Effects of preparation method and precipitator on the propylene epoxidation over Ag/TS-1 in the gas phase

The effects of preparation method and precipitator on the catalytic properties of Ag/TS-1 in the gas-phase epoxidation of propylene were investigated in a fixed bed, quartz reactor. The Ag/TS-1 catalysts were characterized by XRD, UV–vis, FT-IR and TEM. The results show that the catalysts prepared by both deposition-precipitation (DP) and impregnation (IMP) methods exhibit catalytic activity and selectivity in the reaction. 0.48% propylene conversion with 57.88% selectivity to PO is obtained over Ag/TS-1 catalyst prepared by IMP method. However, DP method is optimum. Alkaline metal carbonate is a suitable precipitator. Using K2CO3 as the precipitator, the catalyst exhibits high activity and selectivity; using Cs2CO3 as the precipitator, the stability of the catalyst is improved; the propylene conversion and the selectivity to PO are 1.28% and 84.12%, 1.11% and 85.41% at 31 and 54 min, respectively. Besides the dispersion of silver particles, pH value of precipitators as well as the interaction between silver species and the support are the key factors for the gas-phase epoxidation of propylene.