# A Multisite Microkinetic Framework for Describing Interfacial Kinetics in Dry Methane Reforming (DRM) over Ni-CeO2 Catalysts

## TL;DR

This paper introduces a new model to understand how reactions occur on a nickel-ceria catalyst used in converting methane and carbon dioxide into useful products.

## Contribution

A novel multisite microkinetic model is developed to describe interfacial kinetics in DRM over Ni-CeO2 catalysts.

## Key findings

- The model reveals mixed dependencies of DRM rate on CH4 and CO2 pressures based on the kinetic regime.
- Ni nanoparticle radius is identified as a key geometric parameter controlling the overall reaction rate.
- CH4 activation is rate-determining for small Ni nanoparticles, while O-transport limits larger ones.

## Abstract

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 (r
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 r
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.