Mixed matrix membranes, compositions and methods

Abstract

The present invention relates to a composition comprising: at least one porous solid additive having an electrically charged surface; - Charged surface agent; -polymerizable ionic liquid monomers; Here, the charged field agent is an ionic liquid (IL)-based oligomer containing three or more repeat units. The present invention also relates to mixed matrix membranes formed from the compositions and methods for making the mixed matrix membranes.

Description

Technical Field

[0001] The present invention relates to the field of gas separation using membranes. In particular, the present invention relates to the field of mixed matrix membranes. The present invention provides new membranes and methods for improving gas separation.

Background Art

[0002] The global demand for natural gas is increasing, and the demand for technologies that can improve extracted gas to pipeline grade is also growing. In 2019, 846.6 billion cubic meters of natural gas were consumed in the United States alone, that is, an increase of 3.3% in 2019 and an increase of 37% since 2009. The United States is the world's largest consumer, accounting for 21.5% of the world's consumption, far exceeding Russia (11.3%) and China (7.8%) (BP Statistical Review of World Energy 2020 - 69th edition and Statistical Review of world energy - June 2020).

[0003] Natural gas is mainly composed of methane (CH4), but may contain heavier hydrocarbons, water (H2O), carbon dioxide (CO2), hydrogen sulfide (H2S), helium (He), and nitrogen (N2). CO2 reduces the calorific value of natural gas and, in the presence of water, forms carbonic acid, which corrodes pipeline equipment, thus having an adverse effect on the quality of natural gas.

[0004] Common methods for removing CO2 include cryogenic distillation, pressure or temperature swing adsorption, amine washing, and membrane separation. Currently, amine washing is the mainstream technology, but membranes only account for a mere 5% of the separation market. However, washing requires a large amount of energy cost to remove CO2 from amine salts and poses an environmental risk.

[0005] Compared with energy-intensive CO2 separation methods such as amine washing and adsorption processes, membrane-based separation is generally considered to be environmentally friendly, require less floor space, and have lower capital and operating costs. A promising type of membrane material for CO2 / CH4 separation is mixed-matrix membranes (MMMs) that contain porous solids (such as zeolites) in a polymer matrix.

[0006] Research on membrane gas separation, especially MMMs, has focused on the development of membranes with high permeability and selectivity. Conventional MMMs are prepared by adding porous inorganic fillers to a polymer matrix. In fact, MMMs were proposed as a strategy to make more processable materials by taking advantage of the excellent separation properties of zeolites. For example, the preparation of MMMs can consist of incorporating zeolites into a rubbery polymer of poly(dimethylsiloxane).

[0007] However, it was soon found that the performance of MMMs is limited by the lack of interfacial adhesion between zeolite particles and the polymer matrix. The resulting interfacial voids are non-selective and provide low-resistance routes for gas transport, severely limiting the CO2 / CH4 separation ability of the first MMMs. One possible solution to limit this effect is to produce MMMs with a high zeolite loading. These MMMs showed a significant improvement in selectivity. However, high zeolite content leads to a decrease in mechanical stability and the formation of brittle MMMs, which are not suitable for the high pressure differentials present in natural gas separation processes.

[0008] The new MMMs are produced by in-situ radical crosslinking of a mixture consisting of a polymerized ionic liquid (PIL), a free ionic liquid (IL), and zeolite.

[0009] Ionic liquids (ILs) are organic molten salts with melting points below 100 °C, preferably at room temperature. ILs exhibit many properties different from other liquids, such as negligible vapor pressure, high thermal stability, and high solubility in a wide range of inorganic and organic compounds. Polymerized ionic liquids (PILs) are polymers with charged repeating units based on ILs (e.g., made from IL monomers). Since PILs are usually solid materials, the diffusion rates of ions and gases are lower than those of ILs, but the gas solubility values are comparable, and the mechanical stability is excellent.

[0010] Such MMMs have shown excellent performance in separating CO2 from CH4 in low-pressure single-gas tests (Bara et al. 2008. Improving CO2 permeability in polymerized room-temperature ionic liquid gas separation membranes through the formation of a solid composite with a room-temperature ionic liquid. Polym. Adv. Technol. 2008; 19: 1415-1420). In particular, the use of ILs has been shown to enhance the permeability of the membrane and promote the interaction between PIL (polymer) and zeolite (Hudiono et al. 2010. A three-component mixed-matrix membrane with enhanced CO2 separation properties based on zeolites and ionic liquid materials. Journal of Membrane Science 350 (2010) 117-123). Advantageously, the preparation of these MMMs involves radical polymerization by crosslinking, which is the most convenient for industrial production and can accommodate a wide variety of functional groups and chain lengths compared to condensation polymerization, cationic polymerization, and anionic polymerization.

