KINETICS AND MECHANISMS OF THE ELECTROCATALYTIC OXIDATION OF GLYCEROLAS INVESTIGATED BY CHROMATOGRAPHIC ANALYSIS OF THE REACTION-PRODUCTS - POTENTIAL AND PH EFFECTS

The effects of the potential and the pH on the electrocatalytic oxidat ion of glycerol at platinum electrodes were investigated by liquid chr omatography during controlled potential long-term electrolyses. The se lectivity towards the production of glyceraldehyde was found to depend greatly on the applied potential and on the pH of the electrolyte. In an acid medium, the dissociative oxidation of glycerol, leading to fo rmic acid, oxalic acid and glycolic acid, is the main process observed when the potential of electrolysis is set in the so called ''oxygen r egion'' Conversely, the selectivity towards the formation of glycerald ehyde is very high when the applied potential is chosen before the beg inning of the oxidation of the electrode surface. In alkaline medium, very few dissociation products were detected. However the conversion r ate is sensibly increased.