Solar thermochemical process for hydrogen production using ferrites

• Published in: Energy (Oxford) Vol. 30; no. 11; pp. 2171 - 2178
• Main Authors: Kaneko, Hiroshi, Gokon, Nobuyuki, Hasegawa, Noriko, Tamaura, Yutaka
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-2005; Elsevier Science
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Energy; Exact sciences and technology; Fuels; Hydrogen; Water; Thermochemical processes; Zinc Iron Oxides; Ferrite; Iron oxide; Solar energy; Moessbauer spectrometry; X ray diffractometry; Water vapor; Mixture; Hydrogen production; Zinc
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2004.08.020

A two-step water splitting process using the ZnFe
2O
4/Zn/Fe
3O
4 reaction system was proposed for H
2 generation utilizing concentrated solar heat. The mixture of Zn and Fe
3O
4 was heated to 873
K in flowing steam with an Ar carrier gas, and the H
2 gas was generated at 93.4% of the theoretical yield for the reaction of 3Zn+2Fe
3O
4+4H
2O=3ZnFe
2O
4+4H
2 (H
2 generation step). The XRD and Mössbauer spectroscopy showed that the Zn‐submitted ferrite (Zn
x
Fe
3−
x
O
4; 0.2≤
x≤1) (main solid product) and ZnO (minor) were formed in the solid products after the H
2 generation reaction. The ZnFe
2O
4 product, which was formed after the H
2 generation step during the two-step water splitting process with the ZnFe
2O
4/Zn/Fe
3O
4 system, could be decomposed into Zn (and ZnO) and Fe
3O
4 by the Xe beam irradiation at 1900
K after 3
min with a 67.8% yield for the reaction of 3ZnFe
2O
4=3Zn+2Fe
3O
4+2O
2 (O
2 releasing step=solar thermal step).