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129Xe NMR of adsorbed xenon and 1H NMR imaging: new methods to study the diffusion of gaseous hydrocarbons in a fixed bed of zeolite

N'Gokoli-Kekele P., Springuel-Huet M.-A., Bonardet J.-L., Dereppe J.-M., Fraissard J.

Bulletin of the Polish Academy of Sciences. Chemistry

2002

Vol. 50, No. 2

249-258

129Xe NMR of adsorbed xenon used as a probe and (1)H NMR imaging have been used to study the diffusion of hydrocarbons (benzene, n-hexane, paraxylene) during their adsorption or desorption in a fixed bed of zeolite crystallites. The simulation of experimental (129)Xe spectra using the nonuniform or the shrinking core models gives the concentration profiles of hydrocarbons, in the bed and in the zeolite crystallites, during their adsorption and leads to intracrystalline diffusion coefficients in good agreement with the literature. The (1)H NMR imaging allows one to visualize the progression of the diffusing molecules in the zeolite bed and also to determine their intracrystalline diffusion coefficients in the simplest cases.

Acid Properties of HY Zeolite Dealuminated by Steaming and EDTA Treatment - NMR, XPS and IR Studies

Datka J., Gil B., Złamaniec J., Batamack P., Fraissard J., Massiani P.

Polish Journal of Chemistry

1999

Vol. 73, nr 9

1535-1548

Steaming of zeolite is known to remove some Al atoms from the framework, which results in the formation of extraframework Al species and in the increase of the framework Si/Al ratio (Si/Al fram). The effects of these factors on the nature, concentration, strength, homogeneity and accessibility of the acid sites in Y zeolite were followed by an IR study of the adsorption/desorption of ammonia and pyridine.