Three-way catalysis refers to the catalytic action of converting harmful gases such as CO, HC and nitrogen oxides in automobile exhaust into harmless carbon dioxide, water and nitrogen through oxidation and reduction. Three-way catalytic converter is mainly used. The carrier part of the three-way catalytic converter is porous ceramic material, which is installed in a special exhaust pipe. It is called a carrier because it does not participate in the catalytic reaction itself, but is covered by a layer of precious metals and rare earths such as platinum, rhodium and palladium. It is the most important external purification device installed in the automobile exhaust system.
The working principle of the three-way catalytic converter is as follows: when the high-temperature automobile exhaust gas passes through the purification device, the purifying agent in the three-way catalytic converter will enhance the activity of carbon monoxide, hydrocarbons and nitrogen oxides, and urge them to carry out certain redox chemical reactions, in which carbon monoxide is oxidized into colorless and nontoxic carbon dioxide gas at high temperature; Hydrocarbons are oxidized to water (H2O) and carbon dioxide at high temperature; Nitrogen oxides are reduced to nitrogen and oxygen. Three kinds of harmful gases are changed into harmless gases, thus purifying automobile exhaust. As long as oxygen is still available and the air-fuel ratio is reasonable.