is an emissions control device, incorporated into an
automobile’s exhaust system, containing catalysts
— such as platinum, palladium, or rhodium — that reduce the levels of
hydrocarbons (HC),
carbon monoxide (CO) and
nitrogen oxides (NOx) emitted to
the air. In the catalytic converter, HC and CO are oxidized to form carbon
dioxide (CO2), and NOx are reduced to nitrogen and
oxygen. Three-way catalytic converters that control all three substances
require associated electronic controls for precise regulation of oxygen
levels in the exhaust gas. Catalytic converters are also effective in
removing PNA (polynuclear aromatic) hydrocarbons. Cars equipped with
catalytic converters require unleaded
gasoline, since the lead in tetraethyl lead, an
antiknock compound, is a catalyst
"poison".
Also see emissions
(automotive), hydrocarbon
emissions, pollutants,
lead alkyl.