Characterization of Cesium Sites Within Zeolites using Solid State Nuclear Magnetic Resonance

Open Access
Author:
Fleeger, Claire Rene
Graduate Program:
Chemistry
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 09, 2008
Committee Members:
  • Peter J Heaney, Dissertation Advisor
  • Karl Todd Mueller, Thesis Advisor
Keywords:
  • NMR
  • zeolites
  • cesium
Abstract:
Solid state nuclear magnetic resonance (NMR) is a technique used to characterize local cationic sites within zeolites. The primary study of this thesis applies 133Cs magic angle spinning (MAS) NMR to heulandite, merlinoite, and a faujasite/EMT intergrowth. The resulting spectra acquired from up to three different magnetic field strengths are used to calculate the quadrupole product and isotropic chemical shift for each cesium site. Since water content is a large contributing factor to cation mobility, each zeolite sample was equilibrated at 0% or 100% relative humidity to determine whether a relationship existed between the quadrupole product and relative humidity. It was found that the quadrupole product decreases as the relative humidity increases. Two solid model systems (Cs2SO4 and CsClO4) were also characterized and the same two parameters were determined. These model systems were analyzed to confirm that this method could accurately determine the isotropic chemical shift and quadrupole product. The spectral peaks from each spectrum were correlated to known cationic sites within each zeolite, providing information about site population and cesium preference. Once the positions of cesium are known, more accurate kinetic studies can be generated and sequestration of radioactive cesium can be better accomplished.