Molekulaarsõelu

Molekulaarsõelu, also known as molecular sieves, are crystalline solids with a uniform pore structure. These pores are of a size that allows small molecules to pass through while excluding larger ones. This selective adsorption capability makes them highly useful in a variety of industrial and laboratory applications.

The primary characteristic of molecular sieves is their precisely defined pore diameter, typically measured in angstroms (Å) or nanometers (nm). Common pore sizes range from 3Å to 10Å, with specific types designed for particular separation tasks. They are often composed of aluminosilicates, commonly known as zeolites, but can also be made from other materials such as activated carbon or silica gel.

The mechanism of separation relies on the difference in size and shape between the molecules of the mixture and the pores of the sieve. Molecules that are smaller than the pore openings can enter the internal structure of the sieve and be adsorbed, while larger molecules are physically excluded. This process is highly effective for separating gases and liquids.

Applications of molecular sieves are widespread. They are extensively used in the petrochemical industry for gas drying and purification, such as removing water from natural gas or separating olefin isomers. In laboratories, they are employed for drying solvents and removing trace impurities. Their ability to selectively adsorb specific molecules also finds use in catalysis, chromatography, and as desiccants. The regeneration of molecular sieves is typically achieved by heating them to desorb the adsorbed molecules, allowing for their reuse.