What is Molecular Sieve?
Molecular sieves are synthetic crystalline aluminosilicates (zeolites) with precisely uniform pore sizes ranging from 3 to 10 angstroms. Unlike silica gel or activated alumina, molecular sieves have a fixed pore aperture that allows them to selectively adsorb molecules smaller than the pore size while excluding larger ones.
Four Standard Grades
3A Molecular Sieve (Potassium Form, 3Å pore)
3A sieves have a pore diameter of 3 angstroms and are produced by ion-exchanging 4A sieves with potassium. They adsorb water but exclude molecules larger than 3Å, making them ideal for drying unsaturated hydrocarbons (ethylene, propylene, butadiene) and polar liquids (ethanol, methanol).
- Drying of cracked gas (C2, C3, C4 fractions)
- Dehydration of ethanol to absolute grade (200 proof)
- Polyolefin production — water removal from ethylene/propylene feed
- Refrigerant drying (R12, R22, R134a)
- Natural gas dehydration at low pressure
4A Molecular Sieve (Sodium Form, 4Å pore)
4A is the most widely used grade, with 4 angstrom pores that adsorb water, CO₂, and small polar molecules. It's the universal desiccant for natural gas, air separation, and general industrial gas drying.
- Natural gas dehydration to pipeline spec (<1 lb/MMSCF)
- PSA oxygen/nitrogen generation — pre-drying feed air
- Compressed air drying to -40°C pressure dew point
- Air conditioning refrigerant and adsorbent
- Pharmaceutical packaging as desiccant
5A Molecular Sieve (Calcium Form, 5Å pore)
5A sieves have 5 angstrom pores that adsorb normal paraffins (n-alkanes) while excluding iso-paraffins and aromatics. Primary application is paraffin separation in petrochemical refining.
- n-/iso-paraffin separation in refinery streams
- Hydrogen purification via PSA
- Oxygen production from air (alternative to 13X)
13X Molecular Sieve (Sodium Form, 10Å pore)
13X has the largest pore size (10 angstroms) and is used for bulk removal of water, CO₂, and H₂S from gas streams. It's the standard for air separation units and natural gas sweetening.
- Air separation units (ASU) — front-end purification
- Natural gas sweetening — CO₂ and H₂S removal
- LPG purification — removal of sulfur compounds
- Catalyst protection in downstream processes
Typical Technical Specifications
| Parameter | 3A | 4A | 5A | 13X |
|---|---|---|---|---|
| Pore Size (Å) | 3 | 4 | 5 | 10 |
| Bulk Density (g/ml) | ≥0.65 | ≥0.65 | ≥0.65 | ≥0.62 |
| Crush Strength (N/颗) | ≥30 | ≥30 | ≥30 | ≥30 |
| Water Adsorption (%) | ≥20 | ≥22 | ≥22 | ≥28 |
| Wear Rate (wt%) | ≤0.2 | ≤0.2 | ≤0.2 | ≤0.2 |
| Particle Size (mm) | 1.6-2.5 / 3-5 | 1.6-2.5 / 3-5 | 1.6-2.5 / 3-5 | 1.6-2.5 / 3-5 |
Packaging & Delivery
- Standard: 25 kg kraft paper bags with PE inner liner
- Bulk: 500 kg / 1000 kg jumbo bags for large orders
- Sealed steel drums available for moisture-sensitive shipments
- Lead time: 7-15 days for stock specifications, 15-25 days for custom
- Documents: COA, MSDS, ISO 9001 certificate, commercial invoice
How to Order
Tell us your application, required pore size, particle size preference, and monthly quantity. Our engineers will recommend the right grade and provide a competitive quotation within 2 hours.