硫化态CO-Mo-K/AC合成醇催化剂的EXAFS研究

摘要

The structures of sulfided Co-Mo-K/AC catalysts were studied by means of XRD and XAFS. Activities for mixed alcohol synthesis via CO hydrogenation were used to measure the catalytic properties of these catalysts. On the activated carbon support, molybdenum is mainly present as MoS2 species, while cobalt mainly in the form of "Co-MoS" phase with the low Co-loading and partly in a Co9S8-like structure with higher Co-loading. The catalysts demonstrate outstanding performance for higher alcohol synthesis with the promotion of cobalt. The activity for alcohol formation optimizes at Co/Mo atom ratio of 0.5 due to the maximum amount of surface"Co-Mo-S" active sites. Co species operate as a synergistic system, rather than independently from the intercalated MoS2 phase (physical mixture).%采用XRD、EXAFS等手段考察了Co载量对催化剂结构的影响，并关联其合成醇活性。活性炭担载的硫化态Co-Mo-K样品中，Mo主要以MoS2物种形式存在于活性炭的表面上，而Co在低Co载量时主要形成"Co-Mo-S"相，在高Co负载量会有部分类Co9S8的物相出现。经Co助剂修饰后的催化剂显示出良好的合成醇催化性能，Co助剂有利于合成C2+醇。Co/Mo原子比为0.5时，表面"Co-Mo-S"相可能达到饱和，合成醇的收率也最高。Co物种是和MoS2物相以协同的方式起作用的。