FTIR and EPR Characterisation of Copper-Exchanged Mordenites and Beta Zeolites (Articolo in rivista)

Type
Label
  • FTIR and EPR Characterisation of Copper-Exchanged Mordenites and Beta Zeolites (Articolo in rivista) (literal)
Anno
  • 1997-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1039/A701477E (literal)
Alternative label
  • C. Oliva, E. Selli, A. Ponti, L. Correale, V. Solinas, E. Rombi, R. Monaci and L. Forni (1997)
    FTIR and EPR Characterisation of Copper-Exchanged Mordenites and Beta Zeolites
    in Journal of the Chemical Society. Faraday transactions (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • C. Oliva, E. Selli, A. Ponti, L. Correale, V. Solinas, E. Rombi, R. Monaci and L. Forni (literal)
Pagina inizio
  • 2603 (literal)
Pagina fine
  • 2608 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 93 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Dipartimento di Chimica Fisica ed Elettrochimica, Universita` di Milano, V ia Golgi 19, I-20133 Milano, Italy C.S.R.S.R.C. C.N.R., V ia Golgi 19, I-20133 Milano, Italy Dipartimento di Scienze Chimiche, Universita` di Cagliari, V ia Ospedale 72, I-09124 Cagliari, Italy (literal)
Titolo
  • FTIR and EPR Characterisation of Copper-Exchanged Mordenites and Beta Zeolites (literal)
Abstract
  • Sodium mordenites and beta zeolites, partially exchanged with Cu 2+ , were characterised by means of Fourier transform infrared (FTIR) and both continuous-wave and pulse electron paramagnetic resonance (EPR) spectroscopies, in order to shed light on the catalytic role of copper ions in the ammoxidation of 1-methylnaphthalene. FTIR analysis showed that ammonia interacts with both Brønsted and Lewis acid sites, while 1-methylnaphthalene is mainly coordinated through ?-complexes. The acidity of the catalysts was also determined through FTIR analysis of the adsorbed pyridine. The main changes in the coordination sphere of Cu 2+ ions were observed by EPR analysis after ammonia adsorption and after catalyst use, while adsorption of 1-methylnaphthalene had a very minor effect. Primary electron spin echo envelope modulation spectra after catalytic use showed the presence of organic radicals, having a relaxation time of longer than the Cu 2+ ions. The latter are confirmed as the active reaction centres and should be located in the side pockets of the mordenites, and be unaccessible to the aromatic system of 1-methylnaphthalene. This explains the higher selectivity observed with mordenites. In the more acidic beta zeolites the presence of copper ions on the walls of large channels initially favours side reactions, but also makes adsorbed ammonia more available for ammoxidation. (literal)
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