Preparation and Activities of Iridium Catalysts Supported on Thermostable Alumina for the Decomposition of Hydrazine

Various AI2O2-supported iridium catalysts for the decomposition of hydrazine were prepared by using the thermostable alumina synthesized by an improved sol gel method. The thermal stability of the catalysts was evaluated by comparison of the catalytic activities before and after thermal treatments at high temperatures (750-850°C) in an inert gas atmosphere. It was found that the performances of the Ir/Al203 catalysts using the thermostable alumina were better than those of the Ir/Al2O3 catalysts using commercial alumina. The performances and the deterioration of the Ir/Al2O3 catalysts strongly depended on the solvents used at the Ir impregnation step: C2H5OH was better suited for the catalyst preparation than CH3CN and H2O. C2H5OH solvent gave finer dispersion of iridium on the catalysts after aging than CH3CN. XPS analyses showed that C2H5OH tended to have a larger amount of iridium deposited on the surface region of catalysts than H2O.