Catalytic converters reduce poisonous vehicle emissions of carbon monoxide, nitrogen oxides and hydrocarbons, which improves air quality and reduces environmental damage. To convert the harmful gases, the catalytic converter uses precious metals to generate a chemical reaction, including platinum, palladium and rhodium for the catalyst, making them expensive to produce.
The catalyst is used to coat a ceramic honeycomb, or ceramic beads, in a muffler-like package that is attached to the vehicle's exhaust system. The precious metals convert carbon monoxide and hydrocarbons into carbon dioxide and water, while separating nitrogen oxides back into nitrogen and oxygen. Because the precious metals used are a limited natural resource some manufacturers are blending in more common metals, such as aluminum and cerium, to reduce the amount needed to achieve the same catalytic reaction.