Cesium-133 NMR studies of cation siting and site exchange dynamics in hydrated CsNa-A zeolite
- Indiana State Univ., Terre Haute (USA)
- Argonne National Lab., IL (USA)
Variable-temperature cesium-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 eight-ring sites and six-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 line shapes 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 zeolites is obtained from the lifetimes of Cs{sup +} ions. The rapid rate of site exchange establishes unequivocally that the six-ring site ion is on the {alpha}-cage side of the ring.
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6831510
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:12; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360100* -- Metals & Alloys
360104 -- Metals & Alloys-- Physical Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALKALI METAL ISOTOPES
CESIUM 133
CESIUM ISOTOPES
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
LOW TEMPERATURE
MAGNETIC RESONANCE
MATERIALS
MINERALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
RESONANCE
SITE CHARACTERIZATION
STABLE ISOTOPES
ZEOLITES