【摘要】 本文采用PASCA（化学分析正电子湮没谱）技术,系统地研究了MoO₃/γ-Al₂O₃,CoO/γ-Al₂O₃,MoO₃/TiO₂-Al₂O₃,CoO/TiO₂-Al₂O₃等体系中活性组分的表面分散状态和化学状态及其变化规律,揭示了用TiO₂改性Al₂O₃对Mo-Co系加氢精制催化剂所产生的载体效应的作用机理。Al₂O₃中引入TiO₂使得载体与MoO₃间的相互作用大大减弱,导致分散态MoO₃易于还原和硫化。助剂CoO与TiO₂-Al₂O₃载体间存在极为显著的电子相互作用,对于改善Co在活性相中的化学状态,提高活性中心的内在活性具有重要的作用。PASCA研究的另一个重要结果是,由于载体表面的不均匀性,使得上述负载型催化剂中氧化物活性组分的表面状态十分复杂,存在与载体相互作用强弱程度不同的多类特征区,这些特征区与内在活性不同的催化中心相关联。通过TiO₂改性Al₂O₃载体,有效地调节载体表面性质,改变活性组分表面物种的分布及化学状态。更多还原

【Abstract】 A novel type of TiO₂ modified alumina carrier was prepared to investigate the carrier effect of Mo-Co type hydrotreating catalysts as compared with alumina using PASCA technique. It was found that three different molydena surface species located at three diffierent sites on either alumina carrier or TiO₂ modified alumina. However, the fraction and characteristic for each sort of surface sites on the alumina carrier are quite different from those on TiO₂ modified alumina, The interaction between MoO₃ and the surface of carrier was weakened remarkably by addition of TiO₂, which leads to an in crease of polymolybdate-like surface species （active phase）. The synergism of Co-Ti was verified and the nature of it might be the electron interaction.更多还原