Enhancement of polymer electrolyte fuel cell tolerance to CO impurities would allow the use of lower quality hydrogen, thus reducing the costs without compromising fuel cell performance. In this work, the effect of carbon monoxide is mitigated by combining different methods, including air bleed, varying the anode flow rate and using a state-of-the-art Pt-Ru catalyst at two operating temperatures. The tolerance was investigated by feeding a novel arrangement of segmented cells with hydrogen containing carbon monoxide less than 20 ppm. Anode exhaust gas was constantly analysed using a gas chromatograph.
It was discovered that increasing the volumetric flow rate of hydrogen and especially utilising ruthenium in the catalyst enhance the carbon monoxide tolerance. When applying the air bleed, an oxygen/CO molar ratio of at least 117 was required to stop the poisoning with a platinum catalyst. Approximately a fifth of the air bleed needed with platinum was enough with Pt-Ru. The results also suggest that when applying air bleed at elevated temperatures, it is beneficial to lower the cell temperature for the duration of the air bleed.
