Separation article for selectively removing difluoromethane from a gas mixture and method of use thereof - Patents.com

Abstract

The present disclosure relates to separation articles, such as films, membranes, etc., that separate at least one component from a gas mixture containing two or more components, including difluoromethane (HFC-32, CH2F2) and pentafluoroethane (HFE-125, C2F5H). The articles of the present disclosure include a "selective layer" that is selectively permeable to the desired component to be separated from the gas mixture. The selective layer is composed of an amorphous fluorinated copolymer. Optionally, the article may have other layers that serve various purposes, such as a porous support layer, a "gutter layer" through which permeating gas may pass from the selective layer to the porous layer with the least resistance, and a protective layer that protects the selective layer from contamination. Each component of the separation articles disclosed herein and the methods of making and using them are described below.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Application No. 63 / 295,108, filed December 30, 2021, which is incorporated by reference herein in its entirety.

[0002] [Background technology] Hydrofluorocarbons (HFCs) are a class of chemical compounds commonly used in refrigeration and air conditioning systems. These refrigerants were created to replace chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants, which are linked to the depletion of the Earth's ozone layer. The Kyoto Protocol, an international treaty extending the 1992 United Nations Framework Convention on Climate Change, mandated the use of HFCs. 1 In addition, EU Regulation No. 517 / 2014 has put into force a target of reducing fluorinated greenhouse gas emissions by up to two-thirds by 2030 compared to 2010. 2 More recently, the 2020 U.S. emergency economic package passed as a result of the COVID-19 pandemic included provisions to reduce the production and import of HFC refrigerants by 85% by 2035, and to implement the Kigali Amendment, an international platform for preventing up to 0.5°C of global warming. 3 In international and national efforts to limit the use of high GWP (Global Warming Potential) HFCs, energy-efficient separation methods are needed to effectively dispose of and recycle azeotropic refrigerant mixtures that will be phased out over the next 20 years.

[0003] HFC-32(CH 2 F 2 ) 50% by mass and HFC-125 (CHF 2 CF3 R-410A, a near-azeotropic refrigerant mixture consisting of 50% by mass of HCFC-22, was developed as a replacement for HCFC-22 and is widely used in commercial and residential air conditioning applications. 4 R-410A is a fluorocarbon fluoride (HCFC-22, CHClF), the use of which was banned in new equipment in 2010. 2 With significant amounts of HFCs in circulation worldwide (estimated at 1000 kilotons of HFC worldwide), the question of how industry will dispose of the surplus of unused R-410A and HFC refrigerants is a timely issue that is complicated by the lack of an industrially feasible method for separating the azeotropes. 5 When R-410A cannot be separated into its constituent refrigerants, excess stocks of the refrigerant will likely end up being incinerated or released into the atmosphere. Although releasing unused refrigerants is illegal, it is done without strict oversight. High temperature incineration is the only disposal method that exists, but it is not only expensive but also energy intensive. Thus, the need for a sustainable method to separate HFC-32 from R-410A is a timely issue that becomes critical due to existing and upcoming regulations of refrigerant blends.

[0004] Fluorinated refrigerant gases are usually separated by distillation, which relies on the difference in boiling points and vapor pressures of the components as the primary separation mechanism. In some cases, however, there are important separation problems when the components are azeotropic or near azeotropic, making distillation-based separation methods impractical. For example, the widely used refrigerant R-410A consists of an azeotropic mixture of two compounds, HFC-32, which has a relatively low global warming potential, and HFC-125, which has a relatively high global warming potential. In such cases, it is preferable to separate the lower GWP value component for reuse and the higher GWP value component for incineration or other forms of disposal.

[0005] Membrane-based gas separation methods operate on the principle of differential permeability of gases through a selective layer of a membrane, which is often made of a polymer. The membrane material in such separation processes is chosen to provide very high permeability to one or more gases and very low permeability to other gases. A mixed gas stream is then introduced to one side of the membrane, with the more permeable gases preferentially passing through the membrane, creating a "permeate" gas stream on the other side of the membrane. This permeate stream is enriched in the high permeability gases compared to the input gas stream. Meanwhile, the input stream travels from the input surface of the membrane towards the outlet of the membrane module and is enriched in the low permeability species compared to the input gas stream. This stream is called the "retentate" stream [see, for example, Baker, Membrane Technology and Applications, Wiley, West Sussex, 2012].

[0006] Because membrane-based separation requires only a pressure difference across the membrane to operate, it can be achieved with relatively simple and reliable equipment, which usually consists mainly of a compressor and a membrane module. For the same reason, it usually requires much less energy than the gas separation methods mentioned above. Furthermore, membrane-based separation methods for gas separation avoid the use of toxic and corrosive substances such as alkylamines, which are often used in chemical adsorption methods, and usually have significantly lower capital costs.

[0007] Furthermore, because membrane-based separation methods separate components based on differences in the permeability of the components through a polymer membrane, their separation characteristics are usually significantly different from those of distillation processes. Thus, azeotropes in which the component gases have substantially different membrane permeabilities can be separated by membrane methods even when they cannot be separated by distillation methods. Thus, membrane-based separation methods are potentially promising separation methods for certain azeotropes and near-azeotropes of refrigerants or other gases.

[0008] [overview] In this specification, gases, in particular difluoromethane (HFC-32, CH 2 CF 2) and pentafluoroethane (HFC-125, C 2 F 5 H) mixtures. The articles have a selective layer comprising an amorphous fluorinated copolymer. In one aspect, the selective layer exhibits low permeability to pentafluoroethane but relatively high permeability to difluoromethane, resulting in a highly selective membrane. Methods of making and using the articles described herein are also provided.

[0009] Other methods, features, and advantages of the present disclosure will be or become apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. All additional systems, methods, features, and advantages are included herein, are within the scope of the present disclosure, and are protected by the accompanying claims. Furthermore, all optional and preferred features and modifications of the described embodiments can be used in all aspects of the disclosure described herein. Furthermore, the individual features of the dependent claims, and all optional and preferred features and modifications of the described embodiments can be combined with each other and substituted for each other. [Brief description of the drawings]

[0010] Many aspects of the present disclosure can be better understood with reference to the following drawings. The elements in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numbers indicate corresponding parts in the several drawings. [Figure 1] FIG. 1 shows the 19F NMR of an exemplary PDD-co-PBVE copolymer used herein. [Diagram 2] FIG. 2 shows a static membrane apparatus for measuring the permeability of HFC-32 and HFC-125 through the amorphous fluorinated copolymers disclosed herein. [Diagram 3] FIG. 3 shows the permeability of PBVE-co-PDD polymer to HFC-32 (open circles) and HFC-125 (squares) at 35° C. and 2 bar. [Figure 4]FIG. 4 shows the ideal selectivity of the PBVE-co-PDD polymer at 35° C. and 2 bar. [Diagram 5] FIG. 5 shows the mixed gas permeability apparatus used to measure the mixed gas selectivity of HFC-32 and HFC-125. [Figure 6] FIG. 6 shows the solubility of HFC-32 (open circles) and HFC-125 (squares) in PBVE-co-PDD polymer at 35° C. and 2 bar.

[0011] [Detailed Description] Numerous modifications and other embodiments of the disclosed compositions and methods may occur to one skilled in the art having the benefit of the teachings in the foregoing descriptions and the associated drawings. It is therefore to be understood that the disclosure is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. Those skilled in the art may recognize numerous variations and applications of the aspects described herein. These variations and applications are intended to be included within the teachings of the disclosure and encompassed by the claims.

