Reactive Working Material for Use in Hydrogen Production by Decompostion of Water

Abstract

Disclosed is a reactive working material for use in a process of producing hydrogen by splitting water based on a two-step thermochemical water-splitting cycle through the utilization of solar heat, industrial waste heat or the like, which comprises a ferrite fine powder and a cubic zirconia supporting the ferrite fine powder. This reactive working material makes it possible to prevent scaling off of the ferrite fine powder from the zirconia fine powder due to volumetric changes of the ferrite fine powder during repeated use, and suppress growth of FeO grains due to repetition of melting and solidification when used as a reactive working material for a cyclic reaction under a high temperature of 1400° C. or more.

Description

TECHNICAL FIELD [0001] The present invention relates to a technique of producing hydrogen by splitting water through the utilization of solar heat, industrial waste heat or the like, and more particularly to a hydrogen production process based on a two-step thermochemical water-splitting cycle and a reactive working material for use in the hydrogen production process. BACKGROUND ART [0002] A hydrogen production process based on a two-step thermochemical water-splitting cycle has been widely known before the filing of this patent application. The hydrogen production process is designed to repeat the following two reaction formulas. MOox→MOred+½O2   First Step MOred+H2O→MOox+H2   Second Step [0003] Specifically, this hydrogen production process comprises a first step of reducing a metal oxide MOox to form a reduced metal oxide MOred and produce oxygen through a high-temperature thermal decomposition reaction, and a second step of reacting the reduced metal oxide with water to oxidize ...

AI Technical Summary

Benefits of technology

[0009] In a reactive working material for use in a hydrogen production process based on a two-step thermochemical water-splitting cycle, which comprises ferrite and zirconia supporting the ferrite, it is an object of the present invention to provide an effective means for preventing the ferrite from scaling off the zirconia due to volumetric changes of the ferrite during repeated use.

[0010] It is another object of the present invention to provide a means for suppressing growth of FeO grains due to repetition of melting and solidification when used as a reactive working material for a cyclical reaction under a high temperature of 1400° C. or more.

Problems solved by technology

Therefore, it is required to quench the vaporized substance, and this requirement makes it difficult to put the two-step thermochemical water-splitting cycle to practical use.

Thus, due to volumetric changes of these powders during the reaction cycle, the ferrite fine powder will scale off from the zirconia fine powder to spoil the zirconia powder's effect of suppressing grain growth in the ferrite fine powder., Moreover, under a reaction atmosphere repeatedly having a temperature of 1400° C. or more which is greater than a melting point of FeO, the ferrite fine powder will be gradually agglomerated to cause grain growth while repeating melting and solidification, resulting in deterioration of reaction efficiency.

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