物理化学学报 >> 1993, Vol. 9 >> Issue (05): 650-656.doi: 10.3866/PKU.WHXB19930515

研究论文 上一篇    下一篇

K-MoO3/γ-Al2O3催化剂表面物种状态、组成和性能

卞国柱; 姜明; 伏义路; 季明荣   

  1. 中国科学技术大学近代化学系，合肥 230026；中国科学院中国科学技术大学结构成份分析开放实验室，合肥 230026
  • 收稿日期:1992-04-17 修回日期:1992-10-06 发布日期:1993-10-15
  • 通讯作者: 伏义路

Chemical States and Composition of the Surface Species of K-MoO3/γ-Al2O3 Catalysts

Bian Guo-Zhu; Jiang Ming; Fu Yi-Lu; Ji Ming-Rong   

  1. Department of Modern Chemsitry, University of Sciences and Technology of China, Hefei 230026; Laboratory of Structure Research, University of Science and Technology of China, Academia Sinica, Hefei 230026
  • Received:1992-04-17 Revised:1992-10-06 Published:1993-10-15
  • Contact: Fu Yi-Lu

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摘要： 应用XPS、XRD、ESR 和TPR技术分析了KCl助剂含量变化对MoO_3/γ-Al_2O_3催化剂表面物种状态、组成及其硫化还原性能的影响. K/Mo比小于0.8时, 钾离子完全和钼作用, 形成钾钼作用物种, 催化剂硫化后发生K~+表面富集, Cl~-游离并流失; K/Mo比0.8时, 钾钼作用达到饱和; K/Mo比大于0.8时, 多余的K~+和Cl~-结合以体相KCl形式存在. 钾钼作用减弱了Mo(Ⅵ)和载体之间的作用, 部分抑制了Mo(Ⅵ)的硫化还原. 钾钼作用物种硫化后可能产生CO合成醇的活性中心.

关键词: 钾助剂, K-MoO3/γ-Al2O3催化剂, 结构表征, 硫化还原

Abstract: The chemical states and composition of the surface species of sulfided MoO_3/γ-Al_2O_3 catalysts with the promotion of variable KCI contents have been investigated and correlated to the sulfidation and reduction properties of the catalysts by means of XPS, XRD, ESR and TPR techniques. An interaction between the potassium cations and the molybdenum component occurred and was stoichiometrically saturated at a KCI loading with the K/Mo atomic ratio of 0.8. At the K/Mo ratios below 0.8 the potassium cations interacted with molybdenum component to form the interacting species and were enriched on the catalyst surface, while chloride anions were free and lost during preparation. At the K/Mo ratios above 0.8 the surplus potassium cations directly combined with the chloride anions to form bulk KCl crystallites. Due to the existence of the potassium promoter, the interaction between the supported Mo(VI) and the γ-Al_2O_3 became weaker and the sulfidation and reduction for catalysts were partly retarded. The active sites or phases, which were responsible for the alcohol formation activity, could be produced by sulfiding the interacting species composed of the potassium and molybdenum components.

Key words: Potassium promoter, K-MoO3/γ-Al2O3 catalysts, Structure characterization, Sulphidation, Reduction