The 1975 federal CVS test procedure and emission standards have placed a heavy emphasis on minimizing the time required after engine start up to begin converting exhaust emissions. Four major improvements in catalytic HC/CO converters have been made in the past year to reduce catalyst ignition time: Small laboratory samples of potential HC/CO oxidation catalysts were screened for activity in a “laboratory simulated cold-start” test with exhaust from a 2-cyl engine. Several improved catalyst candidates were evaluated in a full-size converter “cold-start” test with exhaust from a 351 in3 engine.Locating the converters closer to the exhaust manifold results in higher catalyst operating temperatures which require greater stability at high temperatures in the presence of trace contaminants. Stability, when exposed to wide temperature variations and changes from oxidation to reduction environments, has been evaluated in a thermal-cycling test for several improved catalysts. Catalyst stability to long-term exposure has also been evaluated in an engine dynamometer mileage accumulation test operated under simulated road conditions.Unfortunately, the rapid thermal-chemical response of the improved catalyst, operated closer to the exhaust manifold, increases the occurrences of excessive catalyst temperatures. Mathematical model studies of the effect of the improved catalyst properties on thermal response indicate a need to prevent unexpected high CO or HC concentration peaks in the engine exhaust, or to improve properties of existing catalysts. System changes, such as moving the low temperature catalyst farther from the exhaust manifold, may be required to obtain some protection from catalyst overtemperatures. These changes increase emission levels and require a breakthrough in engine control of raw emissions or improved catalysts.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Status Report on HC/CO Oxidation Catalysts for Exhaust Emission Control


    Weitere Titelangaben:

    Sae Technical Papers


    Beteiligte:
    Lassen, H. G. (Autor:in) / Snyder, P. W. (Autor:in) / Stover, W. A. (Autor:in)

    Kongress:

    National Automobile Engineering Meeting ; 1972



    Erscheinungsdatum :

    01.02.1972




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    HC/CO Oxidation Catalysts for Vehicle Exhaust Emission Control

    Dwyer, F. G. / Jagel, K. I. | SAE Technical Papers | 1971


    Design of Oxide Catalysts for Exhaust Emission Control

    Uemura, K. / Nagai, T. / Kimura, M. et al. | British Library Conference Proceedings | 2008


    Formaldehyde Oxidation over Emission Control Catalysts

    Bertole, Christopher | British Library Conference Proceedings | 2018


    Formaldehyde Oxidation over Emission Control Catalysts

    Bertole, Christopher | SAE Technical Papers | 2018


    Heavy duty emission control using oxidation catalysts

    Leyrer,J / Lox,E. / Osrgathe,K. et al. | Kraftfahrwesen | 1991