Investigation of multi-component liquid adsorption of alkylaromatics in NaX zeolite using novel gas chromatographic headspace techniques

Abstract

In this study, adsorption isotherms of o-xylene, ethylbenzene and toluene liquid solutions on a commercial 13X zeolite adsorbent were measured using the gas chromatographic headspace technique. According to this technique, the vapor, in equilibrium with the liquid phase and solid adsorbent, is analyzed using a GC column. In the first part of the study, a novel technique was introduced based on liquid calibration curve procedure. In addition, the earlier introduced vapor calibration technique was further extended to measure single component isotherms of non-ideal liquid solutions. In this part of the study, both vapor and liquid calibration techniques were extended to measure liquid adsorption isotherms of the multi-component solutions involving both, ideal solutions e.g., aromatic sorbates, and non-ideal solutions, e.g., aromatic sorbates and n-decane as a solvent. Consequently, Raoult's law and extended Raoult's vapor-liquid equilibrium (VLE) law for calculations of ideal and non-ideal solutions were applied, respectively. Extended Wilson and NRTL models were used to determine the sorbates' activity coefficients in the non-ideal liquid solutions. The multicomponent isotherms involving both ideal and non-ideal liquid solutions were experimentally determined at 30, 60 and 90 °C and also predicted by the extended Sips adsorption model. Based on these results, the selectivity of the NaX zeolite towards different sorbates from the selected mixtures were determined at different temperatures and concentrations.