[0012] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0013] As will be apparent to one of ordinary skill in the art upon reading this specification, each embodiment described and illustrated herein has individual elements and features that may be readily extracted or combined with features of any of the other several embodiments without departing from the scope or concept of the disclosure.

[0014] Any recited method may be carried out in the order of events recited or in any other order that is logically possible. That is, unless expressly stated, it is not intended that any method or aspect described herein be construed as requiring that its steps be performed in a particular order. Thus, any method claim is not intended to imply any order in any respect unless the claim or specification specifically states that the steps are limited to a particular order. This is true whether for logical considerations regarding the arrangement of steps or operational flow, a clear meaning derived from grammatical structure or punctuation, or for any non-express basis for interpretation, including the number or type of aspects described in the specification, etc.

[0015] All publications mentioned herein are incorporated by reference to disclose and describe the methods and / or materials for which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of this application. Nothing herein should be construed as an admission that the present invention is not entitled to antedate such publications by virtue of prior invention. Further, the publication dates of publications provided herein may be different from the actual publication dates and may require individual confirmation.

[0016] Although aspects of the disclosure may be described and claimed in a particular system statutory class, such as a system class, this is for convenience only and those skilled in the art will understand that aspects of the disclosure may be described and claimed in any statutory class.

[0017] It is also understood that the terms used herein are only for describing certain aspects and are not intended to be limiting. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the disclosed compositions and methods belong. In addition, it is also understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the present specification and related art, and should not be interpreted in an ideal or moderately formal sense unless expressly specified in the present specification.

[0018] Prior to describing the various aspects of this disclosure, the following definitions are provided and shall be used unless otherwise indicated. Other terms may be defined elsewhere in this disclosure.

[0019] [Definition] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or variations thereof are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises listed elements is not limited to only those elements and may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Additionally, the term "comprising" is intended to include examples and embodiments that are included within the terms "consisting essentially of" and "consisting of." Similarly, the term "consisting essentially of" is intended to include examples that are included within the term "consisting of."

[0020] The terms "about," "approximate," "at or about," and "substantially" as used herein mean that the amount or value in question may be or is exactly that value that will produce the same results or effects as disclosed in the claims or taught herein. That is, the amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as necessary, to produce the same results or effects, reflecting tolerances, conversion factors, rounding, measurement errors, and the like, and other factors known to those skilled in the art. In some circumstances, values ​​that will produce the same results or effects may not be reasonably determinable. In such cases, "about" and "approximately" as used herein are generally understood to mean a variation of ±10% of the nominal value indicated, unless otherwise stated or implied. In general, amounts, sizes, formulations, parameters, or other quantities or characteristics are "about," "approximately," or "nearly," whether or not expressly stated. When "about," "approximately," or "nearly" is used before a quantitative value, it is understood that the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0021] As used herein, the terms "optional" and "optionally" mean that the subsequently described event or circumstance may or may not occur, and are meant to include both cases where such event or circumstance occurs and cases where it does not occur.

[0022] As used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "fluorinated cyclic monomer," a "comonomer," or a "copolymer" includes, but is not limited to, mixtures or combinations of two or more such fluorinated cyclic monomers, comonomers, or copolymers.

[0023] As used herein, the term "gas" means gas or vapor.

[0024] The term "polymer" as used herein generally includes, but is not limited to, homopolymers, copolymers (e.g., block, graft, random and alternating copolymers, terpolymers, etc.), as well as mixtures and modifications thereof. Furthermore, unless otherwise limited, the term "polymer" can include all possible geometric structures. These structures include, but are not limited to, isotactic and atactic symmetries.

[0025] The term "ideal selectivity" refers to the ratio of the permeability of HFC-32 divided by the permeability of HFC-125 (α HFC-32 / HFC-125 An exemplary method for measuring the permeability of HFC-32 and HFC-125 is provided in Example 2 herein.

[0026] The term "diffusivity ratio" refers to the ratio of the solubility of HFC-32 divided by the solubility of HFC-125 (D HFC-32 / D HFC-32 An exemplary method for measuring the solubility of HFC-32 and HFC-125 is provided in Example 8 herein.

[0027] As used herein, the term "highly fluorinated" means that at least 50% of the available hydrogens attached to a carbon are replaced with fluorine atoms.

[0028] As used herein, the terms "fully fluorinated" and "perfluorinated" are used interchangeably and refer to compounds in which all of the available hydrogens bonded to carbons have been replaced with fluorine atoms.

[0029] The term "alkyl" as used herein refers to a branched or unbranched saturated hydrocarbon group having 1 to 24 carbon atoms, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, etc. The alkyl group can be cyclic or acyclic. The alkyl group can be branched or unbranched. The alkyl group can be substituted or unsubstituted. For example, the alkyl group can be substituted with one or more groups, including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halogen, hydroxy, nitro, silyl, sulfoxo, or thiol, as described herein. A "lower alkyl" group is an alkyl group containing 1 to 6 (e.g., 1 to 4) carbon atoms. The term alkyl group can be C1 alkyl, C1-C2 alkyl, C1-C3 alkyl, C1-C4 alkyl, C1-C5 alkyl, C1-C6 alkyl, C1-C7 alkyl, C1-C8 alkyl, C1-C9 alkyl, C1-C10 alkyl, etc., including up to C1-C24 alkyl.

[0030] Throughout the specification, "alkyl" is generally used to refer to both unsubstituted and substituted alkyl groups, but substituted alkyl groups are referred to herein by specifying specific substituents on the alkyl group. For example, the term "halogenated alkyl" or "haloalkyl" specifically refers to an alkyl group substituted with one or more halogen atoms, such as fluorine, chlorine, bromine, or iodine. Alternatively, the term "monohaloalkyl" specifically refers to an alkyl group substituted with one halogen atom, such as fluorine, chlorine, bromine, or iodine. The term "polyhaloalkyl" specifically refers to an alkyl group independently substituted with two or more halogen atoms, i.e., each halogen substituent need not be the same halogen substituent as the other halogen substituents, and multiple instances of a halogen substituent need not be on the same carbon. The term "alkoxyalkyl" specifically refers to an alkyl group substituted with one or more alkoxy groups, as specifically described below. The term "aminoalkyl" specifically refers to an alkyl group substituted with one or more amino groups. The term "hydroxyalkyl" specifically refers to an alkyl group substituted with one or more hydroxy groups. Where "alkyl" is used in one instance and a specific term such as "hydroxyalkyl" is used in another instance, this is not meant to mean that the term "alkyl" does not also refer to the specific term such as "hydroxyalkyl."

[0031] The term "alkenyl" or "olefin" as used herein refers to a fluorocarbon group of 2 to 24 carbon atoms having a structural formula containing at least one carbon-carbon double bond. 1 A 2 )C=C(A 3 A 4 ), are intended to include both the E and Z isomers. This may be inferred in structural formulas herein where an asymmetric alkene group or olefin is present or may be explicitly indicated by the bond symbol C=C. In one embodiment, an "alkenyl" or "olefin" compound may contain two carbon-carbon double bonds (e.g., is a diene).

[0032] It should be noted that percentages, concentrations, amounts, and other numerical data may be expressed herein in a range format. It will further be understood that the endpoints of each range are significant in relation to the other endpoint, and independently of the other endpoint. A number of numerical values ​​are disclosed herein, and it will be understood that each numerical value is herein disclosed as "about" that particular value in addition to the value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. Ranges may be expressed herein as "about" one particular value and / or to "about" another particular value. Similarly, when values ​​are expressed as approximations, using the antecedent "about," the particular value may form a further aspect. For example, when the value "about 10" is disclosed, then "10" is also disclosed.

