二噁英会降低人类的免疫力,影响人体和神经发育;氮氧化物则会对人体的各项脏器和血液组织有严重危害,还会破坏臭氧层,加速酸雨的形成.商业钒钛催化剂既能脱除氮氧化物又能催化分解二噁英(邻二氯苯作为模拟物),二噁英活性温度区为200~300...二噁英会降低人类的免疫力,影响人体和神经发育;氮氧化物则会对人体的各项脏器和血液组织有严重危害,还会破坏臭氧层,加速酸雨的形成.商业钒钛催化剂既能脱除氮氧化物又能催化分解二噁英(邻二氯苯作为模拟物),二噁英活性温度区为200~300℃,而脱硝活性温度为300~400℃.研究了VOx/TiO2、MnOx/TiO2以及VOx-MnOx/TiO2等催化剂在200~300℃脱硝、脱除二噁英的情况.结果表明,在VOx/TiO2催化剂中掺入MnOx促进脱硝活性温度区间由300~400℃往200~300℃偏移,当MnOx和VOx摩尔比为3∶1时,催化剂在250℃脱硝和脱除二噁英的效果最好,催化NO和邻二氯苯效率分别为92.0%和89.0%.原位红外漫反射光谱研究表明,1V3M/T催化剂表面的脱硝反应在250℃遵循L-H机理,—NH2、Nx Hy Oz、单齿亚硝酸盐和二齿硝酸盐是主要的反应中间体.展开更多
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
文摘二噁英会降低人类的免疫力,影响人体和神经发育;氮氧化物则会对人体的各项脏器和血液组织有严重危害,还会破坏臭氧层,加速酸雨的形成.商业钒钛催化剂既能脱除氮氧化物又能催化分解二噁英(邻二氯苯作为模拟物),二噁英活性温度区为200~300℃,而脱硝活性温度为300~400℃.研究了VOx/TiO2、MnOx/TiO2以及VOx-MnOx/TiO2等催化剂在200~300℃脱硝、脱除二噁英的情况.结果表明,在VOx/TiO2催化剂中掺入MnOx促进脱硝活性温度区间由300~400℃往200~300℃偏移,当MnOx和VOx摩尔比为3∶1时,催化剂在250℃脱硝和脱除二噁英的效果最好,催化NO和邻二氯苯效率分别为92.0%和89.0%.原位红外漫反射光谱研究表明,1V3M/T催化剂表面的脱硝反应在250℃遵循L-H机理,—NH2、Nx Hy Oz、单齿亚硝酸盐和二齿硝酸盐是主要的反应中间体.
基金Supported by Fundamental Research Funds for Central Universities(HEUCF201403002)Advanced Technique Project Funds of the Manufacture and Information Ministry
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.
