MnOx_MWCNTs低温氨选择性催化还原NOx硫中毒机理

MnO x /MWCNTs 低温氨选择性催化还原NO x 硫中毒机理

罗红成1

黄碧纯1,2,*

付名利1,2

吴军良1,2叶代启1,2

(1华南理工大学环境科学与工程学院,广州510006;2

华南理工大学工业聚集区污染控制与

生态修复教育部重点实验室,广州510006)

摘要:

以经过浓硝酸和等离子体放电预处理后的多壁碳纳米管(MWCNTs)为载体,锰氧化物(MnO x )为活性组

分,采用等体积浸渍法制备MnO x /MWCNTs 催化剂.利用热重分析(TGA)、扫描电子显微镜(SEM)、X 射线衍射(XRD)、X 射线光电子能谱(XPS)、程序升温还原/脱附(TPR/TPD)以及傅里叶变换红外(FTIR)光谱对催化剂进行表征,探讨SO 2对催化剂低温氨选择性催化还原(SCR)NO x 活性的影响及SO 2中毒机理.结果表明,低温下SO 2对MnO x /MWCNTs 催化剂活性有明显毒化作用.反应温度越高,SO 2浓度越大,催化剂SCR 活性下降越快.活性中心Mn 原子硫酸化是催化剂失活的主要原因.另外,催化剂表面生成硫酸铵盐以及SO 2对NO 吸附的抑制作用也一定程度上造成了催化剂的失活.关键词:

多壁碳纳米管;选择性催化还原;二氧化硫;中毒机理

中图分类号:

O643

SO 2Deactivation Mechanism of MnO x /MWCNTs Catalyst for

Low-Temperature Selective Catalytic Reduction of NO x by Ammonia

LUO Hong-Cheng 1

HUANG Bi-Chun 1,2,*

FU Ming-Li 1,2

WU Jun-Liang 1,2

YE Dai-Qi 1,2

(1College of Environmental Science and Engineering,South China University of Technology,Guangzhou 510006,P .R.China ;

2

Key Laboratory of the Ministry of Education for Pollution Control and Ecosystem Restoration in Industry Clusters,

South China University of Technology,Guangzhou 510006,P .R.China )

Abstract:Manganese oxides supported on multi-walled carbon nanotubes (MnO x /MWCNTs)catalysts were prepared by pore volume impregnation using MWCNTs as the catalyst support which was pretreated by concentrated nitric acid and oxygen dielectric barrier discharge plasma.The catalysts were characterized by thermogravimetric analysis (TGA),scanning electron microscopy (SEM),X-ray powder diffraction (XRD),X-ray photoelectron spectroscopy (XPS),temperature-programmed reduction/desorption (TPR/TPD),and Fourier transform infrared (FTIR)spectroscopy.The effect of SO 2on the activity of the catalysts for low-temperature selective catalytic reduction (SCR)of NO x by ammonia and the SO 2poisoning mechanism were investigated.The results showed that SO 2had an obvious poisoning effect on the SCR activity of MnO x /MWCNTs at low temperature.The activity decreased more rapidly as reaction temperature and SO 2concentration increased.The observed deactivation was attributed to the sulfation of the active center atoms.Formation of ammonium sulfate on the catalyst surface and the inhibiting effect of SO 2on NO adsorption also resulted in the deactivation of the catalysts to some extent.Key Words:

Multi-walled carbon nanotubes;Selective catalytic reduction;Sulfur dioxide;Poisoning

mechanism

[Article]

doi:10.3866/PKU.WHXB201207062

物理化学学报(Wuli Huaxue Xuebao )

Acta Phys.-Chim.Sin .2012,28(9),2175-2182

September Received:June 18,2012;Revised:July 6,2012;Published on Web:July 6,2012.∗

Corresponding author.Email:cebhuang@;Tel:+86-20-39380519.

The project was supported by the National Natural Science Foundation of China (209077034).国家自然科学基金(209077034)资助项目

ⒸEditorial office of Acta Physico-Chimica Sinica

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