[0033] When a range is expressed, in a further embodiment, it includes from one particular value and / or to another particular value. For example, if the stated range includes one or both of the limits, ranges not including either or both of the included limits are also included in the disclosure. For example, the phrase "from x to y" includes ranges from "x" to "y" as well as ranges from greater than "x" to less than "y". When a range may be stated as an upper limit, such as the phrase "about x, y, z, or less", it may be interpreted to include the specific ranges "about x", "about y", and "about z", as well as the ranges "less than x", "less than y", and "less than z". Similarly, the phrase "about x, y, z, or greater" may be interpreted to include the specific ranges "about x", "about y", and "about z", as well as the ranges "greater than x", "greater than y", and "greater than z". Additionally, the phrase "from about 'x' to 'y'" (where 'x' and 'y' are numerical values) includes "from about 'x' to about 'y'".

[0034] It will be understood that such range formats are used for convenience and brevity, and thus should be interpreted flexibly to include not only the numerical values ​​explicitly set forth as limits of the ranges, but also all individual numerical values ​​contained within the ranges or subranges, where each numerical value and subrange is explicitly set forth. For example, a numerical range of "about 0.1 to 5%" should be interpreted to include not only the values ​​of about 0.1% to about 5% explicitly set forth, but also the individual values ​​(e.g., about 1%, about 2%, about 3%, and about 4%) and subranges (e.g., about 0.5% to about 1.1%; about 5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible subranges) within the indicated range.

[0035] The terms "about," "approximate," "at or about," and "substantially" as used herein mean that the amount or value in question may be or is exactly that value that will produce the same results or effects as disclosed in the claims or taught herein. That is, the amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as necessary, to produce the same results or effects, reflecting tolerances, conversion factors, rounding, measurement errors, and the like, and other factors known to those skilled in the art. In some circumstances, values ​​that will produce the same results or effects may not be reasonably determinable. In such cases, "about" and "approximately" as used herein are generally understood to mean a variation of ±10% of the nominal value indicated, unless otherwise stated or implied. In general, amounts, sizes, formulations, parameters, or other quantities or characteristics are "about," "approximately," or "nearly," whether or not expressly stated. When "about," "approximately," or "approximately" is used before a quantitative value, it is understood that the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0036] All percentages given herein are by volume unless otherwise specified. Temperatures given herein are at atmospheric pressure (i.e., 1 atmosphere) unless otherwise specified.

[0037] In this specification, difluoromethane (HFC-32, CH 2 F 2 ) and pentafluoroethane (HFC-125, C 2 F 5 Separation articles, e.g., films, membranes, etc., are described that separate at least one component from a gas mixture containing two or more components, including a fluorinated copolymer (H). The disclosed articles include a "selective layer" that is selectively permeable to the desired component to be separated from the gas mixture. The selective layer is composed of an amorphous fluorinated copolymer. Optionally, the article may include other layers that serve various purposes, e.g., a porous support layer, a "gutter layer" that allows the permeating gas to pass from the selective layer to the porous layer with minimal flow resistance, and a protective layer that protects the selective layer from contamination. The components of the separation articles described herein and methods for making and using them are described below.

[0038] [Amorphous fluorinated copolymer] The separation articles described herein include one or more amorphous fluorinated copolymers. In one embodiment, the amorphous fluorinated copolymers are produced by copolymerizing two or more fluorinated non-dioxolane cyclic monomers. The components of the copolymers and the method of production are described below.

[0039] [Fluorinated non-dioxolane cyclic monomers] In one embodiment, the fluorinated non-dioxolane cyclic monomer can have an olefin structure, the monomer having one or more carbon-carbon double bonds. In another embodiment, the fluorinated non-dioxolane cyclic monomer can be a conjugated or non-conjugated diene. In one embodiment, representative fluorinated cyclic monomers include, but are not limited to, one or more of the olefin compounds shown in Scheme 1 below, as well as combinations thereof.

[0040] In other embodiments, the fluorinated cyclic monomer may include one or more acyclic monomers that, upon polymerization, produce a fluorinated ring. For example, the third structure shown in Scheme 1 may cyclize upon polymerization to produce a five-membered ring.

[0041] Scheme 1: Fluorinated non-dioxolane cyclic monomers [ka] R 1 and R 2 are independently F, CF 3 , C.F. 2 CF 3 , C.F. 2 H, C.F. 2 CF 2 H, CFHCF 3 , CFHCF 2 H; R 3 and R 4 are independently F, CF 3 , or CF 2 CF 3 , C.F. 2 H, C.F. 2 CF 2 H, CFHCF 3 , CFHCF 2 H; and R 9 , F, CF 3 , or CF 2 CF 3 It is.

[0042] In one embodiment, the fluorinated non-dioxolane cyclic monomer has the structure: 1 and R 2 CF 3 In another embodiment, R 1 is F and R 2 CF 3 It is. [ka]

[0043] In another embodiment, the fluorinated non-dioxolane cyclic monomer is [ka] It is.

[0044] In one embodiment, the amorphous fluorinated copolymer is produced by copolymerization of two or more fluorinated non-dioxolane cyclic monomers. In another embodiment, the amorphous fluorinated copolymer is produced from at least two different fluorinated non-dioxolanes including perfluoro(butenyl vinyl ether) (PBVE), perfluoro(2,2-dimethyl-1,3-dioxole) and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD).

[0045] Scheme 2: Fluorinated non-dioxolane monomers [ka]

[0046] In one aspect, disclosed herein are amorphous copolymers formed by copolymerizing two or more monomers including PBVE and PDD, where (a) the PBVE monomer undergoes ring-closing polymerization to form 5- and 6-membered rings, and (b) the PDD and PBVE monomers are both randomly incorporated into the copolymer, and the PBVE comonomer is in an amount of about 20 mol% to about 90 mol%. In one aspect, the amount of PBVE used to form the copolymers described herein is 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 mol%, with any value being the lower or upper limit of the range (e.g., 40 mol% to 60 mol%, 45 mol% to 55 mol%, etc.).

[0047] In one embodiment, the amount of PDD used to produce the copolymers described herein is about 20 mol% to about 90 mol%, or about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 mol%, any value can be the lower or upper limit of the range (e.g., 40 mol% to 60 mol%, 45 mol% to 55 mol%, etc.). In another embodiment, the amorphous fluorinated copolymer consists only of perfluoro(butenyl vinyl ether) [PBVE] and perfluoro(2,2-dimethyl-1,3-dioxole) [PDD]. The structure of the resulting copolymer is shown in Scheme 3.

[0048] Scheme 3: PBVE-PDD copolymer [ka]

[0049] In one embodiment, the amorphous fluorinated copolymers described herein may be synthesized by solution polymerization or aqueous emulsion polymerization. In another embodiment, when using a solution method, a suitable solvent may be, for example, perfluorooctane, Vertrel® XF (CF 3 CFHCFHCF 2 CF 3 ), or Fluorinert® FC-43 (perfluorotri-n-butylamine). In another embodiment, when using the aqueous emulsion method, a suitable surfactant can be used. In one embodiment, the disclosed polymers can be polymerized optionally without any solvent. In yet another embodiment, the initiator can be selected from those commonly used for fluoropolymers, such as hydrocarbon peroxides, fluorocarbon peroxides, hydrocarbon peroxydicarbonates, and inorganic types such as persulfates.

[0050] In one embodiment, depending on the relative reactivities of the monomers used in the polymerization, they may be added as a single precharge, or they may need to be co-fed as a ratio-adjusted mixture to produce the desired copolymer composition.

