In this report are the findings into three membrane separation studies for potential application to the Sulfur-Iodine (S-I) thermochemical cycle. The first is the removal of water from hydriodic acid/iodine mixtures. In the S-I cycle, iodine is added to the product of the Bunsen reaction to facilitate the separation of sulfuric acid (H 2 SO 4) from hydriodic acid (HI). The amount of iodine can be as high as 83% of the overall mass load of the Bunsen product stream, which potentially introduces a large burden on the cycle's efficiency. Removal of water from the HI and iodine mixture would substantially reduce the amount of required additional iodine. In this work, performance data for Nafion® and sulfonated poly (ether ether ketone) (SPEEK) membranes is shown. Second, experiments demonstrating the concentration of H 2 SO 4 are detailed. In this work, the positive results of the HI experiments were applied to H 2 SO 4 concentration for use after the decomposition step in which the reaction is equilibrium limited, suggesting that a large portion of the acid remains undecomposed and requiring recycle. Traditional methods including distillation are less desirable for H 2 SO 4 concentration due to corrosion at the liquid-vapor interface. Thus, a concentration system that does not involve boiling the acid is highly desirable. Third, a preliminary study into polymeric membranes that transport hydrogen was conducted. In the HI decomposer, the decomposition of HI yields hydrogen and iodine. To encourage greater conversion, hydrogen should be removed. Many new high performance polymers are capable of transporting hydrogen, one of the most diffusive gases, at temperatures as high as 300 ºC. This task focused on collecting hydrogen permeability data at 300ºC.
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