Abstract: Ti/HMS samples were prepared by hydrothermal synthesis (HTS) and chemical vapor deposition (CVD) methods and then silylated by trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDSZ) in a vapor phase. The samples were characterized by XRD, N2 adsorption, FT-IR,29SiNMR, and DRUV-Vis, and their catalytic performance for the epoxidation of propylene using cumene hydroperoxide as oxidant was measured. The silylation could promote remarkably the catalytic performance. The Ti/HMS silylated by HMDSZ had much higher catalytic activity than that silylated by TMCS. This is because TMCS could not only react with silanol but also breakSi-O-TiandSi-O-Sibonds to form new silanol, which led to higher hydrophilicity for the silylated samples than those silylated by HMDSZ. The silylation with TMCS partially destroyed the tetracoordinated framework titanium species in Ti/HMS, but this did not occur in the silylation with HMDSZ.

Key words: titanium, HMS molecular sieve, hydrothermal synthesis, chemical vapor deposition, silylation, propylene, epoxidation