Every car in the world has an internal combustion engine with a catalytic converter, or at least it should have. Otherwise, it would not just be hazardous for the environment, but that air would be, as well, dangerous for pedestrians and even the ones who drive the car. The main task of a catalytic converter is to turn harmful emissions from the exhaust system into something less toxic. In the end, all the poisonous gasses are sent back to the atmosphere in a less polluting form.
This technology is not something new and unheard of. Every vehicle has it, but there is no reason that you should not worry about its replacement. Well, at least most of the time, unless it breaks or, in the nowadays more common practice, someone tries to cut it out and steal it.
The first catalytic converters were invented and used in mass car manufacturing around the mid-70s. Shortly after, it became used in almost every vehicle with an internal combustion engine. These days they have many different shapes and sizes. Still, after all these years, manufacturers put them in the same place – between the car’s muffler and engine. The main reason is that they need high temperatures to do their job properly, and the best place for that is near the engine. In some vehicles, there is more than one converter. So, how do they work?
There are many types of catalytic converters. A simple two-way oxidation process, especially in older cars, turns CO (carbon monoxide) into CO2 (carbon dioxide). At the same time, other particles of the unused fuel converts into water and CO2. Meanwhile, in modern cars, way more advanced converters are being used. Those converters do all the actions that we mentioned before. Still, at the same time, they reduce NO2 (nitrogen dioxide) and NO (nitric oxide), which is more commonly known as the main reason for air pollution. Cars that use diesel engines have slightly different converters, mainly because they must cope with specific emissions that their ignition process produces. Those converters are often combined with varying exhaust systems, such as gas recirculation, diesel particulate filters, etc.
As we mentioned before, catalytic converters during the chemical reaction process change toxic substances, such as carbon monoxide, to less toxic ones, such as carbon dioxide. Inside it looks like a honeycomb surrounded by a substance that allows this process to start.
It is hard to argue that if not for catalytic converters, all main roads and most populated areas would be much smogier than they are now. And all that smog would be even more toxic to people and the environment. Because they are vital for reducing short-term pollution, they are always considered beneficial. Some say, as well as EV batteries that during their manufacturing process, there is more long-term harm to the environment than gain. However, as technology progresses, newer catalytic converters reduce even more carbon emissions, so in the future, all negative aspects of this process will outweigh the negative ones.
So, what makes it so expensive? The main reason is that precious metals, like platinum, palladium, rhodium etc., are used during their manufacturing process. Which can be easily recovered after the vehicle is scrapped. Thus, catalytic converter recycling is very important.
1) What is a catalytic converter and what is its purpose?
A catalytic converter is part of a vehicle’s exhaust system. Its main purpose is to transform harmful gases such as carbon monoxide (CO), unburned hydrocarbons (HC), and nitrogen oxides (NOx) into less toxic substances like carbon dioxide (CO₂), water (H₂O), and nitrogen (N₂). This reduces air pollution and helps vehicles comply with emission standards.
2) How does a catalytic converter work?
Inside the converter, there is a honeycomb structure coated with precious metals—platinum, palladium, and rhodium. When exhaust gases pass through at high temperatures, these metals trigger oxidation and reduction reactions:
The oxidation part converts CO and hydrocarbons into CO₂ and H₂O.
The reduction part (in three-way converters) reduces NOx to nitrogen (N₂).
Diesel engines use slightly different converters, often combined with systems like EGR (Exhaust Gas Recirculation), DPF (Diesel Particulate Filter), and SCR (Selective Catalytic Reduction) to handle diesel-specific emissions.
3) What are the signs that a catalytic converter may need replacement?
Common symptoms include reduced engine performance, increased fuel consumption, a sulfur or “rotten egg” smell, check engine light (MIL) warnings, metallic rattling noises from the exhaust, or failed emission test results. These usually indicate clogging, overheating, or internal damage.
4) Can you drive without a catalytic converter and what are the consequences?
While the car may still operate, driving without a catalytic converter is illegal in most countries. It dramatically increases pollution, triggers ECU errors, can damage other exhaust components, and causes your car to fail inspection. Additionally, the exhaust becomes louder and more harmful to both passengers and pedestrians.
5) Why are catalytic converters expensive and why is recycling them important?
Catalytic converters are costly because they contain precious metals like platinum, palladium, and rhodium. These metals can be recovered after the car is scrapped, making recycling both economically and environmentally important. Recycling reduces the need for new mining, conserves resources, and allows manufacturers to reuse valuable materials.