What catalytic converter is!

What is a catalytic converter?

A catalytic converter converts the harmful exhaust gases produced by the engine into less harmful emissions before they leave the vehicle's exhaust system.

The catalytic converter looks similar to a muffler. It is typically a stainless steel housing with a ceramic honeycomb inside that is impregnated with platinum, palladium, and rhodium. These elements help clean up harmful exhaust gases that otherwise would be expelled from the tail pipe.

It is common for a four-cylinder engine to be equipped with one or two catalytic converters, while six and eight-cylinder engines can have up to four.  

How does the catalytic converter work?

The catalytic converter has multiple sections, commonly referred to as beds. Each contains specific catalyst elements that work at a temperature of at least 400 degrees F to promote specific chemical reactions. This converts harmful CO, HC, and NOx exhaust gases into less harmful CO2, H2O, and N gases that are released from the vehicle's exhaust pipe.

The first section of the catalytic converter is called the reduction bed and is coated with rhodium. It is called the reduction bed because its purpose is to reduce the NOx gases back in to harmless nitrogen and oxygen.

The next section of the catalytic converter is the oxygen storage bed, which is coated with cerium. Its purpose is to maintain an ideal level of oxygen for use by the rear of the converter. It does this by storing and releasing the oxygen that gets released from the reduction of NOx in the previous reduction bed.

The oxygen is then available for use in the final oxidizing bed, which is coated with platinum and paladium. The purpose of the oxidizing bed is to complete the combustion of CO by adding oxygen. The oxidizing bed also uses oxygen to burn any of the raw HCs that still remain in the exhaust gases.