A highly efficient catalyst of a Co_aMn_bO_x mixed oxide prepared by the co-precipitation method was developed for the selective catalytic reduction (SCR) of NO_x with ammonia. With an increase in the Mn content, the catalytic activity of the Co_aMn_bO_x mixed oxide exhibited a volcano-type tendency, and when Co/Mn molar ratio reached 7:3 (Co₇Mn₃O_x), the operation temperature for achieving >80% NO_x conversion was 170 °C (116–285 °C window). The formation of spinel structured MnCo₂O₄ is highly important, and the presence of the spinel structure in Co₇Mn₃O_x contributes to the increase in active sites and thermal stability and promotes SO₂ and/or H₂O resistance. In comparison with MnO_x or CoO_x alone, the Co_aMn_bO_x catalysts possess improved redox properties and more surface acid sites due to synergistic effects between the Co and Mn species. Among the Co_aMn_bO_x catalysts with different Co/Mn molar ratios, a higher NH₃ and NO + O₂ adsorption ability was found for the Co₇Mn₃O_x catalyst, originating from its MnCo₂O_4.5 phase and higher surface area, which leads to the higher activity of the Co₇Mn₃O_x catalyst. In situ DRIFTs indicated that bridging nitrate and bidentate nitrate are the intermediate species in the NH₃-SCR reaction, and the high NO adsorption ability and improved redox properties of the Co₇Mn₃O_x catalyst are beneficial for the formation of nitrate species on the catalyst surface. Furthermore, NH₃ species adsorbed at Lewis acid sites taken part in SCR reaction, while the reactivity of NH₃ species adsorbed at Brönsted acid was not definitized.

开发了一种通过共沉淀法制备的高效Co _a Mn _b O _x混合氧化物催化剂，用于将NO _x与氨选择性催化还原（SCR）。随着Mn含量的增加，Co _a Mn _b O _x复合氧化物的催化活性呈现出火山型趋势，当Co / Mn摩尔比达到7：3（Co ₇ Mn ₃ O _x）时，操作温度实现> 80％的NO _X转化率是170℃（116-285℃的窗口）。尖晶石结构的MnCo ₂ O ₄的形成Co ₂ Mn ₃ O _x中尖晶石结构的存在有助于活性位点的增加和热稳定性，并提高了对SO ₂和/或H ₂ O的抵抗力。与单独的MnO _x或CoO _x相比，由于Co和Mn物种之间的协同作用，Co _a Mn _b O _x催化剂具有改善的氧化还原性能和更多的表面酸位。在具有不同Co / Mn摩尔比的Co _a Mn _b O _x催化剂中，较高的NH ₃和NO + O ₂发现Co ₇ Mn ₃ O _x催化剂的吸附能力源自其MnCo ₂ O _4.5相和较高的表面积，这导致Co ₇ Mn ₃ O _x催化剂的活性更高。原位DRIFTs表明硝酸盐和硝酸齿状硝酸盐的桥接是NH ₃ -SCR反应的中间物种，Co ₇ Mn ₃ O _x催化剂的高NO吸附能力和改善的氧化还原性能有利于在NH ₃ -SCR反应中形成硝酸盐物种。催化剂表面。此外，NH ₃路易斯酸位点上吸附的NH ₃物种参与SCR反应，而布朗斯台德酸上吸附的NH ₃物种的反应性尚未确定。