Zeolite aluminum silicate

Zeolite Pellets or granules of aluminum silicate, used in water treatment or aircleaning applications. 

To improve the yield of mono- and dimethylamines, a shape selective catalyst has been tried. Carhogenic sieves are microporous materials (similar to zeolites), which have catalytic as well as shape selective properties. Comhining the amorphous aluminum silicate catalyst (used for producing the amines) with carhogenic sieves gave higher yeilds of the more valuable MMA and DMA. ... 

Several different possible zeolite structures may result, and if the sodium content is too high, calcium and magnesium are excluded and a hard zeolite scale of sodium-aluminum silicate preferentially forms. If only calcium is present, calcium-aluminum silicate zeolite forms, also as a hard scale. If only magnesium is present in solution, it forms the flocculant magnesium aluminate, MgAl204. 

Today n-paraffms are exclusively produced from the corresponding distillation cuts of paraffin-rich oils with the use of molecular sieves. Molecular sieves are synthetically manufactured aluminum silicates of the zeolite type, which after dehydration have hollow spaces of specific diameters with openings of specific diameters. The molecules are then able to penetrate the openings in the correct size and form and are held in the hollow spaces by electrostatic or van der Waals forces. The diameter of the zeolite type used for the production of paraffins is 5 A and is refined so that the n-paraffins (C5-C24) can penetrate the hollow spaces while the iso- and cyclic paraffins are unable to pass through [15]. 

Octafining A process for isomerizing m-xylene to o- and p-xylene, developed by the Atlantic Richfield Company in 1960. The catalyst was originally platinum on an aluminum silicate base now a zeolite base is used. The reaction takes place in a hydrogen atmosphere. Hydrocarbon Research installed units in Argentina and the USSR. 

Zeolite minerals are hydrous-aluminum-silicates whose general chemical formula can be expressed as... 

Most home water softeners are based on ion-exchange resins. The first ion-exchange materials used in softening water were naturally occurring polymeric aluminum silicates called zeolites. At present, synthetic zeolites are also used for this purpose. Today, most... 

After soil and clays, natural and synthetic aluminum silicates and synthetic zeolites were tested as ion-exchange materials by other scientists. However, the first practical applications of ion exchange took place hi the early 20th century. 

ANALCIME. A common zeolite mineral, NaAlSi2C>6 H20, a hydrous soda-aluminum silicate. It crystallizes in the isometric system, hairiness, 5-5.5 specific gravity, 2.2. vitreous luster colorless to white but may be grayish, greenish, yellowish, or reddish. Its trapezohedral crystal resembles garnet but is softer it is distinguished from lcucitc only by chemical tests. 

These heterogeneous catalysis contain nickel, cobalt, molybdenum, tungsten, platinum, or palladium on acidic aluminum silicate or zeolite supports. As with reforming catalysts, the catalysts here are also believed to be... 

The natural clay minerals are hydrous aluminum silicates with iron or magnesium replacing aluminum wholly or in part, and with alkali or alkaline earth metals present as essential constituents in some others. Their acidic properties and natural abundance have favored their use as catalysts for cracking of heavy petroleum fractions. With the exception of zeolites and some specially treated mixed oxides for which superacid properties have been claimed, the acidity as measured by the color changes of absorbed Hammett bases is generally far below the superacidity range. They are inactive for alkane isomerization and cracking below 100 °C and need co-acids to reach superacidity. 

Zeolite A group of aluminum silicate minerals that may form under low metamorphic temperatures and pressures. 

The main types of inorganic sorbents are silica gels, molecular sieves/zeolites, aluminum oxides and magnesium silicates. Carbon-based sorbents include activated charcoals, carbon blacks, graphihzed carbon blacks and graphitized molecular sieves. Styrene-divinylbenzene copolymers, ethylvinylbenzene/divinylbenzene... 

These materials are natural or artificial sodium aluminum silicates (e.g., Na2Al2Si08), which may be considered as complex salts of orthosilicic acid (H4Si04). When hard water is allowed to flow upward through a bed of granular zeolite in a vertical vessel, reactions of the type illustrated by the following equations result ... 

These natural minerals are alkali aluminum silicates and have been used as molecular sieves and cation exchangers. Recently they have been used to control some organic photochemical reactions, du Pont chemists1 have prepared lithiated zeolites by treatment of sodium aluminum silicates such as zeolite 13X with LiNO,. These silicates, designated Li-X and Li-Y, can effect rearrangement of a-alkyl-deoxybenzoins top-alkylbenzophenones in nearly quantitative yield. Thus photolysis... 

