Effect of Mn or Fe on CrMoOx /TiO2 selective catalytic reduction catalyst

Abstract

Developing a high-efficiency catalyst with both superior low-temperature activity and good sulfur and water resistance is still challenging for the NH3 selective catalytic reduction (SCR). Herein, a series of Mn- and Fe-doped CrMoOx/TiO₂ catalysts were elaborately designed and the Cr₃Mo₆Mn₂/TiO₂ catalyst exhibits the best NO_x conversion rate, reaching 81. 8 % at 90 ℃ and closing to 100 % at 150 ℃, and the NO_x conversion reach ∼71 % at 150 ℃ for 30 h in presence of H₂O+SO₂. A series of characterization studies revealed that the abundance of Lewis acidic sites on the catalysts and the protective effect of Mo are conducive to the enhancement of SO₂+H₂O resistance. cr₃Mo₆Mn₂/TiO₂ dominates the SCR reaction through the Eley-Rideal (E-R) pathway between adsorbed NH₄⁺/NH₃ and gaseous NOx, generating N₂ and H₂O. This work provides a new strategy for improving the tolerance of chromium-based oxide catalysts to sulfur dioxide and water at low temperatures.