作　　者： ; ; ; ; ; ; ;

机构地区： 华南理工大学环境科学与工程学院

出　　处： 《催化学报》 2011年第6期904-916,共13页

摘　　要： 采用浸渍法制备了Al2O3负载的5种过渡金属氧化物催化剂,考察了它们在常温下催化臭氧氧化甲苯的性能,并运用程序升温还原、程序升温氧化、N2吸附-脱附和X射线光电子能谱对催化剂进行了表征.结果表明,NiO/Al2O3,CoO/Al2O3和MnO2/Al2O3催化剂上活性氧中心数量较少,臭氧与甲苯转化率较高;而Fe2O3/Al2O3和CuO/Al2O3催化剂上则相反.催化降解臭氧效率较高的催化剂上甲苯转化率也较高,在本文实验条件下,CO2产率低于30%.当甲苯浓度为666mg/m3,O3浓度从193mg/m3提高至965mg/m3时,甲苯转化率从15.2%提高至46.7%,并且使反应后催化剂表面产物和晶格氧含量增加.原位漫反射红外光谱研究发现,反应过程中生成了含COO-,C=O和C-O官能团的物质,O3浓度的提高加速了COO-向C=O与C-O的转化,前者在573KO2气氛下几乎不发生反应,而后者在373K开始分解.基于此,提出了常温下臭氧催化氧化甲苯的反应机理. Five kinds of transition metal oxides supported on alumina and prepared by wetness impregnation were evaluated for the catalytic ozonation of toluene at room temperature and characterized by temperature-programmed reduction,temperature-programmed oxidation,N2 adsorption-desorption,and X-ray photoelectron spectroscopy.The catalysts with a lower reduction temperature and less H2 consumption showed a higher efficiency for ozone and toluene decomposition,such as NiO/Al2O3,CoO/Al2O3,and MnO2/Al2O3,while lower efficiency were observed on Fe2O3/Al2O3 and CuO/Al2O3.Toluene decomposition efficiency was obviously dependent on ozone.Because of the low ozone to toluene concentration ratio,a CO2 yield of less than 30% was obtained.At a toluene concentration of 666 mg/m3 and an ozone concentration between 193 and 965 mg/m3,toluene conversion was found to vary from 15.2% to 46.7%.Additionally,we observed an increase in oxidation products and lattice oxygen on the catalyst surface.A preliminary investigation into the reaction pathway was undertook by in situ diffuse reflectance Fourier transform infrared spectroscopy.With regards to the formation of COO-,C=O,and C-O groups the high ozone concentration accelerated the transformation from COO- to C=O and C-O.The substance containing COO-remained unchanged at 573 K,while the substances containing C=O and C-O underwent oxidation at higher than 373 K.A possible reaction pathway is proposed based on these findings.

关 键 词： 三氧化二铝 过渡金属氧化物 甲苯 臭氧 室温 原位漫反射红外光谱

领　　域： [理学] [理学]