[0011] Further research has shown that the presence of IL in the polymer matrix plasticizes the PIL. Thus, the addition of IL to the polymer matrix increased the permeability of the studied composite membranes. The IL disrupts the packing between the chains and the PIL matrix becomes more rubbery. Thus, the polymer chains can move more freely and the interfacial interaction with the surface of the zeolite particles is improved. This study shows that the presence of IL in the three-component MMM strengthens the adhesive interaction between the polymer matrix and the zeolite surface and improves the gas separation performance of the membrane (Hudiono et al. 2011. Novel mixed matrix membranes based on polymerizable room-temperature ionic liquids and SAPO-34 particles to improve CO2 separation. J. Membr. Sci. 370 (2011) 141-148).

[0012] Furthermore, it has been proposed to optimize the fundamental factors involved in the reduction of interfacial voids and the improvement of CO2 / CH4 separation performance of PIL-IL-zeolite MMMs (Singh et al. 2016. Determination and optimization of factors affecting CO2 / CH4 separation performance in poly(ionic liquid)- ionic liquid- zeolite mixed-matrix membranes. Journal of Membrane Science 509 (2016) 149-155). To control the interfaces between the three components of these MMMs, the zeolite loading, zeolite type, PIL structure, and amount of polymer crosslinking were varied. The effects of these variations on the CO2 / CH4 separation performance were studied, and optimized MMM materials with improved CO2 / CH4 selectivity and permeability were identified. Furthermore, the mechanical stability of these MMMs has been demonstrated, and these MMMs have recently been processed with an active layer of 100 nm thickness based on the PIL-IL platform. The combination of high CO2 / CH4 separation performance, mechanical stability, and potential processability represents a significant advance in materials for natural gas separation, and these MMMs are attractive candidates for future industrial applications of CO2 / CH4 separation.

Summary of the Invention

Problems to be Solved by the Invention

[0013] However, when these MMMs were tested under mixed gas, high pressure, and / or high temperature conditions, the CO2 / CH4 selectivity decreased dramatically. Furthermore, when these MMMs were applied as thin films, the permeability decreased significantly. In particular, the low CO2 / CH4 selectivity values observed under high pressure and high temperature gas test conditions may be due to the detachment of the PIL matrix from the selective zeolite particles and the formation of fine gas defects around them. Furthermore, as the operating temperature increases, the adsorption of CO2 on the surface of the zeolite particles is hindered, and the selectivity of these membranes at high temperatures further decreases. Little research has been published on reducing the selectivity loss of MMMs under mixed gas supply conditions.

[0014] Therefore, there is a need for a new method and an optimized composition mixture to produce MMMs with better CO2 / CH4 separation selectivity and CO2 permeability, using a low-cost system and enhancing stability over a long period when used under mixed gas, high pressure, and / or high temperature operating conditions.

[0015] The present invention aims to overcome the drawbacks of the prior art. One of the objectives of the present invention is to optimize the composition of these (PIL-IL-zeolite) mixtures and develop a method for producing MMMs with better CO2 / CH4 separation selectivity and CO2 permeability when used under mixed gas, high pressure, and / or high temperature operating conditions, and MMMs in which the phenomena of plasticization and swelling are less likely to occur.

[0016] In particular, the present invention proposes a new composition containing at least three components, which enables the production of MMMs with better selectivity and permeability under specific conditions such as mixed gas, high temperature, and high pressure. The new composition also enables the avoidance of local free IL defects. The present disclosure also proposes a new MMM and a method for manufacturing the same.

Means for Solving the Problems

[0017] The following presents a simplified summary of selected aspects, embodiments, and examples of the present invention for the purpose of providing a basic understanding thereof. However, this summary does not constitute an extensive overview of all aspects, embodiments, and examples of the present invention. The sole purpose of the summary is to present selected aspects, embodiments, and examples of the present invention in a concise form as an introduction to the more detailed description of the aspects, embodiments, and examples of the present invention that follow.

[0018] The inventors have developed improvements in the field of MMMs by using a charged surfactant formed by an IL-based oligomer containing three or more repeating units in a specific MMM composition.

[0019] Accordingly, in one aspect of the present invention, a composition is provided that includes: - at least one porous solid additive having a charged surface; - a charged surfactant; - a polymerizable ionic liquid, preferably a polymerizable ionic liquid monomer; wherein the charged surfactant is an ionic liquid (IL)-based oligomer containing three or more repeating units. This composition is preferably dedicated to MMM production.

