Enhancement of the activity and stability of Au/TS-1 catalyst in the gas-phase epoxidation of propene through alkali carbonate modification

Abstract

A serious of robust Au/TS-1 catalysts were prepared by modifying with various alkali carbonates including Na2CO3, K2CO3, Rb2CO3 and Cs2CO3via the ultrasonic impregnation. The alkali carbonate-modified Au/TS-1 catalysts were characterized by XRD, ICP, XPS, UV-vis, FT-IR, NH3-TPD and HAADF-STEM and their catalyticactivity and stability in the gas-phase epoxidation of propene were investigated in a fixed-bed reactor in the presence of H2 and O2. The results indicate that the modification with alkali carbonates can decrease the surface acidity and inhibit the aggregation of Au particles; moreover, Rb2CO3 and Cs2CO3can even reduce thecontent of extra-framework TiinRb-Au/TS-1 and Ce-Au/TS-1. Thecatalytic activity and stability of Au/TS-1 in the gas-phase epoxidation of propene are significantly improved after the modification with alkali carbonates. In particular, Cs2CO3-modified Cs-Au/TS-1 catalyst exhibits the best performance, witha propene conversion of 6.2%,selectivity of 86.2% to propene oxide (PO) and H2utilization efficiency of 26.2%. The results suggest that alkali carbonate modification could be a novel strategy to enhance the catalytic activity and stability of Au/TS-1 in propene epoxidation.