Contamination of PEMFC

There are three main contaminants in PEMFC i.e., hydrocarbon fuel, carbon dioxide and carbon monoxide. For large PEMFC systems, reformed hydrogen is used as a primary fuel. The reformed hydrogen consists of 1 % CO. The reformation reaction can be explained as follows  

This carbon monoxide gets adsorbed on the surface of the platinum catalyst, hence blocking the access of hydrogen to the catalyst sites. The remedy for this problem is the conversion of CO into carbon dioxide using the water gas shift reaction  

CO2 poisoning is less significant than carbon monoxide poisoning, though CO2 reacts with adsorbed hydrides on platinum at anode sites affecting its performance. Even 10 ppm of CO concentration greatly affects fuel cell performance. Hence, it becomes 

the CO constant increases considerably and the functioning of the fuel cell is affected. 

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A large body of work exists on fuel-side contamination of PEMFCs. Much of it is derived from the desire to run FCs on reformate and is focused on CO and HjS. A large fraction of the fuel-side contamination literature focuses on carbon monoxide because of its high concentration in the reformate stream (1-2%)... 

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