Diesel Retrofit Technologies

Emission control technologies include catalytic converters and particulate filters. They consist of a stainless steel box (or can) mounted in the exhaust system either as original equipment or retrofit emissions control device. In some retrofit applications, they can even be mounted in the original muffler.

Inside the can is an autocatalyst or a particulate filter. The autocatalyst can be a ceramic or metallic substrate with an active coating incorporating chemical compounds (the washcoat) to support a combination of catalytic metals or minerals selected for their effectiveness in the required emissions reductions. It can also be a homogeneous honeycomb-ceramics in which only active compounds are extruded simultaneously. The autocatalyst or the particulate filter is mounted in a can and is protected from vibration and shock by a resilient 'mat'. The emission control device then looks similar to an exhaust muffler. Typical emission control devices available for retrofit applications are Diesel Particulate Filters (DPF), Diesel Oxidation Catalysts (DOC), and Selective Catalytic Reduction (SCR) catalysts. They allow the reduction of Particulate Matter (PM) - soot particles - and NOx emissions from existing diesel engines and vehicles.

Combined systems to reduce both PM and NOx simultaneously are also available.

Fuel economy and CO₂ emissions should not be negatively impacted by the use of a retrofit emissions control device provided the system is properly designed for the particular applications.
Biofuels can affect engine-out emissions and performance; therefore, their impact should be evaluated before fitting a retrofit emissions control system on an existing vehicle.