Development of an electrochemical cell for efficient hydrogen production through the IS process

Mikihiro Nomura, Shin Ichi Nakao, Hiroyuki Okuda, Seiji Fujiwara, Seiji Kasahara, Kazuhiko Ikenoya, Shinji Kubo, Kaoru Onuki

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


The Bunsen reaction (SO2 + I2 + 2H2O = H2SO4 + 2HI) was examined by an electrochemical cell featuring a cation-exchange membrane as the separator, using sulfuric acid dissolving sulfur dioxide as the anolyte and hydriodic acid dissolving iodine as the catholyte. In galvanostatic electrolysis, the molality of H 2SO4 in the anolyte and that of HI in the catholyte were increased up to 17.8 and 14.9 mol kgH2O-1, respectively. These concentrations were far higher than those that were obtained by the Bunsen reaction carried out in the presence of a large amount of iodine (such as I2/HI = 4). I2 concentration after the concentration procedure was at I2/HI = 0.95, which is lower than the reported value. I2 is one of the recycling agents in the IS process. HI and H2SO4 were successfully concentrated under low I 2 concentration. The concentration of HI agreed with the calculated value, based on the amount of electricity consumed, indicating high current efficiency. Heat/mass balance using this type of electrochemical cell through the IS process is discussed for evaluation of the reactor. The thermal efficiency to produce hydrogen was calculated at 42.1%, without heat recovery for electricity, by optimizing HI and H2SO4 concentrations after application of the electrochemical cell.

Original languageEnglish
Pages (from-to)1991-1998
Number of pages8
JournalAIChE Journal
Issue number8
Publication statusPublished - 2004 Aug
Externally publishedYes


  • Bunsen reaction
  • Cation-exchange membrane
  • Electrochemical cell
  • Hydrogen production
  • IS process

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • General Chemical Engineering


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