(172e) The Influence of Reaction Conditions On Product Selectivity During the Oxidation of Glycerol Over Supported Gold Catalysts

The selective oxidation of biorenewable alcohols with molecular oxygen over gold catalysts in liquid water offers a sustainable, environmentally-benign alternative to traditional processes that utilize expensive inorganic oxidants and harmful organic solvents. For example, oxidation of glycerol, a byproduct of biodiesel production, to glyceric acid is one possible conversion strategy to form value added chemicals. The oxidation of glycerol by molecular oxygen in the aqueous phase over Au/TiO2 was investigated in both a batch reactor and a continuous upflow fixed bed reactor. The effects of catalyst particle size, gas flow rate, liquid flow rate, reaction temperature, dioxygen pressure, and solution pH were examined in the fixed bed system. The unique hydrodynamics of the fixed bed system allowed for secondary oxidation products such as tartronic acid and oxalic acid to form in substantial amounts, which contrasts the product distribution observed in a batch system. These results suggest that reactor configuration can play an important role in the observed product selectivity from oxidation reactions over highly active gold catalysts.