Glycerol oxidation on gold catalysts supported on group five metal oxides—A comparative study with other metal oxides and carbon based catalysts

V2O5, Nb2O5 and Ta2O5 were used as supports for gold and their activity in the oxidation of glycerol was compared with that of gold loaded on Al2O3, TiO2 and carbons. Different methods of gold loading were applied and they determined the gold particle sizes. The gold-sol method used for the modification of oxides ensured high gold dispersion and smaller Au crystallites than the deposition–precipitation one. The influence of acid–base properties of the supports on gold particle sizes and activity in oxidation of glycerol was considered. Au/Nb2O5 catalyst, prepared by gold-sol method and crystalline niobia as support, was attractive for the liquid phase oxidation of glycerol showing high selectivity to glyceric acid and the ability of reuse. Its catalytic properties in this process were comparable with those noted for Au loaded on carbon. A significant difference between the amorphous and crystalline niobia used as supports of gold was established and better performance of anhydrous crystalline Nb2O5 was shown.