Purification of Exhaust Gases. Removal of pollutants from exhaust gas after they leave the engine cylinder can be done either by using a thermal reactor or by using a catalytic converter
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Purification of Exhaust Gases
Removal of pollutants from exhaust
gas after they leave the engine cylinder can be done either by using a thermal reactor or by using a catalytic converter
In order to oxidize HC in the gas phase without catalyst a residence time of the order of 50ms and temp of about 6000 C is required.
Whereas to oxidize CO temp in excess of 7000C is required.
Four basic designs have been developed
Washcoat is applied to substrate material. It has a surface area of 100-200 m2/g.
Conversion efficiency =
(min – mout)/min = 1 – mout/min
Conversion efficiency of a new catalytic converter is 98 – 99 % for CO and 95% for HC
Light off temperature of a catalytic converter is the temperature at which the catalytic converter become 50% effective.
Typical light off temperature is 250 -3000 C