Molecular modelling of adsorption of gas mixtures in montmorillonites intercalated with Al13-complex pillars

A new molecular model of montmorillonites, which are intercalated with pillars, is developed. The model is based on recent data on transmission electron microscopy, powder X-ray diffraction and energy dispersive X-ray spectroscopy, reported for these materials. The model is then used to generate the adsorption isotherms for CO2, CH4 and N2, and their ternary mixtures, using equilibrium molecular dynamics simulations. A semi-empirical statistical mechanical theory of adsorption, developed previously by the authors, is employed to correlate the results of the molecular simulations. The theory is shown to provide very accurate fits of the simulation results. In addition, the parameters of the theory can be estimated from pure component adsorption data. The performance of the theory is also compared with that of another theory of adsorption based on a virial expansion.