Cobalt supported on zirconia and sulfated zirconia I. FT-IR spectroscopic characterization of the NOx species formed upon NO adsorption and NO/O2 coadsorption

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dc.citation.epage363en_US
dc.citation.issueNumber2en_US
dc.citation.spage352en_US
dc.citation.volumeNumber223en_US
dc.contributor.authorKantcheva, M.en_US
dc.contributor.authorVakkasoglu, A. S.en_US
dc.date.accessioned2016-02-08T10:27:14Z
dc.date.available2016-02-08T10:27:14Z
dc.date.issued2004en_US
dc.departmentDepartment of Chemistryen_US
dc.description.abstractCobalt catalysts are prepared by impregnating zirconia and sulfated zirconia using an aqueous solution of cobalt(II) acetate. XRD results show that the catalysts with 5 wt% cobalt loading contain a small amount of Co 3O4. Analysis of the FT-IR results on the adsorption of NO at room temperature reveals the formation of cobalt(II) mono- and dinitrosyls. It is shown that the nitrosyls formed on the sulfate-free catalyst with 5 wt% cobalt loading are unstable on prolonged contact with NO at room temperature due to the oxidation of adsorbed NO to NO2 - (nitro) and NO3 - species by cobalt(III) originating from the Co3O4 phase. This process does not occur in the case of the sulfated catalyst containing the same amount of cobalt, for which the existence of a Co3O4 phase is also detected. This experimental fact leads to the conclusion that the sulfate ions lower the reducibility of cobalt(III). Upon coadsorption of NO and O2 at room temperature on the samples studied, various kinds of surface nitrates are observed differing in the modes of their coordination. In the case of CoO x/SO4 2--ZrO2 catalysts, part of the bidentate nitrates transform to NO2 - (nitro) species after evacuation at 373 K. The nitro-nitrato species on the sulfated catalysts are characterized by a lower thermal stability than that of the nitrates on the CoOx/ZrO2 samples. © 2004 Elsevier Inc. All rights reserved.en_US
dc.description.provenanceMade available in DSpace on 2016-02-08T10:27:14Z (GMT). No. of bitstreams: 1 bilkent-research-paper.pdf: 70227 bytes, checksum: 26e812c6f5156f83f0e77b261a471b5a (MD5) Previous issue date: 2004en
dc.identifier.doi10.1016/j.jcat.2004.02.007en_US
dc.identifier.issn0021-9517
dc.identifier.urihttp://hdl.handle.net/11693/24296
dc.language.isoEnglishen_US
dc.publisherAcademic Pressen_US
dc.relation.isversionofhttp://dx.doi.org/10.1016/j.jcat.2004.02.007en_US
dc.source.titleJournal of Catalysisen_US
dc.subjectAdsorption of NO and NO/O2en_US
dc.subjectCoOx/ZrO2en_US
dc.subjectCoOx/ZrO2 - SO4 2-en_US
dc.subjectIn situ FT - IRen_US
dc.titleCobalt supported on zirconia and sulfated zirconia I. FT-IR spectroscopic characterization of the NOx species formed upon NO adsorption and NO/O2 coadsorptionen_US
dc.typeArticleen_US

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