Overview of hydrogen production through iodine sulfur. Process at INET

Thermochemical water-splitting cycles, which use thermal energy to produce hydrogen through the dissociation of water molecules, are promising technologies to produce hydrogen using the heat from nuclear reactor. As an important application of high temperature heat generated by high temperature gas cooled reactor (HTGR), R and D on the hydrogen production through the thermochemical iodine sulfur cycle (IS process) was initiated since 2005 at the institute of nuclear and new energy technology (INET) of Tsinghua University. IS cycle is composed of three reactions: Bunsen reaction, HI decomposition reaction, and sulfuric acid decomposition. Fundamental Studies on these reactions and related techniques, such as separation, concentration and purification, were carried through. In Bunsen section, the kinetics and separation characteristics of H2SO4 phase and HIx phase formed were studied. In HI section, Pt catalysts were prepared by chemical plating and loaded on different supporters, and used in HI decomposition reaction. For HI concentration, electro-electrodialysis (EED) was developed; various parameters affecting the concentration effect were investigated. In sulfuric acid section, new catalysts were developed and employed in SO3 decomposition. Based on the knowledge acquired through the studies on separated section, a closed loop apparatus with the designed hydrogen generation rate of 10NL/h has been established, and the closed cycle test will be carried out soon. This paper presents the current status of IS cycle at INET. In addition, the R and D plan on IS process is also presented. (author)