Chemxin Molecular Sieve type 4A is an alkali alumino silicate; it is the sodium form of the Type A crystal structure. 4A molecular sieve has an effective pore opening of about 4 angstroms (0.4nm). Chemxin type 4A molecular sieve will adsorb most molecules with a kinetic diameter of less than 4 angstroms and exclude those larger. Such adsorbable molecules include simple gas molecules such as oxygen, nitrogen, carbon dioxyde and straight chain hydrocarbons. Branched chain hydrocarbons and aromatics are excluded.