Effect of trace contaminants on PEM fuel cell performance

At the Hawaii Fuel Cell Test Facility a systematic evaluation of the impact of impurities in hydrogen is underway to evaluate the effects on the performance of PEM fuel cells. Initial tests are being conducted using carbon monoxide and hydrocarbon contaminants. The effects of carbon monoxide poisons at atmospheric and pressurized operating conditions have shown a strong dependence on concentration of the impurity over the range 6.7 mu mole/mole to 29.3 mu mole/mole. Additionally, benzene and toluene were tested at 20 mu mole/mole. Although both benzene and toluene showed no evidence of fuel cell degradation, on-line gas analysis of the exit anode stream showed that toluene hydrogenation occurs in the anode resulting in 90% conversion of the toluene to methyl-cyclohexane.