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A material with pores capable of separating molecules on the basis of size. There are many types of molecular sieves according their applications. Like 3A, 4A, Pentasils, Mordenite, Zeolite etc. The type 3 sieve is used for natural gas dehydration, cracked gas drying, olefins drying, ethanol drying, etc. It is usually made by ion exchanging potassium onto a Type 4A in place of sodium. The 4A type is in a sodium form and an inexpensive adsorbent usually used for drying. It can also be used for carbon dioxide removal. Type 5 of this kind is used for separating normal straight chain hydrocarbons from branched hydrocarbons. Type 13 is another molecular sieve of highest theoretical capacity adsorbent and very good mass transfer rates. It can remove impurities in large to fit into a Type A crystal and is commonly used to separate nitrogen from oxygen. Type Y can adsorb hydrophobic molecules in the presence of water and has mild acid resistance. Pentasils is a high silica/alumina ratio crystal that can remove organics from gas and liquid streams containing water. Mordenite is a highly acid resistance absorbent. A wide range of molecular sieves is manufactured by host of manufacturers.
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