The catalytic converter is located in the exhaust system, and exhaust gases flow through it before being released to the atmosphere.
The heart of the catalytic converter is a ceramic monolith. This is a honeycombed structure that has many small channels through which the exhaust gases flow.
The entire surface of the monolith is coated with a washcoat of aluminium oxide. This enlarged surface is then coated again with the precious metals platinum and rhodium or palladium and rhodium in a ratio of 5:1. This creates reaction surfaces for oxidation, i.e. reduction, of the exhaust pollutants.
There may be several monoliths in the catalytic converter to compensate for expansion due to the high exhaust gas temperatures.
The pressure-sensitive monoliths are provided with an elastic intermediate layer in a two-shell, thermally insulated stainless steel casing.
A specific operating temperature is necessary for the catalytic converter to function correctly.