VOx-MnOx/TiO2催化脱除氮氧化物与二英研究

Synergistic removal of nitrogen oxides and dioxins by VOx-MnOx/TiO2

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.

Dioxins will reduce human immunity and affect human and neurodevelopment;nitrogen oxides will cause serious damage to various organs and blood tissues of the human body,and will destroy the ozone layer and accelerate the formation of acid rain.Commercial vanadium-titanium catalyst can remove nitrogen oxides and catalyze the decomposition of dioxins(O-dichlorobenzene as a simulant).The dioxin activity temperature range is 200~300℃,and the SCR activity temperature is 300~400℃.The synergistic removal of nitrogen oxides and dioxins over the catalysts,such as VOx/TiO2,MnOx/TiO2 and VOx-MnOx/TiO2,were investigated at 200~300℃.The results showed that the addition of MnOx promoted the shift of active temperature window from 300~400℃ to 200~300℃ for VOx/TiO2 catalyst.The optimum VOx-MnOx/TiO2 catalyst exhibited the best catalytic performance at 250℃ when the molar ratio of MnO2 and V2O5 was 3∶1.The NO and o-dichlorobenzene efficiencies were 92.0% and 89.0%,respectively.In-situ infrared diffuse reflectance spectroscopy study showed that the SCR reaction on the surface of 1V3M/T catalyst followed the L-H mechanism at 250℃,and—NH2,Nx Hy Oz,monodentate nitrite and bidentate nitrate are the main reaction intermediates.