[0051] In other embodiments, when the polymerization is deemed complete, the polymer may be isolated using methods known in the art. In one embodiment, in the case of a solution process, the solution (and unreacted monomers) may be removed by distillation at atmospheric or lower pressure. In some embodiments, since the polymers of the present disclosure are typically highly viscous and amorphous, more thorough drying is often required to remove residual solvent. In another embodiment, this may involve heating to 200-300° C. at atmospheric or lower pressure for 2-48 hours. In another embodiment, in the case of an aqueous emulsion process, the emulsion may be broken by several methods including freeze / thaw, addition of a strong mineral acid such as nitric acid, high shear mixing, or a combination of these methods.

[0052] The Examples provide non-limiting procedures for producing the copolymers described herein.

[0053] In one embodiment, the composition of the amorphous fluorinated copolymers used herein generally comprises: 19 F NMR spectroscopy. Furthermore, in this embodiment, the polymer is readily soluble in perfluorobenzene and deuterated in deuterobenzene (C 6 D 6) may be used to provide a lock signal. In a further embodiment, differential scanning calorimetry (DSC) may be used to measure the glass transition temperature (Tg) and the molecular weight distribution may be measured using gel permeation chromatography (GPC) on a styrene-divinylbenzene column using a perfluorinated solvent in combination with a multi-detector analysis module including refractive index, low angle light scattering and right angle light scattering detectors, or using other suitable equipment and / or methods known in the art. Optionally, in one embodiment, the type and concentration of end groups may be measured by pressing a film of the polymer and obtaining an infrared (IR) spectrum in transmission mode.

[0054] In one embodiment, the amorphous fluorinated copolymer may have a glass transition temperature of about 150° C. to about 260° C., or about 150° C., 175° C., 200° C., 225° C., 250° C., or 260° C., or any combination of the foregoing values, or a range including any of the foregoing values.

[0055] In yet other embodiments, the amorphous fluorinated copolymer is from about 10 kDa to about 2,000 kDa, or from 10 kDa, 50 kDa, 100 kDa, 150 kDa, 200 kDa, 250 kDa, 300 kDa, 350 kDa, 400 kDa, 450 kDa, 500 kDa, 550 kDa, 600 kDa, 650 kDa, 700 kDa, 750 kDa, 800 kDa, 850 kDa, 900 kDa, 950 kDa, 1,000 kDa, 1,050 kDa, 1,100 kDa, Da, 1,150 kDa, 1,200 kDa, 1,250 kDa, 1,300 kDa, 1,350 kDa, 1,400 kDa, 1,450 kDa, 1,500 kDa, 1550 kDa, 1,600 kDa, 1,650 kDa, 1,700 kDa, 1,750 kDa, 1,800 kDa, 1,850 kDa, 1,900 kDa, 1,950 kDa, or 2,000 kDa, or a combination of the above values, or a range including any of the above values.

[0056] In yet another embodiment, the amorphous fluorinated copolymer has a molecular weight of from about 10,000 g / mol to about 3,000,000 g / mol, or from 10,000 g / mol, 50,000 g / mol, 100,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, 600,000 g / mol, 700,000 g / mol, 800,000 g / mol, 900,000 g / mol, 1,000,000 g / mol, 1,100,000 g / mol, 1,200,000 g / mol, 1,300,000 g / mol, 1,400,000 g / mol, 1,500 ,000 g / mol, 1,600,000 g / mol, 1,700,000 g / mol, 1,800,000 g / mol, 1,900,000 g / mol, 2,000,000 g / mol, 2,100,000 g / mol, 2,200,000 g / mol, 2,300,000 g / mol, 2,400,000 g / mol, 2,500,000 g / mol, 2,600,000 g / mol, 2,700,000 g / mol, 2,800,000 g / mol, 2,900,000 g / mol, or 3,000,000 g / mol, or any combination of or ranges inclusive of any of the foregoing values. w ).

[0057] In another embodiment, the amorphous fluorinated copolymer has a PBVE content of 40 mol% to 60 mol% and a PDD content of 40 mol% to 60 mol%, a weight average molecular weight (M) of about 250,000 g / mol to about 350,000 g / mol. w ), and a number average molecular weight (M n ).

[0058] [Separated items and their application] Described herein is a separation article comprising or formed from an amorphous fluorinated copolymer. In one embodiment, the article is a multi-layered article, and at least one layer of the structure comprises or is formed from the copolymer described herein. In another embodiment, the article can be a film, membrane, tube, or fiber.

[0059] In yet another embodiment, the article may include a layer or coating of an amorphous fluorinated copolymer. In one embodiment, the layer or coating has a thickness of 1 μm or less, or a thickness of about 950, 900, 850, 800, 750, 700, 650, 600, 550, or about 500 nm or less, or any combination of these values, or any range including any of these values. In another embodiment, the layer or coating has a thickness of about 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, or 1 μm, or any combination of these values, or any range including any of these values.

[0060] In yet another embodiment, the amorphous fluorinated copolymer may be formed or molded into any shape necessary or desired for use as a separation article. There are many known methods for forming the copolymer selected for the selective layer into a single or multiple layer film or membrane. In some embodiments, the selective layer may comprise an unsupported film, tube, or fiber of the amorphous fluorinated copolymer as a single layer membrane. In some embodiments, an unsupported film may be too thick to allow the desired gas flow through the membrane. Thus, in some embodiments, the membrane may comprise a very thin selective layer of the amorphous fluorinated copolymer located on top of (i.e., adjacent to or in contact with) a support structure having a much greater permeability. For example, in one embodiment, the membrane may comprise an integral asymmetric membrane in which a denser selective layer is located on top of a microporous support layer. Such membranes were originally developed by Loeb and Sourirajan, and the manufacture of flat sheet or hollow fiber membranes is described, for example, in U.S. Pat. No. 3,133,132 to Loeb and U.S. Pat. No. 4,230,463 to Henis and Tripodi, the disclosures of which are incorporated herein by reference.

[0061] In some embodiments, the membrane may include multiple layers, including at least one selective layer, each layer serving a different purpose. Further in this embodiment, such a multi-layer composite membrane may have a microporous support layer that provides mechanical strength. In other embodiments, the multi-layer membrane may include a non-porous, but highly permeable "gutter" layer, for example coated on (i.e. adjacent to) the microporous support layer. Further in this embodiment, this gutter layer may not be generally selective, but instead may form a smooth surface on which to deposit a very thin selective layer that performs the membrane's primary selective function. In another embodiment, the gutter layer may direct the permeating gas to the pores of the support layer. In additional embodiments, the selective layer may be covered by a protective layer. In one embodiment, the primary purpose of the protective layer is to prevent fouling of the selective layer, such as by certain components of the gas stream. In some embodiments, the disclosed multi-layer structures may be formed by solution casting, but are not necessarily formed by it. General manufacturing techniques for making composite membranes of this type are described, for example, in U.S. Patent No. 4,243,701 to Riley et al., the disclosure of which is incorporated herein by reference. In one aspect, disclosed herein is a gas separation membrane including a feed side and a permeate side, the separation membrane having a selective layer comprising or consisting of the copolymers disclosed herein.

[0062] In one embodiment, the multi-layer composite membrane may be in the form of a flat sheet, a tube, or a hollow fiber. In the hollow fiber form, in one embodiment, the multi-layer composite membrane may be formed with the amorphous fluorinated copolymers described herein, for example, using the coating methods taught in U.S. Patent Nos. 4,863,761, 5,242,636, and 5,156,888, or using the double capillary spinneret shown in U.S. Patent Nos. 5,141,642 and 5,318,417, the disclosures of which are incorporated herein by reference. In one embodiment, a plurality of hollow fibers may be contained in a separation unit.

