DIFFUSION ANISOTROPY IN MOLECULAR-SIEVES - A FOURIER-TRANSFORM PFG NMR-STUDY OF METHANE IN ALPO4-5

被引：46

作者：

NIVARTHI, SS ^{[1
]}

MCCORMICK, AV ^{[1
]}

DAVIS, HT ^{[1
]}

机构：

[1] UNIV MINNESOTA, DEPT CHEM ENGN & MAT SCI, MINNEAPOLIS, MN 55455 USA

来源：

CHEMICAL PHYSICS LETTERS | 1994年 / 229卷 / 03期

关键词：

D O I：

10.1016/0009-2614(94)01059-5

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：

By analyzing the shape of the H-1 PFG NMR spin echo decay of methane in large crystals of AlPO4-5, we demonstrate that diffusion of methane is unidirectional but not single file. The intracrystalline diffusion coefficient is 2.9 X 10(-9) m(2)s(-1). The same experiment, when performed on AlPO4-5 crystals of much smaller size, results in an isotropic diffusivity that is higher by nearly three orders of magnitude. This crystal size artifact emphasizes the importance of using large zeolite crystals in NMR measurements to obtain intracrystalline diffusivities.

引用

页码：297 / 301

页数：5

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