Synthesis of Cu-based catalysts for hydrogenolysis of glycerol to 1,2-propanediol with in-situ generated hydrogen

This study focuses on the "green" conversion of glycerol to 1,2-propanediol using the Cu-Al-Zn catalyst prepared by the co-precipitation method. Different ratios of (Cu+Zn)/Al were synthesized; the Zn and Al contents were varied while the Cu was kept constant (the Zn/Al ratios were 3:1, 4:1, 5:1, and 6:1). Catalyst characterization using TPD, XRD, and SEM, showed that the synthesized catalysts consisted of hydrotalcite with basic and acidic sites. The basicity of the catalysts was found to be an important criterion for the catalytic transfer hydrogenation, with the basic sites of the catalyst increasing the conversion of glycerol. Copper appeared to have an impressive effect on the C-O/C-C cleavage of glycerol during indirect hydrogenolysis for the synthesis of 1,2-propanediol. A reaction mechanism based on the hydrogenation of ethanol at Cu sites and the formation of intermediates at the basic sites of the catalysts was proposed.