Effects of operating parameters on the pressurized Bunsen reaction for the integrated operation of sulfur–iodine hydrogen production process

• The characteristics of the pressurized Bunsen reaction was investigated.
• Increasing the pressure enhanced the separation performance of the products.
• The purity of the product improved as the temperature increased.
• Increasing I2 feed concentration inhibited the occurrence of side reaction.
• The extent of Bunsen reaction improved by increasing H2O feed concentration.

The sulfur–iodine hydrogen production process (SI process) is an efficient thermochemical process. Developing composition data of the Bunsen products that are obtained under pressurized conditions is important for the integrated operation of SI process. We investigated the characteristics of the pressurized Bunsen reaction by varying operating parameters (pressure, temperature, I2 and H2O feed concentrations). An HIx solution that consisted of HI, I2 and H2O was used as the reactant. When the pressure increased, the extent of Bunsen reaction was enhanced by increasing the solubility of SO2 gas in the HIx solution. In addition, the amount of H2SO4 phase solution increased due to the decrease in the amount of HIx complex, which has a high degree of hydration. Increasing temperature enhanced the separation performance of the Bunsen products, while the extent of Bunsen reaction decreased. When I2 feed concentration increased, the occurrence of side reaction was inhibited, but the separation performance of the Bunsen products decreased. Although increasing H2O feed concentration was favorable for the pressurized Bunsen reaction, the H2O feed concentration should be controlled by considering the solubility of I2 in the HIx solution.