According to the molecular size, a physical exclusion effect is carried out.

1, adsorption function: molecular sieve is mainly influenced by molecular gravity, which produces a kind of "surface force" on the fixed surface. When the fluid flows, some molecules in the fluid will make irregular movements and collide with the surface of the adsorbent, resulting in molecular concentration on the fixed surface. In the whole collision movement, the number of molecules decreases, thus achieving the separation effect. Because of the strong polarity and Coulomb field in the crystal cavity of molecular sieve, it shows strong adsorption ability for polar molecules (such as water) and unsaturated molecules.

2. Drying function: The molecular sieve still has strong polarity in the crystal cavity, which can interact strongly with molecules containing polar groups on the surface of zeolite molecular sieve, or polarize polarizable molecules through induction to produce strong adsorption. Because molecular sieve has strong adsorption capacity for water and carbon dioxide, when molecular sieve is used for desulfurization, it has strong adsorption capacity for polar small molecules such as water.

3. Screening function: Its pore size distribution is very uniform and tidy. When the molecular diameter is smaller than the pore diameter, substances will enter the crystal cavity of the molecular sieve. So as to separate various types of molecular sieves. The types of molecular sieves are classified into 3a, 4a, 5a, etc. When they are used in different industries and achieve different use effects, they should be correctly selected according to the performance of different products.