Low-temperature catalytic oxidation of NO over Mn–Co–Ce–Ox catalyst

A series of manganese–cobalt–cerium oxide (Mn–Co–Ce–Ox) catalysts were prepared by co-precipitation method and tested for low temperature (<200 °C) catalytic oxidation of NO in the presence of O2. The experimental results showed that the best catalyst yielded about 80% NO conversion at 150 °C with a space velocity of 35,000 h−1. As the cerium content was increased from 0% to 20% (mass%), NO conversion increased significantly, while decreased at higher cerium contents (30–40%). As comparison, single oxides were also investigated, and their activities were slower than those of Mn–Co–Ce–Ox catalyst. The effect of O2 (0–11%) was evaluated, and it is almost constant when the concentration of O2 was above 3%. The activity was suppressed with the coexisting of H2O and SO2 due to the generation of nitrates and sulfates, and the activity was restored to 45% after turning them off. The excellent low-temperature catalytic activity is mainly due to the amorphous phase, pore structure and high specific areas.

Graphical abstractThe best Mn–Co–Ce(20)–Ox-400 catalyst yielded 80% NO conversion at 150 °C. From the XRD, no sharp diffraction peaks emerged after Ce doping at a calcination temperature of 400 °C. The excellent low temperature catalytic activity of catalysts is mainly due to their amorphous phase and high dispersion.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Mn–Co–Ce(20)–Ox-400 catalyst yielded 80% NO conversion at 150 °C, the low-temperature activity was notable. ► The catalysts were characterized by XRD, BET and FT-IR methods. ► The catalysts had high resistance of H2O. ► NO conversion would be restored to 45% after removing H2O and SO2 gases.