Fe promoted NOx storage materials: structural properties and NOx uptake

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dc.citation.epage369en_US
dc.citation.issueNumber1en_US
dc.citation.spage357en_US
dc.citation.volumeNumber114en_US
dc.contributor.authorKayhan, E.en_US
dc.contributor.authorAndonova, S. M.en_US
dc.contributor.authorŞentürk, G. S.en_US
dc.contributor.authorChusuei, C. C.en_US
dc.contributor.authorOzensoy, E.en_US
dc.date.accessioned2016-02-08T10:00:26Z
dc.date.available2016-02-08T10:00:26Z
dc.date.issued2010en_US
dc.departmentDepartment of Chemistryen_US
dc.departmentInstitute of Materials Science and Nanotechnology (UNAM)en_US
dc.description.abstractFe promoted NOx storage materials were synthesized in the form of FeOx/BaO/Al2O3 ternary oxides with varying BaO (8 and 20 wt %) and Fe (5 and 10 wt %) contents. Synthesized NOx storage materials were investigated via TEM, EELS, BET, FTIR, TPD, XRD, XPS, and Raman spectroscopy, and the results were compared with the conventional BaO/Al2O3 NOx storage system. Our results suggest that the introduction of Fe in the BaO/Al2O3 system leads to the formation of additional NOx storage sites which store NOx mostly in the form of bidentate nitrates. NO2 adsorption experiments at 323 K via FTIR indicate that, particularly in the early stages of the NOx uptake, the NOx storage mechanism is significantly altered in the presence of Fe sites where a set of new surface nitrosyl and nitrite groups were detected on the Fe sites and the surface oxidation of nitrites to nitrates is significantly hindered with respect to the BaO/Al2O3 system. Evidence for the existence of both Fe3+ as well as reduced Fe2+/(3-x)+ sites on the freshly pretreated materials was detected via EELS, FTIR, Raman, and XRD experiments. The influence of the Fe sites on the structural properties of the synthesized materials was also studied by performing ex situ annealing protocols within 323-1273 K followed by XRD and Raman experiments where the temperature dependent changes in the morphology and the composition of the surface domains were analyzed in detail. On the basis of the TPD data, it was found that the relative stability of the stored NOx species is influenced by the morphology of the Ba and Fe containing NOx-storage domains. The relative stabilities of the investigated NOx species were found to increase in the following order: N2O3/NO+ < nitrates on γ-Al2O3 < surface nitrates on BaO < bidentate nitrates on FeOx sites < bulk nitrates on BaO.en_US
dc.identifier.doi10.1021/jp907982qen_US
dc.identifier.eissn1932-7455
dc.identifier.issn1932-7447
dc.identifier.urihttp://hdl.handle.net/11693/22460
dc.language.isoEnglishen_US
dc.publisherAmerican Chemical Societyen_US
dc.relation.isversionofhttp://dx.doi.org/10.1021/jp907982qen_US
dc.source.titleJournal of Physical Chemistry Cen_US
dc.subjectAdsorption experimenten_US
dc.subjectEx-situ annealingen_US
dc.subjectFTIRen_US
dc.subjectRaman experimentsen_US
dc.subjectRelative stabilitiesen_US
dc.subjectStorage mechanismen_US
dc.subjectStorage sitesen_US
dc.subjectStorage systemsen_US
dc.subjectSurface domainsen_US
dc.subjectSurface nitratesen_US
dc.subjectSurface oxidationsen_US
dc.subjectSynthesized materialsen_US
dc.subjectTEMen_US
dc.subjectTemperature-dependent changesen_US
dc.subjectTernary oxidesen_US
dc.subjectXPSen_US
dc.subjectXRDen_US
dc.subjectAdsorptionen_US
dc.subjectBariumen_US
dc.subjectExperimentsen_US
dc.subjectFourier transform infrared spectroscopyen_US
dc.subjectIron oxidesen_US
dc.subjectMaterials propertiesen_US
dc.subjectMorphologyen_US
dc.subjectNitratesen_US
dc.subjectRaman spectroscopyen_US
dc.subjectStorage (materials)en_US
dc.subjectStructural propertiesen_US
dc.subjectSystem stabilityen_US
dc.subjectX ray diffractionen_US
dc.subjectSurfacesen_US
dc.titleFe promoted NOx storage materials: structural properties and NOx uptakeen_US
dc.typeArticleen_US

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Department of Chemistry
Institute of Materials Science and Nanotechnology (UNAM)