DISTRIBUTION OF CATIONS IN LANTHANUM-EXCHANGED NAY ZEOLITES

被引：35

作者：

SHY, DS ^{[1
]}

CHEN, SH ^{[1
]}

LIEVENS, J ^{[1
]}

LIU, SB ^{[1
]}

CHAO, KJ ^{[1
]}

机构：

[1] NATL TSING HUA UNIV, DEPT CHEM, HSINCHU 300, TAIWAN

来源：

JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS | 1991年 / 87卷 / 17期

关键词：

D O I：

10.1039/ft9918702855

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The locations of the exchangeable cations of partially La-exchanged NaY zeolites (Si/Al = 2.29) in dehydrated and rehydrated states have been determined using powder X-ray diffraction and Xe-129 NMR and from the isotherm of adsorbed xenon. Most the La3+ ions in LaNaY tend to migrate irreversibly from supercages into sodalite cages or hexagonal prisms, while the Na+ ions prefer to stay in the supercages after sample dehydration treatment at 350-degrees-C. Sites I and II are occupied by La3+ and Na+ ions, respectively, while both Na+ and La3+ ions are located at site I'. The amount of La3+ ions in sodalite cages increases with the increase of La content and the readsorption of water. The occupancy of Na+ ions at site II was found to decrease with increasing degree of La exchange from both X-ray diffraction studies and from the xenon adsorption isotherm. Xe-129 NMR results indicate that the nature of intersupercage void space is similar for LaNaY and NaY.

引用

页码：2855 / 2859

页数：5

共 35 条

[1]

BARRER RM, 1971, ADV CHEM SER, V102, P105

[2]

BARRIER RM, 1978, ZEOLITES CLAY MINERA, P87

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