Character: 
Molecular sieves are a class of adsorbents composed of crystalline silicates—such as sodium aluminosilicate and calcium aluminosilicate—and are inorganic porous solid materials with a uniform microporous structure. They appear as yellow-brown granules and are available in spherical and rod‑shaped forms. 
Common Specifications and Applications: 
(1) 3A molecular sieve is an alkali metal aluminosilicate with a pore size of 3 angstroms (0.3 nanometers), prepared by ion exchange with potassium ions. 
Due to its abundant 3-angstrom crystal adsorption cavities, it does not adsorb any molecules larger than 3 angstroms in diameter, exhibits strong preferential adsorption for water molecules, and achieves extremely high water‑removal accuracy. Consequently, it is widely used in the chemical industry as an adsorbent for drying gases and liquids.

Specific applications: 
Adsorption-based separation of unsaturated hydrocarbons and pyrolysis gases: ethylene, acetylene, propylene, butadiene, and others. Deep dehydration and drying of various gases and liquids: such as air, ethanol, natural gas, methane, and more. 
(2) 4A molecular sieve is an alkali metal aluminosilicate with a pore size of 4 angstroms (0.4 nanometers) and is a sodium-containing Type A molecular sieve. 
Due to its internal structure, which features numerous 4-angstrom crystal adsorption cavities, it selectively adsorbs only substances with molecular diameters smaller than 4 angstroms, while excluding any molecules larger than 4 angstroms. Moreover, it exhibits a strong preferential affinity for water molecules, making it widely used as an adsorbent and desiccant for various gases and liquids, maintaining exceptionally high adsorption accuracy even under trace‑water conditions.

Specific applications: Molecular sieve desiccants are commonly used in drying equipment such as air compressors and liquefied gas stations; they adsorb water, methanol, ethanol, hydrogen sulfide, sulfur dioxide, carbon dioxide, ethylene, and propylene, but do not adsorb propane; they are employed for the deep drying of gases and liquids including air, natural gas, alkanes, and refrigerants; they provide static drying for pharmaceutical packaging, electronic components, and perishable materials; and they serve as dehydrating agents in paints, dyes, and coatings. 
(3) 5A molecular sieve is an alkali metal aluminosilicate with a pore size of 5 angstroms (0.5 nanometers), produced by ion exchange with calcium ions. 
Due to its internal structure, which features numerous crystalline adsorption cavities with a diameter of 5 Å, it does not adsorb any molecules whose diameters exceed 5 Å. It is primarily used for the separation of normal and isomeric hydrocarbons, pressure swing adsorption, and the co-adsorption of water and carbon dioxide. 
Specific applications: 
Drying, purification, and upgrading of various gaseous streams; adsorption‑based separation of normal and isomeric hydrocarbons; drying, desulfurization, and impurity removal from natural gas, as well as the adsorption of carbon dioxide and water; and adsorptive purification of off‑gas streams containing ammonia and nitrogen. 
(4) 13X molecular sieve is an alkali metal aluminosilicate with a pore size of 10 Å (1 nm); it is a sodium‑ion‑exchanged X‑type molecular sieve. 
Due to its internal structure featuring numerous crystalline adsorption cavities measuring 10 angstroms in diameter, it can adsorb molecules with diameters smaller than 10 angstroms while excluding any molecules larger than 10 angstroms. It is suitable for use as a catalyst support and for the co-adsorption of water and carbon dioxide, as well as water and hydrogen sulfide gas, and for purifying natural gas by removing impurities and odors. Its primary applications are in the pharmaceutical industry. 
Drying with an air compression system offers greater adsorption capacity and a lower dew point. 
Specific applications: 
Deep purification of feed gas in air separation units (simultaneously removing carbon dioxide, water, and a portion of hydrocarbons); drying and desulfurization of natural gas, liquefied petroleum gas, and liquid hydrocarbons; deep drying of general industrial gases; adsorption-based odor removal from industrial exhaust gases.