Synthesis, Characterization, and Catalytic Properties of Tungsten-containing Mesoporous Materials

摘要

Tungsten oxides are versatile catalytic components that have been extensively applied to catalyze hydrodesulfurization, alkene metathesis, and hydroxylation of unsaturated organic compounds. Zhang et al [1] and Bregeault et al [2] synthesized tungsten containing MCM-41 using ammonium tungstate or W(Ⅵ)oxoperoxo species by direct hydrothermal method and tested their materials in hydroxylation of cyclohexene and epoxidation of cyclooctene, respectively. Works on tungsten oxide supported on mesoporous material are very limited, and several important questions regarding the influence of the nature of silica support, catalyst preparation methods, and liquid phase reaction medium on catalytic properties remained to be answered. In this contribution, we prepared a series of tungsten containing mesoporous silica W-MCM-41 and W-SBA-15 both by direct hydrothermal (H) and post-synthetic grafting (G) methods; designated by W-MCM-41(H), W-MCM-41 (G), W-SBA-15(H), and W-SBA-15(G), respectively. After physicochemical properties of the catalysts prepared were evaluated, their catalytic activities in oxidation of 2,6-di-tert-butyl phenol (2,6DTBP) with H_2O_2 in acetone and acetic acid were compared. The effect of solvent was more thoroughly investigated in the epoxidation of cis-cyclooctene, and possible pathways for the reaction mechanism was proposed.