Kinetic Modeling of CO₂and H₂O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy Model

A distributed activation energy model (DAEM) was applied to the kinetic analysis of CO2 and H2O gasification reactions for pulverized metallurgical coke. The results of the scanning electron microscopy observations and CO2 gas adsorption suggested that the gasification reaction occurs at the particle surface. Therefore, a grain model was employed as a gasification reaction model. The reaction rates of CO2 and H2O gasification were evaluated based on the DAEM. The activation energy changed as the reaction progressed and hardly depended on the particle size. The activation energies were 200-260 kJ/mol in CO2 gasification and 220-290 kJ/mol in H2O gasification. The frequency factor of H2O gasification was approximately 10 times larger than that of CO2 gasification, regardless of the progress of the reaction. At the same activation energy level, the frequency factor showed a higher value with a decrease in the particle size. This result was consistent with the theory of the grain model and indicated that the gasification reaction of the pulverized coke with a micrometer scale occurs on the surface of the coke particle. Furthermore, the value predicted by the DAEM was in good agreement with the experimental one.