Catalytic Converters: Reducing Pollution, Saving The Planet

Cars, buses, and trucks have been a great gift to the world, but their engine pollution spoils the places where we live and harms our health. Fortunately, most vehicles are now fitted with pollution-reducing units called catalytic converters. These converters are a type of exhaust emission control device that uses a catalyst to convert harmful compounds in car exhaust into less harmful emissions. They are designed to reduce immediate, local air pollution and turn harmful chemicals in vehicle exhausts into harmless gases such as steam.

Catalytic converters reduce nitrogen oxide emissions

Nitrogen oxides (NOx) are a major contributor to air pollution, causing smog and acid rain, which are harmful to human health and the environment. Catalytic converters are designed to reduce these harmful emissions from car engines.

A catalytic converter is an emissions control device that uses catalysts to convert harmful pollutants into less harmful emissions before they leave a car's exhaust system. It is a simple yet effective device, converting around 98% of harmful fumes produced by a car engine into less harmful gases.

The reduction of nitrogen oxide emissions is one of the three regulated emissions that three-way catalytic converters help to reduce. The other two are the oxidation of carbon monoxide and the oxidation of hydrocarbons.

The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce NOx emissions. When an NO or NO2 molecule comes into contact with the catalyst, the catalyst removes the nitrogen atom from the molecule and holds onto it, releasing the oxygen in the form of O2. The nitrogen atoms then bond with other nitrogen atoms stuck to the catalyst, forming N2.

The use of catalytic converters has led to a significant decrease in nitrogen oxide emissions from vehicles. They are now commonly used in most modern cars, as well as other vehicles such as generators, buses, trucks, and trains.

However, it is important to note that catalytic converters only work effectively at high temperatures, usually above 400 °C (750 °F). Therefore, they are placed close to the engine to ensure they reach the required temperature.

They reduce carbon monoxide emissions

Catalytic converters reduce carbon monoxide emissions by converting carbon monoxide into carbon dioxide. This is done through oxidation, a chemical process that adds oxygen to the carbon monoxide.

Carbon monoxide is a harmful and poisonous gas that is produced when there is not enough oxygen available to completely oxidise the carbon fuel in internal combustion engines. Catalytic converters provide a site for this oxidation to take place, converting carbon monoxide into carbon dioxide, which is less harmful.

The oxidation catalyst is the second stage of the catalytic converter. It uses a platinum and palladium catalyst to aid the reaction of carbon monoxide with the remaining oxygen in the exhaust gas, converting it into carbon dioxide.

The catalytic converter also reduces other harmful emissions, such as nitrogen oxides and hydrocarbons, through a combination of oxidation and reduction reactions.

They reduce hydrocarbon emissions

Hydrocarbons, or volatile organic compounds (VOCs), are a major component of smog, which is harmful to human health and the environment. They are produced mostly from evaporated, unburned fuel. Catalytic converters reduce hydrocarbon emissions by converting them into less harmful gases, such as carbon dioxide and water vapour.

The oxidation catalyst in a catalytic converter is responsible for reducing unburned hydrocarbons. This catalyst uses an oxidation reaction, which adds oxygen, to turn hydrocarbons into carbon dioxide and water. For example, the chemical reaction for the oxidation of hydrocarbons can be represented as:

CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O

This reaction occurs when the gases from the engine fumes blow over the catalyst, causing chemical reactions to take place on its surface. The catalyst is typically made from platinum or similar metals, such as palladium or rhodium.

The honeycomb structure inside the catalytic converter means that the gases touch a larger area of the catalyst at once, increasing the efficiency of the conversion. The honeycomb structure is made from a ceramic material and coated with the catalysts.

The oxidation of hydrocarbons is one of three different chemical reactions that occur simultaneously in three-way catalytic converters. The other two reactions are the oxidation of carbon monoxide into carbon dioxide and the reduction of nitrogen oxides into nitrogen and oxygen gases.

In summary, catalytic converters reduce hydrocarbon emissions by using an oxidation catalyst to convert hydrocarbons into less harmful gases, such as carbon dioxide and water vapour. This process is essential for reducing smog and improving air quality.

They require the use of unleaded fuel

Catalytic converters are emissions control devices that use catalysts to convert harmful pollutants into less harmful emissions before they leave a vehicle's exhaust system. They are fitted to most modern vehicles and turn harmful chemicals in vehicle exhausts into harmless gases such as steam.

Catalytic converters require the use of unleaded fuel because the lead in conventional fuel "poisons" the catalyst, rendering it unable to absorb the pollutants in exhaust gases. Lead leaves a residue that coats the catalytic metals (platinum, rhodium, and palladium) and prevents contact with the exhaust fumes, which is necessary for the redox reactions that reduce harmful emissions.

Lead in fuel can also cause cardiovascular problems in adults and adverse reproductive issues in women, such as disturbing the menstrual cycle and reducing fertility. Therefore, the use of unleaded petrol is recommended for vehicles with catalytic converters.

It is worth noting that catalytic converters are sensitive devices, and their functionality can be inhibited by several substances and chemicals, including lead, manganese, and silicon. Lead has a particularly detrimental effect, as it requires running the engine at high temperatures to reverse the damage, and even then, if the lead poisoning is severe enough, the converter may need to be replaced.

They are targeted by thieves

Why catalytic converters are targeted by thieves

Catalytic converters are targeted by thieves because they contain precious metals such as platinum, rhodium, and palladium, which are worth more than gold. A standard catalytic converter contains several hundred dollars' worth of these metals. Thieves can easily sell a stolen catalytic converter for $200 or more, with scrap values ranging from £500-£1000.

The rise in catalytic converter theft is driven by the value of the metals inside. While platinum prices have remained fairly stable, there has been a sharp increase in the value of palladium. When precious metal prices go up, the demand for parts that contain them also increases, and the risk of catalytic converter theft rises.

Additionally, stealing a catalytic converter is a relatively simple task. All a thief needs is a reciprocating saw or an angle grinder, and they can cut out the unit from under a car in less than 60 seconds to a few minutes. SUVs and trucks are common targets because their higher ground clearance makes it easier to access the catalytic converter. These vehicles also tend to have larger engines, so their catalytic converters contain more precious metals.

To prevent catalytic converter theft, car owners can take measures such as parking in secure locations, installing security cameras or alarms, using anti-theft devices, and etching or watermarking their catalytic converters for easier identification if stolen.

Frequently asked questions