DISTRIBUTION AND MOTION OF ORGANIC GUEST MOLECULES IN ZEOLITES

Hexamethylbenzene (HMB), adamantane, and naphthalene are adsorbed into zeolite Na-Y by a vapor phase impregnation method. Results from thermogravimetric analyses, Raman, and C-13 NMR measurements indicate that the organic species reside in the supercages of Na-Y. Proton multiple-quantum NMR spectroscopy is used to investigate the distribution of the organic species adsorbed within the cavities of Na-Y and the organic species occluded during the synthesis process into the intracrystalline voids of the cubic and hexagonal polytypes of faujasite and ZSM-18. Room temperature, multiple-quantum NMR measurements appear to yield the correct cluster size for single, isolated organic template molecules occluded within the cages of ZSM-18. At an average loading of one HMB molecule per supercage, the HMB molecules appear to undergo anisotropic motion inside the supercages of Na-Y. The room temperature, multiple-quantum NMR measurements indicate that hexamethylbenzene molecules associate in pairs. This spatial distribution implies that half of the supercages contain pairs of HMB molecules and half are empty. The multiple-quantum NMR measurements of the other organic guest molecules appear to be complicated by the fast motion of the guests within the intracrystalline voids of the zeolites.