Journal of Physical Chemistry B, Vol.101, No.42, 8418-8437, 1997
Anisotropic Xe Chemical-Shifts in Zeolites - The Role of Intracrystallite and Intercrystallite Diffusion
We provide observations and interpretations of Xe-129 chemical shifts in open zeolite networks in which the Xe is in fast exchange among a large number of cavities and channels, in two zeolite types different from the A types that we have used before, and provide quantitative comparisons of adsorption isotherms and average Xe-129 chemical shifts using grand canonical Monte Carlo (GCMC) simulations employing the same methods and shielding functions used previously, We examine the temperature dependence of the Xe chemical shift at a fixed loading in NaY and silicalite and compare the predicted behavior with that of Xe-n in the alpha cages of NaA. Furthermore, we consider the most general case where the chemical shift reported by a Xe atom includes sampling environments in several crystallites and intercrystalline gas during acquisition of the NMR signal.
Keywords:NUCLEAR-MAGNETIC-RESONANCE;NA-A ZEOLITE;MOLECULAR-DYNAMICS SIMULATION;MONTE-CARLO SIMULATIONS;XE-129 NMR;MICROPOROUS SOLIDS;Y-ZEOLITES;CATION LOCATION;SELF-DIFFUSION;RARE-GASES