Membrane Gas-Separation Technology

One unique appHcation 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 appHed to a hoUow-fiber support. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation... 

Gas separation membrane technologies are extensively used in industry. Typical applications include carbon dioxide separation from various gas streams, production of oxygen enriched air, hydrogen recovery from a variety of refinery and petrochemical streams, olefin separation such as ethylene-ethane or propylene-propane mixtures. However, membrane separation methods often do not allow reaching needed levels of performance and selectivity. Polymeric membrane materials with relatively high selectivities used so far show generally low permeabilities, which is referred to as trade-off or upper bound relationship for specific gas pairs [1]. 

Favre, E. et al., COj/Nj reverse selective gas separation membranes Technological opportunities and scientific challenges. Industrial and Engineering Chemistry Research, 2009.48(7) 3700-3701. 

There are current environmentally friendly processes for separation and purification methods by gas separation membrane technologies that are cost-effective for selective applications. Aromatic PAs... 

Most solution-cast composite membranes are prepared by a technique pioneered at UOP (35). In this technique, a polymer solution is cast directly onto the microporous support film. The support film must be clean, defect-free, and very finely microporous, to prevent penetration of the coating solution into the pores. If these conditions are met, the support can be coated with a Hquid layer 50—100 p.m thick, which after evaporation leaves a thin permselective film, 0.5—2 pm thick. This technique was used to form the Monsanto Prism gas separation membranes (6) and at Membrane Technology and Research to form pervaporation and organic vapor—air separation membranes (36,37) (Fig. 16). 

In the 1940s to 1950s, Barrer [2], van Amerongen [3], Stem [4], Meares [5] and others laid the foundation of the modem theories of gas permeation. The solution-diffusion model of gas permeation developed then is still the accepted model for gas transport through membranes. However, despite the availability of interesting polymer materials, membrane fabrication technology was not sufficiently advanced at that time to make useful gas separation membrane systems from these polymers. 

R. Prasad, R.L. Shaner and K.J. Doshi, Comparison of Membranes with Other Gas Separation Technologies, in Polymeric Gas Separation Membranes, D.R. Paul and Y.P. Yampol skii (eds), CRC Press, Boca Raton, FL, pp. 531-614 (1994). 

Kaldis, S.P., Skodras, G. and Sakellaropoulos, G.P. (2004) Energy and capital cost analysis of C02 capture in coal IGCC processes via gas separation membranes. Fuel Processing Technology,... 

Jordal K, Bredesen R, Kvamsdal HM, and Bolland O. Integration of H2-separating membrane technology in gas turbine processes for CO2 capture. Energy 2004 29 1269-1278. 

Prasad R, Shaner L, and Doshi KJ. Comparison of membranes with other gas separation technologies. In Paul DR and YampoTskii YP, eds. Polymeric Gas Separation Membranes. Boca Raton, FL CRC Press, 1994. 

Permeable gas separation membranes utilize differences in solubility and diffusion of different gas components in polymer materials. In recent years membrane-based technologies have gained increasing importance in gas processing. Typical applications are CO2 removal from natural gas or hydrogen recovery from synthesis gas. The degree of selectivity between different gas components depends on the membrane used so that it is necessary to contact the manufacturers for a concrete project. Membrane separation units are usually supplied skid mounted. 

R. Spillman, Economics of gas separation membrane processes, in R.D. Noble and S.A. Stern, (Eds.), Membrane Separation Technology. Elsevier, Amsterdam, 1995, Chap. 13, pp. 589-667. 

H.M. Van Veen, M. Bracht, E. Harmoen, and P.T. Alderliesten, "Feasibility of the Application of Porous Inorganic Gas Separation Membranes in Some Large-Scale Chemical Processes", in Fundamentals of Inorganic Membrane Science and Technology A.J. Burggraaf and L. Cot (Eds), Elsevier Science, 1966. 

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