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Kwak, Ja Hun
Molecular Catalysis lab
Research Interests
  • Heterogeneous catalysis, molecular catalysis, ASlumima, zeolites


Changes in ba phases in BaO/Al2O3 upon thermal aging and H2O treatment

DC Field Value Language Kim, Do Heui ko Chin, Ya-Huei ko Kwak, Jahun ko Szanyi, Janos ko Peden, Charles H.F ko 2015-07-16T00:42:30Z - 2015-07-15 ko 2005-12 -
dc.identifier.citation CATALYSIS LETTERS, v.105, no.3-4, pp.259 - 268 ko
dc.identifier.issn 1011-372X ko
dc.identifier.uri -
dc.identifier.uri ko
dc.description.abstract The effects of thermal aging and H2O treatment on the physicochemical properties of BaO/Al2O3 (the NOx storage component in the lean NOx trap systems) were investigated by means of X-ray diffraction (XRD), BET, TEM/EDX and NO2 TPD. Thermal aging at 1000 degrees C for 10 h converted dispersed BaO/BaCO3 on Al2O3 into low surface area crystalline BaAl2O4. TEM/EDX and XRD analysis showed that H2O treatment at room temperature facilitated a dissolution/reprecipitation process, resulting in the formation of a highly crystalline BaCO3 phase segregated from the Al2O3 support. Crystalline BaCO3 was formed from conversion of both BaAl2O4 and a dispersed BaO/BaCO3 phase, initially present on the Al2O3 support material after calcinations at 1000 and 500 degrees C, respectively. Such a phase change proceeded rapidly for dispersed BaO/BaCO3/Al2O3 samples calcined at relatively low temperatures with large BaCO3 crystallites observed in XRD within 10 min after contacting the sample with water. Significantly, we also find that the change in barium phase occurs even at room temperature in an ambient atmosphere by contact of the sample with moisture in the air, although the rate is relatively slow. These phenomena imply that special care to prevent the water contact must be taken during catalyst synthesis/storage, and during realistic operation of Pt/BaO/Al2O3 NOx trap catalysts since both processes involve potential exposure of the material to CO2 and liquid and/or vapor H2O. Based on the results, a model that describes the behavior of Ba-containing species upon thermal aging and H2O treatment is proposed ko
dc.description.statementofresponsibility close -
dc.language ENG ko
dc.publisher SPRINGER ko
dc.subject BaO/Al2O3 ko
dc.subject BaAl2O4 ko
dc.subject lean NOx trap ko
dc.subject NO2 TPD ko
dc.subject NOx storage ko
dc.subject nitric oxide ko
dc.title Changes in ba phases in BaO/Al2O3 upon thermal aging and H2O treatment ko
dc.title.alternative Changes in ba phases in BaO/Al2O3 upon thermal aging and H2O treatment ko
dc.type ARTICLE ko
dc.identifier.scopusid 2-s2.0-27844534891 ko
dc.identifier.wosid 000233351300020 ko
dc.type.rims ART ko
dc.description.wostc 30 *
dc.description.scopustc 35 * 2015-12-28 * 2015-11-04 *
dc.identifier.doi 10.1007/s10562-005-8700-y ko
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