摘要
用NH_4BF_4,(NH_4)_3ZrF_7(NH_4)_2TiF_6(NH_4)_3FeF_6和CrF_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人沸石骨架,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.
Isomorphous substitution of heteroatoms for Y zeolite in aqueous solutions of NH4BF4, (NH4)3ZrF7, (NH4)2TiF6, (NH4)3FeF6 and CrF3 · 3NH4F has been studied. All the heteroatoms except B have been substituted into the zeolite framework, and the extent of substitution is in the order of Fe>Ti>Cr≈Zr. The heteroatom substituted Y zeolites have been analyzed and characterized by XRD, IR and DTA methods, showing that the heteroatoms are located in the zeolite framework. Based on the mechanism of the isomorphous substitution, the main factors affecting the substitution have been discussed. It has been suggested that the feasibility and the extent of isomorphous 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 polymerization equilibrium constant of the metal hydroxide.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1995年第2期135-140,共6页
Acta Chimica Sinica
基金
国家自然科学基金重点项目
中国石油化学工业总公司资助的课题
