CHEMOSELECTIVE CATALYTIC-OXIDATION OF GLYCEROL WITH AIR ON PLATINUM METALS

The transesterification of triglycerides extracted from oilseeds to ob tain biodiesel fuel yields up to 14% by weight of glycerol as by-produ ct. The liquid-phase oxidation of glycerol with air on platinum cataly sts was investigated to prepare valuable oxidation products such as gl yceric acid or dihydroxyacetone. The effect of the pH (pH range 2-11) and of different metal catalysts was studied. The selectivity to glyce ric acid can be as high as 70% at 100% conversion on Pd/C at pH 11. On Pt/C catalyst, glyceric acid was still the main product (55% selectiv ity); but the deposition of bismuth on platinum particles orientates t he selectivity towards the oxidation of the secondary hydroxyl group t o yield dihydroxyacetone with a selectivity of 50% at 70% conversion.