A cluster-exact approximation study of the adsorption of binary mixtures on heterogeneous surfaces

Abstract

The adsorption of binary mixtures on heterogeneous surfaces is studied by a cluster approximation (CA), based on the exact calculation of configurations on finite cells. The substrate is characterized by n types of sites, each with different adsorption energy. The process is monitored through the total and partial isotherms. The theoretical formalism is used to model experimental data of methane–ethane mixtures adsorbed on a template-synthesized carbon. The CA results are compared with the ones corresponding to the well-known Ideal Adsorbed Solution Theory (IAST). Even though a good fitting is obtained from IAST, it is found that CA is a more accurate model to estimate the binary data on the highly heterogeneous carbon sample.