Molecular sieve

Molecular sieve, also known as zeolite, is a porous material capable of selectively adsorbing molecules of a certain size. This substance is often used as a desiccant and for the adsorption of gases in various industrial applications.

Porous structure

Molecular sieves have a large inner surface area as they consist of a grid of micropores. The size of the pores varies depending on the type of molecular sieve. There are different types of molecular sieves with different pore sizes and specific applications.

Selective adsorption

Due to their micropores, molecular sieves can selectively adsorb certain molecules while allowing others to pass through. This means that only molecules with a smaller diameter than the micropores of the molecular sieve can enter the pores. This makes them useful for applications such as the dehumidification of air and gases.

Air drying

Molecular sieves are often used in desiccant products to dehumidify air or gases. They adsorb water from the air and hold it in their pores.

Molecular sieves with a high water absorption capacity are used to dehumidify air inside pharmaceutical packaging or other sensitive products that need to be protected from moisture. Typically, the molecular sieve zeolite A with a pore size of 3 or 4 angstroms is used.

Zeolite 3A (type 3A molecular sieve)

This zeolite has a pore size of 3 angstroms (A) = 0.3 nm, which makes it particularly suitable for adsorbing water molecules. This pore size is too small for solvents to be adsorbed. Zeolite 3A is often used to remove water from air or gases, especially when it comes to protecting sensitive products such as medicines.

Zeolite 4A (type 4A molecular sieve)

Similar to zeolite 3A, zeolite 4A also has a high affinity for water molecules. It is also often used in desiccant products to adsorb moisture from the air and thus protect sensitive goods.

These types of molecular sieves are produced in the form of beads or granules and packaged in bags or canisters or compressed in tablet form. These are then added to pharmaceutical or nutraceutical products in their packaging. The process of adsorption enables these molecular sieves to bind the water and thus dehumidify the air in the packaging. This improves the stability and durability of the products to be protected.

Difference to silica gel

Molecular sieves bind water molecules regardless of the ambient humidity, i.e. even below 10% relative humidity. However, they have a lower absorption capacity than silica gel. It is used for particularly sharp drying or to protect products at the lowest possible relative humidity of close to 0% inside the packaging.

In contrast to silica gel, molecular sieve as a desiccant has a higher specific adsorption capacity for water molecules. This means that molecular sieves can absorb more water per unit weight. Molecular sieves also have a precisely defined pore size, which makes it possible to selectively adsorb molecules. And, compared to silica gel, they already start to absorb moisture from the ambient air at lower relative humidity. Molecular sieve is the desiccant of choice for very high demands on the type and function of air dehumidification.