Overview of the development of catalysts for HI decomposition in the iodine–sulfur thermochemical cycle at INET

The decomposition of HI which is the key reaction to produce hydrogen in the iodine–sulfur thermochemical cycle takes place hardly without the catalysts even at 500 °C. Therefore, the catalysts play very important role during the HI decomposition. At INET, fundamental studies on the HI catalytic decomposition were initiated in 2006. This paper summarized our present research advances on the development of HI decomposition catalysts containing different supports (carbon nanotubes, active carbon, carbon molecular sieve, graphite and γ-Al2O3), supported monometallic (Pt, Ir and Ru) and bimetallic (Pt–Ir), and the preparation methods including impregnation-H2 reduction, impregnation–calcination, impregnation-hydrazine reduction, and electroless plating. In the course of the study, the physical properties, structure, and morphology of the catalysts were characterized by specific surface area (BET), X-ray diffractometer (XRD), and transmission electron microscopy (TEM), respectively. The catalytic activity for HI decomposition was investigated in a fixed bed reactor under atmospheric pressure. In addition, choice of catalysts for the future IS cycle was discussed.