The three-way catalytic converter is the most important external purification device installed in the automotive exhaust system. It can convert harmful gases such as CO, HC, and NOx in car exhaust into harmless carbon dioxide, water, and nitrogen through oxidation-reduction. This catalyst is called ternary because it can simultaneously convert the three main harmful substances in exhaust gas into harmless substances.

The working principle of a three-way catalytic converter is that when high-temperature car exhaust passes through the purification device, the purifying agent in the three-way catalytic converter will enhance the activity of CO, HC, and NOx, promoting them to undergo certain redox chemical reactions. CO is oxidized into a five colored, non-toxic carbon dioxide gas at high temperature; HC compounds are oxidized into water (H2O) and carbon dioxide at high temperatures; NOx is reduced to nitrogen and oxygen. Three harmful gases can be transformed into harmless gases, which can purify car exhaust.

A ternary catalytic reactor is similar to a muffler. Its exterior is made of double-layer stainless steel plates. Asbestos fiber felt is an insulation material installed in the interlayer of double-layer panels. The purification agent is set in the middle of the inner mesh partition. The purification agent consists of a carrier and a catalyst. Usually, the carrier is made of aluminum oxide, with shapes such as spherical, polygonal, and mesh separators. Purifiers actually act as catalysts, also known as catalysts. The catalysts are platinum, rhodium, and palladium. One of them forms a purifying agent when sprayed onto the carrier.

Generally speaking, a three-way catalytic converter does not require cleaning. If the three-way catalytic oxidation is severe, it can be replaced directly. Because the working temperature of the three-way catalytic converter is around 350, it is best to have no liquid water residue, so cleaning is not good.