Enhancement of SO₂ Resistance on Submonolayer V₂O₅–MnO₂/CeO₂ Catalyst by Three-Dimensional Ordered Mesoporous CeO₂ in Low-Temperature NH₃–SCR

Developing low-temperature (<300 °C) SO 2 -tolerant catalysts for NO x reduction is a challenge. A catalyst architecture of three-dimensional (3D) ordered mesoporous CeO 2 supported by submonolayer V 2 O 5 and MnO 2 (V 2 O 5 –MnO 2 /3D-CeO 2 ) was successfully prepared to promote the SO 2 resistance in low-temperature selective catalytic reduction (SCR). The 3D ordered mesoporous channels were retained even after the exposure of the catalyst to SO 2 and H 2 O. The presence of a highly 3D ordered mesoporous structure of V 2 O 5 –MnO 2 /3D-CeO 2 can lead to high vapor pressure, which was beneficial for ammonium bisulfate vaporization and decomposition, eventually protecting the active vanadia sites. The stable active crystalline V 2 O 5 species and the formative cerium sulfate promoters were crucial for determining the low-temperature SCR activity and SO 2 tolerance in the presence of SO 2 and H 2 O. Therefore, our V 2 O 5 –MnO 2 /3D-CeO 2 catalyst delivered a large temperature range of 250–320 °C with NO conversion above 95%. The 3D ordered mesoporous channels of the V 2 O 5 –MnO 2 /3D-CeO 2 catalyst provided an effective way to improve the SO 2 resistance at 250 °C.