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Mol sieve 4a made by 4A zeolite powder with attapulgite clay, it is sodium form of type A zeolite crystal structure with an effective pore opening of about 4 angstroms (0.4 nm).
Mol sieve 4a can 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 dioxide and straight chain hydrocarbons. Branched chain hydrocarbons and aromatics are excluded.
Mol sieve 4a is an alkali metal aluminosilicate with an effective pore opening of approximately 4 angstroms. The sodium form of type A is widely used as a general-purpose drying agent and has good physical and adsorption properties. Type 4A beads can be used to adsorb water, ammonia, methanol, ethanol and carbon dioxide. This type of molecular sieve is often used to remove moisture from gas and liquid streams, where co-adsorption of sulfur compounds and carbon dioxide is not a concern.
-Used for drying and removing of CO2 from natural gas, LPG, air, etc.
-Used for removal of hydrocarbons, ammonia and methanol from gas streams (ammonia syn gas treating).
-Used in dehydration of refrigerant and air in the air break units of buses, trucks and locomotives.
-Packed in small bags for packing desiccant for foods, electronics elements, drugs etc.
Regeneration Molecular Sieve should be in typical cyclic systems constitutes removal of the adsorbate from the molecular sieve bed by heating and purging with a carrier gas.
Sufficient heat must be applied to raise the temperature of the adsorbate, the adsorbent and the vessel to vaporize the liquid and offset the heat of wetting the molecular-sieve surface. The bed temperature is critical in regeneration. Bed temperatures in the 175-260鈩?range are usually employed for type 3A. This lower range minimizes polymerization of olefins on the molecular sieve surfaces when such materials are present in the gas. Slow heat up is recommended since most olefinic materials will be removed at minimum temperatures, 4A, 5A and 13X sieves require temperatures in the 200-315鈩?range.
After regeneration, a cooling period is necessary to reduce the molecular sieve temperature to within 15鈩?of the temperature of the stream to be processed.
For optimum regeneration, gas flow should be countercurrent to adsorption during the heat up cycle and concurrent (relative to the process stream) during cooling.
Alternatively, small quantities of molecular sieves may be dried in the absence of a purge gas by oven heating followed by slow cooling in a closed system, such as a desiccator.China Molecular Sieve