Catalytic thermal decomposition of sulphuric acid in sulphur-iodine cycle for hydrogen production

Zero emission energy production systems are the main goal of engineering and research efforts. The use of hydrogen is the most suitable option, and hydrogen production by water using renewable energy power supply could be the final solution. In this study the sulphur–iodine cycle for hydrogen production by a water-splitting reaction has been investigated and new experimental results on thermal dissociation of sulphuric acid has been discussed. The decomposition of H2SO4 to produce SO2 is the reaction with the highest energy demand in the S–I cycle and it shows a large kinetic barrier. In this work, two catalysts, a Pd–Ag alloy and ferric oxide (Fe2O3), have been tested to evaluate their effect on dissociation efficiency at various temperatures. For both catalysts a large onset temperature decrease for the activation of this reaction has been achieved. In the case of the intermetallic alloy Ag–Pd it may be suggested that the metal oxide PdO could be the active catalytic species.