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Titolo:
An examination of confinement effects in high-silica zeolites
Autore:
Yang, L; Trafford, K; Kresnawahjuesa, O; Sepa, J; Gorte, RJ; White, D;
Indirizzi:
Univ Penn, Dept Chem Engn, Philadelphia, PA 19104 USA Univ Penn Philadelphia PA USA 19104 Chem Engn, Philadelphia, PA 19104 USA Univ Penn, Dept Chem, Philadelphia, PA 19104 USA Univ Penn Philadelphia PA USA 19104 Dept Chem, Philadelphia, PA 19104 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 10, volume: 105, anno: 2001,
pagine: 1935 - 1942
SICI:
1520-6106(20010315)105:10<1935:AEOCEI>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
STOICHIOMETRIC ADSORPTION COMPLEXES; C-13 CHEMICAL-SHIFT; H-MFI; MOLECULAR-MOTION; SOLID ACIDS; H-ZSM-5; MORDENITE; HEATS; NMR; CATALYSIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
38
Recensione:
Indirizzi per estratti:
Indirizzo: Gorte, RJ Univ Penn, Dept Chem Engn, Philadelphia, PA 19104 USA Univ PennPhiladelphia PA USA 19104 Philadelphia, PA 19104 USA
Citazione:
L. Yang et al., "An examination of confinement effects in high-silica zeolites", J PHYS CH B, 105(10), 2001, pp. 1935-1942

Abstract

The environment provided by the zeolite channels has been examined in high-silica zeolites having the MFI (ZSM-5). CHA (Chabazite), MOR (Mordenite), TON (ZSM-22), MTW (ZSM-12), FER (Ferrierite), and FAU (Faujasite) structures. Calorimetric measurements of CH4 and O-2 at similar to 210 K showed thatstructure affects the adsorption properties in a manner which depends on the pore dimensions. The differential heats for CH4 at low coverage were 28 kJ/mol in FER, 27 kJ/mol in TON, 25 kJ/mol in MOR, 21 kJ/mol in MFI, 20.5 kJ/mol in MTW, 19.5 kJ/mol in CHA, and 14 kJ/mol in FAU. However, calorimetric data for acetonitrile in the acidic forms of these zeolites gave heats that were independent of structure within experimental error, with differential heats for the 1:1 adsorption complexes all being 100 +/- 10 kJ/mol. A possible explanation lies in the additional orientation-dependent interaction resulting from the hydrogen bonding. These topology-sensitive, orientational interactions are observable in the temperature-sensitive, methyl-proton, NMR line shapes, where it is found that the barriers to reorientation of 1:1 adsorption complexes are much higher in small-pore zeolites. The implications of these measurements to "confinement" effects in catalysis are discussed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/01/20 alle ore 00:49:56