The oxidation of fructose on Pt/C catalysts. the formation of d-threo-hexo-2,5-diulose and the effect of additives

This paper describes a study on the oxidation of d-fructose with molecular oxygen on Pt/C catalysts. Two major products are formed: 2-keto-d-gluconic acid and d-threo-hexo-2,5-diulose (‘5-ketofructose’). Deactivation of the catalyst was observed, caused both by overoxidation of the active surface and inhibition of the reaction by 2-ketogluconic acid. Although promotion of the catalyst with bismuth did not prevent deactivation, it improved the selectivity to 2-ketogluconic acid, probably due to coordination of fructose to the promoter. Other promoting metals (tin, lead and antimony) and additives like borate and hexamethylenetetramine were less successful.