The hydrogenolysis of isobutane on iridium

dc.contributor.author Klima, Rudolph
dc.contributor.department Chemistry
dc.date 2018-08-17T10:53:32.000
dc.date.accessioned 2020-07-02T06:07:16Z
dc.date.available 2020-07-02T06:07:16Z
dc.date.copyright Sat Jan 01 00:00:00 UTC 1983
dc.date.issued 1983
dc.description.abstract <p>The hydrogenolysis of isobutane on iridium has been investigated over the pressure range 0-100 torr. The iridium catalyst is a 48.5 (ANGSTROM) thick film vapor deposited on the inside of a round bottom flask under ultra high vacuum conditions. Methane was observed to be the only reaction product. Adsorption experiments indicate competitive adsorption to occur for hydrogen and hydrocarbon with respect to the iridium;Thermal desorption studies show hydrocarbon adsorption to be irreversible. These studies also show only monocarbon fragments desorb from iridium when the film is exposed to hydrogen and heat. There appears to be three adsorption states on polycrystalline iridium for hydrogen. The two states desorbing at 110(DEGREES)C and 160(DEGREES)C are due to adsorption of atomic hydrogen. The state appearing at 320(DEGREES)C is due to hydrogen bound to carbonaceous fragments chemisorbed to the surface. Hydrocarbon adsorption increases as the catalyst's temperature is increased, while hydrogen adsorption decreases. Dependence of reaction rate on hydrogen and isobutane partial pressures was established by measurements of initial rates of methane production. The following rate law fit the experimental data very well:;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);(UNFORMATTED TABLE FOLLOWS)Temperature 209(DEGREES)C 175(DEGREES)C;A(molecules/site sec torr) 1.75 x 10('-2) 1.46 x 10('-2);B(torr('- 1/2)) .25 1.90;C(torr('- 1/2)) .81 .81;D(dimensionless) 6.34 6.12(TABLE ENDS);This rate equation was derived via a Langmuir Hinshelwood reaction mechanism. The hydrogen order varies from +2 to -1. The isobutane order varies from +1 to -1. The hydrogen adsorption equilibrium constant decreases as temperature increases, indicating that hydrogen is more mobile on the surface at high temperatures. The activation energy for isobutane hydrogenolysis is 24.20 kcal/mole.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/8493/
dc.identifier.articleid 9492
dc.identifier.contextkey 6335131
dc.identifier.doi https://doi.org/10.31274/rtd-180813-12772
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/8493
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/81487
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/8493/r_8407092.pdf|||Sat Jan 15 02:12:06 UTC 2022
dc.subject.disciplines Physical Chemistry
dc.subject.keywords Chemistry
dc.title The hydrogenolysis of isobutane on iridium
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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