Molecular Sieve
Type

Typical Application

Molecular Sieve type 3A is an alkali metal alumino-silicate, potassium form of type A crystal structure. Type 3A has effective pore opening of about 3 angstroms (0.3nm) to allow moisture get into, but excludes molecules such as unsaturated hydrocarbons which can potentially form polymers;.

Drying of unsaturated hydrocarbons (e.g. ethylene, propylene, butadien)
Cracked Gas Drying
Drying of natural gas, if COS minimization is essential, or a minimum co-adsorption of hydrocarbons is required.
Drying of  highly polar compounds, such as methanol and ethanol
Drying of liquid alcohol with Z3-01 / 1-2 mm beads
Drying of refrigerants (e.g. R22, R134a etc)

Molecular Sieve type 4A is an alkali alumino silicate; sodium form of Type A crystal structure. 4A molecular sieve has an effective pore opening of about 4 angstroms (0.4nm). will adsorb most molecules with a kinetic diameter of less than 4 angstroms and exclude those larger. Such adsorbable molecules are oxygen, nitrogen, carbon dioxide and straight chain hydrocarbons. Branched chain hydrocarbons and aromatics are excluded.

Drying and removing of CO2 from natural gas, LPG, air, inert and athmospheric gases, etc.
Removal of hydrocarbons, ammonia and methanol from gas streams (ammonia syn gas treating)
Special types are used in the air break units of buses, trucks and locomotives.
Packed in small bags, it may be used simply as a packaging desiccant

Molecular Sieve type 5A is an alkali alumino silicate; calcium form of the Type A crystal structure. Type 5A has an effective pore opening of  5 angstroms (0.5 nm). It will adsorb molecules with a kinetic diameter of less than 5 Angstrom and exclude those larger. It is especially suitable for PSA adsorber applications where it may be used for the separation of normal- and iso-paraffins (C4 to C6 species), in PSA hydrogen purification and in oxygen concentrators.

The strong ionic forces of the divalent calcium ion makes it an excellent adsorbent to remove water, CO2, H2S from sour natural gas streams, while minimizing COS formation.  Light mercaptans are also adsorbed.
separation of  normal- and iso paraffins.

Production of high purity N2, O2, H2 and inert gases from mixed gas stream

Molecular Sieve 13X is the sodium form of the type X crystal and has a much larger pore opening than the type A crystals.  It will adsorb molecules with a kinetic diameter of less than 9 Angstrom (0.9 nm) and exclude those larger. It also has the highest theoretical capacity of the common adsorbents and very good mass transfer rates. It can remove impurities too large to fit into a type A crystal and is commonly used to separate nitrogen from oxygen.

Removal of CO2 and moisture from air (air pre-purification) and other gases.
Separation of enriched oxygen from air. 
Removal of mercaptans and hydrogen sulphide from natural gas.
Removal of mercaptans and hydrpogen sulphide from hydrocarbon liquid streams (LPG, butane, propane etc.)
Catalyst protection, removal of oxygenates from hydrocarbons (olefin streams). Removal of n-chained compositions from aromatics.