Selektive Catalytic NOx Reduction (SCR)

The nitrogen oxides (NOx) are reduced by the SCR process (selective catalytic reduction). The exhaust gas treated with with a reactant (urea or ammonia) passes through honeycomb-patterned convertors with a fine cell structure. The nitrogen oxides react ith the reactant on the active surface of the convertor and are reduced to water and nitrogen.

Nitrogen oxides irritate and harm the respiratory system. Also, they are responsible for acid rain and contribute to ozone and smog.