The Experiment Study And Numerical Simulation Of Multi-component Catalysts In The Selective Catalytic Reduction (SCR) Of Nitrogen Oxides

With Chinese economy developing rapidly since 1990's of the 20th century, the nitrogen oxide pollution had increased seriously. The controlling of the nitrogen oxide emission has already become an urgent task.The paper introduced the environmental protection trend of the electric power industry and presented some different methods of decreasing nitrogen oxide. In the dissertation,selective catalytic reduction (SCR) of NOX by ammonia was adopted. DeNOX performance of catalyst preparation was tested in a fixed-bed reactor. An experimental research was carried on making to give analysis of selective catalysts of V2 O5-WO(3MoO3,CeO2) over nano-meter anatase TiO2 which made by ourselves. The paper focused on how some operation parameters affect the conversion of NO, NO2 and N2 O, such as temperature, NH3/NO ratio, space velocity and catalytic component. The result indicated that the effect of DeNOx with MoO3 -V2 O5/TiO2 which was more remarkable than that with catalysts contained WO3 and CeO2,while its selectivity for N2 O was higher. As W/Mo mole equal to 1/2 in catalysts of WO3 -MO3-V2 O5 /TiO2, better effect of DeNOx was obtained. Compared with the experimental data, the applicable scope and conditions of the catalysts were summarized.Neglected the outer diffusion influence of catalysts, based on simple condition of reaction,the first class kinetics model adopted the mechanism of ER and analyzed the experiment data by regressive method, the latent activate energy of three catalysts were acquired. It also analyzed the activate energy of other reference literatures to make a comparison. The activate energy of 3%WO3 -6.7%MoO3 - V2O5 /TiO2 was smaller than the others, which shown that the reaction rate of 3%WO3 -6.7%MoO3 - V2O5 /TiO2 was quickly in the same temperature.Computational Fluid Dynamics (CFD) software-FLUENT was imported into numerical simulate of SCR reaction. The velocity distribution,pressure distribution and concentration distribution of four catalysts under different structures were simulated in a small reaction based on Fluent's physical,mathematic,chemical model and chemistry dynamics parameters acquired from experimental data. The paper also analyzed resistances and Arrhenius rate of different conditions. What's more, the efficiency of DeNOx in the SCR reactor of four kinds of catalysts were simulated. It's shown that external mass-transfer phenomena were not significance for the catalytic reduction of NO with NH3 and O2 in high space velocity, but pore diffusion is very important to the reaction.