[0020] By replacing conventional small molecule ILs with these IL oligomers, the viscosity of the "interface" component increases. These oligomers in the polymer enable the creation of a "grafted polymer network" with higher resistance to plasticization and swelling. Thus, it is possible to produce MMMs with improved CO2 / CH4 separation selectivity and CO2 permeability, especially when these MMMs are used under operating conditions of mixed gas, high pressure, and / or high temperature. Furthermore, and very advantageously, such compositions reduce system costs and enable them to be more stable (last longer) over time.

[0021] According to any other features of the composition, the composition may optionally include one or more of the following features alone or in combination: The ionic liquid-based oligomers are based on polymerized norbornene, oxanorbornene, styrene and / or acrylate moieties. Preferably, the IL-based oligomers are based on polymerized styrene and / or acrylate moieties. the at least one porous solid additive is selected from zeolites, metal peroxides, zeolitic imidazolate frameworks and metal-organic frameworks; Crosslinking agents are also included, in particular crosslinking agents used during the polymerization of polymerizable ionic liquids. -The charged field agent is Tf2N - , BF4 - , N(CN)2 - , PF6 - , C(CN)3 - , B(CN)4 - , N(SO2F)2 - , TfO - , SbF6 - , halide, and sulfonate. the at least one porous solid additive is selected from zeolites, metal peroxides, zeolitic imidazolate frameworks and metal-organic frameworks; The at least one porous solid additive is selected from: · Zeolites: Zeolite A, ZSM-5, Zeolite-13X, Zeolite-KY, Silicalite-1, SSZ-13, SAPO-34; MCM-41, MCM-48, SBA-11, SBA-12, SBA-15, mesoporous ZSM-5, activated carbon, TiO2, MgO; and / or ·MIL-96, MIL-100, MOF-5, MOF-177, ZIF-7, ZIF-8, Cu-TPA, Cu3(BTC)2, Cu-BPY-HFS. -Further comprising a crosslinker. The polymerizable ionic liquid comprises less than three repeat units.

[0022] According to another aspect of the present invention, there is provided a mixed matrix membrane formed from the composition of the present invention. In particular, the present invention relates to a mixed matrix membrane comprising: - At least one porous solid additive having a charged surface; - A charged surfactant; and - A polymerizable ionic liquid; wherein the charged surfactant is an ionic liquid-based oligomer containing three or more repeating units.

[0023] Preferably, the ionic liquid-based oligomer contains 20 or fewer repeating units, more preferably 10 or fewer repeating units.

[0024] According to another aspect, the present invention relates to the use of the mixed matrix membrane according to the present invention for gas separation, preferably CO2 separation.

[0025] According to any other feature of the composition, the composition may optionally contain one or more of the following features alone or in combination: - The use of the mixed matrix membrane for CO2 separation in a mixed gas is carried out at a pressure exceeding 40 bar, preferably exceeding 50 bar. - The use of the mixed matrix membrane for CO2 separation in a mixed gas is carried out at a temperature exceeding 50 °C, preferably exceeding 60 °C. - The use of the mixed matrix membrane for CO2 separation in a mixed gas is carried out at a pressure exceeding 50 bar and a temperature exceeding 60 °C.

[0026] According to another aspect of the present invention, there is provided a method for producing a mixed matrix membrane including the following steps. - A living chain-growth polymerization step based on a polymerizable ionic liquid containing less than three repeating units; - And a step of coating a solid porous additive having a charged surface with a charged surfactant, wherein the charged surfactant is an IL-based oligomer containing three or more repeating units.

[0027] According to any other optional feature of this method, the method can optionally include one or more of the following features alone or in combination. - including the step of controlling living chain-growth polymerization. - including a ring-opening metathesis polymerization (ROMP) step, or a controlled radical polymerization (e.g., ATRP or RAFT) step. - including the step of synthesizing an IL oligomer of a controlled length. - including the formation of an ultrathin layer.

[0028] According to another aspect, the present invention relates to a separation system including a mixed matrix membrane according to the present invention, formed from a composition according to the present invention, including any preferred or any embodiment.

[0029] The foregoing and other objects, features, and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0031] Exemplary embodiments of the present invention will be described below.

[0032] In the following description, "polymer" means either a (statistical, gradient, block, alternating) copolymer or a homopolymer.

[0033] "Copolymer" means a polymer containing several different or identical monomer units.

[0034] The term "oligomer" and similar terms such as dimer, trimer, or higher oligomers refer to oligomerization products containing 2, 3, or more units derived from monomers. The units may be the same or different.

[0035] The term "monomer" as used refers to a molecule that can undergo polymerization.

