Preparation Of Sintering Dust SCR Catalyst And Study On Denitrification And Water And Sulfur Resistance

Nitrogen oxides（NO_x）is one of the common air pollutants causing atmospheric pollutant,and great sum of NO_xemissions will bring harm to human health and the environment.At present,with the energy saving policy and the total emission of atmospheric pollutants needs to be controlled to meet the increased stringent national standards.Considering iron and steel enterprise are one of the main sources of NO_xemission,and also emit some kind of pollution dust produced during sintering--sintering dust.Selective catalytic reduction（SCR）process is a high-efficient flue gas denitrification technology,and denitration catalyst with excellent performance is the key.The most mature V₂O₅-MO_x/TiO₂catalyst for commercial application is not only expensive but also has certain toxicity of metal vanadium.Therefore,the development of new non-polluting,low-cost and excellent SCR denitration catalyst has become a research hotspot in this field.In this study,sintering dust was used as raw material,doped and modified with different metal elements and loaded on different supports,and then nano sintering dust catalyst is prepared by hydrothermal method.The denitration activity,water and sulfur resistance were searched.The elemental composition,micromorphology,chemical state of each catalyst have been systematically studied using XRD,BET,SEM,XPS,particle size analysis and other characterization methods.The details are summarized as follows:（1）Research on the performance of sintering dust denitration catalyst modified by metal elements.Firstly,the raw materials are pretreated.HF treatment can not only stimulate the iron oxide activity of sintering dust,but also effectively dredge the pore structure.Then,Ce doping can further enhance the surface dispersion of the catalyst and improve the denitration performance.When doping 10wt%amount of Ce,10Ce/PSD_HFcatalyst(PSD_HFrepresents sintering dust after HF pretreatment)showed the best NO_xconversion,reaching76.4%at 280℃.（2）Performance study on supported sintering dust catalyst.Reaction performance of the different supported catalysts,which comprise the above-mentioned 10Ce/PSD_HFmaterial as active composition to carry out research.It was shown by characterization results of supported catalysts that activity component loading on ZrO₂has better denitration performance.The carrier has the strongest interaction with active component,the specific surface area increases,the active components are well uniformly dispersed on ZrO₂,a large amount of adsorbed oxygen in the surface of catalyst.The SCR denitration performance of catalyst increased when the loading increased and the desirable loaded amount was 25 wt%,the NO_xconversion rate of 0.25Ce₁₀-PSD_HF/ZrO₂catalyst reaches about 85%at 280℃.（3）Research on the performance of nano-modified sintering dust denitration catalyst.The research indicates that the Nano-Ce₁₀-PSD_HF/ZrO₂catalyst prepared by hydrothermal method not only with smaller particle size and evenly dispersed,but also forms a high concentration of Ce³⁺and adsorbed oxygen O_αon the surface,which is conducive to the SCR reaction.In the whole temperature range of 80-400℃,the denitration activity of the Nano-Ce₁₀-PSD_HF/ZrO₂catalyst prepared by the hydrothermal method was higher than that prepared by impregnation method,and the optimal denitration rate is about 93.6%at 280℃.（4）The water and sulfur resistance properties of the modified sintering dust catalyst were studied.The experimental result showed that the simultaneous addition of Ce and Zr can not only better inhibit the formation of ammonium sulfate on the surface of the catalyst,but also promote the decomposition of ammonium sulfate on the surface and reduce the blockage of pores,which has little effect on the denitration activity of SCR catalyst.At the reaction temperature of 280℃,after introducing 400ppm SO₂and 5%H₂O for 4h,the denitration efficiency of PSD-HF and 10Ce/PSD_HFcatalysts decreased by 46.7%and 24.2%respectively.The Nano-Ce₁₀-PSD_HF/ZrO₂catalyst shows the best water and sulfur resistance,the denitration activity declined by only 9.1%and still maintained about 85%.