Reaction of HY Zeolite with Molecular Fluorine

• Published in: Journal of catalysis Vol. 201; no. 1; pp. 80 - 88
• Main Authors: Sánchez, Norma A, Saniger, José M, d'Espinose de la Caillerie, Jean-Baptiste, Blumenfeld, Alexander L, Fripiat, José J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.07.2001; Elsevier
• Subjects: 27Al and 19F NMR; Catalysis; Catalysts: preparations and properties; Chemistry; dealumination; Exact sciences and technology; fluorination; General and physical chemistry; Ion-exchange; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; zeolite; Zeolites: preparations and properties; fluorination; zeolite; dealumination; 27Al and 19F NMR; Dealumination; Fluorine; Gaseous state; Solid state reaction; NMR spectrometry; Zeolite; Experimental study; Fluorination; Catalyst activity; Molecular sieve; Crystalline structure
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1006/jcat.2001.3226

At room temperature, gaseous F2 extracts tetrahedrally coordinated aluminum from the lattice of an acid, near-faujasite HY zeolite (Si/Al≈13) and forms fluoro-hydroxy-aluminum complexes of the type Al2F(OH)(5−n)+n in which Al is octahedrally coordinated. Moreover, the crystallinity of the zeolite is almost unchanged by the fluorination process. The HY dehydrated at 200°C under vacuum and treated under a F2 pressure of 300 mbar at room temperature is practically totally dealuminated. At lower pressure the transformation is partial. The coordination shell of the complex becomes unstable at about 500°C. Upon losing ligands, octahedral Al reverts partially to the tetrahedral coordination and is partially reinserted into the lattice. At a higher temperature an amorphous alumina phase is formed. 27Al and 19F high-resolution solid-state NMR, FT-IR, X-ray diffraction, and temperature-programmed desorption (TPD) are the main tools used in this work.