Application of the zone model to multiple noncatalytic fluid-solid reactions

Abstract

The effect of intraparticle diffusion on the multiple gas-solid reactions occurring in a porous solid reactant is analyzed by the zone reaction model. In parallel reactions for gases and a consecutive reaction for the solid, the solutions of transient concentration profiles of two solid reactants are given by classifying three zones, viz. Reaction zone and reaction-diffusion zone and diffusion zone in the course of the reaction progression. As an example, the simultaneous reduction-sulfidation of porous iron oxide sorbent in the desuifurization from low BTU coal gases is analyzed by the present model. The Thiele modulus of the reaction governs the behavior of the moving boundary between the reaction zone and the diffusion zone. When the Thiele modulus tends to be infinite, the present model is consistent with the solutions based on the unreacted shrinking core model.