Separation of supercritical CO2 and iso-octane mixtures with an asymmetric polyimide membrane

Ohya, Haruhiko; Higashijima, Takeshi; Tsuchiya, Y.; Tokunaga, Hitoshi; Negishi, Yoichi

doi:10.1016/0376-7388(93)85060-a

Cited by 19 publications

(9 citation statements)

References 2 publications

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“…Aromatic polyimides have excellent thermal stability at high temperatures under inert atmosphere and have been the extensively investigated membranes in CO 2 separations 14–17. Kapton based membranes have been investigated for the separation of supercritical CO 2 from hydrocarbons18, 19 and He/N 2 , H 2 /N 2 separations at high temperatures 20…”

Section: Introductionmentioning

confidence: 99%

Matrimid polyimide membranes for the separation of carbon dioxide from methane

Sridhar

Veerapur

Patil

et al. 2007

J of Applied Polymer Sci

104

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Three types of polyimide membranes viz., Matrimid, Kapton and P84, were prepared by solution casting and solvent evaporation method to study the permeation of CO 2 and CH 4 gases. Barrier properties were investigated as a function of feed pressure for pure gases and feed composition for the binary mixtures of CO 2 and CH 4 . Kapton polyimide, prepared by imidization of polyamic acid, showed an increase in permeability, but reduction in selectivity, due to the occurrence of plasticization at higher feed CO 2 concentrations. Matrimid was found to exhibit the highest permeability and was studied in greater detail, due to the feasibility in its scale-up into a hollow fiber modular configuration for commercial application. Matrimid was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray diffractometry (XRD) to assess the intermolecular interactions and to understand the separation profiles. The effect of feed flow was evaluated by studying the permeation behavior of flat sheet membrane in dead-end operation mode with the hollow fiber module operated in crossflow feed mode. For pure gases, Matrimid hollow fiber membrane exhibited a CO 2 permeability of 12.7 Barrers with a CO 2 /CH 4 selectivity of 40 at the feed pressure of 20 bar. At the same pressure, for binary mixture feed of 5 mol % CO 2 in methane, the module gave a permeability of 7.4 Barrers with a selectivity of 21. The total binary mixture permeability was determined at the feed CO 2 concentrations varying from 0 to 20 mol % to demonstrate the preferential sorption of CO 2 in Matrimid membrane.

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Section: Introductionmentioning

confidence: 99%

Matrimid polyimide membranes for the separation of carbon dioxide from methane

Sridhar

Veerapur

Patil

et al. 2007

J of Applied Polymer Sci

104

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“…Carbon dioxide is a very effective processing aid for swelling − and plasticizing polymers − to promote the impregnation, extraction, and foaming of polymer films. , Despite these positive aspects, the high pressures required in supercritical applications and the expensive nature of most CO 2 surfactants and stabilizers make the development of processes for high-pressure separations of CO 2 from small molecules important to control operating costs. Polymeric membranes have potential for these types of separations …”

Section: Introductionmentioning

confidence: 99%

Carbon Dioxide-Induced Plasticization of Polyimide Membranes: Pseudo-Equilibrium Relationships of Diffusion, Sorption, and Swelling

et al. 2003

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The application of membranes in gas separation and pervaporation requires materials that are resistant to plasticizing feed streams. We demonstrate the relationship between CO2 sorption, permeability, and film swelling of a polyimide gas separation membrane and how these properties are affected by systematic changes to the polymer structure induced by thermal annealing and covalent cross-linking. Dilation of polyimide thin films (∼120 nm) exposed to high-pressure CO2 (up to 100 atm at 35 °C) was measured by in situ spectroscopic ellipsometry to decouple the effects of thermal and chemical treatments on the film swelling. The refractive index of the CO2-swollen polymer is also used to estimate the CO2 sorption for comparison against that measured on thick films (∼50 μm) by the pressure-decay method. Differences in sorption levels in thin and thick films appear to be related to accelerated physical aging of the thin films. Both thermal annealing and covalent cross-linking of the polyimide films reduce polymer swelling to prevent large increases in the CO2 diffusion coefficient at high feed pressures. The CO2 permeability and polymer free volume strongly depend on the annealing temperature, and different effects are observed for the cross-linked and un-cross-linked membranes. The so-called “plasticization pressure” in permeation experiments (i.e., upturn in the permeation isotherm) appears to correlate with a sorbed CO2 partial molar volume of 29 ± 2 cm3/mol in the polymer. Furthermore, cross-linking of high glass transition polyimides produces a much greater reduction of the CO2-induced dilation than does cross-linking of rubbery polymers such as PDMS for swelling up to 25%.

