A molecular sieve is the most effective option for removing water from liquids and gases. Though older products such as silica gel and alumina desiccants have traditionally been used for such purposes, molecular sieve desiccants can get the job done with purer results.
Molecular sieves are uniform pore crystalline structure. Molecular sieves operate on the size exclusion principle. Smaller molecules that fit into the pores are adsorbed while larger molecules pass through. Molecular sieves have regular pore openings of 3, 4, 5, or 10 Angstroms. Polarity of the molecules matter because the highly polarized molecules are adsorbed more readily into the pores than non-polar molecules. Molecules are selectively removed in this manner
 When a gas or liquid is passed through the mole sieve, smaller pieces are adsorbed while larger molecules pass through. Unlike other filters, the adsorbed substance is then trapped. Therefore, when water is used in the sieve, penetrating water molecules are caught and retained in the pores, leaving the remaining liquid substantially cleared of the water molecules.
In all, a mole sieve adsorbs up to 22% of its own weight in water. More than that, these sieves are exceptionally versatile, with adsorption possible based on molecular size, molecular affinity for the sieve crystal surface, or even the shape of the molecule. For these reasons, molecular sieve desiccants can produce gases or liquids that are virtually water free..

 

 

Types of Molecular Sieves

 

3A	Used for insulated glass to prevent fogging and deflection of dual pane windows. Olefin drying and natural gas. Powders are used in formulations with polyurethanes and insulated glass swiggle strips.
4A	Dessicant for drying of gases, air, natural gas and hydrocarbon liquids. 4A will adsorb carbon dioxide.
5A	Dehydration and the removal of CO2 and H2S from natural gas units. Used in Isosiv units and Pressure Swing Adsorption for Hydrogen. Powders are used in some formulations.
13X	Air prepurification to remove water and CO2. 13X removes various polar molecules from olefinic and light hydrocarbons streams.

3A molecular sieve has a pore size of 3A or 3 angstrom. Any molecule larger than 3A will not be able to be adsorbed. Mole Sieve is an alkali metal alumino-silicate, the potassium form of the type A crystal structure. 3 Angstrom is created when part of the sodium ions of the 4 Angstrom sieve are replaced by potassium ions. The sequence rate of adsorption rate is helium, neon, nitrogen and water.
The advantages of our 3A mole sieve are consistently high adsorption speed, and higher contamination resistance, stronger crushing strength, increasing cyclic times which provide an extended product life. 3A Molecular Sieve is primarily for removing moisture from liquefied and gaseous materials.
All these advantages have made it come to be the most essential and necessary desiccant in the fields of the deep drying, refinery, polymerization for cracked gases, ethylene, propylene and any other non-acidic gases or liquids in petroleum and chemical industrials.

 

The various specifications of Molecular Sieves are:

• Form: Sphere (Balls) / Cylindrical Pellets
• Size: 1.5 - 3.5 mm. dia. / 1.5mm - 3.0 mm dia
• Bulk Density: 0.55 to 0.68 Kg/Liter
• Surface Area: 345 to 415 M2/Gm.
• Pore Volume: 0.40 to 0.50 CC/Gm.
• Adsorption Capacity (at 75 % RH) : 23-27 %.
• Attrition Loss: 0.02 -0.2 %.

It has become one of the most reliable desiccants for a variety of applications including:

• Refrigerant Drying
• Moisture removal in PU Plastic or Paint
• Natural Gas Drying
• Drying Cracked Gas
• Static drying of insulating glass units, whether air filled or gas-filled.
• Dehydration of highly polar compounds, such as methanol and ethanol.
• Dehydration of unsaturated hydrocarbons (e.g. ethylene, propylene, butadien).
• Sweetening of Natural Gas

 

4A molecular sieve has a pore size of 4A or 4 angstrom. Any molecule larger than 4A will not be able to be adsorbed.  4 Angstroms are the sodium forms of the Type A crystal structure. It is mainly used to absorb water, methanol, ethanol, sulfureted hydrogen, carbon dioxide, ethylene, propylene
The advantages of our high quality 4A mole sieve are consistent adsorption speed, and higher contamination resistance, stronger crushing increasing cyclic times which provide an extended product life. 4A Molecular Sieve is primarily for removing moisture from liquefied and gaseous materials.
The various specifications of Molecular Sieves are: 

• Form: Sphere (Balls) / Cylindrical Pellets
• Size: 1.5 - 3.5 mm. dia. / 1.5mm - 3.0 mm dia
• Bulk Density: 0.55 to 0.68 Kg/Liter
• Surface Area: 345 to 415 M2/Gm.
• Pore Volume: 0.40 to 0.50 CC/Gm.
• Adsorption Capacity (at 75 % RH) : 23-27 %.
• Attrition Loss: 0.02 -0.2 %.

It has become one of the most reliable desiccants for a variety of applications including:

• Drying of air, Natural gas, alkane and refrigerant.
• Moisture removal in PU Plastic or Paint
• Natural Gas Drying
• Drying Cracked Gas
• Static drying of insulating glass units, whether air filled or gas-filled.
• Dehydration of highly polar compounds, such as methanol and ethanol.
• Dehydration of unsaturated hydrocarbons (e.g. ethylene, propylene, butadien).
• Generation and purification of argon.
• Type 4A molecular sieve is typically used in regenerable drying systems to remove water vapor or contaminants which have a smaller critical diameter than four angstroms

 

5A Molecular Sieve type has a pore size that is 5A. It cannot adsords any molecules smaller than 5A.  This molecular sieve is an alkali alumino silicate in the calcium form of Type A crystal structure. The basic application is separation of the normal and isomerous alkane, co-adsorption of carbon dioxide and moisture, along with pressure swing adsorption (PSA) for gases
Applications :

• It is the most reliable desiccant for several applications including
• Removel of water and carbon dioxide from air.  
• Normal paraffin separating process 
• Refining SF6 refrigerant for power (removing moisture and hydrocarbon)
• Oxygen/hydrogen PSA (Pressure Swing Adsorption) process

13X Molecular Sieve has a pore size of roughly 10A. This is considerably larger than any of the A type openings. This desiccant is used primarily for refinements of liquid and gases because it offers synchronized absorption for bi-molecule and tri-molecule. It can co-adsorb CO2 and H2O, H2O and H2S. 13X Mole sieve also has applications as a desiccant for medical and compressor uses and as a c catalyze carrier.
Applications:
It has become one of the most reliable desiccants for a variety of applications including:

• Type 13X is used commercially for general gas drying, air plant feed purification (simultaneous removal of H20 and CO2) and liquid hydrocarbon and natural gas sweetening (H2S and mercapstan removal).
• All molecules which can be adsorbed on molecular sieves 3A, 4A and 5A can be adsorbed on Type 13X. In addition, Type 13X can adsorb molecules of larger critical diameters, such as aromatics and branched-chain hydrocarbons.
• Removal of grease and solvents.