Sb改性钒钛SCR脱硝催化剂抗CO中毒性能  

Mechanism of anti-CO poisoning of Sb-modified vanadium-titanium SCR denitrification catalysts

作　　者：刘法志 张鹏威 刘涛[2] 谢玉仙 何建乐 苏胜[2] 徐俊[2] 向军[2] LIU Fazhi;ZHANG Pengwei;LIU Tao;XIE Yuxian;HE Jianle;SU Sheng;XU Jun;XIANG Jun(China Huadian Electric Power Research Institute Co.,Ltd.,Hangzhou 310029,Zhejiang,China;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,Hubei,China)

机构地区：[1]华电电力科学研究院有限公司,浙江杭州310029 [2]华中科技大学煤燃烧与低碳利用全国重点实验室,湖北武汉430074

出　　处：《化工进展》2025年第2期1129-1137,共9页Chemical Industry and Engineering Progress

基　　金：华电集团揭榜挂帅项目(CHDKJ22-01-108);国家自然科学基金(U20A20302,52106149)。

摘　　要：目前,在燃煤电厂灵活调峰过程中会出现烟气中CO浓度排放过高问题,这会对脱硝系统中钒钛催化剂氨气选择性催化还原(NH_(3)-SCR)脱硝性能造成影响。本文采用超声浸渍法制备钒钛催化剂及Sb改性钒钛催化剂,研究了CO对钒钛催化剂NH_(3)-SCR脱硝性能的影响,同时探究了Sb改性对提高钒钛催化剂抗CO中毒机理,通过N2吸脱附、X射线衍射(XRD)、X射线光电子能谱(XPS)及原位红外漫反射(in-situ DRIFT)等方法对催化剂样品进行了表征分析。结果表明:CO的存在会抑制2.5V/Ti催化剂的NH_(3)-SCR脱硝活性,Sb改性可以提高催化剂的NH_(3)-SCR脱硝性能并减弱CO对催化剂脱硝活性的抑制作用。一方面,CO通入后使得2.5V/Ti催化剂表面V^(5+)和O_(α)含量减少,抑制了催化剂表面NH_(3)-SCR反应进行;另一方面,CO会在2.5V/Ti催化剂表面与NH_(3)和NO产生竞争吸附,抑制催化剂表面NH_(3)的吸附以及NH_(2)中间产物的形成,减少表面活性双齿型硝酸盐和桥式硝酸盐的生成并且减缓双齿型硝酸盐和NH_(3)以及NH_(3)(L)和NO+O_(2)的反应,从而抑制了催化剂NH_(3)-SCR脱硝活性。Sb改性显著增加了催化剂表面O_(α)的含量,并通过2V^(4+)+Sb^(5+)■2V^(5+)+Sb^(3+)这一氧化还原循环减弱了CO对V-3Sb/Ti催化剂表面V^(5+)含量的影响。此外,Sb改性还促进了催化剂表面SCR反应活性物种的生成,提高了CO存在时V-3Sb/Ti催化剂表面NH_(3)(L)的反应性,因此V-3Sb/Ti催化剂表现出优异的NH_(3)-SCR性能和更好的抗CO中毒特性。At present,the problem of high CO concentration in the flue gas emission occurs during the flexible peaking process of coal-fired power plants,which affects the denitrification performance of the vanadium-titanium catalyst in the denitrification system.In this study,vanadium-titanium catalysts and Sb-modified vanadium-titanium catalysts were prepared by ultrasonic impregnation,and the effect of CO on the NH_(3)-SCR denitrification performance of vanadium-titanium catalysts was investigated,while the mechanism of Sb-modification in improving the anti-CO poisoning performance of vanadium-titanium catalysts was also explored.The catalyst samples were characterized and analyzed by N2 adsorption and desorption,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and in-situ infrared diffuse reflection(in-situ DRIFT).The results showed that the presence of CO deteriorated the NH_(3)-SCR denitrification performance of the 2.5V/Ti catalysts,while the Sb modification could improve it by weakening the inhibitory effect of CO.With the introduction of CO,the V^(5+)and O_(α)contents on the surface of 2.5V/Ti catalyst were decreased,which inhibited the NH_(3)-SCR reaction on the catalyst surface.CO would compete with NH_(3)and NO for adsorption on the surface of the 2.5V/Ti catalyst,thus inhibiting the adsorption of NH_(3)and the formation of NH_(2)intermediates.Meanwhile,because of the presence of CO,surface active bidentate and bridge nitrate production was limited and the reactions between bidentate nitrate and NH_(3)as well as NH_(3)(L)and NO+O_(2)were slowed down,which inhibited the NH_(3)-SCR denitrification performance of the 2.5V/Ti catalysts.The Sb modification significantly increased the O_(α)content on the catalyst surface and weakened the effect of CO on the V^(5+)content on the V-3Sb/Ti catalyst surface through a redox cycle of 2V^(4+)+Sb^(5+)■2V^(5+)+Sb^(3+).In addition,the Sb modification promoted the formation of SCR reactive species on the catalyst surface and improved the reactivity of NH_(3)(L)on

关 键 词：煤燃烧 烟道气 一氧化碳 选择性催化还原 催化剂 锑改性 

分 类 号：TH3[机械工程—机械制造及自动化]