Electrocatalytic optimization of faradaic yields in the chlorate cell process

Abstract

It has been shown that while the mixed RuO2TiO2 coated titanium anode deteriorates very quickly in the presence of ionic phosphate species, the electrode containing palladium and tin oxides in the coating mixture as well as the former catalyst exhibits almost equal electrocatalytic activity and a high corrosion stability in both dichromate and phosphate buffering systems. Electrocatalytic optimization of faradaic yields over a much wider pH range for the chlorate cell process has been achieved by the mixed ruthenium, palladium, tin and titanium oxide catalysts and in the presence of a phosphate buffer. The effect is tentatively ascribed to the phosphate adsorption associated with further activation polarization (inhibition effect) of the available chlorine oxidation reaction at the anode. Two benefits result therefrom: (a) the pH value can be kept at around pH 7, providing better elemental chlorine absorption, and (b) dichromate buffer can be at least partially replaced by the more convinient phosphate buffering system.