Molecular sieve

Molecular sieve refers to a class of substances with uniform micropores whose pore size is comparable to that of general molecular size. Commonly used molecular sieves are crystalline silicates or aluminosilicates, which are composed of silicon-oxygen tetrahedrons or aluminum-oxygen tetrahedra connected by oxygen bridges to form a molecular size (usually 0.3~2 nm) channel and cavity system , has the ability to sieve fluid molecules of different sizes due to the size and shape of the adsorbed molecules.

According to its crystal structure, it is mainly divided into: A type, X type, Y type and so on. Molecular sieves often use prefix numbers to classify molecular sieves with different crystal structures, such as 3A type, 4A type, 5A type, 10X type, 13X molecular sieve, etc.

Adsorption function: The adsorption of molecular sieves to substances comes from physical adsorption, and its crystal pore size has strong polarity and adsorption capacity, and shows strong adsorption capacity for polar molecules (such as water) and unsaturated molecules.

Screening function: The pore size distribution of molecular sieve is very uniform. Only substances whose molecular diameter is smaller than the diameter of the inner cavity of the molecular sieve can enter the crystal cavity of the molecular sieve to achieve the purpose of adsorption and drying. The molecules of different substances are distinguished by the priority order and size of adsorption, so they are vividly called "molecular sieves".

Molecular sieves are widely used and can be used as high-efficiency desiccants, selective adsorbents, catalysts, ion exchangers, etc.