Preparation And Characterization Of Denitrafication Catalystic Carries From Metatitanic Acid

NOx is a major air pollutant,which is one of the most reasons to lead to the nitric acid rain and photochemical smog.Nowaday,the emission of NOx of China is more than 22 million tons per year,which exceeds that of U.S and makes China become the world’s largest country to emit NOx.Therefore,China had formulated the most stringent NOx emission standards in the world.To achieve the target of reduction of nitrogen oxides,strengthening the research on ammonia selective catalytic reduction(SCR)technology and theory,developing carriers with good performances and reducing the cost of catalysts of V2O5-WO3/TiO2 are becoming imminent.The ultrafine titanium dioxide and Ti-W composite powder are all prepared by thermal decomposition method with the metatitanic acid which is the intermediates of the production of titanium dioxide in sulfate process.Various influence factors for the performance of the powder were investigated in this reseach.Meanwhile,the powders were characterized by BET,XRD,XRF,SEM,particle size analyzer,etc.and compared with the commercial ultrafine titanium dioxide and Ti-W composite powder.Simultaneously,the V2O5-WO3/TiO2 catalysts were prepared with metatitanic acid through the methods of wet impregnation and thermal decomposition of solid material for selective catalytic reduction(SCR)of NOx with NH3.The catalysts were characterized by kinds of techniques.And the denitrafication performance of the catalysts was also studied.As the results showed when the slurry concentration was 15%and pH was 5.0 or did not adjust,sodium dodecyl sulfonate as dispersant and the addition was 0.4%of TiO2 by mass,the calcination temperature was increased from RT to 500 for 2h and then kept at 500℃ for 4 hours,35～40 g sample was milled for 12 minutes by Smasher,qualified ultrafine titanium dioxide powder and Ti-W composite powder,which have better performances than that of the commercial ones,can be obtained.Moreover,the results of De-NOx tests under the simulated flue gas demonstrated that V2O5(1.2%)-WO3(8.8%)/TiO2 catalysts possess high catalytic activity and broad activity temperature window,and the NO conversion reaches 98.77%.Considering the NH3 escape,equipment corrosion and environmental issues,it’s suitable to control the molar ratio of NH3/NO within 1.2.De-NOx catalytic reaction is more favorable at oxygen-rich conditions.