Study On Preparation Technology And Properties Of SCR Forming Catalyst

Nitrogen oxides are the main components of air pollution.Common nitrogen oxides mainly include nitrous oxide（N₂O）,nitric oxide（NO）and nitrogen dioxide（NO₂）.Excessive emission of these oxides not only causes serious damage to the environment,but also to animals,plants,buildings and buildings due to acid rain,has a detrimental effect on people’s travel safety,and destroys the ozone layer.Harm the immune system,respiratory system and cardiovascular and cerebrovascular system of the human body,and may lead to death in serious cases.However,Selective catalytic reduction（SCR）is the most efficacious way to eliminate nitrogen oxides.At present,the research laboratory of Mn-based catalyst has made great achievements in low temperature denitrification,but how to apply the powder catalyst prepared in the laboratory to the actual condition is still a difficult problem,so this theise mainly studies the preparation process and performance test of Mn-based SCR monolithic catalyst.（1）Study on coating technology and properties of monolithic SCR denitration catalyst.Catalysts for forming Mn Fe-S（Solution）,Mn Fe-P（Precursou）and Mn Fe-C（Catalysts）were prepared using cordierite as a carrier by different impregnations of metal ion salt solution,precursor body fluid and powder suspension.The morphology characteristics of the three catalysts were investigated by SEM,TEM and HRTEM,and the adhesion and structural properties of the surface active components of the three catalysts were studied by XRD,BET,XPS and Raman characterization.The experimental results show that,The integrated catalyst Mn Fe-S obtained by solution impregnation method has uniform distribution of active components and the largest specific surface area.By calculation and performance test,it has the highest loading capacity of 18.56%,and the conversion rate of NO is stable at 90%in the temperature range of 100-200℃,and has excellent sulfur resistance.（2）Exploration of integral catalyst forming process and comparison of denitration performance of NH₃-SCR.In this theise,mullite,Cordierite and activated charcoal were used as support,and after pretreatment,three monolithic forming catalysts,Mn Fe-M,Mn Fe-J and Mn Fe-A,were prepared by dipping and coating with solution.Through continuous adjustment and optimization of the preparation process,we obtained that when mulmulite carrier was treated with acid,the concentration of active component was 20%,the impregnation time was 3 h,the impregnation times was 1,and the calcination temperature was 500℃,the conversion rate of NO was 91%when the space velocity GHSV was 3000 h^-1 and 150℃.It also has excellent sulfur resistance.At the same time,the influencing factors of catalyst performance were calcination temperature>active component concentration>impregnation times>impregnation time.（3）Comparison of preparation technology and denitration performance of CO-SCR for monolithic catalyst.This theise mainly verified that the direct impregnation of metal ion salt solution was also suitable for the preparation of CO-SCR integral.The low-temperature denitration catalyst with good performance in the laboratory was scaled up to kilogram level,and the active components Ce O₂ and Cu O were combined to form Cu O/Ce O₂ catalyst and coated on the acid-treated mullite carrier by solution direct impregnation coating.A single catalyst with the size of 150×150×150 mm was prepared,and the concentration and loading capacity of active components were investigated.A set of core forming formula and process parameters were determined.The NO conversion rate of the prepared low temperature rare earth catalyst was greater than 50%when the flue gas temperature was 120℃.At 140℃,NO conversion rate is greater than 80%.