Gas separation membrane

A method of fabricating a gas separation membrane includes providing a coextruded multilayer film that includes a first polymer layer formed of a first polymer material and a second polymer layer formed of a second polymer material, the first polymer material having a first gas permeability. The coextruded multilayer film is axially oriented such that the second polymer layer has a second gas permeability that is greater than the first gas permeability.Board of Regents, University of Texas Syste

Novel Nanocomposite Membrane Structures for H2 Separations

This report explores possible methods of improving CO{sub 2} selectivity in polymer based membranes. The first method investigated using basic nanoparticles to enhance the solubility of acid gases in nanocomposite membranes, thus enhancing the overall acid gas/light gas selectivity (e.g., CO{sub 2}/H{sub 2}, CO{sub 2}/CH{sub 4}, etc.). The influence of nanoparticle surface chemistry on nanocomposite morphology and transport properties will be determined experimentally in a series of poly(1-trimethylsilyl-1-propyne). Additional factors (e.g., chemical reaction of the particles with the polymers) have been considered, as necessary, during the course of the investigation. The second method investigated using polar polymers such as crosslinked poly(ethylene oxide) and poly(ether-b-amide) to improve CO{sub 2} sorption and thereby increase CO{sub 2} permeability and CO{sub 2}/light gas selectivity. For both types of materials, CO{sub 2} and light gas permeabilities have been characterized. The overall objective was to improve the understanding of materials design strategies to improve acid gas transport properties of membranes

Polybenzimidazoles and methods of making and using thereof

Disclosed are polybenzimidazoles containing sulfonyl groups. The polymers can be synthesized in Eaton's reagent from 3,3′,4,4′-tetraaminodiphenylsulfone, which itself can be synthesized from 4,4′-dichlorodiphenylsulfone. Methods of synthesizing the polymers are disclosed. The disclosed polymers can be used for high temperature H2/CO2 separation membranes and other uses.Board of Regents, University of Texas Syste

Process of forming crosslinked copolymer film, crosslinked copolymer film formed thereby, and water purification membrane

Azidoaryl-substituted cyclooctene monomers and synthesized and used in the preparation of various copolymers. Among these copolymers are those prepared from ring-opening metathesis polymerization of cyclooctene, polyethylene glycol-substituted cyclooctene, and azidoaryl-substituted cyclooctene. These copolymers are useful in the formation of crosslinked films that reduce fouling of water purification membranes.Board of Regents, University of Texas Syste

Energy-efficient polymeric gas separation membranes for a sustainable future: A review

AbstractOver the past three decades, polymeric gas separation membranes have become widely used for a variety of industrial gas separations applications. This review presents the fundamental scientific principles underpinning the operation of polymers for gas separations, including the solution-diffusion model and various structure/property relations, describes membrane fabrication technology, describes polymers believed to be used commercially for gas separations, and discusses some challenges associated with membrane materials development. A description of new classes of polymers being considered for gas separations, largely to overcome existing challenges or access applications that are not yet practiced commercially, is also provided. Some classes of polymers discussed in this review that have been the focus of much recent work include thermally rearranged (TR) polymers, polymers of intrinsic microporosity (PIMs), room-temperature ionic liquids (RTILs), perfluoropolymers, and high-performance polyimides

On a discrete Davey-Stewartson system

We propose a differential difference equation in ${\mathcal R}^1\times {\mathcal Z}^2$ and study it by Hirota's bilinear method. This equation has a singular continuum limit into a system which admits the reduction to the Davey-Stewartson equation. The solutions of this discrete DS system are characterized by Casorati and Grammian determinants. Based on the bilinear form of this discrete DS system, we construct the bilinear B\"{a}cklund transformation which enables us to obtain its Lax pair.Comment: 12 pages, 2 figure

Nonequilibrium Lattice Fluid Modeling of Gas Solubility in HAB-6FDA Polyimide and Its Thermally Rearranged Analogues

For the first time, a theoretical analysis of gas sorption, based on the nonequilibrium lattice fluid (NELF) model, in chemically imidized HAB-6FDA polyimide and its thermally rearranged analogues is presented. Because of the inaccessibility of pVT data in the rubbery region, the characteristic lattice fluid parameters of the polymers considered in this study were obtained from a collection of infinite dilution solubility data at multiple temperatures. Hydrogen, nitrogen, and methane sorption isotherms at 35 °C were fit to the NELF model using one adjustable parameter, i.e., the polymer–penetrant binary interaction parameter, k₁₂. The optimal value of k₁₂ for each polymer–penetrant pair was used to predict hydrogen, nitrogen, and methane sorption isotherms at other temperatures and at pressures up to 6 MPa. For carbon dioxide, a second adjustable parameter, the swelling coefficient, was introduced to account for sorption-induced matrix dilation. The ideal solubility–selectivity is also predicted for several gas pairs. The increase in gas sorption in thermally rearranged samples relative to their polyimide precursor is essentially due to entropic effects, i.e., to the increase in nonequilibrium fractional free volume during thermal rearrangement.United States. Department of Energy (Grant DE-FG02-02ER15362

