Carbon molecular sieve membranes, methods of manufacturing, and use thereof

Abstract

A method of manufacturing a laminate carbon molecular sieve (CMS) membrane may comprise forming a polyvinylidene chloride copolymer into two or more microcapillary films; arranging the two or more microcapillary films into a microcapillary laminate comprising two or more widthwise spacers interposed between each of the two or more microcapillary films; pretreating the two or more microcapillary films by heating at a first temperature of from 120 ℃ to 200 ℃; pyrolyzing the two or more microcapillary films at a second temperature of from 600 ℃ to 700 ℃, wherein the arranging step occurs before or after the pyrolyzing step; annealing the microcapillary laminate at a third temperature of from 900 ℃ to 1700 ℃ with inert gas or under vacuum; and either oxidizing the microcapillary laminate with air or carbon dioxide to form the CMS membrane.

Description

CARBON MOLECULAR SIEVE MEMBRANES, METHODS OF MANUFACTURING, AND USE THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 661,314 filed June 18, 2024, the contents of which are incorporated in their entirety herein.FIELD

[0002] The present disclosure relates to the field of gas separation using a carbon molecular sieve membranes. More particularly, it relates to methods of producing carbon molecular sieve membranes, particularly laminate membranes, for the separation of gases, as well as methods for the separation of gases from a gaseous mixture by passing the gaseous mixture through the laminate membranes, as detailed herein.BACKGROUND

[0003] In the chemical industry, decarbonization technologies are continually being developed due to carbon dioxide (CO2) emissions being a source of global climate change. Particularly, Burning of fossil fuels (coal, methane, oil) contribute to CO2 generation and global warming. Carbon dioxide from flue gas may also be a major source of carbon dioxide emissions in other processes.SUMMARY

[0004] Accordingly, methods are desired which can separate carbon dioxide from nitrogen, such as in flue gas. Retrofitting of CO2 capture units into the existing flue gases, also known as post-combustion CO2 capture, is one potential solution. However, challenges exist as to the large volume of flue gas and low concentration of CO2, which leads to large capital investment.

[0005] Carbon molecular sieves (CMS) membranes are one such means that have traditionally been used to separate gas mixtures. CMS membranes may be prepared from a variety of resins in hollow fiber or film orientations. These fibers or films may be pyrolyzed at various temperatures and conditions. The pyrolysis reduces the resins in the fibers or films to carbon, but maintains at least some porosity in the pyrolyzed product, often in the form of micropores.

[0006] The fibers or films thus formed may then be bundled or stacked as appropriate and used in conventional gas separations equipment employing adsorption of particular gases. For example, gas mixtures may be flowed across the fibers and films, i.e., through the CMS membrane, and thus separated into a permeate stream passing into the micropores and microcapillary channels of the fiber or film and a retentate stream not passing through the micropores.

[0007] CMS membranes may also be sub-categorized based on selectivity. Particularly, CMS membranes may be classified as being normally selective or reverse-selective. Reverse-selective membranes may be desired to effect gas separations of larger molecules from smaller molecules. Selectivity may depend on the micropore size and adsorbate-adsorbent surface interaction.

[0008] However, one issue in carbon dioxide separation processes with reverse selective membranes is the size of the secondary gas molecule. Particularly, some molecules, such as hydrogen, are of such a small size that they can often pass through even if the membrane is designed be reverse-selective. Accordingly, methods of producing reverse-selective CMS membranes are desired that provide high reverse-selectivity to effect gas separation, particularly separations involving carbon dioxide and hydrogen or other relatively small gas molecules.

[0009] Further, selectivity alone may not be an adequate measure of a CMS membranes’ suitability for carbon dioxide separation processes. Particularly, a second bottleneck in carbon dioxide separation is permeance, which is an expression of the permeability of the membrane divided by the effective thickness of the membrane. As permeance decreases, the surface area of the individual fibers or films needed to separate a given flowrate of gas mixture proportionally increases. As the CMS membranes incorporating these fibers and / or films need to be housed in sealed units to contain the gas, fabrication and maintenance costs can escalate, damaging economic viability of the process. Further, if the CMS membranes and / or individual fibers and films are too closely stacked to counteract the escalation in size, increased frictional losses and chance of gas maldistribution through the CMS membrane may result in net losses to efficiency. This may be a significant problem in some cases where the feed gas, such as flue gas, to the membrane is at a low pressure, or is driven by a means such as a blower or vacuum pump.

[0010] Accordingly, methods of producing CCh-sclectivc CMS membranes are desired that have high reverse selectivity and permeance, while limiting frictional loss through the CMS membrane, such as laminate CMS membrane. Methods of manufacture are discussed herein that produce laminate CMS membranes with the aforementioned benefits. Particularly, formed laminate CMS membranes according to one or more embodiments herein are rendered CO2selective by pyrolysis and oxidation of a poly vinylidene chloride (PVDC) copolymer fdm, which may be arranged into a microcapillary laminate of the fdms, at specific temperature and time thresholds. Further, CMS membranes according to one or more embodiments herein are rendered stable CO2 selective performance towards carbon dioxide-nitrogen separations in particular by an additional annealing step between the pyrolysis and oxidation steps.

[0011] Thus, stable carbon structures with consistent pore sizing may be achieved to allow substantial carbon dioxide permeance while maintaining high carbon dioxide-nitrogen selectivity. This increased carbon dioxide permeance may then be leveraged by reducing the number of individual microcapillary film layers of laminate CMS membranes. The straight and uniform spacing between the microcapillary film layers helps keep the pressure drop low and avoid the flow mal-distribution. Both can reduce the size of modules incorporating the same and increasing economic viability to the process.

[0012] According to one embodiment, a method of manufacturing a laminate carbon molecular sieve (CMS) membrane may comprise forming a polyvinylidene chloride copolymer into two or more microcapillary films; arranging the two or more microcapillary films into a microcapillary laminate comprising two or more widthwise spacers interposed between each of the two or more microcapillary films; pretreating the two or more microcapillary films by heating at a first temperature of from 120 °C to 200 °C with air, inert gas, under vacuum, or combinations thereof; pyrolyzing the two or more micro capillary films at a second temperature of from 600 °C to 700 °C with inert gas or under vacuum, wherein the arranging step occurs before or after the pyrolyzing step; annealing the microcapillary laminate at a third temperature of from 900 °C to 1700 °C with inert gas or under vacuum; and either oxidizing the microcapillary laminate at a fourth temperature of from 300 °C to 400 °C with air to form the CMS membrane, or oxidizing the microcapillary laminate at a fifth temperature of from 700 °C to 900 °C with carbon dioxide to form the CMS membrane.

[0013] According to another embodiment, a carbon molecular sieve (CMS) membrane may comprise a microcapillary laminate of two or more microcapillary films and two or more widthwise spacers interposed between each of the two or more microcapillary films, wherein: the two or more microcapillary films comprise a poly vinylidene chloride (PVDC) copolymer; and the CMS membrane comprises a carbon dioxide permeance of from 1000 gas permeation units (GPU) to 6000 GPU.

[0014] Additional features and advantages of the embodiments described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described, including the detailed description and the claims which are provided infra.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings in which:

[0016] Figure (FIG.) 1 is an illustration of a laminate carbon molecular sieve (CMS) membrane, according to one or more embodiments herein;

[0017] FIG. 2 is another illustration of a laminate CMS membrane, according to one or more embodiments herein, wherein the laminate CMS membrane is in a partially exploded view to show the top surface of the widthwise spacers, as well as that the widthwise spacer may comprise two or more microcapillary films;

[0018] FIG. 3 is another illustration of a laminate CMS membrane, according to one or more embodiments herein, also illustrating one or more reinforcement panels;

[0019] FIG. 4A is an illustration of a gas separation module incorporating one or more of the laminate CMS membranes of FIGS. 1-3 attached to a collection cap, as discussed in embodiments herein;

[0020] FIG. 4B is another illustration of one or more of the gas separation modules of FIG. 4A arranged for placement into a vessel, as discussed in embodiments herein;

[0021] FIG. 4C is an illustration of the one or more gas separation modules of FIG. 4B, inserted into a vessel for separating a gas mixture, as discussed in embodiments herein;

[0022] FIG. 5A is an illustration of a laminate CMS membrane in a cylindrical form, according to one or more embodiments herein;

[0023] FIG. 5B is an illustration of the front view of the laminate CMS membrane of FIG. 5 A illustrating the two or more widthwise spacers, according to one or more embodiments herein;

[0024] FIG. 5C is a partial illustration of a front view of the laminate CMS membrane of FIGS. 5A-5B illustrating the two or more widthwise spacers, according to one or more embodiments herein;

[0025] FIG. 5D is a partial illustration of a side view of the laminate CMS membrane of FIG. 5A, illustrating the two or more widthwise spacers, according to one or more embodiments herein;

[0026] FIG. 5E is an illustration of a gas separation module for use with, for example, the laminate CMS membrane of FIG. 5 A;

[0027] FIG. 6A is an illustration of the carbon dioxide permeance performance of a laminate CMS membrane, according to one or more embodiments herein;

[0028] FIG. 6B is an illustration of the nitrogen permeance performance of a laminate CMS membrane, according to one or more embodiments herein;

[0029] FIG. 6C is an illustration of the carbon dioxide / nitrogen selectivity of a laminate CMS membrane, according to one or more embodiments herein;

[0030] FIG. 7A is a scanning electron microscope photograph of an edge of a laminate CMS membrane, according to one or more embodiments herein; and

[0031] FIG. 7B is another scanning electron microscope photograph of an edge of a laminate CMS membrane, according to one or more embodiments herein.DETAILED DESCRIPTION

[0032] Embodiments described herein generally relate to carbon molecular sieve (CMS) membranes, and in particular laminate CMS membranes formed from microcapillary laminates of individual microcapillary fdms, as well as methods of manufacturing and processes for utilizing the same.

