Nitrogen-doped carbon supports with terminated hydrogen and their effects on active gold species: a density functional study

Abstract

In order to disclose the reason that the N-doped carbon support can enhance the stability of Au-based catalysts for acetylene hydrochlorination, we established a big graphene cluster model of C₁₁₀H₂₈ to investigate the effect of different nitrogen-doped carbon supports on three kinds of gold species models of Au dimers, Au₂Cl₂ and Au₂Cl₆, through DFT calculations. Comparing the adsorption energy of each Au complex and the transferred charge from the support to the Au complex, it is observed that on the N-doped support GRN-I (the pyridinic N-doped graphene) the adsorption energies of the Au dimer, Au₂Cl₂ and Au₂Cl₆, are much higher than those on other three kinds of supports, and the Au complex accepts most of the transferred charges from the support of GRN-I. The effect of different supports on the adsorption of C₂H₂ and HCl was studied on Au₂Cl₆/supports, suggesting that the co-adsorption of both reactants occurs on Au₂Cl₆/GRN-I. The results indicate that the N-doped support of GRN-I can stabilize the gold species Au₂Cl₆ and enhance the interaction between Au₂Cl₆ and HCl, which can inhibit the reduction of Au³⁺ and then increase the long-term stability of Au-based catalysts.