scr selective catalytic reduction
Selective catalytic reduction (SCR) is a high-tech emission control technology developed to cut back nitrogen oxides (NOx) emissions from diesel engines. The primary function of SCR is to convert NOx by catalytic action rather than mechanically, with N2 and H2O as the products--both harmless to anyone living in this world. This process is based on an absorbent chemical reaction in which an aqueous urea solution, known as DEF (diesel exhaust fluid), is injected into the exhaust gas flow. SCR systems feature several leading technologies including a catalyst-coated substrate, DEF dosing unit and sensors monitoring exhaust gas quality. SCR technology is being taken more and more widely, appearing now in different segments including heavy trucks, buses and construction machinery. For these wards of the state, SCR can save a lot on emissions charges as they are increasingly required to meet ever stricter standards.