Au/α-Fe_2O_3催化剂存贮失活环境因素及机理分析  

Environmental Factors and Deactivation Mechanism of Au/α-Fe_2O_3 Catalyst during Storage in Ambient Air

作　　者：尉继英[1] 范桂芳[1] 江锋[1] 张振中[1] 张兰[1] 

机构地区：[1]清华大学核能与新能源技术研究院,北京100084

出　　处：《催化学报》2010年第12期1489-1495,共7页

基　　金：国家自然科学基金(21077064;20777046);清华大学985二期研究项目;清华大学测试基金的支持

摘　　要：采用沉积沉淀法制备了CO低温氧化催化剂Au/α-Fe2O3,通过X射线衍射、X射线光电子能谱、N2吸附-脱附、傅里叶变换红外光谱、H2程序升温还原和CO2程序升温脱附等手段对催化剂进行了表征,探讨了在室温大气气氛下光线照射以及表面吸附等环境因素所导致的催化剂存贮失活及其作用机理.结果表明,经110oC干燥的Au/α-Fe2O3催化剂表面同时存在Au3+和Auδ+(0≤δ≤1)物种,且前者催化CO氧化的活性更高;在室温大气气氛下,紫外线照射会引起Au3+的还原和Au颗粒的生长,导致催化剂的不可逆失活.此外,空气中的H2O和CO2可同时吸附在α-Fe2O3的表面,形成表面碳酸盐物种,会引起催化剂的可逆失活.Au/α-Fe2O3 catalyst samples were prepared by the deposition-precipitation method. By using CO oxidation as a probe reaction,combined with characterizations such as X-ray diffraction,X-ray photoelectron spectroscopy,N2 adsorption-desorption,Fourier transform infrared spectroscopy,H2 temperature-programmed reduction and CO2 temperature-programmed desorption,the environmental factors,such as irradiation and surface adsorption on the stored catalyst,resulting in the catalyst deactivation,were studied. The active Au species on the catalyst and the deactivation mechanism were investigated. The results show that Au3＋ and Auδ＋ （0 ≤ δ ≤ 1） species were coexisted on the surface of Au/α-Fe2O3 catalyst treated at 110 oC,and the catalyst activity follows the order Au3＋ Auδ＋. When stored in ambient air,UV irradiation can cause the reduction of oxidative Au species and the growth of Au particles. Meanwhile,CO2 and H2O in the atmosphere could be adsorbed on the surface of α-Fe2O3 to form some kinds of carbonates. Thus UV irradiation and surface carbonate adsorption may be the main factors resulting in the deactivation of Au/α-Fe2O3 catalyst during storage in ambient air.

关 键 词：金 三氧化二铁 一氧化碳 氧化 室温大气气氛 存贮 失活 碳酸盐 

分 类 号：O643.36[理学—物理化学]