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Manganese–cerium mixed oxides supported on rice husk based activated carbon with high sulfur tolerance for low-temperature selective catalytic reduction of nitrogen oxides with ammonia
- Shu, Yun, Zhang, Fan, Wang, Hongchang
- RSC advances 2019 v.9 no.41 pp. 23964-23972
- Bronsted acids, X-ray diffraction, activated carbon, alkalinity, ammonia, catalysts, catalytic activity, manganese, nitrogen, nitrogen oxides, oxygen, rice, rice hulls, silica, sulfates, sulfur, sulfur dioxide, temperature
- A rice husk-derived activated carbon supported manganese–cerium mixed oxide catalyst (Mn–Ce/RAC) was prepared by an impregnation method and tested for the selective catalytic reduction of nitrogen oxides with ammonia (NH₃-SCR). 5 wt% Mn–Ce/RAC catalyst showed the highest activity, yielding nearly 100% NOₓ conversion and N₂ selectivity at 240 °C at a space velocity of 30 000 h⁻¹. Compared with commercial activated carbon supported manganese–cerium mixed oxide catalyst (Mn–Ce/SAC), a higher SCR performance with good SO₂ tolerance could be observed in the tested temperature range over the Mn–Ce/RAC catalyst. The characterization results revealed that the Mn–Ce/RAC catalyst had a higher Mn⁴⁺/Mn³⁺ ratio, amount of chemisorbed oxygen and more Brønsted acid sites than the Mn–Ce/SAC catalyst. The XRD analysis indicated that Mn–Ce oxides were highly dispersed on the RAC support. These properties of Mn–Ce/RAC assisted the SCR reaction. Moreover, in situ DRIFTS results demonstrated that sulfate species formation on Mn–Ce/RAC was much less in the presence of SO₂ than that of Mn–Ce/SAC, which might be ascribed to the reduced alkalinity of the catalyst by the presence of SiO₂ in RAC.