Aqua regia activated Au/C catalysts for the hydrochlorination of acetylene

Au/C catalysts are effective materials for the gas phase hydrochlorination of acetylene to vinyl chloride monomer, and to date, the most effective catalyst preparation protocol makes use of impregnation using aqua regia. In the present study, the effect of this solvent is evaluated and discussed in detail by modifying the ratio of HCl and HNO3 and the temperature of the impregnation step. These factors are observed to affect the Au3+/Au0 ratio of the final catalyst, in addition to the modification of the functional groups of the carbon used as support. The results can be rationalised by the oxidation effect of HNO3 on both the gold nanoparticles and the functional groups on the carbon surface, as well as a nucleation effect of HCl towards gold over the carbon support.