The CeO2‐TiO2(CeTi)and CeO2/WO3‐TiO2(CeWTi)catalysts were prepared by a sol‐gel precipitation method and their NH3‐NO/NO2 selective catalytic reduction(SCR)performance was studied.N2O formation and effect of oxyge...The CeO2‐TiO2(CeTi)and CeO2/WO3‐TiO2(CeWTi)catalysts were prepared by a sol‐gel precipitation method and their NH3‐NO/NO2 selective catalytic reduction(SCR)performance was studied.N2O formation and effect of oxygen concentration on SCR performance over CeWTi catalyst were also investigated while varying the NO2/NOx ratio.Results indicate that fast SCR behavior of CeWTi catalyst has the best NH3‐NO/NO2 SCR performance due to the catalyst reoxidation rate by NO2 higher than by O2.Compared with CeTi catalyst,CeWTi catalyst exhibits higher de‐NOx performance under NH3‐NO/NO2 SCR conditions.As the CeTi and CeWTi catalysts exhibit similar redox property,addition of WO3 provides more acid sites which accelerate the reaction between NH4NO3 and NO to get a superior low‐temperature activity.Amount of N2O formation shows a peak at 250 oC mainly derived from NH4NO3 decomposition.展开更多
The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition beha...The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.展开更多
An effective method for the regeneration of thermally deactivated commercial monolith SCR catalysts was investigated. Two types of regenerated solutions, namely NH4C1 （l mol/L） and dilute H2SO4 （0.5 tool/L）, were ...An effective method for the regeneration of thermally deactivated commercial monolith SCR catalysts was investigated. Two types of regenerated solutions, namely NH4C1 （l mol/L） and dilute H2SO4 （0.5 tool/L）, were employed to treat the used catalyst. The effects of temperature and the regeneration process on the structural and textural properties of the catalysts were determined by X-ray diffraction, scanning electron microscopy, N2 adsorption/desorption, elemental analysis and Fourier transform infrared spectroscopy. The results suggest that the anatase phase of the used catalyst is maintained after exposure to high temperatures. Some of the catalytic activity was restored after regeneration. The catalyst regenerated by aqueous NH4C1 had a higher activity than that of the catalyst treated by dilute H2SO4. The main reason is that the NH3 generated from the decomposition of NH4C1 at high temperatures can be adsorbed onto the catalyst which promotes the reaction. The aggregated V205 were partially re-dispersed during the regeneration process, and the intrinsic oxidation of ammonia with high concentrations of O2 is a factorthat suppresses the catalytic activity.展开更多
基金supported by the National Natural Science Foundation of China(51775296,51375253)~~
文摘The CeO2‐TiO2(CeTi)and CeO2/WO3‐TiO2(CeWTi)catalysts were prepared by a sol‐gel precipitation method and their NH3‐NO/NO2 selective catalytic reduction(SCR)performance was studied.N2O formation and effect of oxygen concentration on SCR performance over CeWTi catalyst were also investigated while varying the NO2/NOx ratio.Results indicate that fast SCR behavior of CeWTi catalyst has the best NH3‐NO/NO2 SCR performance due to the catalyst reoxidation rate by NO2 higher than by O2.Compared with CeTi catalyst,CeWTi catalyst exhibits higher de‐NOx performance under NH3‐NO/NO2 SCR conditions.As the CeTi and CeWTi catalysts exhibit similar redox property,addition of WO3 provides more acid sites which accelerate the reaction between NH4NO3 and NO to get a superior low‐temperature activity.Amount of N2O formation shows a peak at 250 oC mainly derived from NH4NO3 decomposition.
基金supported by the National Natural Science Foundation of China(No.51576039)
文摘The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.
文摘An effective method for the regeneration of thermally deactivated commercial monolith SCR catalysts was investigated. Two types of regenerated solutions, namely NH4C1 （l mol/L） and dilute H2SO4 （0.5 tool/L）, were employed to treat the used catalyst. The effects of temperature and the regeneration process on the structural and textural properties of the catalysts were determined by X-ray diffraction, scanning electron microscopy, N2 adsorption/desorption, elemental analysis and Fourier transform infrared spectroscopy. The results suggest that the anatase phase of the used catalyst is maintained after exposure to high temperatures. Some of the catalytic activity was restored after regeneration. The catalyst regenerated by aqueous NH4C1 had a higher activity than that of the catalyst treated by dilute H2SO4. The main reason is that the NH3 generated from the decomposition of NH4C1 at high temperatures can be adsorbed onto the catalyst which promotes the reaction. The aggregated V205 were partially re-dispersed during the regeneration process, and the intrinsic oxidation of ammonia with high concentrations of O2 is a factorthat suppresses the catalytic activity.
