Lets talk about how emission from vehicles are controlled [The catalytic converters]

There was a time here in Nigeria when we could predict the period of the harmattan season (i.e. the time frame of the season) and when the dry season was. we could also not forget that the rainy season was also predicted and August break happened in the month of August.

What I am trying to say we all are guilty of whatever we have done to take away this prediction and now it even rains during harmattan season and we now have harsh weather when it is not supposed to be so.
Well, I am not here to bring up matters that have been discussed severally here on steemit but rather a solution to the vehicles that you probably have seen but do not know what it is.

Have you ever sat down to examine your vehicle exhaust?

If you have, what do you see? And if you haven’t well today is the day you get to see closely what your exhaust manifold looks like. The first time I saw the exhaust of a vehicle was when I was playing football alongside my friends and unfortunately for us, our ball found itself stuck under my dad’s car I found this big looking thing just before the end of the exhaust pipe.

As I pulled the ball out from under the car I was left with a question as I asked my dad what this was and he called it a silencer. In Nigeria, we are used to that name already especially in our private vehicles where we are like “hey, be careful and don’t hit my silencer against a stone or a pothole”. (people with good roads would not understand.)
Well, I am here to tell you that that thing you call a silencer actually has another name and its called a muffler.

Mufflers do a good job of reducing the engine noise. I would be talking about them later in this post as I am not here to talk about the mufflers but rather something that looks like them in shape but are not the same these things are called the catalytic converter.

That sounds like chemistry, right?

Have you ever heard what a catalytic converter is or what it does or how it works?

Just hang on and sit tight as you are about to learn a new thing here today.

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What are catalytic converters?

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The catalytic converters are small devices (not that small but smaller than the mufflers) used at the exhaust manifold of engines to make the emissions from the engine safer.

When the exhaust or flue gases of combustion are coming out of the cylinder there are a lot of gases that comes out with it such as carbon monoxide, nitrogen oxide which are ready to be released into the environment. These toxic gases are made less toxic and much safer for the environment by the catalytic converters.
This is basically what the catalytic converter does, although there have been concerns about how the catalytic converters send back pressure and prevent the easy flow of exhaust gases out of the car engine.

The catalytic converters make use of special elements such as Platinum, palladium, and rhodium to carry out their jobs efficiently. The catalytic converters have special ceramics which are made in honeycomb shapes which these gases pass through while the elements do their jobs.

Imagine you going at a high speed on a highway and the vehicle right in front of you has no catalytic converter and it is emitting so much from the exhaust and you can’t even see this vehicle but just the smoke. This could be disastrous for the players of such roads.

Now imagine what happens in a city like Lagos with so many cars on the highway and lots of traffic jam, many of us would probably be dead before we get to our homes from work or even before we get to work from carbon monoxide poisoning. Therefore, I would say catalytic converters make not only our roads but environment safer.

And they could also be the reason for your engine overheating or your engine slow speed especially when they are clogged but without them, lots could wrong without them in a vehicle.

Let us talk about their invention.

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The catalytic story

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I guess the 19th (1950) century was not that bad for the motor vehicle as this marked the beginning of good things in the automobile. The catalytic converter was made patent by Eugene Houdry, a French engineer who heard the cries about the report of smog in England from vehicles.

He, therefore, moved to England where he created a company he called oxy catalyst where he first invented a catalytic converter for smokestacks. After the successful invention of what he called the cats for the smokestacks, there was an improvement which was made and brought about the catalytic converters for forklifts that used a low lead type of gasoline.

They were a great thing to behold but the expensive price of the catalytic converters kept people away from them until the emission control regulations became strict on the people. People were forced to use them in their vehicles.
There have been several improvements on the catalytic converters since the 1970 modifications as catalytic converters for turbines are being worked upon by several engineers. So, I don’t want to hear people say engineers do not care about their environment. Of course, we do!

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The working principle or method of operation in a catalytic converter

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The catalytic converters are found before the muffler in the exhaust pipe or manifold of engines and they are quite straightforward with just an inlet and an outlet in them but what happens in between the inlet and outlet is basically simple chemistry which one might have probably come across but does not know the application.

