The SCRF® system integrates Selective Catalytic Reduction (SCR) with a soot filter – the next step for diesel NOx control.
The SCRF system for light duty diesel improves system compactness and, over the European drive cycle, warms up more quickly than an SCR downstream of a CSF (due to its closer proximity to the engine) enabling earlier NOx conversion.
The SCRF system allows improved thermal management of the catalyst on the vehicle, is technically a very demanding system and may require additional SCR/ammonia slip catalyst (ASC) to maximise NOx conversion.
For diesel cars, SCR is widely used to control NOx. Urea is injected into the exhaust and decomposes to ammonia, which is stored on the SCR catalyst. When NOx passes over the catalyst it reacts with the stored ammonia and reduces to nitrogen.
Johnson Matthey manufactures SCR coatings with copper, iron and vanadium based materials that can be applied to extruded monoliths. The coating can also be applied to the particulate filter, allowing for a more compact SCRF system.
Euro 6 diesel emissions legislation for passenger cars began in September 2014. Johnson Matthey's SCRF system, first developed and manufactured in Royston in 2012, helps vehicle manufacturers meet these demanding requirements.