What is the function of a catalytic converter?

A catalytic converter reduces harmful exhaust emissions by promoting chemical reactions that convert pollutants into less harmful substances. Three-way catalytic converters use precious metal catalysts (platinum, palladium, rhodium) to simultaneously oxidize carbon monoxide and unburnt hydrocarbons into CO2 and water, while reducing nitrogen oxides into nitrogen and oxygen. They require operating temperatures of 400-800°C for optimal efficiency.