化学学报 ›› 1995, Vol. 53 ›› Issue (2): 135-140. 上一篇    下一篇

研究论文

杂原子对Y沸石液固相类质同晶取代规律探讨

高滋;徐金锁   

  1. 复旦大学化学系
  • 发布日期:1995-02-15

Studies on the regularities of the isomorphous substitution of heteroatoms for zeolite Y in aqueous solution

GAO ZI;XU JINSUO   

  • Published:1995-02-15

用NH~4BF~4,(NH~4)~3ZrF~7,(NH~4)~2Tif~6,(NH~4)~3FeF~6和CrF~3,3NH~4F等溶液为取代剂,对Y沸石实行液固相类质同晶取代,除了B以外, 其它金属元素均能代入沸石骨架,它们的取代程度为Fe>Ti>Cr≈Zr.采用XRD,IR和DTA 等手段对取代产物进行表征,证实杂原子已成为骨架元素.由液固相类质同晶取代机理出发, 对影响杂原子取代程度的主要因素进行了探讨,提出由杂原子的离子半径.含氟配合物累积稳定常数. 阳离子水解平衡常数和水解产物聚合平衡常数可以预测各种杂原子的取代效果.

关键词: 红外分光光度法, 沸石, X射线衍射分析, 示差扫描量热法, 氟化铵, 氟硼铵, 氟锆铵, 氟钛铵, 氟化铬

Isomorphic substitution of heteroatoms for Y zeolite in aqueous solns. of NH4BF4, (NH4)ZrF7, (NH4)TiF6, (NH4)FeF6, and CrF3.3NH4F was studied. All the heteroatoms except B are substituted into the zeolite framework, and the extent of substitution is in the order Fe > Ti > Cr u Zr. The heteroatom substituted Y zeolites are analyzed and characterized by x-ray diffraction, IR, and DTA methods, showing that the heteroatoms are located in the zeolite framework. In terms of the isomorphic substitution the mechanism, the main factors affecting the substitution are discussed. The feasibility and the extent of isomorphic substitution of a heteroatom in aqueous solution of a fluorocomplex can be predicted from the ionic radius of the heteroatom, the cumulative stability constants of the fluorocomplex, the hydrolysis equilibrium constant of the metal cation, and polymerisation equilibrium constant of the metal hydroxide.

Key words: INFRARED SPECTROPHOTOMETRY, ZEOLITE, X-RAY DIFFRACTION ANALYSIS, DIFFERENTIAL SCANNING CALORIMETRY, AMMONIUM FLRORIDE, CHROMIC FLUORIDE

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