Synthesis of borosilicalite-1 with more than four boron per unit cell from fluoride containing media

More than four boron per unit cell has been introduced into the framework of silicalite-1, using fluorine containing media. The initial gels were of composition 9MF–xH3BO3–10SiO2–1.25TPABr–330 H2O with M = NH4, Na, K and Cs and x = 0.1–10. The syntheses were carried out in hydrothermal conditions at...

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Bibliographic Details
Published in:Journal of porous materials 2007-06, Vol.14 (2), p.191-204
Main Authors: Testa, F, Chiappetta, R, Crea, F, Aiello, R, Fonseca, A, Bertrand, J C, Demortier, G, Guth, J L, Delmotte, L, Nagy, J B
Format: Article
Language:English
Subjects:
Boron
Cesium ions
Chemical synthesis
Fluorine
Gels
NMR
Nuclear magnetic resonance
Silicalite
Unit cell
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Summary:More than four boron per unit cell has been introduced into the framework of silicalite-1, using fluorine containing media. The initial gels were of composition 9MF–xH3BO3–10SiO2–1.25TPABr–330 H2O with M = NH4, Na, K and Cs and x = 0.1–10. The syntheses were carried out in hydrothermal conditions at 170°C. The amount of incorporated TPA+ ions remains quasi constant (3.5–3.8/u.c.) up to 4 B/u.c., while it decreases with increasing boron content. The amount of tetrahedral B/u.c. can be as high as 8 in presence of K+ or Cs+ ions in the as-synthesized samples. It is observed that the preferential countercations to framework negative charges related to the presence of tetrahedral boron, [SiOB]−, are TPA+, K+ and Cs+ ions. It is interpreted, that the −4.0 ppm versus BF3.OEt2 NMR line stems from tetrahedral framework boron, while the −2.9 ppm NMR line represents both extraframework and/or tetracoordinated deformed framework boron in the structure.
ISSN:1380-2224
1573-4854
DOI:10.1007/s10934-006-9024-z