Preparation Of Mn-Ce-O_x/TiO₂ Catalyst By Impregnation Method And Its Denitration Performance

The burning of fossil fuels and the emission of automobile exhaust have caused nitrogen oxides to cause a series of environmental problems such as the greenhouse effect,photochemical smog,acid rain,etc.,and endanger human health.In the treatment of NO_x,the traditional V₂O₅-WO₃（or Mo O₃）/TiO₂ SCR catalyst has been used commercially for stationary combustion sources,especially coal-fired power plants.However,these catalysts inevitably have problems such as the biological toxicity of some vanadium species,poor tolerance to alkali metals,relatively narrow operating temperature range and the formation of N₂O at high temperatures.In this regard,manganese-based low-temperature denitrification catalysts have become a research hotspot.This article focuses on the preparation of Mn-Ce-O_x/TiO₂ catalyst by impregnation and its denitration performance.（1）The denitration activity of the catalyst prepared by different impregnation orders of Mn and Ce is different.Among them,the Mn-Ce-O_x/TiO₂ catalyst prepared by co-impregnation has the best low-temperature denitration activity and resistance to water and sulfur.The characterization results of N₂ adsorption and desorption,XRD,XPS and H₂-TPR showed that the co-impregnated Mn-Ce/TiO₂ catalyst has the largest specific surface area,the highest surface contents of Mn⁴⁺,Ce³⁺,and chemisorption oxygen,and better synergistic interaction between Mn and Ce;all of these are the reasons for its higher low-temperature SCR activity.（2）Three different Mn-Ce-O_x/TiO₂ catalysts were prepared by ordinary impregnation,ultrasonic assisted impregnation and citric acid complex impregnation.It was found that the impregnation method has a great impact on the denitration performance of the Mn-Ce-O_x/TiO₂catalyst at low temperature.Among them,the catalyst prepared by the citric acid complex impregnation method reaches 100%NO_x conversion rate at 125 ^oC,and its sulfur resistance is better than that of the catalyst prepared by the other two methods.It is worth noting that 10%water vapor has little effect on it.Through characterization,it was found that large specific surface area,strong NH₃ and NO adsorption capacity,abundant ions on the surface that are beneficial to the reaction,and better NO oxidation performance are the reasons for the best performance.（3）MCT-CA has better resistance to Pb poisoning than the catalyst prepared by ordinary impregnation（MCT）.The characterization results reveald that the doping of Pb decreased the Mn⁴⁺,Ce³⁺,and Oαcontent on the two catalyst surfaces.In addition,according to the in-situ infrared characterization results,MCT-CA-Pb has stronger NH₃ and NO_x adsorption capacity than MCT-Pb catalyst.