Since the invention of synthetic zeolites in 1959, innovations in sorbent devel-opment and adsorption process cycles have made adsorption a key separationstool in the chemical, petrochemical and pharmaceutical industries. In all futureenergy and environmental technologies, adsorption will likely play either a keyor a limiting role. Some examples are hydrogen storage and CO removal (fromhydrogen, to <1 ppm) for fuel cell technology, desulfurization of transportationfuels, and technologies for meeting higher standards on air and water pollutants.These needs cannot be fulfilled by current commercial sorbents.
The past two decades have shown an explosion in the development of newnanoporous materials: mesoporous molecular sieves, zeolites, pillared clays, sol-gel-derived metal oxides, and new carbon materials (carbon molecular sieves, super-activated carbon, activated carbon fibers, carbon nanotubes, and graphite nanofibers). The adsorption properties for most of these new materials remain largely unexplored.
This book provides a single and comprehensive source of knowledge for all commercial and new sorbent materials. It presents the fundamental principles for their syntheses and their adsorption properties as well as their present and potential applications for separation and purification.
Chapter 2 provides a simple formula for calculating the basic forces or potentials for adsorption. Thus, one can compare the adsorption potentials of two different molecules on the same site, or that of the same molecule on two different sites. The calculation of pore size distribution from a single adsorption isotherm is shown in Chapter 4. The effects of pore size and shape on adsorption are discussed in both Chapters 2 and 4. Chapter 3 aims to provide rules for sorbent selection. Sorbent selection is a complex problem because it also depends on the adsorption cycle and the form of sorbent (e.g., granules, powder, or monolith) that are to be used. The attributes sought in a sorbent are capacity, selectivity, regenerability, kinetics, and cost. Hence, Chapter 3 also includes a summary of equilibrium isotherms, diffusion steps, and cyclic processes. Simple sorbent selection criteria are also presented.
The fundamental principles for syntheses/preparation, adsorption properties, and applications of the commercially available sorbents are covered in Chapters 5–7. Mesoporous molecular sieves are discussed, along with zeolites, in Chapter 7. The sorbent that forms a π-complexation bond with molecules of a targeted component in a mixture is named π-complexation sorbent. The π-complexation bond is a type of weak and reversible chemical bond, the same type that binds oxygen to hemoglobin in our blood. This type of sorbent has been developed in the past decade, largely in the author’s laboratory. Because they have shown a tremendous potential for a number of important applications in separation and purification, they are discussed separately in Chapter 8. This chapter also presents their applications for olefin/paraffin separations, olefin purification (by removal of dienes to <1 ppm, separation of CO, as well as aromatics from aliphatics. The particularly promising application of π-complexation sorbents for sulfur removal from transportation fuels (gasoline, diesel, and jet fuels) is discussed in Chapter 10.
Chapter 9 covers carbon nanotubes, pillared clays, and polymeric resins. Poly-meric resins are in widespread use for ion exchange, water treatment, and ana-lytical chromatography.
In Chapter 10, sorbents for specific applications in separation and purification are discussed in detail. These include both well-established applications, such as air separation, and potential applications, such as gasoline desulfurization and energy storage (of hydrogen or methane).
Tác giả: Ralph T. Yang
