Diffusional study of the reaction of sulfur dioxide with reactive porous matrices

A single-pellet high-temperature diffusion cell reactor is used to study the sulfation of calcined Greer limestone pellets. The effective diffusivities of gases through the reactive pellets, during the calcination and sulfation are determined. The experimentally determined effective diffusivity of sulfur dioxide through the pores of the product shell is used in the modified expanding grain model to obtain the diffusivity of sulfur dioxide through the product shell of the grains as a function of the conversion and the reaction temperature. The activation energy for the initial diffusivity of sulfur dioxide through the product shell of grains, is found to be 34.13 kcal mol^?1; the diffusivity values decreased with increasing conversion. Additionally it is found that the ratio of the tortuosity of reacting shell of pellet to the initial pellet tortuosity before any sulfation was increased with increasing conversion.