Selective Hydrogenolysis of Glycerol over Bifunctional Copper-Magnesium-Supported Catalysts for Propanediol Synthesis

Abstract

In the present study, bimetallic Cu-Mg-supported silica catalysts were prepared by a chemisorption-hydrolysis method with different loadings of copper/magnesium and used for glycerol hydrogenolysis for 1,2-propanediol (1,2-PDO). The Cu catalyst with the base as a promoter showed the highest activity for glycerol hydrogenolysis reaction (glycerol conversion 89.5% and 1,2-PDO selectivity 92.1%). The copper seemed to significantly affect the C-C cleavage and C-O cleavage of glycerol for 1,2-PDO formation. The synthesized catalysts were characterized by N-2 sorption, X-ray diffraction (XRD), temperature-programmed desorption of NH3 (TPD-NH3), temperature-programmed reduction of H-2 (TPR-H-2), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), CO chemisorption, Fourier transform infrared (FTIR), and IR analyses of absorbed pyridine. It was found that MgO content influenced the activity of the Cu-supported catalyst. Glycerol hydrogenolysis was found to be highly dependent upon the acidity and reducing property of Cu-Mg-supported silica catalysts. The high catalytic performance of the Cu-Mg-supported/silica catalyst was attributed to the copper dispersion and the existence of Cu+ species and acidic sites. The 1,2-PDO selectivity and glycerol conversion may be easily tuned by the Cu/Mg molar ratio.