[0063] In other embodiments, the thickness of the selective layer of the membrane can be determined based on one or more parameters of the separation process. In one embodiment, the thickness of the selective layer of the membrane is less than about 1 μm. In other embodiments, the selective layer can be thinner, for example, the selective layer can be 0.5 μm or less. In one embodiment, the selective layer has a flow rate of at least 100 GPU (1 GPU=1×10) as measured in pure hydrogen gas at 25° C. -6 cm 3 (STP) / cm 2 The membrane should have a sufficiently thin thickness so that it can provide a pressure-normalized flux (permeation flux per pressure difference) of 100 s cm Hg, preferably at least 400 GPU.

[0064] In one aspect, the separation articles described herein are mechanically robust, and also have high thermal stability and high chemical resistance. In another aspect, the amorphous fluorinated copolymers described herein that form the selective layer are typically soluble only in perfluorinated solvents. In yet another aspect, they are typically stable for many years when immersed in acids, alkalis, oils, low molecular weight esters, ethers and ketones, aliphatic and aromatic hydrocarbons, and oxidizing agents. In yet another aspect, they are also thermally stable for many years at temperatures below the glass transition temperature.

[0065] In one embodiment, the separation articles described herein may be used in any suitable device. For example, the membranes are typically prepared in any known form and used in a modular form that includes the membranes housed in any suitable type of housing and separation unit. Any number of membrane modules may be used in combination (e.g., in series or parallel) to process a gas stream. The number of membrane modules may be based on one or more factors including, for example, the required or desired flow rate, the composition of the stream, and other operating parameters of the separation process. In a separation process, in one embodiment, the membrane is exposed to a flowing gaseous feed composition that includes a gas mixture. In another embodiment, the gas flow is caused by a pressure differential across the membrane, either by pressurizing the feed / retentate side of the membrane or by applying a vacuum to the permeate side of the membrane. Separation of the components of the gas stream, in one embodiment, occurs through the membrane, resulting in a gas stream with a composition enriched in the more permeable component of the gas mixture. Conversely, in another embodiment, the gas stream exiting the module on the feed / retentate side of the membrane has a composition that is lean to the more permeable component of the gas mixture and enriched in the less permeable component(s) of the gas mixture.

[0066] In one aspect, the disclosure relates to an apparatus and method for separating at least one component from a gas mixture. In another aspect, the disclosed apparatus includes a separation article (e.g., a membrane) as described herein having a "selective layer" configured to be selectively permeable to a predetermined component to be separated from the gas mixture. Optionally, in one aspect, the membrane may include one or more other layers that serve various purposes, such as a porous support layer, a "gutter layer" that allows the passage of gas permeants from the selective layer to the porous layer with minimal flow resistance, and a protective layer that protects the selective layer from fouling.

[0067] The separation articles described herein are useful in the field of gas separation. In one embodiment, disclosed herein is a method for separating a first gas component from a gas mixture, the method comprising passing the gas mixture through a separation article described herein. In one embodiment, the separation article is a membrane having a selective layer made of an amorphous fluorinated copolymer described herein. In some embodiments, the amorphous fluorinated copolymer can be solution cast onto the layer to produce a selective layer. In one embodiment, the amorphous fluorinated copolymer can be dissolved in one or more solvents. Conversely, crystalline fluoropolymers that usually have negligible solubility in solvents are not preferred. In another embodiment, crystalline polymers usually have low gas permeability compared to amorphous polymers.

[0068] In one embodiment, the separation articles described herein are capable of separating difluoromethane (HFC-32, CH) from a gas mixture. 2 F 2 ), the gas mixture comprising HFC-32 and one or more additional fluorinated gases. In one embodiment, the separation articles described herein are effective for removing pentafluoroethane (HFC-125, C 2 F 5 H) without removing difluoromethane (HFC-32, CH 3 F) is effective in removing

[0069] Without wishing to be bound by any particular theory, the amorphous fluorinated copolymers present in the separation articles described herein have high permeability to HFC-32, but not to other fluorinated gases, such as HFC-125. In one embodiment, the amorphous fluorinated copolymer has an ideal selectivity for HFC-32 over HFC-125 of about 5 to about 50, or 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50, any of which can be the lower and upper limits of the range (e.g., 20 to 35). In other embodiments, the amorphous fluorinated copolymer has a diffusivity of HFC-32 to HFC-125 of about 10 to about 200, or 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200, any of which can be the lower or upper limit of the range (e.g., 50 to 100).

[0070] In one embodiment, a method for separating a first component from a gas mixture includes introducing a feed stream comprising the gas mixture to the disclosed membrane. Further, in the embodiment, the membrane has a first side, a second side, and a selective layer selectively permeable to the first component. That is, the first component has a greater permeability through the selective layer than other components of the gas mixture. In one embodiment, the feed stream is introduced to the first side of the membrane. Further, in this embodiment, a driving force (e.g., a pressure differential) drives at least a portion of the gas mixture from the first side to the second side of the membrane, resulting in a permeate stream on the second side of the membrane. In a further embodiment, the resulting permeate stream is enriched in the first component. In another embodiment, a retentate or residue stream depleted in the first component can be recovered from the first side of the membrane.

[0071] In one embodiment, in the gas separation method disclosed herein, the method comprises at least the following steps: (a) passing a gas mixture through a separation article having a feed side and a permeate side, the separation article having a selective layer that is selectively permeable to at least a first gas component, the selective layer comprising an amorphous fluorinated copolymer; and (b) providing a driving force sufficient to permeate at least a portion of the gas mixture across the membrane from the feed side to the permeate side of the separation membrane, resulting in a gas permeate stream on the permeate side of the separation membrane and a gas retentate stream on the feed side of the separation membrane, the gas permeate stream comprising the first gas component.

[0072] In another embodiment, the permeate stream has a concentration of the first component that is greater than the concentration of the first component in the retentate stream.

[0073] In yet another aspect, the method includes removing a permeate stream from the permeate side of the separation article. In a further aspect, the method further includes removing a retentate stream from the feed side of the separation article.

[0074] In one embodiment, the gas mixture comprises one or more fluorinated refrigerant gases. In another embodiment, the gas mixture comprises an azeotropic or near azeotropic gas mixture. In another embodiment, the gas mixture comprises an azeotropic or near azeotropic gas mixture, one or more of the components of which are fluorinated refrigerants. In another embodiment, the gas mixture comprises a mixture of difluoromethane (HFC-32, CH 2 F 2 ) and pentafluoroethane (HFC-125, C 2 F 5 H). In one embodiment, the articles and methods described herein are effective in removing HFC-32 from a mixture comprising HFC-32 and HFC-125. In one embodiment, greater than about 50, 55, 60, 65, 70, 76, 80, 86, 90, or greater than about 95% of the HFC-32 in the gas mixture permeates the selective layer of the separation article and is removed from the gas mixture.

[0075] [Aspects] Aspect 1: A separation article comprising a first surface and a second surface and a selective layer adjacent to at least one of the first surface or the second surface, the selective layer being adapted to separate difluoromethane (HFC-32, CH) from a gas mixture. 2 F 2 36. A separation article comprising an amorphous fluorinated copolymer for selectively removing a fluorinated moiety.

[0076] Aspect 2: The separation article of aspect 1, wherein the amorphous fluorinated copolymer is produced by copolymerizing two or more fluorinated non-dioxolane cyclic monomers.

