Gold–glutathione complex catalysts with carbon support for non-mercury catalytic acetylene hydrochlorination

Abstract

Gold–glutathione complex catalysts for acetylene hydrochlorination were prepared at different pH values. Coal-based columnar carbon, HAuCl₄·4H₂O and glutathione (GSH) were added as the carrier, the precursor and the protective/reductive agent, respectively. The catalysts were characterized by Fourier transform infrared spectroscopy, ultraviolet spectrum, N₂ adsorption/desorption, thermogravimetric analysis, temperature-programmed reduction/desorption, powder X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The highest activity is obtained over the Au1–GSH3/AC (pH 8.3) catalyst with the acetylene conversion of 82%, under the conditions of 170 °C and the C₂H₂ gas hourly space velocity (GHSV) of 360 h⁻¹. It is indicated that the addition of GSH can result in the reduction of Au³⁺ to Au⁺ during the catalysts preparation process, the species of Au⁺ and Au⁰ coexist in the fresh Au1–GSH3/AC catalysts, with the individual content close to 50%. Compared with fresh Au/AC catalyst comprised of Au³⁺ and Au⁰, it is illustrated that the presence of Au⁺ plays an important role in enhancing the catalytic activity. Adjusting the pH of the catalyst to a suitable value can make more active species disperse well on the catalysts, inhibit coke deposition and enhance the adsorption ability of reactants.