Study On The Performance Of Cerium For V₂O₅-WO₃/TiO₂ Denitration Catalysts

In the direct or indirect combustion of coal in thenrmal power plants inChina,a large number of nitrogen oxides are emitted into the atmosphere,which will cause serious atmospheric environmental pollution.Selective Catalytic reduction(SCR)has been developed with the advantages of clean reaction product,simple structure,high catalytic reduction efficiency,stable operation and easy maintenance.In the process of SCR denitrification,catalyst is the key of this technology.V2O5-WO3/TiO2 and V2O5-WO3-CeO2/TiO2 catalysts were prepared by impregnation method.The optimum conditions for the preparation of V2 O5-WO3-CeO2/TiO2 were investigated by means of activity test,specific su rface area(BET),scanning electron microsccopy(SEM)and high power po lycrystalline X-ray diffraction(V2O5-WO3-CeO2/TiO2).The results show th at the catalyst has good denitrification activity when the calcination tempe rature is 500? and Ce02 is 10%.The results show that the specific surf ace area of V2O5-WO3-CeO2/TiO2 catalyst prepared by impregnation metho d is slightly reduced,the surface structure of the catalyst at several calcin ation temperatures has not been found obvious sintering phenomenon,and the crystal structure of anatase TiO2 has not changed.In order to investigate the influence of the preparation method on the catalyst,the V2O5-WO3-CeO2/TiO2 catalyst was prepared by distributed impregnation and one-step impregnation.The results were analyzed by scanning electron microscope(SEM)and laser Raman spectroscopy.The crystal structure of the catalysts prepared by the two methods has not changed much.Compared with the one-step impregnation method,the V2O5-WO3-CeO2/TiO2 catalysts prepared by the one-step impregnation method have been supported on the active components and calcined.The active component was more evenly dispersed on the surface of the carrier,which indicated that the catalyst prepared by step impregnation method was more favorable to the selective catalytic reduction reaction.When a small amount of SO2 was added into the gas,the activity of the V2O5-WO3-CeO2/TiO2 catalysts prepared by both methods had little change.Finally,in order to study the regeneration method of alkali metal poisoning catalyst,the V2O5-WO3-CeO2/TiO2 catalyst was simulated by K poisoning,and regenerated by water washing,washing acid pickling and washing tungsten,cerium and vanadium.The activity recovery of the regenerated catalyst was studied by means of activity measurement combined with specific surface area(BET),scanning electron microscopy(SEM),high power polycrystalline X-ray diffraction(XRD)and laser Raman spectroscopy.The results showed that the concentration of alkali ions in alkali metal solution had a great influence on the denitrification activity of the catalyst,and the regeneration method had different effects on the V2O5-WO3-CeO2/TiO2 catalyst caused by potassium poisoning during the regeneration experiment.However,the regeneration method of washing vanadium with pickling acid made the recovery of catalyst activity the most obvious,and the activity of the catalyst after poisoning was similar to that before poisoning,and the recovery of activity at low temperature was also better.