Metallic catalysts, cerium and iron, are used as fuel additives. These accelerate burn-off of the diesel particulates and lower the temperature at which burn-off can occur.
Each time after the fuel tank is filled, a metered quantity of fuel additive is injected into the fuel tank where it mixes with the fuel. When combustion takes place, the cerium and iron traces mix with the particulates from the diesel exhaust gas and provide for a considerably lower burn-off temperature. As a result, the particulate matter collected in the filter can be burned off at temperatures of just over 450 ยฐC.
The homogeneously bound cerium oxide/diesel particulate matter is then filtered out by the particulate filter, where it becomes embedded. Due to the combination of fuel additives (reduction in the burn-off temperature of the particles) and the engine management system (increase in the exhaust gas temperature) diesel particulate filters can be regenerated not only under full load conditions, but also in the partial load range at comparatively low exhaust gas temperatures typical for urban traffic.