Catalytic coated particulate filters

In addition to the reduction of CO, hydrocarbons and nitric oxides, the global reduction of particulate matter is one of the most urgent goals of environmental policy. Soot particulates are emitted especially during combustion processes in diesel engines as well as the combustion of heavy fuel oils as in marine applications.

A particulate filter removes particulate matter from the exhaust stream by physical filtration. The most efficient type is the so-called wall-flow filter. These substrates are similar to honeycomb structured substrates for common emission catalysts but blocked at alternative ends. Therefore, the exhaust gas is forced to pass the porous walls between the channels and the particulate matter is deposited on the walls. This type of filters is typically made of cordierite or silicon carbide. Since a continuous stream of soot would block the filter after a certain time, the filter has to be regenerated. Apart from regeneration (active/passive) durability, backpressure and catalyst activity are key issues. Hence, depending on the application and the conditions the substrates are coated in order to increase the efficiency of the exhaust gas system.

Below is an overview of our standard particulate filter coatings that we apply together with our customers, according to their specific requirements.

Regeneration

Once the pores of the filter are blocked the backpressure of the exhaust system increases and it has to be regenerated. This can be realised by a continuous process (passive regeneration) where NO2 from the exhaust stream is utilised in order to oxidise the soot. If the exhaust gas conditions are not suitable for a passively regenerating system, an active regeneration can be performed, in which the temperature is raised to around 600 °C in order to burn off the soot in the presence of oxygen.

Product characteristicCustomer benefitApplications
Filter for active regeneration (with oxygen)
• NO2-optimised
• high thermal stability
• fast soot regeneration
• PGM free possible
• low balance point temperature
• no additional NOx emissions
• long term durability
• cost effective coatings
Marine
Construction
Agricultural
Rail
Buses
Diesel Gensets
Light & Heavy Duty Vehicles
Filter for passive regeneration (with NO2)
• optimised balance point
• low pressure drop
• high PGM efficiency
• NOx abatement at lower temperatures
• Higher efficiency due to low pressure drop
Marine
Construction
Agricultural
Rail
Buses
Diesel Gensets
Light & Heavy Duty Vehicles