International Zeolite Association

BaerlocherC, McCuskerLB. International Zeolite Association Database of Zeolite Structures, http //www.iza-online.org/... 

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 12-MR pores in the CIT-1 structure [International Zeolite Association (IZA) structure code, CON] are 6.8 x 6.4 A in diameter while the intersecting 10-MR pores are5.1x5.lA.B oth pore dimensions might be regarded as small for the ring size but interestingly molecular simulation of the pores between 0 and 200 K indicate the 10-MR pores can flex by >1 A (25). The potential catalytic activity of... 

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. 

Meier, W. M., and Olson, D. H., Atlas of Zeolite Structure Types." International Zeolite Association, Zurich, 1978. 

A number of conferences have now been held whose focus has been molecular sieve zeolites. The International Zeolite Association will have held the Fifth International Conference on Zeolites in Naples in June, 1980. The first such conference was organized by R. M. Barrer in London in 1967, and was followed by others in Worcester, Massachusetts in 1970, Zurich in 1973, and Chicago in 1977. Preceding these were the All-Union Conferences held in the USSR in 1961 and 1964 other European conferences have included the First All-Union Conference - on Molecular Sieves in Catalysis held in Novosibirsk in 1976, the Symposium on Zeolites held in Szeged, Hungary in 1978, and the Symposium on Catalysis by... 

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

R. Roque-Malherbe, L. Lemes, M. Autie, and O. Herrera, 8th International Zeolite Conference Extended Abstracts, J.C. Jansen, L. Moscou, and M.F.M. Post, (editors), International Zeolite Association, Amsterdam, the Netherlands, 1988, p. 137. 

Dr. Rolison is a member of the American Chemical Society, AAAS, the International Zeolite Association, the Materials Research Society, and the Society for Electroanalytical Chemistry (SEAC). She wrote Ultramicroelectrodes, the first textbook in this very active research area of electrochemistry, with Martin Fleischmann, Stanley Pons, and Peter Schmidt. She and Henry White guest-edited an issue of Langmuir devoted to the electrochemistry of nanostructured materials (February 1999). Dr. Rolison was a member of the Advisory Board for Analytical Chemistry and is a current member of the editorial boards of the Journal of Electroanalytical Chemistry and Langmuir. She is a member of the Board of Directors for the SEAC and has served since 1997 as editor of the society s newsletter, SEAC Communications. 

The disproportionation of ethylbenzene (EB) to benzene (B) and diethylbenzenes (DEB) serves as a case study. This reaction has been introduced by Karge et al. and Weitkamp et al. to compare the activity of different zeolite catalysts [58, 59], and to distinguish between medium- and large-pore zeolites [112, 60], Moreover, since 1994, it has been further developed as a standardized test reaction by the International Zeolite Association (IZA) [55], A general representation of the individual transformations which occur in this type of reaction, is given in the following scheme ... 

Breck s preparation of type Y faujasite in die late 1950 s still stands as the outstanding success in zeolite synthesis (2). Type X might have had some catalytic applications but I doubt the International Zeolite Association would exist without the interest and support generated by the catalytic applications of the Type Y materials. It didn t seem that critical at the time after all Breck had reproduced a material which exists naturally. Synthetic counterparts of natural zeolites have been prepared dozens of times since (3). But die extra silica content, or perhaps die diminished alumina content, was enough to give high temperature stability in the acid form and to get zeolites into catalysts for petroleum processes (4). 

A great part of the success of the symposium on zeolite synthesis can be attributed to the generous contributions from several industrial sponsors and to the support of the Division of Colloid and Surface Chemistry of the American Chemical Society and of the International Zeolite Association. A special acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for the support provided during the early stages of this project... 

Atlas of Zeolite Structure Types (1992) Atlas of Zeolite Structure Types (W.M. Meier and D.H. Olson, eds), International Zeolite Association, Butterworth-Heinemann, London. 

A complete list of zeolites is provided by the Atlas of Zeolites, published by 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. 

Figure 2.12 Plot of the area per T-atom vertex SI) versus the average ring size, n, for a variety of zeolites, silica clathrasils and dense silicates. (All zeolites have a silicon aluminium ratio exceeding three, so that the approximate stoichiometry of all these frameworks is Si02). Zeolite and clathrasil frameworks are labelled by the code adopted by the International Zeolite Association [18]). The shaded domain indicates the window of geometrically accessible values of as a function of the ring size. Despite the allowed geometric variability, the value of D is close to 12.2A2 for all these "silicates", regardless of the ring size and consequent intrinsic curvature.

Petrovic et al. (1993) reported seven high-silica zeolite structures (ATI, EMT, FAU, FER, MEL, MFI, and MTW, topologies in standard International Zeolite Association nomenclature) to be 5.6-14.3 kJ/mol less energetically stable than a-quartz. Navrotsky et al. (1995) reported the enthalpy of MEI was 13.9 0.4 kJ/mol higher than that of a-quartz. Piccione et al. (2000) found eleven high-silica zeolite structures (AST, BEA, CFI, CHA, IFR, ISV, ITE, MEL, MFI, MWW, and SST) to be 6.0-15.5 kJ/mol less stable in enthalpy than a-quartz. 

IZA (International Zeolite Association) zeolite database is maintained by IZA structure commission. Available on-line at http //www.iza-structure.org/databases/. 

Verified Synthesis of Zeolite Materials, ed. H. Robson, 2nd Edn, Elsevier Synthesis Commission of the International Zeolite Association, Amsterdam, 2001. 

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