What’s Inside a Catalytic Converter?
Catalytic converters are an important part of a vehicle’s exhaust system. The function of a catalytic converter is to convert toxic exhaust fumes and gases into less toxic ones.
In other words, catalytic converters reduce the emissions of hydrocarbons in the exhaust gases produced by internal combustion engines. This is a highly innovative process that requires changing the chemical composition of these gases before they are expelled from the vehicle.
Have you ever wondered what’s inside a catalytic converter that makes this process successful? Imagine a metal chamber with a few passageways inside.
Many people liken catalytic converters to a beehive because they have so many tiny passageways. But this special honeycomb is made of a ceramic-based composite and many precious metals.
When exhaust gases enter the honeycomb of a catalytic converter, they pass through several different passageways. This causes a chemical reaction to occur that removes toxic pollutants.
Each of these passages is coated with a metal catalyst, such as palladium, platinum or rhodium. These metals contribute to chemical reactions that reduce hydrocarbons, NOx gases and carbon monoxide in the exhaust gas.
It is important that the surface area of the catalyst material is as large as possible. For this reason, catalysts have a honeycomb structure. These precious metals themselves are very expensive. Many car thieves will try to steal catalytic converters from cars just to get their hands on these expensive metals.
Types of Catalysts
Let’s look at the two main types of catalytic converters used in gasoline vehicles and the metals they are made of.
Oxidation Catalysts
Oxidation catalysts are composed of platinum metal and palladium metal. When carbon monoxide and unburned fuel flow through the oxidation catalyst, these elements are converted into water and carbon dioxide.
Reduction Catalysts
Reduction catalysts are composed of rhodium metal and palladium metal. When nitrogen oxides from exhaust gases hit a reduction catalyst, these elements are converted into oxygen and nitrogen. This is very important to reduce smog, as nitrogen oxides are one of the main components of smog.
Previously, catalysts only performed two-way oxidation. This meant that there were only oxidation catalysts and no reduction catalysts.
However, the governments of Canada and the United States became concerned about the inability of the oxidation catalysts to convert nitrogen oxides into oxygen and nitrogen. This has led to changes in catalyst regulations, and now requires three-way oxidation-reduction.
Diesel oxidation catalyst
Diesel cars have their own catalyst, the so-called diesel oxidation catalyst. This catalyst absorbs hydrocarbons and carbon monoxide and converts them into carbon dioxide and water.
The catalytic converter uses oxygen in the exhaust stream to achieve this. Diesel oxidation catalysts are 90% efficient. Most visible particles and exhaust odors are reduced or eliminated.
Conclusion
Catalysts used to contain cheap metals such as nickel, iron, cerium, and manganese. However, these could not completely convert toxic exhaust gases into less harmful ones.
Changes in regulations regarding carbon emission standards forced automakers to use more expensive metals in catalytic converters. In fact, platinum, rhodium, and palladium are the best metals to reduce hydrocarbons and nitrogen oxides.
If you need to replace your catalytic converter, it will probably cost you between $1,000 and $3,000. Again, you pay for the precious metal and its value. Don’t choose the cheap way and avoid replacing your catalytic converter, or you may face legal issues in your country if you are arrested.