Effect of pH in the Pt-catalyzed oxidation of d-glucose to d-gluconic acid

Abstract

The pH effect on the Pt-catalyzed selective heterogeneous oxidation of d-glucose to d-gluconic acid was studied. The oxidation reactions were performed in the pH range 2 to 9 in a batch reactor using 5% Pt/C as the catalyst while monitoring the progress of the oxidation reaction. Accurate analysis of all products is offered. Inhibition of the catalytic activity was observed in acidic medium. The nature of the poisoning species is discussed taking into account the results obtained from electrocatalytic studies. Probably d-gluconic acid formed during the oxidation reaction is responsible for the poisoning of the catalyst. When adding bismuth as a promotor, the consecutive reaction towards 2-d-ketogluconic acid takes place and the poisoning in acidic medium is much less pronounced. © 1995.