The effect of rare earth modification on the denitration performance of Fe2O3–MnO2/TiO2 catalysts

Abstract

High denitration efficiency and strong adaptability to flue gas temperature fluctuations are essential properties for NH₃ selective catalytic reduction (SCR) catalysts. In this study, rare earth oxide modification of the catalyst 8Fe₂O₃–40MnO₂/TiO₂ via the addition of CeO₂ during the preparation process is explored. The results show that the 8Fe₂O₃–6CeO₂–40MnO₂/TiO₂ catalyst has excellent denitration properties, with a denitration efficiency of greater than 90%. The operational temperature range reaches 129 to 390 °C, and its N₂ selectivity, anti-SO₂ performance and anti-H₂O performance are good, with the denitration performance being significantly improved. The addition of 6% CeO₂ promotes the lattice shrinkage of TiO₂, improves its dispersion, refines the grain size, and increases the specific surface area of the catalyst. At the same time, CeO₂ increases the chemical adsorption of oxygen on the catalyst surface and the proportion of low-valence metal ions, promotes electron transfer between active elements, generates more surface reactive oxygen species, and increases the content of oxygen vacancies and adsorption sites for NO_x and NH₃. It also significantly improves the redox performance of the catalyst, which is especially conducive to the generation of weak and medium-strong acidic sites on the catalyst surface. The NH₃-SCR reaction on the surface of the 8Fe₂O₃–6CeO₂–40MnO₂/TiO₂ catalyst follows both L–H and E–R mechanisms, with the L–H mechanism being dominant.