Study on Characterization and Catalytic Performance for Propylene Epoxidation of Ti/HMS Catalyst Prepared by Grafting Technology

Si-HMS mesoporous material was hydrothermally synthesized with tetraethyl orthosilicate as Si source, 1-hexadecylamine as template, ethanol and water as solvent. Ti speices were incorporated into the framework of Si-HMS with TiCl4 as Ti source by vapor-phase grafting technology; In order to improve the hydrophobicity of Ti/HMS, methyl was grafted on the surface of Ti/HMS with Hexamethyl disilazane as methyl-silicon group agent by liquid-phase technology. The structure, surface chemical component and hydrophobic properties of Ti/HMS catalyst were characterized by XRD, N2 adsorption, TEM, UV-Vis and FT-IR, etc.; The performance of catalytic epoxidation of propylene by Ti/HMS was studied in a slurry bed reactor and a fixed-bed reactor using cumene hydroperoxide as oxidant, respectively. The results showed that the prepared Ti/HMS catalysts possessed a typical mesporous structure, and Ti species existed as the tetra-coordinated form in the framework; the hydrophobicity of Ti/HMS was obviously improved after it was treated with silane. The Ti/HMS catalyst treated by silane has excellent activity, selectivity and stability. In the period of 2400 hs performance test, the CHP conversion was over 99.0%, the selectivity to PO was over 97.0%.