Removal of NO_x at low temperature over mesoporous α-Mn₂O₃ catalyst

Low-temperature selective catalytic reduction was carried out over various kinds of manganese oxide (MnOx) catalysts. Mesoporous α-Mn ₂O₃, commercial bulk Mn₂O₃, and Mn/SBA-15 were used as the catalyst. The NOx removal performances of the catalysts were compared. Three different amounts of Mn (5, 10, and 15 wt%) were impregnated on SBA-15 to synthesize Mn/SBA-15. The physical and chemical properties of the catalysts were examined by Brunauer-Emmett-Teller, X-ray diffraction, X-ray photoelectron spectroscopy, and H₂-temperature programmed reduction analyses. Of all catalysts examined, mesoporous α-Mn₂O₃ exhibited the highest low-temperature SCR de-NOx efficiency, reaching about 90% at 175 °C. This is attributed to strong reducing ability and high oxygen mobility of mesoporous α-Mn ₂O₃ and well dispersed Mn₂O₃ in its mesoporous framework.