The Effect of N-Doping in Activated Carbon-Supported Au-Sr Catalysts for Acetylene Hydrochlorination to Vinyl Chloride

We used N-doped activated carbon (NAC) as support to prepare a novel Au-Sr catalyst and evaluated the effect of N-dopants on the performance of Au-Sr catalyst in acetylene hydrochlorination. A promoting effect was observed when N atoms were incorporated into AC framework, and the prepared SrAu/NAC catalyst demonstrated optimal activity compared with the undoped Au/AC and SrAu/AC catalysts. The SrAu/NAC also showed an excellent stability during the 500h test, with acetylene conversion and vinyl chloride selectivity both exceeding 99.9%. A detailed characterization was investigated through XPS, TPD, TPR, TGA, PXRD, TEM, AAS, and BET to reveal the physicochemical properties of the related catalysts. It is demonstrated that the NAC can function as an effective support to enhance activity and life of Au-based catalysts with unique electronic property, and the presence of doped nitrogen species as anchor sites is beneficial to increasing the electron density of active Au(III) center through electron transfer from doped N atoms to the active Au(III) species, and stabilizing active Au(III) ions and retarding its reduction within catalyst preparation and use process. Moreover, the combination of N-dopants and strontium additive may promote a synergistic effect to make active Au species disperse better and significantly enhance the adsorption of HCl, remarkably suppress the reduction of active cationic Au(III), and effectively inhibit carbon deposition in the catalytic reaction.