Preparation of high-silica faujasites by treatment with silicon tetrachloride

摘要: NaY has been dealuminated in highly controlled conditions by SiCl4. The materials thus obtained, after subsequent washing and ammonium exchange, were characterized chemical analysis, thermogravimetry, X-ray diffraction, infrared spectroscopy of the framework surface hydroxyl groups 29Si nuclear magnetic resonance spectroscopy.In order to obtain crystalline a reproducible way, very specific dealumination procedure be followed. mechanism is complex always combines direct isomorphic substitution with acid leaching aluminium. obtained have continuously varying properties as far unit-cell dimensions vibrations are concerned. In contrast, amount extra-lattice aluminium retained zeolite reaches maximum at intermediate degrees dealumination.