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Description: The proof of concept of SO2 electrolysis for the hybrid sulfur (HyS) process is the second priority research target of the DOE Nuclear Hydrogen Initiative's thermochemical program for FY07. The proof of concept of the liquid-phase option must be demonstrated at the single cell level for an extended run times (>100 hours). The rate of development of HyS will depend on the identification of a promising membrane or an alternative means for controlling sulfur formation. Once successful long-duration operation has been demonstrated, SRNL will develop a multi-cell stack that can be connected to the H2SO4 decomposer being developed by SNL for the S-I ILS for a Hybrid Sulfur Integrated Laboratory-Scale Experiment during FY 2008. During the first quarter of FY07, SRNL continued the component development and membrane development activities with the goal of identifying and characterizing improved electrodes, electrocatalysts, membranes and MEA configurations which could then be tested at larger scale in the SDE test facility. A modified glass cell was fabricated to allow measurements of sulfur dioxide (SO2) transport across membrane samples at elevated temperatures (up to 70 C). This testing also includes evaluating SO2 transport in different sulfuric acid concentrations (30-70 wt%). A new potentiostat/frequency analyzer was installed for determining ionic conductivity of membranes. This instrument enhances our capabilities to characterize membrane, electrocatalyst and MEA properties and performance. Continuing work from FY06, evaluations were preformed on various commercial and experimental membranes and electrocatalyst materials for the SDE. Several different types of commercially-available membranes were analyzed for sulfur dioxide transport as a function of acid strength including perfluorinated sulfonic acid (PFSA), sulfonated polyetherketone-ketone, and poly-benzimidazole (PBI) membranes. Experimental membranes from the sulfonated diels-alder polyphenylenes (SDAPP) and modified Nafion{reg_sign} 117 were evaluated for SO{sub 2} transport as well. These membranes exhibited reduced transport coefficient for SO{sub 2} transport without the ...
Date: December 20, 2006
Creator: Summers, W
Partner: UNT Libraries Government Documents Department