OBSERVATION OF NONFRAMEWORK AL SPECIES IN ZEOLITE-BETA BY SOLID-STATENMR-SPECTROSCOPY

Authors
Citation
F. Deng et al., OBSERVATION OF NONFRAMEWORK AL SPECIES IN ZEOLITE-BETA BY SOLID-STATENMR-SPECTROSCOPY, JOURNAL OF PHYSICAL CHEMISTRY B, 102(27), 1998, pp. 5252-5256
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry Physical
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
1520-6106 → ACNP
Volume
102
Issue
27
Year of publication
1998
Pages
5252 - 5256
Database
ISI
SICI code
1089-5647(1998)102:27<5252:OONASI>2.0.ZU;2-D
Abstract
Dealumination of zeolite beta by hydrothermal or calcination treatment s has been investigated in detail using H-1 magic angle spinning (MAS) , H-1((27)A1) spin echo double-resonance, and Al-27 MAS NMR. The NMR e xperiments provide direct evidence for the existence of nonframework A l species in zeolite beta, which give rise to a H-1 resonance at ca. 2 .7 ppm and two Al-27 signals at ca. 30 and 0 ppm (corresponding to 5- and 6-coordiante Al, respectively). The nonframework 6- and 5-coordina te Al species do not revert to framework 4-coordinate Al (54 ppm) in t he dehydration process of zeolite beta. For the Al-27 Signal at 30 ppm , hydration may probably lead to a dispersion in its chemical shift or quadrupole interaction, which broadens its line width in the hydrated sample.