Advanced ceramics have
high strength, can survive high temperatures, are chemically inert
and light. These properties make them excellent in the production
of filters for exhaust fumes.
Exhaust filters become blocked by the carbon particles,
so they need to be replaced regularly. This makes them unsuitable
for many vehivles but Johnson Matthey have developed a filter
that can clean itself.
Exhaust gases pass over a platinum catalyst which
converts Nitrogen monoxide into Nitrogen dioxide. Particulates
are filtered out by a ceramic honeycombe. When the temperature
of the exhaust rises over 250oC, the Nitrogen dioxide
allows the carbon particles to burn off and regenerate a clean
out of a
of the exhaust
up to 90%
of the PM10's.
48 to 20
European limits on PM10's
Particulate filters will help vehicles to meet
the increasingly tough emissions regulations and clean up
the air in our cities.