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A molecular sieve is a material with pores (voids or holes), having uniform size comparable to that of individual molecules, linking the interior of the solid to its exterior. These materials embody the molecular sieve effect , the preferential sieving of molecules larger than the pores.
Size-exclusion chromatography, also known as molecular sieve chromatography, [1] is a chromatographic method in which molecules in solution are separated by their shape, and in some cases size. [2] It is usually applied to large molecules or macromolecular complexes such as proteins and industrial polymers . [ 3 ]
The typical molecular sieve used is a synthetic zeolite with a pore diameter around 0.4 nanometer ( Type 4A ) and a surface area of about 500 m 2 /g. The sorption pump contains between 300 g and 1.2 kg of molecular sieve. A 15-liter system will be pumped down to about 10 −2 mbar by 300 g molecular sieve. [1]
Equivalent spherical diameter for the sieve method. In sieve analysis, the particle size distribution of a granular material is assessed by letting the material pass through a series of sieves of progressively smaller mesh size. In that case the equivalent spherical diameter corresponds to the equivalent sieve diameter, or the diameter of a ...
The term molecular sieve refers to a particular property of these materials, i.e., the ability to selectively sort molecules based primarily on a size exclusion process. This is due to a very regular pore structure of molecular dimensions.
The discovery of a new family of mesoporous molecular sieves in the early 1990s by Kuroda et al., known as KSW-1 [1] and FSM-16, [2] and by ExxonMobil, called M41S, [3] opened new possibilities to prepare catalysts for reactions of relatively large molecules.