Study On The Preparation And Performance Of The Rare Earth Doping Catalyst Of Iron-based For SCR

In view of the increasingly stringent NOx emission control standards, to adapt thesituation of our country, we should speed up the development of the Selective CatalyticReduction (SCR) denitration technology in power, in order to achieve low pollution, lowcost, high efficiency, etc. Fe2O3catalyst was chosen as the experimental substrate in thisexperiment, and the rare earth doping catalyst of iron-based SCR was prepared. Theeffects of elements doping on Fe2O3for low temperature SCR were studied. In order topromote medium-low temperature SCR activity of the catalysts, the scanning electronmicroscope (SEM) was used to observe the particle morphology. The pore structure wasanalyzed by N2adsorption instrument (BET). The thermal stability of the catalyst wastested by thermal analyzer (TG-DSC). The phase structure was analyzed by X-raydiffraction (XRD). The redox property of catalyst was analyzed by H2reduction program(H2-TPR), and also the SCR denitration activity of the catalyst was tested by thefixed-bed reaction device. The effects of rare earth doping on iron-based catalyst onthermal stability, SCR denitration activity and structure were studied, the results showthat:The final pH of the reaction is the most important factor for Fe-Ce catalystprecipitating from bicarbonate-ammonia system. Reaction temperature was the secondaryfactor. The mixed rare earth Ce could improve the gamma Fe2O3(γ-Fe2O3) to alphaFe2O3(α-Fe2O3) transformation temperature, and also improved the stability of γ-Fe2O3,thus greatly enhance the activity of catalyst in low temperature. When doping10%amount of Ce, the SCR denitration activity was the highest. The activity was93.8%at250℃. And catalyst prepared by roasting at400℃for5h has much smaller particle size,wider distribution, larger specific surface area and the highest SCR denitration activity.The catalyst composited with Fe-Ce-Y oxides was studied. The results show that thereduction temperature of the catalysts decreases with the doping of Y; made its pore sizesmaller, enhanced the BET surface area and pore volume of iron-cerium mixed oxide catalyst, increased the pores content, and made the catalyst surface activity centerincreasing, which is beneficial to the improvement of the catalytic activity. TheY-Ce/Fe2O3(k=1/2) showed the highest SCR denitration activity. The activity was94.5%.In Fe0.90Ce0.10-yLayOz(y=0.03,0.05and0.07) series catalyst, the doping of La couldobviously enhance the low-temperature SCR activity over iron-cerium mixed oxidecatalyst, and made its reactive temperature window of SCR shift to the low-temperatureregion. The catalyst of Fe0.90Ce0.07La0.03Ozshowed best SCR denitration performance.The activity was94.3%.