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dc.contributor.advisorÖzensoy, Emrah
dc.contributor.authorSay, Zafer
dc.date.accessioned2016-01-08T19:41:34Z
dc.date.available2016-01-08T19:41:34Z
dc.date.issued2011
dc.identifier.urihttp://hdl.handle.net/11693/16158
dc.descriptionAnkara : The Department of Chemistry and the Graduate School of Engineering and Science of Bilkent University, 2011.en_US
dc.descriptionThesis (Master's) -- Bilkent University, 2011.en_US
dc.descriptionIncludes bibliographical references leaves 56-62.en_US
dc.description.abstractIn the current work, the effect of CeO2 promotion on the NOx storage materials and NOx storage-reduction (NSR) catalysts is studied. Synthesized materials were prepared using different baria and ceria loadings in order to investigate the influence of the surface composition on the NOx storage process. Synthesized materials were also thermally treated in the temperature range within 300 - 1273 K to mimic the thermal aging effects on the material structure. Structural properties of the synthesized materials were investigated via spectroscopic and diffraction techniques such as Raman spectroscopy, X-ray diffraction (XRD), and BET (Brunauer, Emmett, ve Teller) surface area analysis. These ex-situ characterization studies revealed that materials containing Pt showed indications of sintering after thermal treatment at elevated temperatures where Pt sites grew in size and were partially covered by BaO domains. Pt addition to the BaO/Al2O3 system facilitated the formation of the undesired BaAl2O4 phase, particularly at high baria loadings. Decomposition of the Ba(NO3)2 species took place at lower temperatures for Pt containing materials. An indication for a strong-metal-support interaction (SMSI) between Pt and CeO2 sites was observed in Raman spectroscopic data, resulting in the formation of a new mixed oxide phase on the surface. BET results indicated that the specific surface area (SSA) of the synthesized materials monotonically decreased with increasing temperature and increasing BaO and CeO2 loadings. The behavior of the synthesized materials in NOx and SOx adsorption experiments were also investigated via temperature programmed desorption (TPD) and in-situ Fourier transform infrared (FTIR) spectroscopy. Ceria promotion had no significant influence on the nature of the adsorbed nitrate species and the NOx uptake ability of the alumina support material. On the other hand, addition of Pt to CeO2/Al2O3 binary and BaO/CeO2/Al2O3 ternary systems was observed to enhance the NOx storage. For the ternary mixed oxide NOx storage systems (BaO/CeO2/Al2O3), increasing BaO or CeO2 loadings results in a decrease in the specific surface area values, which in turn leads to decreasing NOx uptake. SO2 (g) + O2 (g) interaction with a selected set of samples were also investigated via in-situ FTIR spectroscopy. These experiments reveal that ceria promotion and platinum addition assisted the formation of surface sulfate species. Furthermore, the presence of ceria also resulted in a decrease in the thermal stability of sulfates and enabled easier regeneration.en_US
dc.description.statementofresponsibilitySay, Zaferen_US
dc.format.extentxiii, 63 leavesen_US
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectNSRen_US
dc.subjectNOx storage materialsen_US
dc.subjecty-Al2O3en_US
dc.subjectCe/Alen_US
dc.subjectPt/Ce/Alen_US
dc.subjectBa/Ce/Alen_US
dc.subjectBa/Pt/Ce/Alen_US
dc.subjectSOx poisoningen_US
dc.subjectXRDen_US
dc.subjectRamanen_US
dc.subjectBETen_US
dc.subjectFTIR spectroscopyen_US
dc.subjectTPDen_US
dc.subjectXPSen_US
dc.subject.lccQD181.N1 S39 2011en_US
dc.subject.lcshNitrogene oxides.en_US
dc.subject.lcshOxidation.en_US
dc.subject.lcshCatalysis.en_US
dc.titleCeria promoted NOx storage and reduction materialsen_US
dc.typeThesisen_US
dc.departmentDepartment of Chemistryen_US
dc.publisherBilkent Universityen_US
dc.description.degreeM.S.en_US
dc.identifier.itemidB130540


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