OXIDATION OF GLUCOSE AND GLUCONATE ON PT, PT BI, AND PT AU CATALYSTS

Glucose and gluconate aqueous solutions (2 mol/l) were oxidized with a ir (atmospheric pressure, 333K, pH 7) on active charcoal-supported, pl atinum catalysts (catalytic ratios substrate/Pt greater than or equal to 787); some catalysts were promoted with bismuth or gold. The activi ty of unpromoted Pt/C catalysts for glucose oxidation was comparable w ith that of Pd-Bi/C catalysts and there was no deactivation; gluconate formed transiently was oxidized into glucarate, the final selectivity did not exceed 50%. The oxidation of gluconate on very well dispersed Pt catalysts prepared by cationic exchange or anionic adsorption lead s to higher glucarate selectivities than those previously reported, in spite of the fact that the present solutions were much more concentra ted and reduced amounts of platinum were used. Addition of bismuth ada toms by surface redox reaction produces a shift in selectivity towards 2-ketogluconate. Addition of gold adatoms on platinum decreases the c atalyst deactivation.