Reaction kinetics of reduction and oxidation of metal oxides for hydrogen production

Abstract

Partial oxidation of methane and water splitting for hydrogen production were carried out. The reaction kinetics of reduction and oxidation (redox) of Mn and Zn iron oxides were determined using a thermogravimetric analyzer. The reduction conversion of the metal oxides increases with temperature above 1073 K and all the experimental data are well represented by the diffusion-limited mechanism except ZnFe(2)O(4) due to the solid state diffusion of iron and the reaction with solid carbon. The oxidation reaction was also controlled by the product-layer diffusion mechanism. Substitution of Mn and Zn cations with iron oxides can lower the reaction temperature and increase the reaction rate. The reaction rate and the activation energy (57-110 kJ/mol) for decomposition of water by oxidation of the metal oxides were also determined. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.