Catalytic Converter: Description and Operation

Three Way Catalytic Converter (TWC):

Three Way Catalytic Converter (TWC) System
The engine exhaust consists mainly of Nitrogen (N2); however, it also contains Carbon Monoxide (CO), Carbon Dioxide (CO2), Water Vapor (H2O), Oxygen (O2), Nitrogen Oxides (NOx), and Hydrogen (H2) as well as various unburned Hydrocarbons (HC). Three of these exhaust components - CO, NOx, and HC - are major air pollutants, so their emission to the atmosphere must be controlled.

The Three Way Catalytic Converter (TWC), mounted in the engine exhaust system, works as a gas reactor to convert and reduce the pollutant levels to within legally prescribed limits.

The TWC reduces the air pollutants HC, CO, and NOx. The TWC removes these pollutants from the exhaust gases by means of a chemical reaction. The remaining gases are transferred to the muffler.

The catalyst metals are thinly coated onto and supported by a honeycomb shaped high temperature ceramic mounted inside the converter shell. The result is a highly effective converter design having minimum restriction to exhaust gas flow and good durability.





Warm Up Three Way Catalytic Converter
The Warm Up Three Way Catalytic Converter (WU-TWC) is designed to reduce HC, CO, and NOx during warm up conditions.

The WU-TWC is mounted ahead of the TWC, causing it to warm up faster upon vehicle start up. This results in less air pollutants escaping during warm up.