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“…In the interest of clarity, this concept is depicted as a two-step process; however, it is important to note that the steps actually occur concurrently. 20 years (Afrane and Chimowitz, 1996;Chiu and Tan, 2001;Higashijima et al, 1994;Kulcke, 2001;Nakamura et al, 1993;Ohya et al, 1993;Sarrade et al, 2001;Semenova et al, 1992b). Much of the emphasis has been on ultrafiltration or nanofiltration membranes, which are either used in dense form or supported by a ceramic support.…”

Section: Introductionmentioning

confidence: 99%

“Sorp‐vection”: An unusual membrane‐based separation

Damle

Koros

2005

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com). A nonstandard membrane process is described that involves highly selective sorption of a compound "A" at a large absolute weight fraction A , coupled with a significant diffusionally induced flux of a second component "B." The flux of B convectively moves A from a dilute external mass fraction relative to component B upstream to an enriched mass fraction downstream. The general form of the process has potential applications involving dilute feeds where current membranes processes perform poorly for such removal as a result of excessive solubility of the smaller component B. The most important IntroductionSeparations of condensables from effluent streams can be achieved by low-temperature condensation or pressure swing adsorption. These technologies have the disadvantage that they are energy intensive and tend to have large footprints. Membranes, on the other hand, are compact, simple to operate, and economical. Development of membranes for separation of condensable components from effluent streams is being pursued and provides a potentially attractive separation avenue (Baker et al., 2002(Baker et al., , 1994(Baker et al., , 1998. If properly supported against mechanical deformation, polymer membranes can be used to separate dilute concentrations of highly condensable bulky components from smaller, less condensable components such as air. The highly condensable nature of heavier and polar hydrocarbons tends to make them sorb easily into rubbery or glassy polymers, whereas highly supercritical components such as N 2 exhibit low sorption uptakes, even at relatively high pressures of 10 bars or so (Mark et al., 1984). On the other hand, for rubbery polymers, the intrinsically higher diffusion coefficient for smaller vs. larger molecules tends to be much less extreme than that in glassy materials. Therefore, rubbery polymers are the preferred materials for such solubility-based separations where the sorption level of the small molecule is sufficiently low. An increasingly important class of systems, however, constitutes a sufficiently high intrinsic sorption coefficient that may prevent effective application of this simple solubility-controlled sorption-diffusion permeation mechanism of separation. This type of application is the focus of this article.Separations involving supercritical carbon dioxide are of great interest, and development of CO 2 technology for use in industrial processing has become a research focal point. Worldwide, billions of pounds of organic solvents are used as processing tools, cleaning agents, and dispersants. Concern for workers' safety and a drive to protect the environment have prompted industrial and academic research efforts to develop acceptable solvent alternatives (DeSimone 1998 and has a broad range of dissolving power, especially in the supercritical region (Kazarian et al., 1999;McHugh and Krukonis, 1986). For the CO 2 to be recycled and reused in processing applications, separation of the CO 2 from bulkier organic solutes wil...

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Separation of supercritical CO2 and iso-octane mixtures with an asymmetric polyimide membrane

Cited by 19 publications

References 2 publications

Matrimid polyimide membranes for the separation of carbon dioxide from methane

Matrimid polyimide membranes for the separation of carbon dioxide from methane

Carbon Dioxide-Induced Plasticization of Polyimide Membranes: Pseudo-Equilibrium Relationships of Diffusion, Sorption, and Swelling

“Sorp‐vection”: An unusual membrane‐based separation

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