改性γ-Al_2O_3载体上钴和钼的分散状态

Dispersion of Cobalt and Molybdenum on Phosphorus or Potassium Modified γ Al 2O 3 Support

利用ＸＲＤ、ＢＥＴ磁性分析等手段研究了在磷或钾改性的γ－Ａｌ２Ｏ３上钴和钼的存在形态，在Ｃｏ－Ｍｏ／γ－Ａｌ２Ｏ３负载型催化剂中，载体γ－Ａｌ２Ｏ３的改性处理对钴和钼的分散程度有显著影响．用磷酸处理γ－Ａｌ２Ｏ３载体时，由于载体的表面形成了类似ＡｌＰＯ４式的结构，从而抑制了Ｍｏ－Ｏ－Ａｌ的生成，使钼以ＭｏＯ３的形式存在．而在此载体上，弱碱性的钴则与磷酸在γ－Ａｌ２Ｏ３表面形成了类似磷酸钴式的结构，达到了较均匀的分散．用碳酸钾处理γ－Ａｌ２Ｏ３载体时，载体表面的强碱性抑制了钴的分散，使之形成了较大的Ｃｏ３Ｏ４晶粒．相反。

The dispersion of Co and Mo on phosphorus and potassium modified γ Al 2O 3 was investigated by X ray diffraction, BET surface areas and magnetic susceptibility analysis. It was found that molybdenum can no longer reach a single layered dispersion as it does on γ Al 2O 3 support, but forms large crystallite of MoO 3 on the H 3PO 4 treated γ Al 2O 3 support. While, cobalt oxide is highly dispersed with the help of phosphorus treatment. The resulting surface cobalt compound was recognized as staying in the tetrahedral coordination state. A AlPO 4 like surface compound on the phosphorus modified γ Al 2O 3 was supposed and the influence of phosphorus on the dispersion of Co and Mo was explained accordingly. Effects of potassium on the dispersion of Co and Mo were also reported and discussed here in.