5A molecular sieve is an alkali metal aluminosilicate with a pore size of 5 angstroms (0.5 nanometers), made from calcium ion exchange in an A-type molecular sieve. Due to its internal structure containing numerous 5-angstrom crystal adsorption cavities, it can adsorb molecules with a diameter smaller than 5 angstroms while not adsorbing any molecules with a diameter greater than 5 angstroms. It is primarily used for the separation of normal paraffins, pressure swing adsorption separation, and the co-adsorption of water and carbon dioxide.