A standard commercial three-way catalyst was aged at 950°C for 24 hours in dry N2 with 2% O2. The performance of the aged and a fresh samples were characterized using a synthetic exhaust flow system.The light-off temperature for all three pollutants on the aged sample was more than 70°C higher than for the fresh one. The effect of aging on steady-state performance at higher temperatures (>400°C) was more moderate.In order to explain the decrease in activity the samples were analysed for their bulk and surface composition using electron microscopy (TEM/STEM/EDS), photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). In addition the precious metal dispersion were determined by CO chemisorption and the total area by standard BET measurement.TEM micrographs showed that the metal particles containing platinum had an average diameter between 3-4 nm in the fresh sample but grow considerably in size upon aging. Very large sintered platinum particles (>1μm) were occasionally observed in the aged sample. The Pt/Rh ratio in these particles measured by STEM/EDS was twice as high on the aged catalyst compared to the fresh one, presumably due to a higher surface mobility for platinum. XPS measurements showed a higher degree of rhodium oxidation in the aged sample.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Thermal Deactivation of a Three-Way Catalyst: Changes of Structural and Performance Properties


    Weitere Titelangaben:

    Sae Technical Papers


    Beteiligte:
    Stenbom, Bertil (Autor:in) / Wirmark, Goran (Autor:in) / Smedler, Gudmund (Autor:in) / Nilsson, Per H (Autor:in) / Lundgren, Staffan (Autor:in)

    Kongress:

    International Congress & Exposition ; 1990



    Erscheinungsdatum :

    1990-02-01




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Thermal deactivation of three-way catalyst:changes of structural and performance properties

    Stenbom,B. / Smedler,G. / Nilsson,P.H. et al. | Kraftfahrwesen | 1990


    Thermal effect on three-way catalyst deactivation and improvement

    Ihara,K. / Ohkubo,K. / Niura,Y. et al. | Kraftfahrwesen | 1987


    A Study on Three Way Conversion Catalyst Thermal Deactivation and improvement

    Funabiki, Masaki / Yamada, Teiji | SAE Technical Papers | 1988


    High Temperature Deactivation of Three-Way Catalyst

    Mann, G. S. / Carol, L. A. / Newman, N. E. | SAE Technical Papers | 1989


    A study on three way conversion catalyst thermal deactivation and improvement

    Funabiki,M. / Yamada,T. / Nippon Engelhard,JP | Kraftfahrwesen | 1988