Evaluation of hydrogen generation test using redox reaction

Abstract

The hydrogen energy society is desirable to mitigate global warming. The redox reaction of iron oxide Fe3O4 which can generate 4·8 wt% hydrogen for metallic iron is considered as one of means to store and supply it. However, this reaction is known to be significantly retarded because of sintering of solid particles. Toward solving these problems, our previous research proved alumina coating on the surface of fine iron oxide particles could improve the reaction efficiency most drastically. In this work, a lot of small pellets made of 1·25 mol% alumina coating fine particles Fe2O3 (0·1 μm dia.) by means of hydrometallurgy were prepared. Then, hydrogen generation using redox reaction in the packed bed of these pellets was tested under electric heating by gas chromatography of exit gas. Based on steam conversion degrees at 350°C with oxidation time after H2 reduction at 500°C, it was found that less steam flow rates in H2O-N2 oxidizing gas mixture (a constant N2 flow rate) provided higher steam conversion degrees near 100% and the theoretical total hydrogen generation degrees were mostly realized, independently of steam flow rates. The results were overall investigated with the view point of potential application to fuel cell.