Possibilities of Particle Reduction for Diesel Engines

Particulate emissions from diesel engines mainly consist of soot and high-boiling hydrocarbons (volatile fraction).

To reduce the volatile fraction different precious metals and their combinations are tested in traps and supports especially at low loads. A sufficient catalyst's efficiency at low exhaust-gas temperatures (low load) requires a large active catalyst surface. Due to the soot in the diesel exhaust-gas, the catalyst can be covered by a soot layer reducing the catalyst's efficiency.

The accumulated soot in the trap must be oxidized. Nonprecious metal catalysts are able to lower the soot ignition temperature. The reduction in ignition temperature depends on the catalyst material used. The influence of the catalyst's concentration and the use of an additional washcoat are also investigated.