Catalytic converter

Emissions control device, incorporated into an automobile’s exhaust system, that reduce the levels of hydrocarbons (HC), carbon monoxide (CO), and - in more recent designs - nitrogen oxides (NOx) emitted to the air by gasoline-powered vehicle engines.

Catalytic converters do not help reducing emissions during the first minutes after cold-start, as they need a high temperature to operate.

Source: GreenFacts

Deutsch: Katalysator
Español: Catalizador
Français: Convertisseur catalytique