TiO2–SiO2 mixed oxides: Xerogel catalyst for the Selective Epoxidation of cyclohexene

摘要

ABSTRACT A porous TiO2–SiO2 mixed metal oxide was synthesized via sol–gel route using inorganic precursors and subsequently dried, and then calcined at different temperatures (250, 400 and 600 °C). The mixed oxide was characterized by XRD, as well as by FTIR and diffuse reflectance ultraviolet–visible (DRS-UV–vis). The hydrophobicity (H) and relative abundance of Ti–O–Si linkages or Ti dispersion (D, T) were calculated. The catalysts were evaluated in the cyclohexene epoxidation with TBHP (tertbutyl hydroperoxide) as oxidant agent; the selectivity toward cyclohexene epoxide was 100 % and the conversion was 44 %. The effects of varying the catalyst calcination temperature and adding slowly the oxidant and solvent were investigated. The catalytic data obtained showed that the activity can be influenced by the coordination environment of titanium species. The insights obtained from these studies allowed a fundamental understanding of the relationships between the structural characteristics and the physicochemical/reactivity properties of titania-silica catalysts. .