超细粒子K-Co-Mo催化剂中钴含量对催化剂结构及其合成低碳醇性能的影响  

Catalytic Properties and Structure of Ultrafine K-Co-Mo Catalysts with Different Co Contents for Mixed Alcohol Synthesis

作　　者：鲍骏[1] 卞国柱[1] 伏义路[1] 刘涛[2] 谢亚宁[2] 胡天斗[2] 

机构地区：[1]中国科学技术大学化学物理系,合肥230026 [2]中国科学院高能物理研究所,北京100039

出　　处：《分子催化》2000年第5期349-353,共5页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金! ( No.2 97730 4 2 );安徽省自然科学基金!( No.98511437)资助项目

摘　　要：采用溶胶 -凝胶法 ,制备了不同钴含量的钴钼超细粒子氧化物 ,将其与 K2 CO3干混后进行硫化 .使用 X-射线衍射 (XRD)和扩展 X光吸收精细结构 (EXAFS)对样品进行结构表征 ,同时测试硫化态样品的 CO加氢合成低碳混合醇性能 .结构表征结果表明 ,不含钴的氧化态样品 ,主要以颗粒度较大的 Mo O2 物种存在 ;添加钴后 ,样品粒子的颗粒度大幅度降低 ,钴钼组分主要以 Co Mo O3物种的形式存在 ,当钴含量增加时 ,Co Mo O3的晶形趋于改善 .硫化态样品中钼以类似于 Mo S2 物种的形式存在 ,但粒子尺寸较小 .同时 ,体系中还存在 Co- Mo- S和Co9S8物种 .XRD和 EXAFS结果表明 ,适量钴的添加 ,有利于样品的硫化 .活性测试表明 ,钴的加入 ,明显促进了超细粒子催化剂合成醇的活性及 C2 +醇选择性的提高 ,其中 Co/Mo比为 1 .0 0的样品 ,活性最好 ,产物中 C2 +醇的含量也最高 .结合结构表征结果 ,认为钴是以协同作用的方式参与反应 .Ultrafine particles Co\|Mo with different Co contents were prepared by sol\|gel method. After promoted with K\-2CO\-3 by dry\|mixing and then sulfidation, they were used to measure the catalytic properties for mixed alcohol synthesis from syngas under the conditions of p =5.0 MPa, T =310 ℃ and GHSV=4 800 h\+\{-1\}. The obtained results show that the optimum Co content is Co/Mo (atomic ratio)=1, using which the space\|time\|yield and the selectivity to C\-\{2+\} alcohol are obviously higher than the others.\;The structures of K\|Co\|Mo samples were determined by X\|ray diffraction (XRD) and extended X\|ray absorption fine structure (EXAFS). The XRD patterns of oxidized samples are very broad at low Co/Mo, indicating that the particle size is small. The results of crystallographic analysis show that the main Co\|Mo species in the oxidized samples is CoMoO\-3, and some CoMoO\-4 species also exist. With the increase of Co content, the CoMoO\-3 diffraction peaks enhance remarkably, while the CoMoO\-4 diffraction peaks decrease slightly. After sulfidation, the XRD and EXAFS results indicate that Mo exists as MoS\-2\|like crystallites, and Co species exist as Co\-9S\-8 and Co species. It is suggested that the Co species in the catalysts participate in the alcohol synthesis reactions in a synergetic manner.

关 键 词：K-CO-MO催化剂 低碳醇 合成 钴含量 结构 CO 

分 类 号：O623.411[理学—有机化学] O643.36[理学—化学]