Research On The Performance Of NH₃-SCR Catalyst At Low Temperature

On the basis of laboratory research,the V₂O₅-WO₃/TiO₂ catalyst was systematically investigated.A series of catalysts were prepared by TiO₂ with different specific area,pore volume and particle size.The activity of the catalyst was tested.The results showed that the contribution of the specific surface area and pore volume to the catalyst activity were the greatest in the physical parameters of TiO₂.The effects of reaction conditions?NO_x inlet concentration,oxygen content,NH₃/NO_x,GHSV,SO₂ and H₂O?on the catalyst were investigated,and the optimum reaction conditions were determined.By means of the combination of de-nitration catalyst and NO oxidation catalyst,the results showed that the compact SCR could be improved the efficiency of standard SCR at high GHSV as to save space on a particular device,which may provide a solution for the space limitation on the mobile source,such as a vessel.The X-V₂O₅-WO₃/TiO₂ catalyst was studied and the results showed that the activity at low temperature could be promoted by addition of X.The activity could be achieved 90%at 160?.X could improve the sulfur resistance of the catalyst by weakening the interaction between the catalyst and ammonium sulfate.The efficiency could be maintained above 85%for 800 min at 175?when the 100ppmSO₂ and10%H₂O were introduced.Its activity and sulfur tolerance at low temperature are better than other catalysts in this paper,and the preparation method is simple and easy to operate,which lays a foundation for future industrial applications.The modification of the V₂O₅-WO₃/TiO₂ carrier was investigated and the results showed that the catalysts was prepared by the mixture of zeolite and titanium dioxide exhibited low activity and sulfur resistance due to its small specific surface area and the loss of active components.The catalysts was prepared by the mixture of Al₂O₃ and titanium dioxide showed low activity and sulfur resistance at 120-250?and high efficiency at high temperature?360-400??.The analysis results showed that the doping of alumina weakens the effect of V₂O₅ and TiO₂,which lead to the decrease of efficiency,while the larger specific surface area of alumina caused the accumulation of more ammonium sulfate,which accelerated the deactivation of the catalyst.The V₂O₅-Y/TiO₂ catalyst was studied and the results showed that the addition of antimony could improved the redox ability of the catalyst and then advanced the low-temperature activity.The activity of catalyst could be reached 90%at 170?.The influences of Y loading and calcination temperature on the performance of catalyst were also investigated.The V₂O₅-Y/TiO₂ catalyst with 11%Y and calcined at 500?exhibited the best activity.It also showed a good sulfur resistance which the efficiency could be maintained above 80%for 100h at 200?when the 300ppmSO₂and 10%H₂O were existed.The formation of ammonium sulfate and Y sulfated were the main reason for the deactivation of the catalyst.The ammonium sulfate on the surface has disappeared after calcination at 500?for 4h,but it could not reach the original level.It was inferred that the mechanism of sulfur resistance of antimony was reduced the accumulation of ammonium sulfate on the surface of catalyst,and then delay the deactivation of catalyst.