Catalytic Converter: Description and Operation

Three-Way Catalytic Converter:

CONSTRUCTION
The TWC contains a catalyst in the form of a specially treated honeycomb structure saturated with catalytically active precious metals (either platinum and rhodium, or palladium and rhodium).

OPERATION

The Engine Exhaust and Harmful Pollutants
The catalytic converter and exhaust systems work together to control the release of harmful engine exhaust emissions into the atmosphere. The engine exhaust gas consists mainly of nitrogen, carbon dioxide and water vapor. However, it also contains carbon monoxide, oxides of nitrogen, hydrogen, and various unburned hydrocarbons, which are major air pollutants and their emission into the atmosphere has to be controlled.

How The Three Way Catalytic (TWC) Converter Works
A catalyst is a material that remains unchanged when it initiates and increases the speed of a chemical reaction. A catalyst will also enable a chemical reaction to occur at a lower temperature. The TWC catalyzes the oxidation reactions of unburned hydrocarbons and carbon monoxide and the reduction reaction of oxides of nitrogen. This three-way conversion only occurs when the air/fuel ratio is near stoichiometry.