The pore size for molecular sieve is . It is mainly used to adsorb water, methanol, ethanol, sulfureted hydrogen, carbon dioxide, ethylene, propylene, does not adsorb any larger molecular than , and often used as desiccant in industrials.

Applications :
# Deep drying of air, Natural gas, alkane and refrigerant.
# Generation and purification of argon.
# Static dehydration of electronic element, pharmaceutical and unstable materials.
# Desiccant for paint, dope and foul etc.
# Type 4A molecular sieve is typically used in regenerable drying systems to remove water vapor or contaminants which have a smaller critical diameter than four angstroms.