[0033] The gas permeation properties of a membrane, such as the CMS membranes described in further detail herein, may be determined by gas permeation experiments. Two intrinsic properties have utility in evaluating separation performance of a membrane material: its "permeability," a measure of the membrane's intrinsic productivity; and its "selectivity," a measure of the membrane's separation efficiency. One typically determines "permeability" (Pz) in Barrer( 1 Barrer — 10~10cm2 s cmH) calculated as the flux (nz) divided by the partial pressure difference between the membrane upstream and downstream (Apz). and multiplied by the thickness of the membrane (1). In the embodiments herein, the thickness of the membrane may begenerally expressed as the wall thickness, (OD-ID)* / 2, of the microcapillary film (1): Pt=

[0034] Another term, "permeance," is defined herein as productivity of the CMS membrane or individual microcapillary film and is typically measured in Gas Permeation Units (GPU)( 1 GPU — 106cm2 s cmHg) determined by dividing permeability by effective membrane separation layer thickness:

[0035] Finally, "selectivity" is defined herein as the ratio of one gas's permeability through the membrane or permeance relative to the same property of another gas. It is measured as a unitless . ratio:

[0036] As previously stated, embodiments herein are directed to carbon molecular sieve (CMS) membranes, and in particular laminate CMS membranes formed from microcapillary laminates. Accordingly, as used herein, all descriptions of microcapillary laminates may also apply to laminate CMS membranes, as the microcapillary laminates are the precursor to the laminate CMS membranes.

[0037] Now referring to FIG. 1, the microcapillary laminate 100 or the laminate CMS membrane formed therefrom, as previously explained, is illustrated. As shown in FIG. 1, the microcapillary laminate 100 or the CMS membrane formed therefrom may comprise two or more microcapillary fdms 110 and two or more widthwise spacers 120. As illustrated in FIG. 1, the two or more microcapillary fdms 110 comprise a plurality of microcapillary channels 111 running along the length of each of the microcapillary fdms 110. Although not shown, it is contemplated that each of the two or more microcapillary fdms 110 comprise porous and permeable top and bottom surfaces 112 / 113 that may be fluidly connected to the plurality of microcapidary channels 111.

[0038] In embodiments, the two or more microcapillary fdms 110 may comprise a copolymer, such as, but not limited to, a polyvinylidene chloride (PVDC) copolymer. The copolymer may also comprise at least one of the following comonomers: a vinyl monomer, a vinyl chloride monomer, an acrylate monomer, a methacrylate monomer, a styrenic monomer, acrylonitrile, methacrylonitrile, itaconic acid, and pyrolyzed chlorotrifluoroethylene. In embodiments, the PVDC copolymer may comprise at least 60 wt.%, or alternatively at least 70 wt.%, vinylidene chloride, based on the total weight of the copolymer.

[0039] Still referring to FIG. 1A, and as previously stated, the microcapillary laminate 100 or the CMS membrane formed therefrom may comprise the one or more widthwise spacers 120. The one or more widthwise spacers 120 may comprise a metal, a composite, cloth, an epoxy resin, acopolymer, or combinations thereof. For example, the one or more widthwise spacers 120 may comprise the PVDC copolymer, which may be similar or identical in some or all aspects to the PVDC copolymer-based microcapillary fdms 110. In other words, the one or more widthwise spacers 120 may themselves be microcapillary fdms 110 having a plurality of microcapillary channels.

[0040] Still referring to FIG. 1, the two or more widthwise spacers 120 may be parallel with the widthwise face 140, the lengthwise face 150, or both, of the two or more microcapillary fdms 110. In embodiments, and as shown in FIG. 1, the two or more widthwise spacers 120 may be aligned with the widthwise face 140, the lengthwise face 150, or both, although aligning the two or more widthwise spacers 120 with the widthwise face 140 or the lengthwise face may not be required. Particularly, as shown in the left side of FIG. 1, the two or more widthwise spacers 120 may be offset from, i.e. proximal to, the widthwise face 140. The two or more widthwise spacers 120 may additionally or alternatively be offset from, i.e. proximal to, the lengthwise face 150 (not shown).

[0041] As explained in further detail below, offsetting the one or more widthwise spacers 120 from at least the widthwise face 140 may be of benefit when sealing an interface 115 between the one or more widthwise spacers 120 and the top surface 112 of the microcapillary fdms 110, the bottom surface 113 of the microcapillary fdms 110, or both. Particularly, without being limited by theory, when the one or more widthwise spacers 120 are offset from the widthwise face 140 it may reduce the risk of accidentally sealing the plurality of microcapillary channels 111 of the two or more microcapillary fdms 110 with a subsequently applied adhesive, as explained in further detail herein. However, in at least some embodiments, the plurality of microcapillary channels 111 may be intentionally sealed at one of the widthwise faces 140. Without being limited by theory, sealing the plurality of microcapillary channels 111 at one of the widthwise faces 140 may allow capillary flow to be directed to the opposite face, which may be of some benefit in achieving a ‘dead-flow pattern’ when attempting to isolate the permeate and retentate streams, as explained in further detail herein.

[0042] Alternatively, in the event the one or more widthwise spacers 120 are aligned with one or both of the widthwise faces 140, the concern of sealing the plurality of microcapillary channels 111 with the adhesive may be addressed by removing at least a portion of the microcapillary laminate proximate one or both of the widthwise faces 140 after application of the adhesive, thereby re-exposing the plurality of microcapillary channels 111.

[0043] Further, additionally aligning the one or more widthwise spacers 120 with the lengthwise face 150 may have additional benefits if the one or more widthwise spacers 120 are relatively impermeable in the direction of the plurality of microcapillary channels 111. Particularly, this configuration may allow the lengthwise face 150 to be isolated from the remainder of the microcapillary laminate 100 or the laminate CMS membrane formed therefrom, such as when a sealing element and / or horizontal divider is arranged around the one or more widthwise spacers 120 and the two or more microcapillary films 110, as explained in further detail herein.

[0044] Now referring to FIG. 2, illustrated is a partially exploded view of another microcapillary laminate 100 (for the purposes of illustrating a top surface of the two or more widthwise spacers 120) as well as that the two or more widthwise spacers may comprises microcapillary films, as explained in further detail below. As shown in FIG. 2, the two or more widthwise spacers 120 may comprise two or more of the microcapillary films 110 stacked vertically. In such an embodiment, it is contemplated that arranging the two or more microcapillary films 110 and the two or more widthwise spacers 120 into the microcapillary laminate 100 or the CMS membrane formed therefrom may have the advantage of forming a seal between the microcapillary films and the widthwise spacers. Particularly, it is contemplated that the PVDC copolymers of the widthwise spacers 120 and the PVDC copolymers of the microcapillary films 110 may bond and / or partially fuse together during the placement of the adhesive, or during pretreatment, pyrolysis, and annealing, as explained in further detail hereinbelow.

[0045] Furthermore, the addition of a solvent when using microcapillary films 110 as the two or more widthwise spacers 120 may operate to soften the PVDC copolymers making up the two or more microcapillary films 110 and the two or more widthwise spacers 120 and promote additional bonding and / or fusing, as explained in further detail hereinbelow. Particularly, the solvent may be added to an interface 115 between the two or more microcapillary films 110 and the two or more widthwise spacers 120. Alternatively or additionally, the solvent may be added to an interface 116 between individual microcapillary films 110 of the two or more widthwise spacers 120. The solvent may include, but may not be limited to, tetrahydrofuran or n-methyl pyrrolidone.

[0046] Alternatively, or additionally, the microcapillary laminate 100 or the laminate CMS membrane formed therefrom may further comprise an adhesive, as previously described. Theadhesives may include, but may not be limited to polyimide, polyvinylidene chloride, polyvinyl chloride, an acrylic, or combinations thereof. Similar to the solvent, the adhesive may be added to the interfaces 115 / 116 to seal the individual layers of the microcapillary laminate 100 or the CMS membrane formed therefrom.

