Zeolite is the general name of the crystal of porous aluminosilicate with frame structure.
Its general chemical formula as below
(Na，K)x(Mg，Ca，Sr，Ba)y[Alx +2ySin-(x +2y)].mH2O
X：number of alkali metal ions
Y：alkali earth metal ions
n：sum of the number of Al-S ions
m：Number of hydrone
Classification of Zeolite
Natural zeolite and synthetic zeolite
There are five kinds of natural zeolite with large scale industrial deposits including clinoptilolite, flokite, chabazite, erionite and phillipsite. But in China, normally only clinoptilolite and flokite are used widely.
In practical application, we normally use synthetic zeolite. There are type A, type X ,type Y.We have natural zeolite,but synthetic zeolite is more structured and more stable
Crystal structure of Zeolite
In zeolite minerals there are 80% of SiO2 and Al2O3. But different Al-Si ratio forms different zeolite mineral species.Water is also the main component of zeolite.There is about 10%. But water does not participate in the framework of zeolite. It is only absorbed in the micro pore of zeolite crystal.
The main difference between different kinds of zeolite is that they have different framework. The framework is a 3D spatial structure formed with O2,Si, Al not including alkali,alkali earth and water.
All kinds of zeolites have their special shape and size of void and channel so they can adsorb and retain different shape and size of molecule
Square sodium type，such as type A:K A(3A),Na A(4A),Ca A(5A)；
Octahedral type，such as type X: Ca X(10X),Na X(13X)and type Y: Na Y,Ca Y；
Flokite type，（-M）：High Si zeolite，such as ZSM-5etc.
Chemical Formula of Zeolite molecular sieve
Molecular sieve 3A
Chemical Formula 2/3K2O . 1/3Na2O . Al2O3 . 2SiO2 . 9/2H2O
Si-Al ratio：SiO2/Al2O3≈2
Molecular sieve 4A
Na2O . Al2O . 2SiO2 . 9/2H2O
Si-Al ratio：SiO2/Al2O3≈2
Molecular sieve 5A
Chemical Formula：3/4CaO . 1/4Na2O . Al2O3 . 2SiO2 . 9/2H2O
Si-Al ratio：SiO2/Al2O3≈2
Rich Oxygen molecular sieve 5A
Chemical Formula 4/5CaO . 1/5Na2O . Al2O3 . 2SiO2
Si-Al ratio：SiO2/Al2O3≈2 mainly used for PSA oxygen generation
Molecular sieve 10X
Chemical formula : 4/5CaO . 1/5Na2O . Al2O3 . (2.8±0.2)SiO2 . (6-7)H2O
Si-Al ratio：SiO2/Al2O3≈2.6-3.0 effective aperture：about 9A
Molecular sieve 13X
Chemical formula : Na2O . Al2O3 .（2.8±0.2）SiO2 . （6-7）H2O
Si-Al ratio：SiO2/AL2O3≈2.6-3.0 effective aperture：about 10A
Zeolite molecule structure
1–a cage（Cubic lattice with β cage as particle）,
2–octagonal cage
3—cubic cage,
4—βcage（basic unit for synthetic zeolite 4A、X、Y,angled octahedron
5—six column cages,
6—r cage ,
7—octagonal cage
Cage β is formed with 8 six-membered ring and 6 four-membered ring.
8 β cages connected with four-membered ring is called α cage.
