Adsorption effects in aluminophosphate molecular sieves studied by27Al double-rotation NMR
β Scribed by R. Jelinek; B. F. Chmelka; Y. Wu; M. E. Davis; J. G. Unlan; R. Gronsky; A. Pines
- Book ID
- 112404220
- Publisher
- Springer US
- Year
- 1992
- Tongue
- English
- Weight
- 685 KB
- Volume
- 15
- Category
- Article
- ISSN
- 1011-372X
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π SIMILAR VOLUMES
Solid-state 27AI NMR spectra of seve ra l aluminophosphate molecular sieves have been recorded with conventional magic-angle spinning (MAS), double-rotation (DOR) and quadrupole nutation with fast MAS. Enhanced resolution was obtained in the quadrupole nutation experiment at certain radiofrcqucncy p
Two-dimensional multiquantum MAS-NMR spectroscopy (2D-MQ) has been applied to the discrimination of the different 27A1 sites in several aluminophosphate molecular sieves. It is shown that a new quintuple-quantum MAS-NMR method (2D-5Q) gives an extraordinary improved resolution compared to the DOR or
The average 27Al-31P distances in an aluminophosphate, AlPO4-5, and in a silicoaluminophosphate, SAPO-11, were determined by using Spin Echo DOuble Resonance (SEDOR). A calculated SEDOR curve was fitted to the data in order to obtain the dipolar coupling constant. The tetrahedral surrounding of 27Al
Three CaNaA zeolites, in which, respectively, 49%, 65% and 83% of the Na + cations were exchanged with Ca 2+ ions, along with a NaA sample were studied by thermogravimetry, temperature-programmed DRIFT spectroscopy and MAS NMR. Thermogravimetric desorption profiles of the Ca 2+ exchanged zeolites sh
Al solid state NMR allows the isotropic chemical shift and quadrupolar interaction parameters for the four crystallographitally inequivalent AIOs sites in kyanite, a polymorph of AlsSiOs, to be deduced. Magic angle spinning at two fields ( 11.7 and 17.55 T), satellite transitions and double rotation