Impregnation Regeneration And SO₂Oxidation Control Of The SCR Denitration Catalysts

The promulgation of the new "thermal power plant air pollutant emission standards"means the denitrification of flue gas will become more and more important in theenvironmental engineering of thermal power plant. Denitration technology is Merrently themost widely used method for Selective Catalytic Reduction （SCR）. As the core part of theSCR， the catalysts are not only so expensive that they account for approximately40%of theover all cost，but also need to be replaced about every three years. However，as the growingof the installed capacity of the denitration equipment it is expected that there will be a stable88，000m3/a deactivated catalyst in2018under the "2+1" setup mode. The regeneration of theSCR catalyst can also avoid serious waste of resources and secondary pollution， and makesignificant economic benefits. Therefore， regeneration of the catalysts is the only way todevelop SCR denitrification industry.This paper studied the adsorption and impregnating behavior of the active component Vin the SCR catalyst during regeneration. It used electric double layer theory to explain theadsorption behavior of V on catalysts. Zeta potential measurement indicated that the catalystscarried a large amount of negative charges， so it can significantly adsorb VO2+and reachthemaximum load. The innovation of this paper is the application of electric double layertheory to explain and analysis the adsorption behavior of V on the SCR catalyst duringregeneration.Since that metal-doping can lower the electron density on the bridging V-O-M oxygenand weaken its basicity， thus reduce its SO₂adsorption and inhibit SO₂oxidation. Me wasused in this paper to dope SCR catalyst. It showed that when the Me doping amount was0.6%，the SO₂/SO₃conversion rate of SCR catalyst was0.68%， less than0.73%， which is the ratebefore regeneration， and NO conversion was94.47%， which decreased only4%comparedto the catalysts without Me. The reason for the dropping of SO₂oxidation rate is that Medoping can decrease V5+and increase V4+content thus inhibit the transformation of O-atominthe crystal lattice.The calculation of dmol3module also showed that the charges of bridgingV-O-M oxygen changed from positive to negative after Me doping， and was less basicV-O-M oxygen. As a result， SO₂oxidation rate was reduced. The results of the third party institution showed that the performance of the catalystregeneration method in this paper was good when applied in practical power plants. SO₂/SO₃conversion rate and other performance are within national standards.