Catalytic Converter

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The catalytic converter reduces the carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx) content of the exhaust gases. In the catalytic converter the exhaust gases pass through honeycombed ceramic elements whose surface is treated with a special deposit of washcoat containing catalytic elements. The washcoat also increases the surface area of the ceramic elements by a factor of approximately 7, 000.

The palladium and rhodium are on the surface of the washcoat. The palladium facilitates the oxidation of HC and CO to form water vapor (H2O) and carbon dioxide (CO2). The rhodium facilitates the reduction of the NOx into molecular Nitrogen (N2) by extraction of the O2 from the NOx molecules. The chemical process of Oxidation of CO, HC and reduction of NOx occurs according to the level of oxygen in the exhaust flow. Maximum efficiency (best CO/hydrocarbons oxidation, best NOx reduction) occurs at Lambda 1.

For additional information, refer to: ELECTRONIC ENGINE CONTROLS