CHARACTERIZATION OF DEALUMINATED ZEOLITES USING XE-129 NMR SPECTROMETRY AND LOW-PRESSURE ARGON ADSORPTION

This work compares the use of Xe-129 n.m.r. spectrometry and argon adsorption techniques for characterization of the micropore region of dealuminated Y and CSZ-1 zeolites. Low-pressure argon adsorption provides a measure of zeolite aperture sizes, whereas Xe-129 n.m.r. spectrometry gives an indication of dimensions of internal void volumes. The two analytical techniques detect subtle differences in the pore structure of Y zeolites due to dealumination method and steam treatment severity. Both techniques predict the presence of two microcrystalline phases in CSZ-1 zeolite and the collapse of one of the phases following severe steaming. Xe-129 n.m.r. spectrometry and argon adsorption techniques are useful for distinguishing small differences in pore structures of similar materials. The correlation between the two techniques suggests that both techniques are influenced by the energetics of the sorption process in addition to pore geometry.