Kinetic modeling of the oxidation of CO on Fe2O3 catalyst in excess of O2

This work addresses the oxidation of CO under oxygen-rich conditions using a Fe2O3 model catalyst. Based on in situ DRIFTS studies, isotopic labeling, and kinetic examinations performed in a gradient-free loop reactor an Eley–Rideal type mechanism is postulated. This mechanism includes the dissociative adsorption of O2 on active Fe sites, followed by reaction of surface oxygen with gaseous CO, producing CO2. Furthermore, a mean field model is constructed for numeric modeling and simulation of the CO oxidation, as well as calculation of the Fe2O3 surface coverage. The kinetic model represents a network of six elementary reactions using Arrhenius-based rate expressions. The comparison between measured and calculated data shows that the model describes the experiments well. Kinetic parameters for the elementary reactions are obtained from the literature or by fitting calculations. To reduce the number of free parameters, the patterns of O2 TPD and CO2 TPD are modeled numerically. To validate the model, the kinetic parameters are used to simulate catalytic data, which agree fairly well with the corresponding experimental results. The reaction of surface oxygen species with gas-phase CO is considered to be the rate-determining step in CO oxidation on an Fe2O3 catalyst. In addition, the thermodynamic consistency of the kinetic parameters is proven.