(289ai) Catalytic Decomposition of Sulfur Trioxide with Metallic Catalysts for the Is Cycle of Thermochemical Hydrogen Production
Iodine-Sulfur (IS) thermochemical process is one promising method for hydrogen production by thermochemically splitting water at high temperature. It has been focused as a carbon-free hydrogen production process to overcome the global warming problem and positively expected for industrialization. The IS process is a continuous and closed-cycle system consisting of three steps; (i) Bunsen reaction (I2 + SO2 + 2H2O = 2HI + H2SO4 ; 293-373 K), (ii) HI decomposition (2HI = H2 + I2 ; 473-973 K), (iii) H2SO4 decomposition (H2SO4 = H2O + SO3 → H2O + SO2 + 0.5O2 ; 1073-1173K). Among these, the catalytic decomposition of SO3 to SO2 and O2 is a key reaction using the highest temperature generated from VHTR (very high temperature gas-cooled nuclear reactor). In this work, various metallic catalysts supported on Al2O3 or TiO2 were prepared in various metal contents, and the catalytic activity and thermal durability of each catalyst were compared at the temperature range of 750-950°C in a fixed bed reactor. Concentrated analyses with Fe catalysts were performed since Fe on Al2O3 or TiO2 showed interestingly high performance and thermal resistance.