Study Of SCR Denox Catalyst Supported On Al₂O₃-TiO₂-ZrO₂

The research of catalyst is the most important part of SCR technology, the carrierwhich determines the performance and life of catalyst is an important component ofcatalyst, and the research of carrier is the key of SCR catalyst. The support material ofcommercial catalysts was a pure metal oxide which still had some defects in thepractical application, regulation of the composite oxides could make up for thesedeficiencies, and then further improve the research of denitration catalyst. TheAl2O3-TiO2-ZrO2composite oxides with large specific surface area, surface acidity,wide distribution of strong acidity and high stability, could be used as excellent supportmaterial.In this dissertation, with Al2O3-TiO2-ZrO2composite oxides as catalyst supports,SCR catalyst for coal-fired gas denitrification was investigated systematically. Thewhole dissertation includes the preparation of carrier and catalyst, the characterizationof carrier and catalyst and dynamic of the intrinsic.Crystal structure, preparation, content of V2O5and toxicity of SO2of compositeoxides carrier and catalyst tested by activity measurements and characterizationtechniques such as XRD, BET, NH3-TPD and so on. By thorough investigation, it isfound that a method is suitable for the preparation of SCR catalyst for coal-fired fluegas, kinetic parameter of selected SCR catalyst was obtained, and then a globalmathematical model was developed. Through the above research, mainly achieve thefollowing results:1) Two methods were used to prepare Al2O3-TiO2-ZrO2, the co-precipitationmethod was considered as the better method; on the other hand, the mechanical mixingmethod was not, because V2O5could not be evenly distributed.2) Ingredient optimization study of SCR catalyst by DeNOxactivity andcharacterization technologies shows5%V2O5/87%Al2O3-10%TiO2-3%ZrO2(w.t.%).3) In “clean gas” conditions, the catalytic performance was tested and concludedthat the catalyst has a higher NO removal efficiency(up to99%) and a low SO2oxidation efficiency under the condition that space velocity is10000h-1, NH3/NO ratiois1, and temperature range is from300to450℃. The influence of SO2on theperformance of catalyst was investigated under “dirty gas” condition. The NO reductionactivity did not decreased observably in the presence of low content of SO2(less than 2%) and the inhibition effect was reversible.4) Kinetic parameter of selected SCR catalyst was obtained, and then a globalmathematical model kinetics was developed, which can be used for the design andperformance of SCR catalyst.5) For the catalyst of5%V2O5/87%Al2O3-10%TiO2-3%ZrO2, the SCR reactionwas a first order reaction. The reaction was objected to Elay-Rideal mechanism—theNH3was first absorbed to the active site of the surface and reacted with the NO in thegas phase. The intrinsic activation energy of SCR reaction was172287.3J/mol, andpre-exponential factor was0.5086of cm3· g-1· s-1.Through the systematic research on composite oxides carrier, we got a suitableSCR catalyst formulation for coal-fired power plant, established a kinetic model, andlaid a good foundation for the development and operation of SCR catalyst.