SELECTIVE OXIDATION OF GLYCEROL ON A PLATINUM BISMUTH CATALYST

Dihydroxyacetone was catalytically prepared by selective oxidation of glycerol. Platinum supported on charcoal showed weak catalytic activity for oxidation of the secondary hydroxy group of glycerol especially in an acidic media (pH 2-4) with a dihydroxyacetone yield of 4%. However, incorporation of bismuth in platinum (weight ratio of bismuth vs. platinum = 0.2) increased the dihydroxyacetone selectivity from 10 to 80%. A bismuth submonolayer on Pt(111) with (square-root 3 x square-root 3)R30-degrees structure (surface coverage of bismuth on Pt (111), theta(Bi) = 0.33) is proposed for the catalytic oxidation of the secondary hydroxy group of glycerol molecules. It is postulated that bismuth adatoms function as site blockers on Pt(111), controlling the glycerol orientation towards dihydroxyacetone formation. The application of a fixed-bed reactor increased the glycerol conversion as well as dihydroxyacetone yield. The catalytic method showed a much higher productivity than the conventional fermentation process.