About Catalytic Converters

Catalytic converters are vehicle exhaust emissions components designed to reduce emissions by re-burning engine exhaust as it flows through a vehicle's exhaust system. Very similar in shape and design to a vehicle muffler, catalytic converters greatly reduce vehicle exhaust emissions and promote cleaner air. Catalytic converters have been standard-issue equipment on American cars since 1975.

History

Catalytic converters are special types of vehicle exhaust "afterburners" responsible for igniting and burning unburned vehicle engine exhaust gases. Catalytic converters were made mandatory in 1975 when cars started using unleaded gasoline. Vehicles equipped with catalytic converters require unleaded gasoline, a much cleaner burning fuel than leaded gasoline.

Significance

Vehicle engine combustion is not an exact science. Small amounts of unburned engine fuel are emitted from a vehicle's engine exhaust. This unburned fuel is highly toxic to the environment and is a major contributor to poor air quality. After passing through a catalytic converter, engine exhaust gases are significantly cleaner.

Function

Catalytic converters bolt directly to a vehicle's exhaust pipe, roughly midway between the vehicle exhaust manifold and vehicle tailpipe. A vehicle's exhaust pipe funnels exhaust gases directly through the inner chamber of a catalytic converter, which is filled with small charcoal-like nuggets called catalyst material, which are highly reactive, heat-sensitive pellets that become super heated in response to incoming exhaust gases. This catalyst material is what ignites and burns the unburned gas content contained in vehicle exhaust.

Benefits

By reducing the amount of unburned gasoline that exits automotive tail pipes, thus reducing hydrocarbon emissions, which are a main component of photochemical smog, catalytic converters have contributed greatly to improved air quality. Although vehicle emissions continue to be the main sources of urban-generated air pollution, outdoing oil refineries, semi-trucks and aircraft as major polluters, vehicle exhaust emissions have been reduced tremendously thanks to catalytic converter use. By significantly reducing vehicle emissions, and by making vehicle exhaust more eco-friendly, catalytic converters continue to promote a healthier environment.

Drawbacks

For all their benefits toward reducing vehicle emissions, catalytic converters have two major drawbacks: they reduce engine horsepower and vehicle gas mileage slightly. A catalytic converter adds a small source of exhaust flow impedence, which causes a bit of engine back pressure to develop as the speed of engine exhaust is slowed down by the constrictive effects of the converter. This back pressure makes the engine work a little harder and results in a small horsepower decrease and a slight reduction in gas mileage.