(182b) Novel Approach to CO2 Utilization for Power Generation Using An Electrochemical Reactor

Recent interest in anion exchange membrane fuel cells (AEMFC) has been fueled mainly by the ability to use non-noble metal catalyst in alkaline media. Also, fuel oxidation does not require water and alcohol versions can operate on pure fuel, and anion electroosmotic drag suppresses fuel crossover. Finally, water management is potentially simplified since water is produced in the anode and partially consumed at the cathode. However, one of the main drawbacks of the hydroxide exchange membrane fuel cell is electrolyte degradation via Hofmann elimination and nucleophilic attack catalyzed by the presence of hydroxide. Operation in the carbonate cycle has been proven and suggested as a way of improving durability and power density [1,2]. In this work, the performance of an AEMFC was improved with the presence of CO2 in the cathode stream, suggesting that carbonate was being produced at the cathode [3]. This study found that use of carbonate ions does not affect chemical integrity and ionic conductivity of commercially available anion exchange membranes, while considerable degradation was found when using hydroxide anions. Hydrogen oxidation was possible using carbonate anions, following a 2-electron pathway and not affecting the exchange current density compared to hydroxide. Therefore, operation of a room temperature carbonate fuel cell that reacts oxygen and carbon dioxide to produce carbonate appears to be a viable option. The reactor will result in increased power output and electrolyte life compared to hydroxide exchange membrane fuel cells.

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