Study On The Performance Of Fe-Ti Supported Low-Temperature Denitration Catalysts With Different Metal Ions

The SCR method is one of the most extensive and effective methods for removing NO_x,and the catalyst is the core of this method.At present,commercial catalysts based on V₂O₅/TiO₂ series have been formed,but the active temperature is320-450℃and the high-temperature and high-dust arrangement is adopted.Dust,SO₂ and water vapor in the flue gas will affect the catalytic activity of the catalyst.As a result,the catalytic efficiency of the catalyst is reduced or even deactivated.In this paper,the preparation conditions and denitrification performance of high-efficiency catalysts are studied under low temperature（80-200℃）and low dust.The catalysts with Mn O_x as the main active center have shown good denitration activity under the low temperature NH₃-SCR denitration reaction.At the same time,TiO₂ has a certain mesoporous structure which is conducive to the dispersion of ac tive components of the catalyst;Sponge iron（Fe）contains about 92%pure iron,and no pulverization,large specific surface area,low price and many other advantages.Therefore,in this research,low-temperature SCR catalyst were prepared with TiO₂ as carrier and doped with Mn,Ce,Fe,etc at 400℃for 5h.The low-temperature removal of NO_x activity,sulfur resistance and catalytic activity of the regenerated catalyst after poisoning were studied.The catalyst was characterized by BET,XRD,SEM and FT-IR instruments,and the physical and chemical properties of the catalyst were evaluated and analyzed.conclusion as below:The denitration efficiency of a 0.28Mn/TiO₂ catalyst with TiO₂ as the carrier and a Mn loading of 0.28 is up to 54.24%at 200℃.On this basis,the denitration efficiency of the 0.25Fe-0.28Mn/TiO₂ catalyst is up to 57.67%at 160℃.When Ce is doped alone,the denitratio n efficiency of 0.28Mn-0.16Ce/TiO₂ catalyst is up to 71.43%at 200℃.When Fe and Ce coexist,the denitration efficiency of0.28Mn-0.16Ce-0.15Fe/TiO₂ catalyst can reach 79.41%at 200℃.It shows that when Fe or Ce is doped alone,although both can improve the catalytic activity of the catalyst,it cannot improve the denitration efficiency of the catalyst to the greatest extent（The best denitration efficiency when Fe and Ce exist alone is 57.67%and71.43%respectively）.When Fe and Ce are present at the same time,the low temperature activity of the catalyst is significantly improved.Combined with BET,FT-IR,SEM and other characterizations,it was found that the addition of an appropriate amount of metal can inc rease the specific surface area of the catalyst,among which the 0.28Mn-0.16Ce-0.15Fe/TiO₂catalyst has the largest pore volume and pore diameter,0.881 cm³/g and 34.349 nm,with a larger specific surface area of24.376 m²/g;larger pore volume,pore size,and specific surface area help the catalyst and the gas to be fully contacted,thereby improving the denitration efficiency.Compared with 0.28Mn/TiO₂ catalyst,it is found that the catalytic activity of Fe-doped 0.25Fe-0.28Mn/TiO₂ catalyst has has increased to 57.67%,but its anti-sulfur effect is poor.When SO₂ is introduced,the catalytic efficiency decreased by 22.16%;After adding Ce,the catalyst’s denitration performance and anti-sulfur performance have been improved,but the catalytic activity of t he catalyst cannot be maximized.For example,the 0.28Mn-0.16Ce/TiO₂catalyst has an optimal denitration efficiency of 71.43%.After SO₂ is introduced,the denitrification activity decreased by18.68%,it can be seen that after adding Ce to the catalyst,the catalytic activity and sulfur resistance of the catalyst have been improved.When Fe and Ce are present at the same time,such as 0.25Fe-0.28Mn-0.16Ce/TiO₂catalyst,the best denitration efficiency reaches 73.03%,and after the introduction of SO ₂,the reduction of denitration activity is also less than 0.28Mn-0.16Ce/TiO₂ The catalyst is 15.35%,indicating that when both are present,it can both improve the catalytic activity of the catalyst and enhance the sulfur resistance of the catalyst.Combining characterization methods such as SEM,XRD,BET,and FT-IR,the phenomenon of agglomeration and collapse of pores on the surface of the catalyst after poisoning caused the catalyst’s catalytic activity to decrease.The catalyst was subjected to ultrasonic washing and regeneration,and low-temperature denitration experiments were conducted under the same atmosphere conditions.It was found that the denitration efficiency of each catalyst after regeneration was improved relative to the efficiency of the ca talyst after poisoning,but the catalytic activity was lower than that of fresh catalyst.For example,the optimal denitration efficiency after regeneration of the 0.28Mn-0.16Ce-0.15Fe/TiO₂catalyst increased from 56.05%to 62.03%After poisoning,but was lower than the optimal denitration efficiency of 79.41%for the fresh catalyst.Combined with the results measured by the flame atomic absorption spectrometer,it is speculated that it may be that the catalyst will wash away the toxic substances（sulfate,ammonium sulfate）and the active components（Mn,Ce）etc.Wash off some.Therefore,the catalytic activity of the catalyst after regeneration is lower than that of the fresh catalyst,but higher than that of the catalyst after poisoning.At the same time,the sources,economy and performance of 0.28Mn-0.16Ce-0.15Fe/TiO₂ and0.25Fe-0.28Mn-0.16Ce/TiO₂ catalysts were analyzed and compared,and it was found that 0.28Mn-0.16Ce-0.15Fe/TiO₂catalyst has better catalytic effect,sulfur resistance,regeneration effect and lower cost.