Olefin/Paraffin Separation through Carbonized Membranes Derived from an Asymmetric Polyimide Hollow Fiber Membrane

Okamoto, Ken‐ichi; Kawamura, Shigeo; Yoshino, Makoto; Kita, Hidetoshi; Hirayama, Yusuke; Tanihara, Nozomu; Kusuki, Yoshihiro

doi:10.1021/ie990209p

Cited by 135 publications

(82 citation statements)

References 26 publications

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“…Moreover, as compared to polymeric materials, carbonized membranes have higher tolerance to harsh environments due to the sluggish chemical reactivity and better thermal resistance. The microstructure of carbon membranes from polyimides is determined by a number of factors including: (1) the different chemical structure of polyimides which induces dissimilar chain packing, thermal stability, molecular flatness and in-plane orientation [27,28]; (2) the pyrolysis conditions such as temperature, atmosphere and heating rate [29,30]; (3) the pre-treatment of polyimide before carbonization using thermostabilization, polymer blending, nonsolvent immersion or chemically grafted side groups [31][32][33][34][35][36][37]; (4) post-treatment of carbonized membranes by oxidation or chemical vapor deposition [38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, cross-linking and carbonization of co-polyimides containing internal acetylene units for gas separation

Xiao

Chung

Guan

et al. 2007

Journal of Membrane Science

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Cross-linkable polyimides containing internal acetylene units have been synthesized by random copolymerization of 6FDA dianhydride, 2,3,5,6-tetramethyl-1,4-phenylenediamine (Durene) and 4,4 ′ -diaminodiphenylacetylene (p-intA) diamine as materials for gas separation. Compared with 6FDA-Durene polyimide, 6FDA-Durene/p-intA co-polyimide shows denser polymer chain packing, which is confirmed by wide-angle X-ray diffraction (WAXD). The thermally treated co-polyimides are insoluble in various solvents and show an increase in T g , indicating the formation of network structures among the polymer chains. Differential scanning calorimetry (DSC) and FT-Raman suggest that cross-linking arises from Diels-Alder cycloaddition between the internally arranged acetylene units along the polymer main chain, resulting in extended conjugated aromatic structures. The thermally cross-linked membranes show enhanced resistance to CO 2 plasticization up to around 5 × 10 6 Pa (700 psi). The rigidified membrane structure provides increased gas selectivity without severely compromising gas permeability. The gas separation performance of carbonized membranes is remarkably superior to those of neat and cross-linked copolyimides because of a large increase in rigidification in the polymer matrix. A Diels-Alder cycloaddition reaction produces a much more rigid and planar conjugated aromatic structure in the polymer chains and results in a higher degree of graphitization during carbonization, which is confirmed by XPS and WAXD. Carbon membranes derived from co-polyimides with more internal acetylene units show much better gas separation performance than those derived from polyimides without internal acetylene units.

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Section: Introductionmentioning

confidence: 99%

Synthesis, cross-linking and carbonization of co-polyimides containing internal acetylene units for gas separation

Xiao

Chung

Guan

et al. 2007

Journal of Membrane Science

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“…CMSMs compare favorably with their polymer precursors by exhibiting intensive gas transport properties. It can achieve higher selectivity without loosing the productivity [2][3][4][5][6][7][8][9] and thus surpass the upper bound limit of polymeric membranes. CMSMs have also been recognized with advantages of higher thermal and chemical stability [2,[9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…Many studies have reported that a CMSM with tailored microstructure (pore size, pore volume, etc.) could be obtained by controlling the pyrolysis conditions [2,6,9,13,15,[17][18][19] and post-/pre-treatment conditions [7,10,[20][21][22][23][24]. On the other hand, CMSMs can be modified to improve their permeation properties or to solve several problems inherent to their structures.…”

Section: Introductionmentioning

confidence: 99%

“…They showed that the thermostabilization process strengthens the structure of the precursors in order to withstand the high temperatures during pyrolysis. After that, several researches such as Tanihara et al [8], Okamoto et al [7] as well as David and Ismail [12] have also applied thermostabilization in their studies. To our best knowledge, no investigations have been done on chemical modification and solvent treatment of polymer precursors before pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

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Novel approaches to fabricate carbon molecular sieve membranes based on chemical modified and solvent treated polyimides

