Using the impregnation method, a series of Cu–Mn oxide catalysts were prepared and investigated for the selective catalytic reduction (SCR) of NO_x with NH₃ at temperatures ranging from 353 K to 453 K. The 0.05Cu–MnO_x/TiO₂ catalyst shows the highest activity and yields nearly 100% NO_x conversion at 453 K using GHSV = 40 000 h⁻¹, while the 0.20Cu–MnO_x/TiO₂ catalyst exhibits a certain level of potassium tolerance. In addition, the catalysts show favorable stability and water resistance. According to the XRD, EDS and SCR performance results, the existence of a new crystallized CuMn₂O₄ spinel phase is the dominant parameter for outstanding SCR activity between 413 K and 453 K. TPR, XPS and in situ DRIFT experiments indicate that CuMn₂O₄ is responsible for low reduction temperature, strong interaction between manganese oxides and copper oxides, high Mn³⁺ content and numerous acid sites on the surface. Compared with MnO_x/TiO₂ catalysts, Cu–Mn oxide catalysts could reduce the poisoning effect of potassium, illustrating that the CuMn₂O₄ phase may play a significant role in K-tolerance. Meanwhile, based on a certain level of potassium tolerance in CuMn₂O₄, an oxidation mechanism for NO is proposed due to the increase in Mn³⁺ and the special structure of a spinel oxide.

Based on the temperature and O₂ concentration in the cement precalciner, co-combustion of anthracite and Refuse Derived Fuel (RDF) were investigated using a thermogravimetric analyzer (TGA) and a double furnaces reactor. Both the TGA and double furnaces reactor results indicated that the co-combustion characteristics were the linear additive effect in the devolatilization stage, while it was the synergistic effect in the char combustion stage. During co-combustion, at 900 °C, NOx released rapidly during the devolatilization stage, but in the char combustion stage the NOx formation were inhibited; at 800 °C, a large amount of CO formed, which could reduce the NOx. In general, at 900 °C and 800 °C, the application of co-combustion could lower the NOx emission yield and lower the NOx conversion. By combining the combustion characteristics with the XRD results, it was indicated that during co-combustion, at 800 °C, the SO₂ formation reaction was inhibited, and the SO₂ yield and conversion were quite low.

MnO_x/TiO₂ catalysts doped with sodium were prepared using the impregnation method. According to the results of the selective catalytic reduction (SCR) of NO with NH₃, sodium had the strong poisoning effect on MnO_x/TiO₂ catalysts for NO decomposition. With the help of XRD, H₂-TPR, NH₃-TPD, TGA and FESEM, the structures and properties of the catalysts were characterised. Results indicated that the addition of sodium would weaken the role of active ingredients in the SCR process. Meanwhile, the reduction peaks of MnO_x/TiO₂ catalysts doped with sodium slightly shifted to higher temperatures with increasing content of sodium, attributing to the sintering of MnO_x and sodium oxides. Based on the FESEM images, some larger particles were observed on the surface after sodium doping, which might be attributed to compounds of sodium manganese oxides. It could be concluded that the addition of sodium decreased the SCR activity of catalyst by slashing electron donation from the MnO_x active site.