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The adsorption of benzene on dehydrated NaX (Si/Al=1.23) and NaY (Si/Al=2.49, 2.70) zeolites has been studied directly by 1 H and 13 C NMR measurements of the adsorbed benzene and probed indirectly by the combination of 129 Xe NMR and isotherm measurements of the coadsorbed xenon. Powders zeolite samples with varied adsorbate concentrations were investigated. Detailed macroscopic and microscopic adsorption phenomena of benzenc on faujasite-type zeolites, including the loading capacity, mobility, and sites of adsorption, are presented in terms of measurements of NMR line widths and chemical shifts

The adsorption behavior of benzene on dehydrated NaY zeolite has been studied by means of 129Xe n.m.r. and isotherm measurements of adsorbed xenon followed by proton and 13C n.m.r. of adsorbed benzene. Samples with varied benzene loadings were investigated. We found that to obtain a homogeneous molecular distribution in the zeolite cavities, thermal pretreatment of the sample at temperatures above 250°C for a period of several hours was necessary. The maximum number of benzene molecules that can be loaded within a zeolite supercage is found to lie between 4.9 and 5.2. 129Xe n.m.r. has provided valuable information about the arrangement and mobility of adsorbed benzene. To confirm the effect of heat treatment on benzene distribution within NaY supercages, we also examined the proton and 13C n.m.r. spectra of adsorbed benzene and compared them with published results.

The sorption and transport properties of benzene on dehydrated NaX and NaY zeolites have been investigated directly by 1H and 13C NMR measurements of the adsorbed benzene and probed indirectly by 129Xe NMR of the coadsorbed xenon. Dehydrated NaX and NaY zeolite adsorbate samples containing various adsorbate concentrations and having various sample bed configurations, which were subjected to different preparatory and experimental conditions, have been examined. Thermal treatment at a temperature (>250 °C) much greater than the boiling point of bulk benzene (80 °C) for an extended period of several hours is indispensable to ensure a homogeneous benzene distribution within the supercages of the faujasite-type zeolites.