Hydrogen iodide decomposition over nickel–ceria catalysts for hydrogen production in the sulfur–iodine cycle

Abstract

In this work, pure CeO 2 and three nickel–ceria catalysts prepared by different methods have been tested to evaluate their effect on hydrogen iodide (HI) decomposition in the sulfur–iodine (SI or IS) cycle at various temperatures. BET, XRD, HRTEM and TPR were performed for catalysts characterization. Indeed, the pure CeO 2 also strongly enhance the decomposition of HI to H 2 by comparison with blank yield. Nickel–ceria catalysts show better catalytic activity, especially Ni-doping-G sample. It is found that, through the sol-gel method, the Ni 2+ ions have dissolved into the ceria lattice instead of the Ce 4+ ions during the synthesis process of Ni-doping-G sample. Oxygen vacancies are formed because of the charge imbalance and lattice distortion in CeO 2. The presence of Ni during the CeO 2 synthesis process of Ni-doping-G also causes smaller average particle size, larger surface area, better thermal stability and better Ni dispersion than the Ni-loading samples. These provide nickel–ceria catalyst with a potential to be used in the SI cycle for HI decomposition.