Apparent Kinetic Study On The Reverse Bunsen Reaction In The Iodine-Sulfur Thermochemical Cycle

Clean and large-scale production of hydrogen using nuclear or renewableenergy is essential for the development of hydrogen energy. Theiodine-sulphur cycle, with its many merits, is considered as one of the mostpromising ways for nuclear hydrogen production.However, the side reactions between H₂SO₄and HI which produced byBunsen reaction, one of the three reactions of which IS cycle is composed,may cause some problems for the purification process of the two acids. Inorder to optimize the process conditions, it is necessary to perform kineticstudy on the major side reactions and the reverse Bunsen reaction.In this work, a preliminary kinetic study has been carried out.Firstly, the analysis methods for the major species in related reactionshave been established. An iodide ion selective electrode （ISE） FIA system hasbeen built to monitor the concentrations of iodide on line. And feasibleapplication of iodide ISE has been investigated. Also, operating conditions ofgas chromatography have been optimized for the determination of H₂S andSO2.Secondly, a set of home-made instrument, which is suitable for thekinetic research in corrosion solutions, was designed, built and improved.By the method of initial rate, kinetic parameters have been determinedAs for I^-, the apparent reaction order is about1.77, while the orders of H⁺andSO₄^2-stand at7.78and1.29, respectively. The apparent rate constant at86℃is2.949*10^-11min^-1*（mol/L）^-9.84approximately. The results indicate thatconcentration of H+has much significant influence on the reaction rate andpurification than that of SO₄^2-and I^-.Such basic data have been provided for the concern of related processdesign and further kinetic study.