A filter efficiency of 30 to 70 percent of the soot particles is sufficient for certain diesel engine applications. This is the case in, for instance, retro-fitted applications for the retrospective improvement of particle emissions. Particle catalysts perform well here in various configurations.
Heraeus offers various types of particle catalyst substrates. These range from knitted wire substrates to structured metal honeycombs and sintered metal structures. It is a characteristic of all these variants that they are partial flow filters. These have the advantage that under maximum soot loading they produce a finite increase in counter-pressure and thus do not damage the engine by inadmissibly high counter-pressures. Alternatively one can also describe these particle catalysts as "open filters". They enable a reduction of up to 70% of the particle mass both in the coated and in the uncoated variety. Relatively small and simple filter systems can often be implemented in combination with NO2 based regeneration.
Basically both passive and active regeneration measures can be applied, please find details under soot filters.