[0036] The term "polymerization" refers to a chemical method of converting monomers or a mixture of monomers into a polymer of a predefined structure (block, gradient, statistical, etc.), a chemical reaction in which two or more molecules combine to form a large molecule containing repeating structural units.

[0037] The expression "controlled polymerization" means a polymerization reaction that can be stopped.

[0038] The expression "chain-growth polymerization technique" means a polymerization that does not produce by-products and is distinguished from condensation polymerization.

[0039] The expression "ring-opening metathesis polymerization" (ROMP) is a type of olefin metathesis reaction. In this reaction, strained cyclic olefins are used to produce monodisperse polymers and copolymers with predictable chain lengths.

[0040] As used herein, the expression "ionic liquid" (i.e., "IL") refers to a molten salt at room temperature that consists of a cation and an anion and is liquid at 25°C. The IL according to the present invention can be produced by melting a salt, and when produced in this way, it consists only of ions. The IL can be formed from a homogeneous substance containing one type of cation and one type of anion, or can be composed of two or more types of cations and / or two or more types of anions. Thus, the IL can be composed of two or more types of cations and one type of anion. The IL can further be composed of one type of cation and one or more types of anions. Furthermore, the IL can be composed of a plurality of types of cations and a plurality of types of anions. The IL is most widely known as a solvent. The IL refers to small molecules such as single molecules or single units. Preferably, the IL is liquid at room temperature or above room temperature. The IL may also be a non-polymerizable room temperature IL.

[0041] The expression "polymerizable ionic liquid" (i.e., "polymerizable IL" or "IL monomer") refers to a polymerizable monomer or oligomer, preferably a monomer, at room temperature, preferably by radical polymerization. Such a polymerizable IL refers to an IL in which a cation or an anion has a polymerizable group.

[0042] The term "charged" refers to a molecule or mineral that has positive and / or negative charges at different positions within the molecule or mineral.

[0043] The term "moiety" refers to a specific segment or functional group of a molecule. A chemical moiety is often recognized as a chemical entity embedded in or attached to a molecule.

[0044] As used herein, the term "unsaturated" means that a moiety or molecule has one or more unsaturated units.

[0045] As used herein, the term "saturated" means that a moiety or molecule does not have one or more unsaturated units.

[0046] The term "skeleton" refers to the main chain of the polymers, copolymers, or oligomers of the present invention.

[0047] The term "separation" (separation membrane) means that specific molecules or ions in a mixture or non-mixture selectively pass between two media separated (by the membrane). The part of the mixture retained by the membrane is called the retentate (or concentrate), and the part passing through the latter is called the permeate. Separation is carried out under the action of a driving force for movement according to a defined separation mechanism. The properties of the membrane are determined by two parameters: permeability and selectivity.

[0048] The term "selectivity" refers to the characteristic of the specificity with which the permeate is retained by the membrane. In the context of this application, the selective permeability of the membrane means that the membrane can control the ingress and egress of molecules or ions between two media separated by the membrane.

[0049] The term "permeability" is a property of the membrane that enables molecules and ions to penetrate, cross, or move through the membrane, and is the ability of a fluid to pass through itself.

[0050] The term "mixed gas" refers to a mixture of at least two gases.

[0051] The term "high pressure" refers to a pressure of 40 bar or more, preferably 50 bar or more.

[0052] The term "high temperature" refers to a temperature of 50 °C or more, preferably 60 °C or more.

[0053] The term "high viscosity" refers to a viscosity of 5×10 -3 Pa·s, preferably 1×10 -2 Pa·s, more preferably 5×10 -2 Pa·s or more, measured at 25 °C and 1 atmosphere, for example by a viscometer.

[0054] The term "zeolite" can refer to either natural, synthetic or hydrated silicates or aluminosilicates, which are formed from a crystal structure mainly containing silicon, aluminum, oxygen, and ultimately phosphorus, and metals including titanium, tin, and zinc.

[0055] The term "porous" can refer to a material having pore spaces that are small gaps or openings allowing the passage of molecules. Porous materials, especially porous solids, can be mesoporous or microporous. According to IUPAC (International Union of Pure and Applied Chemistry), microporosity corresponds to pores with a size less than 2 nm (zeolite or aluminophosphate type), and mesoporosity (silica, alumina, carbon, metal oxides) corresponds to pores with a size of 2 - 50 nm. The size corresponds to the diameter.

[0056] The term "plasticization" generally refers to the softening or swelling of a polymer matrix by a permeating gas, which is considered to be caused by the swelling stress on the polymer network. It is well known that the sorption of carbon dioxide into a glassy polymer can reduce the selective permeability and promote local segmental organization, which may have a significant impact on the morphological performance of the membrane. Therefore, plasticization is the most frequently encountered phenomenon in polymer - gas systems for commercial CO2 / CH4 separation applications where the membrane is exposed to high concentrations of CO2 in the feed stream.

