Preparation Of Transition Metal Doped Mn-based Catalyst And Denitrification Performance Investigation Of Low Temperature NH₃-SCR

Nitrogen oxide（NO_x）released by fossil fuel combustion causes acid rain,photochemical smog,PM2.5 and a series of problems,which have brought serious harm to people’s life and health.At present,ammonia selective catalytic reduction（NH₃-SCR）technology is one of the most effective denitrification methods.Therefore,the development of low temperature denitration catalyst with high activity,sulfur resistance,water resistance and stability has become a hot and difficult research.Manganese based catalysts have become the research focus of low temperature denitrification catalysts at home and abroad because of their good low temperature activity and excellent physicochemical properties.However,the catalysts also have some defects,such as narrow reaction temperature window,poor resistance to sulfur and water.To solve these problems,this paper will take manganese as the active component and add one or more transition metals in it,so as to improve the defects of manganese based catalyst and prepare manganese based catalyst with excellent denitration performance.In this paper,three new denitrification catalysts Mn₆Zr₁,Mn₆Zr_0.3Co_0.7and Mn Cu Zr0.15 were prepared by co-precipitation method.The denitrification performance of the catalyst was tested by NH₃-SCR at low temperature in an atmospheric fixed reaction bed,and the anti-poisoning performance of the catalyst was explored by adding SO₂and H₂O in the reaction atmosphere.At the same time,the physicochemical properties of the catalysts were studied by a series of characterization.Examples include X-ray diffraction,N₂adsorption-desorption,scanning electron microscopy,X-ray photoelectron spectroscopy,temperature-programmed desorption/adsorption,and in-situ diffuse reflectance infrared spectroscopy.The following conclusions are drawn:When one or more transition metals are doped in the manganese catalyst,the denitrification activity,sulfur and water resistance of the catalyst are significantly enhanced,and the reaction temperature window of the catalyst is widened.The results show that it is feasible to doping transition metals in Mn based catalysts.In addition,a series of characterization results showed that the transition metals doped into the Mn-based catalyst were highly dispersed on the surface of the catalyst and formed an amorphous structure.At the same time,the specific surface area of the catalyst was increased,and the active species(Mn⁴⁺species,adsorbed oxygen O_α,etc.)on the catalyst surface was increased.The reaction mechanism of Mn₆Zr_0.3Co_0.7catalyst was studied by in-situ diffuse reflectance infrared spectroscopy.It was found that the reaction mechanism of Mn₆Zr_0.3Co_0.7catalyst followed Eley-Rideal（E-R）and Langmuir-Hinshelwood（L-H）.