SCR- ASC

 FAQ

1. What is an SCR-ASC catalyst?

An SCR-ASC catalyst combines Selective Catalytic Reduction (SCR) and an Ammonia Slip Catalyst (ASC) to reduce NOx emissions and minimize ammonia slip.

2. How does an SCR-ASC system work?

DEF generates ammonia, the SCR catalyst converts NOx into nitrogen and water, and the ASC oxidizes any remaining ammonia.

3. What is the difference between SCR and ASC?

SCR reduces nitrogen oxides (NOx), while ASC removes excess ammonia that remains after the SCR reaction.

4. Why is an ASC installed after an SCR catalyst?

ASC helps reduce ammonia slip by converting unreacted ammonia into harmless products under suitable operating conditions.

5. What catalyst materials are used in SCR-ASC systems?

SCR commonly uses copper-zeolite (Cu-SCR) or iron-zeolite (Fe-SCR) catalysts, while ASC uses catalysts optimized for ammonia oxidation.

6. Does an SCR-ASC system require DEF?

Yes. The SCR process requires ammonia generated from DEF, while the ASC functions without additional DEF injection.

7. How does SCR-ASC work with a DPF?

The DPF captures particulate matter, while the SCR-ASC module reduces NOx and controls ammonia slip as part of a complete exhaust aftertreatment system.

8. Is SCR-ASC available as an integrated module?

Yes. Depending on the application, SCR and ASC can be combined into a single integrated catalyst module or installed separately.

9. Which vehicles commonly use SCR-ASC systems?

SCR-ASC systems are widely used in trucks, buses, construction equipment, agricultural machinery, marine engines, generators, and other diesel-powered equipment.

10. Does an SCR-ASC catalyst require maintenance?

Routine inspection of the DEF system, injectors, sensors, and catalyst assembly is recommended according to the equipment manufacturer's maintenance schedule.