PEMFC contaminant tolerance limit—CO in H2

Equations are derived from a generic, transient PEMFC contamination model to predict the effect of CO contaminant concentration in H2 on both steady state performance losses and time constants. The resulting predictions allowed determination of the CO tolerance limit for the cases of a Pt and WC catalyst under specific operating conditions. An increase of the International Organization for Standardization CO tolerance limit of 0.2 ppm is possible because the CO concentration leading to a steady state performance loss of less than 1% is estimated at 0.2–0.9 ppm. An increase in CO tolerance limit is expected to reduce the analytical verification cost (quality control). The steady state performance loss is independent of catalyst loading thus avoiding a future standard change resulting from PEMFC cost reduction activities.