[sup 1]H[[sup 27]Al] double-resonance experiments in solids. An unexpected observation in the [sup 1]H MAS spectrum of zeolite HZSM-5

Journal Article · Wed Oct 19 00:00:00 EDT 1994 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00100a034· OSTI ID:6735863

Beck, L W; White, J L; Haw, J F ^[1]

---

1. Texas A M Univ., College Station, TX (United States)

We report the existence of a previously unsuspected peak in the [sup 1]H magic angle spinning spectrum of commercially available HZSM-5 samples. At 298 K, this resonance is a broad shoulder on the downfield side of the Bronsted acid signal at 4.3 ppm. Cooling the sample caused the line to narrow, and a clear peak at 6.9 ppm was visible at 123 K. This technique resulted in selective broadening of the 4.3 and 6.9 ppm resonances as a result of conflicting averaging of the [sup 1]H-[sup 27]Al dipolar coupling. We conclude that the 6.9 ppm resonance corresponds to a novel aluminum-containing site in zeolite HZSM-5 and is not an artifact due to exchange with the Bronsted site or an aluminum-rich impurity phase. A possible interpretation of these results is a second Bronsted site for the zeolite. 49 refs., 8 figs.

• DOE Contract Number: FG03-93ER14354
• OSTI ID: 6735863
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 116:21; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
NMR SPECTRA
TEMPERATURE DEPENDENCE
ZEOLITES
CRYSTAL STRUCTURE
ALUMINIUM COMPOUNDS
BROENSTED ACIDS
QUADRUPOLES
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MINERALS
MULTIPOLES
SILICATE MINERALS
SPECTRA
TEMPERATURE RANGE
400201* - Chemical & Physicochemical Properties
661300 - Other Aspects of Physical Science- (1992-)