Synthesis of highly accessible gallosilicates via impregnation procedure: enhanced catalytic performances in the conversion of glycerol into solketal

Two mesoporous gallosilicates with extra-small particle size were synthesized via wet impregnation starting from lactate or citrate-type Ga(III) precursors. The structural and textural properties of the materials were extensively characterized by different techniques. Both materials consist of nanosized particles and display a remarkably high surface area and a pore size distribution typical of mesoporous MCM-41-like materials. The two solids were tested as catalysts in acetalization of glycerol with acetone to produce solketal (2,2-dimethyl-1,3-dioxolane-4-methanol). Both catalysts displayed excellent performances and achieved higher turnover numbers compared to other Ga-silicates reported in literature. The outstanding activity of these catalysts is attributed to the combination of acidity, large specific surface area as well as to the full accessibility of the active sites as consequence of the impregnation procedure. The best catalysts are truly heterogeneous with absence of Ga leaching and reusable in successive catalytic cycles after thermal treatment without significant deterioration of the catalytic performance.