[0057] The expression "thin - film composite membrane" refers to the membrane thickness itself. The thickness of the membrane is preferably thinner than that of current mixed - matrix membranes. For example, the thickness of the mixed - matrix membrane is included in the range of 0.05 μm to 50 μm, preferably less than 5 μm, more preferably less than 2 μm.

[0058] When introducing elements of various embodiments of the present disclosure, the articles "a", "an", and "the" are intended to mean that one or more elements are present. The terms "comprising", "including", and "having" are intended to be inclusive and mean that additional elements other than the recited elements may exist.

[0059] Furthermore, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be construed as precluding the existence of additional embodiments that also incorporate the recited features.

[0060] As described above, current MMMs experience a decrease in CO2 / CH4 separation selectivity and CO2 permeability when used under operating conditions of mixed gas, high pressure, and / or high temperature. Furthermore, current MMMs have free ILs, which tend to further "pool" or aggregate in the center of the MMM film cross-section during casting, forming an extremely thin "dry" upper "crust" and / or bottom surface adjacent to the support film. Such "IL-defect" regions are significantly rate-limiting with respect to overall gas permeation through the thickness of the TFC MMM. Additionally, small molecule IL materials are not static in the polymer matrix and can undergo physical displacement under high pressure. This results in regions of low IL content near the feed-side membrane surface, where gas permeation is significantly slowed.

[0061] Furthermore, under high pressure and high temperature gas test conditions, plasticization and swelling of the organic polymeric IL and free IL (i.e., PIL + IL) matrix around the zeolite particles occur. This causes the PIL (polymeric IL) matrix to peel away from the selective zeolite particles, forming fine gas defects around them and reducing selectivity.

[0062] Moreover, as the operating temperature increases, the adsorption of CO2 onto the surface of the zeolite particles is hindered, further reducing the selectivity of these membranes at high temperatures. To improve the permeability of thin film composite membranes, it is possible to make the active layer thinner, and by increasing the speed of roll-to-roll casting, it may be possible to improve the uniformity of larger-scale membranes.

[0063] The inventors have developed new compositions and new methods for optimizing the composition of these mixtures to produce MMMs with superior CO2 / CH4 separation selectivity and CO2 permeability when used under operating conditions of mixed gas, high pressure, and / or high temperature.

[0064] The present invention will be described hereinafter in the context of gas separation, particularly CO2 / CH4 separation, but it should be considered that the present invention is not limited to CO2 / CH4 and gas separation. The compositions of the present invention can be implemented in many different technical fields such as filtration, purification, gas generation, etc. using various fluids or plasmas.

[0065] In particular, the inventors have developed a new mixture of polymeric IL / free IL and zeolite. Here, the free IL is a charged surfactant which is an IL-based oligomer containing three or more repeating units.

[0066] Accordingly, according to one aspect of the present invention, a composition for producing a mixed matrix membrane is preferably provided. The composition according to the present invention may include: - at least one porous solid additive having a charged surface; - a charged surfactant; and - a polymerizable ionic liquid monomer.

[0067] The composition according to the present invention advantageously includes a charged surfactant. Preferably, the charged surfactant is an IL-based oligomer, and more preferably the IL-based oligomer contains three or more repeating units.

[0068] The IL-based oligomer may contain 30 or fewer repeating units, preferably 20 or fewer repeating units, more preferably 15 or fewer repeating units, and even more preferably 10 or fewer repeating units.

[0069] Preferably, the IL-based oligomer is an organic salt that exhibits liquid characteristics at a temperature of at least 0 °C to 100 °C.

[0070] Furthermore, the IL-based oligomer is charged in order to refer to a charged surfactant. Thus, the IL-based oligomer according to the present invention can have multiple charges. For example, the IL-based oligomer will have at least two charges, preferably at least three charges.

[0071] IL-based oligomers can contain at least two IL moieties, preferably at least three IL moieties. IL oligomers having more IL moieties per repeating unit show an improvement in CO2 solubility compared to small molecule ILs and can also increase the CO2 permeability of the new MMMs synthesized in the compositions according to the present invention.

[0072] Preferably, the IL-based oligomers can have a high affinity for CO2. More preferably, the IL-based oligomers can contain groups having a high affinity for CO2. In certain embodiments, it will contain at least one group having a higher affinity for CO2 than other light gases. Other light gases can be selected, for example, from N2, CH4, C3H8. Preferably, they are from N2 and CH4.

