Kinetic studies of sulfuric acid decomposition over Al–Fe2O3 catalyst in the sulfur-iodine cycle for hydrogen production

The decomposition of H2SO4 to produce SO2 is the reaction with the highest energy demand in the sulfur-iodine cycle and it shows a large kinetic barrier. In the present study, alumina supported iron (III) oxide has been chosen for a detailed kinetic study. Experiments were carried out in the temperature range of 1023 K–1173 K using space hour velocities in the range of 0.146–0.731 kmol/kg-h in a quartz tube double stage continuous flow fixed bed reactor with 98% sulfuric acid feed over alumina supported Fe2O3 catalyst, nitrogen as inert carrier gas. From the homogeneous kinetic analysis, the apparent activation energy (EA) was found to be 138.6 kJ/mol. This high activation energy indicates that the experiments were conducted in a kinetic controlled regime. The catalyst was well characterized by XRD, BET, TPR/TPO, SEM and FT-IR before and after reaction.

► All experiments were conducted in kinetic controlled regime. ► Iron oxide sowed good activity at higher temperature and approached equilibrium conversions. ► Lower partial pressures and lower space velocities gives better yields of SO3. ► Apparent activation energy found to be 138.6 kJ/mol from the homogeneous kinetic analysis.