[0047] Now referring to FIG. 3, illustrated is another microcapillary laminate 100, according to embodiments herein. As shown in FIG. 3, and in embodiments, at least one of the two or more widthwise spacers 120 may be offset from the widthwise faces 140. For example, and as illustrated in FIG. 3, one or more of the two or more widthwise spacers 120 may be interposed between the widthwise spacers 120 aligned with the widthwise faces 140, such that these interposed widthwise spacers may be regarded as intermediate widthwise spacers 121. In embodiments, the intermediate widthwise spacers 121 may be porous or permeable such that gas flow may continue relatively interrupted across the two or more microcapillary films 110, as explained in further detail below. Additionally or alternatively, the intermediate widthwise spacers 121 may be offset from the widthwise face 140, may comprise one or more internal gaps to enable flow across the length of the two or more microcapillary fdms 110, or both to enable gas flow across the two or more microcapillary fdms 110.

[0048] Still referring to FIG. 3, the microcapillary laminate 100 or the CMS membrane formed therefrom may further comprise one or more reinforcement panels 160 disposed on the top surface 112 of the microcapillary fdms 110, the bottom surface 113 of the microcapillary fdms 110, or both. The one or more reinforcement panels 160 may also be separated from directly contacting the two or more microcapillary fdms 110 by the two or more widthwise spacers 120. As previously stated, the two or more microcapillary fdms 110 of the microcapillary laminate 100 may be relatively rigid post formation into the laminate CMS membrane. However, without being limited by theory, the two or more microcapillary fdms 110 of the microcapillary laminate 100 or the CMS membrane formed therefrom may still be susceptible to shattering when exposed to bending forces. Accordingly, the one or more reinforcement panels 160 may be added to the microcapillary laminate 100 or the laminate CMS membrane formed therefrom to provide bend and / or shatter resistance. Additionally, so as not to significantly reduce the performance of the laminate CMS membrane in later operation, the one or more reinforcement panels 160 may be porous and / or permeable. The one or more reinforcement panels 160 may comprise metal, plastic, carbon fiber, paper, cloth, or combinations thereof.

[0049] As previously discussed, embodiments herein may also be directed to laminate CMS membranes, which may be any of the microcapillary laminates 100 previously discussed. As previously discussed, the CMS membranes may have a permeance, expressed as the permeability to flow a gas over the membrane layer thickness. However, the CMS membranes may have different permeances for different sized gases. As previously discussed, the ratio of these different permeances may be expressed as a selectivity for a given gas. For instance, the CMS membrane may selectively separate different gases from each other. As discussed in further detail below, this may allow the CMS membranes to act as a preferential separator of different sized gases. The CMS membranes herein may also be reverse-selective. In other words, they may preferentially reject a smaller gas molecule from the membrane while accepting (and passing through) a larger gas molecule.

[0050] In embodiments, in an at least a carbon dioxide and nitrogen environment, the CMS membranes herein may have a carbon dioxide permeance of at least 1000 GPU or of at least 2000 GPU, such as from 1000 GPU to 1500 GPU, from 1500 GPU to 2000 GPU, from 2000 GPU to 2500 GPU, from 2500 GPU to 3000 GPU, or any combination of the previous ranges or smaller range therein, such as from 1000 GPU to 6000 GPU. The CMS membranes herein may also have a nitrogen permeance of less than or equal 900 to 40 GPU, such as from 40 GPU to 30 GPU, from 30 GPU to 20 GPU, from 20 GPU to 10 GPU, from 10 GPU to 1 GPU, or any combination of the previous ranges or smaller range therein, such as from 1 GPU to 40 GPU.

[0051] The CMS membranes herein may also have a carbon dioxide / nitrogen mixed gas selectivity of greater than 10, such as from 10 to 20, from 20 to 30, from 30 to 50, from 100 to 120, from 120 to 140, from 140 to 160, from 160 to 180, from 180 to 200, or any combination of the previous ranges or smaller range therein, such as from 80 to 200 or 50 to 200 at ambient temperature. Without being limited by theory, the above selectivities may allow the CMS membrane to preferentially separate the heavier carbon dioxide gas molecules from the lighter nirogen molecules.

[0052] Without being limited by theory, permeance and selectivity may be dependent on temperature and pressure. Accordingly, the aforementioned permeances and selectivities may be understood to occur at ambient temperature (20 °C) and 350 kPa gauge pressure, and thus may also be understood to change with respect to different temperatures and / or pressure. Particularly, it is contemplated that CO2 permeance may be understood to increase if measured at temperaturesabove ambient, and decrease at temperatures below ambient. The CO2 / N2 selectivity may be understood to increase at lower temperature, and decrease at higher temperature.

[0053] It is contemplated that, based on the increased permeance and selectivity of the microcapillary fdms 110 and CMS membranes herein, laminate CMS membranes incorporating the same may be of tighter spacing than other membranes known in the art without impacting membrane performance.

[0054] Particularly, in embodiments herein, a spacing between each of the two or more microcapillary fdms 110 of the CMS membrane may be less than 1000 microns, such as from 200 microns to 300 microns, from 300 microns to 500 microns, from 500 microns to 700 microns, from 700 microns to 900 microns, from 900 microns to 1000 microns, or any combination of the prevous ranges or smaller range therein, such as from 200 microns to 1000 microns or from 200 microns to 300 microns. In other words, the two or more widthwise spacers 120, the intermediate widthwise spacers 121, or both may comprise a thickness of less than 1000 microns, such as from 200 microns to 300 microns, from 300 microns to 500 microns, from 500 microns to 700 microns, from 700 microns to 900 microns, from 900 microns to 1000 microns, or any combination of the previous ranges or smaller range therein, such as from 200 microns to 1000 microns or from 200 microns to 300 microns.

[0055] In embodiments, the two or more microcapillary fdms 110 may each have a thickness of from 100 microns to 1000 microns, such as from 200 microns to 300 microns, from 300 microns to 400 microns, from 400 microns to 500 microns, or any combination of the previous ranges or smaller range therein. Accordingly, laminate CMS membranes according to embodiments herein may have a fdm surface area density of from 200 to 4000 square meters (m2) microcapillary fdm per cubic meter (m3) of laminate CMS membrane, such as from 200 to 400, from 400 to 800, from 800 to 1200, from 1200 to 2000, from 2000 to 3000, or from 3000 to 4000 m2fdm per m3of laminate CMS membrane, or any combination of the previous ranges or smaller range therein, such as from 400 to 4000 m2fdm per m3of laminate CMS membrane or from 2000 to 4000 m2fdm per m3of laminate CMS membrane. Without being limited by theory, this increased fdm surface area density of the laminate CMS membrane may allow degrees of magnitude smaller vessels 210 over what was previously required to enable gas separation. Moreover, as the scaling of vessels 210 are often the major cost, the laminate CMS membranes herein are of considerable benefit in the field of membrane separation.

[0056] As previously stated, embodiments herein are also directed to methods of manufacturing a carbon molecular sieve (CMS) membrane. The method may initially comprise forming a copolymer into two or more microcapillary fdms 110, which may be any of the microcapillary fdms 110 previously discussed. The method may also comprise pretreating the two or more microcapillary fdms 110 by heating at a first temperature of from 120 °C to 200 °C with air, an inert gas, under vacuum, or combinations thereof. The method may also comprise pyro lyzing the two or more micro capillary fdms 110 at a second temperature of from 600 °C to 700 °C with inert gas or under vacuum. The method may also comprise arranging the two or more microcapillary fdms 110 into a microcapillary laminate 100 comprising two or more widthwise spacers 120 interposed between each of the two or more microcapillary fdms 110, which may occur before or after the pyrolyzing step. The method may further comprise annealing the two or more microcapillary fdms 110 at a third temperature of from 900 °C to 1500 °C with inert gas or under vacuum. The method may furthermore comprise oxidizing the two or more microcapillary fdms 110. The two or more microcapillary fdms 110 may be oxidized at a fourth temperature of from 300 °C to 400 °C, or at a fifth temperature of from 700 °C to 900 °C. The two or more microcapillary fdms 110 may be oxidized with air, carbon dioxide, or both. Additionally or alternatively, the two or more microcapillary fdms 110 may be oxidized with a carbon dioxideinert gas mixture.

[0057] As previously stated, methods may initially comprise forming the copolymer into a microcapillary film. The copolymer may include, but may not be limited to, a polyvinylidene chloride (PVDC) copolymer.

[0058] In embodiments, the copolymer may be formed through copolymerization of the copolymer with a comonomer, such as those comonomers previously described. Following the copolymerization, the copolymer may be formed into the two or more microcapillary fdms 110 by any suitable method known to those known in the art. For example, the microcapillary fdms 110 may be produced by biaxial stretching using known fdm processes for copolymers.

