Process monitoring of the Au-S bond conversion in acetylene hydrochlorination

Abstract The continuous expansion of vinyl chloride production increases environmental pollution caused by mercury catalysts, which is an issue that urgently needs to be solved. Green and stable catalysts should be researched to alleviate this issue. In this research, Thiolactic acid acts as a ligand where sulfhydryl groups form a stable complex with Au on the surface of a spherical activated carbon (SAC). An Au-Thiolactic acid/SAC catalyst was designed with a Au theoretical loading of 0.5%(mass) to overcome the disadvantages of traditional Au-based catalysts, such as a low conversion rate and poor life cycle. The ratio of Au to ligand was screened, and the activity was best when Au/S = 1:8. The formation of the Au-S bond was proven by FT-IR and UV-vis. The longevity test of the Au1S8 /SAC catalyst was carried out at 1200 h-1 for 50 h. Samples with reaction times of 0 h, 5 h, 10 h, 20 h, and 50 h were taken to monitor the catalyst status. The XPS and TPR tests proved that the Au-S bond broke as the acetylene hydrochlorination reaction proceeded. The DFT calculation proved that the Au-S bond is the active site, and the sulfur atom promotes the adsorption of C2H2 by the catalyst.