Study On Preparation And Performance Of Mn/Al₂O₃-TiO₂ System Catalyst For Low Temperature SCR

Coal is the first source of energy in China,and nitrogen oxides（NOx）produced by coal combustion is one of the main causes of air pollution.Selective catalytic reduction（SCR）is widely used all over the world to remove the NOx in the flue gas.However,domestic SCR technology is usually used with high temperature,which causes low NOx removal rate but with high energy consumption and economic cost.Therefore,the study of catalyst used at a lower temperature SCR is very important for the treatment of haze and improvement of air quality.The main work of this topic is as follows:（1）Al2O3-TiO₂ used as composite oxide carrier was prepared by mechanical mixing and coprecipitation.The carrier was calcined at 400℃,500℃,600℃,700℃ and 900℃ respectively.The crystal phase,specific surface area and pore structure of the calcined products were analyzed.（2）It was analyzed that the effect of Mn concentration on the denitration activity of the Mn/Al2O3-TiO₂ catalyst with the condition of that MnOx prepared by impregnation was used as the main active component,nitrogen（N2）was used as the balance gas,the concentrations of nitrogen monoxide（NO）,ammonia（NH3）and oxygen（O₂）were 500 ppm,500 ppm and 5%respectively,and the reaction temperature was 80～280℃.（3）Fe,Co,Cr,Ce and Cu were used to study the effect of metal doping on the activity of Mn/Al2O3-TiO₂ catalysts.（4）The catalytic performance of Cu and Mn content in the Mn-Cu/Al2O3TiO₂ catalyst was investigated.Through the experiments and studies,the following conclusions were drawn:（1）As the catalyst carrier,the Al2O3-TiO₂ calcined at 600℃ has the highest thermal stability,largest specific surface area and best pore structure.（2）The denitrification activity of the Mn/Al2O3-TiO₂ catalyst reaches maximum when the Mn content is 15%.（3）The catalytic performance of Mn-Cu/AlO3-TiO₂ is better than the catalysts doped with the other metal element.The Mn presents in the catalyst in the form of MnO₂ when the Cu is doped.（4）The removal efficiency of NO could be as highest as 95%at 180℃when the mass ratio of Cu/Mn and the volume ratio of NH3/NO are 0.6 and 1.0 respectively.