Cesium-133 NMR studies of cation siting and site exchange dynamics in hydrated CsNa-A zeolite

Journal Article · Thu Jun 15 00:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100349a049· OSTI ID:6831510

Ahn, M K ^[1]; Iton, L E ^[2]

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1. Indiana State Univ., Terre Haute (USA)
2. 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-31-109-ENG-38
• OSTI ID: 6831510
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 93:12; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ZEOLITES
NUCLEAR MAGNETIC RESONANCE
CESIUM 133
LOW TEMPERATURE
SITE CHARACTERIZATION
ALKALI METAL ISOTOPES
CESIUM ISOTOPES
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
MAGNETIC RESONANCE
MATERIALS
MINERALS
NUCLEI
ODD-EVEN NUCLEI
RESONANCE
STABLE ISOTOPES
360100* - Metals & Alloys
360104 - Metals & Alloys- Physical Properties
400201 - Chemical & Physicochemical Properties