V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for N...V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.展开更多
The structure and catalytic desulfurization characteristics of CeO2-TiO2 mixed oxides were investigated by means ofX-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and catalytic activity tests. Acco...The structure and catalytic desulfurization characteristics of CeO2-TiO2 mixed oxides were investigated by means ofX-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and catalytic activity tests. According to the results, a CeO2-TiO2solid solution is formed when the mole ratio of cerium to titanium n（Ce）：n（Ti） is 5：5 or greater, and the most suitable n（Ce）：n（Ti） isdetermined as 7：3, over which the conversion rate of SO2 and the yield of sulfur at 500℃ reach 93% and 99%, respectively.According to the activity testing curve, Ce0.7Ti0.3O2 （n（Ce）：n（Ti）=7：3） without any pretreatment can be gradually activated by reagentgas after about 10 min, and reaches a steady activation status 60 min later. The XPS results of Ce0.7Ti0.3O2 after different time ofSO2＋CO reaction show that CeO2 is the active component that offers the redox couple Ce4＋/Ce3＋ and the labile oxygen vacancies, andTiO2 only functions as a catalyst structure stabilizer during the catalytic reaction process. After 48 h of catalytic reaction at 500℃,Ce0.7Ti0.3O2 still maintains a stable structure without being vulcanized, demonstrating its good anti-sulfur poisoning performance.展开更多
基金supported by the National Natural Science Foundation of China (51372137)the National High Technology Research and Development Program of China (863 Program,2015AA034603)~~
文摘V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.
文摘The structure and catalytic desulfurization characteristics of CeO2-TiO2 mixed oxides were investigated by means ofX-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and catalytic activity tests. According to the results, a CeO2-TiO2solid solution is formed when the mole ratio of cerium to titanium n（Ce）：n（Ti） is 5：5 or greater, and the most suitable n（Ce）：n（Ti） isdetermined as 7：3, over which the conversion rate of SO2 and the yield of sulfur at 500℃ reach 93% and 99%, respectively.According to the activity testing curve, Ce0.7Ti0.3O2 （n（Ce）：n（Ti）=7：3） without any pretreatment can be gradually activated by reagentgas after about 10 min, and reaches a steady activation status 60 min later. The XPS results of Ce0.7Ti0.3O2 after different time ofSO2＋CO reaction show that CeO2 is the active component that offers the redox couple Ce4＋/Ce3＋ and the labile oxygen vacancies, andTiO2 only functions as a catalyst structure stabilizer during the catalytic reaction process. After 48 h of catalytic reaction at 500℃,Ce0.7Ti0.3O2 still maintains a stable structure without being vulcanized, demonstrating its good anti-sulfur poisoning performance.
