Highly efficient WO₃-FeO_x catalysts synthesized using a novel solvent-free method for NH₃-SCR

Area of Science:

• Materials Science
• Catalysis
• Environmental Chemistry

Background:

• Selective catalytic reduction (SCR) is crucial for controlling nitrogen oxide (NOx) emissions.
• Ammonia (NH3) is a common reductant in SCR, but efficient catalysts are needed.
• Tungsten oxide (WO3) and iron oxide (FeOx) are known catalytic materials.

Purpose of the Study:

• To synthesize and evaluate WO3-FeOx catalysts for NH3-SCR.
• To investigate the effect of WO3 content on catalyst performance.
• To elucidate the reaction mechanism and structure-activity relationships.

Main Methods:

• Solvent-free synthesis of WO3-FeOx catalysts with varying WO3 content.
• Characterization using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS).
• In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for mechanistic studies.

Main Results:

• The optimal 30% WO3-FeOx catalyst exhibited superior NH3-SCR activity.
• Nearly 100% NOx removal efficiency was achieved between 225-500°C.
• WO3 introduction modified the electronic structure, forming Fe3O4 and enhancing adsorbed oxygen.

Conclusions:

• WO3-FeOx catalysts demonstrate excellent performance for NH3-SCR.
• Synergistic effects between WO3 and FeOx enhance NH3 adsorption and NOx activation.
• The reaction proceeds via a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms.