Dielectric relaxation spectroscopy: The location and de-trapping energy of extra-framework cations in zeolites

Abstract

This proceeding reports dielectic relaxation results, by means of Complex Impedance Spectroscopy and Thermally Stimulated Current measurements, obtained for mordenites frameworks. Most of these data has been already published but it is the first time that they are compiled. Our purpose is to demonstrate that dielectric relaxation spectroscopy can be a powerful tool for investigating the influence on ion dynamics of i) the nature of the extra-framework cation ii) the exchange rate iii) the acidity (Si/Al ratio) of the polyanionic framework iv) the number of adsorbed molecules (water, methanol heptane…). Both location and de-trapping energies of extra-framework cations in mordenites extracted from the dielectric response of these zeolites are then compared and analysed in the light of i) X-Ray diffraction data collected in literature and of ii) atomistic simulations based on classical interatomic. The later alculations are found to be in good agreement with the experimental data.