Adsorption of water on ZSM-5 zeolites

The non-isothermal desorption of water adsorbed on ZSM-5 zeolites at room temperature shows, depending on the cation type (H+, Na+), differently structured desorption curves. A kinetic analysis based on various methods shows that the course of desorption is well described by a first order rate equation considering a distribution function for the desorption energy. In addition, adsorption isotherms were measured at room temperature. The adsorption energy distribution functions calculated with a regularization method can be correlated with the desorption energy distributions, FTIR investigations of water-loaded zeolites enables the assignment of desorption steps to different adsorbate complexes.