Molecular sieves 3A are widely used in industrial and commercial applications for selective adsorption of water and small molecules. Their primary application is dehydration of gases and liquids, where they effectively remove moisture without adsorbing larger molecules. This makes them ideal for drying petroleum cracking gas, ethanol, and refrigerants.

In the petrochemical industry, 3A molecular sieves are used to dry unsaturated hydrocarbons such as ethylene, propylene, and butadiene, helping to prevent equipment corrosion and catalyst poisoning. They are also employed in the purification of natural gas and air drying systems.

Another key use is in the ethanol industry, where 3A sieves are critical in the dehydration of bioethanol to produce fuel-grade ethanol by removing water through pressure swing adsorption (PSA) processes.

Due to their potassium ion exchange that reduces the pore size, they selectively adsorb water while excluding larger molecules like alcohols and hydrocarbons, making them highly efficient in solvent drying and purification processes. They are also used in laboratory settings and in the packaging of sensitive materials to maintain low humidity environments.