[0059] As previously stated, the method may further comprise arranging the two or more microcapillary fdms 110 into a microcapillary laminate 100, which may be any of the microcapillary laminates 100 previously discussed. However, as previously stated, the arranging step may occur before or after the pyrolyzing step. For example, and in embodiments, the copolymers may be arranged into the microcapillary laminate 100 or the graphitized copolymers may be arranged into the microcapillary laminate 100.

[0060] Without being limited by theory, arranging the two or more microcapillary films 110 into the microcapillary laminate 100 prior to pyro lyzing may have the advantage of the films being less susceptible to shattering when arranging into the laminate.

[0061] Alternatively, arranging the two or more microcapillary films 110 into the laminate after pyrolyzing may have the advantage of not needing to use any or as many intermediate widthwise spacers 121 in the microcapillary laminate 100, as the microcapillary film has a greater degree of stiffness post pyrolysis.

[0062] As previously stated, in at least some embodiments, the method may further comprise pretreating the two or more microcapillary films 110 by heating at a first temperature of from 120 °C to 200 °C with air, inert gas, under vacuum or combinations thereof. In embodiments, the pretreatment of the two or more microcapillary films 110 may be used to stabilize, or “lock,” the copolymer structure prior to pyrolysis / carbonization thereof, such as when the copolymer is the PVDC copolymer.

[0063] The first temperature may also be at any temperature range within 120 °C to 200 °C. For example, the two or more microcapillary films 110 may be heated at the first temperature of from 120 °C to 130 °C, from 130 °C to 150 °C, from 150 °C to 160 °C, from 160 °C to 180 °C, from 180 to 190 °C, from 190 to 200, or any combination of ranges or smaller range therein. In embodiments, heating at any of these temperatures may also crosslink an interior of the two or more microcapillary films 110.

[0064] Pretreating the two or more microcapillary films 110 may further comprise contacting the two or more microcapillary films 110 with air, inert gas, or both. Contacting the two or more microcapillary films 110 with air or inert gas may occur at a rate sufficient to purge the pretreatment gas products, such as methane, hydrogen, carbon monoxide, and carbon dioxide, thereby preventing secondary reactions of the pretreatment gas products on the carbon surface.

[0065] In at least those embodiments wherein the arranging step occurs before the pretreating step, the method may further comprise applying a solvent, an adhesive, or both to one or both of the interfaces 115 / 116, such as any of the solvents or adhesive previous described. Without being limited by theory, the application of the solvent and / or adhesive to the microcapillary laminate 100 may increase the degree of sealing between the two or more microcapillary films 110 and the two or more widthwise spacers 120. Additionally, the method may further comprise, prior to pretreating, applying a compressive force to the microcapillary laminate 100. Without being limited by theory, applying a compressive force to the microcapillary laminate 100 may operateto increase the degree of fusing and / or bonding between the layers in addition to or alternatively from (in the case of PVDC copolymer widthwise spacers 120) the solvent and adhesive.

[0066] Alternatively or additionally, prior to pretreating, the method may further comprise sandwiching the microcapillary laminate 100 between two graphite plates. Without being limited by theory, the use of the graphite plates may reduce the chance of the two or more microcapillary fdms 110 warping during the pretreating, pyro lyzing, annealing, and oxidation processes, and thus increase the degree of seal between the two or more microcapillary fdms 110 and the two or more widthwise spacers 120.

[0067] As previously stated, the method may further comprise pyrolyzing the two or more microcapillary fdms 110 at the second temperature of from 600 °C to 700 °C with inert gas or under vacuum. The second temperature may also be at any narrower temperature range within the 600 to 700 °C. For example, the two or more microcapillary fdms 110 may be pyrolyzed at the second temperature of from 600 °C to 625 °C, from 625 to 650 °C, from 650 °C to 675 °C, from 675 °C to 800 °C, or any combination of ranges or smaller range therein, such as from 625 °C to 675 °C. As previously stated, pyrolyzing the two or more microcapillary fdms 110 at the second temperature may further comprise contacting the two or more microcapillary fdms 110 with inert gas.

[0068] In embodiments, inert gas may comprise carbon dioxide, nitrogen, any noble gas (including but not limited to argon), or combinations thereof. Contacting the two or more microcapillary fdms 110 with inert gas may occur at a rate sufficient to purge away the pyrolysis gas products, thereby preventing secondary reactions of the pyrolysis gas products on the carbon surface.

[0069] As previously stated, the method may further comprise annealing the two or more microcapillary fdms 110 at the third temperature of from 900 °C to 1500 °C with inert gas or under vacuum. The third temperature may also be from 900 °C to 1000 °C, from 1000 °C to 1100 °C, from 1100 °C to 1200 °C, from 1200 °C to 1300 °C, from 1300 °C to 1400 °C, from 1400 °C to 1500, or combinations of the previous ranges or smaller ranges therein, such as from 1200 °C to 1500 °C.

[0070] As previously stated, the method may alternatively or additionally comprise oxidizing the two or more microcapillary fdms 110 at the fourth temperature of from 300 °C to 400 °C, such as with air. The fourth temperature may also be from 300 °C to 310 °C, from 310 °C to 350 °C,from 350 °C to 375 °C, from 375 °C to 400 °C, or any combination of ranges or smaller range therein.

[0071] As previously stated, the method may alternatively or additionally comprise oxidizing the two or more microcapillary fdms 110 at the fifth temperature of from 700 °C to 900 °C, such as with carbon dioxide. The fifth temperature may also be from 700 °C to 710 °C, from 710 °C to 750 °C, from 750 °C to 800 °C, from 800 °C to 850 °C, from 850 °C to 890 °C, from 890 °C to 900 °C, or any combination of ranges or smaller range therein.

[0072] In embodiments, in the oxidizing step, the two or more microcapillary films 110 may comprise substantially no oxygen molecules if the oxidation occurs at the fifth temperature. Without being limited by theory, the oxygen content of air may impact the rate of oxidation of the two or more microcapillary films 110. For instance, at greater oxygen contents, the oxidation rate of the two or more microcapillary films 110 may correspondingly increase. It is also known that steam and CO2 may be milder oxidants than air. Accordingly, without being limited by theory, a similar level of oxidation and pore opening may be achievable with steam and / or CO2 at higher temperatures than for air.

[0073] The CMS membranes formed according to methods herein may have an oxygen content of from 5 atom% (atomic ratio) to 17 atom%, such as from 5 atom% to 7 atom%, from 7 atom% to 9 atom%, from 9 atom% to 12 atom%, from 12 atom% to 16 atom%, from 16 atom% to 17 atom%, or any combination of ranges or smaller range therein.

[0074] With respect to the previous oxygen content ranges, it is contemplated that a certain degree of oxidation may be needed to reach a particular level of pore opening. Particularly, during oxidation with carbon dioxide, two reactions may be occurring: oxygenate formation on carbon surface and CO gas formation. Accordingly, the oxygen content of the CMS membranes may correlate with the extent of pore opening and / or the degree of oxidation. In embodiments, the CMS membrane may comprise an oxygen content of from 5 atom% to 17 atom%.

[0075] In embodiments wherein the two or more microcapillary fdms 110 are oxidized with carbon dioxide instead of oxygen, the two or more microcapillary fdms 110 post-oxidation (or the CMS membranes formed utilizing the same) may comprise a reduced Henry’s adsorption constant to water than equivalent microcapillary fdms 110 or CMS membranes formed utilizing oxygen molecules as an oxidant. For example, and in embodiments, the two or more microcapillary fdms 110 post-oxidation (or the CMS membranes formed utilizing the same) may comprise a Henry’sadsorption constant to water of from 0.25 to 2.5 grams H2O per 100 grams microcapillary film per kilopascal of pressure, assuming measurement at 35 °C and 30% relative humidity.

[0076] As previously stated, the method may comprise applying an adhesive and / or a solvent to the interfaces 115 of the microcapillary laminate 100, such as prior to pretreating currently with the arranging step. However, in at least some embodiments the adhesive and / or solvent may be applied to the microcapillary laminate 100 after any one of the pyro lyzing, annealing, or oxidizing steps, such as if the microcapillary laminate 100 is arranged between any two of the pyro lyzing, annealing, or oxidizing steps. Further, post-oxidation and arranging, the method may comprise applying an additional amount of adhesive to the microcapillary laminate 100, now the CMS membrane post pyrolysis, annealing, and oxidation. Without being limited by theory, the applying of the additional amount of adhesive may operate to fdl any remaining gaps in the interfaces 115.

[0077] As previously stated, the method may comprise applying an adhesive and / or a solvent to the interfaces 115 / 116 of the microcapillary laminate 100, such as prior to pretreating. However, in at least some embodiments the adhesive and / or solvent may be applied to the microcapillary laminate 100 after any one of the pyro lyzing, annealing, or oxidizing steps, such as if the microcapillary laminate 100 is arranged between any two of the pyrolyzing, annealing, or oxidizing steps (whereas if the microcapillary laminate 100 is arranged after the oxidizing step the laminate CMS membrane would be formed, i.e. the two or more microcapillary fdms would be two or more CMS membranes). Further, post-oxidation and arranging, the method may comprise applying an additional amount of adhesive to the microcapillary laminate 100, now the laminate CMS membrane. Without being limited by theory, the applying of the additional amount of adhesive may operate to fdl any remaining gaps in the interfaces 115 / 116.

