Controlled preparation and characterization of supported CuCr2O4catalysts for hydrogenolysis of highly concentrated glycerol

Abstract

Supported Cu–Cr catalysts were prepared by a non-alkoxide sol–gel route, and characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), H₂-temperature programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) measurement. Their structures were significantly tuned by the Cu–Cr molar ratio. CuCr₂O₄, CuCr₂O₄–CuO and CuCr₂O₄–Cr₂O₃ structures were confirmed in CuCr(0.5), CuCr(4) and CuCr(0.25) catalysts, respectively. A direct interaction between CuCr₂O₄ and CuO or Cr₂O₃ in CuCr(4) and CuCr(0.25) catalyst was observed by the H₂-TPR and XPS results. The catalytic performance of Cu–Cr catalysts with various structures was examined by hydrogenolysis reaction of high concentrated glycerol. Under mild conditions (2.0 MPa and 130 °C) and high concentration (100 wt%), the maximum conversion (52%) was obtained over the CuCr(0.5) catalyst, while the CuCr(4) catalyst gave the highest selectivity of 1,2-PD (up to 100%). This finding will result in the production of less waste water and lower energy consumption in the following separation steps during glycerol hydrogenolysis.