Tin

Chung

Kawi

et al. 2004

Microporous and Mesoporous Materials

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Novel approaches to fabricate carbon molecular sieve membranes based on chemical modified and solvent treated polyimides Tin, P.; Chung, T-S.; Kawi, S.; Guiver, Michael AbstractTwo brand-new modification technologies were developed for pyrolyzing the carbon molecular sieve membranes (CMSMs) with excellent separation efficiency. The modifications were performed on polymeric precursors. It is believed that the space filling effect by these modifications could considerably alter the separation performance of resultant carbon membranes. Firstly, a cross-linking modification was performed on polymeric precursors at room temperature before pyrolysis. The effectiveness of chemical crosslinking technology in improving gas separation capability of CMSMs was investigated. In this study, the permeation properties of carbon membranes derived from cross-linked Matrimid were characterized as a function of cross-linking density. Results demonstrated that the permeability of modified CMSMs decreased with increasing in cross-linking density. Detailed examination reveals that cross-linking modification increased the selectivity at a low degree of cross-linking but reduced the selectivity at a higher degree of cross-linking. The improvement of separation efficiency at low degree of cross-linking is presumably related to the swelling of polymer chains by methanol during cross-linking modification. Consequently, the second extremely simple modification method by using pure methanol immersion was developed. It was found that the CMSMs derived from methanol-treated precursors exhibited superior transport properties. Methanol treatment yielded CMSMs with higher selectivities if compared to CMSMs based on untreated and cross-linked Matrimid. Therefore, it can be concluded that the swelling of polymer chains by methanol appears to be an effectual modification method to produce the CMSMs with excellent separation properties.

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“…So far, microporous silica membranes have been prepared by sol-gel (Asaeda and Kitao, 1991) and CVD (Tsapatsis et al, 1991) techniques. Further, microporous carbon membranes have been prepared by the carbonization of various types of precursors such as phenol resin (Kita et al, 1997;Centeno and Fuertes, 1999;Fuertes, 2001;Zhou et al, 2001), polyfurfuryl alcohol (Shiflett and Foley, 2001) and polyimide resin (Jones and Koros, 1994;Haraya, 1995, 1997;Hayashi et al, 1997;Peterson et al, 1997;Fuertes and Centeno, 1998;Okamoto et al, 1999). These membranes showed higher selectivity than organic polymer membranes (Nakagawa, 1985) for the gas separations mentioned above.…”

Section: Introductionmentioning

confidence: 99%

Partially Carbonized Polyimide Membranes with High Permeability for Air Separation.

Nishiyama

Momose

Egashira

et al. 2003

J. Chem. Eng. Japan / JCEJ

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Partially carbonized polyimide (CPI) membranes were prepared from a solution of 30 wt% polyamic acid in N,N-dimethylacetamide. The polymer membranes formed on an alumina support were thermally treated, involving imidization in air at 180°C and carbonization in N 2 at relatively low temperature (400-500°C). The cross-sectional views of the supported CPI membranes show that the membranes consist of a top layer (thickness, 10 µ µ µ µ µm) on the support and a CPI/alumina thin layer in the support. The CPI membranes carbonized at 500°C showed high permeability for O 2 of 1000-30000 barrer and permselectivity for O 2 /N 2 of 3-6. The permeability of the CPI membranes was much higher than that of the reported polymer membranes and the carbon membranes. The pores formed under carbonization at 500°C and 400°C were effective for separating O 2 /N 2 and CO 2 /CH 4 mixtures, respectively. TG analysis indicated that the carbonization proceeds even at a constant temperature of 500°C. The successive generation of flexible pores before the formation of graphite structure with rigid pores seems to contribute to the higher permeability of the CPI membranes.

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Olefin/Paraffin Separation through Carbonized Membranes Derived from an Asymmetric Polyimide Hollow Fiber Membrane

Cited by 135 publications

References 26 publications

Synthesis, cross-linking and carbonization of co-polyimides containing internal acetylene units for gas separation

Synthesis, cross-linking and carbonization of co-polyimides containing internal acetylene units for gas separation

Novel approaches to fabricate carbon molecular sieve membranes based on chemical modified and solvent treated polyimides

Partially Carbonized Polyimide Membranes with High Permeability for Air Separation.

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