Effect of polymer structure on gas transport properties of selected aromatic polyimides, polyamides and TR polymers

Thermally rearranged (TR) polymers are formed through a thermally induced solid-state reaction of polyimides or polyamides that contain nucleophilic reactive groups ortho-positioned to their diamine. Naturally, the transport properties of TR polymers are intimately related to the chemical structure and reactivity of their precursors. Herein, we report characterization and transport properties for three poly(hydroxyimide) precursors prepared via thermal imidization in solution and for their corresponding TR polymers. Structural modifications to the polymer backbone can be used to control thermal rearrangement reaction kinetics. In regards to TR polymer formation, samples prepared from diamines with biphenyl functionality reacted more efficiently than those prepared from diamines with hexafluoroisopropylidene-linked aromatic units. However, hexafluoroisopropylidene functional units provided the highest combinations of permeability and selectivity for separations involving H2, N2, O2, CH4, and CO2. Differences in permeability between samples correlated well with changes in free volume, and 3 poly(hydroxyimide)s showed unusually high selectivities for their given free volume. The effect of synthesis route was also investigated for a specific TR polymer derived from 3,3'-dihydroxy-4,4'-diamino-biphenyl (HAB) and 2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). Poly(hydroxyimide) precursors prepared via thermal imidization in solution and thermal imidization in the solid-state showed nearly identical permeabilities and selectivities regardless of synthesis route. However, after thermal rearrangement, the TR polymers prepared from polyimides synthesized via solid-state imidization have higher gas permeabilities than their solution-imidized analogs. In addition to light gas permeabilities, plasticization effects were investigated with CO2 hysteresis loops for all samples, and pure-gas olefin/paraffin permeabilities were determined for a TR polymer derived from 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (APAF) and 6FDA. With the exception of HAB-6FDA polyimides, pure-gas CO2 feed pressures up to approximately 50bar do not reveal a plasticization pressure point, but conditioning effects are observed for most samples. APAF-6FDA TR polymers have pure-gas permeabilities and selectivities beyond the propylene/propane upper bound.The authors gratefully acknowledge the support from Grant DE-FG02-02ER15362,whichwasadministeredbytheU.S.De-partment of Energy(DOE), Division of Chemical Sciences, Geos-ciences, and Biosciences through the Office of Basic Energy Sciences. Additionally, the authors gratefully acknowledge support from the DOEO ffice of Science Graduate Fellowship Program, which managed under DOE contract number DE-AC05-06OR23100 by Oak Ridge Associated Universities (ORAU) and adinistered by the Oak Ridge Institute for Science and Education (ORISE).Peer Reviewe

Free volume and permeability of mixed matrix membranes made from a Terbutil-M-terphenyl polyamide and a porous polymer network

Producción CientíficaA set of thermally rearranged mixed matrix membranes (TR-MMMs) was manufactured and tested for gas separation. These membranes were obtained through the thermal treatment of a precursor MMM with a microporous polymer network and an o-hydroxypolyamide,(HPA) created through a reaction of 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (APAF) and 5′-terbutil-m-terfenilo-3,3″-dicarboxylic acid dichloride (tBTmCl). This HPA was blended with different percentages of a porous polymer network (PPN) filler, which produced gas separation MMMs with enhanced gas permeability but with decreased selectivity. The thermal treatment of these MMMs gave membranes with excellent gas separation properties that did not show the selectivity decreasing trend. It was observed that the use of the PPN load brought about a small decrease in the initial mass losses, which were lower for increasing PPN loads. Regarding the glass transition temperature, it was observed that the use of the filler translated to a slightly lower Tg value. When these MMMs and TR-MMMs were compared with the analogous materials created from the isomeric 5′-terbutil-m-terfenilo-4,4″-dicarboxylic acid dichloride (tBTpCl), the permeability was lower for that of tBTmCl, compared with the one from tBTpCl, although selectivity was quite similar. This fact could be attributed to a lower rigidity as roughly confirmed by the segmental length of the polymer chain as studied by WAXS. A model for FFV calculation was proposed and its predictions compared with those evaluated from density measurements assuming a matrix-filler interaction or ideal independence. It turns out that permeability as a function of FFV for TR-MMMs follows an interaction trend, while those not thermally treated follow the non-interaction trend until relatively high PPN loads were reached.Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación - (projects PID2019- 109403RB-C21/AEI/10.13039/501100011033 and PID2019-109403RB-C22/AEI/10.13039/501100011033)Junta de Castilla y León, Unión Europea y Fondo Europeo de Desarrollo Regional (FEDER) - (project CLU2017-09, UIC082