In situ NMR studies of alkylation reactions on solid acid catalysts /
In situ NMR studies following the alkylation of
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: |
| Summary: | In situ NMR studies following the alkylation of benzene to isopropylbenzene (cumene) in temperature ranges of 133 K to 523 K on two solid acid catalysts are reported. [13C] enriched and natural abundance reactants are used to follow the reactions and deduce possible pathways. The first catalyst is solid phosphoric acid (SPA), a well known industrial catalyst essentially comprised of phosphoric acid supported on silicon phosphates. Preliminary acidity and reactivity of the SPA catalyst is gauged by use of probe molecules and other adsorbates. Isopropyl benzene (cumene) formation occurs on this catalyst at 393 K. The alkylation process is regulated by a intermediate species formed from both alcohol and alkene alkylating agents. The second solid acid catalyst is Zeolite Beta, a twelve membered ring zeolite with three dimensional faulted structure. Alkylation of benzene to form cumene occurs readily at 133 K, upon this catalyst, though no reactive intermediates are observed. These studies use 2- propanol and / or propane as alkylating reagents. Both catalysts successfully alkylate benzene to form humane. Zeolite Beta though has much higher activity and a slightly higher selectivity for cumene formation in comparison to SPA in these studies. A modestly improved vacuum system and CAVERN (Cryogenic Adsorption Vessel Enabling Rotor Nestling) is also presented. The system utilizes superior vacuum pumps and components that reduce the sample contamination and attain lower ultimate vacuum. The CAVERN is slightly modified with a design feature that aids in more efficient evacuation of the device. The vacuum system is compatible with present CAVERN devices and techniques for low temperature studies. |
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| Item Description: | "Major subject: Chemistry". Vita. |
| Physical Description: | x, 74 leaves : illustrations ; 28 cm. Issued also on microfiche from Lange Micrographics. |
| Bibliography: | Includes bibliographical references: pages 64-68. |