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Subject Area(s)

Chemical Engineering


The thermochemical cycle involving the interconversion between sulfur dioxide and sulfuric acid is a promising method for efficient, large-scale production of hydrogen. A key step in the process is the oxidation of sulfur dioxide to sulfuric acid in an electrolyzer. Gaseous SO2 fed to a proton exchange membrane (PEM) electrolyzer was previously investigated and was shown to be a promising system for the electrolysis step. A critical factor in the performance of this gas-fed electrolyzer is the management of water since it: (i) is needed as a reactant, (ii) determines the product sulfuric acid concentration, (iii) affects SO2 crossover rate, and (iv) serves to hydrate the membrane. Therefore, we present a coupled mathematical and experimental study on the effect of water on the production of sulfuric acid in a gas-phase PEM electrolyzer. The model is shown to successfully predict the concentration of sulfuric acid as a function of temperature, current density, pressure differential across the membrane, and membrane thickness.


© The Electrochemical Society, Inc. 2009. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in the Journal of the Electrochemical Society.

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DOI: 10.1149/1.3001923