ABSTRACT
Carbohydrate oxidation by air on supported metal catalysts has received much attention in the past few years. These catalytic reactions are of interest from an industrial standpoint. Thus, the oxidation of glucose on palladium catalysts is highly selective to gluconic acid and might soon supplant the biochemical route to produce this valuable chemical. The best activities and selectivities were obtained on palladium catalysts promoted with bismuth. These reactions are also of interest from an academic point of view. Because they are conducted in the presence of air slightly above room temperature, the metal surface might be completely covered with strongly adsorbed oxygen atoms, which deactivate the catalyst. Palladium catalysts have been designed with well-characterized particle size and particle location on supports. Metal loading by dry impregnation gives mainly particles larger than 3 nm on the external surface of the charcoal grain, whereas ion exchange gives an homogeneous distribution of 1–2.5 nm particles in the pores.
