SCR systems and Reagents

SCR systems and Reagents (Reducing Agents)

SCR technology in marine vessels requires a specific urea solution (urea solution 40%, also known as AUS40) to function and reduce NOx emissions. Yara can supply a quality reagent, produced to Yara’s high quality standards, anywhere in the world.

Read more about the availability of NOxCare 40 Marine, Yara’s urea reducing agent (AUS40) for use with Marine SCR.

How does the marine SCR system work with marine urea solution (AUS40)?

  • The SCR system is usually installed between the engine and the exhaust outlet, in some cases also pre-turbo.
  • Urea solution 40% is injected into the SCR system.
  • The exhaust gases pass through the SCR catalyst.
  • A chemical conversion takes place between the reagent and the NOx gases.
  • The NOx is converted into harmless nitrogen and water and emitted to the atmosphere.


NOxCare 40 Marine is sprayed into the exhaust gas, upstream of the catalyst where it is converted to ammonia. The ammonia mixes with the exhaust gas and reacts with the NOx molecules on the catalyst surface and form harmless nitrogen gas (N2) and water (H2O).

NOxCare 40 Marine