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In this work, the behavior of a polymer electrolyte membrane (PEM) fuel cell with a Pt/Ru anode exposed to mixtures is investigated. A compact, isothermal one-dimensional model is derived to address the phenomena occurring at the along-the-channel direction. Besides material balances for the anode channel and electrode, the model considers charge balances for the membrane (Laplace equation) and both the anodic and cathodic double layers. The model predicts the formation of complex spatiotemporal patterns for a wide range of technical relevant operating conditions. The system can be understood as a chain of coupled oscillators. The electrical coupling is influenced by the electrolyte conductivity. Furthermore, the system features coupling by the anode gas channel dynamics. Depending on the ratio of the characteristic time for CO transport in the gas channel and the characteristic time required for CO adsorption, two limiting cases with varying degrees of complexity exist. The qualitative theoretical results of the present contribution give a guideline for the design of a validating experiment and pave the way for a systematic experimental analysis.

Recently, an approach involving electrochemical preferential oxidation (ECPrOx) of CO was suggested as having the potential to replace the PrOx concept for deep CO removal from reformate gas in proton exchange membrane (PEM) fuel cells. The first part of this paper deals with the characterization of such an ECPrOx unit from a reaction engineering point of view. Based on a spatially lumped, isothermal model, the qualitative selectivity-conversion behavior is discussed for varying feed flow rates and CO inlet mole fractions. A simple two-phase mechanism is suggested that explains the findings. The second part of the contribution considers qualitative questions on cascading of two ECPrOx reactors. The crucial importance of the configuration of their electrical connection is demonstrated and explained. While two cells connected electrically in parallel exhibit almost the same selectivity-conversion behavior in comparison with a single cell, an electrical series connection enables a considerable increase in the selectivity at the same CO conversion.

In this work, the behavior of a polymer electrolyte membrane (PEM) fuel cell with a Pt/Ru anode exposed to H2/COmixtures is investigated. A compact, isothermal one-dimensional model is derived to address the phenomena occurring at the along-the-channel direction. Besides material balances for the anode channel and electrode, the model considers charge balances for the membrane (Laplace equation) and both the anodic and cathodic double layers. The model predicts the formation of complex spatiotemporal patterns for a wide range of technical relevant operating conditions. The system can be understood as a chain of coupled oscillators. The electrical coupling is influenced by the electrolyte conductivity. Furthermore, the system features coupling by the anode gas channel dynamics. Depending on the ratio of the characteristic time for CO transport in the gas channel and the characteristic time required for CO adsorption, two limiting cases with varying degrees of complexity exist. The qualitative theoretical results of the present contribution give a guideline for the design of a validating experiment and pave the way for a systematic experimental analysis.

Recently, an approach involving electrochemical preferential oxidation (ECPrOx) of CO was suggested as having the potential to replace the PrOx concept for deep CO removal from reformate gas in proton exchange membrane (PEM) fuel cells. The first part of this paper deals with the characterization of such an ECPrOx unit from a reaction engineering point of view. Based on a spatially lumped, isothermal model, the qualitative selectivity-conversion behavior is discussed for varying feed flow rates and CO inlet mole fractions. A simple two-phase mechanism is suggested that explains the findings. The second part of the contribution considers qualitative questions on cascading of two ECPrOx reactors. The crucial importance of the configuration of their electrical connection is demonstrated and explained. While two cells connected electrically in parallel exhibit almost the same selectivity-conversion behavior in comparison with a single cell, an electrical series connection enables a considerable increase in the selectivity at the same CO conversion.