Zeolites uses for

Molecular sieve Zeolites used for ion exchange in water treatment. 

Regeneration of high silica zeolite used for Beckmann rearrangement... 

OXYWELL A process for separating oxygen from air by PSA, using vacuum desorption from a zeolite. Used for medical oxygen generators, hence the name. Developed by Nippon Sanso. 

One of the important properties that make zeolites useful for catalysis is their acidity-particularly, their Bronsted acidity. The strength, location and accessibility of these sites will change depending on the structure of the zeoHte and its com-posihon (Si/Al). Therefore, it is important to be able to measure these differences... 

Zeolites used for the preparation of mixed-matrix membranes not only should have suitable pore size to allow selective permeation of a particular molecular component, but also should have appropriate particle size in the nanometer range... 

In addition to the epoxidation of olefins, zeolitic materials have been studied for other fine chemical transformations. Table 12.21 indexes the zeolites used for oxidative dehydrogenation of propane, direct hydroxylation of benzene to phenol and e-caprolactam synthesis. A recent review summarizes other reactions for which there is not enough space in the table [138, 139]. 

F. Harm A. Rumpler S. Mayert K. Halse Artificial zeolites used for removal of potassium from sugar juices. First synthetic industrial ion exchanger. Manufacture of sulfonated coals and suggestion for the removal of potassium from sugar juices. 1901-1902... 

Synthetic zeolites used for hydrocarbon cracking or isomerization reactions often have crystalline and amorphous components. This can be intentional, caused by the use of a binder, or could result from incomplete reaction during the production of the zeolite. Therefore, the percentage of... 

Table 8.2 Typical structure of medium pore zeolites useful for dewaxing...

The ratio between the two main products 24 and 25 depends on the type and acidity of zeolite used. For example, H-BEA with a higher acid outer surface demonstrated a high activity but a low selectivity of 24 in comparison to H-FER or H-US-Y catalysts. 

For many catalysts, the major component is the active material. Examples of such unsupported catalysts are the aluminosilicates and zeolites used for cracking petroleum fractions. One of the most widely used unsupported metal catalysts is the precious metal gauze as used, for example, in the oxidation of ammonia to nitric oxide in nitric acid plants. A very fast rate is needed to obtain the necessary selectivity to nitric oxide, so a low metal surface area and a short contact time are used. These gauze s are woven from fine wires (0.075 mm in diameter) of platinum alloy, usually platinum-rhodium. Several layers of these gauze s, which may be up to 3 m in diameter, are used. The methanol oxidation to formaldehyde is another process in which an unsupported metal catalyst is used, but here metallic silver is used in the form of a bed of granules. 

Holderich et al. obtained high yields (up to 81 %) of keto aldehyde (13) over H-FER after 6 h in the liquid phase at 110 °C with toluene as solvent [37]. H-US-Y catalysts perform well in the formation of (13). The H-US-Y (Si/Al = 48)-HCl catalyst, modified by treatment with dilute HCl (pH 2) according to the method described in the preceding section [35,38] is particularly active, even at high weight hourly space velocities. The performance of this catalytic system is comparable with that of the system described by Sheldon et al. [36]. Reaction in benzene at 80 °C for 2 h over dealuminated H-mordenite gave 100% conversion and 85 % selectivity for (13). The ratio of the two main products (13) and (14) depends on the type and acidity of the zeolite used. For example, H-BEA with a more acidic outer surface was highly active but the selectivity for (13) was lower than for H-FER or H-US-Y catalysts [37]. 

Table 5.2. Characteristics of zeolites used for the preparation of 5% Pt-zeolite catalysts.

At that time there were synthetic zeolites used for softening water by base exchange. These were amorphous sodium aluminosilicates. Active cracking catalysts were made from them by exchanging the sodium ions with other ions. 

Alkaline earth and rare earth metal cocation effects are reported in this paper for copper ion-exchanged ZSM-5 zeolites used for the catalytic decomposition of nitric oxide in 02- free, 02- rich, and wet streams. Severe steaming (20% H2O) of Na-ZSM-5 at temperatures above 6(X)°C leads to partial vitreous glass formation and dealumination. Unpromoted Cu-ZSM-5 catalysts suffer drastic loss of NO decomposition activity in wet gas streams at 500°C. Activity is partially recovered in dry gas. Copper migration out of the zeolite channels leading to CuO formation has been identified by STEM DX. In Ce/Cu-ZSM-5 catalysts the wet gas activity is greatly improved. CuO particle formation is less extensive and the dry gas activity is largely recovered upon removal of the water vapor. 

Permutit Trade name for a zeolite used for water softening. 

EPR metal carbonyl clusters ionic clusters structure and environment of duster in zeolite Useful for diaraderization of spe-des having unpaired electrons due to its high sensitivity, very small percentages of total metal loading are measurable. 

The zeolite used for the solid-state ion-exchange experiments with FeC -4H20 and Fe(COO)2 2H20 was prepared from a parent Na-Y zeolite (provided by Union Carbide) by 15-times repeated ion exchange with IN ammonium chloride solution, its idealized unit cell composition is H o.3(NH4)54 Nao.5[Ale4 gSi- 27.i0 84] ... 

Rare earth compounds are also used in numerous catalytic reactions in petrochemical industry. One example is the use of rare earth salts to stabilize zeolites used for the catalytic cracking of crude oils to gasoline. Rare earth doping increases the activity of these zeolites with the consequence of higher gasoline yields. In addition, these rare earth-modified catalysts have found expanded application as a consequence of the refineries use of residual or heavy crude oils which contain high levels of nickel, vanadium, and sulfur which attack zeolites and reduce their activity rare earths are more resistant to these catalytic poisons. ... 

For the exhausted adsorbents from gas phase adsorption, regeneration by thermal desorption is most commonly used. For example, activated carbon used to prevent contamination of air by organic solvents of low concentrations, and silica gel, activated alumina or zeolite used for dehumidification of gases are regenerated by high temperature steam, air or inert gases. In the case of organic adsorbates... 

The adsorbent normally used in both the vapour and the liquid processes is a zeolite molecular sieve. The particular zeolite used for extracting water from an ethanol-water liquid or vapour stream is the 3A variety in which sodium has been replaced by potassium by ion exchange. As the molecular... 

Guzman, A. Zuazo, I. Feller, A. et al. On the formation of the acid sites in lanthanum exchanged X zeolites used for isobutane/cis-2-butene alkylation. Micropor. Mesopor. Mater. 2005, 83, 309-318. 

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