Validation of kinetic parameters based on fixed-bed experiments for hydrogen reduction of iron oxides

Reducing carbon dioxide emissions from industrial processes is a major objective of current scientific research. Iron and steel production through iron ore reduction is a key contributor to greenhouse gas emissions, which can be significantly lowered using green hydrogen. However, the process involves complex, multi-scale challenges, such as reaction kinetics, thermodynamic constraints, mass and energy transport, fluid and particle dynamics, solid morphology, and economic feasibility. Based on kinetic parameters determined on a simpler system, this work focusses on a validation of these kinetic results. Validation is achieved through experimental and modeling investigations of systems with increased complexity, using the kinetic parameters previously estimated. Experiments were carried out in a packed bed reactor-like setup using pure iron oxide powder under varied operating conditions. As a novelty in this field, the thermal conductivity measurements of the product gas were quantitatively correlated to the extent of reduction of the solid sample. A mathematical model of a fixed-bed reactor, incorporating a dynamic shrinking core model, was demonstrated to accurately reproduce the experimental findings. The results emphasize the reversible nature of the chemical reactions involved and highlight the critical influence of water vapor in the systems.