT study, we demonstrate that the Au I −N 3 sites tend to coordinate with HCl than C 2 H 2 in the initial reaction. The Au I −N 3 sites cannot be reduced into Au 0 oxidation state easily and thus maintain their activity as stable catalytic active sites. The single-atom-site Au catalyst with nitrogen coordination environment and corresponding electronic state provides an efficient pathway for acetylene hydrochlorination reaction.

Acetylene hydrochlorination is a major industrial technology for manufacturing vinyl chloride monomer in regions with abundant coal resources; however, it is plagued by the use of mercury(II) chloride catalyst. The development of a nonmercury catalyst has been extensively explored. Herein, we report a N-doped carbon catalyst derived from ZIF-8 with both high activity and quite good stability. The acetylene conversion reached 92% and decreased slightly during a 200 h test at 220 °C and atmospheric pressure. Experimental studies and theoretical calculations indicate that C atoms adjacent to the pyridinic N are the active sites, and coke deposition covering pyridinic N is the main reason for catalyst deactivation. The performance of those N-doped carbons makes it possible for practical applications with further effort. Furthermore, the result also provides guidance for designing metal-free catalysts for similar reactions.

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