http://www.cnr.it/ontology/cnr/individuo/prodotto/ID181711

Identification of cationic and oxidic caesium species in basic Cs-overloaded BEA zeolites (Articolo in rivista)

Type

Articolo in rivista (Classe)
Prodotto della ricerca (Classe)

Label

Identification of cationic and oxidic caesium species in basic Cs-overloaded BEA zeolites (Articolo in rivista) (literal)

Anno

2006-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

10.1016/j.micromeso.2005.11.036 (literal)

Alternative label

C. Bisio ; P. Massiani ; K. Fajerwerg ; L. Sordelli ; L. Stievano ; E.R. Silva ; S. Coluccia ; G. Martra (2006)
Identification of cationic and oxidic caesium species in basic Cs-overloaded BEA zeolites
in Microporous and mesoporous materials (Print); ELSEVIER, NEW YORK (Stati Uniti d'America)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

C. Bisio ; P. Massiani ; K. Fajerwerg ; L. Sordelli ; L. Stievano ; E.R. Silva ; S. Coluccia ; G. Martra (literal)

Pagina inizio

175 (literal)

Pagina fine

187 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

90 (literal)

Rivista

Microporous and mesoporous materials (Rivista)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo

1-3 (literal)

Note

ISI Web of Science (WOS) (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

Dipartimento di Chimica IFM and NIS Centre of Excellence, Universita` di Torino, Via P. Giuria 7, 10125 Torino, Italy Laboratoire de Reactivitè de Surface, UMR 7609, Universite´ Pierre et Marie Curie, 75252 Paris, France CNR-ISTM, Via C. Golgi 19, 20133 Milano, Italy Departamento de Engenharia Quimica, Instituto Superior Te´cnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal (literal)

Titolo

Identification of cationic and oxidic caesium species in basic Cs-overloaded BEA zeolites (literal)

Abstract

A parent acidic H-BEA with crystallites very small in size and high external surface area was used to prepare a series of materials loaded with increasing Cs+ contents by firstly ion-exchange and then impregnation with CsOH solutions. The monitoring of the ionexchange process by chemical analysis and by IR spectroscopy in presence of CO or NH3 reveals that a relevant amount of Brønsted acid sites in dehydrated H-BEA is related to framework Al sites that, in aqueous solution, turn into partially extraframework Al species unable to act any longer as sites of cationic exchange. This limits the exchange capacity in solution and higher levels of ion-exchange are attained by subsequent impregnation and calcination. A possible explanation for such a behaviour is proposed. The formation of carbonates by adsorption of CO2, monitored by IR, confirms that the basic character induced on framework oxygen atoms by exchange of H+ with Cs+ is significantly weaker than that reached upon Cs-overloading. For the latter, the strong basicity is related to the presence of Cs2O-like nanoparticles (also detected by EXAFS), dispersed within the zeolite pores (as shown by pore volume and TEM/EDX measurements). IR spectroscopy of adsorbed CO shows that Cs+ as countercations or as surface sites of occluded Cs2O-like species exhibit a similar Lewis acid strength. Noticeably, in Cs-overloaded BEA, pairs of Cs+ sites (formed by two countercations and/or one countercation and a Cs+ at the surface of Cs2O-like particles) are present, where CO can be adsorbed in a head-tail form, producing a distinct vCO band at 2145 cm-1. (literal)

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