Hydrogen Production by Using Redox Cycle Reaction of Foreign Oxide Coated Iron Oxide

Abstract

The hydrogen energy society is desirable to mitigate global warming. The redox cycle reaction of iron oxide Fe₃O₄ which can generate 4.8 mass% hydrogen is considered as one of means to storage and supply it. However, this reaction is known to be significantly retarded due to sintering iron oxide or iron particles. In this work, influence of foreign oxides coating on the surface of iron oxide fines is examined to improve the reaction efficiency.
Al₂O₃ coating enhanced the reaction efficiency until 97% even for more redox reaction cycles which is superior to SiO₂ coating, probably because of difference of gas diffusivity through coating layers.
Redox reaction rates in this work were nearly one order of magnitude larger than previous ones, which were obtained with samples prepared by coprecipitation from solution containing additives.
The activation energy for reduction of Al₂O₃ coating samples was obtained 41.2 kJ/mol close to that in a literature.