The conversion of glycerol to lactic acid catalyzed by ZrO2-supported CuO catalysts

Zirconia-supported copper oxide catalysts with various compositions were prepared and characterized by atomic absorption spectroscopy, N-2 physical adsorption, temperature programmed reduction, powder X-ray diffraction and X-ray photoelectron spectroscopy. These catalysts were evaluated for the conversion of glycerol to lactic acid in aqueous solution in the presence of a base and under an inert atmosphere. The results showed that CuO/ZrO2 with 30% Cu loading exhibited the highest activity for the conversion of glycerol. Under optimum conditions, 100% glycerol conversion and 94.6% selectivity for lactic acid were obtained over 30%CuO/ZrO2 when reacting 10 mL of glycerol solution (1.4 M), using 0.2 g catalyst in the presence of NaOH (1:1 NaOH/glycerol molar ratio) at 453 K and 1.4 MPa N-2 for 8 h. Moreover, the reusability of 30%CuO/ZrO2 was investigated, and a reaction mechanism for the conversion of glycerol is proposed. (C) 2015 Elsevier B.V. All rights reserved.