Molecular sieves, as highly efficient adsorbents and catalysts, play a critical role in industries such as petrochemicals, gas separation, and medical oxygen production. Different types of molecular sieves, with their unique pore sizes and chemical properties, are tailored for various industrial applications. This article provides a detailed introduction to 3A, 4A, 5A, 13X (including 13X HP and 13X APG), and lithium molecular sieves, covering their definitions, characteristics, applications, and key parameters to help readers fully understand the exceptional performance of these "industrial sieves."
Molecular sieves are crystalline aluminosilicates with uniform microporous structures that selectively adsorb molecules based on size and polarity. Their general chemical formula is:
Mx/n[(AlO2)x(SiO2)y]⋅mH2O
where M represents cations (e.g., Na⁺, K⁺, Ca²⁺), n is the cation valence, and x/y determines the pore size.
3A Molecular Sieve
Potassium ion (K⁺)-exchanged Type A molecular sieve with a pore size of ~3 Å (0.3 nm).
Features:
Adsorbs only water molecules (2.8 Å diameter), excluding larger molecules (e.g., ethylene, propane).
High mechanical strength and strong resistance to contamination.
Applications:
- Deep drying of ethanol and liquefied petroleum gas.
- Dehydration of refrigerants.
- Moisture prevention in plastics.
4A Molecular Sieve:
Sodium ion (Na⁺)-based Type A molecular sieve with a pore size of 4 Å (0.4 nm).
Features:
Adsorbs small molecules such as water, methanol, ethanol, and CO₂.Widely used in industrial and consumer drying applications.
Applications:
- Dehumidification in compressed air systems.
- Moisture protection for pharmaceuticals and electronic components.
- Detergent builder (water softening).
5A Molecular Sieve
Calcium ion (Ca²⁺)-exchanged Type A molecular sieve with a pore size of 5 Å (0.5 nm).
Features:
- Adsorbs linear alkanes (e.g., C₃H₈, n-C₄H₁₀) but excludes branched hydrocarbons.
- Used for isomer separation in petroleum refining.
Applications: - Petroleum dewaxing (improving diesel cold flow properties).
- Oxygen-nitrogen separation (PSA oxygen generation).
- Natural gas desulfurization (removal of H₂S and CO₂).
13X Molecular Sieve
Sodium-type X molecular sieve with a pore size of 10 Å (1.0 nm) and high surface area.
Features:
Exceptional adsorption capacity for large molecules (e.g., aromatics, hydrogen sulfide).
Widely used in gas purification and separation.
Applications:
Air separation (oxygen/nitrogen production).
Natural gas drying and decarbonization (CO₂ removal).
Industrial waste gas treatment (VOCs adsorption).
13X HP (High Performance)
Definition: Optimized 13X molecular sieve with higher adsorption capacity and crush strength.
Features:
- 15–20% higher adsorption capacity than standard 13X.
- Suitable for high-pressure and high-humidity environments.
Applications: - Cryogenic air separation units.
- High-purity gas production (e.g., electronic-grade nitrogen).
13X APG (Aviation Grade)
Aviation-optimized 13X molecular sieve with low dust and high stability.
Features:
Complies with aviation standards (e.g., MIL-D-3464E).
Resistant to gas flow erosion, long service life.
Applications:
Aircraft air circulation systems (cabin oxygen generation).
Spacecraft gas purification.
Lithium Molecular Sieve (Li-LSX)
Lithium ion (Li⁺)-exchanged X-type molecular sieve with a pore size of ~9 Å.
Features:
- Strong selectivity for nitrogen (N₂) adsorption, enabling efficient oxygen-nitrogen separation.
- Used for high-efficiency oxygen production.
- Applications:
- Medical oxygen concentrators (>90% O₂ purity).
- Oxygen-enriched combustion in blast furnaces.
- Life support systems in submarines and spacecraft.
| Type | Pore size | Cation Type | Main Adsorbed Molecules | Application |
| 3X | 3 | K⁺ | H₂O | Ethanol dehydration, LPG drying |
| 4X | 4 | Na⁺ | H₂O, CO₂, CH₃OH | Air drying, detergents |
| 5X | 5 | Ca²⁺ | n-alkanes, H₂S | Petroleum dewaxing, PSA O₂ |
| 13X | 10 | Na⁺ | CO₂, H₂S, aromatics | Natural gas purification, air separation |
| 13X HP | 10 | Na⁺ (optimized) | Large gas molecules | High-purity gas production |
| 13X APG | 10 | Na⁺ (low dust) | Aviation gas purification | Aircraft oxygen systems |
| Li-LSX | 9 | Li⁺ | N₂ (preferential) | Medical oxygen concentrators |
Post time: Apr-03-2025