Correlation of separation factor versus permeability for polymeric membranes

Robeson, Lloyd M.

doi:10.1016/0376-7388(91)80060-j

Cited by 3,114 publications

(1,910 citation statements)

References 41 publications

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“…In most membrane research, the relative performance of a material is estimated from a Robeson plot, which gives the relationship between permeability and the permeation selectivity. 27 In all cases, the permeation selectivity value less than one indicates that the membrane is selective but the CO 2 ends up in the retentate. Figure 2a,b shows the zeolite Robeson plots for CO 2 /N 2 , and Figure 2c,d shows those for CO 2 /CH 4 separations.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

Kim

Abouelnasr²,

Lin³

et al. 2013

J. Am. Chem. Soc.

114

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ABSTRACT:We have conducted large-scale screening of zeolite materials for CO 2 /CH 4 and CO 2 /N 2 membrane separation applications using the free energy landscape of the guest molecules inside these porous materials. We show how advanced molecular simulations can be integrated with the design of a simple separation process to arrive at a metric to rank performance of over 87 000 different zeolite structures, including the known IZA zeolite structures. Our novel, efficient algorithm using graphics processing units can accurately characterize both the adsorption and diffusion properties of a given structure in just a few seconds and accordingly find a set of optimal structures for different desired purity of separated gases from a large database of porous materials in reasonable wall time. Our analysis reveals that the optimal structures for separations usually consist of channels with adsorption sites spread relatively uniformly across the entire channel such that they feature well-balanced CO 2 adsorption and diffusion properties. Our screening also shows that the top structures in the predicted zeolite database outperform the best known zeolite by a factor of 4−7. Finally, we have identified a completely different optimal set of zeolite structures that are suitable for an inverse process, in which the CO 2 is retained while CH 4 or N 2 is passed through a membrane. ■ INTRODUCTIONElevated CO 2 concentrations in the atmosphere are considered to be the primary cause of global warming. 1 Because of the ever-increasing amount of CO 2 emissions and our continuing reliance on fossil fuels, it remains imperative to search for various methods to mitigate the emission process. Among many suggested solutions, carbon capture and sequestration (CCS) is emerging as a viable technique: 2 CCS consists of utilizing materials to capture CO 2 emissions from point sources such as electric power plants, cement and steel plants, or natural gas field and injecting the adsorbed CO 2 molecules to geological reservoirs. Some of the main barriers for the large-scale implementation of CCS are the energy requirements and cost of the capture process.The currently available technology uses amines to selectively absorb CO 2 . These amines are very efficient in absorption of CO 2 , but the regeneration of the amine solution is relatively energy intensive. Alternative technologies, such as adsorption by adsorbents 3 or separations using membranes, 4 have the potential to significantly reduce the energy costs. Both technologies depend on the development of novel materials that have optimal properties for a given separation, with important classes of materials being nanoporous solids, such as zeolites and metal−organic frameworks. 3,5−8 By changing the pore topology and chemical composition, one could, in principle, synthesize millions of different materials, making it difficult to experimentally characterize and test all these materials. This gives a great opportunity for molecular simulations to identify the optimal materials in silico and gui...

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Section: ■ Results and Discussionmentioning

confidence: 95%

Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

Kim

Abouelnasr²,

Lin³

et al. 2013

J. Am. Chem. Soc.

114

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“…Extensive research to tailor polyimide chemical structures for better gas separation performance has been carried out in the last two decades [8][9][10][11]. However, structural design attempts to further improve performance have apparently approached a limit as indicated in the trade-off curve describing the relationship between gas permeability and selectivity [12,13]. In addition, no major breakthrough in the improvement of plasticization resistance has been achieved on polyimide membranes through backbone chemical modification or introduction of various side groups in the majority of cases.…”

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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“…Examples include polydimethylsiloxane (PDMS), polyimides, and poly (1-trimethylsilyl-1-propyne) (PTMSP) [1,5,9,10]. The microporous support is made out of mechanically rigid and impermeable materials such as polysulfone, polytetrafluoroethylene (PTFE) and ceramic supports [5].…”

Section: Introductionmentioning

confidence: 99%

Effect of pore penetration on transport through supported membranes studied by electron microscopy and pervaporation

Shin

Jiang

et al. 2017

Journal of Membrane Science

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A B S T R A C TIt has long been recognized that the performance of supported membranes comprising a thin, selective layer and a microporous support layer, is affected by penetration of the selective layer into the porous support. We have attempted to shed light on this phenomenon using a combination of pervaporation experiments and hard angle dark-field scanning transmission electron microscopy (HAADF-STEM). We use a nanophase-separated polystyrene-b-polydimethylsiloxane-b-polystyrene (SDS) as the selective layer and microporous polytetrafluoroethylene (PTFE) as the support layer. Effective permeabilities of butanol and water were measured as a function of selective layer thickness using a dilute butanol/water mixture as the feed in pervaporation. We were able to estimate the pore penetration layer thickness by comparing experiments with model calculations. We were also able to directly observe the pore penetration by HAADF-STEM. The choice in using a nanophaseseparated block copolymer as the selective layer enabled identification of the regions of pore penetration. The pore penetration layer thickness obtained from the HAADF-STEM micrographs corresponded well with estimates based on pervaporation.

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Correlation of separation factor versus permeability for polymeric membranes

Cited by 3,114 publications

References 41 publications

Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

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

Effect of pore penetration on transport through supported membranes studied by electron microscopy and pervaporation

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Correlation of separation factor versus permeability for polymeric membranes

Cited by 3,114 publications

References 41 publications

Large-Scale Screening of Zeolite Structures for CO2 Membrane Separations

Large-Scale Screening of Zeolite Structures for CO2 Membrane Separations

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

Effect of pore penetration on transport through supported membranes studied by electron microscopy and pervaporation

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Product

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Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations

Large-Scale Screening of Zeolite Structures for CO₂ Membrane Separations