Catalytic Converters for Reduction of Car Engine Emissions

Secondary measures to reduce exhaust emissions of cars, so-called end-of-pipe solutions, are based on the catalytic conversion of all three harmful emissions  

About 500 mio. cars (out of about 1 billion in total in 2011) are worldwide equipped with such a catalytic converter. Although the concentrations of CO, HCs, and of NO are small (Table 6.18.1), the overall consumption rates are high 40 mio. tonnes CO, 10 mio. tonnes HCs, and 15 mio. tonnes NO (Votsmeier, 2012). 

The success of the catalytic converter is up to now mainly limited to gasoline powered engines. However, in recent years progress has also been made in the development of catalytic filters for the cleaning of exhaust gas (e.g., particulate matter) from diesel engines. 

Obviously, one reactor for the treatment of all three pollutants is preferable, but the oxidation of HCs and CO requires an oxidizing atmosphere and the conversion of NOjc a reducing one. Thus in a simple one-reactor approach only CO and HC or NOjc are converted almost completely or a compromise has to be found to convert at least a main proportion of all three pollutants simultaneously. 

Catalyst honey comb substrate permeated with precious metals 

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