STUDIES OF HYDROGEN HELD BY SOLIDS .16. INFRARED SPECTROSCOPY OF X- AND Y-TYPE ZEOLITES CONTAINING UNIVALENT AND DIVALENT CATIONS

The IR spectra of Linde X- and Y- type zeolites, charge-balanced with different monovalent and divalent cations, were examined in the OH and NH regions after evacuation at various temperatures and when H2O or NH3 was added back. Bands near 3650 and 3545 cm-1 were identified with decationated sites. With monovalent zeolites only the former band could be detected and it resulted from hydrolysis and corresponded to the base-exchange cation deficiency. With divalent zeolites both bands appeared with the Y zeolites and at high exchange levels with the X zeolites. These bands were too strong to attribute to a deficiency of cations and it is suggested that H2O molecules are dissociated by the strong electrostatic fields of the Me2+ ions, resulting in the formation of decationated sites and ions of the type Me+-OH or Me+-O-Me+. The decationated sites reacted readily with NH3 to form NH4+. A band near 3695 cm-1 appeared when small amounts of H2O were added back. This could be attributed mainly to H2O bound to the residual Na+ ions of the preparations, but may have originated partly from a similar interaction with some of the divalent ions as well. Finally, a band near 3605 cm-1 was characterized, which could be assigned to Ca+-OH. © 1969.