International Zeolite Association three-letter coding

Zeolites are aluminosilicates characterized by a network of silicon and aluminum tetrahedra with the general formula Mx(A102)x(Si02)Y. The M are cations that are necessary to balance the formal negative charge on the aluminum atoms. The tetrahedra are linked to form repeating cavities or channels of well-defined size and shape. Materials with porous structures similar to zeolites but with other atoms in the framework (P, V, Ti, etc.), as a class are referred to as zeotypes. The structure committee of the International Zeolite Association (IZA http //www.iza-online.org/) has assigned, as of July 1st 2007, 176 framework codes (three capital letters) to these materials. These mnemonic codes do not depend on the composition (i.e. the distribution of different atom types) but only describe the three-dimensional labyrinth of framework atoms. 

The nomenclature of zeolites is rather arbitrary and follows no obvious rules because every producer of synthetic zeolites uses his/her own acronyms for the materials. However, as mentioned before, at least the structure types of the different zeolites have a unique code. For example, FAU represents Faujasite-type zeolites, LTA Linde Type A zeolites, MFI Mobile Five, and BEA Zeolite Beta. The structure commission of the International Zeolite Association (IZA) is the committee granting the respective three-letter codes [4], Some typical zeolites, which are of importance as catalysts in petrochemistry, will be described in the following sections. 

Zeolites are now defined as solids that possess a framework of tetrahedra which are all corner-sharing and include a degree of opermess such as channels or cavities. Each framework type is issued a unique three letter code by the Structure Commission of the International Zeolite Association. " At the end of February 2007, there were 176 framework types. This definition does not specify atom types. 

GIS). A three letter code (e.g. GIS) is assigned to confirmed framework types by the Structure Commission of the International Zeolite Association according to rules set up by an 1UPAC Commission on Zeolite Nomenclature [3,4]. The codes are normally derived from the name of the zeolite or type material , e.g. FAU from the mineral faujasite, LTA from Linde Type A, and MFI from ZSM-5 (Zeolite Socony Mobil - five). Information pertinent to these framework types is published in the Atlas of Zeolite Framework Types [5] and on the internet at http //www.iza-strncture.org/databases/. As new codes are approved, they arc announced on the IZA Structure Commission s WWW pages (http //www.iza-structure.org/) and included in the internet version of the Atlas. As of January 2005, 161 zeolite framework types had been confirmed by the Structure Commission. In this chapter, all references to materials whose framework types are known will be accompanied by the appropriate three letter code in boldface type. 

Three-letter code of the International Zeolite Association for zeolite A Lanthanum-exchanged zeolite X Molecular dynamics... 

For three-letter codes cf. Ref. [235], Note A few abbreviations, as for instance CLIN, are not acronyms (three-letter codes) approved by the Structure Commission of the International Zeolite Association (IZA), but just convenient designations. 

Considering only frameworks made up entirely of tetrahedral comer-sharing TO4 species, full details of all the structure types are collected, refereed and published by the Structure Commission of the International Zeolite Association. The most recent publication indicates that around 170 framework types (each of which is given a unique three-letter code) have been unambiguously identified and both hardcopy publications (in particular the so-called Atlas of Zeolite Framework Types ) and the continuously updated structural summary on the web site (www.iza-structure.org) are indispensable resources for the researcher in this field. 

Zeolites are crystalline microporous materials with uniform pore sizes (<2nm) that find a wide range of applications in many industrially important adsorption, separation, and catalytic processes [89-92]. Traditionally, the term zeolite refers to a crystalline aluminosilicate or silica polymorph based on corner-sharing TO (T = Si and Al) tetrahedra forming a three-dimensional network with uniformly sized pores of molecular dimensions (Figure 3.9). Each material is assigned a three-letter framework structure code by the International Zeolite Association (IZA) [93]. Framework types do not depend on composition, distribution of T-atoms, cell dimensions, or symmetry [1]. 

Zeolites, or molecular sieves, are a group of materials with ordered crystalline lattice structures. Within the framework, regular-shaped pores (or cages) are formed. These pores are interconnected to each other through openings (or windows) of the framework. So far, more than 200 unique types of zeolite structures have been identified. Each of the structures is designated with a three-letter code. Details about the zeolite structures and the related materials can be found at the International Zeolite Association s website [24]. 

The overwhelming richness of structural types can be seen from the fact that there are over 140 recognized zeolite networks (thermally stable and microporous), this number growing by about six every year [2,3]. On the theoretical side there are estimates that the number of plausible regular tetrahedral frameworks exceeds 100 000, f2j and the uninodal nets alone number more than 150 [4]. The lUPAC approved Structure Commission of the International Zeolite Association are in charge of the assignment of three letter codes to each unique zeolite structure and publish them in a web-based database [5J. 

Zeolites are crystalline nanoporous inorganic materials formed by TO tetrahedra (T=Si, Al, P, etc.), which show widespread applications in many industrial processes such as catalysis, adsorption, and separation [1-3]. In the 1940s, Barrer and Milton opened up the avenue to the synthesis of zeolites. Since then, there have been considerable efforts in the synthesis of new zeolite materials. Up to Jun. 2013, 206 types of zeolite materials have been identified by the Structure Commission of the International Zeolite Association (IZA), each of which has been named with a three-letter code [4]. Table 1 presents the new framework types approved since the 16th International Zeolite Conference (IZC-16) in 2010. 

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