The number of cars on the road is increasing every day, and each one is contributing to air pollution, global warming, and toxicity in the environment. The only thing that’s responsible for limiting the damage and release of harmful gasses into the environment is the catalytic converter.
Almost every car you see on the road has a catalytic converter. In this blog, we will be discussing what a catalytic converter is, its functions and how it works.
History of Catalytic Converter
The catalytic converter is not a new concept. It was first introduced in 1975 to prevent harmful chemicals released into the air due to the combustion process. With time car emissions and global warming evolved into significant concerns for health organizations worldwide, which led to the discovery of European Emission Standards.
Read more: What Are Euro Emission Standards? Is Your Car Safe for the Environment?
In 1992, when the first euro standard was released, catalytic converters were made mandatory for auto manufacturers. With time there have been many upgrades to these emission standards.
What is a Catalytic Converter?
A catalytic converter is a simple device that converts harmful gasses like carbon monoxide, nitric oxide, hydrocarbons, and nitrogen oxides into less toxic CO2 and H20 vapors. The catalytic converter is connected to the car’s exhaust system.
As you drive the car, the exhaust gasses automatically pass through the catalytic converter, filtering the harmful toxins with the help of the honeycomb and ceramic beads structure.
What are the Pollutants Emitted From a Combustion Engine?
Ideally, a combustion engine shouldn’t emit any toxins, provided that the fuel is toxin-free. The mixture of air and fuel is so perfect that it’s entirely consumed in the combustion chamber. This is called a stoichiometric point. Gasoline engines have a stoichiometric point equal to 14.7:1. This means for every 1 pound of fuel burned, 14.7 pounds of air is burned. If the mixture is higher than the ideal ratio, it’s called lean combustion. Otherwise, if it’s lower, it’s known as rich combustion.
No combustion on earth is perfect, so it emits harmful gasses into the environment. Cars are programmed to keep the fuel and air mixture close to the stoichiometric point. However, it’s harder to keep the combustion ideal as you drive the car due to various road conditions.
As a result of incomplete emissions, the following are the most prominent emissions released into the air.
1. Oxides of Nitrogen
Air is 78% nitrogen, so it’s only natural that due to incomplete combustion, nitrogen oxides will be the most abundant toxins released from the exhaust. Common toxins include NO and NO2, often represented collectively as NOX.
2. Oxides of Carbon
Carbon present in the fuel is the primary reason behind COX (CO and CO2) produced during combustion. Carbon dioxide is a natural byproduct of combustion. However, carbon monoxide can also be produced in case of improper combustion. CO is toxic, depletes the ozone layer, and increases the global warming effect.
3. Hydrocarbons/ Volatile Organic Compounds (VOCs)
The imperfect combustion process leads to the production of Hydrocarbons of VOCs in the combustion chamber. These are the main components of fog and smog.
4. Water Vapors
Water Vapors are not a threat to the environment. But these are also results of the combustion process in the engine.
How does a Catalytic Converter Work?
A catalytic converter is based on a simple catalyst that converts COX, NOX, and VOCs into simple CO2 and H20. A catalytic converter is actually a box-shaped tool located under the car. This box-shaped structure has honeycomb meshes inside, having a catalyst applied to them. This catalyst is not a reactant or a part of the reaction. It speeds up the reaction and breaks down harmful compounds into simpler gasses.
Platinum or similar metals are used in catalytic converters due to their inherent effectiveness in converting carbon and hydrogen oxides to less harmful gasses. Combustion gasses are only refined if they get in touch with the catalyst. So to maximize the surface area, a mesh or a honeycomb grille is often used inside a catalytic converter.
Due to the use of expensive metals in the catalytic converter, these are expensive to replace.
There are two types of catalysts used in this process. A reduction catalyst and an oxidation catalyst. These are ceramic coated and applied to a metal catalyst like platinum, palladium, or rhodium. Without getting too technical, the reduction catalysts filter the NOX in the air while the oxidation catalyst cleans the VOCs and COX present in the exhaust gasses.
Air is not only cleaned in the catalytic converter, but it’s also used to signal the engine about the air-fuel mixture for better combustion. The oxygen sensor mounted on the catalytic converter senses the oxygen going into the air. Higher oxygen levels in the exhaust gasses indicate improper combustion. As a result, a car’s ECU alters the air-fuel ratio in order to minimize the quantity of unburned compounds in the exhaust gasses.
Common Problems with the Catalytic Converter and its Solution
You might have heard about the catalytic converter getting choked. Why does it happen, and what is the solution?
As explained earlier, a catalytic converter is based on a mesh/honeycomb structure to increase the surface area. This structure suffocates with toxic compounds sticking to the grille with time. Hence blocking the passage of exhaust gasses from flowing properly. This sends false signals to the oxygen sensors, altering the air-fuel mixture. As a result, fuel efficiency decreases.
A major culprit in choking the catalytic converters in Pakistan is bad fuel quality. The amount of carbon, lead, and nitrogen oxides present in the fuel, produces more toxins as it burns which slowly cause the catalytic converter to choke. Low-quality fuel chokes the catalytic converter, decreases fuel efficiency, and creates knocking issues.
So what’s the solution? A roadside mechanic might tell you to break the grille inside the converter. Don’t do it. Once you break the grille, nothing stops the harmful toxins from getting into the air without cleaning. Also, these grilles use expensive metals which can be reused. Not only that but your oxygen sensor might also get damaged or not pick correct readings at all. Hence destroying the fuel economy of your car.
The best solution is to replace the catalytic converter or get it cleaned professionally after periodic intervals.
Do you have any other solutions to offer? Let us know in the comments below.
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