Selective Catalytic Reduction

AirProtekt supplies either the complete Selective Catalytic Reduction (SCR) package or the SCR catalyst for control of NOx emissions.

The catalyst technologies are all well proven and supported by the highest manufacturing and quality control standards from one of the leading catalyst manufacturers in the world.

The AirProtekt nitrogen oxide (NOx) removal process is a Selective Catalytic Reduction (SCR) technique that uses urea as the reducing agent.

The basic reactions break down the nitrogen oxides into harmless nitrogen and water. Ordinarily, the reactions require a long period of time to complete, so a suitable catalyst must be used to accelerate these reactions. The AirProtekt catalyst fulfils these requirements.

Urea is used as a reducing agent because it is generally unaffected by the oxygen present in the exhaust gases and is readily available.

In most exhaust gases, almost all of the NOx present is in the form of nitrogen oxide (NO). The optimum temperature for the reduction of the NOx using a zeolite/ base-metal catalyst is about 350-550°C

The SCR process benefits are:

  • NOx is reduced to harmless nitrogen and water vapour eliminating problems resulting from the generation of wastewater or solution;
  • The catalyst has a long life to provide a high NOX removal rate;
  • Extensive modifications to the engines are avoided.

The underlying principle of the SCR process is the use of ‘active’ catalytic sites on which the reactant species are adsorbed. The adsorption enables the combination of the reactant species at much lower gas temperatures than is required for uncatalysed reactions.