The upper bound revisited

Robeson, Lloyd M.

doi:10.1016/j.memsci.2008.04.030

Cited by 5,075 publications

(3,999 citation statements)

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“…Unfortunately, an inherent trade-off exists between permeability and selectivity, that is, highly permeable polymers show low selectivity and vice versa. Robeson developed gas permeability/selectivity upper bound relationships for a variety of gas pairs based on a large database of published permeation data [4].…”

Section: Introductionmentioning

confidence: 99%

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

Alghunaimi

Ghanem

Alaslai

et al. 2015

Journal of Membrane Science

102

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The synthesis and gas permeation properties of two 6FDA-dianhydride-based polyimides prepared from 2,6-diaminotriptycene (6FDA-DAT1) and its extended iptycene analog (6FDA-DAT2) are reported. The additional benzene ring on the extended triptycene moiety in 6FDA-DAT2 increases the free volume over 6FDA-DAT1 and reduces the chain packing efficiency. The BET surface area based on nitrogen adsorption in 6FDA-DAT2 (450 m 2 g -1 ) is ~40% greater than that of 6FDA-DAT1 (320 m 2 g -1 ). 6FDA-DAT1shows a CO 2 permeability of 120 Barrer and CO 2 /CH 4 selectivity of 38, whereas 6FDA-2 DAT2 exhibits a 75% increase in CO 2 permeability to 210 Barrer coupled with a moderate decrease in selectivity (CO 2 /CH 4 = 30). Interestingly, minimal physical aging was observed over 150 days for both polymers and attributed to the high internal free volume of the shape-persistent iptycene geometries. The aged polyimides maintained CO 2 /CH 4 selectivities of 25-35 along with high CO 2 permeabilities of 90-120 Barrer up to partial CO 2 pressures of 10 bar of an aggressive 50:50 CO 2 :CH 4 mixed-gas feed, suggesting potential application in membranes for natural gas sweetening.

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Section: Introductionmentioning

confidence: 99%

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

Alghunaimi

Ghanem

Alaslai

et al. 2015

Journal of Membrane Science

102

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“…[1,2] The performance of a polymeric membrane for gas separation is expressed by its gas permeability and gas pair selectivity, which must be considered together with other important factors such as chemical and mechanical resistance. [5] The determination of permeability and selectivity of membrane materials in conditions as close as possible to the real operating conditions is essential for the design of membrane separation processes of gaseous mixtures and to identify the most appropriate range of conditions, and also to understand the fundamental mechanisms governing the transport processes. To this aim, it is important to point out that the interactions between gases play an important role in membrane gas separation, especially when swelling and/or polar gases are considered, and the transport parameters measured from pure gas experiments often differ significantly from those measured in the mixed gas state.…”

Section: Introductionmentioning

confidence: 99%

“…[5] In particular, the latter polymers lie in the region of ultrahigh permeability (order of magnitude of 1000 Barrer for PIM-1 and 10000 Barrer for PTMSP) and low-medium CO 2 /CH 4 selectivity (around 18 for PIM-1 and around 4 for PTMSP). The solubility selectivity values reported range from 3 to 5 [13] for PIM-1, and from 2 to 3 in PTMSP, according to the pure gas solubility measurements.…”

Section: Introductionmentioning

confidence: 99%

Mixed gas sorption in glassy polymeric membranes: II. CO2/CH4 mixtures in a polymer of intrinsic microporosity (PIM-1)

Vopička

Angelis

et al. 2014

Journal of Membrane Science

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The individual solubility of CH 4 and CO 2 from binary gas mixtures was measured at 35 °C and up to 35 bar in a polymer of intrinsic microporosity (PIM-1), at different compositions of the gas phase (from 0 to 50 mol% of CO 2 ). The experiments were conducted on a pressure-decay apparatus equipped with a gas chromatograph, allowing a highly flexible measuring procedure. The gas solubility was plotted versus gas phase composition, total pressure, gas fugacity and second gas concentration. The mixed gas solubility of both species, CH 4 and CO 2 , is lower than the pure gas value at the same fugacity, but the reduction of methane solubility due to the presence of CO 2 is generally more significant. Such behavior is due to the fact that CO 2 has normally higher solubility than methane: indeed the depression of the solubility coefficient with respect to the pure gas value is similar for both gases, when reported at the same concentration of the second gas.The real, mixed gas solubility selectivity is in general higher than the ideal value calculated from pure gas behavior. The ratio between real and ideal solubility selectivity increases with CO 2 concentration in the membrane, according to a single mastercurve, reaching a maximum value of 4, and increases also with the ratio between CO 2 and CH 4 concentration in the membrane. In particular, as in the case of other glassy polymers, the real solubility selectivity of CO 2 over CH 4 is higher than the ideal value if c(CO 2 )>c(CH 4 ), and it is lower than the ideal value if the opposite condition holds true. Such behavior occurs because the competition for sorption is normally less effective on the more abundant penetrant in the polymer. A selectivity-solubility performance plot can be drawn for this system.

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“…However, trade-off relationships between the permeability and permselectivity have been often observed [18]. In addition, polymers which may have high permeability and pemselectivity tend to have low membrane forming ability.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of soluble oligsiloxane-end-capped hyperbranched polyazomethine and their application to CO₂/N₂ separation membranes

Lei

Jing

et al. 2018

Designed Monomers and Polymers

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Three soluble hyperbranched polyazomethines containing oligosiloxane end group HBP-PAZ-SiOn were successfully synthesized. HBP-PAZ-SiOns were used as modifiers of ethyl cellulose (EC) and polysulfone (PS) membranes. Blend membranes, HBP-PAZ-SiOn/EC and HBP-PAZ-SiOn/PS were prepared by blending the THF solution of HBP-PAZ-SiOn with ethanol solution of EC and dichloromethane solution of PS, respectively. Surprisingly, the permeabilities for CO2 of the blend membranes were more than 15–16 times higher than those of pure EC and PS membranes without any drop of pemselectivity to N2. This unusual improvement has been achieved by both enhancement of diffusivity for carbon dioxide and nitrogen by the oligosiloxane groups and enhancement of affinity of the amino groups with carbon dioxide at the end groups of HBP-PAZ-SiOn.

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The upper bound revisited

Cited by 5,075 publications

References 69 publications

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

Mixed gas sorption in glassy polymeric membranes: II. CO2/CH4 mixtures in a polymer of intrinsic microporosity (PIM-1)

Synthesis of soluble oligsiloxane-end-capped hyperbranched polyazomethine and their application to CO₂/N₂ separation membranes

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The upper bound revisited

Cited by 5,075 publications

References 69 publications

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

Mixed gas sorption in glassy polymeric membranes: II. CO2/CH4 mixtures in a polymer of intrinsic microporosity (PIM-1)

Synthesis of soluble oligsiloxane-end-capped hyperbranched polyazomethine and their application to CO2/N2 separation membranes

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Synthesis of soluble oligsiloxane-end-capped hyperbranched polyazomethine and their application to CO₂/N₂ separation membranes