Zeolites chemical formulae

In this chapter, we describe the design and important properties of supra-molecularly organized dye molecules in the channels of hexagonal nanocrystals. We focus on zeolite L as a host. The principles, however, hold for other materials as well. As an example, we mention ZSM-12 for which some preliminary results have been reported [55], We have developed different methods for preparing well-defined dye-zeolite materials, working for cationic dyes, neutral dyes, and combinations of them [3, 22, 25, 52], The formula and trivial names of some dyes that so far have been inserted in zeolite L are reported in Section II.C. The properties of natural and commercially available zeolites can be influenced dramatically by impurities formed by transition metals, chloride, aluminiumoxide, and others. This fact is not always sufficiently taken care of. In this chapter, we only report results on chemically pure zeolites, the synthesis of which is described in [53]. 

Commercially significant zeolites include the synthetic zeolites type A (LTA), X (FAU), Y (FAU), L (LTL), mordenite (MOR), ZSM-5 (MFI), beta ( BEA/BEC), MCM-22 (MTW), zeolites E (EDI) andW (MER) and the natural zeolites mordenite (MOR), chabazite (CHA), erionite (ERl) and clinoptiloUte (HEU). Details of the structures of some of these are given in this section. Tables in each section lists the type material (the common name for the material for which the three letter code was established), the chemical formula representative of the unit cell contents for the type material, the space group and lattice parameters, the pore structure and known mineral and synthetic forms. 

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

Using the most simple expression of the chemical formulae for the minerals cited above, a chemical system can be constructed using the components Na-K-Al-Si-l O. Initially we will assume that hydrogen and oxygen are always combined in a 2 1 ratio. This is a valid approximation for zeolite structures but not for phyllosilicates, a point to be discussed later. 

Zeolites are porous crystalline aluminosilicates that are made of assemblies of Si04 and AIO4 tetrahedra joined together through shared oxygen atoms. The general chemical formula for zeolites is ... 

The blossoming of new materials has been so rapid that the nomenclature of ordered mesoporous materials is in the wild state in which zeolite nomenclature was thirty years ago. A set of rules for writing a standardized crystal chemical formula for both microporous and mesoporous materials has been established by the Physical Chemistry Division of the International Union for Pure and Applied Chemistry, through its Commission on Colloid and Surface Chemistry including Catalysis [65]. The impact of this nomenclature on the activity of the scientists dealing with mesoporous materials has still to be verified. 

The lUPAC recommendations on the nomenclature of microporous and mesoporous inorganic solids define a rather complex naming for porous materials based on its crystal chemical formula, which for zeolites with a confirmed FTC can be safely reduced to... 

It is worth mentioning the recent and interesting discovery of the aluminosilicate AS-1 of topology DFT [37]. This aluminosilicate of chemical formula l(C2Hi(>N2)o.5l[AlSi02] can be synthesized with ethylenediamine as the OSDA only in fluoride media. The role of the fluoride ions is here rather tricky but in this case the addition of HF favours the diprotonation of the ethylenediamine molecules. AS-1 opens new prospects about the use of amines in fluoride media for the preparation of novel low-silica zeolites. 

Zeolite CEC (meq./g) Channel/pore diameter (A) Pore volume (%) Specific gravity Chemical formula... 

Zeolite structures have the general chemical formula ... 

Chemical structure of the Silicalite-1 zeolite (a), schematic representation of a functionalized silica nanotube (b), chemical formula of silane functional group used in the silica nanotube (c). 

Synthetic Zeolites. Many new crystalline 2eohtes have been synthesi2ed and several fulfill important functions in the chemical and petroleum industries and in consumer products such as detergents. The stmctural formula of a 2eohte is based on the crystal unit cell, the smallest unit of stmcture,... 

Zeolites are crystalline aluminosilicates of group lA and group llA elements, such as sodium, potassium, magnesium and calcium [2]. Chemically, they are represented by the empirical formula ... 

Synthetic Zeolites. Many new cry stalliue zeolites have been. synthesized and several fulfill important functions in the chemical and petroleum industries and in consumer products such as detergents. The structural formula of a zeolite is based on the crystal unit cell, the smallest unit of structure, represented by At, ((Alt), >, (SiO i t/ H 0. where n is the valence of cation M. ir is the number of water molecules per unit cell, v and r are. respectively, the number of AlOa and SiOj tetrahedra per unit cell, and y/v usually has values of 1-5. Examples of important synthetic zeolites are shown in Table I. 

An alternative method of describing the products of the metal ammonium fluoride process utilizes the calculated "z" values which were described above, together with the chemical analyses to express the products in terms of mole fractions of framework tetrahedra, i.e., the "T02" formula. The starting zeolite may be expressed as ... 

Zeolites are crystalline aluminosilicates (synthetic and natural), with a chemical composition which corresponds to the general formula... 

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