Reducing NOx with SNCR and SCR systems using Ammonia Solution

Ammonia Solution, also known as aqueous ammonia or ammonium hydroxide, is ammonia dissolved in water. It can be used directly with SNCR and SCR systems.

Ammonia solution is more secure to use than anhydrous ammonia since the vapour pressure is greatly reduced by the presence of water. With the correct storage, appropriate handling, this reducing agent can be safely used to control NOx. Yara has been safely producing and delivering ammonia for over a century from its factories across Europe  


For NOx control, Yara recommends the use of ammonia solution when possible.


Why choose Ammonia Solution as your reagent?

Ammonia Solution is safer to use than anhydrous ammonia since the vapor pressure is greatly reduced by the water.  Correctly handled and stored, it is a safe and efficient reagent for NOx treatment in emissions control technology for power plants/utilities.  

For control of NOx, when the use of anhydrous ammonia is not possible, Yara recommends the use of Ammonia Solution because:

  • It is more efficient than urea and safer than anhydrous ammonia, offering a good compromise.
  • The risks associated with the transport, storage and use of ammonia solution are significantly lower than with anhydrous ammonia as the ammonia is dissolved in water. This reduces the vapor pressure of the solution, which usually allows it to be stored at atmospheric conditions.
  • Ammonia Solution does not freeze.

Ammonia has advantages over Urea when lower NOx emissions are required :

  • Reduced tendency of formation of nitrous oxide and less carbon monoxide formation.
  • Greater effectiveness in high-temperature SNCR systems than Urea.
  • Reduced probability of fouling and corrosion in equipment downstream of the injection point.
  • Leakage issues that can occur with Urea Solution are avoided.

Safe and reliable deliveries 

Ammonia Solution transport methods include:

  • Tank truck
  • Railcar
  • Vessel / barge

We deliver the reagent of your choice from our unique network of plants offering a constant back-up in sourcing.