The selective oxidation of 1,2-propanediol to lactic acid using mild conditions and gold-based nanoparticulate catalysts

The use of bio-renewable resources for the generation of materials and chemicals continues to attract significant research attention. It is well established that glycerol is an excellent starting material for the production of 1,2-propanediol by dehydration/hydrogenation and that this can subsequently be oxidised to lactic acid, which has the potential to be used as a major chemical in the production of biodegradable polymers. Previous studies using gold catalysts for the oxidation of 1,2-propanediol have used elevated temperatures and pressures. We now show that the oxidation of 1,2-propanediol to form lactic acid can be carried out selectively under mild reaction conditions with gold–platinum catalysts prepared using a sol-immobilisation method, with activated carbon as the support. Carrying out the reaction at ambient temperature with air significantly improves the reaction in terms of its environmental impact and its industrial attractiveness, as lactic acid can be obtained with high selectivity.