Effects of Adsorbate Molecules on the Quadrupolar Interaction of Framework Aluminum Atoms in Dehydrated Zeolite H,Na-Y
IR@IIP: CSIR-Indian Institute of Petroleum, Dehradun
View Archive Info| Field | Value | |
| Creator |
Jiao,Jian
Kanellopoulos,Johanna Behera,Babita Jiang,Yijiao Huang,Jun Reddy Marthala, V. R. Ray,S.S Wang,Wei Hunger,Michael |
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| Date |
2009-06-23T05:57:53Z
2009-06-23T05:57:53Z 2009-06-23T05:57:53Z |
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| Identifier |
http://hdl.handle.net/123456789/243
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| Description |
The effect of adsorbate molecules on the quadrupolar interaction of framework aluminum atoms with the
electric field gradient in dehydrated zeolite H,Na-Y has been studied by 27Al MAS NMR and 27Al MQMAS
NMR spectroscopy at magnetic fields of 9.4 and 17.6 T. Upon adsorption of molecules interacting with
bridging OH groups by hydrogen bonds (acetonitrile and acetone), the quadrupole coupling constant of
framework aluminum atoms was found to decrease from 16.0 MHz (unloaded zeolite) to 9.4 MHz. Adsorption
of molecules, which cause a proton transfer from the zeolite framework to the adsorbates (ammonia and
pyridine), reduces the quadrupole coupling constant to 3.8 MHz for coverages of 0.5-2 molecules per bridging
OH group. The experiments indicate that the quadrupole coupling constant of framework aluminum atoms in
dehydrated zeolite H,Na-Y reflects the chemical state of adsorbate complexes formed at bridging OH groups.
In agreement with earlier investigations it was found that a proton affinity of the adsorbate molecules of PA
) 812-854 kJ/mol is necessary to induce a proton transfer from the zeolite framework to the adsorbed
compounds. This proton transfer is accompanied by a strong improvement of the tetrahedral symmetry of
zeolitic framework AlO4 tetrahedra and a decrease of the electric field gradient.
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| Language |
en_US
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| Subject |
NMR
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| Title |
Effects of Adsorbate Molecules on the Quadrupolar Interaction of Framework Aluminum Atoms in Dehydrated Zeolite H,Na-Y
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| Type |
Article
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