Ti-MCM-41 silylation:: Development of a simple methodology for its estimation -: Silylation effect on the activity and selectivity in the limonene oxidation with H2O2

Ti-MCM-41 was prepared and characterized. The isomorphical substitution of Si4+ by Ti4+ and the presence of mesoporous hexagonal structure were verified. The solid was silylated with increasing quantities of hexamethyldisilazane. This process did not change the structural properties of the solid. Using themogravimetric analysis, the optimal quantity of the silylant agent to neutralize the superficial silanols was evaluated. The non-silylated and the silylated solids (with the optimal quantity) were tested in the limonene oxidation with hydrogen peroxide. The silylated solid showed a greater hydrogen peroxide efficiency and a higher activity and selectivity in the limonene epoxidation, compared with the non-silylated one. These effects are attributed to the higher hydrophobic character of the solid surface, produced by the silanols neutralization. (c) 2005 Elsevier B.V. All rights reserved.