Bimetallic AuCu nanoparticles supported on CeO2 as selective catalysts for glycerol conversion to lactic acid in aqueous basic medium

Gold-based catalysts, monometallic Au/CeO2 or bimetallic AuCu/CeO2, evaluated on the glycerol conversion to lactic acid, demonstrated to be active and selective at a reaction temperature of 220 °C in aqueous basic medium at low base concentration. The concentration of NaOH slightly modified the activity of AuCu/CeO2 for converting glycerol, while selectivity toward lactic acid increased on AuCu/CeO2 catalyst but had no influence on Au/CeO2 catalytic performance. Recyclability tests demonstrated that AuCu/CeO2 kept high conversion for up to the fourth catalytic cycle and selectivity remained stable, while conversion on Au/CeO2 significantly decreased in the second cycle. For instance, copper stabilized gold on AuCu/CeO2 catalysts for converting glycerol to lactic acid in aqueous medium at relatively high temperature of 220 °C. Characterization of AuCu/CeO2 catalyst using H2-TPR showed that the presence of Au modified the reduction events of Cu species, while HRTEM analysis of nanoparticles showed particles of an average size of 6.3 nm and lattice fringes for metallic Au and Cu. These results suggest that Au and Cu might be in close proximity.