Pyrrolidone ligand improved Cu-based catalysts with high performance for acetylene hydrochlorination

A series of Cu-pyrrolidone/spherical activated carbon (SAC) catalysts were prepared via a simple incipient wetness impregnation method and then assessed in acetylene hydrochlorination, and the catalytic evaluation result indicated that the 1-methyl-2-pyrrolidinone (NMP) ligand was found to be the most effective one to significantly improve the activity and stability of Cu catalyst. The catalyst with the optimal molar ratio of NMP/Cu = 0.25 showed 94.2% acetylene conversion at 180°C and an acetylene gas hourly space velocity of 180 h −1 . Moreover, the acetylene conversion of Cu-0.25NMP/SAC remained stable over 99.1% for about 220 h under the industrial condition. Transmission electron microscopy (TEM) analyses proved that NMP ligand improved the dispersion of Cu species. In addition, hydrogen temperature-programmed reduction (H 2 -TPR), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), and Brunner–Emmet–Teller (BET) indicated that the additive of NMP was preferential to stabilize the catalytic active Cu + and Cu 2+ species and inhibit the reduction of Cu α+ to Cu 0 during the preparation process and reaction, hence restraining the coke deposition. Furthermore, the steady coordination structure between Cu and NMP was confirmed by Fourier-transform infrared spectra (FT-IR) and Raman combining with density functional theory (DFT) calculation, which could effectively lower the adsorption energy of catalyst for C 2 H 2 and inhibit the serious carbon deposition caused by excessive acetylene self-accumulation. Our findings suggest that the efficient, well-stabilized cost-effective, and environmentally friendly Cu catalyst has great potential in acetylene hydrochlorination.