Fe改性分子筛催化剂CH_(4)选择性催化还原N_(2)O  

CH_(4)selective catalytic reduction of N_(2)O by Fe-modified molecular sieve catalysts

作　　者：温鹏 刘宁[1] 陈标华 代成娜 WEN Peng;LIU Ning;CHEN Biaohua;DAI Chengna(College of Environmental Science and Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学环境科学与工程学院,北京100124

出　　处：《化工环保》2024年第3期398-404,共7页Environmental Protection of Chemical Industry

基　　金：国家自然科学基金项目(22178011,22176006)。

摘　　要：针对N_(2)O的CH_(4)选择性催化还原(CH_(4)-SCR),采用浸渍法制备了系列Fe改性分子筛(BEA、ZSM-5、SSZ-13)催化剂。实验结果表明:2%Fe-BEA(负载量2%(w))具有较高的催化活性,在进气(N_(2)O 40%(φ,下同),CH_(4)10%,N250%)总流量为50 mL/min、反应器气时空速为12000 h^(–1)的条件下,250℃时的N_(2)O转化率达99.5%,CH_(4)转化率达94.6%;反应器连续运行20 h,N_(2)O转化率基本保持不变,CH_(4)转化率仅略有下降。表征结果显示,2%Fe-BEA较高的催化活性与其易形成大量离子态Fe^(3+)活性物种密切相关,而2%Fe-SSZ-13更易形成大量FeOx物种,故在3种分子筛催化剂中催化活性最低。2%Fe-BEA上N_(2)O的CH_(4)-SCR遵循自由基反应机理,形成羟基自由基和甲氧基自由基,并可经进一步氧化,通过甲酸盐路径生成CO_(2)和H2O。A series of Fe-modified molecular sieve(BEA,ZSM-5,and SSZ-13)catalysts for CH_(4)selective catalytic reduction(CH_(4)-SCR)of N_(2)O were prepared by immersion method.The experimental results show that 2%Fe-BEA(load of 2%(w))has high catalytic activity.Under the conditions of inlet air flow(N_(2)O of 40%(φ,the same below),CH_(4)of 10%,and N2 of 50%)of 50 mL/min and reactor air speed of 12000 h^(–1),the conversion rate of N_(2)O can reach 99.5%at 250℃.The conversion rate of CH_(4)is 94.6%.When the reactor runs continuously for 20 h,the conversion rate of N_(2)O remainsbasically unchanged,and that of CH_(4)decreases slightly.The results show that the higher catalytic activity of 2%Fe-BEA is closely related to the formation of a large number of ionic Fe^(3+)active species,while 2%Fe-SSZ-13 is more likely to form a large number of FeOx species,so its catalytic activity is the lowest among the three molecular sieve catalysts.The CH_(4)-SCR of N_(2)O on 2%Fe-BEA follows the radical reaction mechanism to form hydroxyl radicals and methoxyl radicals,which can be further oxidized to form CO_(2)and H2O through the formate path.

关 键 词：N_(2)O CH_(4)选择性催化还原(CH_(4)-SCR) Fe-BEA分子筛 反应机理 

分 类 号：X701[环境科学与工程—环境工程]