[0078] Now referring to FIGS. 4A-4C, in some embodiments the laminate CMS membranes formed from the microcapillary laminate, may be formed into a gas separation module 200. Particularly, as shown in FIG. 4 A, the widthwise face 140 of one or more of the CMS membranes (also labeled 100) may be fluidly coupled to a collection cap 202 to gather gas collected in the microcapillary channels 111 (not shown due to size) of the two or more microcapillary fdms 110. In this configuration, the two or more widthwise spacers 120 (not shown due to size) may be configured to prevent gas flowing along the two or more microcapillary fdms 110 from entering the collection cap 202, such as by being sealed against the two or more microcapillary fdms 110. As previously stated, offsetting the two or more widthwise spacers 120 from the two or more microcapillary fdms 110 may have additional benefits in such a configuration, as an adhesive orsolvent may be applied at the interfaces 115 / 116 shown in FIGS. 1-3, without risking sealing of the microcapillary channels 111.

[0079] As shown in FIGS. 4B-4C, two or more of the gas separation modules 200 may be arranged and positioned in a vessel 210, the vessel 210 comprising an inlet port 212. The vessel 210 may further comprise an outlet port (not illustrated) positioned at the opposite side of the vessel 210 of the inlet port 212, such that a gas feed flows across the faces of the microcapillary fdms and absorbs into the micropores of the same. As also shown in FIG. 4C, the collection caps 202 of the two or more gas separation modules 200 may each in turn be fluidly coupled to a permeate header 206 by one or more collection cap outlets 204 for gathering the gas collected in the microcapillary channels 111 of the two or more microcapillary fdms 110. It is contemplated that the collection caps 202, the collection cap outlets 204, the permeate header 206, or combinations thereof may be positioned either inside or outside the vessel 210.

[0080] Although not shown, the lengthwise edge of the microcapillary laminate 100 opposite the collection caps 202 may be sealed, such as when the two or more widthwise spacers are aligned with the lengthwise edge 150. Without being limited by theory, this configuration may force gas entering the microcapillary channels 111 of the two or more microcapillary films 110 to travel towards the collection cap 202, for gathering in the permeate header 206. Further, while not illustrated it is contemplated that the vessel 210 may comprise a hanger or rack for suspending or holding the two or more gas separation modules 200.

[0081] Although not illustrated, it is also contemplated that the vessel may be configured to form a tight fit around the two or more gas separation modules 200, and thus the microcapillary laminates 100, such that feed gas is forced across the face of the two or more microcapillary films 120 of the gas separation modules 200. Additionally or alternatively, it is also contemplated that the tight fit may be accomplished through the use of a filler material, or flexible gasket surrounding the two or more gas separation modules.

[0082] As previously stated and as shown in FIGS. 4A-4C, the CMS membranes 100 herein may be arranged into gas separation modules 200 and positioned in vessels 210 to enable the separation of gas mixtures. It is contemplated that there may be a variety of methods and geometries of arranging the laminate CMS membranes 100, as well as gas separation modules 200 incorporating the same, to accomplish desired gas separations.

[0083] For example, in at least one variation, the laminate CMS membrane 100, and / or the microcapillary laminate the laminate CMS membrane 100 is formed from, may be arranged intothe laminate CMS membrane 100 illustrated in FIGS. 5A-5D. As shown in FIGS. 5A-5B, the two or more microcapillary films 110 and the two or more widthwise spacers 120 (not shown in FIG. 5 A) may be arranged radially around a central axis 101, such that the combination of the two or more microcapillary films 110 and the two or more widthwise spacers 120 may resemble a cylinder. In such an embodiment, the microcapillary laminate 100 may further comprise one or more reinforcement rings 170, which may be similar in some aspects to the reinforcement panel 160. For example, although not illustrated, the one or more reinforcement rings 170 may at least partially extend along the length of the microcapillary fdms 110, such that the one or more reinforcement rings 170 resemble cylinders. Moreover, in such an embodiment, similar to the reinforcement panel 160, the one or more reinforcement rings 170 may be porous and / or permeable.

[0084] Now referring to FIGS. 5B and FIG. 5C, illustrated are front views of the microcapillary laminate 100 of FIG. 5 A for the purpose of better illustrating the two or more widthwise spacers 120. FIG. 5D is a zoomed-in side view of the microcapillary laminate 100 of FIG. 5A for the same purpose. As shown in FIGS. 5B and 5C, the two or more widthwise spacers 120 may be wedges having an increasing thickness as a function of distance from the central axis 101. However, as shown in FIGS. 5B-5D, the two or more widthwise spacers 120 may further comprise one or more gaps 126 along the length of the microcapillary laminate 100 to enable gas flow past the two or more widthwise spacers 120. Alternatively or additionally, the two or more widthwise spacers 120 may be porous and permeable, similar to the intermediate widthwise spacers previously described.

[0085] Still referring to FIGS. 5A-5D, the microcapillary laminate 100 may further comprise a collection cover 171, which may be similar or identical is some aspects to the collection cap 202. In embodiments, the collection cover 171 may be disposed on one of the ends of the microcapillary laminate 100, and may be fluidly connected to the microcapillary channels 111 of the two or more microcapillary fdms 110. Without being limited by theory, the collection cover 171 may comprise one or more internal grooves (not illustrated) for receiving the two or more microcapillary fdms 110, which may be subsequently sealed by applying an adhesive to the collection cover 171 and the two or more microcapillary fdms 110.

[0086] Now referring to FIG. 5E, a gas separation module 200 is illustrated, within which the laminate CMS membrane 100, of FIGS. 5A-5D may be positioned. As shown in FIG. 5E, the gas separation module 200 may comprise a vessel 210, which may be cylindrical to match the microcapillary laminate 100 of FIGS. 5A-5D. As also shown in FIG. 5E, the vessel 210 maycomprise an inlet port 212, a permeate outlet 213, a retentate outlet port 214, and a removable cover 215. The inlet port 212 may be sized to receive a perforated tube 216, which may alternatively be integral with the vessel 210. As shown in FIG. 5E, the perforated tube 216 may comprise one or more perforations 217, which may be sized and / or spaced to distribute a gas feed evenly along the circumference and length of the vessel 210. As previously stated, the vessel 210 may comprise a removable cover 215. The removable cover 215 may be positioned opposite the inlet port 212, and may be removable from the vessel 210 utilizing paired threads to the vessel 210, although other means are contemplated, such as but not limited to magnetic means, close tolerance fits, or any other fastening means understood in the art. Accordingly, without being limited by theory, it is contemplated that the microcapillary laminate 100 of FIGS. 5A-5D may be inserted into the vessel 210 after removing the removable cover 215, such as by the microcapillary channel 111 exposed end of the microcapillary laminate 100.

[0087] Still referring to FIG. 5E, although not illustrated, it is contemplated that the vessel 210 may further comprise a collection cover 171, which may be similar or identical is some aspects to the collection cap 202. In embodiments, the collection cover 171 may be disposed proximal the inlet port 212, and around the central axis 101. It is also contemplated that the collection cover 171 may be fluidly connected to the microcapillary channels 111 of the two or more microcapillary fdms 110 and a permeate outlet 213. Further, the collection cover 171 may comprise one or more internal grooves for receiving the two or more microcapillary fdms 110, the two of which may be subsequently sealed by applying an adhesive to the collection cover 171 and the two or more microcapillary fdms 110. Accordingly, a permeate from the microcapidary channels 111 of the two or more microcapillary fdms 110 may be isolated and separated from a gas feed, as explained previously.

[0088] As stated above, embodiments herein are also directed to processes for separating gases from a gas mixture, such as, but not limited to, flue gas. The gas mixture may comprise first gas molecules and second gas molecules. The second gas molecules, such as hydrogen, nitrogen, methane, or combinations thereof, may have a lesser representative molecular diameter than the first gas molecules, which may include carbon dioxide. Generally, the process may comprise manufacturing a laminate CMS membrane, which may be any of the laminate CMS membranes, or any of the processes for manufacturing the same, previously stated. The method may also comprise flowing the gas mixture through the CMS membrane and separating the gas mixture to produce a permeate stream and a retentate stream. As previously stated, in at least someembodiments the flue gas may be provided to the laminate CMS membrane at low pressure. For example, and in embodiments, the flue gas may be at a pressure of from 0 to 20 psig.

[0089] In embodiments, the permeate first stream may have an increased concentration of the first gas molecules as compared to the second retentate stream, which in turn may have an increased concentration of the second gas molecules as compared to the permeate first stream. In this way, the CMS membrane used in the process may operate to separate the first gas molecules and the second gas molecules from each other, and may be reverse-selective.

