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Abstract: Effects of CeO2 additive to Fe-based mixed oxide mediums with Rh and ZrO2 for chemical hydrogen storage were investigated in terms of stability and reactivity of the mediums in water splitting oxidation with repeated redox cycles. The mediums with CeO2 content ranging from 0 to 30wt% were prepared by co-precipitation method using urea solution as a precipitant. The hydrogen storage and release properties were investigated during repeated isothermal redox cycles at 823K for reduction with hydrogen and 623K for oxidation with water vapor under atmospheric pressure. The amount of hydrogen produced by the mediums, both with and without CeO2, was maintained at an almost constant level over ten repeated redox cycles. However, the oxidation rates of the mediums without CeO2 were decreased during repeated redox cycles while that increased with increasing CeO2 contents. Especially, the mediums added with 30wt% of CeO2 (FRZC-30) showed high activity and stability for ten redox cycles, the degree of hydrogen storage was almost maintained ca. 1.9wt% on the basis of total amount of the medium. [Copyright &y& Elsevier]

Abstract: Methane was reformed over a Cu-ferrite/ZrO2 medium in a two-step process, consisting of a syn-gas production step and a water-splitting step. In the syn-gas production step, increase in Cu content in the Cu x Fe3−x O4/ZrO2 medium suppressed carbon deposition and enhanced the reaction rate for stoichiometries of x ≤0.7. In the water-splitting step, the addition of Cu promoted the gasification of the deposited carbon. Furthermore, the addition of Ce as a binder in the Cu0.7Fe2.3O4/Ce–ZrO2 medium also improved reactivity in the syn-gas production step and yielded the highest reactivity when the molar ratio of Ce/Zr was 3/1. As a result of the co-addition of Cu and Ce, the Cu0.7Fe2.3O4/Ce–ZrO2 medium showed high durability, with a constant evolution of the synthesis gas and hydrogen in ten repeated cycles. It is thus expected that the Cu-ferrite/Ce–ZrO2 medium is favourable for two-step methane reforming. [Copyright &y& Elsevier]