A laboratory study was performed to optimize a zoned configuration of an iron (Fe) SCR catalyst and a copper (Cu) SCR catalyst in order to provide high NOx conversion at lean A/F ratios over a broad range of temperature for diesel and lean-burn gasoline applications. With an optimized space velocity of 8,300 hr-1, a 67% (by volume) Fe section followed by a 33% Cu section provided at least 80% NOx conversion from approximately 230°C to 640°C when evaluated with 500 ppm NO and NH3. To improve the lean lightoff performance of the SCR catalyst system during a cold start, a Cu SCR catalyst that was 1/4 as long as the rear Cu SCR catalyst was placed in front of the Fe SCR catalyst. When evaluated with an excess of NH3 (NH3/NO ratio of 2.2), the Cu+Fe+Cu SCR system had significantly improved lightoff performance relative to the Fe+Cu SCR system, although the front Cu SCR catalyst did decrease the NOx conversion at temperatures above 475°C by oxidizing some of the NH3 to N2 or NO.


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    Title :

    SCR Catalyst Systems Optimized for Lightoff and Steady-State Performance


    Additional title:

    Sae Int. J. Fuels Lubr
    Sae International Journal of Fuels and Lubricants


    Contributors:

    Conference:

    SAE World Congress & Exhibition ; 2009



    Publication date :

    2009-04-20


    Size :

    10 pages




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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