Performance and structure of molecular sieve

Performance: zeolite powdery crystals with metallic luster, hardness of 3 to 5, the relative density of 2 to 2.8, color natural zeolite, synthetic zeolite powder obtained as a white, water-insoluble, heat stability and acid resistance as SiO2 / Al2O3 composition ratio increases and improved. Molecular sieves have a great specific surface area, up to 300 ~ 1000m2 / g, the inner surface of the crystal highly polarized, as a class of highly efficient adsorbents, also a type of solid acid, the surface has a high acid concentration and acid strength, can cause carbonium catalytic ionic reactions. When the composition of the metal ions and other ions in solution were exchanged, adjustable aperture, changes its absorption properties and catalytic properties, which molecular sieve catalyst prepared with different properties.

Structure: proteoglycan thus formed polymer tortuous coiled, forming a sieve-like microporous structure, known as molecular sieves. Microporous molecular sieve which only allows material through is less than, greater than the pores of macromolecular substances, bacteria and the like having a barrier function is. The matrix becomes the limiting diffusion of harmful substances such as bacteria defensive barrier. Hemolytic streptococcus and cancer cells can produce hyaluronidase, the decomposition of proteoglycan, destruction of the matrix structure, to be spread. On binding proteoglycan aggregate also many hydrophilic groups, capable of binding water molecules, forming extracellular "reservoirs"

functions and features of Molecular sieve

The porous material has been widely used in many fields, such as the main catalytic microporous molecular sieve material, adsorption and ion exchange material separation materials plays an increasingly important role in oil processing, petrochemicals, fine chemicals, and household chemicals .
molecular sieves(also known as a synthetic zeolite) is a microporous aluminosilicate crystalline silicon. It is made of silicon oxide, aluminum oxide tetrahedra basic skeleton structure, there is a metal cation in the crystal lattice (such as Na +, K +, Ca2 +, Li +, etc.), in order to balance the negative charge excess crystals. According to their type of zeolite crystal structure is divided into: A type, X-type, Y type.
Zeolite relevant standards:
"3a molecular sieve" "4A molecular sieve" "5a molecular sieve and test methods" "13X molecular sieve"
"Water assay method static sieve" "sieve dynamic water assay method"
"Granular sieve size determination," "Determination of bulk density of molecular sieve" "sieve crush strength test method", "Standard Test Method for molecular sieve desiccant cooling systems with anti-wear performance," "Determination of dynamic zeolite adsorption of carbon dioxide."
"Industrial activated alumina," "air separation plant with activated alumina acceptance technical conditions"

The role of zeolite molecular sieves

The zeolite molecular sieves is heated to about 200 ℃ water to evaporated, to obtain activated zeolite, porous sponge is formed, so that the cation exchange properties of adsorption and to play. And when the water is heated to escape, more open channels and cavities, corresponding to greater internal surface area, and inside the zeolite crystal cave after dehydration with strong Coulomb field and polarity, plus dispersion forces and static electricity and makes zeolite showed a strong adsorption.
3a zeolite molecular sieves has a high temperature properties, but the temperature is too high will destroy its structure so that it loses ion exchange. Under normal circumstances, the ignition 500 ℃ ~ 550 ℃ can improve the mechanical strength of the pore volume can be increased to increase the specific surface area, but also increase locomotor activity cation ion exchange is more fully.
Depends on the thermal stability of the natural zeolite of silicon, aluminum, and the balance 13x zeolite molecular sieves cation ratio, generally within the range of variation in the composition, the high silicon content, the better the stability. Some changes in the balance of cationic nature, for the stability of the crystals have a significant impact, such as calcium-based natural clinoptilolite can decompose below 500 ℃, if the same sample with potassium ion exchange, it is still crystal temperature of 800 ℃ destruction.