A molecular sieve is a highly porous, synthetically produced adsorbent—usually made of zeolite—that can filter out specific molecules from gas or liquid mixtures based on their size and polarity. The special property of molecular sieves is their defined pore size, typically between 3 and 10 angstroms (Å), which corresponds to approximately 0.3 to 1 nanometer. This makes them act like a microscopic sieve, allowing only certain molecules to enter their pores while excluding larger molecules.

The water absorption of molecular sieves depends on the type, grain size, and ambient conditions. Our products can adsorb up to 24% of their own weight in water in a fully saturated environment. This means that 1 kg of molecular sieve can absorb up to 240 g of water vapor, depending on the operating conditions.

Types 3A, 4A, and 13X are particularly efficient, having been specifically developed for the adsorption of water molecules. While Type 3A is primarily used for moisture removal in the presence of other gases (e.g., for drying unsaturated hydrocarbons), Type 4A is characterized by its high adsorption capacity for water vapor in the air or for technical gases. The actual water absorption depends on the relative humidity, temperature, pressure, and cycle duration during operation.

Molecular sieve types 3A, 4A, 5A, and 13X differ primarily in their pore size and thus in their selectivity for the specific molecules they can adsorb. Type 3A has the smallest pore structure (approx. 3 angstroms) and adsorbs only water molecules—ideal for moisture removal without affecting other substances such as ethylene. Molecular sieve 4A (approx. 4 Å) is more versatile and, in addition to water, also binds smaller molecules such as ammonia, CO₂, or methanol. It is particularly well-suited for air and gas drying. Type 5A (approx. 5 Å) can also adsorb n-alkanes and linear hydrocarbons, making it ideal for molecular separations and applications such as natural gas or hydrogen processing. Molecular sieve 13X has the largest pores at approximately 10 Å and can adsorb even larger molecules such as aromatics, sulfur compounds, or CO₂. It offers the highest adsorption capacity and is frequently used in air purification and biogas upgrading.

The choice of the right molecular sieve ultimately depends on the desired target substance, operating conditions, and application. While Type 3A is optimal for pure moisture removal, Types 5A and 13X offer more advanced capabilities for selective molecular separation and gas conditioning. For a detailed overview, we have provided a separate table:

Adsorbierbarkeit versch. Stoffe an Molekularsieben

No, unlike silica gel, our molecular sieves do not have a color indicator.

Molecular sieves can be fully regenerated after being saturated with moisture or other adsorbed molecules. This is one of their greatest advantages over other desiccants such as silica gel or activated carbon. Regeneration occurs through the application of heat (thermal regeneration).

The molecular sieve is heated to 300°C to release the adsorbed molecules – usually water vapor – from the pore system. This process is fully reversible because molecular sieves have a very stable crystalline structure and their adsorption capacity is retained even over many cycles. However, since the binding forces in the crystal structure are so strong that water molecules are only released at these temperatures, the possibility of self-regeneration is eliminated. This means that flushing out the bound water with the dried supply air during the cyclic respiration of a system or container is effectively impossible without the addition of heat.

The pore size of the different types of molecular sieves determines which molecules can penetrate the sieve and be adsorbed – a principle known as molecular sieving. The smaller the pores, the more selective the adsorption; the larger the pores, the more molecules can be adsorbed. This allows molecular sieves to be precisely tailored to the respective application – whether for pure air drying, gas purification, or selective molecular separation.

Adsorbierbarkeit versch. Stoffe an Molekularsieben

Yes, our molecular sieves can selectively adsorb specific gases such as CO₂, H₂S, or NH₃, depending on the selected sieve type and the process conditions. Selective gas filtration is one of the greatest strengths of molecular sieves – it is based on precisely defined pore size, molecular structure, and polarity. Highly polar or easily polarizable gases such as carbon dioxide (CO₂), hydrogen sulfide (H₂S), and ammonia (NH₃) have a high affinity for the zeolite structure of the molecular sieves and are bound particularly efficiently.

Molecular sieves are therefore extremely efficient at filtering certain gases due to their high selectivity. They are based on physical adsorption principles without chemical reactions and offer the possibility of reuse through regeneration. Furthermore, they are particularly well suited for continuous operation in industrial plants.

Molecular sieves are extremely hygroscopic—meaning they attract moisture from the ambient air. Proper storage is essential to maintain their adsorption capacity. Even small amounts of humidity can unintentionally clog the pores of the sieves, thereby impairing or completely blocking their effectiveness. Store in a dry place, observe the packaging, and observe temperature control and storage conditions.

Should unwanted moisture ingress occur, molecular sieves can be fully reactivated through thermal regeneration.

The use of molecular sieves for air drying offers decisive advantages in efficiency, reliability, and drying performance over conventional drying methods such as refrigeration or adsorption dryers using silica gel. With a pore diameter of only 0.4 nm, they possess a high internal surface area of up to 1000 m². Molecular sieves – also known as zeolites – are synthetically produced aluminosilicates with a highly porous, crystalline structure specifically designed for the adsorption of water molecules.

