Sulfur-iodine cycle decomposition

Ozturk, I.T. et al, An improved process for H2S04 decomposition of the sulfur-iodine cycle, Energ. Corners. Manag., 36,11,1995. 

Huang, C., Raissi, T.-A. 2005. Analysis of sulfur-iodine thermochemical cycle for solar hydrogen production. Part I decomposition of sulfuric acid. Solar Energy 78 632-646. 

Huang, C., and T-Raissi, A., Analysis of Sulfur-Iodine Thermochemical Cycle for Solar Hydrogen Production. Part I - Decomposition of Sulfuric Acid, Solar Energy, 78(5), 632-46,2005. 

Several studies of H2 production by thermochemical processes have been presented recently, including reports of several cycle statues such as sulfur—iodine (S—I) cycle, ISPRA Mark 9 cycle, hybrid sulfur cycle, Ca—Br cycle, Cu—Cl cycle, and adiabatic UT-3 cycle (Rosen, 2010). Many of these cycles are driven by nuclear or solar energy sources. H2O thermal decomposition generally holds three distinct steps production of H2, production of O2, and material regeneration. In recent decades, thermochemical cycles have been used for H2O decomposition, because they allow appreciable amounts of H2 and O2 to be attained at lower temperatures (usually less than 1000 °C) than are needed for one-step fliermochemical H2O decomposition (Rosen, 2008, Rosen, 2010). 

Many problems have been reported (163), and the process has been abandoned because of the difficulty in handling sohds. Processes which are thought to have the best likelihood of success ate based on sulfuric acid decomposition. Three prominent cycles are based on this reaction the General Atomics iodine—sulfur cycle... 

A bench-scale test facility for hydrogen production using the thermochemical iodine-sulfur (IS) process has been established at JAERI to verify the hydrogen production, to study the conditions for the reactions, and to gain experience for a large-scale plant [74]. The three reactions (see appendix A.2.3.) are performed in separate sections of the apparatus, the Bunsen reaction and the sulfuric acid decomposition at the same time to avoid SO2 storage (see Fig. 4-8). The process requires temperatures of 800 to 900 °C. Its feasibility was successfully demonstrated in a glass, quartz, and teflon lab-scale apparatus. In the course of six cycles completed, the total amounts of H2 and O2 produced were 16.4 1 and 9.9 1, respectively. The thermal efficiency achieved, however, was much smaller than the theoretical one of 47 - 50 % [44]. In late 1997, the continuous operation of the IS process cycle as a closed loop over 48 h resulted in the production of 44.8 1 of H2 [75]. 

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