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Ostwald process

Process description

In the Ostwald process, ammonia and oxygen are converted to nitrogen monoxide and water vapour in a reactor on a noble metal net catalyst. Subsequently, the reactor discharge is cooled in a condenser to a temperature at which the water condenses. Here, a part of the nitrogen monoxide reacts with water and oxygen to form an aqueous solution containing nitric acid, it also contains nitrogen oxides, in particular nitrogen monoxide, in dissolved form. The remaining gas mixture which does not dissolve is fed to an absorption tower, where part of the gaseous nitrogen oxide is reacted with oxygen and water to form nitric acid.


Gas application

Through oxygen enrichment of the liquid or gaseous phase, the plant capacity or reaction yield of the synthesis can be increased.


Messer solution

During the absorption process of nitric acid plants, the targeted supply of oxygen to specific points in the process results in a considerable increase in efficiency, resulting in significant savings in raw materials and improvements in environmental protection. Adding oxygen can also increase capacity.

Nitric acid plant with oxygen feed 



  • Significant NOx reduction before and after existing DeNOx plants
  • Considerable increases in capacity
  • Longer lifetime of existing DeNOx catalysts, requiring less frequent investments
  • Low investment costs
  • Additional flexibility of production capacities