Xenon-129 nuclear magnetic resonance spectroscopy applied to microporous materials

Miscellaneous · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6751550

Bansal, N

The characterization of pore structure and pore properties of microporous materials such as zeolites and active carbons is crucial to understand their molecular-sieve and catalytic properties. The main theme of this research was to develop and use {sup 129}Xe NMR spectroscopy of adsorbed xenon to investigate microporous materials. {sup 129}Xe has a spin of {1/2} and relatively high natural abundance (26.4%) and its resonance frequency is very near to {sup 13}C. Xenon gas interacts only weakly with the adsorbate, but its NMR chemical shift is extremely sensitive to the nature of interaction. Its van der Waals diameter of 4.4 {angstrom} limits its sorption in very small pores and its relaxation mechanism limits its detection in meso- and macro-pores. It is therefore a sensitive probe of the environment in micropores that have window diameter more than about 4.4 {angstrom}. The chemical shift of zenon adsorbed in micropores is a sum of several terms characteristic of the various effects (such as xenon-xenon collisions, electrostatic or adsorption effects, etc.) to which it is subjected. By determining each of these terms for NiNa-Y zeolites, the information about the environment around the nickel-ions and their site preferences are obtained. The chemical shift of adsorbed xenon also depends on the amount of occluded water in zeolites. This used to probe the migration of water from one region of a sample to another region. In the case of dealuminated Y zeolite, the technique gives information about the crystallinity of a sample. The dependence of chemical shift on mean-free-path is used to characterized the pore structure in active carbon samples.

• Research Organization: Delaware Univ., Newark, DE (USA)
• OSTI ID: 6751550
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
ACTIVATED CARBON
MICROSTRUCTURE
NUCLEAR MAGNETIC RESONANCE
PERFORMANCE TESTING
POROUS MATERIALS
ZEOLITES
CATALYSTS
CHEMICAL SHIFT
CRYSTAL STRUCTURE
MOLECULAR SIEVES
POROSITY
SPIN
SURFACE PROPERTIES
XENON 129
ADSORBENTS
ANGULAR MOMENTUM
CARBON
DAYS LIVING RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
INORGANIC ION EXCHANGERS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ION EXCHANGE MATERIALS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAGNETIC RESONANCE
MATERIALS
MINERALS
NONMETALS
NUCLEI
PARTICLE PROPERTIES
RADIOISOTOPES
RESONANCE
STABLE ISOTOPES
TESTING
XENON ISOTOPES
400201* - Chemical & Physicochemical Properties
360602 - Other Materials- Structure & Phase Studies