The document discusses selective catalytic reduction (SCR) technology for reducing NOx emissions. SCR uses a catalyst and reductants like ammonia or urea to convert NOx into nitrogen and water, reducing emissions by 70-95%. Zeolite-based catalysts like copper-zeolite and iron-zeolite are most effective at meeting regulations while minimizing ammonia slip. SCR is the leading NOx reduction technology due to its high performance and ability to reduce NOx without engine modifications.

1. Reduction of NOX- SCR technology
-By M.Amulya
Mechanical-III
AITS
Rajampet.

2. Contents:
•Effects of NOX
•Introduction to SCR
•SCR chemistry
•SCR catalysts
•Working
•Advantages
•Limitations
•Conclusion

3. Effects of NOX:
• Inhalation of NOX particles causes respiratory
diseases such as Bronchitis and Emphysema.
•NOX particles causes depletion of Ozone layer.
•It reacts with organic chemicals to form harmful
compounds which causes biological mutations.
•It is the main reason for the occurrence of Acid rains.

4. Introduction to SCR
•SCR means Selective Catalytic Reduction.
•It is the means of converting oxides of Nitrogen
to atomic Nitrogen and water.
•It reduces the NOX emissions by nearly 70-95%.
•It meets the standards of EURO VI and US 2010.
•It is the leading technology for reduction of NOX.

5. SCR chemistry:

6. SCR catalysts:
•Vanadium-based SCR catalyst.
•Zeolite SCR catalyst
Cu-Zeolite (CuZ)
Fe-Zeolite(FeZ)
SCR reductants:
Several reductants are currently used in SCR
applications including:
•Anhydrous Ammonia
•Aqueous Ammonia
•Urea

7. Vanadium-based SCR catalyst:
The V-SCR catalyst consists of Vanadium pentoxide
and Tungsten trioxode .At higher
temperature beyond 800k, toxic compounds may
release from the catalyst. Also the performance of
this catalyst is poor.
Zeolite catalyst:
Cu-Zeolite and Fe-Zeolite are preferred due to
their outstanding deNOX activity, temperature
durability .

8. These catalysts are placed in catalytic converter which
converts toxic pollutants to less toxic pollutants by
catalysing a redox reaction.
•2NOx → xO2 + N2
•2CO + O2 → 2CO2
•CxH2x+2 + [(3x+1)/2]O2 →
xCO2 + (x+1)H2O.
Reactions in a
Catalytic Converter:

9. Installation of catalytic converter in
vehicles:

10. Working:

12. When compared with other technologies, SCR is the
effective one to reduce NOX.

13. Difference in NOX levels before and after SCR:

14. Advantages:
•This does not require any modifications to the
combustion unit.
•Higher NOX reduction is possible.

15. Disadvantages:
•In SCR systems, Ammonia slip may occur.
•Large volumes of reductant and catalyst are
required.

16. Conclusion:
The SCR technology is the dominating deNOX
technology to meet the current and future NOX
emission regulations. To meet the current US
2010 and EURO VI regulations, Zeolite based
SCR catalysts are required.
With the increasing more and more
stringent emission standards, it is very much
necessary to improve and implement such
technologies.