商业V_2O_5-WO_3/TiO_2脱硝催化剂砷中毒机理  

The As Poisoning Mechanism over Commercial V_2O_5-WO_3/TiO_2 Catalyst

作　　者：周锦晖[1] 李国波 吴鹏 庄柯[1] 张亚平 沈凯 ZHOU Jln-hui;LI Guo-bo;WU Peng;ZHUANG Ke;ZHANG Ya-ping;SHEN Kai(State Power Environmental Protection Research Institute,Nanjing 210031,China;Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education,School of Energy and Environment,Southeast University,Nanjing 210096,China)

机构地区：[1]国电环境保护研究院,江苏南京210031 [2]东南大学能源与环境学院能源热转换及其过程测控教育部重点实验室,江苏南京210096

出　　处：《分子催化》2018年第5期444-453,共10页Journal of Molecular Catalysis(China)

基　　金：江苏省重点研发计划项目(BE2017716);环保公益性行业科研项目(2016YFC0208102);国家重点研发计划(2017YFB0603201)~~

摘　　要：采用浸渍法模拟商业V_2O_5-WO_3/TiO_2脱硝催化剂的砷中毒,并对不同As/V摩尔比中毒的催化剂进行脱硝实验测试,发现随着As中毒程度加深,催化剂的NOx转化率随之降低.当测试温度为400℃时,新鲜V_2O_5-WO_3/TiO_2催化剂NOx转化率有96.45%,而当As/V摩尔比到0.2的时候,As中毒催化剂的NOx转化率降低至不足67%.采用XRD、BET、SEM、in situ DRIFTS和H2-TPR等多种表征方法对As中毒前后催化剂的物性结构、表面物质的存在形式以及氧化还原性能的对比研究,结果显示As_2O_3堵塞催化剂微孔结构,导致催化剂表面微孔数量的减少,As_2O_5涂覆催化剂表面,进而阻碍了气相成分参与多相催化反应; As的引入使得表面形貌略有变差,并未导致催化剂晶型的变化,且As及其化合物在催化剂表面分散度较高. As会与催化剂表面的羟基作用形成As-OH,抑制催化剂酸性,尤其对Lewis酸的抑制效果明显; As中毒后的催化氧化还原能力增强.The arsenic poisoning of commercial V2O5-WO3/TiO2 denitration catalysts were simulated by impregnation method,and the denitration test for catalysts with different As/V molar ratios were carried out. It was found that the NOxconversion of the catalyst decreased with the deepening of As poisoning. When the test temperature is400 ℃,the denitration activity of the fresh V2O5-WO3/TiO2 catalyst is 96.45%,and when the As/V molar ratio is 0.2,the denitration activity of the As poisoning catalyst is reduced to less than 67%. XRD,BET,SEM,in situ DRIFTS and H2-TPR were used to compare the physical structure of the catalyst,the existence of surface substances and the redox properties of As2O3 before and after As poisoning. The results show that As2O3 blocks the microporous structure of the catalyst,resulting in a decrease in the number of micropores on the catalyst surface,As2O5 coats the surface of the catalyst,which hinders the gas phase component from participating in the heterogeneous catalytic reaction; the introduction of As makes the surface morphology slightly deteriorate,does not lead to the change of the crystal form of the catalyst,and As and its compounds The dispersion on the surface of the catalyst is high. As will react with the hydroxyl group on the surface of the catalyst to form As-OH,which inhibits the acidity of the catalyst,especially the inhibitory effect on Lewis acid; the catalytic redox ability after As poisoning is enhanced.

关 键 词：选择性催化还原 脱硝 催化剂 失活 机理 

分 类 号：O643.32[理学—物理化学]