A green approach for preparation of MnFeTi Low-temperature NH3-SCR catalysts: utilizing spent V2O5–WO3/TiO2 Catalysts

V2O5–WO3/TiO2 catalysts are commonly used in industry to remove nitrogen oxides. However, spent V2O5–WO3/TiO2 are hazardous solid waste, and their improper disposal can lead to water and soil pollution risks. This study proposes a waste-to-resource approach that promotes the safe disposal of spent catalysts while reducing the production cost of denitrification catalysts. Specifically, vanadium-free low-temperature selective catalytic reduction catalysts are synthesized using spent catalysts. The optimized catalyst, named MnFeTi-22, exhibits a broad temperature activity range, with NO conversion exceeding 96 % from 100 to 300 °C. Even with 5 % H2O, the catalyst maintains a 95 % NO conversion (at approximately 200 °C). Characterization results confirm that the loading of TiO2 recycled from spent catalysts onto MnFe significantly optimizes the distribution of active species. Furthermore, TiO2 can adjust the distribution of acidic sites and the quantity of surface-adsorbed oxygen, promoting electron transfer between Mn4+/Fe2+ and Mn3+/Fe3+.