This review discusses approaches for tailoring active sites in extra-large pore, nanocrystalline, and hierarchical zeolites and their performance in emerging catalytic applications.

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A novel methodology, called ADOR (assembly-disassembly-organisation-reassembly), for the synthesis of zeolites is reviewed here in detail. The ADOR mechanism stems from the fact that certain chemical weakness against a stimulus may be present in a zeolite framework, which can then be utilized for the preparation of new solids through successive manipulation of the material. In this review, we discuss the critical factors of germanosilicate zeolites required for application of the ADOR protocol and describe the mechanism of hydrolysis, organisation and condensation to form new zeolites starting from zeolite UTL. Last but not least, we discuss the potential of this methodology to form other zeolites and the prospects for future investigations.

zeolites, modification of zeolite acidity for use as fluid catalytic cracking (FCC) catalysts or even for the preparation of novel zeolite frameworks. [1] Considering the significance of zeolite applications at the industrial level, a thorough understanding of zeolite (in)stability under aqueous conditions has been identified as a very important problem in catalysis and zeolite science. Zeolite (in)stability in water or under steaming conditions has been investigated by a number of experimental techniques, in particular magic angle spinning (MAS) NMR, IR, powder X-ray diffraction (PXRD), calorimetry and adsorption. Experimental studies have often been augmented by computational modeling and a large number of relevant theoretical papers can be found in the literature. While the main focus of this review is on reactive interactions of water with zeolites, it is also important to review the most important observations obtained for nonreactive water adsorption in zeolites. It is not surprising that all-silica zeolites, which exhibit negligible water uptake are stable even under conditions where Alcontaining zeolites lose crystallinity: the effective framework hydrolysis can only take place when sufficient water is present in the zeolite channel system. The amount of water inside the zeolite channels depends critically on the concentration of heteroatoms and/or framework defects, such as silanol nests, which show much higher affinity toward water than hydrophobic SiOSi bridges. Zeolite hydrophobicity increases with increasing Si/Al ratio and incomplete pore filling by water is commonly observed for zeolites with high Si/Al at standard pressure. It has been suggested already in the 1950s by Young that water can only adsorb on surface silanol groups, while the parts of the silica surfaces formed by SiOSi bridges are hydrophobic. [2] Both water adsorption in zeolites and zeolite (in)stability under aqueous conditions depend on the zeolite composition (Si/Al ratio, charge-compensating cations, and defect concentration in particular). Our primary goal is to review the most critical aspects of zeolite (in)stability for a broad range of temperature and partial water pressure (p 0), focusing on the framework zeolite composition (Si/Al ratio and presence of Ge, Sn, and Ti heteroatoms) and defect concentration. Zeolites (in)stability in water is discussed for increasing extent of framework degradation, starting from the nonreactive interaction with water, reversible hydrolysis of TO bonds, mild zeolite demetallation, mesopore formation, and total amorphization (Figure 1). Zeolites are among the most environmentally friendly materials produced industrially at the Megaton scale. They find numerous commercial applications, particularly in catalysis, adsorption, and separation. Under ambient conditions aluminosilicate zeolites are stable when exposed to water or water vapor. However, at extreme conditions as high temperature, high water vapor pressure or increased acidity/basicity, their crystalline framework can be destroyed....