SYNTHESIS OF NEW SILICA-RICH CUBIC AND HEXAGONAL FAUJASITES USING CROWN-ETHER-BASED SUPRAMOLECULES AS TEMPLATES

The direct synthesis of faujasite-type zeolites with a high framework Si/Al ratio has been the subject of a great deal of research work without achieving much success. Until now, no well crystallized faujasite-type zeolite with a framework Si/Al ratio higher than 3 could be obtained without a postsynthesis dealumination. By using organic templates of the crown-ether family, two pure and well-crystallized faujasite-type zeolites were synthesized with a framework Si/Al ratio approaching 5: (1) the cubic phase with 15-crown-5, and (2) the hexagonal phase with 18-crown-6. © 1990 Butterworth-Heinemann.