[0073] Molecules or groups having a higher affinity for CO2 than other light gases can be identified using Henry's constant (mole fraction). For example, a molecule or group having a higher affinity for CO2 than other light gases can have a CO2 Henry's constant of at least 30, preferably at least 40, more preferably at least 50, and even more preferably at least 70 at 40 °C (atm).

[0074] However, the IL-based oligomers used in the present invention have a high affinity for CO2 and can also be selected according to the amount of solubilized CO2 in an experimental design at controlled temperature and pressure. Thus, an IL-based oligomer having a high affinity for CO2 can solubilize, for example, more than 0.1 mol of CO2 per liter of the IL-based oligomer. Preferably, an IL-based oligomer having a high affinity for CO2 can solubilize more than 0.2 mol of CO2 per liter of the IL-based oligomer, more preferably more than 0.4 mol of CO2 per liter of the IL-based oligomer, and even more preferably more than 0.5 mol of CO2 per liter of the IL-based oligomer.

[0075] In a preferred embodiment, the IL-based oligomer will at least contain a functional group having a high affinity for CO2. For example, a functional group having a high affinity for CO2 has an interaction energy with CO2 of -10 kJ·mol -1 that can be less than.

[0076] In a preferred embodiment, the IL-based oligomer contains at least one functional group selected from imidazolium, pyridinium, quaternary ammonium, triazolium, pyrrolidinium, piperidinium, morpholinium, azole alkane, sulfonium and / or phosphonium.

[0077] Furthermore, the charged surfactant is Tf2N - , BF4 - , N(CN)2 - , PF6 - , C(CN)3 - , B(CN)4 - , N(SO2F)2 - , TfO - , SbF6 - and contains an anion selected from the group consisting of halides and sulfonates.

[0078] Furthermore, an IL oligomer with a high IL fraction per repeating unit has improved CO2 solubility compared to small molecule ILs, and the CO2 permeability of the new MMM synthesized using it increases.

[0079] The IL-based oligomer can be synthesized through polymerization including norbornene, oxanorbornene, styrene and / or acrylate moieties.

[0080] To control uniformity and length, the composition is Tf2N -It is preferably prepared by living ring-opening metathesis polymerization (ROMP) chemistry for norbornene and oxanorbornene monomers having an imidazolium unit, thereby obtaining a uniform and length-controlled IL oligomer with an alkyl backbone and a more CO2-soluble ether backbone (for a part of the initial target IL oligomer, see Figure 2).

[0081] Advantageously, ROMP is compatible with a wide range of chemical groups and has high molecular weight control and low polydispersity.

[0082] Alternatively, instead of using living ROMP to prepare IL oligomers of controlled length from IL monomers containing reactive norbornene or oxanorborene groups, controlled radical polymerization methods such as atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer (RAFT) can be used to prepare IL oligomers of controlled length from IL monomers containing polymerizable styrene or acrylate groups.

[0083] Such charged surfactants are shown in Figures 1, 2, and 3.

[0084] These proposed IL oligomer (ionic liquid-based oligomer) compounds can be used instead of [EMIM][Tf2N] (the current low molecular weight free IL used in some MMM compositions) to prepare new MMM compositions.

[0085] Gas permeation studies on these new MMM compositions have shown that using IL oligomers instead of normal ILs improves resistance to layering / sedimentation and supports permeation compared to [EMIM][Tf2N]. Also, by resisting CO2 plasticization at high temperatures and gas pressures, the selectivity of the MMM is improved.

[0086] To avoid local free IL defects, the compositions according to the invention propose replacing the small molecule free IL component in the MMM with a high-viscosity low molecular weight IL oligomer having a similar chemistry and charge.

[0087] IL oligomers produced using living chain-growth polymerization techniques are more uniform in size, short enough to remain liquid, yet have sufficient viscosity to withstand "settling," layering of layers, or penetration during film casting.

[0088] According to the inventors, low-viscosity small molecule IL materials are not static in the polymer matrix and may potentially undergo physical displacement under high pressure. This results in a region with a low IL content near the surface of the supply-side membrane, where gas permeation is significantly slowed. Thus, the lower gas permeability observed in the tests may be due to the "settling" or "wicking" of small molecule IL surfactants during the initial solvent casting of the MMM.

[0089] As the viscosity of these oligomers increases, the resistance to the flow of the oligomers increases, functioning to avoid the IL concentration gradient near the supply-side membrane surface due to a mechanical stress of 40 bar.

