Adsorption of water in zeolite sodium-faujasite - A molecular simulation study

We report a molecular simulation study of water adsorption in model NaY and NaX faujasite. Despite the rather simple model used for the water-adsorbent interaction, a fair agreement was found with the available experimental data. In the method used in this work the nonframework cations are allowed to move from place to place in the sample, and are not fixed anymore in their crystallographic sites, as in most of the previous adsorption simulations reported in the literature. We have indeed observed a cation redistribution upon water adsorption in a low cation content faujasite (Na48Y), but no such cation redistribution was observed in the higher cation content Na76X faujasite. The water adsorption process can thus be very different, depending on the Si/Al ratio of the alummosilicate faujasite. (c) 2005 Academie des sciences. Published by Elsevier SAS. All rights reserved.