Catalytic Converters

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					Catalytic Converters
Catalytic Converters
   Catalytic converters are heterogeneous catalysts
   Function:
     Oxidizes CO and unburned hydrocarbons to
       CO2 and H2O
     Reduction of NO to N2



       SMOG – CO and NO
Design of a Converter
   Must be able to function over a wide range of
    temperatures
   Must continue to be active despite the additives in
    gasoline
   Must be rugged in design
CO and NO Conversion
   Use metal oxides (CuO and Cr2O3) and noble
    metals such as platinum
   These are supported in either a bead or honeycomb
    structure made from alumina, Al2O3
     Adsorbs O2 gas from exhaust, weaken O2 bond
        and allows them to react with CO to form CO2

                           Ceramic


                   Steel
Benefits
   Great heterogeneous catalysts
   Gases are only in contact with catalyst for 100 to
    400 ms, but…
   96% of hydrocarbons and CO are converted to CO2
    and H2O
   NO emission is cut to 76%
   Use expensive metals (more $$ than gold) platinum
    and rhodium which have been stolen by thieves and
    sold for $$!

				
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posted:8/7/2012
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