Structure-resolved numerical simulations of chemical-looping steam methane reforming on Cerium oxides supported perovskite-type oxygen carriers

• A structure-resolved numerical model was developed to capture transient redox behavior in the CL-SMR process. • Oxygen carrier configurations affected the flow design, heat/mass transfer and reaction-heat response. • Stagewise reaction mechanisms were elucidated using Sestak-Berggren kinetics. • Monolithic structure minimizes conversion and temperature variations, enabling precise control of reaction extent. Chemical-looping steam methane reforming is a promising technology for co-producing syngas and hydrogen with high energy efficiency and tunable product compositions for downstream applications. The process relies on oxygen carriers with redox activity, whose structural design critically impacts dynamic reaction performance. Using a structure-resolved numerical simulation model, this study investigated the performance of oxygen carriers with spherical, cylindrical, 4-hole pellet, and monolithic structures. Systematic analyses of reaction behavior and heat and mass transfer characteristics were conducted during reduction and oxidation processes. The results suggested that monolithic structures demonstrated the highest flow resistance but the lowest variations in conversion and temperature, ensuring stable and uniform control of reaction extent in the cyclic process. Cylindrical structures mitigated thermal shocks due to their high solid mass fraction. However, cylindrical and 4-hole pellet structures suffered from stagnant flow zones within gaps and channels, reducing heat/mass transfer efficiency. Monolithic structures achieved superior heat transfer coefficients with a rapid reaction-to-heat transfer response, owing to optimized mass transfer and low thermal inertia. Notably, they were minimally affected by operational fluctuations, thereby indicating robust performance across reaction stages. These findings provide critical insights into the structural design of oxygen carriers, enhancing both process efficiency and reaction controllability.