Massive and efficient H production technology on thermochemical water-splitting iodine-sulfur process

Takegami, Hiroaki ; Tanaka, Nobuyuki ; Noguchi, Hiroki  ; Kamiji, Yu; Iwatsuki, Jin ; Myagmarjav, O.  ; Inagaki, Yoshiyuki; Kubo, Shinji  

A thermochemical water-splitting iodine-sulfur process offers the potential for the mass production of hydrogen at high levels of efficiency. This chemical process uses high-temperature heat sources such as the high-temperature gas-cooled reactors, solar heat, and waste heat. Raw materials of HO splits into H and O with combining three chemical reactions using sulfur and iodine compounds. Currently important R&D tasks are to verify integrity of components made of practical-structural materials and stability of hydrogen production operation in the harsh working conditions, and to develop methods for high thermal efficiency. A test facility of hydrogen production was constructed applying corrosion-resistant components developed using industrial materials. The entire process connecting the three process chemical sections was operated in hydrogen production for 31 hours at rate of 20 L / h. Through the operations, technical issues were obtained that prevention of clogging and leakage are important for next longer operation. For improvement of thermal efficiency, membrane technologies have been devised for HI decomposition section, HSO decomposition section, and Bunsen reaction section. Permselective membranes (H, O) and a cation exchange membrane were developed to adopt to membrane reactors which work to increase chemical equilibrium and to reduce processing energy of chemical reactions.