AirProtekt Ltd supplies either the complete SCR package or the SCR catalyst for control of NOx emissions. The catalyst technologies used are all tried and tested and backed up by the highest manufacturing & quality control standards from the largest automobile catalyst manufacturer in the world. The AirProtekt Ltd nitrogen oxide (NOx) removal process the Selective Catalytic Reduction (SCR) technique, which uses urea as the reducing agent.

The basic reactions that occur are as follows:

4 NH3 + 4NO + 02    ---> 4 N2 + 6 H2O

8 NH3 + 6 NO2    ---> 7 N2 + 12 H20

The above 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 Ltd catalyst fulfils these requirements.

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

In most exhaust gases, virtually 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 advantages of the SCR process are:

NOx is reduced to harmless nitrogen and water vapour. This eliminates problems resulting from the generation of wastewater or solution.
The catalyst has a long life and provides a high NOX removal rate.
Extensive modifications to the engines are avoided.
The underlying principle of this type of catalytic process is the use of 'active' catalytic sites on which the reactant species are adsorbed. This adsorption permits combination of the reactant species at much lower gas temperatures than required for uncatalyzed reactions.

AirProtekt has many years experience of providing the following solutions for a large number of international organizations including

Selective catalytic reduction (SCR)

Johnson Matthey
SGL Technic