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Molecular Sieves

Molecular sieve adsorbents are crystalline aluminosilicates, known as zeolites. Their unique structure allows the water of crystallization to be removed, leaving a porous crystalline structure. These pores, or cages, have a high affinity to re-adsorb water or other polar molecules. Aided by strong ionic forces (electrostatic fields) due to the presence of cations such as sodium, calcium and potassium, and by the enormous internal surface area of up to 1,000 m2/g, molecular sieves will adsorb a considerable amount of water or other fluids. If the fluid to be adsorbed is a polar compound, it can be adsorbed with high loading, even at very low concentrations of the fluid. Molecular sieves will, therefore, remove gas or liquid impurities to very low levels (ppm or less).

Another feature of molecular sieve adsorbents is their ability to separate gases or liquids by molecular size or polarity. The pore, or cage, openings are the same size as many molecules, e.g., in the case of hydrocarbon paraffins, straight-chained molecules can fit into the pores and be adsorbed, while the branched-chain molecules cannot enter the pores and pass through the molecular sieve bed unadsorbed.

Research and Development

Since its founding, Zeochem has been at the leading edge of synthetic molecular sieve technology. We have developed an ultra-stable molecular sieve able to withstand thousands of thermal regenerations with delayed decay and exceptional capacity retention. Our efforts have been rewarded in recent years with numerous patents on zeolite manufacture and applications. These examples of unilateral product and process development are mirrored by our focus on real-world applications and participation in joint development projects with customers. Well-equipped laboratories and pilot facilities support our researchers, who also have close relationships with numerous universities and private laboratories, with their specialized facilities and expertise.

Manufacturing

Zeochem’s proprietary manufacturing processes use the latest processing equipment and computerized process control systems. Special efforts have been made to monitor and control all phases of production. Vendors are required to not only meet our stringent raw material specifications, but also to have in place extensive quality systems geared toward the continuous improvement of their products and processes. We demand that of ourselves and require it of our suppliers. We continue to upgrade and expand our processes and manufacturing capabilities, including toll manufacturing, regeneration of spent product and custom manufacturing. This continuous improvement allows us to meet the challenges of the 21st century.

Download our Molecular Sieves Brochure here.

Consistent. Responsive. Innovative.

Custom Solutions

Zeochem’s technical service engineers and scientists have decades of experience in design, operation, optimization and overall maintenance of molecular sieve units.

From the start, our technical service engineers provide conceptual advice and design support for your project. As the project moves forward, we can be called upon to review detailed designs and answer any questions regarding our products and their use in your operation. Even after the project is completed, our team supports you with consultation on last-minute change orders and start-up assistance when the unit is commissioned. After-sale service is available for troubleshooting and performance optimization.

  • 3A
  • 4A
  • 5A
  • 13X
  • Calcium X
  • Lithium X
  • Purmol Zeolite Powder
  • Activated Alumina

3A

The 3A molecular sieve is an alkali metal aluminosilicate with a pore opening of approximately 3 angstroms. Type 3A is made by ion-exchanging the sodium in the type 4A sieve with potassium. The 3A molecular sieve will exclude most molecules except water, making it very selective. This type of bead also has advantages in crush strength, durability and high rate of adsorption. The 3A molecular sieve can remove moisture in both liquid and gas applications. Type 3A is used in the production of insulated glass, refrigerant drying, general moisture removal and the drying of natural gas, hydrocarbon liquids, ethanol and reactive monomers such as olefins.

4A

The 4A molecular sieve is an alkali metal aluminosilicate with an effective pore opening of approximately 4 angstroms. The sodium form of type A is widely used as a general-purpose drying agent and has good physical and adsorption properties. Type 4A beads can be used to adsorb water, ammonia, methanol, ethanol and carbon dioxide. This type of molecular sieve is often used to remove moisture from gas and liquid streams, where co-adsorption of sulfur compounds and carbon dioxide is not a concern.

5A

The 5A molecular sieve is an alkali metal aluminosilicate with an effective pore opening of 5 angstroms and is the calcium-exchanged form of the type A zeolite. The strong ionic forces of the divalent calcium cation make 5A an excellent choice for removing carbon dioxide, carbon monoxide, alcohols and other oxygenates, hydrogen sulfide, methyl and ethyl mercaptans, and other polar molecules. This product is also effective for the bulk separation of normal and iso-paraffin hydrocarbons. This type of molecular sieve has a high rate of adsorption and desorption, a higher rate of contamination resistance and a high crush strength.

13X

The 13X molecular sieve is the sodium form of zeolite X and has a much larger pore opening than the type A crystals, with an effective pore diameter of 10 angstroms. It also has the highest theoretical capacity of the common adsorbents and excellent mass transfer rates. Type 13X offers enhanced adsorption performance over the type A zeolite, and it can remove impurities too large to fit into the type A zeolite crystal cages. It is also often used to separate nitrogen from the air to produce a high-purity oxygen stream. Our 13X materials are physically robust and have high adsorption capacity for water, alcohols and other oxygenates, sulfur compounds and carbon dioxide.

