Introduction 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. Regeneration Chemxin molecular sieve type 4a can be regenerated by either heating in the case of thermal swing processes; or by lowering the pressure in the case of pressure swing processes. To remove moisture from a 4a molecular sieve, a temperature of 250-280°c is required. A properly regenerated molecular sieve can give moisture dew points below -100°c. The outlet concentrations on a pressure swing process will depend on the gas present, and on the conditions of the process Size 4a - zeolites are available in beads of 1-2 mm(10x18 mesh), 2-3 mm(8x12 mesh), 2.5-5 mm(4x8 mesh) and as powder, and in pellet 1.6mm, 3.2mm. Attention To avoid damp and pre-adsorption of organic before running, or must to be reactivated.
