Investigation of the non-isothermal water desorption on alkali-metal cation-exchanged X-type zeolites: a temperature-programmed diffuse reflection infrared Fourier transform spectroscopic (TP-DRIFTS) study

The non-isothermal desorption of water on alkali-metal cation-exchanged X-type zeolites was investigated by means of temperature-programmed diffuse reflection infrared Fourier transform spectroscopy (TP-DRIFTS). Based on the areas under the DRIFT spectra recorded at temperature intervals of 10 K, the desorption profiles could be calculated. Their shape is principally identical to the desorption curves obtained by conventional TPD (EGD/EGA). Using a numerical regularisation method, desorption energy distribution functions have been calculated. The assignment of several characteristic bands to differently bonded water molecules and explanations for certain observed trends have been given.