[0090] Advantageously, IL-based oligomers can have a viscosity exceeding 100 centipoise when measured at 20 °C using an absolute viscometer. Optionally, the IL-based oligomers can have a molecular weight exceeding 500 g / mol -1 preferably exceeding 700 g / mol -1 more preferably exceeding 1000 g / mol -1 and can have a molecular weight less than 5000 g / mol -1 preferably less than 4000 g / mol -1 more preferably less than 3000 g / mol -1 and can have a molecular weight less than.

[0091] Furthermore, it is advantageous that the IL-based oligomers do not contain moieties that can react with polymerizable ionic liquids in radical polymerization reactions.

[0092] As described above, the composition for producing the mixed matrix membrane preferably contains at least one porous solid additive having a charged surface.

[0093] At least one porous solid can preferably be either porous, microporous or nanoporous. More precisely, at least one porous solid can be either mesoporous with pores (diameter) of a size between 2 and 50 nm, or microporous with pores of a size less than 2 nm.

[0094] In particular, the porous solid additive can be a nanoporous solid additive or a microporous solid additive.

[0095] For example, the porous solid additive can be selected from zeolites, metal peroxides, zeolitic imidazolate frameworks and metal organic frameworks.

[0096] Preferably, at least one porous solid can contain zeolite. According to the present invention, at least one porous solid can be selected from zeolites, metal peroxides, zeolitic imidazolate frameworks and organometals.

[0097] More preferably, when at least one porous solid contains zeolite, the zeolite contains silicoaluminophosphate, aluminosilicate, silicate, or alkali metal aluminosilicate. The zeolite can contain Ge, Ga, Ti, V, Fe, or B.

[0098] Preferred zeolites can be selected from zeolite-A, ZSM-5, eolite-13X, zeolite-KY, silicalite-1, SSZ-13, and SAPO-34.

[0099] Preferred mesoporous materials can be selected from MCM-41, MCM-48, SBA-11, SBA-12, SBA-15, mesoporous ZSM-5, activated carbon, TiO2, and MgO.

[0100] Zeolites can also include a framework structure as a MOF.

[0101] A MOF is a compound having metal ions or clusters coordinated to organic molecules to form a one-dimensional, two-dimensional, or three-dimensional structure that can be porous. The MOF itself has been demonstrated to have a very high gas adsorption capacity, which generally suggests that gases diffuse easily through the MOF when incorporated into a membrane. However, it has been discovered that MOFs bonded to a polymer membrane via covalent, hydrogen, or van der Waals interactions create membranes with improved permeability and selectivity parameters because there are no voids or substantially no voids (no voids exist at the polymer-MOF interface or voids less than a few angstroms exist). According to one embodiment, the MOF can be chemically modified to use linkers having pendant functional groups for post-synthesis modification.

[0102] In some embodiments, the MOF is a zeolitic imidazolate framework (ZIF). A ZIF is a subclass or species of MOF and has attractive properties such as a high specific surface area, high stability, and a chemically flexible framework.

[0103] In a further aspect, the imidazolate structure or derivative can be further functionalized to impart functional groups that cover the inside of the cages and channels, particularly the pores, to obtain a desired structure or pore size.

[0104] The composition according to the present invention also includes a polymerizable ionic liquid such as a polymerizable ionic liquid monomer.

[0105] The polymerizable IL can include less than three repeating units.

[0106] Preferably, the polymerizable IL comprises one polymerizable group configured to react with the polymerizable groups of another polymerizable ionic liquid to form a polymer in a radical polymerization reaction, and at least one group having a higher affinity for CO2 than for other light gases, and preferably, the at least one group having a higher affinity for CO2 comprises phosphonium; ammonium; imidazolium; and / or pyridinium.

[0107] The composition can include at least two polymerizable IL monomers to form a block copolymer within the mixed matrix membrane.

[0108] In particular, according to one embodiment of the present invention, the composition can include a crosslinking agent.

[0109] Furthermore, by using an optimal amount of a crosslinking agent with higher CO2 selectivity, which is optimal for the preparation of the PIL matrix of these MMMs, the CO2 plasticization that leads to a decrease in CO2 / CH4 selectivity under operating conditions of high temperature and high CO2 pressure is reduced or alleviated.

[0110] As described above, by replacing the "free IL" component with these IL oligomers, the viscosity of the "interface" component increases. This reduces the likelihood of the material being lost to the underlying support or "settling" to cause a non-uniform distribution of the surfactant across the length of the membrane. Furthermore, blending these oligomers into the polymer forms a "graft polymer network" with higher resistance to plasticization and swelling.

[0111] The crosslinking agent may include at least two polymerizable groups configured to react with the polymerizable IL monomer in a radical polymerization reaction, and the polymerizable groups preferably include double bonds.

[0112] The crosslinking agent may also include at least one polar group.

