What Are Molecular Sieve Beads and How They Work?

• Posted on 31 May 2024
• 0

Discover everything there is to know about molecular sieves. What they are, how they work, and how they can help absorb moisture and maintain product quality.

Molecular sieves are commonly used to remove specific molecular compounds based on their pore diameter. Essential in various industrial processes in the petrochemical industry, pharmaceutical, air separation, gas purification, food and beverage, environmental, automotive, electronics, and energy storage and conversion to selectively adsorb, separate, and purify gases. Sieve beads are a great solution to maintain product quality against detrimental factors such as moisture.

Each type of molecular sieve is divided into its own pore size and application. A molecular sieve is made of crystalline aluminosilicate that has a uniform pore size and structure to create a crystalline lattice. Pore diameters are often expressed as a number of nanometers.

The microporous structures have pores with diameters less than 2 nm, and while macro-porous structures have diameters greater than 50 nm, the mesoporous category covers the middle ground with pore diameters between 2 and 50 nm. The different size holes determine the molecules adsorbed.

The different pore sizes are created by swapping out cations (positive ions) in the chemical makeup of the crystalline structure. This creates larger or smaller pores in a very organized crystalline structure, which allows small molecules to pass by while adsorbing larger molecules through an ion exchange. This is how a molecular sieve is used as a universal drying agent to remove specific compounds from a solution as long as the molecules critical diameter matches the tiny pores of the molecular sieve.

3A Molecular Sieve

Molecular sieves sized 3A have a bulk density between 0.6 and 0.68 g/ml with a pore size of 3 angstroms which allows smaller molecules to pass through. Used heavily in the oil and petroleum industries to purify petroleum gas. Using the high adsorbent properties of sieve beads, this size of desiccant is commonly used to absorb water molecules and remove them from oils. Can also be used to remove moisture from the air, ethanol, and insulated glass. 

The 3A molecular sieve size has a fast adsorption rate, resistance to crushing and pollution, and can be reused after being regenerated.

4A Molecular Sieve

Molecular sieve classified as 4A have pore diameters close to 4 Angstroms, which allow large molecules to pass through. Commonly used to separate water molecules, carbon dioxide, and sulfur compounds in petroleum and chemical industries where contaminants need to be efficiently removed without the use of another medium or process. Such as re-proofing alcohol by removing water content and thus raising the alcohol percentage. Very high in adsorption capacity, these beads can be used multiple times to selectively remove a specific compound. 

Sieve Beads for the Cannabis Industry - 10A (13x) Sieve 

In recent years, the cannabis industry has become a top consumer of Molecular Sieve beads for cannabis oil extraction purposes. When performing an extraction using a hydrocarbon solvent such as butane or propane, the hydrocarbon gas will pick up quite a bit of water as it douses the plant material. As water builds up in the hydrocarbon gas, issues begin to build up as well. Hydrocarbon gas is often chilled in this process, and if there are significant amounts of water in the gas, the water will freeze and clog up important hoses. Also, the solvent loses its effectiveness and water can contaminate end products if not removed.

This is where the molecular sieve beads come in handy. Inside these closed machines, there will be a filtration section that consists of bulk sieve beads, usually 10A (13X) sieve beads. The filtration section uses the sieve beads to capture moisture, while the hydrocarbon gasses continue to pass right by. By performing a simple filtration of hydrocarbon gas, operators are able to save time from preventing clogs or contamination to final products.

How Much Water Can Molecular Sieve Beads Hold?

Factors such as temperature, humidity, and pore size decide how much water any given sieve beads can hold. A general rule of thumb is that sieve beads will adsorb a little more than 20% of their weight in water. 

How to Store Molecular Sieve Beads

Sieve beads are best stored in metal containers away from any source of heat or humidity. Temperatures should be around 60°F to 80°F with humidity levels between 0 and 70%.

How to Choose the Right Molecular Sieve Beads

Consider the type of molecule you would like adsorbed, purity of your end product, and operating conditions. Select a sieve with slightly larger pores than the molecule yo are aiming to remove, this will better allow the contaminate to be adsorbed without causing any blocking. Make sure operating temperatures are ideal for your sieve, some sieves are better for cold and others are not.

Goldleaf can help select the correct sieve beads if you are not sure which you need. Call or email any time and we would be happy to assist. 

For any additional questions or inquiries please feel free to reach out to Goldeaf directly.

Phone: (510)487-1390

Email: [email protected]