Insight into effect of acid/base nature of supports on selectivity of glycerol oxidation over supported Au-Pt bimetallic catalysts

Au-Pt bimetallic catalysts were supported on different supports, including acidic (TiO2 and CeO2), basic (MgO, Mg(OH)2, (MgCO3)4Mg(OH)2, ZnO, and CaCO3), and amphoteric (Al2O3 and hydrotalcite) supports with the aim to study the effect of the acid/base properties of supports upon the performance of Au-Pt bimetallic catalysts in glycerol oxidation. The results showed that these properties significantly affected the selectivity of products. The selectivity to glyceraldehyde was inversely proportional to the strength of supports' basic sites, and the selectivity to tartronic acid (or glycolic acid, or glyoxalic acid) was proportional to the strength of basic sites. In contrast, the selectivity to glyceric acid was neither proportional to the strength of basic sites nor proportional to the strength of acid sites. The doping of another weaker basic site also affected the selectivity to glyceric acid. Furthermore, the role of the acid/base nature of the supports in affecting the products' distribution is proposed.