The Modified TiO₂ Supported Fe-Mn Catalyst For NO Removal

As the implementation of new environmental standards,the denitration of coke oven flue gas has become a research hotspot.The key problem of denitrification is to develop the catalysts at low temperature in the presence of SO2 and H2 O.The Fe-Mn/TiO2 catalysts have an excellent activity at low temperature.However the activity of catalysts is low in the presence of SO2 and H2 O,or even inactivated.It is expected that increasing the specific surface area and surface acidity of TiO2 could improve the activity of the catalysts.Therefore,Fe and Cu are used to modify the TiO2,and then Fe-Mn is impregnated as the active component to obtain the catalysts.The Fe doped TiO2 is prepared to obtain catalysts,the effect of Fe/Ti(molar ratio)on the activity of catalysts is studied.It's found that Fe/Ti=0.05,at [NO]=[NH3]=0.1%,O2 7%,N2 as the balance gas,GHSV=10000~45000 h-1,the catalyst shows early 100% NO conversion over 170 ?.The sulfur and water resistance of Fe-Mn/TiO2(0.05Fe)catalyst at 200 ? with 0.01% SO2 and 10% H2 O are investigated.95% NO conversion is kept in 4 h,which is 11% higher than that of unmodified catalyst.The catalysts are characterized by N2 adsorption-desorption?XRD?H2-TPR?XPS?NH3-TPD and TG methods.It's found that Fe-modifition increases the defects of lattice oxygen and surface acidity of catalysts.The ratio of Fe3+ and Mn4+ is increased,which is favor to improve the activity of catalysts.High specific surface area,more defects of lattice oxygen and acid sites are the main reasons to improve the sulfur and water resistance of catalysts.Cu is used to modify the catalysts,the effects of Cu amount on the activity and the resistance to sulfur and water are investigated.The results show that Cu modifition improves the activity of catalysts below 200 ?.With the n(Cu/Ti)=0.01,the catalyst reaches 100% NO conversion at 170 ?.The activity of Fe-Mn/TiO2(0.01Cu)can keep 88.5% in 4 h at 200 ? with sulfur and water existence.The increase ratio of Mn4+,Fe3+ and Cu2+ and the weak acid sites of the catalysts are the main reasons for the high activity and high sulfur and water resistance at low temperature.