Why Do We Need Catalytic Converters?

Catalytic converters have become commonplace in today’s world of motor vehicle usage. It has not always been this way. In the past, rising pollution levels due to vehicle exhaust fumes have become the cause of the haze of smog that fills the air over many major cities. With millions of cars on the roads across America, it is no wonder something had to be done.   

To solve this problem, cities, states, and the federal government created clean-air laws that restrict the amount of pollution that cars can produce. Over the years, automakers have made adjustments to fuel systems and car engines to keep up with these laws. 

The largest leap in technology to date to combat car emission pollution has been the introduction of the catalytic converter.

Where Did The Technology Come From?

It started in 1950 by a man named Eugene Houdry, a French mechanical engineer, who invented the first catalytic converter to reduce the amount of pollutants produced by motor vehicles. It was not until 1975 that the usage of these devices started to become widely used amongst the masses. In 1981, the installation of catalytic converters became mandatory in all vehicles manufactured. Today, it’s just another normal part of your car’s exhaust system.

What Pollutants are Catalytic Converters designed to reduce?

When driving a gasoline-powered vehicle, many substances are ejected into the world. Some are more harmful than others. 

On the lighter side, some are reasonably safe, such as nitrogen (N2) which is naturally in the air we breathe along with water (H2O) which you can see sometimes dripping from the exhaust pipe of your car. 

On the more harmful side, carbon dioxide (CO2), nitrogen oxide (NOx), and sulfur oxides (SOx) are major causes of air pollution and respiratory problems for many of our population. These emissions have been known to cause health problems like cardiovascular disease and cancer. Health problems like these can be caused by unburnt hydrocarbons (carbon particles), and volatile organic compounds (VOCs)

Vehicle engines also release carbon monoxide (CO) which is a poisonous gas that can replace oxygen in your bloodstream. If exposed to enough of this, it can cause permanent major respiratory problems and even death. Not to mention the damage it does to the upper layers of our atmosphere like the ozone layer.

How Do Catalytic Converters Reduce Pollutants?

As we all know, inside your engine 3 things need to happen in order to propel your car forward. You need a mixture of fuel, air, and a spark to create a small explosion. This moves one piston at a time, through one combustion at a time to keep your engine spinning and your car moving. That combustion releases some harmful chemicals which are moved out of your car’s engine through your exhaust system. 

Attached to your car’s exhaust pipe is your catalytic converter. A ceramic honeycomb is encased in a metal casing. The honeycomb is coated with noble metals. Noble metals are metals that are resistant to oxidation, corrosion, and acids. This means that they are able to stand up to moisture and all the chemicals released by your car’s engine.

Commonly the honeycomb is coated with platinum (Pt), palladium (Pd), and rhodium (Rh). These act as catalysts, which are compounds that trigger a chemical reaction without being affected or altered themselves resulting in a long lifespan of usage. These reactions convert the harmful chemicals into less harmful emissions, hence the name “Catalytic converter”.

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The reason for using a honeycomb design is to maximize surface area thus increasing the effectiveness of the system where the reactions take place.

As the engine runs, air is moved out of your car’s engine through the exhaust system pipes into the catalytic converter’s intake. From there, the gases from the engine fumes blow over the catalyst, chemical reactions take place on its surface, breaking apart the pollutant gases and converting them into other gases that are safe enough to blow harmlessly out of the tailpipe.

What Processes Take Place Inside Of The Catalytic Converter?

Catalytic converters use 2 reactions to reduce undesirable emissions. These are called reduction and oxidation.

1. Reduction is the process of removing oxygen.

A reduction catalyst made of platinum and rhodium is used to reduce nitrogen oxides (NOx) by removing nitrogen atoms from nitrogen oxide molecules (NO & NO2).

This unbinds the oxygen from the oxygen gas (O2) and from there nitrogen atoms attached to the catalyst react with each other. This creates nitrogen gas (N2) which can be harmlessly released out of your exhaust system.

2. Oxidation is the process of adding oxygen.

A reduction catalyst made from platinum or palladium reduces hydrocarbons (HC) and carbon monoxide (CO) by combining the carbon monoxide with oxygen to form carbon dioxide (CO2). Secondly, the unburnt hydrocarbons and oxygen combine to form carbon dioxide and water.Today’s catalytic converters use oxygen sensors to control how much extra oxygen gets pumped into the exhaust stream. The computer reads the data from the sensor and makes sure to feed the correct amount of oxygen into the system to maintain optimum efficiency for these oxidation and reduction reactions to take place, thus making for an extremely efficient pollution control system.

In short, catalytic converters take the dirty air from your engine, break the molecules into atoms, then recombine those atoms into safer substances such as carbon dioxide and are released back into the air. 

This is why we need a catalytic converter in all motor vehicles, and should make sure they are working in perfect order.

When you need to have yours checked, or replaced, always feel free to contact us and make an appointment.