Recent Progress on Low-Temperature Selective Catalytic Reduction of NO_x with Ammonia

Area of Science:

• Environmental Science
• Catalysis
• Chemical Engineering

Background:

• Ammonia selective catalytic reduction (NH3-SCR) is vital for controlling nitrogen oxides (NOx) emissions from stationary and mobile sources at temperatures above 300 °C.
• Current NH3-SCR catalysts are less effective at lower temperatures (<200 °C), hindering energy efficiency and adaptability to diverse fuel sources.

Purpose of the Study:

• To systematically review recent advancements in low-temperature NH3-SCR catalysts.
• To identify key factors influencing catalytic activity and stability under low-temperature conditions.

Main Methods:

• Literature review of recent research on low-temperature NH3-SCR catalysts.
• Analysis of the role of redox properties and surface acidity in catalytic performance.
• Discussion of strategies to overcome challenges posed by water and sulfur oxides.

Main Results:

• Catalyst redox properties and surface acidity are critical for low-temperature NH3-SCR activity.
• Strong redox properties enhance activity but can lead to undesirable nitrous oxide (N2O) formation.
• Water and sulfur oxides (SOx) significantly inhibit NH3-SCR performance, particularly at low temperatures.

Conclusions:

• Optimizing redox properties through multiple electron transfer systems is promising for low-temperature NH3-SCR.
• Enhancing catalyst hydrophobicity can mitigate water interference.
• Developing robust catalysts resistant to SOx poisoning is essential for practical applications.