Optimization of liquid–liquid phase separation characteristics in the Bunsen section of the sulfur–iodine hydrogen production process

In order to optimize the sulfur–iodine thermochemical cycle, a series of experiments were conducted to investigate the separation characteristics of the liquid–liquid phase in the H2SO4/HI/I2/H2O quaternary solution produced by Bunsen reaction. The effects of the solution composition in the feed and the operating temperature on the separation characteristics were analyzed to determine the preferable operating conditions in the Bunsen section. The increases in both the iodine content and the operating temperature improved the separation characteristics of the liquid–liquid phase when the occurrence of secondary reactions was neglected. The amount of impurities in both phases obviously decreased as the iodine content increased. The effect of the iodine content was more significant relative to that of the operating temperature. The optimal operating conditions were proposed to achieve the concentrations of HI in the HIx phase in excess of the azeotropic composition.

► Liquid–liquid phase separation in the Bunsen section is investigated. ► Separation properties improve as the iodine content and temperature increase. ► The impurities in both phases reduce as the iodine content increases. ► The iodine content is more important relative to temperature. ► The optimal operating conditions of Bunsen section are proposed.