Core Technologies

F-DIESEL’ leading aftertreatment technologies are designed around proven core technologies. With a decade of experience with oxidation catalysts, particulate filters and SCR technology, our aftertreatment systems help optimize your entire engine system to operate more efficiently.

Diesel Oxidation Catalysts (DOC)

F-diesel diesel oxidation catalyst (DOC) technology can cut CO and HC emissions by more than 90%.

Our DOCs are designed to oxidise pollutants in light and heavy duty engines. Carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NO) are oxidised to carbon dioxide (CO2), water (H2O) and nitrogen dioxide (NO2).

CO + ½ O2 → CO2

[HC] + O2 → CO2 + H2O

NO + ½ O2 → NO2

Our diesel oxidation catalysts…

  • Are an ever-advancing technology that has been developed from our 30 years experience.
  • Allow vehicle and engine manufactures to meet strict emission legislation.
  • Can be optimised for bespoke systems and applications to meet customer requirements.
  • Oxidise NO to provide favourable NO:NO2 ratios for downstream catalyst reactions.
  • Can be further enhanced to contain zeolites for low temperature HC control.
  • Are highly durable against temperatures and poisons.
  • Utilise advanced materials for low light-off temperatures, enabling efficient use of precious metal.

Diesel Particulate Filters (DPF)

Diesel particulate filters are a proven and reliable emissions reduction technology with over 1 million F-DIESEL DPFs in use since 2004. DPFs are effective at removing over 90% of Particulate Matter (PM). Combination systems are designed for rugged off-highway markets and to fit tight space constraints. The use of passive and active regeneration also allows more control in oxidizing and cleaning the filter.

DPFs, combined with DOCs, use wall-flow substrates typically made of porous ceramic media that capture exhaust gas and remove PM or soot particles. A typical filter consists of an array of small channels for exhaust has to flow. Adjacent channels are plugged at opposite ends, forcing the exhaust gas to flow through the porous wall, capturing the soot particles on the surface and inside pores of the media. As soot accumulates in the filter, a regeneration event will provide sufficient heat to oxidize and capture the soot. The remaining ash can be removed during regularly scheduled cleaning events based on the recommendations of the engine manufacturer.

Selective Catalytic Reduction (SCR)

Selective catalytic reduction (SCR) systems work by chemically reducing NOx (NO and NO2) to nitrogen (N2). Johnson Matthey offers coated and extruded catalysts.

In a lean gas stream, it is necessary to add a reductant such as ammonia to the system to enable this reaction. Ammonia-SCR systems react ammonia (NH3) with the NOx to form nitrogen (N2) and water (H2O). There are three reaction pathways:

4NH3 + 4NO + O2 → 4N2 + 6H2O

2NH3 + NO + NO2 → 2N2 + 3H2O

8NH3 + 6NO2 → 7N2 + 12H2O

Any source of ammonia can be used, but most commonly the source is an aqueous solution of urea. This decomposes in the exhaust stream in two stages to form ammonia and carbon dioxide (CO2):


HNCO + H2O → CO2 + NH

Composition: Cu or Fe Zeolite or V-Titania coated on a flow-through monolith substrate.

Uniquely, we also offer extruded SCR catalysts which benefit from proven performance advantages as they have a catalytically active monolith.

Our selective catalytic reduction technology…

  • Benefits from market-leading Cu-Zeolite technology and a range of high-performance V-Titania systems.
  • Is developed for individual applications through our close work with the customer.
  • Helps enable our customers to meet increasingly stringent legislation.
  • Is highly durable against temperatures and poisons.
  • Has excellent functionality across a large temperature window.
  • Are being developed to help catalyst after-treatment systems achieve low N2O emissions, supporting future legislation requirements.

Nearly 1 million selective catalytic reduction (SCR) systems and complementary components have been in use worldwide since 2005. SCR systems are an effective and reliable technology that reduces oxides of nitrogen (NOx) emissions for a broad range of off-highway applications and enables enhanced fuel economy. Ideal for off-highway equipment, SCR systems are virtually maintenance-free with occasional dosing system filter maintenance depending on the application.

An SCR system is comprised of three main elements: SCR catalyst, urea dosing system and the aftertreatment control system. Our systems use a chemical reductant, in this case urea, which is called Diesel Exhaust Fluid (DEF) in North American or AdBlue in Europe. DEF or AdBlue converts to ammonia in the exhaust stream and reacts with NOx over a catalyst to form harmless nitrogen gas and water.

Ammonia Slip Catalyst (ASC)

F-diesel’s ASC technology removes residual ammonia (NH3) from upstream ammonia dosing systems, converting it into nitrogen (N2) and water (H2O).

[NH3] → N2 + H2O

Current ASC technologies are also able to convert NOx to nitrogen.

NOX + NH3 → N2 + H2O

Composition: Designed to include oxidation (typically Pd, Pt or Rh) and reduction functions (typically metal zeolite) coated on a flow-through monolith.

An exhaust system operating with an SCR catalyst is usually also equipped with a special catalyst providing a selective Ammonia (NH3) oxidation function.

Due to the dynamic driving cycle, recognizable amounts of NH3 leave the SCR. Therefore, the conversion of excess Ammonia leaving the SCR catalyst is mandatory, since Ammonia is also an emission regulated gas.

Oxidation of Ammonia leads to the formation of NO as main product, which would consequently contribute negatively to the total conversion of NOx of the whole exhaust system.

An ASC follows as smart catalyst design to mitigate the emission of additional NO. The catalyst combines the key NH3 oxidation function with an SCR function.

Ammonia entering the ASC is partially oxidized to NO. The freshly oxidized NO and NH3 inside the ASC, not yet oxidized, can consequently react to N2 following the usual SCR reaction schemes.

By intelligent system and catalyst design, combined with an adapted operation strategy, the ASC is capable of eliminating the traces of Ammonia and converting in parallel newly formed and existing NO to N2, which finally helps to reduce further NOx emissions.