What Does a Catalytic Converter do?

If you live in a major city you may have seen streets and buildings turn blacker overtime. And maybe you are wondering what the cause is. Well, in the last few decades life has become easier since we can move from one place to another and transport anything easily using automobiles.

What Does a Catalytic Converter do

In every country today, there are thousands if not millions of trucks, buses and cars which all emit gases that pollute the air. This is the cause of blackened structures and is also harmful to human health.

Luckily, the automobile industry has come up with a gadget known as catalytic converter in their quest to reduce air pollution. So, what is a Catalytic Converter?

Catalytic Converter

It is a gadget that is fitted in automobiles to create an oxidation atmosphere which ensures fuel by products such as hydrocarbons, carbon monoxide etc. are turned into harmless matter like nitrogen and carbon dioxide gases.

The harmful fuel by-products are produced because of inadequate oxygen in the exhaust area to completely oxidize these gases to form water and carbon dioxide.

Molecules forming these pollutant gases are fairly safe. Therefore, if these molecules are broken up before they are released into the air, pollution would be reduced. This is what catalytic converters are made for.

These gadgets are simple but their impact is remarkable. This article will show you what catalytic converters do but first it will analyze fuel pollutants that come from incomplete combustion of fuel in car engines.

Car Engine Pollutants

Diesel and gasoline used to run car engines are petroleum products. Formation of petroleum takes place when minute ocean organisms decompose, gets heated up then percolate in rocks on the ocean bed.

It comprises of hydrocarbons since those minute ocean organisms are made up of hydrogen and carbon atoms.

Theoretically, combustion of all types of hydrocarbon fuels leads to production of huge amounts of energy and form water and carbon dioxide. These products of combustion are less harmful. However, practically speaking hydrocarbons are not the only elements found in gasoline.

It contains more than 140 different elements which come from additives.

This makes it not to possible to burn completely. The byproduct of this incomplete combustion are the air pollutants. That cloudy, dark vehicle smoke we are aware of is a result of nitrogen oxides, vaporous organic substances and carbon monoxide (a very dangerous gas to human health) produced by car engines.

Catalytic Converters Job

In simple terms, a catalyst is a substance that speeds up a synthetic process without been altered. A football coach is a good example. The coach only gives instructions on what is to be done but does not get in the field to play.

In the case of catalytic converter, its work is to make the process of removing pollution faster. Rhodium or palladium which have similar characteristics as platinum are used to make the catalyst.

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There are two pipes connecting the catalytic converter to the outside of the car and the converter itself is a huge box made of metal tucked into the car’s underside. Fuel is burned in the engine to produce energy.

When this happens, fumes produced from the combustion of fuel are transported to the convertor box through the first pipe.

Another pipe connects to the car’s exhaust and is responsible for removing the final products from the catalytic chamber.

Entering the catalytic converter, fumes from the engines meet the catalyst causing a reaction which splits the molecules of the poisonous gases and forms safe products ready to be transported out of the system.

Note that you need to use fuel which does not contain lead because lead contaminates the catalyst making it fail to execute its work. Over the years, automobile engineers have been working hard to make catalytic converters that can work perfectly at low heat which leads to better performance.

A catalytic converter’s inner part is made up of a structure that resembles a honeycomb. This structure is build using ceramic and the catalysts are bolted on it.

Efficiency and speed inside the converter are increased as the honeycomb structure increases the surface area of catalyst which the gases touch.

All catalytic converters comprise of two separate catalysts:

The first one is responsible for reduction process. In this process, oxygen is removed from nitrogen oxide (a pollutant) by splitting it up to form oxygen and nitrogen gases (safe gases as they exist naturally).

The second catalyst is responsible for the process of oxidation. In this process oxygen is added to carbon monoxide to produce carbon dioxide. Oxygen is also added to unburned hydrocarbon to form water and carbon dioxide

What Does a Catalytic Converter do

Overall, in the catalytic chamber, three unrelated processes take place concurrently. Catalytic converters in which these three processes take place are known as triple catalytic converters. However, some catalytic converters only accommodate the oxidation processes.

Such converters are less effective and are referred to as double catalytic converters. Steam (which is water in vapor form), carbon dioxide, oxygen and nitrogen gases are the products ejected out through the exhaust once the catalyst has finished its work.

Are Catalytic Converters Worthwhile?

The main function of catalytic converters is to ensure when you are on the wheel, your car does not pollute the local environment. Considering the work these small gadgets do, they are effective.

However, there is a long debate on whether catalytic converters are green. It is crucial to note that these converters do not completely get rid of these pollutants, they only reduce them.

A major drawback is these converters only work when temperatures are high. Therefore, when the engine has cooled, they do not work.

The first generations of catalytic converters could not work within the first few miles of driving because they required approximately fifteen minutes warming up.

If you drove for a short distance, they were totally unproductive. Today, these gadgets require about three minutes before they start to work and this means some pollutants are released into the air.

Second concern is increased climate change and global warming. While we know that carbon dioxide exists naturally in the air and think it is not harmful, it has led to increased global warming over the years.

To some, converters are behind increased carbon dioxide in the atmosphere because they oxidize carbon monoxide to carbon dioxide. Actually, even if this carbon monoxide was pumped into the air, it would change to carbon dioxide.

But, in the issue of global warming, environmentalists and car engineers state that during the reduction of nitrogen oxides to oxygen and nitrogen, nitrous oxide is made.

The potency of nitrous oxide is over 250 times that of carbon dioxide. And, because of the number of cars we have on the roads all over the world, nitrous oxide emitted is risky.

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Diesel engines and Catalytic Converters

Engines using gasoline and those using diesel do not work the same when it comes to catalytic converters. The difference in diesel engines is:

  • They use double catalysts meaning they only oxidize hydrocarbons and carbon monoxide.
  • They are designed to work at low temperatures.
  • Several catalytic converters are required in each vehicle because diesel is mostly used to run big vehicles.


There is always a chance for improvement and thankfully automobile engineers are working hard to come up with better catalytic converters. These small substances are a great addition to vehicles because they work excellently to minimize air pollution.

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