We have investigated the interaction of water with Na+-ion exchanged zeolites of different structures (LTA, FAU, ERI, MOR and MFI) by means of temperature-programmed desorption
(TPD). The non-isothermal desorption of water shows, depending on the zeolite type, differently structured desorption profiles.
In every case the profiles have, however, two main ranges. Using a regularization method, desorption energy distribution functions
have been calculated. The desorption energy distributions between 42–60 kJ mol−1, which can be attributed to a non-specific interaction of water, show two clearly distinguished energy ranges. The water
desorption behaviour of this range correlates with the electronegativity of the zeolites and the average charge of the lattice
oxygen atoms calculated by means of the electronegativity equalization method (EEM). The part of the desorption energy distributions
in the range of 60–90 kJ mol−1, reflecting interactions of water with Na+ cations, shows two more or less pronounced maxima. In agreement with vibrational spectroscopic studies in the far infrared
region, it may be concluded that all samples under study possess at least two different cation sites.