Diesel Particulate Filters & Catalytic Converters
on March 24, 2019

Thanks to the advances in technology, diesel engines have become popular all over the world over the past few decades. Diesel engines not only offer better mileage but also tend to be cheaper to run in the long run. One problem with diesel engines is they produce a lot of harmful chemicals that need to be cleaned before exhaust gases are let out. This is where the diesel particulate filter comes in.

How Diesel Particulate Filter Works

As the name suggests, Diesel Particulate filter is a filter that traps harmful diesel emission soot particles. Since this is a filter that traps particles, it needs to be cleaned on a regular basis to maintain the performance of the system.

Diesel particular filter cleaning is known as regeneration that can be active, passive as well as forced regeneration. In this process, the accumulated particles are burnt off at a high temperature which leaves behind a diesel particulate converterresidue of ash that effectively regenerates or renews the filter.

In the case of active regeneration, there are sensors that constantly read the soot load of the filter and activate adjustments to the fuel injection system that increases the exhaust temperature which in turn results in burning of the soot particles and clears the filter. This whole regeneration process takes around 10 min to complete. Depending on the type of a vehicle, this type of regeneration takes place every 400 to 600 km which varies on the use of vehicle.

In the case of passive regeneration, there is an integrated catalytic converter which is located close to the engine. It relies on the exhaust temperature being high enough to automatically burn off the soot particles.

In the case of forced regeneration, the vehicle starts displaying warning lights and goes into a limp mode. At this stage, one should take the vehicle to the dealer or a mechanic to fix the problem. In this process, a computer program is used for running the car. This program initiates DPF regeneration. The process also involves changing the engine oil and oil filter.

Catalytic Converter

Law was passed in 1975 in the US where government required every car to have a catalytic converter. The job of this device is to convert harmful pollutants in the exhaust gases into less harmful emissions before leaving the exhaust system of the car. These are extremely simple devices, but they have a great impact on the environment.

How Catalytic Converters Work

A car engine produces nitrogen gas, carbon dioxide, carbon monoxide, water vapour, nitrogen oxides and volatile organic compounds as emission. A catalytic converter has two types of catalysts namely a reduction catalyst as well as an oxidation catalyst. The inside of a converter is coated with a metal catalyst which is usually platinum, palladium and rhodium. Some of the newer converters also use gold mixed with other traditional metals.

The emissions containing nitrogen compounds and carbon compounds react with the catalyst lining the converter and it results in a chemical reaction that converts these harmful pollutants into less harmful pollutants. The catalytic converters also wear out with time which means that these need to be replaced to ensure that no harmful gases escape into the environment.

However, the old catalytic converter does not go to waste as there are some local companies actively engaged in catalytic converter recycling and profiting from extracting platinum and other precious metals lining the insides of the converters. These precious metals extracted from the converters can then be resold at the prevailing market price which means that one can get the good amount of cash for selling the old converter to one of the recycling companies.