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 distributions 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, while CO2 is a minor product. However, an increase of the water/ethanol mole ratio increased the relative product distribution of CO2 slightly Propanal was the main product of the electro-oxidation of 1-propanol with a similar percentage of CO2 being formed as for ethanol. In contrast, the electro-oxidation of 2-propanol yielded practically only acetone. Between 150 and 190 degrees C, the product distributions for the electro-oxidation of ethanol, 1-propanol, and 2-propanol do not depend significantly on the temperature. No differences in the product selectivities of Pt-Ru and Pt-black were found. Ethanol is a promising alternative fuel for direct methanol fuel cells (DMFCs) with an electrochemical activity comparable to that of methanol. Conversely, 1-propanol and 2-propanol are not suitable as fuels for DMFCs due to their low electrochemical activity.