Reactions of Halogenated Ethylenes on the α-Cr₂O₃ (101̅2) Surface

dc.contributor.authorMinton, Mary Amandaen
dc.contributor.committeechairCox, David F.en
dc.contributor.committeememberOyama, Shigeo Teden
dc.contributor.committeememberMorris, John R.en
dc.contributor.committeememberDillard, John G.en
dc.contributor.committeememberHanson, Brian E.en
dc.contributor.departmentChemical Engineeringen
dc.date.accessioned2014-03-14T20:16:24Zen
dc.date.adate2006-11-13en
dc.date.available2014-03-14T20:16:24Zen
dc.date.issued2006-09-07en
dc.date.rdate2008-11-13en
dc.date.sdate2006-09-18en
dc.description.abstractThe thermally induced reaction of halogenated ethylenes on the α-Cr₂O₃ (101̅2) single crystal surface results in the formation of gas phase hydrocarbons including acetylene, ethylene, butadiene, and dihydrogen, and deposition of surface chlorine adatoms. No surface carbon or combustion products are observed in any reactions indicating no thermally induced C-C bond cleavage occurs and surface lattice oxygen is not incorporated into surface intermediates. Thermal desorption spectroscopy indicates that in all halogenated ethylene reactions acetylene is the major product, regardless of the reaction scheme. The surface reactions of halogenated ethylenes are proposed to proceed through C-X (X=halogen) bond cleavage to form surface halogen adatoms and surface C2 hydrocarbon fragments. Halogen adatom deposition affects reaction barriers to hydrocarbon formation, and eventually shuts down surface chemistry. Photoemission and near edge x-ray absorption fine structure spectra show that all studied reactants undergo some C-X bond cleavage upon low temperature adsorption forming adsorbed C2 fragments and halogen adatoms. Photoemission for each reaction system shows at least two C1s features (283.0-286.0 eV) and two Cl2p features (2p<sub>3/2</sub>=198.0-201.0 eV) with higher binding energy features associated with molecularly intact halogenated ethylenes and lower binding energy features associated with dissociated surface species. Near edge x-ray absorption fine structure spectra taken, corresponding to photoemission spectra, indicate the occurrence of C1s→π∗ transitions, indicating intact π-systems are present. Heating the surface results in a reduction in intensity of higher energy photoemission and near edge x-ray absorption fine structure indicative of a decrease in surface C-X bonds.en
dc.description.degreePh. D.en
dc.identifier.otheretd-09182006-091123en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09182006-091123/en
dc.identifier.urihttp://hdl.handle.net/10919/29014en
dc.publisherVirginia Techen
dc.relation.haspartMMintondissertation.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectvinylideneen
dc.subjectchlorovinylen
dc.subjectvinylen
dc.subjectbutadieneen
dc.subjectethyleneen
dc.subjectacetyleneen
dc.subjecthalocarbonsen
dc.titleReactions of Halogenated Ethylenes on the α-Cr₂O₃ (101̅2) Surfaceen
dc.typeDissertationen
thesis.degree.disciplineChemical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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