With the tremendous increase in population, the government has put guidelines to curb it. The pollutants include nitrogen oxides, hydrocarbons, and carbon monoxide, especially from vehicles.
There is National Emissions Standards Act that vehicle manufacturers have to meet to reduce environmental pollution from automobiles. A catalytic converter is one of those devices useful in controlling emissions.
It is fitted in your car’s exhaust system to reduce toxic gases emission and fumes from the engine. The catalytic converter converts the gases into environmentally friendly and less harmful gases.
Do diesel cars have catalytic converters? Yes, diesel cars have catalytic converters.
What is a Diesel Catalytic Converter?
A diesel catalytic converter is a crucial component for your vehicle.
A diesel catalytic converter helps control emissions. Thus, a catalytic converter helps reduce fumes and toxic gases from your car’s internal combustion.
In this regard, a diesel catalytic converter is a pollution filter for your car and a re-arranger.
The diesel catalytic converter rearranges atoms, transforming the chemical exhaust fumes components.
The process of filtering pollution in a diesel converter happens in four phases;
Diesel Oxidation Catalyst (DOC), Exhaust Gas Recirculation (EGR), Selective Catalytic Reduction (SCR), and Diesel Particulate Filter (PDF).
Do Diesel Engines Have Catalytic Converters?
Yes, diesel cars have a catalytic converter. However, the catalytic converter is different from gasoline or petrol cars.
However, most diesel engines have an emission control system with EGR, PDF, DOC, and SCR stages.
The DOC and SCR stages both use catalysts to facilitate chemical reductions to help in decreasing automobiles emissions.
Most of the diesel cars and engines use the two-way catalytic converter. This process has only a diesel oxidation catalyst that helps in converting carbon monoxide to CO2 and changing hydrocarbons to carbon dioxide and water.
At the same time, most modern cars are fitted with three-way catalytic converters. That means they have two-way diesel oxidation catalysts for oxidizing carbon monoxide.
In addition, they are equipped with selective catalytic reduction that helps in reducing nitric oxide and nitrogen dioxide emissions, both called NOx.
How Does a Diesel Catalytic Converter Work?
Diesel engines function differently from gasoline engines. Vehicles powered by gasoline have an internal combustion engine, and they use a spark for burning the fuel.
On the other hand, diesel engines use compression for igniting fuel. Diesel engines thus need a higher air-to-fuel ratio to have adequate oxygen for complete ignition.
The diesel catalytic converter works in four phases as follows;
1. Diesel Oxidation Catalyst (DOC)
The DOC is useful in converting carbon monoxide into carbon dioxide and breaks down unused fuel.
Every diesel system has a diesel oxidation catalyst. It works the same as it works in a gas catalytic converter.
Although the DOC is the smallest component of the diesel catalytic converter, it has the greatest recycling value as it contains palladium and platinum.
Mainly, the DOC is like the first component of the exhaust system.
2. Diesel Particulate Filter (PDF)
Diesel engines produce extra particulates or (soot) pollutants, unlike an internal combustion engine.
In this regard, the PDF captures the particulates by using a wall-flow monolith.
This wall-flow monolith is made up of alternating open and close channels to allow the particulates to enter the converter from the side of the inlet.
At the same time, it holds the particulates until they break down and are then removed via the regeneration process.
The regeneration process is equivalent to the oxidation process in the DOC, where the burning of organic materials occurs to produce carbon dioxide and water.
Therefore, to help the regeneration process, the PDF is loaded with tiny amounts of palladium and platinum to catalyze the reaction.
In addition, you need to heat the PDF to very high temperatures to allow the particulates to burn and pass via the filter walls than out the tailpipe.
Your car’s onboard computer then controls the regeneration process.
3. Selective Catalytic Reduction (SCR)
SCR is useful in the reduction of NOx gases. It is the largest diesel converter, yet it has little value in recycling.
Rhodium catalyzes the reduction reaction converting NOx to nitrogen and oxygen in a three-way converter. However, diesel exhaust has high oxygen, so Rhodium cannot reduce NOx efficiently.
So, diesel converters do not have Rhodium and instead use diesel exhaust fluid (DEF), an additive consisting of urea or ammonia. The ceramic monolith has catalytic materials, but they have no recycled value.
Therefore, the DEF and catalytic materials remove the NOx efficiently from the exhaust system.
Exhaust Gas recirculation (EGR) is another process of reducing NOx in a diesel system. However, the process does not need SCR or DEF. The SCR and PDF are downstream of the DOC, but you can still exchange their positions.
4. Recycling Diesel Catalytic Converters
Diesel engines come in many forms; they range from personal and commercial cars to heavy machines and industrial applications.
When buying a catalytic converter, it is good to note the different sizes, configurations, and precious metal contents.
Biscuit size can sometimes mislead you, and it might be challenging to identify the SCR, which is less valued, and DOC, which is highly valuable.
So if you are buying or selling scrap diesel converters, ensure you use the right tools for testing DPFs and DOCs to get the right price.
Frequently Asked Questions (FAQ)
Are diesel catalytic converters worth anything?
Diesel catalytic converters are not costly because they do not have precious metals like palladium, platinum, and Rhodium.
However, you might also get some diesel catalytic converters worth a lot of money.
Do diesel catalytic converters get stolen?
Diesel catalytic converters are stolen but are not much of a target like gasoline catalytic converters.
In the case of diesel vehicles, the catalyst for diesel oxidation is integrated with PDF, and there is proof that they are now stolen because of the value of their scrap value.
How much is a diesel catalytic converter worth in scrap?
Mostly, the value for diesel catalytic converter in scrap ranges below $5 to $10.
Do old diesel engines have catalytic converters?
Catalytic converters function with internal combustion engines driven by gasoline or diesel.
Therefore gasoline vehicles since 1992 have catalytic converters while diesel vehicles since 2001 are fitted with catalytic converters.
Final Thoughts on Diesel Catalytic Converters
In conclusion, a catalytic converter is an essential component for your car and the environment.
Do diesel engines have catalytic converters? Yes! Vehicles with engines powered by diesel have catalytic converters to control emissions.
However, diesel engines function differently from gasoline engines.
Lastly, while cars powered by gasoline have internal combustion engines and use spark for igniting fuel, diesel engines use compression for ignition. So, there is a need for a high air-to-fuel ratio to provide sufficient oxygen for complete combustion.
Go ahead if you want to get a vehicle with a diesel catalytic converter!
They are less costly and not a common target for thieves.
Hi I’m Marshall based in 1478 Doctors Drive Santa Monica, CA. I’m your DIY Car Repairman with more than 5 years experience in automobile repair, a skill I learned from my old man.
I started this blog to share my experience on both simple and technical aspects of your car.