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Final Report: Combined NMR and Theoretical Investigation of Alkylation Reactions on Solid Acids
EPA Grant Number: R826122Title: Combined NMR and Theoretical Investigation of Alkylation Reactions on Solid Acids
Investigators: Haw, James F. , Nicholas, John B.
Institution: University of Southern California
EPA Project Officer: Karn, Barbara
Project Period: November 1, 1997 through October 31, 2000 (Extended to December 31, 2000)
Project Amount: $150,000
RFA: Technology for a Sustainable Environment (1997)
Research Category: Pollution Prevention/Sustainable Development
Description:
Objective:The approach used here to understand alkylation will embody our combined experimental-theoretical strategy that has proven to be successful for other problems. We will use solid state magic angle spinning nuclear magnetic resonance (NMR) techniques to characterize the most promising HF-replacement catalysts?zeolite Beta, BF3/alumina, and sulfonated zirconia. We will use in situ NMR to determine the nature of intermediates under true conditions of catalysis. Simultaneously, we will make extensive use of computational chemistry methods to verify experimental data, determine transition states, and predict how modification to the catalyst will effect the reaction mechanism. Summary/Accomplishments (Outputs/Outcomes):
The measurement of the type and number of acid sites on sulfated zirconia catalysts has been vexed by spectral assignment controversies. Using a combination of NMR experiments and theoretical methods, including chemical shift calculations at the GIAO-MP2 level, we resolved this problem. Quantitative studies revealed that the number of Br?nsted sites capable of protonating pyridine corresponded to only about 7 percent of the sulfur atoms on the catalyst we studied in the greatest depth. Additional Br?nsted sites were created on this catalyst with addition of water, a reaction not observed for sulfur-free zirconia. We found that we could prepare catalysts similar to sulfated zirconia adsorption of SO3 onto zirconia. We also used a combination of NMR and theory to identify the persistent carbenium ion on zeolite Beta, which we made by alkylation of benzene. A paper in preparation identifies this species as being key to hydrocarbon catalysis on Beta. Additional papers on both sulfated zirconia and zeolite Beta are in preparation. The investigation of BF3 on alumina was unproductive, but may be re-initiated with a new student.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
| Other project views: | All 14 publications | 6 publications in selected types | All 5 journal articles |
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Fu H, Song W, Haw JF. Polycyclic aromatics formation in HSAPO-34 during methanol-to-olefin catalysis: ex situ characterization after cryogenic grinding. Catalysis Letters 2001, Volume: 76, Number: 1-2, Page: 89-94. |
R826122 (Final) |
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Haw JF, Xu T. NMR studies of solid acidity. In: Eley DD, Haag WO, Gates BC, Knozinger H, eds. Advances in Catalysis. Volume 42. San Diego: Academic Press, 1998;115-180. |
R826122 (Final) |
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Haw JF, Zhang J, Shimizu K, Venkatraman TN, Luigi D.-P, Song W, Barich DH, Nicholas JB. NMR and theoretical study of acidity probes on sulfated zirconia catalysts. Journal of the American Chemical Society 2000;122(50):12561-12570. |
R826122 (Final) |
not available |
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Song WG, Nicholas JB, Sassi A, Haw JF. Synthesis of the heptamethylbenzenium cation in zeolite-beta: in situ NMR and theory. Catalysis Letters 2002;81(1-2):49-53 |
R826122 (Final) |
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Zhang JH, Nicholas JB, Haw JF. NMR and theoretical study of acid sites formed by adsorption of SO3 onto oxide surfaces. Angewandte Chemie-International Edition 2000;39(18):3302-+ |
R826122 (Final) |
not available |
solid acids, NMR spectroscopy, theoretical chemistry. , Sustainable Industry/Business, Scientific Discipline, RFA, Technology for Sustainable Environment, Sustainable Environment, Environmental Chemistry, toxic reagents, waste reduction, alkylation reaction, catalysts, green chemistry, aromatic hydrocarbons, chlorinated organic wastes, environmentally benign catalysts, solid-catalyzed reactions, catalysis, innovative technology, nuclear magnetic resonance, reformulation of gasoline, pollution prevention
Relevant Websites:
http://www.usc.edu/dept/chemistry/faculty/haw.htm
Progress and Final Reports:
Original Abstract