Activated carbon supported ternary gold–cesium(i)–indium(iii) catalyst for the hydrochlorination of acetylene

Abstract

Commercialization of acetylene hydrochlorination using AuCl₃ catalysts has been impeded by its poor stability. We have been studying CsCl as a promoter, which can improve acetylene hydrochlorination activity and has resistance to catalytic deactivation. In^III added to the Au–Cs^I/AC catalysts worked as efficient catalysts for the hydrochlorination of acetylene to vinyl chloride. A series of trimetallic catalysts (1AuxIn^III4Cs^I/AC with x = 0.5, 1, 2, 3) were prepared and assessed for their ability to promote hydrochlorination of acetylene. The enhancement of stability observed for a Au/In^III/Cs^I weight ratio of 1 : 1 : 4 was particularly remarkable. It delivered stable performance within the conversion of acetylene, reaching more than 92.8%, and there was only 3.7% C₂H₂ conversion loss after running for 50 h under the reaction conditions of a temperature of 180 °C and a C₂H₂ hourly space velocity of 1480 h⁻¹. Moreover, the 1Au1In^III4Cs^I/AC catalyst delivered stable performance with an estimated lifetime exceeding 6520 h at a C₂H₂ hourly space velocity of 50 h⁻¹. H₂-TPR, TEM, HCl-TPD, C₂H₂-TPD, XPS and TGA techniques were further applied to reveal the structural information on the Au–In^III–Cs^I/AC catalysts. The results reveal that the addition of InCl₃ increased the electron density of Au³⁺ species via electron transfer from the In atoms to the Au³⁺ center which can increase the adsorption of hydrogen chloride and therefore improve the catalytic stability. These results demonstrate that the addition of metal additives CsCl and InCl₃ results in a synergistic effect to enhance the activity and the stability of Au-based catalysts. The excellent catalytic performance of the 1Au1In^III4Cs^I/AC catalyst demonstrated its potential as an alternative to mercury chloride catalysts for acetylene hydrochlorination.