Trimetallic Au‐Cu‐K/AC for acetylene hydrochlorination

Abstract The metal chloride of KCl was chosen to modify Au‐Cu/AC to decrease the noble metal of gold and enhance the catalytic performance. Then a mercury‐free catalyst of Au‐Cu‐K/AC was prepared by the impregnation method. The catalytic performances of mercury‐free catalyst for acetylene hydrochlorination were conducted for 1600 h in a fixed bed reactor by a single‐tube pilot unit. The fresh and used catalysts were also characterized in comparison. The results showed that the acetylene conversion on mercury‐free catalyst decreased slowly from 98 % to 89 %, and the vinyl chloride monomer (VCM) selectivity was kept at 99.7 % under reaction conditions of temperature 165 °C, gas hourly space velocity (GHSV) 40 h −1 , and feed volume ratio of HCl to C 2 H 2 of 1.05 during 1600 h on stream. The results showed that the additives of K with Cu can make the active species of gold dispersed well and retard the aggregation of particles. The reason for the slow decline of acetylene conversion for Au‐Cu‐K/AC catalyst was the whisker carbon deposition, shown in a faint yellow colour over the catalyst surface, which consisted of short‐chain hydrocarbon molecules. Further study for accelerated deactivation of sole metal in the catalyst gives the clues that the non‐noble metal of Cu in Au‐Cu‐K/AC catalyst plays a key role to form the deposition.