EVALUATION OF ETHANOL, 1-PROPANOL, AND 5-PROPANOL IN A DIRECT OXIDATION POLYMER-ELECTROLYTE FUEL-CELL - A REAL-TIME MASS-SPECTROMETRY STUDY

Ethanol, 1-propanol, and 2-propanol have been evaluated as alternative fuels for direct methanol/oxygen fuel cells. The relative product dis tributions for the electro-oxidation of these alcohols under fuel-cell conditions were determined using on-line mass spectrometry. For water /ethanol mole ratios between 5 and 2, ethanal is the main product, whi le CO2 is a minor product. However, an increase of the water/ethanol m ole ratio increased the relative product distribution of CO2 slightly Propanal was the main product of the electro-oxidation of 1-propanol w ith a similar percentage of CO2 being formed as for ethanol. In contra st, the electro-oxidation of 2-propanol yielded practically only aceto ne. Between 150 and 190 degrees C, the product distributions for the e lectro-oxidation of ethanol, 1-propanol, and 2-propanol do not depend significantly on the temperature. No differences in the product select ivities of Pt-Ru and Pt-black were found. Ethanol is a promising alter native fuel for direct methanol fuel cells (DMFCs) with an electrochem ical activity comparable to that of methanol. Conversely, 1-propanol a nd 2-propanol are not suitable as fuels for DMFCs due to their low ele ctrochemical activity.