Chemically Enhanced Separation of H₂S0₄/HI Mixtures from the Bunsen Reaction in the Sulfur−Iodine Thermochemical Cycle

Abstract

The Bunsen reaction identifies the chemical formation of sulfuric acid and hydriodic acid when sulfur dioxide is oxidized by molecular iodine in aqueous solutions. This reaction occurs spontaneously in a temperature range of 293−373 K and is one of the three steps of the sulfur−iodine thermochemical cycle capable of producing hydrogen from water. In order to attain this, the handling of the H2SO4/HI mixture is crucial for the thermal decompositions which follow. In our study, we propose an innovative way to separate the acids by using an intermediate insoluble sulfonic acid which forms during the process. This procedure results in two main advantages: (1) the common problem of large quantities of iodine in excess is avoided and (2) less water is used.