Adsorption equilibrium of xylene isomers and p-diethylbenzene on a prehydrated BaX zeolite

The present work deals with the study of adsorption equilibria of xylenes a nd p-diethylbenzene on a prehydrated BaX zeolite at 175 and 130 degreesC. T he adsorption isotherms of single components recorded by a thermogravimetri c method show that the adsorption affinity of the zeolite and the adsorbate /adsorbent interaction energy at low loading are about the same for the thr ee aromatics and that, at 175 degreesC, the adsorption capacities are the s ame for the three components. The adsorption of binary and ternary mixtures in the liquid phase has been performed by a chromatographic method. The re sults show that the selectivity depends on the composition of the liquid ph ase and on the temperature. Moreover, for the two mixtures p-xylene/m-xylen e and p-diethylbenzene/m-xylene, the effect of temperature appears only on the preferentially adsorbed component, p-xylene and p-diethylbenzene, respe ctively. Tentative interpretations in terms of adsorption sites are propose d. Last, the Langmuir-Freundlich model describes the variation of the selec tivity and the adsorbed amounts with the composition of the liquid phase in the binary mixtures. The extension of the model to ternary mixtures provid es very qualitative results.