The Control of Side Reactions in Bunsen Reaction Section of Sulfur-Iodine Hydrogen Production Process

황-요오드 수소 생산 공정의 분젠 반응 부분에서 부반응 제어

  • Published : 2008.12.30

Abstract

For continuous operation of the sulfur-iodine(SI) thermochemical cycle, which is expected practical method for massive hydrogen production, suggesting operation conditions at steady state is very important. Especially, in the Bunsen reaction section, the Bunsen reaction as well as side reactions is occurring simultaneously. Therefore, we studied on the relation between the variation of compositions in product solution and side reactions. The experiments for Bunsen reaction were carried out in the temperature range, from 268 to 353 K, and in the $I_2/H_2O$ molar ratio of $0.094{\sim}0.297$ under a continuous flow of $SO_2$ gas. As the result, sulfur formed predominantly with increasing temperature and decreasing $I_2/H_2O$ molar ratios. The molar ratios of $H_2O/H_2SO_4$ and $HI/H_2SO_4$ in global system were decreased as the more side reaction occurred. A side reactions did not appear at $I_2/H_2O$ molar ratios, saturated with $I_2$, irrespective of the temperature change. We concluded that it caused by the increasing stability of an $I_{2x}H^+$ complex and a steric hindrance with increasing $I_2/HI$ molar ratios.

Keywords

Sulfur-iodine cycle;Hydrogen production;Bunsen reaction;Side reactions;Phase separation

References

  1. J. H. Norman, G. E. Besenbruch, L. C. Brown, D. R. O'Keefe, and C. L. Allen, "Thermochemical water-splitting cycle: bench-scale investigations and process engineering", GA-A 16713, 1982
  2. S. Kasahara, G. J. Hwang, H. Nakajima, H. S. Choi, K. Onuki, and M. Nomura, "Effects of process parameters of the IS process on total thermal efficiency to produce hydrogen from water", J. Chem. Eng. Japan, Vol. 36, 2003, pp. 887-899 https://doi.org/10.1252/jcej.36.887
  3. S. Kasahara, S. Kubo, K. Onuki, and M. Nomura, "Thermal efficiency evaluation of HI synthesis/concentration procedures in the thermochemical water splitting IS process", Int. J. Hydrogen Energy, Vol. 29, 2004, pp. 579-587 https://doi.org/10.1016/j.ijhydene.2003.08.005
  4. K. Onuki, H. Nakajima, I. Ioka, M. Futakawa, and S. Shimizu, "IS process for thermochemical hydrogen production", JAERI Review 94-006, 1994
  5. V. T. Calabrese and A. Khan, "Polyiodine and polyiodide species in an aqueous solution of iodine +KI: theoretical and experimental studies", J. Phys. Chem, A, Vol. 104, 2000, pp. 1287-1292 https://doi.org/10.1021/jp992847r
  6. M. Sakurai, H. Nakajima, R. Amir, K. Onuki, and S. Shimizu, "Experimental study on side-reaction occurrence condition in the iodine-sulfur thermochemical hydrogen production process", Int. J. Hydrogen Energy, Vol. 25, 2000, pp. 613-619 https://doi.org/10.1016/S0360-3199(99)00074-9
  7. S. Goldstein, J. M. Borgard, and X. Vitart, "Upper bound and best estimate of the efficiency of the iodine sulfur cycle", Int. J. Hydrogen Energy, Vol. 30, 2005, pp. 619-626 https://doi.org/10.1016/j.ijhydene.2004.06.005
  8. J. H. Norman, G. E. Besenbruch, and D. R. O'keefe, "Thermochemical water-splitting for hydrogen production", GRI-80/0105, Gas Research Institute, 1981
  9. J. E. Funk, "Thermochemical hydrogen production: past and present", Int. J. Hydrogen Energy, Vol. 26, 2001, pp. 185-190 https://doi.org/10.1016/S0360-3199(00)00062-8
  10. 이광진, 김영호, 박주식, 배기광, "SI 열화학 수소 제조 공정에서 분젠 반응을 통한 상 분리 특성", 한국수소 및 신에너지학회 논문집, Vol. 19, No. 5. 2008, pp. 386-393
  11. S. Kubo, H. Nakajima, S. Kasahara, S. Higashi, T. Masaki, H. Abe, and K. Onuki, "A demonstration study on a closed cycle hydrogen production by the thermochemical water-splitting iodine-sulfur process", Nucl. Eng. Des., Vol. 233, 2004, pp. 347-354 https://doi.org/10.1016/j.nucengdes.2004.08.025