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.

Johnson Matthey products are fitted to about a third of all cars produced worldwide

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.