MnO2的晶相结构和表面性质对低温NH3-SCR反应的影响

采用水热法合成了两种具有相同形貌但是不同物相结构的MnO2纳米棒，分别为隧道状和层状结构。考察其低温NH。选择性催化还原NOx（NH3-SCR）的性能．结果表明MnO2纳米棒的比表面积不是影响活性的主要因素，催化剂的晶相结构和表面性质对催化活性有很大影响，隧道状a-MnO2纳米棒的低温NH3-SCR活性明显高于层状5-MnO2纳米棒．结构分析和NH。程序升温脱附（NH3-TPD）实验表明，a-MnO2纳米棒的暴露晶面（110）面存在大量的配位不饱和Mn离子，形成较多的Lewis酸性位点，而且a-MnO2较弱的Mn—O键和隧道结构都有利于NH。的吸附：而δ-MnO2纳米棒的暴露晶面（001）面上...

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Bibliographic Details
Published in物理化学学报 Vol. 28; no. 7; pp. 1771 - 1776
Main Author 戴韵 李俊华 彭悦 唐幸福
Format Journal Article
LanguageChinese
Published 清华大学环境学院,环境模拟与污染控制国家重点联合实验室,北京100084%复旦大学环境科学与工程系,上海,200433 2012
Subjects
a-MnO2
NH3-选择性催化还原NOx
δ-MnO2
低温
晶相结构
表面性质
低温
α-MnO2
晶相结构
NH3-选择性催化还原NOx
Low-temperature
Surface property
Selective catalytic reduction of NOx with NH3
δ-MnO2
表面性质
Crystal structure
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ISSN1000-6818
DOI10.3866/PKU.WHXB201204175

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Summary:采用水热法合成了两种具有相同形貌但是不同物相结构的MnO2纳米棒，分别为隧道状和层状结构。考察其低温NH。选择性催化还原NOx（NH3-SCR）的性能．结果表明MnO2纳米棒的比表面积不是影响活性的主要因素，催化剂的晶相结构和表面性质对催化活性有很大影响，隧道状a-MnO2纳米棒的低温NH3-SCR活性明显高于层状5-MnO2纳米棒．结构分析和NH。程序升温脱附（NH3-TPD）实验表明，a-MnO2纳米棒的暴露晶面（110）面存在大量的配位不饱和Mn离子，形成较多的Lewis酸性位点，而且a-MnO2较弱的Mn—O键和隧道结构都有利于NH。的吸附：而δ-MnO2纳米棒的暴露晶面（001）面上的Mn离子已达到配位饱和，所以其表面Lewis酸性位点较少．X射线光电子能谱（XPS）和热重（TG）分析表明a-MnO2纳米棒的表面更有利于NH3和NOX的活化．具有有利于吸附NH3和活化NH3和N0x的表面性质和晶型结构，是a-MnO：纳米棒活性高的主要原因．
Bibliography:11-1892/06
DAI Yun, LI Jun-Hua, PENG Yue,TANG Xing-Fu （1.State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beo＇ing 100084, P. R. China; 2.Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, P. R. China）
Two manganese oxides with the same nanorod-shaped morphology but different crystal structures, tunnel and layer structures, were synthesized and investigated for selective catalytic reduction of NOx with NH3 （NH3-SCR） at low temperature. Tunneled e-MnO2 had much higher catalytic activity than layered δ-MnO2 under the same reaction conditions. Experiment results revealed that the surface area was not the main factor to affect the NH3-SCR activities over the MnO2 nanorods and that the activities were structure sensitive. Structure analysis and temperature-programmed desorption experiments of NH3 （NH~-TPD） suggested that the exposed （110） plane of e-MnO2 had many Mn cations in coordinatively unsaturated environ
ISSN:1000-6818
DOI:10.3866/PKU.WHXB201204175