Molecular sieve

Molecular sieve is a material containing tiny pores of a precise and uniform size that is used for gas and liquid.
Molecules small enough to pass through the pores are adsorbed while larger molecules are not. It is different from a common filter in that it operates on a molecular level. For instance, a water molecule may be small enough to pass through while larger molecules are not. Because of this, they often function as a desiccant. A molecular sieve can absorb water up to 22% of its own weight.
Molecular sieves are often utilized in the industry, especially for the purification of gas streams and in the chemistry laboratory for separating compounds and drying reaction starting materials.
The content of natural gas is extremely harmful to the aluminium piping and other parts of the liquefaction apparatus-is used in this case.

Methods for regeneration of molecular sieves include pressure change (as in oxygen concentrators),heating and purging with a carrier gas (as when used in  dehydration), or heating under high vacuum.

3A (pore size 3 Å): Adsorbs NH3, H2O, (not C2H6), good for drying polar liquids.
Molecular Sieve 3A is an alkali metal alumina-silicate; it is the potassium form of the type A crystal structure. Type 3A has an effective pore opening of about 3 angstroms (0.3nm). This is large enough to allow in moisture, but excludes molecules such as unsaturated hydrocarbons which can potentially form polymers; and this maximizes lifetime when dehydrating such molecules.
Often they consist of aluminosilicate minerals, clays, porous glasses, micro porous charcoals, zeolites, active carbons, or synthetic compounds that have open structures through which small molecules, such as nitrogen and water can diffuse.

4A (pore size 4 Å): Adsorbs H2O, CO2, SO2, H2S, C2H4, C2H6, C3H6, EtOH. 4A oecular sieve will not absorb C3H8 and higher hydrocarbons.
Good for drying non-polar liquids and gases.