[0077] Aspect 3: The fluorinated non-dioxolane cyclic monomer comprises two or more of the following compounds: [ka] 3. The discrete article of claim 2, comprising: [In formula: R 1 and R 2 are independently F, CF 3 , C.F. 2 CF 3 , C.F. 2 H, C.F. 2 CF 2 H, CFHCF 3 , CFHCF 2 H; R 3 and R 4 are independently F, CF 3 , or CF 2 CF 3 , C.F. 2 H, C.F. 2 CF 2 H, CFHCF 3 , CFHCF 2 H; and R 9 , F, CF 3 , or CF 2 CF 3 It is.]

[0078] Aspect 4: The separation article of aspect 1, wherein the amorphous fluorinated copolymer comprises a copolymer of perfluoro(butenyl vinyl ether) [PBVE] and perfluoro(2,2-dimethyl-1,3-dioxole) [PDD].

[0079] Aspect 5: The separation article of aspect 4, wherein the amorphous fluorinated copolymer has a PBVE content of about 20 mol% to about 90 mol% and a PDD content of about 20 mol% to about 90 mol%.

[0080] Aspect 6: The separation article of aspect 4, wherein the amorphous fluorinated copolymer has a PBVE content of about 40 mol% to about 60 mol% and a PDD content of about 40 mol% to about 60 mol%.

[0081] Aspect 7: The separation article of aspect 1, wherein the selective layer is an amorphous fluorinated copolymer consisting of perfluoro(butenyl vinyl ether) [PBVE] and perfluoro(2,2-dimethyl-1,3-dioxole) [PDD].

[0082] Embodiment 8: The separated article of any one of embodiments 1 to 7, wherein the amorphous fluorinated copolymer has a glass transition temperature of about 150°C to about 260°C.

[0083] Aspect 9: The separation article of any one of aspects 1 to 8, wherein the amorphous fluorinated copolymer has a number average molecular weight (Mn) of about 10 kDa to about 2,000 kDa.

[0084] Embodiment 10: The separation article of any one of embodiments 1 to 9, wherein the amorphous fluorinated copolymer has a weight average molecular weight (Mw) of about 10,000 g / mol to about 3,000,000 g / mol.

[0085] Aspect 11: The separation article of any one of aspects 1 to 10, wherein the gas mixture comprises difluoromethane (HFC-32) and pentafluoroethane (HFC-125).

[0086] Example 12: The separation article of any one of Examples 1 to 11, wherein the amorphous fluorinated copolymer has an ideal selectivity for HFC-32 over HFC-125 of about 5 to about 50.

[0087] Example 13: The separation article of any one of Examples 1 to 11, wherein the amorphous fluorinated copolymer has a diffusivity ratio of HFC-32 to HFC-125 of about 10 to about 200.

[0088] Embodiment 14: The separation article of any one of embodiments 1 to 13, wherein the article comprises a film, a membrane, a tube, or a fiber.

[0089] Embodiment 15: The separation article of embodiment 14, wherein the article comprises a coating of the amorphous fluorinated copolymer.

[0090] Embodiment 16: The separation article of any one of embodiments 1-13, wherein the article comprises an asymmetric membrane comprising an amorphous fluorinated copolymer adjacent to a microporous support layer.

[0091] Example 17: The separation article of any one of Examples 1 to 13, wherein the article has an asymmetric membrane comprising an amorphous fluorinated copolymer adjacent to a gutter layer, the gutter layer adjacent to a microporous support layer.

[0092] Example 18: A separation article of any one of Examples 1 to 13, wherein the article has a membrane unit comprising a plurality of hollow fiber membranes, the membrane unit having a feed side and a permeate side, and the hollow fibers comprise an amorphous fluorinated copolymer.

[0093] Aspect 19: A method for separating a first gas component from a gas mixture comprising two or more fluorinated gases, the method comprising passing the gas mixture through a separation article described in any one of aspects 1-18, wherein the gas mixture contacts the selective layer.

[0094] Example 20: The method of example 19, comprising: (a) passing a gas mixture through a separation article having a feed side and a permeate side, the separation article having a selective layer that is selectively permeable to at least a first gas component, the selective layer comprising an amorphous fluorinated copolymer; (b) providing a driving force sufficient to permeate at least a portion of the gas mixture from the feed side to the permeate side of the separation article, resulting in a gas permeate stream at the permeate side of the separation article and a gas retentate stream at the feed side of the separation article, the gas permeate stream comprising the first gas component.

[0095] Aspect 21: The gas mixture is difluoromethane (HFC-32, CH 2 F 2 ) and pentafluoroethane (HFC-125, C 2 F 5 21. The method according to claim 19 or 20, comprising:

[0096] Aspect 22: Difluoromethane (HFC-32, CH) from a gas mixture 2 F 2 22. The method of embodiment 21, wherein said first and second nucleotide sequences are selectively removed. EXAMPLES

[0097] The following examples are provided to provide those skilled in the art with a full disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated, and are intended to be merely illustrative of the disclosure and are not intended to limit the scope of what the inventors regard as their disclosure. Efforts have been made to ensure accuracy with respect to numerical values ​​(e.g., amounts, temperatures, etc.), but some errors and deviations should be accounted for. Unless otherwise specified, parts are parts by weight, temperature is in ° C. or is at room (or ambient) temperature, and pressure is at or near atmospheric pressure.

[0098] [Example 1] Synthesis of PDD-co-PBVE copolymer [ka]

[0099] Perfluorooctane solvent (480 mL, 854 g) was added to a Duran glass jar (1000 mL) with a magnetic stir bar. The lid was attached and a valve for argon source and vacuum (30 Torr) was connected. The solvent was degassed using four cycles of vacuum / argon backfill. Freshly distilled PDD (35.0 mL, 56.0 g) was added via syringe, followed by the addition of PBVE comonomer (35.0 mL, 44.7 g). The polymerization was carried out using hexafluoropropylene oxide dimer peroxide (HFPO-DP, [CF 3 CF 2 CF 2 OCF(CF 3 )COO] 2 The reaction was started by adding the solvent (3.0 mL, 0.16 M in Vertrel XF). The solvent was completely gelled by stirring for 20 h at 22° C. The gel was dried in a vacuum oven (275° C., 200 mTorr) for 15 h to give 55 g of a white copolymer. 19 The composition was 81 / 19 mol% PDD / PBVE as determined by F NMR (Figure 1). The Tg was measured to be 182 °C by DSC. Mn = 220,000 g / mol and Mw = 297,000 g / mol by GPC using perfluorooctane. By varying the amount of PDD and PBVE, copolymers with different PDD and PBVE contents were synthesized.

[0100] [Example 2] Single gas permeability of HFC-32 and HFC-125 in 50%PBVE / 50%PDD The permeabilities (or permeability coefficients) of HFC-32 and HFC-125 were measured using a static membrane apparatus and the pressure rise method. A schematic diagram of the permeability measurement apparatus is shown in Figure 2. The apparatus consisted of a H 2The sample was placed in a fume hood equipped with a molecular sieve dryer (WA Hammond Drierite Company Ltd., L68NP303) to remove O. A vacuum / turbo pump (Pfeiffer HiCube 80 Eco, HiPace 80 Turbo Pump with TC 110, DN 63 ISO-K) was used to apply a low vacuum (10 -4 The apparatus was placed in a fume hood to degas the sample and the sample at 293.15 torr. The temperature control system (Cal Controls 3300 Series Temperature Controller) was capable of heating and measuring the temperature of the sample at 293.15 to 373.15 K.

