Synergic effect investigation of carbon monoxide and other compositions on the high temperature proton exchange membrane fuel cell

Abstract

The high temperature proton exchange membrane fuel cell integrated with the methanol steam reformer is a promising technology because it avoids the challenges of high pressure hydrogen storage and refueling. The high temperature fuel cell can tolerate the CO content in the methanol reformate with acceptable performance degradation. However, the synergic effects of CO and other impurities in the methanol reformate on the fuel cell performance need further investigation. This study thoroughly evaluates performances of the high temperature proton exchange membrane fuel cell fed in by mixture of H2, CO and other impurities such as CH3OH, H2O and CO2. The transient voltage, polarization curve, and electrical impedance spectroscopy are in-situ measured. The distribution of relaxation times method is used to characterize different time constants in the impedance spectroscopy. Meanwhile, the equivalent circuit model is developed to represent various reaction processes. The results show that the presence of CH3OH with CO in the fuel gas benefits the fuel cell performance at low current densities but aggravates the CO poisoning at high current densities. The addition of H2O with CO decreases both the Ohmic and anodic charge transfer resistances. The combination of CO2 and CO could enhance the effect of CO poisoning. Moreover, the multi-component methanol reformate test results suggest that the coexistence of multiple impurities in the methanol reformate have positive effect on the fuel cell performance.