Study On Performance And Regeneration Of V₂O₅-WO₃/TiO₂ SCR Denitrification Catalyst

Nitrogen oxides?NOx?from thermal power plant flue gas are the main pollutants to promote the formation of photochemical smog and acid rain,which caused great harm to human health and the environnment.Selective catalytic reduction?SCR?flue gas denitration technology research on domestic and foreign becomes more mature at present,has been regarded as the most efficient technology for abating NOX and widely used in thermal power industries.Because of a large proportion of catalysts in the total cost of the SCR system,the catalysts are the key for selective catalytic reduction.The V₂O₅-WO₃/TiO₂ and V₂O₅-WO₃/TiO₂?P25?catalysts were prepared by impregnation method,and the samples were characterized by field emission scanning of electron microscopy?FESEM?,energy dispersive spectrometer?EDS?,X-ray diffractometer?XRD?,thermal gravity analysis?TGA?and laser Raman spectroscopy.The effects of four parameters on NH3-SCR denitration performance were investigated,that were TiO2 crystal form,vanadium content,SO2 and activity test time.Results indicated that the catalyst prepared with anatase TiO2 support was more conducive to the occurrence of SCR reaction.In NH3-SCR experiments,the flue gas without SO2,V₂O₅-WO₃/TiO₂?P25?catalysts were not as active as V₂O₅-WO₃/TiO₂ catalysts,V2O5 loaded of V₂O₅-WO₃/TiO₂ at 3 wt.%has the best denitration performance.The activity of V2O5-W0O/TiO2?P25?has larger ascension instead with 0.08%SO2,denitration rate of V₂O₅-WO₃/TiO₂ could remain stable at around 94%at 300 ? within 48 hTo broaden the V2O5-VWO3/TiO2 temperature range,it was modified with doping SiO2.The V₂O₅-WO₃/TiO₂-SiO2 catalyst was prepared by impregnation method with TiO2-SiO2 carrier,which was prepared by sol-gel method,and the samples were characterized by low temperature N2 adsorption,FESEM,EDS,XRD,TGA and laser Raman spectroscopy.The influence of reaction temperature,SiO2 doped amount,calcination temperature,space velocity and activity test time were investigated on NH3-SCR denitration performance.Characterization results indicated that V₂O₅-WO₃/TiO₂-SiO2 was more conducive to the occurrence of SCR reaction.The NH3-SCR experiments found V₂O₅-WO₃/TiO₂-SiO2 optimal preparation conditions:TiO2/SiO2=2,calcination temperature was 400 ?.The space velocity made little effect on V₂O₅-WO₃/TiO₂-SiO2,when space velocity at 20000 h-1 and the reaction temperature was 300 ?,the denitration efficiency of catalyst could maintain at 99%within 48 h.In addition,for the study on anti-toxic and regeneration of V₂O₅-WO₃/TiO₂,the catalyst was impregnated with KNO3 solution at different concentrations forced poisoning deactivation,regeneration by water washing,acid washing,and then loding vanadium.And the poisoning and regeneration samples were characterized by FESEM,EDS,XRD and laser Raman spectroscopy.The influence of potassium concentration,regeneration methods and activity test time were investigated on the denitration performance.Characterization results showed the surface morphology and crystal form of potassium poisoning and regeneration catalysts changed little,but K can be removed by water washing,acid washing,and loding vanadium process.The NH3-SCR experiments found that higher potassium concentration,the stronger the catalyst poisoning.Regeneration method effect was water washing and acid washing and loding vanadium>water washing and acid washing>water washing,water washing and acid washing and loding vanadium method made poisoning catalyst recovery activity,and it can be maintained stable denitration performance at 350 ? within 48 h.