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

Abstract

A comprehensive kinetic model has been developed that enables the rate of the CO-CO 2 reaction with FeO x -containing slags to be predicted. The model was developed considering a reaction mechanism involving adsorption of CO 2 at the surface, charge transfer to the adsorbed CO 2 , and, finally, dissociation of . The rate-determining step of the reaction was found to be the formation of the ion, with the activation energy required to transfer charge to the CO 2 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.

Effect of Applied Voltage on Electroreduction with Controlled Oxygen Flow of Molten Slag Containing FeO at 1723 K

“…48,58,59) It is inferred that slag penetration into the zirconia membrane and the phase transformation with an increase of the monoclinic phase amount can induce an increase of electronic conductivity of the zirconia membrane. Thus the external current (I ex ) is actually the sum of the pure oxygen ionic current ( I O 2−) and the internal electronic current (I e ) passing directly through the MSZ membrane as shown in Fig.…”

Interfacial Rate of CO2^|^ndash;CO Reaction with the Solid Iron and Iron Oxide by Isotope Exchange Technique at 1273 K

“…20) To explain the relationship between rate constant and CO 2 /CO ratio, Grabke 1,2) proposed a theory of defect structure according to the electron transfer mechanism for the CO 2 reaction with iron oxide. However, it is difficult to accurately describe the interfacial kinetics because the defect structure of iron oxide such as wüstite and magnetite is much more complicated than assumed by Grabke. According to the usual understanding, CO 2 dissociation on the surface of metal and oxides containing iron oxide can be expressed as follows: If the electron can be considered as a chemical entity, 25) the rate of CO 2 dissociation will be expressed as Eq. (9) and the apparent rate constant will be given by Eq.…”

Relationship between Electronic Conductivity of Iron Oxide–Containing Slags and Reaction Kinetics with CO-CO2

“…The purpose of this article is to discuss the relationship, or lack thereof, between the electronic conductivity of iron oxide-containing slags and their catalytic behavior in reaction with gases. This work was originally undertaken as a gas-slag reaction study, [1,4] which, in common with previous work by the others, [5,6] indicated a mechanism involving free electrons at the surface of the slag (i.e., Reactions [3] and [4]). As a way to probe this mechanism further, the electronic conductivities of several slags were measured and reported.…”

“…A comprehensive model has recently been proposed by the authors [1] to present the reaction rate based on a multistep reaction mechanism as follows:…”