Highly-efficient conversion of glycerol to solketal over heterogeneous Lewis acid catalysts

The acetalization of acetone with glycerol to yield 2,2-dimethyl-1,3-dioxolane-4-methanol (solketal) was successfully catalyzed by mesoporous substituted silicates including the novel Hf-TUD-1 material. This reaction offers an attractive path for the conversion of glycerol, which is the main side-product in the synthesis of biodiesel, to a valuable compound with potential for industrial applications. The most promising among the heterogeneous catalysts employed in this work, Zr- and Hf-TUD-1 and Sn-MCM-41, display mainly Lewis acid properties as demonstrated by characterization with FT-IR analysis of pyridine adsorption, and achieve superior results compared to a reference solid acid catalyst such as Ultrastable zeolite Y. Especially the newly synthesized Hf-TUD-1, showing the highest conversion and turnover among the screened materials, is a promising catalyst for the acetalization of acetone with glycerol in a sustainable process. The excellent performance of these mesoporous catalysts is ascribed to their combination of acidity, wide pores, large specific surface area and relatively hydrophobic surface.