From the name catalysts, they are simply substances or things that hasten or slow without being used up in the process are simply catalysts and these are the things located right in the middle of the inlet and outlet of the catalytic converter.
the catalysts are made up of ceramics which such that the air from the exhaust passes through the honeycombed shaped ceramic catalysts. Actually, they have two and the two of them perform different functions in the catalytic converter.

The combustion of fuel, there are several products that come out in the combustion of fuel some of which are nitrogen oxide, Sulphur dioxide, carbon monoxide, carbon dioxide, lead, and matter.
The first ceramic substrate in the catalytic converter does what is known as reduction in chemistry. The reduction process takes place inside the first catalytic converter rhodium substrate by breaking or reducing the oxides of nitrogen (i.e. nitrogen oxide NO₂) into nitrogen and oxygen.

This reduction only does so in the rhodium substrate and it is only concerned with oxides of nitrogen in the flue gases of the engine. After separation, the remaining of the components of combustion alongside the unburnt fuel are left to pass through the other catalyst in the converter.

NO_2(g) = N_(g) + O_2(g)

The second catalyst in the converter is also like the first (I mean it has a honeycomb shape with holes which allows the gases that have been reduced and the other products of combustion to pass through it.) The ceramic substrate consists of two elements which are platinum and palladium. what this other substrate does is that it oxidizes the products of hydrocarbon and mixes the incomplete combustion with the extra oxygen gotten from it so that the carbon monoxide (CO) can react with more oxygen to form carbon dioxide(CO₂). This way the carbon released into the atmosphere is safer although not totally free from emission pollution but a product of nitrogen, oxygen, H₂O, and CO2 are much better than the initial gases coming into the converter.

This, basically reduces the hydrocarbon that is meant to be released into the atmosphere and replaces it with gases that could be used up by plants or mixes with the air although the catalytic converter is not 100% efficient but cars and vehicles in recent times are not advised to work on roads without them.

There are some catalytic converters which have extra nozzle for additional supply of oxygen into the catalytic converters. This nozzle supplies air into the catalytic converters just before it goes through the second substrate this is just to increase the efficiency of the converters.

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Clogging of the catalytic converter

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If you remember I said something about the catalytic converter causing back pressure to the engine thereby reducing the work the engine does or causes overheating to the engine.

The above conditions occur due to blocks in the honeycomb in the catalytic converter and this block would prevent the exhaust gases from escaping thereby causing something called back pressure and with high pressure still in your engine, there is definitely going to be high temperature thereby causing your engine not to attain full speed or overheating of the engine.

Some people do not like catalytic converters because they are too expensive and they reduce the rate at which the exhaust releases the gases. The catalytic converters are definitely expensive due to the elements in their substrate as rhodium, palladium, and platinum are not readily available and cannot be found everywhere. And of course, I believe there is no way a honeycomb can do a great job as open space when it comes to allowing air at high pressure to pass through. But its limited and I do believe it prevents free air movements out of the exhaust.

These are one of the things you might want to consider while using a catalytic converter.

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Conclusion

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In the exhaust manifold of the car engine, the catalytic converters come just before the mufflers although they may be similar to a small kid but are smaller and different in the eyes of an engineer and in some case the layman may mistake it for an extension for the car engine.

The catalytic converter just like the mufflers but have different functions. They are responsible for emission control in the vehicle engines. They make life worth living and prevent us from killing ourselves in a city. Just as the French engineer came to the rescue in England when reports started flying about smog in the city from vehicles. He was quick to move to England where he invented the catalytic converters which are further developed by other engineers.

The catalytic converter is a straightforward device with a single inlet and outlet and in between, there is a catalyst substrate which reduces and oxidizes products of combustion which are being produced from the engine cylinder.
This process reduces the hydrocarbon emissions and keeps the environment safe. So when next you are driving appreciate your catalytic converter as they made the car technology possible, without them we probably would still be riding horses and the rich would be spilling hydrocarbons in our noses.

Thank you for reading.

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References

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knowledge is not just gotten by sleeping it is gotten from books or by listening. Here are some of the books and links I read

• catalyticconverters history
• history-evolution-catalytic-converters
• wikipedia Catalytic_converte
• your-car-exhaust-system-explained
• catalytic converters
• drivingtesttips catalytic-converter
• Automobile Catalytic Converters textbook by Kathleen C. Taylor

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