[0090] As previously stated, determining the micropore / molecular sizing of the CMS membranes is important to determine the CMS membranes’ suitability for particular separations. Different ways to determine the molecular size have been developed. One commonly employed approach has been to determine a given molecule's "kinetic diameter." A reference listing a variety of these kinetic diameters, based upon their use in zeolite applications, is D.W. Breck, Zeolite Molecular Sieves: Structure, Chemistry and Use, John Wiley & Sons, Inc. (New York, N.Y. 1974), 636, and these determinations are frequently used even with respect to non-zeolite, carbon molecular sieves that are known to have slit- shaped pores. In view of the above and for purposes hereof, then, the following kinetic diameters, taken from the Breck reference cited supra, are used herein as the representative molecular diameters for the following molecules: He (2.6 Angstroms, A), H2(2.89 A), N2(3.64 A), CO2(3.3 A), CH4(3.8 A), C2H4(3.9 A), C3H8(4.3 A), i-C4Hio (5.0 A), SFe (sulfur hexafluoride) (5.5 A), and i-CsHis (iso-octane) (6.2 A). However, because that reference table lacks a kinetic diameter for ethane, and the kinetic diameter given therein for propylene is believed by at least some researchers to be inaccurate for CMS materials per se, the Lennard-Jones collision diameters are used herein, instead of the Breck kinetic diameters, for those two materials. These Lennard-Jones collision diameters are, respectively, C2He (4.1 A), and C3H6 (4.0 A). See, for example, Staudt-Bickel C., Koros W. J., "Olefin / paraffin gas separations with 61-DA-based polyimide membranes," J. Membr. Sci. (2000) 170 (2), 205-214 for further discussion. The kinetic diameters and Lennard-Jones collision diameters are referred to together as "representative molecular diameters."EXAMPLES

[0091] Microcapillary fdms and microcapillary laminates of the same were formed according to embodiments herein for permeation testing, as explained in further detail hereinbelow.

[0092] Microcapillary Film Preparation

[0093] Microcapillary films, according to embodiments herein, were extruded using PVDC resins obtained from SK Global SARAN, particularly SBR711, which is a PVDC copolymer resin containing approximately 8.5 wt.% methyl acrylate. In particular, the microcapillary film die had a simple split body design with a two-inch wide air manifold insert that contained 42 parallel hollow pins positioned near the exit of the die used to introduce air into the polymer melt forming microcapillaries. The extruder pumping rate and air flow rate were adjusted to achieve the desired microcapillary diameter.

[0094] A 0.75 -inch diameter single screw extruder with three-barrel temperature zones was used to extrude the PVDC microcapillary film samples. An elbow adaptor was fabricated to position the microcapillary film die such that the extruded tape will be directed down into a water bath. The elbow and die were heated using metal heating elements that were clamped in place. The temperatures of the three zones of the extruder, the elbow, and die were increased from 155 °C to 170 °C until no unmelt resin was seen in the extruded film. The temperatures were kept as low as possible to avoid the thermal decomposition of PVDC resin. Polyethylene (PE) resin was periodically fed into the extruder to flush out char build up periodically.

[0095] Upon extrusion from the die, the microcapillary film was quenched into a room temperature water bath where upon it was wrapped around a guide roll at the bottom of the bath and then pulled out of the bath by a winder. The film was stretched by increasing the speed of the winder. Stretching occurred near the exit of the die and reduced the film thickness as well as the film width. The extruded microcapillary films were then cut into approximately 3 -foot strips and laid out on the top of a flat lab bench in atmospheric conditions to fully crystallize the PVDC for approximately one week.

[0096] Microcapillary laminate Formation - Heat Lamination

[0097] To prove the heat lamination concept, microcapillary tapes of 7.62 cm length and 1.27 cm width were cut out of the melt extruded films for the microcapillary films. Additional tapes of 1.27 cm length and width were cut for the widthwise spacers. The two were then alternatively stacked to form the microcapillary laminate. The laminate was then exposed to a one kilogram compressive force and heated to approximately 120 °C in an air purged oven for approximately ten minutes.

[0098] Microcapillary laminate Formation - Graphite Plates

[0099] To prove the graphite plate concept, microcapillary tapes of 7.62 cm length and 1.27 cm width were cut out of the melt extruded films for the microcapillary films. PVDC woven clothsof about 1.27 cm length and width were used for the widthwise spacers. The PVDC woven cloths were themselves made up of plan- wo ven PVDC fibers. The two were then alternatively stacked to form the microcapillary laminate. The laminate was then sandwiched between graphite plates and heated to 130 °C in an air purged oven for approximately 24 hours.

[0100] Microcapillary laminate Formation - Adhesive Weld

[0101] To prove the adhesive weld concept, microcapillary tapes of 7.62 cm length and 1.27 cm width were cut out of the melt extruded films for the microcapillary films. Additional tapes of 1.27 cm length and width were cut for the widthwise spacers. The two were then alternatively stacked with adhesive between the layers to form the microcapillary laminate. The spacers and interface between the spacers and the microcapillary films were then coated with an additional layer of adhesive by using a casting knife. The laminate and adhesive were respectively pretreated and cured at approximately 80 °C for approximately 10 minutes.

[0102] Microcapillary laminate Formation - Solvent Weld

[0103] To prove the solvent weld concept, microcapillary tapes of 7.62 cm length and 1.27 cm width were cut out of the melt extruded films for the microcapillary films. Additional tapes of 1.27 cm length and width were cut for the widthwise spacers. The two were then alternatively stacked with one drop of tetrahydrofuran solvent applied between the layers to form the microcapillary laminate. The laminate was then exposed to an approximately one kilogram compressive force for approximately two minutes, before being left in an air hood overnight to evaporate the THF at room temperature.

[0104] Select laminates were then individually placed between two porous graphite plates. Two pieces of Whatman filter paper (Whatman 1003-125) were placed between the PVDC microcapillary film and the porous graphite plates (each ~ 100 grams) as a cushion. The laminate / filter paper / graphite plates sandwich was placed in an air purged (two Titer / min) oven for pretreatment. The temperature of the oven was raised to 130 °C at a ramp of 1 °C / min and then kept at 130 °C for 24 hours. The sandwich was taken out after the oven cooled down below 60 °C.

[0105] The pretreated laminates together with the filter paper and porous ceramic plate were then placed into a quartz tube furnace purged (two Titer / min) by nitrogen gas. The furnace was first raised to 250 °C at 0.1 °C / min, and then to a final pyrolysis temperature ranging from 600 to 900 °C at a 3 °C / min ramp and kept at the final temperature for two hours before cooled down. The samples were taken out after the furnace cooled down below 60 °C.

[0106] The pyrolyzed laminates were then placed into a porous graphite felt boat, which was subsequently loaded into a ceramic tube furnace (two inch diameter) purged (two Liter / min) by nitrogen gas for the annealing step. The furnace was first raised to the final temperature of 1000- 1700 °C at 5 °C / min, and then kept at the final temperature for 120 min before cooled down. The samples were taken out after the furnace cooled down below 60 °C.

[0107] A first copy of the laminates were then placed into a quartz tube furnace purged (0.3 T / min) by carbon dioxide for the oxidation step. A second copy of the laminates were introduced to a quartz tube furnace purged (0.3 T / min) by air. Each furnace was first raised to the final temperature at 3 °C / min ramp and kept at the final temperature for a specified time before being cooled down. The obtained laminates (now laminate CMS membranes) were kept in a nitrogen box unless otherwise specified before making into modules for permeation tests.

[0108] Permeation and Selectivity Testing

[0109] As previously stated, each of the laminate CMS membranes were then stored in nitrogen gas-rich containers until testing. Each of the laminate CMS membranes previously formed and discussed were then tested for gas permeation, as well as gas selectivity. This was accomplished by building custom made ring permeation cell “modules.” The ring cell has a five- inch outer diameter, a three inch inner diameter, four half-inch wide openings on the wall with 9 / 16 inch o-ring fitting and quarter-inch thick covers at two side with the o-ring seal. The o-rings were provided by SAE / MS. The lengthwise end of the laminate CMS membranes (or single layer microcapillary film) was inserted into one of the half-inch wide openings. A dam was then made using Gorilla All Purpose Putty Epoxy Stick, with Scotch Weld DP 100 epoxy used to fill the top of the Gorilla Putty Epoxy as well as seal the other end of the laminate CMS membrane.

[0110] Mixture gas permeation was tested using the modules. Mixed gases were first cleaned through an activated carbon guard bed, then fed into the reservoir inside the ring cell. The feed was a equimolar 52 psi gauge feed. The permeate side of the module was held at 1 psi gauge, with the retentate held at 0 psi gauge (atmospheric pressure). The permeance was calculated using the permeate flow rate, normalized by the cross-membrane pressure difference and the total membrane surface area. For microcapillary film, the membrane area is the product of un-sealed film length, width, and number of microcapillary films times two (each microcapillary film has two surfaces). The unit of permeance is GPU: 1 x10-6 cm3(S.T.P) / (s.cm2.cm Hg). The results of the permeation testing are shown below in the tables and paragraphs below. Each of the Exampleshereinbelow included spacers having a thickness of approximately 1000 microns where laminates were formed.

