Solid-state /sup 29/Si NMR and infrared studies of the reactions of mono- and polyfunctional silanes with zeolite Y surfaces
The combined use of /sup 29/Si magic angle-spinning NMR spectroscopy and in situ infrared techniques allows for the first time the determination of the intrazeolitic reaction products and details of the interaction of various silanes with zeolitic protons in HY zeolite. Alkoxy groups at Me/sub 3/SiOMe and MeSi(OMe)/sub 3/ are readily lost to form hydroxy groups and then siloxane bridges to the zeolite framework. At elevated temperatures, alkyl groups are also split off from the silane, and more highly substituted siloxane species are generated which are anchored to the framework via two siloxane bridges. Chloro groups at trimethylchlorosilane are rapidly hydrolyzed by the surface hydroxy groups, and the resulting products follow the reaction pattern of the alkoxysilanes. Hexamethyldisilazane and trimethylsilane do not react irreversibly with the zeolite hydroxyls at 295 K but are as reactive as other silanes at 473 K. A major product with these silanes shows a unique NMR shift at about +40 ppm and is assigned to a Lewis acid or strongly hydrogen-bonded association of the anchored silicon species with a framework metal. Most of the reactions are more complex than those of halosilanes with the terminal hydroxyls of silica, indicating the extreme reactivity of bridged hydroxyl groups in zeolites. 36 references, 10 figures, 5 tables.
- Research Organization:
- E.I. Pont de Nemours and Company, Wilmington, DE (USA)
- OSTI ID:
- 5993397
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:14
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
SILANES
CHEMICAL REACTIONS
ZEOLITES
EXPERIMENTAL DATA
INFRARED SPECTRA
NMR SPECTRA
SILICON 29
DATA
EVEN-ODD NUCLEI
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
LIGHT NUCLEI
MATERIALS
MINERALS
NUCLEI
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
SILICON COMPOUNDS
SILICON ISOTOPES
SPECTRA
STABLE ISOTOPES
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation