Enhancement of Low-Temperature Catalytic Activity over a Highly Dispersed Fe-Mn/Ti Catalyst for Selective Catalytic Reduction of NO_x with NH₃

A novel Fe₂O₃-MnO₂/TiO₂ catalyst was synthesized using a conventional impregnation method assisted with ethylene glycol and used for NH₃-SCR. The catalyst exhibited superior low-temperature activity over a broad temperature window (100-325 °C), low apparent activation energy, and excellent sulfur-poisoning resistance. The characterization results revealed that the catalyst was greatly dispersed with smaller particles, and the partial doping of Fe into the TiO₂ lattice thereby led to the formation of the Fe-O-Ti structure, which could strengthen the electronic inductive effect and increase the ratio of surface chemisorption oxygen, resulting in the enhancement of NO oxidation and favoring the low-temperature SCR activity via a "fast SCR" process. The in situ FTIR analysis showed that the NO_x adsorption capacity was significantly improved due to the desired dispersion property, further helping both the SCR activity and reaction rate at low temperatures. The present work confirmed that more active sites can be provided on the catalyst surface by modifying the dispersity.