Selective Oxidation of Glycerol to Dihydroxyacetone over Pt−Bi/C Catalyst: Optimization of Catalyst and Reaction Conditions

Glycerol selective oxidation to dihydroxyacetone was investigated systematically in a semibatch reactor over Pt−Bi/C catalyst. Catalysts with different metal loadings, supports, and preparation methods were synthesized, characterized, and tested. The sequential impregnation of Pt and then Bi, followed by NaBH4 reduction, was the optimum synthesis method for high glycerol oxidation rate and maximum DHA yield. The optimum catalyst composition was determined to be 3 wt % Pt, 0.6 wt % Bi, supported on Norit Darco 20-40 mesh activated carbon (BET surface area 600 m2/g, average pore size 4 nm, average pore volume 0.53 cm3/g). In addition to the catalyst, the reaction conditions were also optimized by conducting experiments in the range of temperature 30−90 °C, oxygen pressure 0−180 psig, and initial pH 2−12. The optimum reaction conditions were identified as 80 °C, 30 psig, and initial pH = 2. Under these conditions, a maximum DHA yield of 48% was obtained at 80% glycerol conversion. The catalysts were characterized by using BET, ICP-OES, TEM, XRD, and XPS techniques.