Silylation Modification on Surface of Ti-MCM-41 Molecular Sieves

Titanium-containing mesoporous molecular sieve Ti-MCM-41 was synthesized by hydrothermal crystallization using tetraethyl orthosilicate(TEOS) as Si source, tetrabutylorthotitanate(TBOT) as Ti source and cationic surfactant CnTMABr as template. Serveral analytic methods including XRD, FT-IR, SEM and N2-absorption-desorption were used to characterize the structures of the synthesized Ti-MCM-41 molecular sieves. Effects of silylation methods on hydrophobicity and catalytic oxidation performance of Ti-MCM-41 molecular sieves were investigated as well. The results show that the chain length of template CnTMABr influences the ordered structures of Ti-MCM-41 molecular sieves. A long-ranged ordered structure of Ti-MCM-41 could be obtained only when n=16. Through different treatments of silylation, BET surface area, pore diameter and pore volume of Ti-MCM-41 are decreased, while Si/Ti, the hydrophobicity, catalytic oxidation performance of Ti-MCM-41 molecular sieves and the selectivity of epoxide are increased. Among the selected silylation agents, TMSCl(trimetnylsilyl chloride)shows the highest silylation efficiency.