Adsorption of a Multicomponent Mixture of Gases with Multisite Occupancy

Abstract

In this paper, we present a study of the adsorption of multicomponent mixtures with multisite occupancy. The transfer-matrix technique is used to analyze the one-dimensional binary mixtures for interacting systems. A general expression for the characteristic polynomial is derived. Extension of the treatment to a higher dimension is also presented by using the mean-field Bragg-Williams approximation, transfer-matrix calculations, and Monte Carlo simulation. Partial and total isotherms are obtained for the dimer-trimer mixture where a different order appears.

Adsorption–desorption kinetics of the monomer–dimer mixture

“…The last expressions are in complete agreement with the transfer matrix results reported in Reference [22]. In the presence of nearest neighbor lateral interaction only a numerical solution can be obtained.…”

“…2(b), we show the isotherms corresponding to 11 = 12 = 0 and different values of 22 . As expected, the initial coverage for dimers depends on the lateral interaction values.…”

“…Graphical representation of the adsorbate-adsorbate interactions, i.e., monomer-monomer: 11 , monomer-dimer:12 and dimer-dimer:22 .…”

Quasi-chemical approximation for polyatomic mixtures

“…For the one-dimensional lattice, the problem of interacting mixtures with multisite occupancy can be exactly solved and there is no evidence of phase transitions. 30 Close approximate solutions in dimensions higher than one can be obtained, and the two most important of these are the Bragg-Williams approximation (BWA) 31 and the quasi-chemical approximation (QCA). 31 By following this line of reasoning, in Ref.…”

“…(2) to reproduce the classical QCA for a binary mixture of monomers 1 and the exact statistical thermodynamics of interacting mixtures adsorbed in one dimension; 30 (3) to develop an accurate approximation for two-dimensional adlayers accounting for non-ideal gas mixtures and multisite occupancy; and (4) to provide a simple model from which experiments may be interpreted.…”