Molecular Sieve (as known as synthetic zeolite) is a micro-porous aluminosilicate crystals. It is made of silicon-oxy tetrahedron, alumina tetrahedron to form a basic skeleton structure, in which exist metal cations (e.g. Na+, K+, Ca2+, etc.) to balance the excess negative charge in the crystal. According to the type of crystal structure, zeolite consists of: A-type (LTA), X-type (FAU), Y-type and so on.
The chemical formula of zeolite unit cell:
Mx/n [ (AlO2)x (SiO2)y ] ·H2O
Mx/n: Metal cations, to maintain charge balance in crystal
(AlO2)x(SiO2)y: Skeleton of zeolite, with different shapes hole and pore
H2O: Chemical and physical adsorption of water, physical adsorption of water can desorption under certain conditions