Catalytic performance of Ti-SBA-15 prepared by chemical vapor deposition for propylene epoxidation: The effects of SBA-15 support and silylation

摘要

Ti-SBA-15 catalysts were prepared by the chemical vapor deposition (CVD) method using TiCl4 as titanium source and characterized by XRD, N2 desorption, FT-IR and UV-vis spectroscopies, and TG analysis. The effects of SBA-15 support and silylation on the catalytic performances of Ti-SBA-15 catalysts for the propylene epoxidation using cumene hydroperoxide (CHP) as the oxidant were investigated. The results show that SBA-15 supports prepared with different methods have different surface properties, leading to the difference on the amount and the status of Ti deposited on the SBA-15 surface and different catalytic performances. On the other hand, the silylated Ti-SBA-15 catalysts exhibit higher activities than the unsi-lylated Ti-SBA-15 catalyst due to the increase of the hydrophobicity of the catalyst, which originates from the impact of methyl groups anchored on the surface of Ti-SBA-15 catalysts. The silylated Ti-SBA-15 catalyst prepared with reflux for 6 h exhibits the best epoxidation performances, over which CHP conversion of 90.3% and PO selectivity to CHP of 96.2% can be obtained.