What is a Catalytic Converter?

A catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds. The three harmful compounds are: hydrocarbons, carbon monoxide, and nitrogen oxides. Carbon monoxide is a poison for any air-breathing animal. Nitrogen oxides lead to smog and acid rain, and hydrocarbons produce smog. The catalyst helps to convert carbon monoxide into carbon dioxide, the hydrocarbons into carbon dioxide and water, and the nitrogen oxides back into nitrogen and oxygen.

Source: How It Works