Eco Technology: Catalytic converter

A catalytic converter (CAT) is a device made up of a very thin layer of platinum group metals on a honeycomb structure which treats the exhaust before it leaves the vehicle, so removing a lot of the pollution.

All new cars sold in Britain since January 1993 onwards equipped with three-way catalytic converters. "Three-way" refers to the three regulated emissions it helps to reduce - carbon monoxide, un-burnt hydrocarbons and nitrogen oxide molecules.  The use of catalytic converters has lead to a substantial reduction in the emissions of these pollutants, however, they cause an increase in carbon dioxide (CO2) emissions. This does not cause a problem for air quality, but is considered to contribute to global warming.

Catalytic converters work at their best at relatively high engine temperatures. When starting the engine from cold the cat does almost nothing to reduce the poisoness emissions. Electric/Fuel Hybrid cars that have big, high-voltage battery packs can provide enough power to heat up the catalytic converter very quickly which contributes to their green claims of lower emissions.