A structural model for gas solid reactions with a moving boundary—VI: The effect of grain size distribution on the conversion of porous solids

Abstract

A distributed model is proposed for a first order, irreversible reaction between a porous solid and a gas in which allowance is made for a grain size distribution in the reactant solid matrix. By using approximate algebraic relationships between conversion and time, adopted from the grain model, solutions were generated for various types of grain size distribution. It was found that in general the plots of conversion against time for a grain size distribution differed from those computed for a single mean grain size. Only for closely sized grains or for a log normal grain size distribution was this difference relatively small. Thus the effect of grain size distribution is thought to be of importance in both the interpretation of experimental data in terms of the grain model and in procedures used for deducing kinetic parameters from experimental measurements.