What is a Three-Way Catalytic Converter in a Car?

[SanEliza]

A three-way catalytic converter is the most important external purification device installed in a car's exhaust system. The function of the three-way catalytic converter: It converts harmful gases such as CO, HC, and NOx emitted from car exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. Since this converter can simultaneously transform the main harmful substances in the exhaust into harmless substances, it is installed in the engine's exhaust pipe. Through redox reactions, it converts carbon dioxide and nitrogen, hence it is also called a three-way (efficiency) catalytic converter. How the three-way catalytic converter works: When high-temperature car exhaust passes through the purification device, the purifying agent in the three-way catalytic converter enhances the activity of the three gases—CO, HC, and NOx—promoting certain redox chemical reactions. Among these, CO is oxidized at high temperatures into colorless, non-toxic carbon dioxide gas; HC compounds are oxidized into water (H2O) and carbon dioxide; and NOx is reduced into nitrogen and oxygen.