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Mechanisms of Structure Direction in the Synthesis of Pure-Silica Zeolites. 1. Synthesis of TPA/Si-ZSM-5

Burkett, Sandra L. and Davis, Mark E. (1995) Mechanisms of Structure Direction in the Synthesis of Pure-Silica Zeolites. 1. Synthesis of TPA/Si-ZSM-5. Chemistry of Materials, 7 (5). pp. 920-928. ISSN 0897-4756. doi:10.1021/cm00053a017.

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The role of tetrapropylammonium (TPA) as a structure-directing agent in the sodium-free synthesis of pure-silica ZSM-5 (Si-ZSM-5) is investigated by solid-state ^1H-^(29)Si CP MAS NMR. It has previously been proposed that the mechanism of structure direction in a sodium-containing system involves preorganization of silicate species around the TPA ions with subsequent assembly of these inorganic-organic composite structures to yield crystalline Si-ZSM-5 with occluded TPA molecules.l ^1H-^(29)Si CP MAS NMR results indicate that short-range intermolecular interactions, i.e., on the order of van der Waals contact distances, are established during heating of the zeolite synthesis gel prior to the development of long-range order indicative of the ZSM-5 structure. These interactions are independent of the presence of sodium in the gel or the silica source used. An attempt to isolate the composite species by trimethylsilylation of the synthesis mixture was partially successful. These results provide additional evidence for the existence of preorganized, inorganic-organic composite structures during the synthesis of Si-ZSM-5. A modified mechanism of structure direction and crystal growth of Si-ZSM-5 is proposed.

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Davis, Mark E.0000-0001-8294-1477
Additional Information:© 1995 American Chemical Society. Received December 5, 1994. Revised Manuscript Received March 13, 1994. Financial support of this work has been provided by the Chevron Research and Technology Co. The authors thank Dr. Stacey Zones of the Chevron Research and Technology Co. for numerous helpful discussions. The authors also thank Professor R. A. van Santen and Dr. T. P. M. Beelen for preprints of their work.
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Chevron Research and Technology Co.UNSPECIFIED
Issue or Number:5
Record Number:CaltechAUTHORS:20180507-141346115
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Official Citation:Mechanisms of Structure Direction in the Synthesis of Pure-Silica Zeolites. 1. Synthesis of TPA/Si-ZSM-5 Sandra L. Burkett and Mark E. Davis Chemistry of Materials 1995 7 (5), 920-928 DOI: 10.1021/cm00053a017
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86258
Deposited By: George Porter
Deposited On:07 May 2018 22:53
Last Modified:15 Nov 2021 20:36

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