Conversion of glycerol to dihydroxyacetone over Au catalysts on various supports

BACKGROUND Glycerol, which is a coproduct of biodiesel production, has been identified as a key platform compound for producing various valuable chemicals. The selective catalytic oxidation of glycerol to dihydroxyacetone is very attractive. RESULTS A series of Au catalysts supported on metallic oxides, i.e. ZnO, CuO, Al2O3, Fe2O3 and NiO, were studied for selective catalytic oxidation of glycerol to dihydroxyacetone under base-free conditions. Among the catalysts, Au/CuO showed the best catalytic activity (glycerol conversion of 89% and dihydroxyacetone selectivity of 82.6% at 80 degrees C under 10 bar of O-2), followed by Au/ZnO >> Au/NiO > Au/Al2O3 approximate to Au/CuO-SD approximate to Au/Fe2O3. The catalytic behaviors of these supported Au catalysts varied depending on the Au particle size, Au oxidation state, Au-support interactions and lattice oxygen reducibility. CONCLUSION The main reasons for the high catalytic activity of Au/CuO are as follows. Firstly, the catalyst has small metallic Au particles, which are more active in cleavage of the secondary C-H bond in glycerol molecules. Secondly, the interactions between Au and CuO facilitate lattice oxygen reduction, and this increases oxygen mobility, which may promote regeneration of Au-support perimeter active sites by gaseous oxygen. (c) 2019 Society of Chemical Industry