A Multisite Microkinetic Framework for Describing Interfacial Kinetics in Dry Methane Reforming (DRM) over Ni-CeO ₂ Catalysts

Oxide-supported Ni catalysts are widely employed for the dry reforming of methane (DRM), where the metal-support interface plays a pivotal role in mediating interfacial O-transport and H-spillover reactions. In this work, a multisite microkinetic model is developed for the Ni-CeO₂ system to elucidate how interfacial processes govern the overall DRM activity and/or selectivity. Kinetic parameters for the model are obtained from density functional theory (DFT), and they are adjusted to ensure thermodynamic consistency, while geometric parameters are derived from an assumed catalyst model. Analyses of reaction orders reveal mixed dependencies of DRM rate on CH₄ and CO₂ pressures, depending on the prevailing kinetic regime. Global sensitivity analysis (Sobol) identifies the Ni nanoparticle radius (<i>r</i> _m) as a dominant geometric parameter controlling the overall rate. Degree of rate control (DRC) analysis shows that CH₄ activation is rate-determining for small Ni nanoparticles, while O-transport becomes limiting at a larger <i>r</i> _m, indicating a transition to deactivation-prone regimes. The model captures this transition without explicitly incorporating coking pathways, demonstrating its robustness in representing interfacial effects. This multisite model establishes a mechanistic framework for examining transport across metal-support boundaries and serves as a predictive tool for studying interface-mediated reaction systems.