A comprehensive kinetic model for the CO-CO2 reaction with iron oxide-containing slags

A comprehensive kinetic model has been developed that enables the rate of the CO-CO2 reaction with FeOx-containing slags to be predicted. The model was developed considering a reaction mechanism involving adsorption of CO2 at the surface, charge transfer to the adsorbed CO2, and, finally, dissociation of CO2−. The rate-determining step of the reaction was found to be the formation of the CO2− ion, with the activation energy required to transfer charge to the CO2 being dependent on slag composition. The model in its simplest form relates the apparent rate constant to temperature with an Arrhenius-type correlation, whereas both the pre-exponential and activation-energy terms are functions of slag chemistry. The model resolves the complexity previously reported in the mechanism and kinetics of the reaction and provides a self-consistent explanation for all reported observations. Comparison of calculated and measured rate constants shows that there is a good fit between the two, and the rate expression can be applied successfully for the rate-constant calculations.