Zeolites pollution abatement

Porous materials are of huge practical significance for applications in industry, energy production, and pollution abatement. In this regard, microporous materials, such as zeolites and related materials,... 

To use adsorption as a unitary operation in industrial, pollution abatement, or energy production applications, in most cases, a reactor where a dynamic adsorption process will take place is packed with a concrete adsorbent. The adsorbents generally used for these applications are active carbons, zeolites and related materials, silica, mesoporous molecular sieves, alumina, titanium dioxide, magnesium oxide, clays, and pillared clays. 

CHEMICAL AND POLLUTION ABATEMENT APPLICATIONS OF ION EXCHANGE IN ZEOLITES... 

The book explores various examples of these important materials, including perovskites, zeolites, mesoporous molecular sieves, silica, alumina, active carbons, carbon nanotubes, titanium dioxide, magnesium oxide, clays, pillared clays, hydrotalcites, alkali metal titanates, titanium silicates, polymers, and coordination polymers. It shows how the materials are used in adsorption, ion conduction, ion exchange, gas separation, membrane reactors, catalysts, catalysts supports, sensors, pollution abatement, detergency, animal nourishment, agriculture, and sustainable energy applications. 

The author of this book has been permanently active during his career in the held of materials science, studying diffusion, adsorption, ion exchange, cationic conduction, catalysis and permeation in metals, zeolites, silica, and perovskites. From his experience, the author considers that during the last years, a new held in materials science, that he calls the physical chemistry of materials, which emphasizes the study of materials for chemical, sustainable energy, and pollution abatement applications, has been developed. With regard to this development, the aim of this book is to teach the methods of syntheses and characterization of adsorbents, ion exchangers, cationic conductors, catalysts, and permeable porous and dense materials and their properties and applications. 

POLLUTION ABATEMENT USING ZEOLITES STATE OF THE ART AND FURTHER NEEDS... 

Some issues regarding technological achievements, with or without zeolites, by catalysis for pollution abatment have been reviewed recently (2, 3), as well as an review of the best available technologies for reducing NOx and N2O emissions from industrial activities (4). 

The opening chapter presents the state of the at in zeolite science. The two subsequent chapters summarize the chemistries involved in the processes and the constraints imposed on the catalysts/adsorbents. Three major areas are covered oil refining, petrochemicals and fine chemicals. A chapter on the (curative) use of zeolites in pollution abatement completes this overview. 

FIGURE 11.5 Study of the relation between the flux J and AP, during the transport of H2 and CO2 through a porous ceramic membrane produced by thermal treatment of a natural zeolite. (From Roque-Malherbe, R., Applications of natural zeolites in pollution abatement and industry. In Nalwa, H.S., ed.. Handbook of Surfaces and Interfaces of Materials, Vol. 5, Academic Press, New York, 2001.)... 

Among the various applications of natural zeolites in sectors of technical significance, the use in the control and abatement of environmental pollution is gaining increasing interest all over the world. Copious references on this are found in the introductory plenary lectures of the three International Conferences on natural zeolites held in the last years (1-3) Focusing our attention on the wastawaters pollution abatement, it may be observed that not more than two or three zeolites (clinoptilolite, mordenite and phillipsite) have been considered until now for removal of cationic pollutants from waters, and that the recourse to ion exchange processes has been limited to the treatment of few cations, substantially ammonium, cesium and strontium. Lack of data is found for instance in the literature on the use of natural zeolites for the removal of heavy metals (4-5), even if these are common... 

The application of zeolite catalysts to pollution abatement is also promising. The main pollutants in gaseous emissions that can be potentially treated by zeolites are volatile organic compounds (VOCs) and NOx. 

Finally, the abatement of NO pollution by using sorbing catalytic materials [59,60] must also be cited. Several solid sorbents for NO removal (metal oxides, spinels, perovskites, double-layered cuprates, zeolites, carbonaceous materials, heteropolyacids and supported heteropolyacids) have been tested. The results are interesting, but not competitive to actual technologies. To mention that the use of sorbing materials allows... 

As mentioned by Breck in the introductory lecture, molecular sieve zeolites should find use in various pollution control applications. Both their sorbent and catalytic properties make them technically feasible as agents for various aspects of pollution control and abatement. 

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