Molecular statistical calculation of the thermodynamic adsorption characteristics of zeolites using the atom–atom approximation. Part 2.—Adsorption of non-polar and polar inorganic molecules by zeolites of types X and Y

Abstract

Molecular statistical calculations of the thermodynamic characteristics of adsorption of Ar, Kr, Xe, O₂, N₂, CO, CO₂ and NH₃ at low (zero) filling have been carried out for X and Y zeolites. The atom–atom (atom–ion) approximation has been used to calculate the potential energy of the intermolecular interaction of non-polar monoatomic molecules of noble gases. The parameters of the potential function for the atom–ion intermolecular interaction have been improved by comparing the theoretically calculated Henry's constant for adsorption of one of the noble gases on NaX zeolite with the experimental data, as has been done previously for adsorption on graphitized thermal carbon black. The correction thus introduced into the parameters of the atom–ion potentials makes it possible to calculate not only the thermodynamic characteristics for the adsorption of different noble gas molecules on NaX zeolite, but also on other cationized zeolites of the same type, X. For polar molecules, an allowance is also made for the contribution due to the electrostatic interaction of the rigid molecular multipoles (quadrupole, dipole) with zeolite ions to the total potential energy for the intermolecular interaction with the zeolite. This contribution is calculated via the point moment approximation.