Epoxide Rearrangement. VIII. The Acidic and Basic Properties of TiO2–SiO2–MgO and Its Catalytic Activities

Abstract

Abstract Four kinds of TiO2–SiO2–MgO having different molar ratios, TiO2–SiO2–MgO (1 : 1 : 1, 10 : 10 : 1, 1 : 10 : 10, and 10 : 1 : 10), were prepared, their acidic and basic properties being examined by titration with butylamine and benzoic acid in benzene, respectively. The acidity of TiO2–SiO2–MgO was attributed to that of TiO2–SiO2 and SiO2–MgO. The amount of strong acid sites of H0≤–5.6 decreased with the addition of MgO to TiO2–SiO2. The basicity of TiO2–SiO2–MgO was attributed to that of TiO2–MgO and decreased with the increase in SiO2 content. Catalytic activities for the isomerization of 1-butene and the decomposition of 4-hydroxy-4-methyl-2-pentanone are correlated with the acidity and basicity, respectively. For isomerization of 1-methylcyclohexene oxide and d-limonene oxide, TiO2–SiO2–MgO and TiO2–SiO2 showed high activities for the preferential formation of ketones except TiO2–SiO2–MgO (10: 1: 10) over which allyl alcohols were produced preferentially. The selectivities for the isomerization of two epoxides were interpreted in terms of the acidic and basic properties of the catalysts.