Gas separation membrane applications

Figure 14.5 Monomers Used in Gas Separation Membrane Applications...

Figure 14.8 Monomers used in gas separation membrane applications [76].

The development of this coating technique has enabled the study of ultra-thin films with thicknesses that are of interest in gas separation membrane applications. Figure 3.4(a) presents the influence of aging time on the oxygen permeability coefficients of Matrimid films down to 18 nm in thickness prepared with the coating technique. Note that the quoted film thickness is the thickness of the glassy layer. 

Camacho-Zuniga, C. Ruiz-Trevino, F. A. Hernandez-Lopez, S. Zolotukhin, M. G. Maurer, F. and A. Gonzalez-Montie, A., Aromatic polysulfone copolymers for gas separation membrane applications, J. Membr. Sci., 340(1-2), 221-226 (2009). 

Leading Examples These apphcations are commercial, some on a very large scale. They illustrate the range of application for gas-separation membranes. Unless otherwise specified, all use polymeric membranes. 

In gas separation with membranes, a gas mixture at an elevated pressure is passed across the surface of a membrane that is selectively permeable to one component of the mixture. The basic process is illustrated in Figure 16.4. Major current applications of gas separation membranes include the separation of hydrogen from nitrogen, argon and methane in ammonia plants the production of nitrogen from ah and the separation of carbon dioxide from methane in natural gas operations. Membrane gas separation is an area of considerable research interest and the number of applications is expanding rapidly. 

Recently, as a further recognition of the importance of multiphase copolymers in specialty applications, siloxane containing block and segmented copolymers have received special attention for applications such as biomaterials, photoresists, gas separation membranes, protective coatings, elastomers and emulsifiers, as we shall... 

Selective gas permeation has been known for generations, and the early use of palladium silver-alloy membranes achieved sporadic industrial use. Gas separation on a massive scale was used to separate U from U using porous (Knudsen flow) membranes. An upgrade of the membranes at Oak Ridge cost 1.5 billion. Polymeric membranes became economically viable about 1980, introducing the modern era of gas-separation membranes. H2 recovery was the first major application, followed quickly by acid gas separation (CO2/CH4) and the production of N2 from air. 

Gas separation membranes, conducting polymer applications, 7 539 Gas-solid chromatography, adsorption,... 

Much attention has been paid to the synthesis of fluorine-containing condensation polymers because of their unique properties (43) and different classes of polymers including polyethers, polyesters, polycarbonates, polyamides, polyurethanes, polyimides, polybenzimidazoles, and epoxy prepolymers containing pendent or backbone-incorporated bis-trifluoromethyl groups have been developed. These polymers exhibit promise as film formers, gas separation membranes, seals, soluble polymers, coatings, adhesives, and in other high temperature applications (103,104). Such polymers show increased solubility, glass-transition temperature, flame resistance, thermal stability, oxidation and environmental stability, decreased color, crystallinity, dielectric constant, and water absorption. 

Several classes of polymers containing the HFIP-O group have been reported. These polymers show promise as film formers, gas separation membranes, coatings, seals, and other high temperature applications due to the properties imparted by this function, similar in many ways to the HFIP group. 

One unique application area for PSF is in membrane separation uses. Asymmetric PSF membranes are used in ultrafiltration, reverse osmosis, and ambulatory hemodialysis (artificial kidney) units. Gas-separation membrane technology was developed in the 1970s based on a polysulfone coating applied to a hollow-fiber support. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation... 

From 1943 to 1945, Graham s law of diffusion was exploited for the first time, to separate U235F6 from U238F6 as part of the Manhattan project. Finely microporous metal membranes were used. The separation plant, constructed in Knoxville, Tennessee, represented the first large-scale use of gas separation membranes and remained the world s largest membrane separation plant for the next 40 years. However, this application was unique and so secret that it had essentially no impact on the long-term development of gas separation. 

---