Solar thermochemical process for hydrogen production using ferrites

A two-step water splitting process using the ZnFe2O4/Zn/Fe3O4 reaction system was proposed for H-2 generation utilizing concentrated solar heat. The mixture of Zn and Fe3O4 was heated to 873 K in flowing steam with an Ar carrier gas, and the H2 gas was generated at 93.4% of the theoretical yield for the reaction of 3Zn+2Fe(3)O(4)+ 4H(2)O=3ZnFe(2)O(4)+4H(2) (H-2 generation step). The XRD and Mossbauer spectroscopy showed that the Zn-submitted ferrite (ZnxFe3-xO4; 0.2 <= x <= 1) (main solid product) and ZnO (minor) were formed in the solid products after the H-2 generation reaction. The ZnFe2O4 product, which was formed after the H-2 generation step during the two-step water splitting process with the ZnFe2O4/Zn/Fe3O4 system, could be decomposed into Zn (and ZnO) and Fe3O4 by the Xe beam irradiation at 1900 K after 3 min with a 67.8% yield for the reaction of 3ZnFe(2)O(4) = 3Zn + 2Fe(3)O(4) + 2O(2) (O-2 releasing step = solar thermal step). (c) 2004 Elsevier Ltd. All rights reserved.