Improved NO Reduction over Phosphate-Modified Fe₂O₃/TiO₂ Catalysts Via Tailoring Reaction Paths by In Situ Creating...

Area of Science:

• Catalysis
• Environmental Chemistry
• Materials Science

Background:

• Alkali poisoning is a major challenge for selective catalytic reduction (SCR) of nitrogen oxides (NOx) using ammonia (NH3).
• Existing catalysts often suffer deactivation in the presence of alkaline metals, limiting their practical application.

Purpose of the Study:

• To develop a phosphate-modified Fe2O3/TiO2 catalyst with improved resistance to alkali poisoning for NOx reduction.
• To understand the mechanism by which phosphate modification enhances catalyst stability and activity.

Main Methods:

• Synthesis of phosphate-modified Fe2O3/TiO2 catalysts.
• Characterization of catalyst structure, acidity, and redox properties.
• Evaluation of NOx reduction performance in the presence of alkali metals.

Main Results:

• Phosphate modification led to the formation of iron phosphate species (FePO4), enhancing alkali resistance and widening the operational temperature window.
• The modified catalyst exhibited increased surface acidity due to tetrahedral [FeO4]/[PO4] structures and improved redox ability with enhanced surface adsorbed oxygen.
• Phosphate groups acted as preferential binding sites for alkali metals (potassium), protecting active iron species and maintaining NOx reduction activity via the Langmuir-Hinshelwood pathway.

Conclusions:

• Phosphate modification is a novel strategy to design highly alkali-resistant catalysts for NOx emission control.
• The enhanced NH3 adsorption, redox properties, and protection of active sites contribute to the superior de-NOx performance of the modified catalyst.
• This approach offers inspiration for developing next-generation catalysts to mitigate NOx pollution.