Microscopic behavior and metallic iron morphology from reduction of iron oxide by CO/H2in a fluidized bed

Abstract

Fe2O3particles reduced by CO or H2exhibit different metallic iron morphology. To determine the mechanism of metallic iron formation during the reduction of iron oxide particles by CO/H2in a fluidized bed, an innovative multiscale method was used. This method was validated by experimental results. Density functional theory calculations demonstrate that the CO molecule has a strong stretching effect on the iron ion of wustite in the vertical direction, but the H2molecule has no directional force on the structure of wustite. The energy released from CO reduction is used to overcome the energy barrier of iron ion diffusion. However, H2addition will hinder iron ion diffusion by consuming energy. By analysis of the thermogravimetric curves of Fe2O3reduction, it was found that the adsorption ability of H2on the surface of FeO is weaker than that of CO. However, the reduction rate is higher under H2atmosphere, according to Langmuir adsorption isotherm theory. The morphology of metallic iron during the reduction of iron oxide particles by CO/H2was observed with a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy detector