Kinetic and Mechanistic Analysis of Methane Oxidation over Fe₂O₃/CeO₂–γAl₂O₃ Oxygen Carriers under Chemical Looping Conditions

This study investigates the reaction kinetics of Fe₂O₃/Ce-γAl₂O₃ oxygen carrier for chemical looping hydrogen production (CLHP), aiming to overcome the limited reactivity of Fe-based carriers at moderate temperatures. A comprehensive approach was employed combining temperature-programmed desorption (TPD), kinetic modeling, and experimental validation in a CREC Riser Simulator. TPD results revealed that Fe–CeγAl demonstrated the highest CO₂ desorption capacity (1.589 mmol/g), strong CH₄ retention at moderate and strong sites, and balanced CO interaction, supporting its superior gas–solid performance. Kinetic modeling of three reaction pathways (CH₄ partial and complete oxidation, and CO oxidation) yielded excellent model fitting (R² = 98.67, AIC = −106.22). The intrinsic rate constants (k₁° = 0.024, k₂° = 0.013, k₃° = 0.019) and activation energies (E₁ = 94.30, E₂ = 101.59, E₃ = 68.72 kJ/mol) confirmed that CH₄ partial oxidation is kinetically favored, while CO oxidation proceeds most rapidly for Fe–CeγAl under surface-controlled conditions in the CREC Riser Simulator. The deactivation function parameter (λ = 0.25) indicated moderate oxygen depletion, sufficient to sustain reaction efficiency up to 675 °C. This work bridges a critical gap in current CLHP research by providing a validated kinetic model and mechanistic interpretation for Ce-modified Fe₂O₃ systems. The results serve as a robust foundation for reactor design, solid circulation optimization, and predictive simulation of CLHP operations, advancing the development of low-emission hydrogen production technologies.