3A Molecular Sieve for Cracked Gas Dehydration

3A molecular sieve is a potassium-type A-type silicoaluminosilicate crystal, with its core characteristic being an exact pore diameter of 3 angstroms (0.3 nm). The dynamic diameter of water molecules is approximately 2.65 Å, allowing them to freely enter the pore channels; hydrocarbons such as ethylene (~4.2 Å) and propylene (~4.5 Å) have diameters greater than 3 angstroms and are blocked outside. This is the most crucial advantage of 3A molecular sieve in the drying of cracked gas.

The key role in cracking gas drying：

Deep dehydration: Reduce the water content of cracking gas from hundreds of ppm to below 1 ppm, with the dew point reaching -70℃ or even lower, ensuring that the deep cooling separation unit does not experience ice blockage

Protect olefin products: Precise control of pore size, unsaturated hydrocarbons such as ethylene, propylene, and butadiene cannot enter the pores, avoiding product loss

Prevent coking and deactivation: Since the olefins are not adsorbed into the pores, they will not undergo polymerization and coking on the surface of the molecular sieve, significantly extending the service life of the adsorbent (up to 2-3 years in normal operation)

Protect downstream catalysts: Avoid catalyst poisoning caused by moisture

Apart from drying cracked gas, 3A molecular sieves are also widely used in the petrochemical industry for:

Deep drying of ethylene and propylene products (for polymer-grade raw materials)

Drying of unsaturated hydrocarbons such as butadiene and acetylene

Dehydration of natural gas (when low co-adsorption is required)

Drying of refrigerants and insulating gases

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