Electronic Resource
Springer
Journal of inclusion phenomena and macrocyclic chemistry
21 (1995), S. 1-46
ISSN:
1573-1111
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Molecular sieves are inorganic framework structures generally composed of crystalline aluminosilicate tetrahedra which are arranged to form channels of 2–10 Å, diameters and cages with dimensions from 6–15 Å. Absorption of probe molecules of varying geometries and sizes is used to characterize the framework dimensions and topography in concert with X-ray diffraction identification of the specific structure. From unit cell dimensions and assumptions about the size of the framework forming species, a pore volume can be calculated. The volumes of the absorbed probe molecules, using their liquid densities, are then compared to the calculated pore volume. The constraint on the packing of the absorbed molecules is quantified by comparing their packing density to their density in the liquid state. Further, the packing of different probe molecules into the same pore volume is compared via a ratio technique called the ‘packing ratio’. The effect of the lattice geometry and framework dimensions on the ‘packing ratios’ is to provide a set of characteristic values for a given molecular sieve. The packing ratios for zeolites rho and ZSM-5 are presented as expectation values for other scientists to use as bases of comparison.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00709410
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