The catalytic converter is an essential component in the exhaust system of a modern vehicle and is usually located under the car towards the engine. Its function is to decompose pollutants discharged from the exhaust pipe. According to new U.S. EPA emissions regulations, most gasoline-powered vehicles must equip with a catalytic converter. So what is a catalytic converter, and how does it work?
What is a catalytic converter?
The carrier part of the catalyst is a piece of porous ceramic material bolted to the car's underbody. The shell plays a protective role for the core, and the liner can fix the carrier and play the role of buffering and heat insulation. The catalytic converter is connected to two pipes. An input line connects to the engine and receives contaminated high-temperature fumes from the engine's cylinders. The other is the output pipe that connects to the exhaust system. When exhaust gas from the engine passes through the catalyst, it chemically reacts with the catalyst inside. Finally, the polluting gas is decomposed into other safe and harmless gases and discharged into the air. The catalytic converter is called a carrier because it does not participate in the catalytic reaction itself. Still, it relies on a layer of platinum, rhodium, palladium, and other precious metals covered on it to carry out the process. So how does a car catalytic converter work?
How does the catalytic converter work？
The working principle of the three-way catalytic converter is to convert harmful substances such as carbon monoxide, nitrogen monoxide, nitrogen dioxide, and hydrocarbons in automobile exhaust into less toxic substances such as carbon dioxide and water vapor through chemical reactions. 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 CO, HC, and NOx to promote their oxidation to a certain extent. Among them, CO will oxidize into colorless, non-toxic carbon dioxide gas at high temperatures. While HC compounds are oxidized to water (H20) and carbon dioxide at high temperatures, NOx is reduced to nitrogen and oxygen. The purified gas is harmless and will not cause environmental pollution.
There are usually two different types of catalysts at work in a catalytic converter. One is a reduction catalyst, and the other is an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst (usually platinum, rhodium, and palladium). This allows the maximum surface area of the catalyst to be exposed to the exhaust stream while reducing the amount of catalyst required. A second oxidation reaction also occurs inside the catalytic converter, converting any unburned hydrocarbons into carbon dioxide and water. Some of the latest converters are even using gold mixed with more traditional catalysts. That's all for how does a catalytic converter works.