Low-temperature catalytic degradation of the odorous pollutant hexanal by γ-MnOOH:The effect of Mn vacancies  

γ-MnOOH低温催化降解异味气体正己醛:锰缺陷的影响（英文）

作　　者：Shanhong Sui Pengyi Zhang Huiyu Zhang Ranran Cao 随山红;张彭义;张惠玉;曹冉冉(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;室内空气质量评价与控制北京市重点实验室,北京100084)

机构地区：[1]State Key Joint Laboratory of Environment Simulation and Pollution Control,School of Environment,Tsinghua University,Beijing 100084,China [2]Beijing Key Laboratory for Indoor Air Quality Evaluation and Control,Beijing 100084,China

出　　处：《Chinese Journal of Catalysis》2019年第10期1525-1533,共9页催化学报（英文）

基　　金：supported by National Natural Science Foundation of China (21677083);Suzhou-Tsinghua Innovation Guiding Program (2016SZ0104)~~

摘　　要：irritation to human beings.The removal of hexanal has rarely been investigated.In this study,we found that the amount of Mn vacancies inγ-MnOOH significantly affects its catalytic activity toward hexanal degradation and transformation into CO2.The as-synthesized Mn vacancy-richγ-MnOOH exhibited high efficiency toward hexanal removal,achieving 100%degradation of 15 ppm hexanal at 85℃ and complete transformation into CO2 at 160 ℃ under the gas hourly space velocity of 240 L/(g·h);its activity could be completely regenerated by in-situ heat treatment at 180°C.Moreover,it was found that the degradation of hexanal occurred in a stepwise manner,i.e.,losing one CH2 unit per step.Electron spinning resonance studies detected strong indicative signals for the presence of the superoxide anion radical(?O2^–)on Mn-vacancy-richγ-MnOOH,which may act as active oxygen species for the hexanal degradation.Understanding the role of Mn-vacancy and the mechanism of hexanal degradation byγ-MnOOH are essential for developing efficient oxide catalysts for volatile organic compounds besides hexanal.正己醛是室内常见的挥发性有机物,主要由板材类家具等释放,由于其嗅味阈值很低、检出率高,是引起室内异味的主要成分之一,目前对正己醛的催化去除研究很少.γ-MnOOH是常见的羟基锰氧化物,常作为合成其他锰氧化物的前驱体,在超级电容、离子电池、催化等领域有广泛的应用前景,但将其作为气相反应催化剂的研究较少,关于γ-MnOOH中锰缺陷含量对其催化性能的影响未有报道.本文通过两种水热反应体系制备了结晶性良好的γ-MnOOH催化剂,通过在高锰酸钾-乙二醇制备体系中添加一定量的硫酸制备了高锰缺陷含量的γ-MnOOH催化材料,通过正己醛的动态催化氧化反应体系对不同样品的催化性能进行了评价.结果表明,高锰缺陷含量的γ-MnOOH对正己醛具有很高的催化活性,85℃下可以将浓度为15ppm、相对湿度50%、质量空速(GHSV)为240L/(g·h)的正己醛完全去除,在160℃下可将正己醛完全转化为CO2.通过X射线衍射、扫描电镜、透射和高分辨透射电镜、N2吸附-脱附,拉曼光谱(Raman)、X射线光电子能谱(XPS)、氢气程序升温还原(H2-TPR)、氧气程序升温脱附(O2-TPD)和电子自旋共振谱(ESR)对材料的结构、形貌及物理化学性质等进行了表征,并通过热脱附-气相色谱/质谱联用(ATD-GC/MS)和原位红外光谱分别对正己醛催化氧化反应中的气相产物、催化剂表面的中间物种进行了鉴别.材料结构和形貌表征结果表明,高锰缺陷含量的γ-MnOOH结晶性相对较差,表面晶格条纹畸变及化学键无序性很大,锰的平均价态较高;H2-TPR和O2-TPD的测试结果表明,添加硫酸制备的催化剂起始还原温度低,还原过程连续性及晶格氧的迁移转化能力增强,表面吸附氧物种含量增大;ESR的测试结果也表明,该材料活化氧气产生超氧自由基(?O2^–)的能力更强,这些都有利于提高催化剂的催化活性.ATD-GC/MS的表征结果表明,当正己醛�

关 键 词：Γ-MNOOH Manganese vacancy Hexanal degradation Indoor air Catalysis 

分 类 号：O64[理学—物理化学]