Zeolite chemistry industrial processes

As documented in Chapter 5, zeolites are very powerful adsorbents used to separate many products from industrial process steams. In many cases, adsorption is the only separation tool when other conventional separation techniques such as distillation, extraction, membranes, crystallization and absorption are not applicable. For example, adsorption is the only process that can separate a mixture of C10-C14 olefins from a mixture of C10-C14 hydrocarbons. It has also been found that in certain processes, adsorption has many technological and economical advantages over conventional processes. This was seen, for example, when the separation of m-xylene from other Cg-aromatics by the HF-BF3 extraction process was replaced by adsorption using the UOP MX Sorbex process. Although zeolite separations have many advantages, there are some disadvantages such as complexity in the separation chemistry and the need to recover and recycle desorbents. 

Wanting to choose a single chemical system, somehow representative or inorganic chemistry, for our cover, we have picked a zeolite. The term may not be familiar to you However, one or more zeolites are almost certainly to be found in every chemical research laboratory, in your home, and in many major industrial processes. They, themselves, are the subject of chemical research from structural determinations to catalysis to the inorganic chemical aspects or nutrition. 

To the author s knowledge, there are at present no major industrial processes which could be strictly defined as nonacid catalysis that make use of zeolite-based catalysts. This is in contrast to acid catalysis where zeolites continue to make an impact. Technically, a number of zeolite-based catalysts for reactions, such as Wacker chemistry and olefin or diolefin oligomerization reactions, appear to be quite attractive, and it is almost certainly economic factors that have limited further development. 

A. P. Bolton, Hydrocracking, Isomerization, and Other Industrial Processes, in Zeolite Chemistry and Catalysis, J. A. Rabo, ed., Monograph 171 (Washington, DC American Chemical Society, 1976). 

Whereas the appropriate forms of zeolites and related solids are widely used in acid-catalysed industrial processes, microporous solids are not currently of importance in commercial base-catalysed conversions. Instead, high-surface-area forms of alkali metal and alkaline earth metal oxides and hydroxides, often supported on alumina, fulfil the need for solid base catalysts. Nevertheless, interest remains in characterising basic sites in cationic zeolites and in developing routes to more strongly basic sites in microporous solids." Routes to the latter include the introduction of metallic forms of alkali metals or nanoparticles of metal oxides and the partial replacement of amine groups at the sites of framework oxygen atoms. Porous solid bases have been shown to exhibit a varied catalytic chemistry, particularly for reactions such as dehydrogenations,... 

Intensive research on zeolites, during the past thirty years, has resulted in a deep understanding of their chemistry and in a true zeolite science, including synthesis, structure, chemical and physical properties, and catalysis. These studies are the basis for the development and growth of several industrial processes applying zeolites for selective sorption, separation, and catalysis. 

Inoue, T., Nagase, T., Hasegawa, Y., Kiyozumi, Y., Sato, K., Nishioka, M., et al. (2007). Stoichiometric ester condensation reaction processes by pervaporative water removal via acid-tolerant zeolite membranes. Industrial Engineering Chemistry Research, 46,3743—3750. 

Yang, J., Lee, C.-H., Chang, J.-W., 1997. Separation of hydrogen mixtures by a two-bed pressure swing adsorption process using zeolite 5A. Industrial Engineering Chemistry Research 36 (7), 2789-2798. 

This is the first book to offer a practical overview of zeolites and their commercial applications. Each chapter is written by a globally recognized and acclaimed leader in the field. The book is organized into three parts. The first part discusses the history and chemistry of zeolites, the second part focuses on separation processes and the third part explores zeolites in the field of catalysis. AH three parts are tied together by their focus on the unique properties of zeolites that allow them to function in different capabilities as an adsorbent, a membrane and a catalyst. Each of the chapters also discusses the impact of zeolites within the industry. 

Processes with liquid-phase reactants dominate in a large part of the chemical industry, in particular in fine chemicals manufacture. A good example of fhe applicafion of acidic cafalysts in fine chemistry is work done by Beers et al. (179,180,200). They prepared (3-zeolite-containing monolithic catalysts and evaluated them in an acylation reaction. The dipcoating technique gave satisfactory results, in particular for silica monoliths. 

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