[0101] The static membrane device measures the permeability coefficient of gas through a polymer film bonded to a brass disk containing a hole of known area (1.28 cm 2 ) to which a polymer film of known thickness is adhered using an epoxy instant adhesive. The thickness of the polymer film is measured using a digital micrometer (Starrett Digital IP67 Outside Micrometer, No. 796.1). When the apparatus is assembled, the brass disk with the adhesive film is placed on a sintered metal support disk. The bottom side of the sintered metal disk is the downstream side of the apparatus and has a known volume that is used in the permeability calculation formula. The downstream volume was measured by adding a liquid of known mass and density to the downstream side to obtain the volume. The permeability of a species through the polymer film is calculated using Equation (1):

number

[0102] The fluoropolymer was first treated with an etching solution (FluoroEtch®, a safety solvent) to improve adhesion to the brass disk. Single gas permeability data was collected for both HFC-32 and HFC-125 at 35° C. and 2 bar, as shown in FIG. 3. Permeation tests were run until steady state permeation was reached. The permeability results for HFC-32 and HFC-125 in the 50% PBVE / 50% PDD copolymer film are listed in Table 1 and show a high selectivity of 28±7.

[0103] [Table 1]

[0104] [Example 3] Single gas permeability of HFC-32 and HFC-125 through PBVE-co-PDD with various compositions The pure gas permeabilities (permeability coefficients) of HFC-32 and HFC-125 were measured for five different compositions of PBVE-co-PDD membranes (89 / 11%, 50 / 50%, 30 / 70%, 5 / 95%, and 100 / 0%), as shown in Figure 3. The ratio of permeability of HFC-32 to HFC-125 (i.e., ideal selectivity) was highest at the 50% PDD composition and decreased at lower and higher PDD ratios.

[0105] [Example 4] Effect of temperature on single gas permeability of HFC-32 and HFC-125 in 50% PDD / 50% PBVE The single gas permeability of HFC-32 and HFC-125 in 50% PDD / 50% PBVE was measured at 50° C. The same procedure as in Example 2 was used to measure the single gas permeability at various temperatures. The apparatus was heated at the measurement temperature for at least 10 minutes for at least 12 hours before permeability measurements were performed on the measurement film. -4 The column was evacuated to a pressure of 1000 torr. The temperature dependence of the permeability is shown in Table 2, which shows that there is no significant change in the selectivity even with increasing temperature.

[0106] [Table 2]

[0107] [Example 5] Single gas permeability of HFC-32 and HFC-125 in varying compositions of PBVE-co-PDD The permeabilities of HFC-32 and HFC-125 in polymer films consisting of 100% PBVE, 89% PBVE-11% PDD, 50% PBVE-50% PDD, 30% PBVE-70% PDD, and 5% PBVE-95% PDD were measured and are shown in Figure 3 and Table 3.

[0108] The ideal selectivity is the ratio of the permeability of HFC-32 divided by the permeability of HFC-125. HFC-32 / HFC-125 The ideal selectivity maximum, where β is about 28, is obtained at the 50% PBVE-50% PDD copolymer composition, as shown in FIG.

[0109] [Table 3]

[0110] [Example 6] Selectivity of HFC-32 and HFC-125 gas mixtures in PBVE-co-PDD polymers The selectivity of the HFC-32 and HFC-125 mixed gases for 50 mol% PBVE-50 mol% PDD and other PBVE-co-PDD polymers was measured by gluing a small piece of the membrane onto a brass disk and mounting it in the mixed gas permeation apparatus shown in Figure 5. Samples were left to stand for at least 10 min for 12 h to remove volatile impurities. -4 The system was evacuated to 1000 rpm for 10 min. The upstream face pressure of the system was maintained at a constant pressure of about 10 bar by flowing R-410A over the membrane surface to keep the upstream composition of HFC-32 and HFC-125 constant. The resulting retentate was then conditioned for HFC-32 and HFC-125 analysis and measured by mass spectrometry (Hiden Isochema Ltd., IGA 003, Warrington, United Kingdom). The analysis was carried out for 4 days to ensure selectivity stability. The selectivity results for the gas mixtures are shown in Table 4. The measured selectivity for the gas mixtures of the tested compositions is in particular agreement with the calculated ideal selectivity for HFC-32 / HFC-125 shown in Table 3.

[0111] [Table 4]

[0112] [Example 7] Solubility of HFC-32 and HFC-125 in PBVE-co-PDD Gas absorption of HFC-32 and HFC-125 into the polymer films was measured using a gravimetric microbalance (Hiden Isochema Ltd., IGA 003, Warrington, United Kingdom). The gravimetric microbalance can measure the change in mass of the sample as a function of gas composition, temperature, or pressure, allowing the determination of kinetic parameters and adsorption equilibria. 6 The instrumentation and theory of the gravimetric microbalance have been described in detail in the previous publication, with some modifications to the procedure. 7 Rectangular strips (4 cm × 1 cm) of polymer film (300 mg) were attached to small copper hooks and suspended from tungsten hanging wires. The samples were then stored in vacuum (10 °C) at the measurement temperature for 24 h to remove any residual moisture or volatile impurities. -10 The samples were degassed under 1000 psi (200 MPa). Each pressure point was completed for the shortest required time of 12 h to establish thermodynamic equilibrium. Equilibrium stability and dynamic adsorption profile were measured by HISOrp software program. The microbalance can be operated in two different modes: static or dynamic. In static mode, gas is evacuated from the sample using inlet and outlet valves and the pressure is kept constant. In dynamic mode, the set pressure is controlled by the outlet valve and a continuous flow of gas passes through the sample. 6In these experiments, the equilibria were operated in static mode. A jacketed water bath was used to control the temperature of the samples, and the temperatures of the samples and counterweights were measured with type K in-situ thermocouples with an accuracy of ±0.1 K. The thermocouples were calibrated using platinum resistance thermometers (Hart Scientific SPRT model 5699 and a readout Hart Scientific Blackstack model 1560 with SPRT module 2560) with an accuracy of ±0.005 K. The analytical resolution of the IGA microbalance is 0.0001 mg for absorption and desorption measurements at a given temperature and pressure. 6 The adsorption isotherms of HFC-125 and HFC-32 in PBVE and PBVE-co-PDD films were measured.

[0113] From the adsorption data of the permeant gas in the polymer film, the solubility of each permeant is calculated according to the formula:

number

[0114] Using equation (3), the solubility of each penetrant in each film is plotted against pressure. The solubility coefficient S, which is the solubility at infinite dilution, is ∞ is defined as follows:

number

[0115] The solubility of HFC-32 and HFC-125 in PBVE-co-PDD polymers as a function of PDD content is shown in Figure 6. Increasing the amount of PDD increases the solubility of the penetrants. The solubility of HFC-32 and HFC-125 is shown in Table 5.

[0116] [Table 5]

[0117] [Example 8] Diffusivity of HFC-32 and HFC-125 in PBVE-co-PDD polymer Since permeability is a function of solubility and diffusivity, time-dependent absorption data for HFC-32 and HFC-125 in polymer films were collected at 308.15 K and 0.2 MPa using a gravimetric microbalance. The diffusivity is given by Equation (4):

number

[0118] In applicant's analysis, the following assumptions were made to describe the system. (1) The penetrating species dissolves by a one-dimensional (horizontal) diffusion process. (2) A thin boundary layer exists at the interface between the penetrating species and the polymer film, where a saturation concentration quickly forms. (3) The interaction between the penetrating species and the polymer film is physical.

[0119] Based on these assumptions, the following boundary and initial conditions are applied to describe the system:

number

number

number

[0120] Although equation (9) contains infinite sum terms, the first 20 terms provide sufficient numerical accuracy. With the goal of predicting the diffusion coefficient of a species in a polymeric material at a specific temperature and pressure, nonlinear regression is used to fit a diffusion model to the experimentally obtained concentrations. The best fit parameters in the regression are used to define the equilibrium concentration (CS) and the diffusion coefficient (D).