[0111] Examples 1-3 are for comparison, and include laminates formed without annealing or oxidation. Example 1 includes 10 mil (1 mil equals approximately 25.4 microns) microcapillary fdms or two layer laminates pyrolyzed at 550 °C and laminated using Gorilla Tough & Clear ™ double-sided tape as the spacer and adhesive, having a thickness of approximately 1000 microns. Example 2 includes 20-mil microcapillary fdms and two layer laminates pyrolyzed at 550 °C and laminated using 3M 5925 VEIB™ acrylic foam tape as the spacer and adhesive. Example 3 includes 20 mil 10-layer laminates pyrolyzed at 600 °C and laminated using Gorilla All Purpose Epoxy Stick putty adhesive as the spacer and adhesive. Separations using equimolar EI2 / CO2 / CEI4 and equimolar C3EI6 / C3EI8 were conducted. Single layer microcapillary fdms were formed for comparison for Examples 1 and 2.

[0112] Table 1: Non- Annealed & Non-Oxidized Permeation Performance

[0113] As shown in Table 1 above, the non-annealed non-oxidized laminates showed low carbon dioxide permeance (less than 100 GPU) in general. Rather, the membranes and laminates thereof showed more suitability for propylene / propane separations. Without being limited by theory, this shows that annealing and oxidizing, as well as the temperatures chosen therefor, have an appreciable impact on membrane performance. In all cases, the laminate showed similar and high separation selectivities, demonstrating that the seal is gas tight.

[0114] Example 4, in contrast to Examples 1-3, includes 10 mil single layer microcapillary laminates formed using pyrolysis at 600 °C, annealing at 1200 °C, and oxidation with carbon dioxide at 800 °C for 6 hours. The permeance and selectivity testing was conducted with an equimolar carbon dioxide and nitrogen mixture at 40 psig and 22 °C. The performance of Example 4 is shown in FIGS. 6A-6C, which shows respectively carbon dioxide permeance over time,nitrogen permeance over time, and carbon dioxide / nitrogen selectivity over time. As shown in FIGS. 6A-6B, the annealed and oxidized membrane shows stability, adequate carbon dioxide permeance, and selectivity.

[0115] Example 5 includes 20 mil (again, 1 mil is approximately 25.4 microns) membranes pyro lyzed at 600 °C, annealed at 1200 °C under inert gas, and oxidized at 800 °C for 6 hours using carbon dioxide. Example 6 includes membranes pyrolyzed at 600 °C, annealed at 1200 °C under inert gas, and oxidized at 350 °C for 8 hours using air. Both single layer membranes and three layer laminates were formed for Examples 5 and 6, with lamination accomplished using Gorilla All Purpose Epoxy Putty Stick as both the spacer and adhesive, having a thickness of approximately 1000 microns. The permeation results with 20 psig equimolar feed are shown below in Table 2. The feed column refers to whether the gas species were fed individually (with purge between tests) or together. For the temperature column, the temperature refers to the permeation test temperature. The membrane module was immersed in a chilled bath for temperature control.

[0116] Table 2: Examples 5 and 6 Permeation Performance

[0117] As shown above in Table 2, the carbon dioxide / nitrogen selectivity was observed to approximately double when the temperature of the laminate was reduced from 22 °C to 0 °C. While the three-layer module exhibited lower CO2 permeance and selectivity, it is contemplated that this reduced performance may be due to ‘concentration polarization.’ Particularly when thepermeate flow is very large, the bulk gas transport resistance to the laminate surface becomes not negligible. This issue is exacerbated by the used permeation module in-lab design, which allows most of the feed gas to go around the membrane stacks with least resistance, i.e., the feed gas may primarily bypass the approximately 7.62 cm by 1.27 laminate in the 7.62 inner diameter circular module. Accordingly, by theoretically forcing the feed gas only through the laminate, as in the figures herein, ‘concentration polarization’ may be minimized, with permeance and selectivity greatly improving. However, even with all the previous being said, some laminate still exhibited desired performance levels, see particular the 38.8 selectivity laminate in Example 5 and the 36.3 selectivity laminate in Example 6, which each also achieved greater than 1000 carbon dioxide permeance.

[0118] Examples 7 and 8 are two-layer laminates utilizing a microcapillary film as the widthwise spacer. In Examples 7 and 8, a thin layer of adhesive, ADCOTE 102A and AQUALAM 444A, respectively, was applied to either side of the widthwise spacer using a syringe to show the flexibility in the types of adhesives useable with the laminates. The laminates were then heat laminated in an oven at approximately 80 °C at about 50 psi gauge. The laminate was then pretreated at 130 °C and pyro lyzed at 550 °C.

[0119] FIGS. 7A-7B illustrate scanning electron microscope photographs of Examples 7 and 8, respectively, which indicate that a satisfactory seal was established between the widthwise spacer and the two microcapillary films due either to the bonding / fusing of the spacer and the microcapillary films or the remaining presence of the adhesive. Further, as shown in FIGS. 7A- 7B, the microcapillary channels of the individual microcapillary films remain intact, indicating that the laminate may be used in later gas separations. Moreover, in embodiments and as previously stated, the widthwise spacers may be offset from the widthwise face of the microcapillary film so as to allow the initial amount or additional amount of adhesive to be applied with risking blocking of the microcapillary channels.

[0120] As shown in FIGS. 7A-7B, illustrating Examples 7 and 8 respectively, the microcapillary channels of the widthwise spacer were located 90 degrees to the two primary microcapillary films, such that the only permeate through the two primary microcapillary films

[0121] Finally, Examples 9 and 10 are similar three and five-layer laminates utilizing microcapillary films as the widthwise spacers, wherein each widthwise spacer comprises multiple layers of microcapillary films, as shown in FIG. 2. Particularly, in Examples 9 and 10, like in FIG.2, each of the widthwise spacers comprises three microcapillary films arranged in a stack. A solvent, tetrahydrofuran, was also applied between each of the microcapillary films in the widthwise spacers and in the layers of the microcapillary laminate in general.

[0122] The Example 9 laminates were then pretreated at 130 °C and pyrolyzed at 600 °C. The Example 10 laminates were pretreated at 130 °C, pyrolyzed at 600 °C, annealed at 1200 °C, and oxidized in air at 275°C for 8 hours. The permeation results for Examples 9 and 10 are shown below in Table 3.

[0123] Table 3: Examples 9 and 10 Permeation Performance

[0124] As shown in Table 3 above, both examples 9 and 10 exhibited selectivities of a variety of gas mixtures, indicating that the solvent bonded satisfactorily and maintained a seal between the laminate layers.

[0125] According to a first aspect, a method of manufacturing a laminate carbon molecular sieve (CMS) membrane may comprise forming a polyvinylidene chloride copolymer into two or more microcapillary films; arranging the two or more microcapillary films into a microcapillary laminate comprising two or more widthwise spacers interposed between each of the two or more microcapillary films; pretreating the two or more microcapillary films by heating at a first temperature of from 120 °C to 200 °C with air, with inert gas, under vacuum, or combinations thereof; pyrolyzing the two or more microcapillary films at a second temperature of from 600 °C to 700 °C with inert gas or under vacuum, wherein the arranging step occurs before or after the pyrolyzing step; annealing the microcapillary laminate at a third temperature of from 900 °C to 1700 °C with inert gas or under vacuum; and either: oxidizing the microcapillary laminate at a fourth temperature of from 300 °C to 400 °C with air to form the CMS membrane, or oxidizing the microcapillary laminate at a fifth temperature of from 700 °C to 900 °C with carbon dioxide to form the CMS membrane.

[0126] A second aspect may comprise the first aspect, wherein arranging the two or more microcapillary films comprises providing a spacing between each of the two or more microcapillary films that is from 100 microns to 1000 microns.

[0127] A third aspect may comprise either the first or second aspects, wherein the two or more microcapillary films each have a thickness of from 200 microns to 500 microns; and the combination of the thickness and the spacing results in a microcapillary film surface area density of from 200 to 4000 square meters microcapillary film per cubic meter of CMS membrane.

[0128] A fourth aspect may comprise any of the previous aspects, wherein the two or more microcapillary films each have a thickness of from 200 microns to 500 microns; and the two or more widthwise spacers each have a thickness of from 200 microns to 500 microns.

[0129] A fifth aspect may comprise any of the previous aspects, and may further comprise applying a compressive force to the microcapillary laminate prior to pretreating the two or more microcapillary films.

[0130] A sixth aspect may comprise any of the previous aspects, wherein the two or more widthwise spacers comprise polyvinylidene chloride copolymer.

