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dc.contributor.advisorMeyer, Randallen_US
dc.contributor.authorYin, Junen_US
dc.date.accessioned2012-12-07T11:13:36Z
dc.date.available2012-12-07T11:13:36Z
dc.date.created2011-08en_US
dc.date.issued2012-12-07
dc.date.submitted2011-08en_US
dc.identifier.urihttp://hdl.handle.net/10027/8845
dc.description.abstractThe selective catalytic reduction (SCR) of NOx by hydrocarbons on noble metals is critically important to the implementation of leaner-burning, more fuel-efficient combustion engines in order to handle the increased amount of NOx that is produced. Understanding the reaction mechanisms and pathways is essential for designing an effective catalytic system for exhaust treatment. As one small part of this effort, we focus on the interaction of nitrogen atoms and simple unsaturated hydrocarbons such as ethylene and acetylene on the Pt(111) surface under ultra high vacuum conditions to understand the potential intermediates in NOx reduction. In this study, we employ a variety of surface techniques, including temperature programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) in an attempt to identify reaction pathways in hydrocarbon SCR. Three interesting observations have been made. First, we observed the presence of π-bonded ethylene below 220 K, indicating a switch in the preferred binding site for ethylene on N-Pt(111) as compared to the clean surface. This result suggests that nitrogen could potentially serve as a promoter in metal catalyzed hydrogenation reactions. Second, the formation of ammonia is observed through ND3 desorption by using isotopically labeled ethylene or acetylene at 500 K. Because direct reaction between nitrogen atoms and hydrogen does not proceed to form ammonia, the appearance of ammonia is believed to be the result of a reaction between N atoms with coadsorbed ethynyl (CCH). This route to ammonia synthesis has not been previously observed under UHV conditions. Third, above 560 K, CN coupling occurs as indicated by the desorption of HCN and the identification of CNH2 with RAIRS. In addition, a new dual UHV/“high-pressure” chamber has been constructed and tested through two proof of principle experiments. First, nitrogen adsorption on Ni(110) has been examined at pressures ranging up to the torr level. Second, we have studied the hydrogenation of a nitrogen layer on Pt(111) at room temperature to determine the effects of pressure on the ability to achieve a higher coverage of NH than what can be achieved under UHV conditions. A detailed discussion about the system limitations are provided and possible improvements are suggested.en_US
dc.language.isoenen_US
dc.rightsen_US
dc.rightsCopyright 2011 Jun Yinen_US
dc.subjectNOx storage-reductionen_US
dc.subjectPhysical vapor depositionen_US
dc.subjectReflection absorption infrared spectroscopyen_US
dc.subjectSelective catalytic reductionen_US
dc.subjectScanning tunneling microcopyen_US
dc.subjectTemperature programmed desorptionen_US
dc.subjectPt(111)en_US
dc.subjectQuadruple mass spectrometryen_US
dc.subjectUltrahigh vacuumen_US
dc.subjectsurface scienceen_US
dc.subjectAuger electron spectroscopyen_US
dc.subjectInfrared reflection absorption spectroscopyen_US
dc.subjectLow energy electron diffractionen_US
dc.subjectLangmuiren_US
dc.titleFundamental Studies of Nitrogen and Hydrocarbons on Metal Surfacesen_US
thesis.degree.departmentChemical Engineeringen_US
thesis.degree.disciplineChemical Engineeringen_US
thesis.degree.grantorUniversity of Illinois at Chicagoen_US
thesis.degree.levelDoctoralen_US
thesis.degree.namePhD, Doctor of Philosophyen_US
dc.type.genrethesisen_US
dc.contributor.committeeMemberTrenary, Michaelen_US
dc.contributor.committeeMemberChan, Allyen_US
dc.contributor.committeeMemberKlie, Roberten_US
dc.type.materialtexten_US


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