scholarly journals Pentiptycene-based ladder polymers with configurational free volume for enhanced gas separation performance and physical aging resistance

2021 ◽  
Vol 118 (37) ◽  
pp. e2022204118
Author(s):  
Tanner J. Corrado ◽  
Zihan Huang ◽  
Dezhao Huang ◽  
Noah Wamble ◽  
Tengfei Luo ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeation ◽  
Separation Performance ◽  
Structure Property ◽  
Mixed Gas ◽  
Initial Separation ◽  
Primary Advantage ◽  
Polymers Of Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) have shown promise in pushing the limits of gas separation membranes, recently redefining upper bounds for a variety of gas pair separations. However, many of these membranes still suffer from reductions in permeability over time, removing the primary advantage of this class of polymer. In this work, a series of pentiptycene-based PIMs incorporated into copolymers with PIM-1 are examined to identify fundamental structure–property relationships between the configuration of the pentiptycene backbone and its accompanying linear or branched substituent group. The incorporation of pentiptycene provides a route to instill a more permanent, configuration-based free volume, resistant to physical aging via traditional collapse of conformation-based free volume. PPIM-ip-C and PPIM-np-S, copolymers with C- and S-shape backbones and branched isopropoxy and linear n-propoxy substituent groups, respectively, each exhibited initial separation performance enhancements relative to PIM-1. Additionally, aging-enhanced gas permeabilities were observed, a stark departure from the typical permeability losses pure PIM-1 experiences with aging. Mixed-gas separation data showed enhanced CO2/CH4 selectivity relative to the pure-gas permeation results, with only ∼20% decreases in selectivity when moving from a CO2 partial pressure of ∼2.4 to ∼7.1 atm (atmospheric pressure) when utilizing a mixed-gas CO2/CH4 feed stream. These results highlight the potential of pentiptycene’s intrinsic, configurational free volume for simultaneously delivering size-sieving above the 2008 upper bound, along with exceptional resistance to physical aging that often plagues high free volume PIMs.

scholarly journals Integration of Stable Ionic Liquid-Based Nanofluids into Polymer Membranes. Part II: Gas Separation Properties toward Fluorinated Greenhouse Gases

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 582
Author(s):  
Fernando Pardo ◽  
Sergio V. Gutiérrez-Hernández ◽  
Carolina Hermida-Merino ◽  
João M. M. Araújo ◽  
Manuel M. Piñeiro ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Gas Separation ◽  
Value Added ◽  
Gas Permeation ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Mixed Gas ◽  
Neat Polymer ◽  
Stable Suspension ◽  
Base Polymer

Membrane technology can play a very influential role in the separation of the constituents of HFC refrigerant gas mixtures, which usually exhibit azeotropic or near-azeotropic behavior, with the goal of promoting the reuse of value-added compounds in the manufacture of new low-global warming potential (GWP) refrigerant mixtures that abide by the current F-gases regulations. In this context, the selective recovery of difluorometane (R32, GWP = 677) from the commercial blend R410A (GWP = 1924), an equimass mixture of R32 and pentafluoroethane (R125, GWP = 3170), is sought. To that end, this work explores for the first time the separation performance of novel mixed-matrix membranes (MMMs) functionalized with ioNanofluids (IoNFs) consisting in a stable suspension of exfoliated graphene nanoplatelets (xGnP) into a fluorinated ionic liquid (FIL), 1-ethyl-3-methylpyridinium perfluorobutanesulfonate ([C2C1py][C4F9SO3]). The results show that the presence of IoNF in the MMMs significantly enhances gas permeation, yet at the expense of slightly decreasing the selectivity of the base polymer. The best results were obtained with the MMM containing 40 wt% IoNF, which led to an improved permeability of the gas of interest (PR32 = 496 barrer) with respect to that of the neat polymer (PR32 = 279 barrer) with a mixed-gas separation factor of 3.0 at the highest feed R410A pressure tested. Overall, the newly fabricated IoNF-MMMs allowed the separation of the near-azeotropic R410A mixture to recover the low-GWP R32 gas, which is of great interest for the circular economy of the refrigeration sector.

