Molecular sieve is a crystallization of silicon aluminium salts, due to its uniform aperture and high surface, so has many excellent features:

1. Adsorb according to the size and shape of the different aperture, i. e. only adsorb those small apertures, which have sameer size and shape of the molecular sieve;

2. For small polarity molecules and unsaturated molecules, the higher the degree of saturation and polarity, the selective absorption is more stronger;

3. Strong water absorption, even at high temperature, low water content situation , they still have quite high absorption capacity.

Its main types are 3A, 4A, 5A, 10X, 13X and copper sieve etc.