DIFFUSION AND REACTION IN POROUS SOLIDS: A MODEL FOR TWO DIFFERENT HETEROGENEOUS REACTIONS

We have developed a model to simulate the concentration distribution of a reacting species within an isothermal, heterogeneous, porous structure. In our model we allow for two different reactions-one at the base of a cylindrical pore and another at the pore wall. Concentration distributions have been simulated for Damköhler numbers ranging over several orders of magnitude. Closed-form solutions were obtained for first-order reactions. Concentration variations in the radial direction were calculated from a two-dimensional model; the error involved in using the one-dimensional model was quantified for a representative case. The effect of neglecting the reaction at the base of the pore was calculated for several cases pertaining to high aspect-ratio pores