Catalytic Converter: Description and Operation

Catalytic Converter System - AT-PZEV (SULEV) model

The TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to carbon dioxide (CO2), nitrogen (N2), and water vapor (H2O).

Catalytic Converter System - ULEV model




Three Way Catalytic Converter (TWC)
The TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to carbon dioxide (CO2), nitrogen (N2), and water vapor (H2O).




NOx Adsorptive Three Way Catalyst (NOx Adsorptive TWC)
The NOx adsorptive TWC absorbs NOx created during lean burn running when the oxygen concentration is high. Then the engine is put into a richer running mode where the oxygen concentration and NOx levels are low, and the absorbed NOx is released, keeping the average NOx emissions low.