Ostwald Process

Manufacturing of Nitric Acid HNO3

Step 1: Catalytic oxidation of ammonia:

  • Synthesis of NO by means of PtRh catalyst gauzes:
    4 NH3 + 5 O2 ⇒ 4 NO + 6 H2O
  • Formation of N2O is a side reaction that can’t be completely avoided:
    4 NH3 + 4 O2 ⇒ 2 N2O + 6 H2O
  • Temperatures of about 800 to 950°C
  • Pressure in the range between 1 and 15 bar
  • Contact time of gas mix with catalyst in the range of 1/1.000 sec

 

Step 2: Generation of Nitrogendioxide and dimerisation

  • 2 NO + O2 ⇒ 2 NO2 ⇒ N2O4

Step 3: Oxidation and absorption in column to yield final product

  • 2 N2O4 + O2 + 2 H2O ⇒ 4 HNO3