The Effect Of Alkali Metal On De-Nox Catalyst And Its Intrinsic Kinetic Research

Air pollution in our country is mainly coal-smoke pollution, which is caused by large amounts of sulfur dioxide and nitrogen oxides in the tail gas of coal burning power plant. Ammonia selective catalytic reduction (SCR) technique is very effective in De-NOx. And the key of this method is to develop appropriate SCR catalysts. V-W/TiO2catalyst has been widely used because of its excellent De-NOx performance, but the effect of the catalyst under the exhaust smoke temperature (413K-493K) was not that good. V2O5/AC catalyst has the good performances of both traditional vanadium catalyst and the activated carbon, which makes the catalyst have good catalytic activity under the exhaust temperature. The activity of the catalyst could be decreased for the reason of the alkaline dust when deal with real smoke. In order to achieve industrial application, the influence of the alkali metals on V2O5/AC catalyst has been investigated. Besides, the3D mathematical model of the reactor has been explored. The conclusions are as follows:1. The V2O5/AC catalyst was prepared by equivalent-volume impregnation method, using the grinded honeycomb active carbon granule as the carrier and the V2O5as the active component. Then K2SO4was loaded onto the V2O5/AC catalyst with different capacities. As a result, K0.5-V2/AC、 K1-V2/AC、K2-V2/AC catalyst was made. The BET and XPS tests of the active carbon granule and Kx-V2/AC catalyst were carried out. The BET result showed that K2SO4can block the pores in the catalyst while the XPS result told that the surface of the catalyst contained SO42+after pre-sulfide.2. The experimental condition of the intrinsic kinetic after pre-sulfide and the elimination of inside diffusion and outside diffusion:catalyst:0.35g, particle size:0.2-0.3mm, the reaction temperature:413-493K, total gas flow:400ml-min-1, the ratio of NO-to-NH3:0.81-1.31。3. Five kinds of dynamics models were choosing. And according to the experimental data and the expressions of the intrinsic kinetics model and the fixed bed integral reactor, all the parameters in the model were solved. The results of verified Eley-Rideal model and power series model were much closer to the experimental result, but the power series models can not reflect the phenomenon of the surface of the catalyst, therefore we choose Eley-Rideal model to explain the alkali metal effects on catalyst. By solving Eley-Rideal model, it can be found that the activation energy Ea increased gradually with the increase of K2SO4load, which meant that the activity of the V2O5/AC catalyst was affected by K2SO4through the increasing of the reaction activation energy activity.4. The mesh of the reactor and the structured catalyst were loaded into the FLUENT software and was simulated by four kinds of model respectively After verification, the Eley-Rideal model had good coincide with the experimental data.