Enhancing the catalytic activity and selectivity of the partial oxidation of methanol by electrochemical promotion

Abstract

This paper reports for the first time the simultaneous production of H2 and H2CO via partial oxidation of methanol over an electrochemically promoted Pt catalyst film. The effect of the Pt catalyst film preparation technique (pulse cathodic arc vs. impregnation), reaction conditions (temperature and O2/CH3OH ratio), and the durability of the system for long working times have been investigated for the methanol partial oxidation reaction over a Pt/K-βAl2O3 electrochemical catalyst. It is shown that for a cationic solid electrolyte system, an excess of electrocatalytic activity of the catalyst-electrode film could be detrimental for the electro-promotional effect due to the ability of the porous film (e.g., impregnated film) to form and store surface compounds. However, the catalytic activity and selectivity of a more dense Pt film (e.g., prepared by the cathodic arc technique) could be strongly enhanced by electrochemical promotion. Under optimal potential conditions (a potassium promoter coverage of 0.1), the H2 and the H2CO production rates were increased by a factor of 6 and 4, respectively. The catalytic performance of the system was stable for long working times under polarization, which may have significant importance since it allows to produce both products at mild reaction conditions and in a single reaction step.