scholarly journals Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity—Effect of Distribution and the Gas Separation Performance

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1241 ◽  
Author(s):  
Silvio Neumann ◽  
Gisela Bengtson ◽  
David Meis ◽  
Volkan Filiz
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Time Lag ◽  
Polymer Chains ◽  
Separation Performance ◽  
Polymer Backbone ◽  
Cross Linkage ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs.

scholarly journals Polymer of Intrinsic Microporosity (PIM-1) Membranes Treated with Supercritical CO2

Membranes ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 41 ◽  
Author(s):  
Colin Scholes ◽  
Shinji Kanehashi
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Supercritical Co2 ◽  
Physical Aging ◽  
Size Exclusion ◽  
Membrane Morphology ◽  
Polymers Of Intrinsic Microporosity ◽  
Micro Cavity ◽  
The Impact ◽  
Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) are a promising membrane material for gas separation, because of their high free volume and micro-cavity size distribution. This is countered by PIMs-based membranes being highly susceptible to physical aging, which dramatically reduces their permselectivity over extended periods of time. Supercritical carbon dioxide is known to plasticize and partially solubilise polymers, altering the underlying membrane morphology, and hence impacting the gas separation properties. This investigation reports on the change in PIM-1 membranes after being exposed to supercritical CO2 for two- and eight-hour intervals, followed by two depressurization protocols, a rapid depressurization and a slow depressurization. The exposure times enables the impact contact time with supercritical CO2 has on the membrane morphology to be investigated, as well as the subsequent depressurization event. The density of the post supercritical CO2 exposed membranes, irrespective of exposure time and depressurization, were greater than the untreated membrane. This indicated that supercritical CO2 had solubilised the polymer chain, enabling PIM-1 to rearrange and contract the free volume micro-cavities present. As a consequence, the permeabilities of He, CH4, O2 and CO2 were all reduced for the supercritical CO2-treated membranes compared to the original membrane, while N2 permeability remained unchanged. Importantly, the physical aging properties of the supercritical CO2-treated membranes altered, with only minor reductions in N2, CH4 and O2 permeabilities observed over extended periods of time. In contrast, He and CO2 permeabilities experienced similar physical aging in the supercritical treated membranes to that of the original membrane. This was interpreted as the supercritical CO2 treatment enabling micro-cavity contraction to favour the smaller CO2 molecule, due to size exclusion of the larger N2, CH4 and O2 molecules. Therefore, physical aging of the treated membranes only had minor impact on N2, CH4 and O2 permeability; while the smaller He and CO2 gases experience greater permeability loss. This result implies that supercritical CO2 exposure has potential to limit physical aging performance loss in PIM-1 based membranes for O2/N2 separation.

scholarly journals Boosting gas separation performance and suppressing the physical aging of polymers of intrinsic microporosity (PIM-1) by nanomaterial blending

Nanoscale ◽  
2020 ◽  
Vol 12 (46) ◽  
pp. 23333-23370 ◽  
Author(s):  
Mohd Zamidi Ahmad ◽  
Roberto Castro-Muñoz ◽  
Peter M. Budd
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Ideal Gas ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Hybrid Fillers ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity ◽  
Gas Separation Performance ◽  
The Ideal

The development of PIM-1 mixed matrix membranes using organic, inorganic and hybrid fillers towards the ideal gas separation enhancement.

scholarly journals Hollow Fiber Polyimide Membranes Prepared in a Triple Orifice Spinneret: Effect of a Reduced Water Activity in the Bore Fluid on the Gas Separation Performance

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2211
Author(s):  
Paola Bernardo ◽  
Franco Tasselli ◽  
Gabriele Clarizia
Keyword(s):  
Gas Separation ◽  
Water Activity ◽  
Physical Aging ◽  
Saline Water ◽  
Water Solution ◽  
Gas Permeation ◽  
Hollow Fibers ◽  
Separation Performance ◽  
Fluid Composition ◽  
Gas Selectivity

