The aim is to reduce the NOx emission through a chemical reaction. The SCR (Selective Catalytic Technology) decreases the NOX by splitting into two harmless parts such as Nitrogen and Water vapour. In BS-VI diesel engine, there is housing for the SCR which consists of Diesel exhaust fluid or AdBlue which bring down the NOX emission. Nowadays Diesel exhaust fluid is used for heavy vehicles because it emits larger toxic than diesel cars. AdBlue is using in most of the BS-VI compliant cars having around 10-12 liter capacity. The cost of the AdBlue is RS.126/kg.
Chemical reaction to reduce the NOX emission.
AdBlue is made up of urea and de-ionized water. The exhaust gas is reacted with AdBlue present in the SCR the urea is converted into carbon dioxide and ammonia. This ammonia is reacted with the NOX and it gets converted into water vapour and nitrogen. Therefore, the NOX emission is reduced drastically here.