[0121] The diffusivities of HFC-32 and HF5-125 are shown as a function of PDD composition in Table 6. In general, the diffusivities increase with increasing PDD content, but the ratio of the diffusivity of HFC-32 to that of HFC-125 (D HFC-32 / D HFC-125 ) was the largest in the 50mol%PBVE-50mol%PDD composition, and the maximum value D HFC-32 / D HFC-125 This suggests separation driven by the diffusion rate ratio given by =83.8±3.8.

[0122] [Table 6]

[0123] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many modifications and variations can be made to the above-described embodiments without substantially departing from the concepts and principles of the disclosure. All such modifications and variations are intended to be included within the scope of the present disclosure and protected by the following claims.

[0124] [References] (1) Kyoto Protocol - Targets for the First Commitment Period. UNFCCC https: / / unfccc.int / process-and-meetings / the-kyoto-protocol / what-is-the-kyoto-protocol / kyoto-protocol-targets-for-the-first-commitment-period (Accessed January 11, 2021) (2)Mota-Babiloni, A.; Navarro-Esbri, J.; Barragan-Cervera, A.; Moles, F.; Peris, B. Analysis Based on EU Regulation No 517 / 2014 of New HFC / HFO Mixtures as Alternatives of High GWP Refrigerants in Refrigeration and HVAC Systems. International Journal of Refrigeration. 2015. https: / / doi.org / 10.1016 / j.ijrefrig.2014.12.021. (3) EPA. Protecting Our Climate by Reducing Use of Hydrofluorocarbons Proposed Rule-Phasedown of Hydrofluorocarbons: Establishing the Allowance Allocation and Trading Program under the American Innovation and Manufacturing Act of 2021. (4)Pardo, F.; Zarca, G.; Urtiaga, A. Effect of Feed Pressure and Long-Term Separation Performance of Pebax-Ionic Liquid Membranes for the Recovery of Difluoromethane (R32) from Refrigerant Mixture R410A. Journal of Membrane Science 2021, 618, 118744. https: / / doi.org / 10.1016 / j.memsci.2020.118744. (5)IIF-IIR; V., M.; D., C.; L., DJ. The Impact of the Refrigeration Sector on Climate Change. 35th Informatory Note on Refrigeration Technologies.; IIF-IIR, 2017. (6)Shiflett, MB; Yokozeki, A. Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids: [Bmim][PF6] and [Bmim][BF4]. Industrial and Engineering Chemistry Research, 2005, 44 (12), 4453-4464. https: / / doi.org / 10.1021 / ie058003d. (7)Minnick, DL; Turnaoglu, T.; Rocha, MA; Shiflett, MB. Review Article: Gas and Vapor Sorption Measurements Using Electronic Beam Balances. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2018, 36 (5), 050801. https: / / doi.org / 10.1116 / 1.5044552.

Claims

1. A separation article comprising a first surface and a second surface and a selective layer adjacent to at least one of the first surface or the second surface, the selective layer being adapted to separate difluoromethane (HFC-32, CH4) from a gas mixture. ２ F ２ 23. A separation article comprising an amorphous fluorinated copolymer for selectively removing a fluorinated moiety.

2. 10. The separation article of claim 1, wherein the amorphous fluorinated copolymer is produced by copolymerizing two or more fluorinated non-dioxolane cyclic monomers.

3. The fluorinated non-dioxolane cyclic monomers are comprised of two or more of the following compounds: 【Chemistry 1】 [In the formula: R １ and R ２ are independently F, CF ３ , C.F. ２ CF ３ , C.F. ２ H, C.F. ２ CF ２ H, CFHCF ３ , C.F.H.F. ２ H; R ３ and R ４ are independently F, CF ３ , or C.F. ２ CF ３ , C.F. ２ H, C.F. ２ CF ２ H, CFHCF ３ , C.F.H.F. ２ H; and R ９ , F, CF ３ , or C.F. ２ CF ３ It is.] The separation article of claim 2 comprising:

4. 2. The separation article of claim 1, wherein the amorphous fluorinated copolymer comprises a copolymer of perfluoro(butenyl vinyl ether) [PBVE] and perfluoro(2,2-dimethyl-1,3-dioxole) [PDD].

5. 5. The separation article of claim 4, wherein the amorphous fluorinated copolymer has a PBVE content of about 20 mol % to about 90 mol % and a PDD content of about 20 mol % to about 90 mol %.

6. 5. The separation article of claim 4, wherein the amorphous fluorinated copolymer has a PBVE content of about 40 mol % to about 60 mol % and a PDD content of about 40 mol % to about 60 mol %.

7. 10. The separation article of claim 1, wherein the selective layer is an amorphous fluorinated copolymer of perfluoro(butenyl vinyl ether) [PBVE] and perfluoro(2,2-dimethyl-1,3-dioxole) [PDD].

8. 10. The separation article of claim 1, wherein the amorphous fluorinated copolymer has a glass transition temperature of about 150°C to about 260°C.

9. 10. The separation article of claim 1, wherein the amorphous fluorinated copolymer has a number average molecular weight (Mn) of about 10 kDa to about 2,000 kDa.

10. 10. The separation article of claim 1, wherein the amorphous fluorinated copolymer has a weight average molecular weight (Mw) of about 10,000 g / mol to about 3,000,000 g / mol.

11. 10. The separation article of claim 1, wherein the gas mixture comprises difluoromethane (HFC-32) and pentafluoroethane (HFC-125).

12. 10. The separation article of claim 1, wherein the amorphous fluorinated copolymer has an ideal selectivity for HFC-32 over HFC-125 of about 5 to about 50.

13. 2. The separation article of claim 1, wherein the amorphous fluorinated copolymer has a diffusivity ratio of HFC-32 to HFC-125 of about 10 to about 200.

14. The separation article of claim 1 , wherein the article comprises a film, a membrane, a tube, or a fiber.

15. The separation article of claim 14 , wherein the article comprises a coating of the amorphous fluorinated copolymer.

16. 10. The separation article of claim 1, wherein the article comprises an asymmetric membrane comprising an amorphous fluorinated copolymer adjacent to a microporous support layer.

17. 10. The separation article of claim 1, wherein the article has an asymmetric membrane comprising an amorphous fluorinated copolymer adjacent to a gutter layer, the gutter layer adjacent to a microporous support layer.

18. 10. The separation article of claim 1, wherein the article comprises a membrane unit comprising a plurality of hollow fiber membranes, the membrane unit having a feed side and a permeate side, the hollow fibers comprising an amorphous fluorinated copolymer.

19. 19. A method for separating a first gas component from a gas mixture comprising two or more fluorinated gases, the method comprising passing the gas mixture through a separation article according to any one of claims 1 to 18, wherein the gas mixture contacts a selective layer.

20. (a) passing a gas mixture through a separation article having a feed side and a permeate side, the separation article having a selective layer selectively permeable to at least a first gas component, the selective layer comprising an amorphous fluorinated copolymer; (b) providing a driving force sufficient to permeate at least a portion of the gas mixture from the feed side to the permeate side of the separation article, resulting in a gas permeate stream at the permeate side of the separation article and a gas retentate stream at the feed side of the separation article, the gas permeate stream comprising the first gas component; 20. The method of claim 19, comprising:

21. The gas mixture is composed of difluoromethane (HFC-32, CH ２ F ２ ) and pentafluoroethane (HFC-125, C ２ F ５ H).

22. Difluoromethane (HFC-32, CH ２ F ２ 22. The method of claim 21 , wherein the first and second ions are selectively removed.

Images