Advantages of air drying:

1. Extremely low residual moisture
2. Selective adsorption
3. Regenerability & long service life
4. Chemical stability & high adsorption capacity
5. Energy efficiency in automated systems

Anyone requiring consistently reliable, deeply dried air – especially in demanding industrial applications – benefits from molecular sieves as a high-performance, low-maintenance, and sustainable solution. The investment in molecular sieves pays off in the long term through process reliability, product quality, and energy savings.

No, molecular sieves generally do not place a strain on your system—in fact, they actively contribute to the protection and longevity of your system. When properly used and integrated into the existing system, molecular sieves act as an effective means of dehumidification and gas purification without causing mechanical or chemical stress.

Molecular sieves are purely physical adsorbents. They operate without mechanical stress or external energy input (except during regeneration) and therefore place no strain on pipes, equipment, or system components. When correctly designed and installed—e.g., in desiccant cartridges or adsorber vessels— the pressure drop is minimal. Flow occurs without a significant increase in energy consumption. Molecular sieves do not react with metals, plastics, or seals, thus eliminating corrosion or chemical decomposition in the system. Furthermore, they do not release any pollutants into the process media.

By removing moisture and contaminants, molecular sieves play a key role in preventing corrosion, icing, aging, or biofouling in pipes, valves, and sensors—particularly important in compressed air, gas, and hydraulic systems. Molecular sieves are safe, passive, and efficient components that actively protect your system rather than burdening it.

Yes, molecular sieves are extremely effective even at low humidity. Unlike many other desiccants, molecular sieves retain their high adsorption performance even when the moisture content in the ambient air or gas stream is already very low.

Thanks to their special crystal structure – especially in types such as 3A or 4A – they can selectively adsorb even the smallest amounts of water vapor. This makes them ideal for applications with extremely low dew point requirements down to -80°C, such as in semiconductor manufacturing, medical technology, or gas processing. Unlike conventional desiccants, molecular sieves retain their full adsorption capacity even at relative humidity below 10%. This reliably ensures dry processes, protects sensitive components, and increases operational reliability – even when only minimal amounts of moisture need to be removed.

Molecular sieves are therefore particularly suitable for demanding drying processes at low humidity. They offer stable adsorption performance where other desiccants are no longer sufficient – ideal for all applications where even the smallest amounts of moisture can cause problems.

The efficiency of molecular sieves decreases with increasing temperature because the adsorption of water molecules is an exothermic process—meaning: the higher the temperature, the lower the adsorption capacity. Nevertheless, molecular sieves retain their functionality even at higher temperatures and offer more stable performance over a wider temperature range compared to other desiccants such as silica gel or activated carbon.

Typically, the optimal operating temperature for adsorption is between 20°C and 40°C. At temperatures of approximately 80°C, water absorption is still possible, but reduced – efficiency decreases because the thermal movement of the molecules increases, thus weakening the binding forces in the sieve. They are particularly suitable for high-temperature applications when temperature peaks occur only briefly or when the cycle is specifically designed for adsorption at low temperatures and regeneration at high temperatures.

If the temperature is increased further (e.g., to 150–300°C), the opposite process begins: thermal regeneration. In this range, the previously absorbed moisture is released again—a desired effect in cyclically operated systems.

Molecular sieves are used across industries – wherever not only moisture but also unwanted gases and organic compounds need to be removed in a controlled manner. Their high adsorption performance, selectivity, and chemical stability make them an indispensable component in numerous industrial applications. They contribute significantly to product safety, process stability, and energy efficiency. Our products are primarily used in the following industries:

Oil and gas processing, water treatment, plastic granulate drying, natural gas and biogas industry, museums, laboratories and insulating glass.

Yes, molecular sieves are generally considered safe and non-toxic when handled properly. They are usually made of zeolites – natural or synthetically produced aluminosilicates – which are chemically inert, non-flammable, and environmentally safe. Molecular sieves do not release harmful substances and do not react with other materials under normal use conditions. However, as with any powdered industrial product, the use of gloves and respiratory protection is recommended when handling large quantities or loose fills.

Their chemical stability and environmental compatibility make molecular sieves a reliable and clean adsorbent in a wide variety of industries.

That depends entirely. Disposing of molecular sieves is generally straightforward, but depends on the specific application and the type of load. Fresh, unused, or solely steam-laden molecular sieves are generally considered non-hazardous waste and can – depending on local regulations – be disposed of with domestic or commercial waste or thermally recycled.

Spent molecular sieves containing foreign substances (e.g., oils, solvents, gases) may, however, be considered contaminated waste and must be disposed of in accordance with applicable waste regulations (e.g., AVV in the EU). In such cases, an analysis of the contaminants and, if necessary, classification as hazardous waste is required. Always refer to the Safety Data Sheet (SDS) provided with the product.

Alternatively, molecular sieves can be thermally regenerated, allowing reuse instead of disposal – often the better option both ecologically and economically.

Our molecular sieves are available in various packaging units. These are typically:

• 250g, 500g
• 1kg, 3,5kg, 25kg, 140kg

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