Coupling Electrochemical NO Reduction with Selective Catalytic Reduction for Off-Gas Treatment Without External...

Area of Science:

• Environmental Chemistry
• Chemical Engineering
• Electrochemistry

Background:

• Nitrogen oxides (NOx) removal from industrial off-gases is critical for environmental protection.
• Traditional methods like Selective Catalytic Reduction (SCR) rely on external ammonia, while electrochemical nitrogen oxide reduction (NORR) faces efficiency challenges at low concentrations.
• Existing NOx abatement technologies require significant optimization for industrial applications.

Purpose of the Study:

• To develop a novel, integrated process combining NORR and SCR for enhanced NOx removal.
• To overcome the limitations of standalone NORR, particularly at low NOx concentrations.
• To reduce energy consumption and eliminate the need for external reducing agents in NOx abatement.

Main Methods:

• A hybrid process was designed, integrating electrochemical nitrogen oxide reduction (NORR) with selective catalytic reduction (SCR).
• NORR converts half of the NOx to ammonia (NH3) electrochemically.
• The generated NH3 is then utilized in the subsequent SCR stage to reduce the remaining NOx.

Main Results:

• The combined NORR-SCR process effectively addresses NORR's low-concentration limitations and SCR's reliance on external ammonia.
• Electrochemical NOx reduction electricity consumption is reduced by approximately 50%.
• Techno-economic analysis shows slightly higher initial costs than traditional SCR, but with potential for future cost reduction and improved sustainability.

Conclusions:

• The integrated NORR-SCR system presents a promising, electrified alternative for industrial NOx abatement.
• This approach offers enhanced sustainability by leveraging renewable energy and reducing chemical reductant dependency.
• Further catalyst optimization and process integration can lead to competitive economic viability compared to conventional methods.