Thermodynamic considerations on the purification of HSO and HIx phases in the iodine-sulfur hydrogen production process

Wang, L.*; Imai, Yoshiyuki  ; Tanaka, Nobuyuki ; Kasahara, Seiji  ; Kubo, Shinji  ; Onuki, Kaoru

Small amount of HI and I are contained in HSO phase and a little HSO is contained in HIx phase obtained from the Bunsen reaction in the thermochemical water splitting IS process. A thermodynamical investigation of purification to separate and recover these components was made by a chemical process simulator ESP to clarify effects of temperature and stripping gas on reaction and phase equilibrium. The reverse Bunsen reaction, which change HI to I, and I vaporization are dominant at higher temperatures than ca. 110C for HSO phase. The temperature can be extended to be lower by inert gas stripping. Purification of the solution without loss of HSO is expected by oxidation of HI to I by O stripping. Though temperature range where purification by reverse Bunsen reaction is available is limited for HIx phase because of S and HS production reactions, the range can be widen by inert gas stripping.