Thermochemical hydrogen production by a redox system of ZrO_2-supported Co(II)-ferrite

摘要

The thermochemical two-step water splitting was examined on ZrO_2-supported Co(II)-ferrites below 1400℃, for purpose of converting solar high-temperature heat to clean hydrogen energy as storage and transport of solar energy. The ferrite on the ZrO_2-support was thermally decomposed to the reduced phase of wustite at 1400℃ under an inert atmosphere. The reduced phase was reoxidized with steam on the ZrO_2-support to generate hydrogen below 1000℃ in a separate step. The ZrO_2-supporting alleviated the high-temperature sintering of iron oxide. As the results, the ZrO_2-supported ferrite realized a greater reactivity and a better repeatability of the cyclic water splitting than the conventional unsupported ferrites. The Co_xFe_(3-x)O_4/ZrO_2 with the x value of around 0.4-0.7 was found to be the promising working material for the two-step water splitting when thermally reduced at 1400℃ under an inert atmosphere.