Catalytic decomposition of sulfur trioxide on the binary metal oxide catalysts of Fe/Al and Fe/Ti Original Research Article

The iodine–sulfur (IS) cycle has been focused for hydrogen production by water splitting using a very high temperature nuclear reactor (VHTR) which is a high temperature heat source. The nuclear energy was absorbed at the temperature ranges of 750–900 °C by SO3 decomposition reaction to SO2 and O2 in IS cycle. In this work, the activity of Fe/Al and Fe/Ti catalysts prepared by a co-precipitation was studied in an attempt to find some suitable catalysts for the decomposition of sulfur trioxide as the oxygen-generating reaction in the thermo-chemical water splitting process. The SO3 decomposition was performed in the temperature range of 750–950 °C at a space velocity of 72,000 cm3/g cat. h in a fixed bed reactor. The catalytic activity of Fe/Al and Fe/Ti catalysts increased with an increase in Fe loadings, indicating that the Fe component should be active. The mechanism for the SO3 decomposition on metal oxides can be described as follows: the metal sulfate formation (MO + SO3 → MSO4) and the decomposition of metal sulfate (MSO4 → MO2 + SO2 and MO2 → MO + 1/2O2).