Calcium X

Calcium X (CaX) and Calcium LSX (CaLSX) are the calcium-exchanged forms of the 13X and LSX type zeolites. These molecular sieves have various applications throughout the process industry.

In the production of industrial oxygen, CaX and CaLSX sieves are used for direct oxygen concentration in VPSA oxygen plants. In addition, adsorbents are used in the front-end purification section of cryogenic oxygen plants to remove NOx and lighter hydrocarbons from the inlet air.

In the manufacturing of industrial hydrogen, CaX and CaLSX sieves are used as one of the adsorbent layers in hydrogen pressure swing adsorption (PSA) plants, typically for CO adsorption.

CaX sieves have also been used in niche applications in the purification of CO2 for food applications.

Zeochem has an extensive portfolio of CaX and CaLSX type molecular sieves, each specifically designed to provide maximum performance in its specific applications.

Lithium X

Zeochem's line of lithium molecular sieves offers proven performance, as exhibited by the millions of pounds used in air separation across the globe. We use our patented technology to create a portfolio of lithium molecular sieves for both industrial gas and medical oxygen applications. Our products have exceptional nitrogen capacity, extraordinary kinetics and superior selectivity to yield high-purity oxygen streams from the air. The patented binding system provides unrivaled physical characteristics, such as outstanding mechanical strength and durability.

Zeochem industrial gas molecular sieves have a proven track record with thousands of tons installed in vacuum pressure swing adsorption (VPSA) oxygen processes across the globe. Due to their superior selectivity, greater capacity and faster kinetics, one can achieve a high oxygen purity with lower power requirements and a smaller VPSA footprint.

Zeochem medical oxygen molecular sieves allow customers to produce oxygen-rich streams with purity exceeding 95% in stationary and portable oxygen concentrators (POCs). Our patented binding technologies offer a molecular sieve with lower density while exceeding expectations for capacity, selectivity, kinetics and mechanical durability.

Zeochem's line of lithium molecular sieves encompasses the perfect balance of capacity, selectivity, kinetics and physical strength. Rather than singularly focusing on capacity, this unique approach allows us to manufacture a portfolio of lithium materials that excels in medical oxygen and industrial gas VPSA applications.

Purmol Zeolite Powder

Purmol molecular sieve zeolite powder is an excellent moisture scavenger for polyurethane coatings, adhesives, sealants and elastomers. Purmol adsorbents are synthetic zeolites in powder form with a complex alkali aluminosilicate structure. This structure is very open and contains pores of a regular and precisely defined size. This allows Purmol powder to adsorb molecules selectively based on molecular size and polarity. In practice, Purmol powder adsorbs water, but not solvents, resins or pigments.

Purmol molecular sieve zeolite powder has a wide variety of applications. While many current applications are based on polyurethane and other plastics, it can be used in numerous formulations where selective adsorption of small polar molecules is required within a liquid or solid medium. The fine particle size of Purmol powder ensures intimate mixing and excellent dispersion.

3A Purmol Powder

Potassium (K) form of the type A zeolite with a pore size of 3 angstroms. Recommended for use where co-adsorption of molecules other than water may be of concern.

4A Purmol Powder

Sodium (Na) form of the type A zeolite with a pore size of 4 angstroms. Combines high adsorption capacity for water and is characterized by a lower pH value.

5A Purmol Powder

Calcium (Ca) form of the type A zeolite with a pore size of 5 angstroms, allowing for adsorption of larger molecules with a critical diameter of less than 5 angstroms.

3A Purmol Paste

A 50%-by-weight dispersion of 3A Purmol powder in castor oil. Recommended for polyurethane systems where a faster incorporation of the Purmol powder is desired.

Activated Alumina

Activated alumina adsorbent is used as a protective layer, at the inlet of many gas-phase molecular sieve beds. Activated alumina has an exceptionally high volumetric capacity for any liquids that may be present in the feed stream and can hold over 50% of its weight in liquids. It serves to protect the molecular sieve bed from film coating and accelerated coking as a result of hydrocarbon condensates and carryover, potential amine and glycol carryover from upstream processes, and liquid water entrainment.

In addition, activated alumina is a dehydration-grade material with high density that can remove water when not being used for liquids containment. It regenerates more easily than a molecular sieve and thus adds little additional load to the regeneration step in thermal swing applications. Thus, it can be easily added in most applications with minimal changes and will typically require no more than 1 ft. (0.3 meters) of additional bed height.

Additionally, it can be used in the drying of streams such as air, carbon dioxide, carbon monoxide, sulfur hexafluoride, ammonia, hydrogen sulfide, heavy hydrocarbons, gasoline, chlorinated or fluorinated hydrocarbons, or aromatic hydrocarbons. It is most often recommended when complete dryness is not necessary (ppm level water is acceptable) and where high thermal and mechanical resistance is required.

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