PYRIDINE ADSORBED ON NA-FAUJASITE - A FT-RAMAN SPECTROSCOPIC STUDY

The adsorption of pyridine as a probe molecule in the characterization of Na-faujasites has been investigated with FT-Raman spectroscopy. It appears that the interaction of pyridine is strongly affected by the presence of adsorbed water within the zeolite structure. At pyridine c overages around 180 mg/g of zeolite a signal at 998 cm-1 is observed, attributed to pyridine adsorbed onto coordinated water. At higher cove rages this signal decreases, whereas a band at slightly higher wavenum ber arises due to the interaction with physisorbed water. At low cover ages an increase in wavenumber is observed, assigned to pyridine adsor ption on relatively more acidic OH sites or Na+ cations.