Pure silica Beta zeolite supported copper species for efficient hydrogenolysis of glycerol to 1,2-propanediol

Catalytic conversion of glycerol to 1,2-propanediol is an important issue for sustainable production of fine chemicals and biodiesel. Here it is found that pure silica Beta zeolite supported copper species via hydrothermal treatment (Cu/Si-Beta-HT) are highly efficient for hydrogenolysis of glycerol to 1,2-propanediol, achieving 96.0% conversion and more than 99.9% selectivity after reaction at 240 °C for 3 h. TEM images and N2O titration experiments confirm the high dispersion of Cu nanoparticles in the catalyst. In addition, pyridine-adsorption FT-IR spectra and NH3-TPD profiles suggest the presence of copper species as Lewis acidic sites in the catalyst. The hydrogenolysis of glycerol to 1,2-propanediol mainly includes the dehydration of glycerol to acetol and hydrogenation of acetol into 1,2-propanediol, which are catalyzed by copper cations and Cu nanoparticles, respectively. In situ FT-IR spectra and kinetic studies suggest that the dehydration rate is slower than the hydrogenation rate, and the dehydration is a key step for the hydrogenolysis of glycerol to 1,2-propanediol.