Zeolite zeotypes

Zeolite/zeotype Structure type code No. of tetrahedra in ring Window diameter (pm) Cavity diameter (pm)... 

Zeolites, ZEOTYPES AND MESOPOROUS SOLIDS SYNTHETIC ASPECTS. 1... 

Chapter 1 is a general overview of zeolite, zeotype and mesoporous solids chemistry, including their design, synthesis and general catalytic properties. Chapter 2 deals with the problems and pitfalls that may occur in the applications of zeolites and other microporous and mesoporous solids to fine chemical synthesis. The remaining chapters deal with specific applications of these catalysts to fine chemical synthesis. 

The framework metal-containing zeotype materials that are the focus of this review do not contain aluminum and thus do not classify as zeolites. Zeotype materials are characterized by properties that make them alike to... 

Table 1 Zeolites, zeotypes, and mesoporous moleeular sieves, selected examples, and their characteristic features...

Based on the lUPAC nomenclature, microporous molecular sieves have pores with dimensions up to 2.0 nm in dimension. The mesopore dimension is between 2.0 and 50 nm, while macropores exhibit pores larger than 50 nm. Shown in Fig. 2 are the pore size and schematic structure of several zeolites, zeotypes, and mesoporous molecular sieves. Evidently, a large number of different zeolite or zeotype structures and mesoporous materials are available from which the optimum one for the given application can be selected. 

Fig. 2 Several zeolites, zeotypes, and mesoporous molecular sieves with dimensions rf Iheir channels...

The continuous effort of numerous laboratories around the world resulted in the last decades in the synthesis of a number of new zeolites, zeotypes, and mesoporous molecular sieves of different chemical compositions. Hand in hand with the success of basic research in this area, zeolites found new industrial applications. 

The diversity of ordered porous solids increases at an astonishing rate, particularly among the readily crystallised MOFs, and continues to olfer novel materials properties. There is no obvious barrier to the synthesis of a myriad of new zeolite, zeotype or hybrid structures. Challenges remain, however. For zeolitic aluminosilicates, the 10 A pore size restriction remains an important barrier, and an enantiomerically pure zeolite is still out of reach. For nonsilicate crystalline microporous solids, thermal and hydrothermal stability, rather than framework geometry, limit their applicability, since fully crystalline germanates and carboxylates with pores in the mesoporous range now exist, and these solids have enormous specific surface areas. In these hybrid solids the ability to choose chirality in the building units indicates that it will be possible to prepare these in chiral form the first examples have already been prepared. 

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