溶胶-凝胶法制备K-Co-Mo催化剂的结构及其合成低碳醇性能研究──焙烧温度的影响  

Structure of K\|Co\|Mo Catalysts Prepared by Sol\|gel Method and their Catalytic Performance for Mixed Alcohol Synthesis — Effect of Calcination Temperature

作　　者：鲍骏[1] 卞国柱[1] 伏义路[1] 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》1999年第4期253-258,共6页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金;安徽省自然科学基金

摘　　要：采用溶胶凝胶法制备 Ｃｏ Ｍｏ Ｏ４ 催化剂， 经 Ｋ 助化后分别在空气中于４００～８００ ℃下进行焙烧， 得到氧化态样品， 然后经硫化制得硫化态 Ｋ Ｃｏ Ｍｏ 催化剂， 对氧化态样品的乙醇分解性能及硫化态样品的 Ｃ Ｏ 加氢合成低碳醇的反应性能进行了测试． 运用 Ｘ 射线衍射（ Ｘ Ｒ Ｄ ）和扩展 Ｘ光吸收精细结构（ Ｅ Ｘ Ａ Ｆ Ｓ ）对样品进行结构表征． 乙醇分解性能测试表明， 催化剂的表面酸性较弱， 且随着焙烧温度的升高变化不大． 合成醇性能测试结果则显示， 催化剂的焙烧温度升高后，其合成醇的产率逐步降低， 但醇选择性基本不变． 经 ４００ ℃焙烧的样品， 具有最好的催化活性．结构分析结果表明， 氧化态样品中存在多种 Ｋ Ｍ ｏ Ｏ 物种， 且随着焙烧温度的提高， 钾钼之间作用增强， 样品更难以被完全硫化．Co\|Mo composite oxide catalyst prepared by the sol\|gel method with citric acid as complexant is promoted with K 2CO 3 and followed by calcination in air at different temperatures. The obtained samples are then sulfided in a flow of CS 2/H 2(30 mL/min) at 400 ℃ for 6 h. The activity of these sulfided samples for the synthesis of mixed alcohol from CO hydrogenation has been investigated under the conditions of p=5.0 MPa, T=310 ℃ and GHSV=4 800 h -1 . The results show that the Space\|Time\|Yields(STY) of mixed alcohol decrease remarkably with the increase of calcination temperature. The catalyst calcined at 400 ℃ has the best performance in the mixed alcohol synthesis. Structures of the oxidized and the sulfided K\|Co\|Mo samples were characterized by XRD and EXAFS. The XRD results show that some K\|Mo\|O species exist in the oxidized samples. With increasing the calcination temperture, the K\|Mo interaction is enhanced remarkably. The XRD and EXAFS results indicate that after sulfidation Co species exist as Co 9S 8 and Mo as MoS 2 crystallites. With rising calcination temperature, the extent of sulfidation is decreased. The results of ethanol decomposition show that K\|Co\|Mo catalysts possess much weaker surface acidity comparied with γ\|Al 2O 3.

关 键 词：溶胶-凝胶法 催化剂 焙烧 结构 钴 钼 钾 

分 类 号：O643.36[理学—物理化学] TQ426.6[理学—化学]