Oxidation of glycerol to dihydroxyacetone over highly stable Au catalysts supported on mineral-derived CuO-ZnO mixed oxide

Selective oxidation of glycerol to dihydroxyacetone (DHA) is a promising pathway for glycerol utilization. In order to fabricate a highly stable supported Au catalyst for the reaction, a series of CuO-ZnO mixed oxides derived from different minerals were synthesized. Then, the Au/CuO-ZnO catalysts were prepared by the deposition-precipitation. High yield of DHA (70%) and conversion of glycerol (76%) were obtained over the rosasite-derived Au/CuO-ZnO catalyst. While over the aurichalcite-derived Au/CuO-ZnO catalyst, the yield of DHA was only 20%. By means of XRD, H2-TPR, TEM, XPS, CO2-TPD characterization, it was found that the higher yield of DHA was attributed to the stronger interaction between CuO and ZnO, higher dispersion of Au species, higher content of Au0 and proper amount of surface basic sites. The rosasite-derived Au/CuO-ZnO catalyst also showed good stability and no obvious decrease in reactivity and DHA selectivity could be seen after five recycles. The stable structure of the support not only enhanced the interaction between CuO-ZnO that stabilized the support itself, but also improved the interaction between Au and the support, further stabilizing the particle size and chemical valence of Au.