N. Yasyerli et al., DEACTIVATION MODEL FOR TEXTURAL EFFECTS ON KINETICS OF GAS-SOLID NONCATALYTIC REACTIONS CHAR GASIFICATION WITH CO2, Chemical Engineering Science, 51(11), 1996, pp. 2523-2528
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.