Catalytic Converters Car

What is a Catalytic Converter?

A catalytic converter is an exhaust emission control device. Its purpose is to convert gaseous pollutants resulting from the internal combustion process of the engine into les harmful elements in order to protect the environment and public health.

It is increasingly common for a vehicle to have more than one catalytic converter in order to comply with regulations. Some catalytic converters are directly attached to the exhaust manifold; others may be fitted with a muffler and the exhaust pipe. Whether because it plays a key role in keeping vehicle emissions below regulatory limits, or because of the increasing incidences of theft, catalytic converters are the most talked-about vehicle parts today.

How do catalytic converters work and why are they used to reduce emissions?

By definition, a catalytic converter is an element that takes part in a chemical reaction by increasing its speed, but without directly intervening, in such way that its mass remains unchanged. This can be compared to a group of spectators cheering on cyclists in a race and giving them a boost with their encouragement alone.
The main polluting exhaust gases resulting from combustion are carbon monoxide (CO), incompletely burned hydrocarbons (HC) and nitrogen oxides (NOx).
Their presence in the air are linked to health problems in humans (increased chances of cancer and respiratory failure), as well as to the degradation of the atmosphere and biodiversity. As they pass through the channels of the catalytic converter ceramic substrates, the precious metals activate different chemical reactions (oxidation and reduction), which recombine the gas particles so that they exit the exhaust pipe in a converted form. In short:

• Carbon monoxide (CO) combines with oxygen (O2) to form CO2. This is an oxidation process.
• Hydrocarbons (HC) combine with oxygen (O2) to form a mixture of CO2 and water vapour (H2O). This is an oxidation process.
• Nitrogen oxides (NOx) combine with carbon monoxide (CO) to form a mixture of CO2 and nitrogen. This is a reduction process.

It is important to note that for these reactions to take place, the catalytic converter requires an operating temperature of over 450 degrees Celsius. At the same time, the reactions themselves release more residual heat, and therefore a good clue to diagnose whether a catalytic converter is working correctly or not is to measure the temperature at the inlet and at the outlet. If the temperature is higher at the outlet, the catalytic converter is certainly working properly.

Are catalytic converters for diesel and petrol vehicles the same?

Broadly speaking, yes. Emissions from both diesel catalytic converters and petrol catalytic converters are similar and need to be treated in order to comply with current regulations. However, the greater presence of oxygen due to the compression work of diesel engines means that nitrogen oxides cannot be reduced sufficiently. Therefore, since they only act on CO and HC through the oxidation process, catalytic converters for diesel vehicles are said to be “two-way” catalysts, while those for petrol vehicles would be “three-way” catalysts. To prevent nitrogen oxides from escaping freely through the exhaust, these are treated through the exhaust gas recirculation circuit, and in more modern vehicles, through selective reduction catalytic converters. The latter is a special device, which needs a urea-based reducing agent so that the reduction processes can be activated and completed.

At Kat Europe we have a wide range of vehicle catalytic converters to cover the needs of over 90% of the European car fleet, offering the best prices in the market and fast and efficient shipping. If you have any questions concerning catalytic converter performance or how to find the right catalytic converter for your vehicle, please do not hesitate to contact us or to visit our help centre.