MOLECULAR SIEVES (PREPARATION, PROPERTIES, APPLICATION)
Natural or synthetic zeolites consist of a hydrated aluminosilicate skeleton containing either a monovalent ion such as Na, K, or Li, or a divalent ion such as Ca, Sr, or Qa. Zeolites contain a rigid structure, a layered structure, or a semirigid structure. Synthetic zeolites are produced most frequentiy by autoclaving a sodium aluminate solution with a suspension of silicic acid at a pH of 8 to 10.5 with a temperature of 85 to 1l0 deg C, and then dehydrating the product, Since these artificial zeolites have a controlled diameter of 4A, 5A, or higher (Linde 13X), they are characterized by selectivity in absorbing only smaller molecules and by high adsorptive capacity at higher temperatures. Since they are polar adsorbents, they have a great affinity for polar substances such as water. At low concentrations of water vapor, molecular sieves have 6 to 10 times more adsorptive capacity than silica gel or activated aluminum oxide, Molecular sieves have found numerous applications in separating various impurities from the noble gases and from various organic compounds. Treatment of zeolites with potassium solutions leads to a decrease in the absorption of gases, whereas treatment with calcium solutions leads to absorption of even the larger gas molecules. The greater the amount of water in the silicate lattice, the greater is the absorptive capacity of the zeolite. Numerous applications of molecular sieves in removing H/sub 2/O, CO/sub 2/, CO, and H/sub 2/S from various gas streams are cited, At a pH of 5 to 11, ions such as Ag, Cu, Al, Zn, Sr, Ba, Ca, Co, Au, and K can be removed from solution, 117 references. (TTT)
- Research Organization:
- Inst. of Physical Chemistry, Academy of Sciences, Ukrainian SSR; Scientific Research Inst. of Basic Chemistry
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-15-002714
- OSTI ID:
- 4122186
- Journal Information:
- Uspekhi Khim., Vol. Vol: 29; Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ABSORPTION
ACIDS
ADSORPTION
AFFINITY
ALUMINATES
ALUMINUM
ALUMINUM OXIDES
ALUMINUM SILICATES
BARIUM
CALCIUM
CARBON DIOXIDE
CARBON MONOXIDE
CHEMICAL REACTIONS
COBALT
COLLOIDS
CONFIGURATION
COPPER
GASES
GELS
GOLD
HIGH TEMPERATURE
HYDROGEN SULFIDES
IMPURITIES
ION EXCHANGE MATERIALS
IONS
LITHIUM
MOLECULAR SIEVES
MOLECULES
NOBLE GASES
ORGANIC COMPOUNDS
POTASSIUM
PREPARATION
PRODUCTION
RARE GASES
SEPARATION PROCESSES
SILICON
SILVER
SODIUM
SOLUTIONS
STRONTIUM
SUSPENSIONS
VAPORS
WATER
ZEOLITES
ZINC