In 1977, the German firm Hankel patented the use of synthetic zeolites as a partial replacement for phosphates. The sodium aluminum silicates as zeolites have a particular lattice structure capable of absorbing heavy metal cations through ion exchange process. The role of zeolites that were added to TPS was to soften water by rapid reaction with calcium at normal temperature [4]. 

The most widely used form of zeolites is t5 e A—which are hydrated sodium aluminum silicates of empirical formula Na20 Al203 X Si02-yH20. 

Zeolite Zeolite on aluminum silicate Catalytic cracking... 

Molecular sieve zeolites constitute a class of stationary phase that combines exclusion with specific adsorption properties. These materials, which are crystalline aluminum silicates (commonly sodium or calcium aluminum silicates), have rigid, highly uniform three-dimensional porous structures containing up to 0.5ml/g of free pore volume, resulting when water of crystallization is removed by heating. Although munerous natural zeolites are known, most practical work is done with... 

Many other materials, including synthetic aluminas, aluminum carbonates, aluminum silicates, magnesium silicates, various forms of attapulgite and sepiolite (81-83), alumina-pillared acid-activated montmorillonite (84), synthetic mica mont-morillonite, HY-zeolite, zirconium phosphate (85), mica, kaolin, and synthetic hectorite (86), have been evaluated for their ability to purify virgin fats and oils, but none were as good as acid-activated bentonite. 

The information about synthetic mordenite properties was obtained in 1961 when Keough and Sand (7) found that H- and other forms of this crystalline aluminum silicate display high activity and selectivity in the reactions of hydrocarbon cracking and ethanol dehydration. Later this zeolite was shown (J, 2, 5, 7, 8, 10-13, 15, 16) an active catalyst in the reactions of isomerization, cracking, and alkylation of hydrocarbons and alcohol dehydration. However, the catalytic properties of mordenite have been studied insufEciently, compared with those of other zeolites. 

The high catalytic activity of H-mordenite seems to be uncommon, since (6, 9) amorphous aluminum silicates and zeolites which do not involve the metals of column VIII are not active in isomerization of saturated hydrocarbons under similar conditions. In addition, as has been shown by this research, the introduction of metal into H-mordenite does not increase the catalyst activity in n-pentane isomerization. For example, the yield of isopentane on H-mordenite and 0.5% Pd/HM at p = 30 atm and V = 1 hour" is about 50 wt % (12). 

AISi3C,2H33, Aluminum, tris[(tri-methylsilyl)methyl]-, 24 92 Al2Na20i4Si XH2O, Sodium aluminum silicate hydrate, 22 64, Zeolite Y, 22 64... 

Not only do these acids present an economic advantage over conventional acid technology, but there are also frequent selectivity eidiancements and changes in reactivity associated with the use of these heterogeneous catalysts. A number of different types of solid acids have been involved in synthetically useful reactions. They range from the hydrogen forms of various ion exchange resins and the perflourinated resin sulfonic acid, Nafion-H, to the amorphous acidic oxides, silica and aluminum silicate,the crystalline zeolites > and the natural clays. -9... 

Reaction of biphenyl with propylene over H-Y gave a 41% selectivity to 4-isopropyl biphenyl (8) at 76% conversion (Eqn. 22.4). The use of H-L zeolite gave comparable results but with H-M and H-ZSM-5 considerably lower conversions were obtained. When amorphous aluminum silicate was used as the catalyst a product mixture similar to those obtained with the crystalline zeolites was also obtained, suggesting that these reactions may be taking place on the exterior surface of the zeolites and not in the pores or cages. ... 

Indeed, the H2(ext/obs) ratio which is a measure of the reduction degree and therefore indicates if there is an interaction with the zeolite or between cerium and vanadium, exhibited different values, depending on the way of introduction and species formation. The catalyst treated with steam, EXV, presented a low H2 (ext/obs) ratio, which indicates a better reduction. On the other hand, the impregnated catalyst (IMPV) presented a high H2 (ext/obs) ratio, and thus low reduction. This could explain the indication that an interaction occurred during the treatment, with the formation of bimetallic or alloys or even the formation of aluminum silicate-metal interaction. 

The first attempt to employ ion exchange for commercial purposes was in 1896 by F. Harm, a German agricultural chemist, to remove Na and from sugar beet juice. The first synthetic ion exchange compounds were aluminum silicates called zeolites and were available commercially about 1903. 

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