Adsorption of water and aromatics in faujasite zeolites: a molecular simulation study

We report a molecular simulation study of the equilibrium adsorption of water and aromatics in zeolite faujasite NaY The Monte Carlo simulation methodology used in this work allows the nonframework cations to redistribute upon adsorption of fluids. We indeed observe a cation redistribution in model NaY upon water adsorption. The same phenomenon is observed in presence of adsorbed xylene molecules in the framework. A very small amount of water (some 5% weight) leads to the observed cation redistribution. The consequence of this is a change by a factor of 4 in the adsorption selectivity of NaY in favor of p-xylene, when a mixture of m and p-xylene are exposed to the zeolite sample.