Mathematical modelling of gas-solid reactions with solid product

Random pore structural models, that can be used with any type of pore size distribution, are developed for the study of gas-solid reactions with solid product under reaction conditions controlled by kinetics and diffusion in the product layer. An intraparticle diffusion and reaction model is also developed and used, along with the structural models, to study the transient behaviour of solid particles reacting under significant intraparticle diffusional limitations. Simulation results for the limestone-SO₂ system show that the transient behaviour of the reacting particles is strongly influenced by the type of the pore size distribution. Various pore structures characterized by the same values of internal surface area and porosity can lead to completely different reaction trajectories. The predictions of the mathematical models compare well with experimental data from the literature.