EFFECT OF THE CATION MOBILITY ON THE X-RAY-DIFFRACTION PATTERN AND THE SI MAS NMR-SPECTRA OF NA,COY ZEOLITES

The paramagnetic Co2+ cations in partially exchanged CoNaY occupy site s I' and II' where their mobility is strongly restricted. The NMR reso nance line of Si immediately adjacent to these sites disappears by bro adening. The mobile Co2+ cation influences the residual Si resonance l ines differently, in that it decreases the intensity of the Si resonan ce in the (4)Q(2Al) and (4)Q(3Al) environments. The modification of th e scattering factor at the sites where cobalt is not mobile provokes s trong intensity modifications in the X-ray reflections. The relative m obile and nonmobile cobalt amount in the Na-Co exchange is quantitativ ely related. (C) 1998 Elsevier Science B.V. All rights reserved.