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 degrees 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(alpha+)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.

Automated summary

By adding 1-methyl-2-pyrrolidinone (NMP) ligand, the activity and stability of the Cu-pyrrolidone/spherical activated carbon catalysts were significantly improved. The optimal molar ratio of NMP/Cu = 0.25 showed the best performance with a 94.2% acetylene conversion rate. NMP enhanced the dispersion of Cu species, stabilized Cu(+) and Cu(2+) species, and inhibited coke deposition, demonstrating great potential in acetylene hydrochlorination.