Johnson Matthey - Cars, Vans and Light Trucks
More than 90% of new passenger vehicles are now fitted with autocatalysts, 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 precious metal-containing catalyst.
Gasoline or petrol fuelled vehicles typically use a 3-way catalyst, so-called because it converts 3 pollutants, carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NOx) to carbon dioxide, water and nitrogen. Conversion rates of over 90% are possible.
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.