Molecular Sieves

Molecular sieve (also called synthetic zeolite) is a kind of microporous aluminosilicate crystal. Its basic skeleton structure consists of silicon oxide, aluminum oxide tetrahedral. There are metal cation in its crystal lattice (such as Na +, K +, Ca2 +, Li +, etc.), these cation can balance the excess negative charge. According to their type of zeolite crystal structure is divided into A type, X type, Y type. According to molecular sieve aperture size, there are 3A, 4A, 5A, 10X, 13X. 4A molecular sieve is Na-A molecular sieve, aperture 0.4nm; if Na replaced by K, aperture 0.3nm, is 3A molecular sieve; if over 1/3 Na replaced by Ca2+, aperture 0.5nm, is 5A molecular sieve.
Molecular sieve adsorption capacity come from physical adsorption (Van der Waals forces), its cavities have a strong polarity and coulomb field which show a strong adsorption capacity to polar molecules (such as water) and unsaturated molecules. Molecular sieve has a uniform pore structure, which can separate different polarity, different saturation, different sizes and different boiling molecules. It has the effect of