Abstract
Both the location and the de-trapping energy of the extraframework sodium cations embedded in Na56Y and Na96X zeolites are investigated by means of Dielectric Relaxation Spectroscopy (DRS). It is shown that the cations are distributed into three different types of crystallographic sites, with a respective occupancy established by comparing our DRS data to those previously obtained from simulation. Then, the de-trapping energy of the cations embedded in each crystallographic site is determined and analysed in the light of the structural feature of the site. The difference between the de-trapping energy of the different crystallographic sites in Na56Y and Na96X is thus interpreted using simple qualitative models based on electronegativity and cation/cation repulsion. It is thus shown that the consideration of this later parameter is essential to explain the rearrangement of the energy level of each cation site when a critical Si/Al ratio is reached.