Phosphine-oxide organic ligand improved Cu-based catalyst for acetylene hydrochlorination

Abstract Considering the disadvantages of Cu-based catalyst for acetylene hydrochlorination, such as poor dispersion, severe carbon deposition and insufficient active sites, supported Cu-complex catalysts were synthesized by using phosphine-oxide organic compounds as ligands. A local active domain was successfully constructed based on the complexation of Cu atom to heteroatomic structure in meticulously selected ligands, in which the phenyl group acts as an electron donor to change the CuCl2 active site electronic structure. The density functional theory calculation proved the existence of a strong interaction between triphenylphosphine oxide and CuCl2, and synchronously, electrons on the benzene ring were transferred to the Cl atom in CuCl2, stabilizing the Cu species. This superior activity may be attributed to the heightened adsorption of HCl and weakened C2H2 and vinyl chloride adsorption by the constructed local active domain, which impedes the carbon deposition that promotes the continuous exposure of active sites. Under the reaction conditions: T = 180 ℃, GHSVC2H2 = 180 h-1 and VHCl/VC2H2 = 1.2, the C2H2 conversion of 15%Cu7%TPPO/AC reaches 88%, which was over 30% higher than 15%Cu/AC catalyst. The significantly improved activity and stability of the proposed catalyst provides a reference for green and sustainable production of vinyl chloride.