Catalytic reactor and organometallic model studies of the mechanism of thiophene hydrodesulfurization

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dc.contributor.author Sauer, Nancy
dc.contributor.department Chemistry
dc.date 2018-08-16T03:43:23.000
dc.date.accessioned 2020-07-02T06:06:01Z
dc.date.available 2020-07-02T06:06:01Z
dc.date.copyright Wed Jan 01 00:00:00 UTC 1986
dc.date.issued 1986
dc.description.abstract <p>The reactivity of transition metal complexes of thiophene (Th) and 2,3- and 2,5-dihydrothiophenes (DHT) and catalytic reactor studies of thiophene and the dihydrothiophenes have been used to examine the mechanism for the hydrodesulfurization (HDS) of thiophene;Catalytic deuterium exchange of thiophene over HDS catalysts was modeled by the reaction of (pi)-thiophene complexes, CpRu(Th)('+) (where Th = thiophene, 2, or 3 methylthiophene or 2,5-dimethylthiophene) in CD(,3)OD with OH('-). The exchanges follow a rate law Rate = k CpRu(Th)('+) OH('-) which suggests a mechanism involving rate determining proton abstraction from the thiophene by OH('-) followed by deuteration by the solvent. Rates of exchange for the different hydrogens in the complexes follow the trend H(,2,5) >> H(,3,4) > methyl; the same order of reactivity which is observed over HDS catalysts;Reactor studies with thiophene and 2,3- and 2,5-DHT were done at 300(DEGREES) and 400(DEGREES)C over a Re/(gamma)-Al(,2)O(,3) HDS catalyst. At 400(DEGREES)C, the distributions of butane and 1 and 2-butenes were very similar. At 300(DEGREES) however, both 2,3- and 2,5-DHT gave butadiene as the major desulfurized product. Formation of thiophene and tetrahydrothiophene and the interconversion of the dihydrothiophenes was also observed over the catalysts. Deuterodesulfurization studies established that 2,5-DHT directly eliminates butadiene while butadiene formation from 2,3-DHT must involve several surface steps over the catalyst;Several reactions of the dihydrothiophenes over HDS catalysts were modeled using transition metal complexes of 2,3 and 2,5-DHT. The S-bound 2,3-DHT in W(CO)(,5)(2,3-DHT) is converted to tetrohydrothiophene upon treatment with HCl. When Fe(,2)(CO)(,9)2 is reacted in THF with 2,3-DHT though, no isolable Fe(CO)(,4)(2,3-DHT) complex is obtained, but small amounts of 2,5-DHT are observed by ('1)H NMR. Reaction of 2,5-DHT with Fe(,2)(CO)(,9) does result in the formation of Fe(CO)(,4)(2,5-DHT), which readily eliminates butadiene.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/8299/
dc.identifier.articleid 9298
dc.identifier.contextkey 6331141
dc.identifier.doi https://doi.org/10.31274/rtd-180813-11696
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/8299
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/81271
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/8299/r_8703758.pdf|||Sat Jan 15 02:09:08 UTC 2022
dc.subject.disciplines Inorganic Chemistry
dc.subject.keywords Chemistry
dc.subject.keywords Inorganic chemistry
dc.title Catalytic reactor and organometallic model studies of the mechanism of thiophene hydrodesulfurization
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 42864f6e-7a3d-4be3-8b5a-0ae3c3830a11
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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