Hydrothermal synthesis of tin containing mesoporous silicas and their catalytic performance over Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone: comparison of Sn/MCM-41 and Sn/SBA-15

In this work, a series of tin containing mesoporous silicas (Sn/MCM-41 and Sn/SBA-15) were prepared by a one-pot hydrothermal method and their physical and chemical properties were characterized by various techniques such as powder X-ray diffraction, nitrogen adsorption-desorption and transmission electron microscopy. Among these catalysts, Sn/SBA-15(50) exhibited the highest catalytic activity for Baeyer-Villiger oxidation of cyclohexanone to epsilon-crolactone using hydrogen peroxide (H2O2) as the green oxidant. The best methodology was to carry out the reaction in 1,4-dioxane under 10 wt% Sn/SBA-15 catalyst of 0.1 mol cyclohexanone at 70 A degrees C for 4 h, and a molar ratio cyclohexanone: oxidant of 1:3. Furthermore, this heterogeneous mesoporous Sn/SBA-15 catalyst was reusable without any appreciable loss in activity and selectivity after three cycles.