Structure Commission of the International Zeolite Association

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. 

Not all frameworks built from tetrahedra as described above are considered to be zeolites. Dense phases are not considered to be zeolites, only those phases with some porosity. Generally, materials with pores accessible by windows defined by six T-atoms or less (six-rings) are not considered to be zeolites. In fact, the boundary between zeolites and dense phases is somewhat nebulous. lUPAC defines [1] zeolites as a subset of microporous or mesoporous materials containing voids arranged in an ordered manner and with a free volume larger than a 0.25 nm diameter sphere. The Structure Commission of the International Zeolite Association uses the criterion of framework density (T-atoms per lOOOA ) with the maximum framework density for zeolites ranging from 19 to 21. 

Published on behalf of the Structure Commission of the International Zeolite Association... 

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. 

Atlas of Zeolite Framework Types. Structure Commission of the International Zeolite Association, 5th Edn, eds Ch. Baerlocher, W.M. Meier, and D.H. Olson, Elsevier, 2001... 

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. 

W. M. Meier and D. H. Olson, Atlas of Zeolite Structure Types, Structure Commission of the International Zeolite Association, 1978 It has recently been demonstrated that the use of synchrotron x-ray sources permits single crystal studies to be carried out on much smaller samples. P. Eisenberger, J. B. Newsam, M. E. Leonowicz, and D. E. W. Vaughan, Nature 309 45 (1984) The use of Rietveld refinement techniques allows better. structural information to be obtained from powder diffraction data. W. I. F. David, W. T. A. Harrison, and M. W. Johnson, in High Resolution Powder Diffraction, Materials Science Forum, vol. 9 (C. R. A. 

The International Zeolite Conference is one of the pillars on which the identity of the zeolite community stands, at the same level of the definitions of zeolite structures provided by the Structure Commission of the International Zeolite Association, the dedicated journal which was Zeolites and is now Microporous and Mesoporous Materials, and the meetings of several national and regional zeolite associations. 

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. 

Source Web of Science (papers) and Derwent Innovation Index (patents), October 2008, used with permission. The inset shows the number of Framework Type Codes (FTCs) collected in the different editions of the Atlas of Zeolite Framework Types plus the number of FTCs already approved by the Structure Commission of the International Zeolite Association in November 2008 (http //www.iza-structure.org/)... 

Zeolites and related microporous materials offer abundant chemical diversity. Over the past three decades, many new synthetic zeolites have been discovered. The Structure Commission of The International Zeolite Association have approved 145 framework types (November 2003). In addition, there are numerous other zeolites with structures that are not yet known or are only hypothetical. The goals of this article are to briefly mention the main categories and principal industrial uses of zeolites, before providing more detailed discussions of molecular sieving and redox reactions. 

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. 

Table 1 lists some important zeolite types with their chemical and structural features. The reported chemical compositions are idealized for simplicity, so actual formulas may be quite different either as regards the Si/Al ratio or, especially, the cationic composition. Structural codes are those set up by the Structure Commission of the International Zeolite Association, following the recommendations of the lUPAC Commission on Zeolite Nomenclature [6]. 

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. 

J The Structure Commission of the International Zeolite Association (IZA-SC), 2005, http //www. iza-structure.ore/. http //www.iza-structure.ore/databases/... 

Table 16.1 Silica-based ((Si) or (Si,AD) microporous materials prepared via the fluoride route in the alphabetic order of their code assigned by the Structure Commission of the International Zeolite Association (SC-IZA) [25]...

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. 

Based on such variations in the framework of zeolites, a structure code has been assigned to each one of them, for the sake of simplicity in their identification. In fact, as many as 191 types of structure codes (i.e.. Framework Type Code, FTC) have been proposed by the Structure Commission of the International Zeolite Association (IZA-SC) [5]. It is notable that several zeolites exhibit similarities in their structures which can be grouped together to form a iso-structural group of zeolites. Table 2.9 represents details of the common groups based on the type of structure of zeohtes [8]. 

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