Application of IAST in the Prediction of Multicomponent Adsorption Equilibrium of Gases in Heterogeneous Solids: Micropore Size Distribution versus Energy Distribution

Abstract

This article investigates the effect of surface heterogeneity and energy-matching scheme on the prediction of adsorption equilibria on activated carbon. The ideal adsorbed solution theory (IAST) is employed to evaluate the local adsorption equilibria on each energy site while the energetic heterogeneity of the system is represented by two forms: (1) uniform energy distribution, which employs the cumulative energy scheme to match different adsorbates in the adsorbed phase; and (2) micropore size distribution, which invokes the adsorbate-pore interaction matching scheme. The adsorption equilibria of hydrocarbon gas mixtures measured on two commercial activated carbons are used to compare the two models. It is found that uniform energy distribution can be insufficient in the prediction of multicomponent adsorption equilibria. On the other hand, the model assuming micropore size distribution as adsorption energetic heterogeneity and the adsorbate-pore interaction energy-matching scheme presents relatively stable prediction results.