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iv
TABLE OF CONTENTS
Dedication ii
Acknowledgements iii
List of Tables vii
List of Figures viii
List of Schemes x
Abstract xi
Introduction 1
Chapter 1: The Role of Zeolites in Heterogeneous Catalysis 6
1.1 Heterogeneous Catalysis 6
1.2 Zeolites and Zeotypes 6
1.3 ZSM-5 10
1.4 SAPO-34 12
1.5 Mordenite 15
1.6 Ferrierite 18
1.7 Beta 18
1.8 Commercial Uses 20
1.9 References 23
Chapter 2: Methanol-to-Olefin Catalysis 25
2.1 Methanol-to-Hydrocarbon Catalysis 25
2.2 Current Chemical Production 26
2.2.1 Plastics 26
2.2.2 Methanol 27
2.3 Methanol-to-Gasoline Catalysis 28
2.4 Methanol-to-Olefin Catalysis 29
2.5 Direct Mechanisms in MTO Catalysis 29
2.5.1 Carbene Mechanism 31
2.5.2 Carbonium Mechanism 32
2.5.3 Oxonium Ylide Mechanism 34
2.5.4 Alkoxy Chain Growth Mechanism 35
2.6 Early Indirect Hydrocarbon Pool Mechanisms 36
2.6.1 Cyclic Olefin Mechanism 37
Object Description
| Title | Modification of methanol-to-olefin hydrocarbon pool species by oxygenates on acidic zeolites |
| Author | Hayman, Miranda Jeanette |
| Author email | mirandah@usc.edu; mirandahayman@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemistry |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2011-02-11 |
| Date submitted | 2011 |
| Restricted until | Unrestricted |
| Date published | 2011-04-26 |
| Advisor (committee chair) | Haw, James F. |
| Advisor (committee member) |
Flood, Thomas C. Jessen, Kristian |
| Abstract | The mechanism of methanol-to-olefin (MTO) catalysis employs organic reaction centers, both aromatic and olefinic, to generate olefins on acid zeolites. Generally, propene is the favored MTO olefin on most zeolite catalysts, but ethylene is a more desirable olefin due to its prevalence in consumer plastics. Much research has been conducted to alter the MTO product selectivities to favor ethylene. This focus of this dissertation is selective modification of the olefinic reaction centers, converting them into aromatic reaction centers known to be responsible for the majority of ethylene production.; Formaldehyde reactivity was studied on HSAPO-34, and found to react with propene through a Prins reaction to form butadiene, which readily cyclized to aromatic species. Evidence of formaldehyde formation was observed from methanol oxidation on the stainless-steel surface of the reactor tubing. This reaction was then studied in HZSM-5 where olefinic reaction centers dominate the hydrocarbon pool. The olefinic reaction centers were converted to aromatic species, and a significant increase in ethylene selectivity was observed. Other oxygenated species, such as acetaldehyde, were also studied in conjunction with methanol on HZSM-5 and an improvement in ethylene selectivity was noted. The consequence of the increased ethylene selectivity however was an increase in the rate of deactivation due to the accelerated formation of aromatic species. |
| Keyword | MTO; methanol-to-olefins; zeolite; heterogeneous catalysis; hydrocarbon pool; HZSM-5 |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3780 |
| Contributing entity | University of Southern California |
| Rights | Hayman, Miranda Jeanette |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Hayman-4358 |
| Archival file | uscthesesreloadpub_Volume23/etd-Hayman-4358.pdf |
Description
| Title | Page 4 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | iv TABLE OF CONTENTS Dedication ii Acknowledgements iii List of Tables vii List of Figures viii List of Schemes x Abstract xi Introduction 1 Chapter 1: The Role of Zeolites in Heterogeneous Catalysis 6 1.1 Heterogeneous Catalysis 6 1.2 Zeolites and Zeotypes 6 1.3 ZSM-5 10 1.4 SAPO-34 12 1.5 Mordenite 15 1.6 Ferrierite 18 1.7 Beta 18 1.8 Commercial Uses 20 1.9 References 23 Chapter 2: Methanol-to-Olefin Catalysis 25 2.1 Methanol-to-Hydrocarbon Catalysis 25 2.2 Current Chemical Production 26 2.2.1 Plastics 26 2.2.2 Methanol 27 2.3 Methanol-to-Gasoline Catalysis 28 2.4 Methanol-to-Olefin Catalysis 29 2.5 Direct Mechanisms in MTO Catalysis 29 2.5.1 Carbene Mechanism 31 2.5.2 Carbonium Mechanism 32 2.5.3 Oxonium Ylide Mechanism 34 2.5.4 Alkoxy Chain Growth Mechanism 35 2.6 Early Indirect Hydrocarbon Pool Mechanisms 36 2.6.1 Cyclic Olefin Mechanism 37 |
