Particulate filters for petrol engines: Even cleaner thanks to filter

Mercedes-Benz is the first manufacturer to opt for the large-scale use of particulate filters for petrol engines to further improve their environmental compatibility. After more than two years of positive experience in the field with the S 500, in 2017 further S-Class variants will be equipped with the new M 256 and M 176 petrol engines with this technology. The filter will then be gradually introduced in other new vehicle models, facelifted models and new engine generations, such as the M 264. After that, use of the particulate filter is also planned for the current model series.

Back in 1985, Mercedes-Benz was the world's first automotive manufacturer to make diesel saloons in California optionally available with a particulate filter system. The company is now playing the same pioneering role for the spark-ignition engine, because the particulate filter for petrol engines reduces the emissions of fine soot particles. The filter works in a similar way to the technology in diesel vehicles: the exhaust gas stream is supplied to a particulate filter system, which, in the S-Class, is situated in the underfloor of the vehicle. The filter has a honeycomb structure with alternately sealed inlet and outlet channels. This forces the exhaust gas to flow through a porous filter wall, which traps the soot. The filter can be continuously regenerated under corresponding driving conditions.

Whereas Mercedes-Benz uses ceramic particulate filters of silicon carbide (SiC) in diesel vehicles, the particulate filter technology for petrol engines is based on cordierite, which is especially heat-resistant. Mercedes-Benz employs a particulate filter that is optimised for backpressure, has a high filtration efficiency and is also maintenance-free and self-regulating.