Cathode contamination associative mechanism

Contamination modeling is an important aspect of fuel cell development. It is required to interpolate and extrapolate experimental results to expected conditions in real-world operation, as it is impractical to test all combinations of reactant concentrations and fuel cell operating conditions. Modeling also assists in the development and validation of hypothesized contamination mechanisms. Model development for the anode is more extensive than that for the cathode contamination. The majority of the modeling deals with the kinetic effects associated with adsorption of contaminant species on the cathode and anode catalysts. 

Currently, several air-side contamination models have been published in the literature, ranging from simple empirical and adsorption models to general kinetic models. These models have been applied to simulate and predict SO2, NO2, NH3, and toluene contamination. The kinetic model is a very general one based on the associative oxygen reduction mechanism. It takes into account contaminant reactions, such as surface adsorption, competitive adsorption, and electrochemical oxidation, and has the capability of simulating and predicting both transient and steady state cell performance. The model can be applied to other cathode contaminants, e.g., SO2 and NO2. 

Mechanical action might involve such activities as abrasion, deformation, heat or flame cleaning, and electrocleaning, which involves direct current hydrogen scrubbing at the cathode. Metal-bearing wastes associated with these actions would be due to the metalbearing contamination removed in the process as well as any of the metal substrate removed. 

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