Modeling of pore wall amorphous structures: influence of wall heterogeneity on the mechanism of adsorption Krypton and Argon adsorption in MCM-41 pore model

Influence of the pore wall heterogeneity on the adsorption mechanism has been studied. The heterogeneity has been modeled by adsorption site distributions. Two aspects of these distributions have been analyzed: energetic and structural. It has been shown that the energy site distribution determines the low-pressure adsorption whereas the structural distribution affects the multi-layer adsorption. In the case of the adsorption of Ar atoms, one can find a distribution of adsorption sites that allows one to modify the shape of adsorption isotherms and reproduce the experimental data. In the case of Kr adsorption, we observe that the intermediate structures, between one and two layers, are not stable. (C) 2004 Elsevier B.V. All rights reserved.