Cesium-133 NMR studies of cation siting and site exchange dynamics in hydrated Cs-Na-A zeolite
Variable temperature Cs-133 NMR measurements have been made on hydrated Cs-exchanged Linde-4A zeolite containing 3.8 Cs/sup +/ ions per unit cell. At room temperature there is rapid site exchange of the Cs/sup +/ ions, so that the NMR spectrum is that of a single time-averaged environment. At temperatures below 238 K, the exchange is slowed sufficiently to permit the resolution of two resonances. These resonances can readily be assigned to Cs/sup +/ ions at 8-ring sites and 6-ring sites, which are distinguished by their large chemical shift difference of 106 ppM in the zeolite. The lifetimes and the population ratio of 2.3 for the two Cs/sup +/ ion sites are obtained by fitting the NMR lineshapes at various temperatures using a set of modified Bloch equations for a two site exchange process. An Arrhenius activation energy of 38 kJ/mol for the cationic site exchange process in A-type zeolite is obtained from the lifetimes of Cs/sup +/ ions. The rapid rate of site exchange established unequivocally that the 6-ring ion is on the ..cap alpha..-cage side of the ring. 33 refs., 2 figs., 1 tab.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6476529
- Report Number(s):
- ANL/PPRNT-89-114; ON: DE89008454
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CESIUM COMPOUNDS
ION EXCHANGE
CESIUM IONS
DIFFUSION
SODIUM COMPOUNDS
ZEOLITES
ACTIVATION ENERGY
ARRHENIUS EQUATION
CESIUM 133
CHEMICAL SHIFT
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
CESIUM ISOTOPES
CHARGED PARTICLES
ENERGY
EQUATIONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IONS
ISOTOPES
MAGNETIC RESONANCE
MATERIALS
MINERALS
NUCLEI
ODD-EVEN NUCLEI
RESONANCE
SPECTRA
STABLE ISOTOPES
400105* - Separation Procedures
400201 - Chemical & Physicochemical Properties