Rechargeble PEM FC using cyclohexane and 2-propanol as fuels.

Abstract

The direct methanol fuel cell systems have already proved to be feasible for portable applications. However, there are still some drawbacks in the direct methanol fuel cells such as low electrocatalytic activity of the anodes, CO poisoning on Pt-based anode catalysts, and permeation of methanol through the PEM. To overcome these problems, we applied cyclic hydrocarbons (such as cyclohexane, methylcyclohexane, and tetralin) and secondary alcohols (such as 2-propanol and 2-butanol) to the direct PEM fuel cell (D-PEMFC) system. The dehydrogenation and hydrogenation of cyclic hydrocarbons is reversible and the fuels are regenerative and recyclable, thus the ‘rechargeable’ D-PEMFC is available by combination with electrolysis of H₂O and electrochemical hydrogenation of hydrocarbons. Based on this background, we applied cyclic hydrocarbons and secondary alcohols to D-PEMFC, and observed the polarization curves of the electro-oxidation of cyclic hydrocarbons. High performance of the PEM fuel cell was achieved by using 2-propanol and 2-butanol as fuels with zero- CO₂ emission and lower-crossover through PEM than with a methanol-based fuel cell. The performance of cyclohexanewas lower than those of alcohols, but the crossover of cyclohexane was significantly small, presumably due to the hydrophobicity of cyclohexane. The electro-reduction of acetone and water electrolysis mediated by the PEM was carried out at 80°C. Using Pt/C, PtRu/C and Pt black catalysts, 1–3% of conversions of acetone were observed.