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Catalytic Converter


The catalytic converter, also known as pollution control, is the muffler-like device used in the exhaust system which converts hydrocarbons and carbon monoxide to produce water vapor and carbon dioxide. The early catalytic converters contained a platinum-coated ceramic or aluminum oxide pellet coated with platinum, which requires more oxygen to properly perform because oxygen is pumped into the exhaust system by an air aspirator valve. The modern catalytic converters are constructed in a two-in-one design wherein the exhaust gases are sent directly to the substrate to allow chemical reaction.

  • The front section is called a three-way catalyst because it controls hydrocarbon, carbon monoxide, and nitric oxide by turning them into the water, carbon dioxide, and nitrogen.
  • The rear section is an oxidation catalyst that further reduces hydrocarbon and carbon monoxide.

 Vehicles with catalytic converters must use unleaded gasoline, Lead in gasoline coats the catalyst and makes it ineffective. For the catalytic converter to be most effective, the air-fuel mixture must have a stoichiometric ratio of 14.7:1. Small variations in the air- fuel ratio can cause large increases in exhaust emissions. Most automotive engines have an electronically controlled fuel system. It makes use of electronic fuel injection or a feedback carburetor to meter fuel. This is more accurately maintaining the desired air-fuel ration during operating conditions