[0131] A seventh aspect may comprise any of the previous aspects, wherein the arranging step further comprises interposing one or more intermediate widthwise spacers between the two or more widthwise spacers; and the one or more intermediate widthwise spacers comprise a metal, a composite, cloth, an epoxy resin, a copolymer, or combinations thereof.

[0132] An eighth aspect may comprise any of the previous aspects, wherein the arranging step occurs prior to the pyrolyzing step; and the method further comprises sandwiching the microcapillary laminate between two graphite plates prior to pretreating the two or more microcapillary films.

[0133] A ninth aspect may comprise any of the previous aspects, wherein the arranging step further comprises applying an adhesive or a solvent to an interface between the two or more microcapillary films and the two or more widthwise spacers.

[0134] A tenth aspect may comprise any of the previous aspects, wherein the two or more microcapillary films and the two or more widthwise spacers are arranged radially around a central axis; and the two or more widthwise spacers comprise wedges, the wedges having an increasing thickness as a function of distance from the central axis.

[0135] An eleventh aspect may comprise any of the previous aspects, and may further comprise a process for separating a gas mixture comprising a first gas and a second gas utilizing the CMSmembrane, the process comprising: flowing the gas mixture through a CMS membrane manufactured according to any previous claim; and separating the gas mixture into a permeate first stream and a retentate stream, the permeate first stream comprising an increased concentration of the first gas and the retentate stream comprising an increased concentration of the second gas, wherein the second gas comprises a lesser representative molecular diameter than the first gas.

[0136] According to a twelfth aspect, a carbon molecular sieve (CMS) membrane may comprise a microcapillary laminate of two or more microcapillary films and two or more widthwise spacers interposed between each of the two or more microcapillary films, wherein: the two or more microcapillary films comprise a poly vinylidene chloride (PVDC) copolymer; and the CMS membrane comprises a carbon dioxide permeance of from 1000 gas permeation units (GPU) to 6000 GPU.

[0137] A thirteenth aspect may comprise the twelfth aspect, wherein the CMS membrane comprises a microcapillary film surface area density of from 200 to 4000 square meters microcapillary film per cubic meter of CMS membrane.

[0138] A fourteenth aspect may comprise either the twelfth or thirteenth aspects, wherein the two or more microcapillary films and the two or more widthwise spacers are arranged radially around a central axis; and the two or more widthwise spacers comprise wedges, the wedges having an increasing thickness as a function of distance from the central axis.

[0139] A fifteenth aspect may comprise any of the twelfth through fourteenth aspects, and may further comprise a process for separating a gas mixture comprising a first gas and a second gas utilizing the CMS membrane, the process comprising: flowing the gas mixture through the CMS membrane; and separating the gas mixture into a permeate first stream and a retentate stream, the permeate first stream comprising an increased concentration of the first gas and the retentate stream comprising an increased concentration of the second gas, wherein the second gas comprises a lesser representative molecular diameter than the first gas.

[0140] It is noted that recitations in the present disclosure of a component of the present disclosure being “operable” or “sufficient” in a particular way, to embody a particular property, or to function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references in the present disclosure to the manner in which a component is “operable” or “sufficient” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.

[0141] It is also noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc. The singular forms “a,” “an” and “the” include plural referents, unless the context clearly dictates otherwise.

[0142] Throughout this disclosure ranges are provided. It is envisioned that each discrete value encompassed by the ranges are also included. Additionally, the ranges which may be formed by each discrete value encompassed by the explicitly disclosed ranges are equally envisioned.

[0143] It is noted that terms like “preferably,” “commonly,” and “typically,” when utilized herein, are not utilized to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to identify particular aspects of an embodiment of the present disclosure or to emphasize alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure.

[0144] It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present invention, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.” It is noted that the use of the terms “having” or “including”, or grammatical variations thereof, in this disclosure should also be interpreted in like manner as the more commonly used open-ended preamble term “comprising”.

[0145] As used in this disclosure, terms such as “first” and “second” are arbitrarily assigned and are merely intended to differentiate between two or more instances or components. It is to be understood that the words “first” and “second” serve no other purpose and are not part of the name or description of the component, nor do they necessarily define a relative location, position, or order of the component. Furthermore, it is to be understood that the mere use of the term “first” and “second” does not require that there be any “third” component, although that possibility is contemplated under the scope of the present disclosure.

[0146] Having described the subject matter of the present embodiments herein in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Further, it will be apparent thatmodifications and variations are possible without departing from the scope of the present embodiments including, but not limited to, embodiments defined in the appended claims. More specifically, although some aspects of the present embodiments are identified herein as preferred or particularly advantageous, it is contemplated that the present embodiments is not necessarily limited to these aspects.

Claims

CLAIMS1. A method of manufacturing a laminate carbon molecular sieve (CMS) membrane, the method comprising: forming a polyvinylidene chloride copolymer into two or more microcapillary fdms; arranging the two or more microcapillary fdms into a microcapillary laminate comprising two or more widthwise spacers interposed between each of the two or more microcapillary fdms; pretreating the two or more microcapillary fdms by heating at a first temperature of from 120 °C to 200 °C with air, with inert gas, under vacuum, or combinations thereof; pyrolyzing the two or more microcapillary fdms at a second temperature of from 600 °C to 700 °C with inert gas or under vacuum, wherein the arranging step occurs either before or after the pyrolyzing step; annealing the microcapillary laminate at a third temperature of from 900 °C to 1700 °C with inert gas or under vacuum; and either: oxidizing the microcapillary laminate at a fourth temperature of from 300 °C to 400 °C with air to form the CMS membrane, or oxidizing the microcapillary laminate at a fifth temperature of from 700 °C to 900 °C with carbon dioxide to form the CMS membrane.

2. The method of claim 1, wherein arranging the two or more microcapillary fdms comprises providing a spacing between each of the two or more microcapillary fdms that is from 100 microns to 1000 microns.

3. The method of claim 2, wherein: the two or more microcapillary fdms each have a thickness of from 200 microns to 500 microns; and the combination of the thickness and the spacing results in a microcapillary film surface area density of from 200 to 4000 square meters microcapillary film per cubic meter of CMS membrane.

4. The method of any previous claim, wherein:the two or more microcapillary films each have a thickness of from 200 microns to 500 microns; and the two or more widthwise spacers each have a thickness of from 200 microns to 500 microns.

5. The method of any previous claim, further comprising applying a compressive force to the microcapillary laminate prior to pretreating the two or more microcapillary films.

6. The method of any previous claim, wherein the two or more widthwise spacers comprise polyvinylidene chloride copolymer.

7. The method of any previous claim, wherein: the arranging step further comprises interposing one or more intermediate widthwise spacers between the two or more widthwise spacers; and the one or more intermediate widthwise spacers comprise a metal, a composite, cloth, an epoxy resin, a copolymer, or combinations thereof.

8. The method of any previous claim, wherein: the arranging step occurs prior to the pyrolyzing step; and the method further comprises sandwiching the microcapillary laminate between two graphite plates prior to pretreating the two or more microcapillary films.

9. The method of any previous claim, wherein the arranging step further comprises applying an adhesive or a solvent to an interface between the two or more microcapillary films and the two or more widthwise spacers.

10. The method of any previous claim, wherein: the two or more microcapillary films and the two or more widthwise spacers are arranged radially around a central axis; and the two or more widthwise spacers comprise wedges, the wedges having an increasing thickness as a function of distance from the central axis.

11. A process for separating a gas mixture comprising a first gas and a second gas utilizing the CMS membrane manufactured according to any of claims 1-10, the process comprising: flowing the gas mixture through the CMS membrane; and separating the gas mixture into a permeate first stream and a retentate stream, the permeate first stream comprising an increased concentration of the first gas and the retentate stream comprising an increased concentration of the second gas, wherein the second gas comprises a lesser representative molecular diameter than the first gas.

12. A carbon molecular sieve (CMS) membrane, the membrane comprising a microcapillary laminate of two or more microcapillary films and two or more widthwise spacers interposed between each of the two or more microcapillary films, wherein: the two or more microcapillary films comprise a polyvinylidene chloride (PVDC) copolymer; and the CMS membrane comprises a carbon dioxide permeance of from 1000 gas permeation units (GPU) to 6000 GPU.

13. The membrane of claim 12, wherein the CMS membrane comprises a microcapillary film surface area density of from 200 to 4000 square meters microcapillary film per cubic meter of CMS membrane.

14. The membrane of either claim 12 or 13, wherein: the two or more microcapillary films and the two or more widthwise spacers are arranged radially around a central axis; and the two or more widthwise spacers comprise wedges, the wedges having an increasing thickness as a function of distance from the central axis.

15. A process for separating a gas mixture comprising a first gas and a second gas utilizing the CMS membrane of any of claims 12-14, the process comprising: flowing the gas mixture through the CMS membrane; and separating the gas mixture into a permeate first stream and a retentate stream, the permeate first stream comprising an increased concentration of the first gas and the retentate streamcomprising an increased concentration of the second gas, wherein the second gas comprises a lesser representative molecular diameter than the first gas.

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