Synthesis and application of mesoporous gamma alumina granules as iridium catalyst support

Mesoporous gamma-alumina granules, which are known as a common catalyst support in industrial applications were synthesized via the sol gel-oil drop method having a diameter of 1-2 mm. The effect of calcination temperature (450 and 750 °C) on the properties of gamma alumina granules were studied and the functionality of 20 wt% iridium catalyst on the alumina granules for hydrazine decomposition was evaluated. The presence of gamma-alumina as the only constituent phase up to 750 °C was revealed by XRD analysis. According to N2 adsorption-desorption analysis, the specific surface area of gamma alumina granules calcined at 450 and 750 °C was 303.05 and 227 m2/g, respectively. HR-TEM analysis was used to investigate the granules’ morphology, and the capability of the granules as a support for iridium catalyst was evaluated during the hydrazine decomposition test. Using alumina granules calcined at 750 °C as the catalyst support, the hydrogen selectivity reached 22% and the decomposition rate was 235 h-1, and the granules’ crushing level was as low as 7% during the test, indicating that the granules have an acceptable surface area, pores diameter, and interconnectivity.