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28
2.3. Methanol-to-Gasoline Catalysis
The 1970s saw two major energy crises: the Arab oil embargo in late
1973 and an Iranian regime change in 1979 that disrupted crude oil refining
in the country. During this decade, there was a renewed interest in
alternative fuels and chemicals, stimulating the advancement of MTH
technologies. Methanol-to-gasoline (MTG) catalysis was one product of this
revolution, and was first patented by Mobil Oil Corporation in 19765 and
released in peer-reviewed literature in 1977.6
In this process, methanol is catalyzed over HZSM-5 to produce
gasoline boiling range alkanes (C4-C10) and aromatics. Mobil chemists
discovered the process while attempting to make synthetic gasoline from
methanol and isobutene on HZSM-5. It was assumed the methanol would
add to the isobutene through either a methyl cation (CH3
+) or a carbene
(:CH2) mechanism, producing high-octane gasoline.7 The result of the
reaction however was not only a liquid mixture similar to high-octane
gasoline, but additional gaseous products. Through mass balance, it was
determined that methanol had reacted, but not the isobutene as expected.
The same result was then achieved with methanol as the only reactant.
In 1979, the commercial viability of the process was untested, but the
government of New Zealand chose this new technology over the trusted
Fischer-Tropsch to produce synthetic gasoline.2,8 By 1986, they were
generating enough gasoline to supply a third of the country’s need. The
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 39 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 28 2.3. Methanol-to-Gasoline Catalysis The 1970s saw two major energy crises: the Arab oil embargo in late 1973 and an Iranian regime change in 1979 that disrupted crude oil refining in the country. During this decade, there was a renewed interest in alternative fuels and chemicals, stimulating the advancement of MTH technologies. Methanol-to-gasoline (MTG) catalysis was one product of this revolution, and was first patented by Mobil Oil Corporation in 19765 and released in peer-reviewed literature in 1977.6 In this process, methanol is catalyzed over HZSM-5 to produce gasoline boiling range alkanes (C4-C10) and aromatics. Mobil chemists discovered the process while attempting to make synthetic gasoline from methanol and isobutene on HZSM-5. It was assumed the methanol would add to the isobutene through either a methyl cation (CH3 +) or a carbene (:CH2) mechanism, producing high-octane gasoline.7 The result of the reaction however was not only a liquid mixture similar to high-octane gasoline, but additional gaseous products. Through mass balance, it was determined that methanol had reacted, but not the isobutene as expected. The same result was then achieved with methanol as the only reactant. In 1979, the commercial viability of the process was untested, but the government of New Zealand chose this new technology over the trusted Fischer-Tropsch to produce synthetic gasoline.2,8 By 1986, they were generating enough gasoline to supply a third of the country’s need. The |
