Catalytic Converter

What is a Catalytic Converter and How Does it Work?

As much as vehicles are helpful in daily life, they also cause harm to the environment, emitting toxic gases. Catalytic converters play a major role in reducing the amount of toxic gases cars emit, catalyzing a redox reaction.

Catalytic converters were invented back in 1975. Some stringent laws and regulations govern automakers to restrict the amount of pollution a car is allowed to produce as a way of reducing pollution.

Pollutants Cars Produce

A car is powered when fuel is mixed with air and then burnt. The process leads to emission of some toxic gases that pollute the environment. The by-products produced after combustion include: Carbon monoxide (CO), Carbon dioxide (CO2), Nitrogen gas (N2), Nitrogen Oxides (NO and NO2) and hydrocarbons or volatile organic compounds (VOCs).

Gas emission into the atmosphere impairs air quality, increases greenhouse effect and also affects the ozone layer, explaining why it is important to ensure they are kept at a minimum. A catalytic converter is able to reduce the gases before emission from the exhaust system of the car to the atmosphere.

Modern cars are equipped with a three-way catalytic converter. It is three-way because it can reduce emission of three different gases at the same time. The converter reduces three gases, namely: carbon monoxide, nitrogen oxides (NOx) and hydrocarbons.

How Does a Catalytic Converter Work?

The catalytic converter works by performing two reactions – a reduction reaction and an oxidation reaction. The converter is coated with the metal catalysts, Palladium, platinum and rhodium. New models of catalytic converters use gold as the catalyst since it is cheaper than the other metals and has a high oxidation rate.

In the first stage, the converter reduces the nitrogen oxides, removing the nitrogen atom. This means that a free oxygen atom or two are then released into the atmosphere. The nitrogen molecule sticks to the surface of the catalyst. This happens on the platinum or rhodium metal surfaces.

The next step is oxidation. The platinum and palladium catalysts are responsible for oxidation. In this reaction, an oxygen molecule is added to the unburnt carbon monoxide or hydrocarbons to combust them. When carbon monoxide is oxidised, it is turned to carbon dioxide, a less poisonous gas.

Up the system before the catalytic converter is an oxygen sensor that determines the amount of oxygen in the exhaust system. Depending on the level of oxygen present, the fuel injection system is controlled so that the ratio of fuel to oxygen in the engine is regulated to the ideal ratio that reduces production of the pollutant gases.

Catalytic converters come in two different makes: either honeycomb or ceramic bead converters. The honeycomb converters are the most common. Although converters are helpful at reducing pollution from vehicles, a lot still needs to be done to enhance their effectiveness.

For instance, the converter only works when it is heated, meaning immediately after you start your car it stops working. Auto manufacturers should further invest in technologies that can help reduce environment pollution due to exhaust fumes.