DEACTIVATION MODEL FOR TEXTURAL EFFECTS ON KINETICS OF GAS-SOLID NONCATALYTIC REACTIONS CHAR GASIFICATION WITH CO2

Variation of the reactivity of a solid reactant due to changes in numb er of working active sites and pore structure was represented by a dea ctivation model. The model was shown to give good aggreement with the experimental data obtained for the gasification of chars of different lignites. All the kinetic data obtained at different temperatures (800 degrees-950 degrees C) and also for different types of coals were rep resented with a single generalized relation. The increase of the surfa ce area of the char at the initial stages of gasification did not caus e a corresponding increase in the reaction rate. Results indicated tha t the surface was composed of highly reactive and less reactive sites. It was shown that the reactivity of unit surface area of the solid re actant first showed a rapid decrease due to decrease of number of more reactive sites at the initial stages and then reached to about one fo urth of its initial value.