Green hydrogen production via chemical looping: fuel reactor modeling with iron-based oxygen carriers

Abstract This study introduces a dynamic multiscale model for the fuel stage of a packed bed chemical looping water splitting (CLWS) system, focusing on the reduction of iron-based oxygen carriers (OC) with biogas-derived syngas. Validation against experimental data (correlation coefficients above 0.99) confirmed accurate predictions of both micro- and macroscale mass and heat transport phenomena, and reaction kinetics. Sensitivity analyses revealed that: (i) higher inflow gas temperatures significantly enhance reaction rates, (ii) moderate increases in operating pressure yield slight conversion improvements, (iii) higher flow rates improve mass transfer at the cost of increased pressure drop, (iv) smaller particle sizes determine higher conversion but further elevate pressure drop, and (v) higher particle porosity reduces mass transport limitations and promotes faster kinetics. Together with these findings, the model predicted low pressure drops underscore the feasibility of high-pressure operation and establish the packed bed CLWS technology as a competitive and scalable solution for sustainable hydrogen production. Graphical Abstract