CAS number：12173-28-3
molecular formula：AlCaH9KNaO6Si2(-2)
molecular weight：290.38
EINECS number：215-283-8

English synonyms

MOLECULAR SIEVES;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

Related categories

Silane reagent; chemical raw material

Introduction

Molecular sieves are aluminosilicate crystals, which can be artificially synthesized by metal aluminum, water glass, alkali and other related raw materials at a certain temperature and pressure.
Molecular sieve usually contains a large amount of crystal water. If it is heated to a certain temperature, it will lose crystal water, leaving a large number of very regular and neat holes, each hole is only about 1/500,000 of the size of a hair. . Different varieties of molecular sieves have different crystal structures, pore shapes and sizes. This is determined by the chemical composition as well as the temperature and pressure when the crystals are formed. The most common molecular sieves are type A, type X, and type Y. A-type molecular sieves appear cubes under ordinary microscopes. The crystals of X-type and Y-type molecular sieves are spherical when observed under a general microscope. The silicon content of the Y type is higher than that of the X type, and the high temperature resistance is good. Molecular sieves have selective adsorption properties, which can sieve and separate gaseous and liquid molecules of different substances, and also have certain properties of catalysts and ion exchange properties. Therefore, it can be used for drying and purification of certain gases, as well as for dehydration, purification and concentration of certain liquid substances, and can also be used as catalysts and exchangers. At present, molecular sieves have been widely used in many aspects such as chemistry, chemical industry, oil refining, metallurgy, precision machinery, radio, atomic energy, environmental protection, biological experiments and comprehensive utilization of seawater.

Chemical properties

Form: white powder
parameter
Relative crystallinity: ≥88%
Cell constant: 2.456-2.472nm
Average particle size: less than 6μm
SiO2/Al2O3:≥5.3
SSA: ≥660m2/g
Na2O: ≤12.5%
LOI (loss on ignition): ≤15%
Static water absorption value: ≥32%

Use

●  Y-type molecular sieves have large specific surface area and high intragranular diffusion rate. Due to the characteristics of structure and performance, Y-type molecular sieves have been widely used in the fields of catalytic cracking, hydrocracking and isomerization of petroleum refining and other fields.

●  used as desiccant

Production method

●  1. Hydrothermal synthesis method
It is used to prepare products with higher purity and to synthesize molecular sieves that do not exist in nature. Mix silicon-containing compounds (water glass, silica sol, etc.), aluminum-containing compounds (hydrated alumina, aluminum salts, etc.), alkalis (sodium hydroxide, potassium hydroxide, etc.) and water in appropriate proportions and heat in an autoclave After a certain period of time, molecular sieve crystals are precipitated.
2. Hydrothermal conversion method
In the presence of excess base, the solid aluminosilicate is hydrothermally converted to molecular sieves. The raw materials used are kaolin, bentonite, diatomaceous earth, etc., and synthetic silica-alumina gel particles can also be used. The cost of this method is low, but the product purity is not as good as that of the hydrothermal synthesis method.
3. Ion exchange method
Na-molecular sieves are usually converted in aqueous solution to molecular sieves containing the desired cations.

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