Polyimide-based hollow fibers were spun using a triple orifice spinneret in order to apply them in gas separation. The membrane structure was tailored producing a porous external layer and a thin internal skin layer, that controlled the gas transport. The measurement of gas permeation rates and the morphological analysis were combined to obtain information on the performance of the membranes. The aim was to tune the inner top layer and investigate the role of the bore fluid on the gas permeation properties of the membranes. The bore fluid composition was explored by using water mixtures containing the solvent used for preparing the dope solution or a salt in order to reduce the water activity in the inner coagulant, but also a low amount of a crosslinker for improving the gas selectivity. The change of the dope flow-rate was also analyzed. At moderate dope flow-rates, the use of a saline water solution as bore fluid is more effective in enhancing the membrane gas selectivity with respect to a bore fluid containing certain amounts of solvent. This option represents a green approach for the preparation of the membrane. The behavior of the prepared hollow fibers over time (physical aging) in gas permeation was discussed.

scholarly journals The spirobichroman-based polyimides with different side groups: from structure–property relationships to chain packing and gas transport performance

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5086-5095
Author(s):  
Shuli Wang ◽  
Xiaohua Tong ◽  
Chunbo Wang ◽  
Xiaocui Han ◽  
Sizhuo Jin ◽  
...  
Keyword(s):  
Dihedral Angle ◽  
Gas Separation ◽  
Gas Transport ◽  
Critical Role ◽  
Polymer Membranes ◽  
Separation Performance ◽  
Structure Property ◽  
Chain Packing ◽  
Structure Property Relationships ◽  
Gas Separation Performance

Effect of substituents on the dihedral angle and chain packing plays a critical role in the enhancement in the gas separation performance of polymer membranes.

scholarly journals Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

Membranes ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 214-227 ◽  
Author(s):  
Muntazim Khan ◽  
Volkan Filiz ◽  
Thomas Emmler ◽  
Volker Abetz ◽  
Toenjes Koschine ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Permeation ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

scholarly journals The CO2/CH4 Separation Potential of ZIF-8/Polysulfone Mixed Matrix Membranes at Elevated Particle Loading for Biogas Upgradation Process

2020 ◽  
Vol 10 (2) ◽  
pp. 213-219
Author(s):  
Putu Doddy Sutrisna ◽  
Ronaldo Pangestu Hadi ◽  
Jonathan Siswanto ◽  
Giovanni J Prabowo
Keyword(s):  
Renewable Energy ◽  
Gas Separation ◽  
Gas Permeability ◽  
Gas Permeation ◽  
Degree Of Crystallinity ◽  
Polymeric Membrane ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Particle Loading ◽  
Inorganic Particles

Biogas is a renewable energy that has been explored widely in Indonesia to substitute non-renewable energy. However, the presence of certain gas, such as carbon dioxide (CO2), can decrease the calorific value and generate greenhouse gas. Hence, the separation of CO2 from methane (CH4) occurs as a crucial step to improve the utilization of biogas. The separation of CH4/CO2 can be conducted using a polymeric membrane that needs no chemical, hence considered as an environmentally friendly technique. However, the utilization of polymeric membrane in gas separation processes is hampered by the trade-off between gas throughput and selectivity. To solve this problem, the incorporation of inorganic particles, such as Zeolitic Imidazolate Framework-8 (ZIF-8) particles, into the polymer matrix to improve the gas separation performance of the membrane has been conducted recently. In this research, ZIF-8 has been incorporated into Polysulfone matrix to form ZIF-8/Polysulfone-based membrane by simple blending and phase inversion techniques in flat sheet configuration. The pure gas permeation tests showed an increase in gas permeability (26 Barrer compared to 17 Barrer) after the inclusion of ZIF-8 particles with a slight decrease in CO2/CH4selectivity for particle loading more than 15wt. %. Therefore, the membrane with 15wt. % of particles showed the best performance in terms of gas selectivity. This result was due to the aggregation of ZIF-8 particles at particle loading higher than 15wt. %. Chemical analysis indicated an interaction between filler and polymer, and there were increases in the degree of crystallinity after the incorporation of ZIF-8.

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