氢气还原对钴铝尖晶石结构及催化活性的影响  

The Influence of the Hydrogen Reduction on the Structure and Catalytic Activity of CoAl_2O_4 Spinel Catalysts

作　　者：吴银素[1] 张玉霞[1] 芦佳[1] 马子川[1] 

机构地区：[1]河北师范大学化学与材料科学学院,河北石家庄050016

出　　处：《河北师范大学学报（自然科学版）》2010年第2期192-198,202,共8页Journal of Hebei Normal University：Natural Science

基　　金：河北省教育厅科研基金(2008128);河北师范大学博士基金(L2005B16);河北师范大学一般基金(L2006Y04)

摘　　要：以异丙醇铝和硝酸钴为前驱体,采用溶胶-凝胶法制备了系列CoAl2O4类催化剂,并以邻二甲苯为目标污染物评价了氢气还原对CoAl2O4类催化剂活性的影响,考察了n(Co)/n(Al)、还原温度和接触时间等对催化剂活性的影响.结果表明:当n(Co)/n(Al)为0.5,500℃氢气还原处理的CoAl2O4在4000h-1空速下,可使φ为0.08%邻二甲苯在275℃完全转化为CO2和H2O,其完全转化温度较未还原的CoAl2O4催化剂降低了100℃.BET,XRD和XPS测试结果显示,经500℃氢气还原处理后CoAl2O4结晶程度降低,表面积明显增大.而且,还原还引起了Co的2p和Al的2p结合能的低移和晶格氧含量的增加.A series of COAl2O4 spinel catalysts were prepared by Sol-Gel method using aluminium isopropoxide and cobalt nitrate as precursors. The catalysts were used for deep catalytic oxidation of o-xylene after reduction in hydrogen. The influences of n （Co）/n （Al）, reduction temperatures and contacting time on the catalytic performance were primarily investigated. The results showed that the CoAl2O4 spinel reduced at 500 ℃ could convert 0.08 % of o-xylene into CO2 and H2O at 275℃ ,which was 100 ℃ lower than that of the unreduced catalyst. BET, XRD characterization results showed that hydrogen reduction caused the decrease of crystallization degree and grain size of the COAl2O4 spinel and then increased its surface area. XPS study revealed that the energy of Co 2p and AI 2p of the reduced-CoA120, spinel both shifted to lower values compared with unreduced catalyst. Moreover, the contents of lattice oxygen COAl2O4 spinel increased after hydrogen reduction.

关 键 词：CoAl2O4 氢气还原 邻二甲苯 深度催化氧化 

分 类 号：O643[理学—物理化学]