Kinetic study of the redox process of iron oxide for hydrogen production at oxidation step

Iron oxide (Fe2O3) is a potential substitute for other materials of hydrogen storage by a redox process of Fe3O4 (initial Fe2O3) + 4H2 ↔ 3Fe + 4H2O to store and release hydrogen. In order to evaluate the effectiveness of iron oxides with Mo additive for this purpose, the behaviors of unmodified and Mo-modified Fe2O3 samples (Fe2O3-none, Fe2O3–5%Mo, Fe2O3–8%Mo and Fe2O3–10%Mo), which were prepared by hydrothermal synthesis, were investigated for hydrogen production at oxidation step. Of all the samples, Fe2O3–8%Mo was the most effective for improving H2 production at temperatures < 300 °C. The kinetic data at oxidation step obtained by isothermal experiments could be well fitted by the conventional and Jander equation. The apparent activation energy at oxidation step is about 55.53–65.30 kJ mol−1 for unmodified Fe2O3 and about 36.17–45.19 kJ mol−1 for Fe2O3–8%Mo based on the conventional and Jander models. The cooperative effect of active Fe and Mo additive on the H2O decomposition may be the main reason of lowering the activation energy.

► Fe2O3–8%Mo was the most effective for improving H2 production at temperatures <300 °C.
► The kinetic researches of the oxidation process were carried out by isothermal experiment at different operating temperatures.
► The cooperative effect of active Fe and Mo additive on the H2O decomposition may be the main reason of lowering the activation energy.