【摘要】 采用XRD及XPS技术研究了合成低碳醇反应中还原温度对还原态超细K-Co-Mo催化剂结构的影响.分别考察未还原及不同的还原温度下K、Co和Mo活性物种的价态以及相对含量的变化.结果表明:表面上Mo主要以+4和+6两种价态存在.随还原温度的升高,表面上Mo4+/Mo6+比增大,较高的Mo4+/Mo6+比有利于形成合成醇反应中活性位.Co也是以+2和金属态两种价态存在.还原温度低于500℃时,表面上Co2+的相对含量变化不大,但是在体相中可以检测到有金属Co形成,且随还原温度的升高而增多.当还原温度为550℃时,表面上的Co2+迅速减少,这种表面上的Co2+的迅速减少可能导致了合成醇活性的迅速降低.K+在还原温度低于500℃时相对含量没有明显变化,经550℃还原后,K+在表面明显富集.更多还原

【Abstract】 An ultra-fine K-Co-Mo catalyst at different reduction temperature used in mixed alcohols synthesis was characterized by XRD and XPS. The valence and relative content of the active species （K、 Co、 Mo） in this catalyst at different reduction temperature were investigated. The results indicate that the main valence of Mo is +4 and +6. The relative content of Mo⁴⁺ increases and the relative content of Mo⁶⁺ decreases when the reduction temperature is raised. The Co exists as Co²⁺ and metal. When the reduction temperature is less than 500 ℃, the relative content of Co²⁺ in the surface is almost constant; but at the inner of the catalyst, the metal Co is formed and becomes more when the reduction temperature is raised. When the reduction temperature is raised to 550 ℃, the content of Co²⁺ in the surface decreases remarkably. It is possible that this decrease of Co²⁺ in the surface leads to the decrease in mixed alcohols synthesis activity. When the reduction temperature is less than 500 ℃, the content of K⁺ in the surface is almost the same too, but when the reduction temperature is raised to 550 ℃, the K⁺ is enriched remarkably in the surface. The higher Mo⁴⁺/ Mo⁶⁺ is favorable to engender active site in mixed alcohol synthesis, and Co²⁺ is a very important factor that can affect the activity of the mixed alcohols synthesis.更多还原