中国炼油与石油化工

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La和Ce调变Y分子筛性能的差异及其密度泛函理论研究

于善青1,田辉平,代振宇2,龙军2   

  1. 1. 石油化工科学研究院14室
    2. 石油化工科学研究院
  • 收稿日期:2010-07-16 修回日期:2010-11-01 出版日期:2011-03-31
  • 通讯作者: 于善青

Different Influences of Lanthanum and Cerium on Stability of Y Zeolite and Their Theoretical Calculations of DFT

  • Received:2010-07-16 Revised:2010-11-01 Online:2011-03-31

摘要: 本文采用XRD、XPS、MAS NMR等分析方法,研究了La、Ce增强Y分子筛结构稳定性的差异。结果表明,稀土离子La和Ce的引入,均能稳定Y分子筛的骨架结构,但是在稀土含量相当的情况下,La离子比Ce离子更容易进入分子筛内部,更能抑制骨架铝的脱除,对分子筛结构稳定作用更优。并结合量子力学密度泛函计算方法,从理论上进行了阐述:La离子或Ce离子的引入能显著增加分子筛骨架Al和相邻O原子的作用力,有效稳定分子筛骨架铝位,并且稀土离子与分子筛间存在较强的作用力;与Ce离子相比,La离子与分子筛的相互作用更大,Al-O作用力更强,因此,La离子比Ce离子更有利于稳定分子筛的骨架结构。

Abstract: In this paper, the different influence of Lanthanum and Cerium cation on the stability of Y zeolite was studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), multinuclear (27Al, 29Si) solid-state nuclear magnetic resonance spectroscopy (NMR). It was found that although the stabilization of Y zeolite could be enhanced by the introduction of Lanthanum or Cerium cation, the former was more remarkable than the later. These results were also confirmed theoretically by density functional calculations. There was a strong interaction between rare earth species and Y zeolite clusters, which restrained the formation of extra-framework alumina and enhanced evidently the stability of Y zeolite. Furthermore, the interaction between Lanthanum species and Y zeolite was stronger.