Adsorption function: from physical adsorption to material sources of molecular sieve (van Edward), polar and Coulomb field strong crystal internal cavity, the polar molecule (such as water) and unsaturated molecules exhibit strong adsorption capacity.
Screening function: the aperture is very homogeneous distribution of molecular sieve, bughole internal material only molecular diameter less than the diameter of the aperture can enter the molecular sieve.
The molecules of different substances are distinguished by the priority and size of the adsorption, so they are called "molecular sieves" by the image".