Multicomponent adsorption on zeolites and state of adsorbed phase

An approach based on statistical thermodynamics is developed for mixed gas adsorption. The model takes into account energetic heterogeneity of zeolite and molecular rearrangement in a cavity, which leads to decrease of internal energy and entropy of mixtures. The information of the heterogeneity of the adsorption field in a cavity is evaluated from pure component isotherms. The approach allows predicting selectivity and total amount adsorbed without any empirical parameters. It is shown that all experimental points are to be in the range restricted by two curves, which correspond to ideal mixture and to the limiting case of non-ideal mixture, respectively. The model has been confirmed by analysis of highly non-ideal systems oxygen - nitrogen and oxygen - carbon monoxide - zeolite 10X at 144 K.