Research On Preparation And Performance Of Mn-Ce-Fe?Sn?/TiO₂-SiO₂-Al₂O₃ Catalysts For Removal Of NO_x

NO_x one of the main atmospheric contaminant may cause a variety of harmful effects on the ecological environment and human health,for instance,leading to the greenhouse effect,ozone layer destruction,dust-haze,acid rain and photochemical smog pollution et al.The selective catalytic reduction?SCR?technique has been widely applied due to the advantage of high technology maturation,high NOx reduction efficiency,simplicity of operation and high quanlity&reasonable price.In this study,by means of improving the carrier,doping additives,we developed a novel catalyst which has advantages:high low-temperature activity,wide activity temperature window on the basis of Mn-Ce.In this work,firstly,A series of Mn and Mn-Ce doped Ti O₂ catalysts were prepared by wet impregnation method successfully.Then,the effect of different manganese,cerium loading amount on catalytic performance were investigated.The results show that Mn?0.14?-Ce?0.06?/TiO2 catalyst exhibit the highest denitration activity,Mn/TiO2 catalyst doped with CeO₂ promoted the surface acidity and catalytic activity at low temperature.Two series composite oxide support TiO2-SiO2 and TiO2-SiO2-Al2O3 were synthesized by sol-gel method.Catalyst supports doped with Si and Al possess a large specific surface area and pore volume,especially,the specific surface area of TiO2-SiO2-Al2O3 could reach to500 m²/g.Then,a series of TiO₂-SiO₂ and TiO₂-SiO₂-Al₂O₃ supported Mn-Ce catalysts were prepared by impregnation method.The catalysts were characterized by XRD?BET?H₂-TPR?NH₃-TPD?XPS and Pyridine-FTIR.Characterization results implied that surface acidity,active temperature window,redox property,denitration activity could be enhanced.As the ratio TiO2:SiO2:Al2O3 closed to 4:1.5:0.7,catalyst showed better denitration activity from 150to 400 ^oC.Fe and Sn were chosen to doped in Mn-Ce active component as addition agent,Mn-Ce-Fe/TiO₂-SiO₂-Al₂O₃ and Mn-Ce-Sn/TiO₂-SiO₂-Al₂O₃ catalysts were prepared successfully.The characterization results showed that both Fe and Sn were useful for improving catalytic activity at low temperature and active temperature window.Compared with Fe,Sn worked better.When Sn doping amount reached to 4 wt%,65%NO conversion at 50^oC and above 90%NO conversion at 100-350^oC were obtained.When it came to Fe,3 wt%doping amount showed better facilitation for denitration activity at 150^oC.Finally,The service life experiment was carried out for 100 hours at 250^oC,both of them performed a favourable stability.