Single-Atom Au^I-N₃ Site for Acetylene Hydrochlorination Reaction

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 AuCl₃ is inclined to be reduced by acetylene and lose its activity during the reaction process. Here, we presented the construction of Au^I-N₃ active sites through single gold atom dispersed on g-C₃N₄ (Au₁/g-C₃N₄), 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-N₃ sites tend to coordinate with HCl than C₂H₂ in the initial reaction. The Au^I-N₃ sites cannot be reduced into Au⁰ 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.