Selective Catalytic Reduction (SCR)

Depending on the NO/NO2 content in the exhaust gas, two important main Selective Catalytic Reduction (SCR) reactions are:

• Without NO₂: Standard SCR: 

4 NH₃ + 4 NO + O₂ → 4 N2 + 6 H₂O

• With NO₂: Fast SCR: 

4 NH₃ + 2 NO + 2 NO₂ → 4 N2 + 6 H₂O