Zeolite future trends

The types of shape selective catalysis that occur in zeolites and molecular sieves are reviewed. Specifically, primary and secondary acid catalyzed shape selectivity and encapsulated metal ion and zero valent metal particle catalyzed shape selectivity are discussed. Future trends in shape selective catalysis, such as the use of large pore zeolites and electro- and photo-chemically driven reactions, are outlined. Finally, the possibility of using zeolites as chiral shape selective catalysts is discussed. 

In this paper, we review primary and secondary shape selective acid catalysis with zeolites. Next, we discuss shape selectivity with metal containing zeolites.We conclude with a section that deals with future trends in shape selective catalysis. 

All these aspects were thoroughly discussed by lecturers and participants during the round table organized during the Poitiers School on The Future Trends in Zeolite Applications . Special emphasis was placed on the role played by the sites at the external surface (pockets, etc.) or at the pore mouth, by mesopores, extraframework aluminum species, as well as by the polarity of reactant and product molecules. Other important topics dealt with the remarkable catalytic properties of BEA zeolites for fine chemical synthesis, the potential of mesoporous molecular sieves, zeolitic membranes and the role of combinatorial catalysis in the development of zeolite catalysts. It is our hope that the fruits of these discussions will appear in the literature or even better as new and environmentally friendly products or processes. 

Since the membranes incorporated in MMRs are zeolite or dense metal ones, which have been described extensively in previous chapters, this chapter focuses mainly on the general structure, design, and fabrication of MMRs and their applications. The recent advances and future trends of MMR technology are also given. 

Since 2001, the zeolite catalysis made a leap-frog jump after the introduction of mesoporous materials, metal-organic frameworks, and hierarchical systems, as well as after the turnaround in the paradigm in technologies and feedstock availability and future trends. 

This contribution briefly highlights current trends in the synthesis of new types of zeolite-based molecular sieves showing recent development in this very topical area. We have tried to cover the most important examples of the development of these molecular sieves, in which a high potential for future applications of molecular sieves is expected. At the end of... 

When the ethanol is not blended but used as such as fuel, hydrous ethanol (e.g. 95%) can be applied. In a cascade-type continuous set-up [27] a partial evaporation of the fermentation liquid was carried out and the ethanol-water mixture was passed over a H-ZSM5 zeolite (350 °C, 1 atm). As in the MTG (methanol to gasoline) [28, 29] process a mixture of alkanes (mainly C3-C5) and aromatics (mainly toluene, xylenes and C<)-compounds) was obtained. In this approach the ethanol-water separation is avoided the hydrocarbons and water are non-miscible and separate by gravity. Though its octane number is good there is no future in MTG-gasoline because of the trend to lower the aromatics content. 

Thus the statistical pattern is governed by the political development in Eastern Europe. During the cold war East European countries had no excess to the major producers of synthetic zeolites thus they developed technologies to use their abundant natural deposits for catalytic applications. The disintegration of the Soviet Union, accompanied by a political and economic crisis, led to a decrease of research activity in this field. The slight recovery of this trend in recent time is associated with an increased number of English papers written by East Europeans (lift of the iron curtain). One may extrapolate that in the future natural zeolites will become less important for catalytic applications. 

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