Solid-state NMR of silicoaluminophosphate molecular sieves and aluminophosphate materials
β Scribed by Blackwell, C. S.; Patton, R. L.
- Book ID
- 118149861
- Publisher
- American Chemical Society
- Year
- 1988
- Tongue
- English
- Weight
- 559 KB
- Volume
- 92
- Category
- Article
- ISSN
- 0022-3654
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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
The advantages and drawbacks of various techniques that utilize multiple quantum magic angle spinning (MQMAS) NMR for studying molecular sieves and related materials are reviewed. The techniques include z-filtered MQMAS with rotor synchronization, MQMAS with cross-polarization and MQMAS with REDOR.
A chromium-substituted silicoaluminophosphate molecular sieve (CrAPSO-11) and a Cr-supported SAP041 molecular sieve (Cr/SAPO-11) were studied by XPS and rednctiowxidation (redox) cycles. The distribution of oxidation states as well as the average oxidation state for chromium were determined for both
Most solid materials are heterogeneous on a microscopic or a macroscopic scale, or both. Examples of heterogeneities are the phase structure of incompatible polymers, pores in ceramics, distributions in mechanical stress, variations in molecular order and mobility of extruded polymers, and chemical