Electrochemical oxidation of 1-methoxy-2-propanol in direct liquid fuel cells

Some interesting features have been observed when 1-methoxy-2-propanol was studied in direct liquid fuel cells. Air flow rate ranging from 180 to 920 ml/min had no effect on performance, but the performance increased largely when the cell temperature was increased from 40, to 60, and then to 80 °C. The open circuit voltage of the cell was around 0.70 V, which was 0.08–0.33 V higher than that when methanol was used. At low air flow rates, 1-methoxy-2-propanol performed much better than methanol in the entire current density region at 60 and 80 °C. At high air flow rates, methanol performed better than 1-methoxy-2-propanol at current densities higher than 100 mA/cm2, but the latter performed better than the former at current densities less than ca. 50 mA/cm2. The crossover current density of 1.0 M 1-methoxy-2-propanol through a Nafion® 112 membrane was estimated electrochemically, and it was 25.6, 60.8 and 96.0 mA/cm2 at cell temperatures of 40, 60, and 80 °C, respectively, measured at 0.90 V. These numbers were much smaller than those of methanol that, e.g. had a crossover current density of 232 mA/cm2 at 0.9 V and 60 °C. One problem with using 1-methoxy-2-propanol as a fuel was that the cell anode seemed to be seriously poisoned by the oxidation intermediates at anode overpotentials lower than ca. 0.2 V.