Hydrogen Iodide Decomposition Over Nickel-ceria Catalysts For Hydrogen Production In The Sulfur-iodine Cycle

摘要

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.