合成低碳醇超细Mo-Co-K催化剂局域结构的研究

采用类凝胶法和超临界流体干燥技术制得了一组具有不同Co/Mo比的超细非负载型Mo Co K催化剂 ,考察了其合成低碳醇性能 ,并运用EXAFS技术对还原态催化剂的局域结构进行了研究。结果表明 ,还原态催化剂中Co以CoMoO4的形式存在 ,Co的配位数低于标样CoMoO4的配位数 ,且随着Co/Mo比的减小而减小。由于催化剂中Mo与Co之间的相互作用 ,使得Co O键长被不同程度地拉长。研究表明 ,催化剂中具有低配位Co且较弱的Mo、Co之间相互作用的类CoMoO4结构物相可以促进低碳醇的生成。

An EXAFS study of ultrafine Mo-Co-K catalysts for the synt hesis of higher alcohols

A series of reduced unsupported ultrafine MoCoK catalysts with different Co/Mo ratios were prepared by the gellike method and followed by the supercritical fluid drying technique.The catalysts with different performance were investigated by the extended Xray absorption fine structure(EXAFS)technique.The performance of the catalysts was found to be closely related to their local structure.The EXAFS results showed that Co was present in a distorted CoMoO_4,and the coordination numbers of Co were less than that of the model CoMoO_4 and decreased with a reduction of Co/Mo ratio.Because of the interaction between Co and Mo,the CoO bond was stretched to some extent compared with CoMoO_4.It was found that the CoMoO_4 structure analogue with less Co coordination numbers and weak interaction of Co and Mo was favourable for the formation of higher alcohols.