不同热处理方式对超细粒子K-Co-Mo催化剂性能和结构的影响  

EFFECTS OF HEAT TREATMENT ON STRUCTURE AND PROPERTIES OF ULTRAFINE K-Co-Mo CATALYSTS

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

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

出　　处：《燃料化学学报》2001年第1期60-64,共5页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金! (2 97730 42 );安徽省自然科学基金! (985 114 37);北京同步辐射装置重点课题基金&&

摘　　要：以柠檬酸为络合剂 ,采用溶胶 凝胶法制备Co Mo超细粒子氧化物 ,所得干凝胶分别置于空气和氩气中进行焙烧 ,然后经K2 CO3 助化后硫化。使用X射线衍射 (XRD) ,BET比表面测试和扩展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活性。XRD结果表明 ,在空气中焙烧的样品为单一的CoMoO4 物种 ,其晶粒尺寸约为 6 0nm ;在氩气中焙烧的样品 ,柠檬酸的分解对样品起到还原作用 ,主要物种为CoMoO3,同时存在少量的CoMoO4 ,晶粒尺寸约为 2 0nm。BET结果表明 ,在氩气中焙烧的样品具有较大的比表面积。硫化态样品中主要物种为MoS2 和Co9S8,此外 ,还可能存在CoMoS3 13 物种。XRD和EXAFS结果均表明 ,在氩气中焙烧的样品硫化后 ,其晶粒尺寸相对较小。活性测试结果表明 ,催化剂晶粒尺寸的降低明显促进了合成醇的活性和选择性的提高。Co-Mo ultrafine particles were prepared by sol-gel method with citric acid as a complexant. The obtained dried gel was calcined in air and argon atmospheres, respectively. After promoting by K 2CO 3 and sulfiding, the two catalysts were measured in mixed alcohol synthesis from syngas. The XRD results showed that the Co-Mo particles treated in air were single CoMoO 4 crystallites with average size of 60nm. For the sample treated in argon, the main species in the sample were CoMoO 3, besides, some CoMoO 4 existed, and the average size was about 20nm. These results indicated that the decomposition of citric acid reduced the CoMoO 4 species and decreased the particle size remarkably. BET measurements showed that, treating the dried gel in argon, the obtained Co-Mo particle and corresponding sulfided sample possessed a larger surface area. For the sulfided catalysts, MoS 2 and Co 9S 8 species were detected by XRD, additionally, CoMoS 3.13 species may also existed. Both the XRD and EXAFS results indicated that the sulfided sample whose precursor treated in argon possessed smaller average size. The catalytic activity measurement showed that the decrease of the particle sizes resulted in better properties for mixed alcohol synthesis.

关 键 词：溶胶-凝胶法 热处理方式 催化活性 低碳醇 合成 结构 一氧化碳 加氢 钾钴钼催化剂 

分 类 号：O623.411[理学—有机化学] O643.361[理学—化学]