Catalytic Converter

Catalytic Converter: Design, Types And Working Explained with Diagrams

What is a Catalytic Converter?

The catalytic converter or 'Cat-Con' is a mechanical device. It reduces the harmful emissions created in the exhaust system of an engine. It is an important device as it works with the harmful gases, which the engine creates during combustion of fuel. The main purpose of a catalytic converter is to reduce exhaust emissions.

Engine Exhaust System
Engine Exhaust System

The Cat-Con reduces the harmful exhaust gases through chemical reactions. It reacts with the harmful pollutants in the exhaust gases and turns them into lesser harmful gases. The catalytic converter consists of a special catalyst. It is made of platinum and palladium which carries out the chemical reactions.



Construction of Catalytic Converter:

The catalytic converter housing consists of a honeycomb core from inside. It is coated with precious metals such as platinum and rhodium. These metals react with the engine’s exhaust gases. They reduce the toxic contents of the gases and turn them into carbon dioxide and water.

Construction of catalytic converter
Construction of catalytic converter

At first, it reacts with the carbon monoxide generated by the combustion of gasoline. It also reacts with the hydrocarbons formed by unburned fuel and other nitrogen oxide emissions. Thus, the cat-con converts these gases into less harmful by-products which are the carbon-di-oxide, water vapor, and nitrous emissions.



Types of Catalytic Converters:

There are three different Types of Cat-Cons. The first type is the oxidation catalyst. It reduces harmful pollutants such as the carbon monoxide (CO) and fuel hydrocarbons (HC) in the exhaust. Simultaneously, it often uses a secondary air injection. However, the oxidation catalyst only reduces a portion of the pollutants.

Dual-bed:

The second type is the dual-bed catalytic-converter which offers more perfection. It works in two stages. There are two elements which are situated one behind the other. The first stage helps in reducing the amount of nitrogen oxide emissions. The second stage reacts with the hydrocarbons created by unburned fuel and carbon mono oxide. The manufacturers also provide the secondary air injection in the two-stage type cat-con.

Three-Way Catalytic Converter:

The last type is the Three Way Catalytic Converter. The Three-way catalyst helps in converting the harmful gases exhausted from the engine into harmless gases. The engine exhaust gases contain hazardous substances that cause damage to the environment. These include the oxides of nitrogen, hydrocarbons and carbon monoxide. The three-way catalyst converts them into less harmful carbon-di-oxide, water, and nitrogen.

Catalytic-Converter Honeycomb structure
Catalytic-Converter Honeycomb structure (Image courtesy: Eastern Catalytic)

The three-way cat-con is the only device which reduces all the three pollutants in one go. It functions most economically. Thus, most manufacturers employ a three-way type in their vehicles which need to meet stringent emission standards.

Working of the Three-Way Catalytic converter:

Furthermore, the three-way catalytic converter uses two catalysts; namely reduction catalyst and an oxidation catalyst. The oxidation catalyst is made of palladium and platinum whereas reduction catalyst is of rhodium and platinum. However, both of them come with a ceramic honeycomb structure. It is placed in a muffler like a compact unit which fits onto the exhaust pipe. Mainly, the automotive industry uses the Three-way Cat-con. This is because the vehicles have to pass many regulations for emission control.

Three-way Catalytic Converter
Three-way Catalytic Converter

Thus, the catalytic converter plays an important role in reducing the amount of pollution created. It also reduces the harmful emissions and gases created in the engine and the exhaust systems of all the cars across the globe.

Furthermore, for more information on cat-cons please click here:

Watch the Three-way Cat-Con in action here:

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