Adsorption Equilibrium of Xylene Isomers and <i>p</i>-Diethylbenzene on a Prehydrated BaX Zeolite

Abstract

The present work deals with the study of adsorption equilibria of xylenes and p-diethylbenzene on a prehydrated BaX zeolite at 175 and 130 °C. The adsorption isotherms of single components recorded by a thermogravimetric method show that the adsorption affinity of the zeolite and the adsorbate/adsorbent interaction energy at low loading are about the same for the three aromatics and that, at 175 °C, the adsorption capacities are the same for the three components. The adsorption of binary and ternary mixtures in the liquid phase has been performed by a chromatographic method. The results show that the selectivity depends on the composition of the liquid phase and on the temperature. Moreover, for the two mixtures p-xylene/m-xylene and p-diethylbenzene/m-xylene, the effect of temperature appears only on the preferentially adsorbed component, p-xylene and p-diethylbenzene, respectively. Tentative interpretations in terms of adsorption sites are proposed. Last, the Langmuir−Freundlich model describes the variation of the selectivity and the adsorbed amounts with the composition of the liquid phase in the binary mixtures. The extension of the model to ternary mixtures provides very qualitative results.