Dynamics of Water in Zeolite NaY(Br) Investigated by NMR

1. Introduction Zeolites are widely used in industry as molecular sieves, selective adsorbents, catalysts and ion exchangers (e.g. [1] and references therein). Therefore there is a great interest in studying the dynamics of guest molecules in such systems. Although vigorous research has been performed in the field, a complete understanding of the complex behaviour of guest molecules is still missing. We investigated water confined in a zeolite as we are also interested in the properties of different phases of bulk water and experiments in confinement may reveal more information on the matter. The zeolite NaY(Br) (Si:Al=2.43) was chosen because of its simple internal geometry and available complementary studies [2]. Its unit cell consists of eight β-cages and eight supercages. The β-cages are blocked by Br ion so that water can penetrate only in the supercages. The sample was filled with 18 molecules of water per supercage. Half of the water molecules were deuterated in order to perform 2 H NMR in addition to proton NMR.