Nondestructive identification of colloidal molecular sieves stabilized in water.
The encapsulation of small quaternary ammonium ions in zeolite frameworks could be used as a base for investigation of the crystallization process of colloidal (nanosized) molecular sieves stabilized in water with Raman and (13)C NMR spectroscopic methods. The organic-framework interactions in colloidal microporous materials with LTA, FAU, BEA, and MFI topology have been considered; the results show that the crystallinity of nanosized particles with monomodal particle size distribution stabilized in water can be examined using the vibrational and magnetic resonance spectral features of the organic template molecules occluded in the specific pores and cages in the zeolite framework. The molecular packing effect and restricted mobility due to specific organic/framework interactions result in shifts and substantial broadening of the (13)C NMR signals, as well as in changes of the positions and the relative intensities of the Raman peaks. The spectroscopic methods are very efficient for analyzing the crystalline structures of nanosized molecular sieves stabilized in aqueous suspensions due to no restrictions related to the particle size.
Mihailova
B
B
Department of Chemistry, University of Munich, Butenandtstrasse 11(E), D-81377 Munich, Germany.
Mintova
S
S
Karaghiosoff
K
K
Metzger
T
T
Bein
T
T