What is an Autocatalyst?
An autocatalyst is a cylinder of circular or elliptical cross
section made from ceramic or metal formed into a fine honeycomb and
coated with a solution of chemicals and platinum group metals. It
is mounted inside a stainless steel canister (the whole assembly is
called a catalytic converter) and is installed in the exhaust line
of the vehicle between the engine and the silencer (muffler).
How do autocatalysts help the environment?
Vehicle exhaust contains a number of harmful elements which can
be controlled by the platinum group metals in autocatalysts. The
major exhaust pollutants are:
- carbon monoxide, which is a poisonous gas
- oxides of nitrogen, which contribute to acid rain, low
level ozone and smog formation and which exacerbate
- hydrocarbons, which are involved in the formation of smog and
have an unpleasant smell
- particulate, which contains known cancer-causing compounds
Autocatalysts convert over 90 per cent of hydrocarbons, carbon
monoxide and oxides of nitrogen from gasoline engines into less
harmful carbon dioxide, nitrogen and water vapour. Autocatalysts
also reduce the pollutants in diesel exhaust by converting over 90
per cent of hydrocarbons, carbon monoxide and particulate matter
into carbon dioxide and water vapour.
A brief history of pollution controls
In 1975 the United States, following the lead of the Californian
Air Resources Board, and Japan applied clean air legislation which
led to autocatalysts being fitted to light duty vehicles. Many
other countries with large vehicle markets have followed since
then, including South Korea (1987), Mexico (1989), the member
states of the European Union (1993), Brazil (1994), Russia (1999)
and China and India (2000). Today, over 95 per cent of all new
vehicles sold globally each year are fitted with catalytic
Autocatalysts in the future
As the number of cars on the road increases, further cuts in
pollution per vehicle are needed to keep improving air quality.
Many governments, including those of the USA, Japan and the EU
continue to apply increasingly stricter emissions
standards. Advanced autocatalysts for gasoline and diesel cars and
heavy trucks are being developed by Johnson Matthey in partnership
with the world automotive industry to meet the new rules. In many
cases these will lead to greater use of the catalyst metals
platinum, palladium and rhodium.
Autocatalyst demand for platinum, palladium and rhodium is
estimated in our market data tables.