More than 90% of new passenger vehicles - cars, vans and light trucks - are now fitted with catalysts, one third of which have been supplied by Johnson Matthey.
The catalyst sits in the exhaust system, either near to the engine (close-coupled), or further down the tailpipe (underfloor).
Harmful gases are converted to harmless products in a reaction with the catalyst which contains precious metals.
Three-way catalyst (TWC)
Gasoline or petrol fuelled vehicles typically use a three-way catalyst (TWC), so-called because it converts three pollutants:
- Carbon monoxide (CO)
- Hydrocarbons (HC)
- Oxides of nitrogen (NOx)
- to carbon dioxide, water and nitrogen.
Conversion rates of over 90% are possible.
Diesel oxidation catalyst (DOC)
Diesel engines require a diesel oxidation catalyst (DOC) to remove CO and HC and can also reduce particulate matter (PM) by up to 50%.
More effective PM removal is achieved with diesel particulate filter (DPF) systems.
For further information please contact us.