The adsorption principle of molecular sieve is based on its porous structure and selective adsorption characteristics. The pore size and shape of molecular sieve can be customized to meet different requirements, allowing for selective adsorption of molecules of various sizes. Adsorbates are fixed within the pores of the molecular sieve due to the adsorption forces, which typically include van der Waals forces and electrostatic attractions.

When the molecular sieve comes into contact with the adsorbate, the adsorbate is fixed within the pores of the molecular sieve due to the adsorption force. This adsorption process is typically accompanied by a heat release effect.

During the desorption process, certain means like increasing temperature or decreasing pressure are employed to reduce the adsorption force of the molecular sieve on the adsorbed substances, allowing them to desorb from the molecular sieve. The desorption process is typically accompanied by an endothermic effect.

In summary, the molecular sieve adsorption principle is a physical method that utilizes the porosity and selective adsorption characteristics of molecular sieves to separate and purify molecules of different sizes.