Zeolites groups

To reduce pollution, Dow developed a new catalyst system from the mor-denite-zeolite group to replace phosophoric acid or aluminum chloride catalysts. The new catalysts eliminates the disposal of acid wastes and handling corrosive materials. 

The Zeolite Group. Amethyst Galleries, Inc., http //galleries.com/minerals/silicate/zeolites.htm... 

Pectolite [NaCa2Si30g(0H)] is found as white to translucent acicular radiating crystalline aggregates, often in association with the zeolite group of minerals, which are discussed later. In the crystal strucmre of pectolite, Csl and Na" occupy the sites between the single chains as described for pyroxenes. Chemical substitutions of Mn , Mg and Fe, for Na and Ca are common. The substitutions may be detected optically because they pro-... 

Humpton and Ormsby (1976) presented scanning electron microscope photographs that show the range of morphologies adopted by the many members of the zeolite group of minerals. For more detail on the many intricate structures of natural and synthetic zeolites, see Breck (1974), Sand and Mumpton (1977), Flanigen (1977), or Barrer (1978). 

Zeolite, zeolite group A collective term for a family of aluminosilicate minerals characterized by framework structures that allow easy access and exchange of cations and small molecules (see chapter 2), The name derives from the Greek terms zein, meaning to boil, and lithos, meaning stone. The term is also applied to synthetic materials of comparable composition, crystal structure, and physical properties (see chapter 2). 

The zeolite group of minerals provides further examples of defect structures. These are complex aluminosilicates, the crystals of which have a rigid framework of Al, Si, and O atoms in which there are continuous channels water molecules may enter or leave the crystals by way of these channels, the amount of water in the crystals being variable (W. K. Taylor, 1930, 1934). (In normal hydrates the structure collapses when water is removed, a new structure being formed.) A simple substance in which the same thing occurs is calcium sulphate subhydrate CaS04.0-fH20 (Bunn, 1941). 

Research has continued apace over the years to develop new organic ion-cxchangc organic polymers—the details of most are proprietary. Both natural and synthetic zeolites also are used in ion-exchange processes, but their extreme importance as catalysts has tended to overshadow their applications for deionizing purposes. See also Adsorption and Zeolite Group. 

See also Water Treatment (Bailer) and Zeolite Group. 

ZEOLITE GROUP. To the zeolite group of minerals belong a number of hydrous silicates of aluminum which also ordinarily contain sodium or calcium, but rarely they may carry barium, strontium, magnesium, and... 

The Zeolite Group. Mineral Gallery. Available from minerals/silicate/zeolites.htm>. 

The differentiation of individual mineral species and mineral nomenclature is a continuing problem. In the zeolite group of minerals, the situation has been improved greatly as the result of recent structural analyses. At present, I believe the zeolite mineral group includes 34 different species. Five of these minerals have been discovered since 1950 garronite was reported in 1962 (79) (Table I). 

Zeolite Any of the minerals of the zeolite group. Aluminosilicate minerals with an open framework structure that allows for easily reversible hydration, gas adsorption, and either cation or anion exchange. 

The 13 International Zeolite Conference has been held in Montpellier, France, from July 8 to 13,2001, organized by the French Zeolite Group on behalf of the IZA. It has been preceded by a School on the Industrial Applications of Zeolites, held in Poitiers, and followed by a Field Trip in the natural zeolite localities of Massif Central. 

Capturing of the Fe + ions in the zeolite a-cation-exchange positions was first considered theoretically in [81], The Fe + ion grafted to the zeolite framework, or captured by a zeolite lattice defect =Si-0-Fe-0-Si= was proposed in [82] as an active center with low coordination of Fe +. Such structure could be emerged as the result of iron immobilization on vicinal hydroxyl zeolite groups. Also, it was found that addition of trimethylaluminum to Fe-silicalite drastically improves the catalyst activity in the process (20.10). Based on these data a conclusion about the formation of FeAlO active species was made [83],... 

Solid acids, zeolites Group Vin metals ZSM-5-zeolites... 

Gottardi proposed a classification scheme that is similar to the SBU classification of Breck et al. (1974) (Table 6.2), except that it includes some historical context of how zeolites were discovered and named. This scheme uses a combination of zeolite group names that have specific SBUs and is widely used by geologists and consists of some complex structural units of tetrahedron, whether finite or infinite, which are (a) the chain of fibrous zeolites (b) the single-connected 4-ring chain (c) the double-connected 4-ring chain ... 

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