Effect of the support on the basic and catalytic properties of KF

Jean Marc Clacens, Daisy Genuit, Luc Delmotte, Amado Garcia-Ruiz, Gérard Bergeret, Ramon Montiel, Joseph Lopez, François Figueras

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Abstract

KF supported by various supports was characterized by DTG-DTA coupled with mass spectral analysis of the gases evolved by the solid, in situ XRD, calorimetry, 19F NMR spectroscopy, and tested in the Michael addition of cyclohexene-2-one with nitroalkanes. After dehydration at low temperatures, from 19F NMR spectroscopy F is in part as KF when the support is α-alumina but only as K3AlF6 when the support is γ-alumina. During activation no fluorine is lost. On α-alumina KF is detected by XRD only after calcination at about 723 K and results in part of the decomposition of K3AlF6; it disappears with formation of K2AlF5 and KAlO2 at higher temperatures. A comparison of the results obtained by XRD and NMR suggests that KF is well dispersed on α-alumina. KF/α-alumina is a strong base, stronger than KF on γ-alumina, and more active for Michael reactions. On KF/α-alumina the Michael condensation of 2-cyclohexen-1-one with nitroalkanes can be achieved in 5 min with an equimolar mixture of reactants. Solvent-free reactions can also be achieved reaching 75% yield in adduct after 8 h, and KF/α-alumina is also active after simple drying at 393 K, avoiding the usual activation at higher; temperatures. © 2003 Elsevier Inc. All rights reserved.
Original languageAmerican English
Pages (from-to)483-490
Number of pages433
JournalJournal of Catalysis
DOIs
StatePublished - 25 Jan 2004
Externally publishedYes

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Clacens, J. M., Genuit, D., Delmotte, L., Garcia-Ruiz, A., Bergeret, G., Montiel, R., Lopez, J., & Figueras, F. (2004). Effect of the support on the basic and catalytic properties of KF. Journal of Catalysis, 483-490. https://doi.org/10.1016/j.jcat.2003.09.009