Characterization of framework and extra-framework aluminumspecies in non-hydrated zeolites Y by 27Al spin-echo, high-speed MAS, and MQMAS NMR spectroscopy at B0 = 9.4 to 17.6 T
IR@IIP: CSIR-Indian Institute of Petroleum, Dehradun
View Archive Info| Field | Value | |
| Creator |
Jiao,Jian
Kanellopoulos,Johanna Wang,Wei Ray,S.S Foerster,Hans Freude,Dieter Hunger,Michael |
|
| Date |
2009-06-23T06:44:01Z
2009-06-23T06:44:01Z 2009-06-23T06:44:01Z |
|
| Identifier |
http://hdl.handle.net/123456789/247
|
|
| Description |
27Al spin-echo, high-speed MAS (nrot ¼ 30 kHz), and MQMAS NMR spectroscopy in magnetic fields of
B0 ¼ 9.4, 14.1, and 17.6 T were applied for the study of aluminum species at framework and extra-framework
positions in non-hydrated zeolites Y. Non-hydrated g-Al2O3 and non-hydrated aluminum-exchanged zeolite Y
(Al,Na-Y) and zeolite H,Na-Y were utilized as reference materials. The solid-state 27Al NMR spectra of steamed
zeolite deH,Na-Y/81.5 were found to consist of four signals. The broad low-field signal is caused by a
superposition of the signals of framework aluminum atoms in the vicinity of bridging hydroxyl protons and
framework aluminum atoms compensated in their negative charge by aluminum cations (diso ¼ 70 10 ppm,
CQCC ¼ 15.0 1.0 MHz). The second signal is due to a superposition of the signals of framework aluminum
atoms compensated by sodium cations and tetrahedrally coordinated aluminum atoms in neutral extraframework
aluminum oxide clusters (diso ¼ 65 5 ppm, CQCC ¼ 8.0 0.5 MHz). The residual two signals were
attributed to aluminum cations (diso ¼ 35 5 ppm, CQCC ¼ 7.5 0.5 MHz) and octahedrally coordinated
aluminum atoms in neutral extra-framework aluminum oxide clusters (diso ¼ 10 5 ppm, CQCC ¼ 5.0 0.5
MHz). By chemical analysis and evaluating the relative solid-state 27Al NMR intensities of the different signals of
aluminum species occurring in zeolite deH,Na-Y/81.5 in the non-hydrated state, the aluminum distribution in this
material was determined.
|
|
| Language |
en_US
|
|
| Subject |
NMR
Zeolites |
|
| Title |
Characterization of framework and extra-framework aluminumspecies in non-hydrated zeolites Y by 27Al spin-echo, high-speed MAS, and MQMAS NMR spectroscopy at B0 = 9.4 to 17.6 T
|
|
| Type |
Article
|
|