Dual-ligand engineering over Au-based catalyst for efficient acetylene hydrochlorination

Introducing ligand into the surface of gold (Au)-based catalyst has been recognized as an efficient strategy to enhance the performance of catalyst in acetylene hydrochlorination reaction. However, due to the multifactorial deactivation, the usage of single type of ligand has limitations on the performance improvement. In this work, two types of ligands including a molecular 2-methylimidazole and an ionic cetrimonium are selected to protect Aun+ species. After kinetics analysis, advanced characterization, and density functional theory simulation, we demonstrate the optimal interaction model between two ligands and Au species: Two 2-methylimidazole molecules are coordinated with high-valent Au species while cetrimonium is interacted via electrostatic interaction. Except the synergistic effect in the decrease of Au species reduction and agglomeration, the existence of molecular ligand greatly increases the adsorption of hydrogen chloride while the ionic ligand significantly inhibits the deposition of coke. Due to the positive effect of dual-ligands, we achieved 97.1% of acetylene conversion and 0.29 h−1 of deactivation rate under high gas hourly space velocity of acetylene. This work establishes a foundation to explore the property-activity relationships in Au-based catalyst via ligand engineering.