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| | MOLECULAR SIEVES Basic information |
| Product Name: | MOLECULAR SIEVES | | Synonyms: | MOLECULAR SIEVE 13X 1/16;MOLECULAR SIEVE 3A 1/16;MOLECULAR SIEVE 4A 1/16;MOLECULAR SIEVE 5A 1/16;MOLECULAR SIEVES, 5A;MOLECULAR SIEVES 3A 1/16;MOLECULAR SIEVES 3A 1/8;MOLECULAR SIEVES 3D | | CAS: | 12173-28-3 | | MF: | AlCaH9KNaO6Si2(-2) | | MW: | 290.38 | | EINECS: | 215-283-8 | | Product Categories: | | | Mol File: | 12173-28-3.mol |  |
| | MOLECULAR SIEVES Chemical Properties |
| | MOLECULAR SIEVES Usage And Synthesis |
| Agricultural Uses | Molecular sieves are a group of adsorptive desiccants
which are crystalline aluminosilicates, chemically
similar to clays and feldspars, belonging to a class of
minerals known as zeolites. The most important
characteristic of these materials is their ability to undergo
dehydration with little or no change in crystal structure.
The dehydrated crystals are interlaced with regularly
spaced channels of molecular dimensions, comprising
almost 50% of the total volume of crystals.
The empty cavities in activated molecular sieve
crystals have a strong tendency to recapture the water
molecules that have been driven out. This tendency is so
strong that if no water is present, they will accept any
material that can enter or filter into them. However, only
those molecules that are small enough to pass through the
pores of the crystal can enter the cavities and be adsorbed
on the interior surface. This sieving or screening action,
which makes it possible to separate smaller molecules
from the larger ones, is the most unusual characteristic of
molecular sieves.
Molecular sieves are used in many fields of
technology to dry gases and liquids. They are also used for selective molecular separations based on such size
and polar properties as ion-exchangers, as catalysts and
in petroleum industry to remove normal paraffins from
distillates. | | Synthesis | 1. Hydrothermal Synthesis Method
It is used to produce products of higher purity and to synthesize molecular sieves that do not exist in nature. The silicon-containing compounds (water glass, silica sol, etc.), aluminum-containing compounds (hydrated alumina, aluminum salts, etc.), alkali (sodium hydroxide, potassium hydroxide, etc.) and water are mixed in appropriate proportions, and then heated for a certain period of time in a hot pressure kettle, that is, the molecular sieve crystals are precipitated.
2. Hydrothermal transformation method
In the presence of excess alkali, solid aluminum silicate hydrothermal transformation into molecular sieve. The raw materials used are kaolin, bentonite, diatomaceous earth, etc., can also be used to synthesize the silica-aluminum gel particles. This method is low cost, but the purity of the product is less than hydrothermal synthesis.
3. Ion exchange method
Usually in an aqueous solution Na-molecular sieves into molecular sieves containing the desired cations. |
| | MOLECULAR SIEVES Preparation Products And Raw materials |
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