[0113] Several polymerization and crosslinking solutions have been proposed. The inventors of the present invention have determined that a crosslinking agent containing at least two polymerizable groups configured to react in a radical polymerization reaction provides the best results for the present invention.

[0114] Advantageously, the crosslinking agent may include at least one group having a higher affinity for CO2 than for other light gases.

[0115] The high affinity can be considered as an affinity for CO2 higher than that of the benzene ring for CO2.

[0116] In a preferred embodiment, the crosslinking agent will at least include a functional group having a high affinity for CO2. For example, a functional group having a high affinity for CO2 may have an interaction energy with CO2 of less than -10 kJ·mol -1 It can be less than.

[0117] In a preferred embodiment, the crosslinking agent includes at least one functional group selected from the following: - A functional group containing at least one π bond containing a heteroatom, - Imidazolium, pyridinium, quaternary ammonium, triazolium, pyrrolidinium, piperidinium, morpholinium, azole alkane, sulfonium, phosphonium; and / or - Polar groups such as ethylene glycol, polyol, fluoroalkyl, aromatic ring, nitrile.

[0118] According to another aspect, the present invention relates preferably to a mixed matrix membrane for gas separation. The mixed matrix membrane is formed from the composition according to the present invention.

[0119] In particular, such a mixed matrix membrane includes the following: - At least one porous solid additive having a charged surface; - A charged surfactant; and - A polymerized ionic liquid; Here, the charged surfactant is an ionic liquid-based oligomer containing three or more repeating units.

[0120] The mixed matrix membrane can be used for gas separation and allows the passage of a desired gas component, preferably carbon dioxide and methane.

[0121] The membrane can allow the passage of gaseous components at different diffusion rates such that one of the components, for example, either carbon dioxide or methane, diffuses through the membrane at a faster rate. In a preferred embodiment, the rate at which carbon dioxide passes through the polymer is at least 10 times faster than the rate at which methane passes through the polymer.

[0122] With the mixed matrix membrane having a charged surfactant as an IL-based oligomer containing three or more repeating units, the membrane can exhibit better CO2 / CH4 separation selectivity and CO2 permeability.

[0123] To improve the permeability of the membrane, it is possible to make the active layer thinner, and by increasing the speed of roll-to-roll casting, it is possible to improve the homogeneity of larger-scale membranes.

[0124] Generally, the thickness of the thin film can be selected such that the mechanical stability of the membrane is appropriately improved.

[0125] The greater the thickness of the thin film, the lower the permeability of the thin film. Therefore, the thickness is selected such that an acceptable compromise is achieved between permeability and mechanical stability.

[0126] The membrane can be rigid, rubbery, or flexible.

[0127] The mixed matrix membrane is preferably in the form of a film, tube, or other conventional shapes used for gas separation.

[0128] According to another aspect, the present invention relates to a separation system comprising a membrane according to the present invention.

[0129] The separation system is preferably a gas separation system.

[0130] The separation system may include an outer perforated shell surrounding one or more inner tubes containing a mixed matrix membrane.

[0131] The separation system may also have at least an inlet and at least an outlet. The inlet can supply fluid, preferably gas, to the system, and contaminants can be discharged from the outlet.

[0132] For example, the gaseous mixture passes upward through the inner tube. As the gaseous mixture passes through the inner tube, one or more components of the mixture penetrate through the mixed matrix membrane from the inner tube.

[0133] The mixed matrix membrane can be included in a cartridge and used to permeate contaminants from the gaseous mixture. The contaminants can permeate through the membrane, while the desired components continue to exit out from the top of the membrane. The membranes can be stacked within a porous tube to form an inner tube or interconnected to form a self - standing tube.

[0134] Each of the mixed matrix membranes can be designed to permeate one or more components of the gaseous mixture.

[0135] The membrane can be removable and replaceable within the system. Thus, the system can also be provided with membranes arranged in series, parallel, or in combination.

[0136] Advantageously, the separation system including the membrane may have a variable length.

[0137] The gaseous mixture can flow through the membrane according to an inner - to - outer flow path or an outer - to - inner flow path.

[0138] The membrane is preferably durable, resistant to high temperatures, and resistant to high pressures as described, thus improving the durability of the system and also improving durability over time.

[0139] According to another aspect, the present invention relates to a method for producing a mixed matrix membrane.

[0140] The MMM can be formed by polymerization, preferably by any method that enables radicals. More preferably, the MMM can be formed by ROMP.

[0141] Advantageously, ROMP is compatible with a wide range of chemical groups and has high molecular weight control and low polydispersity.

[0142] The method according to the present invention includes the following: - A living or controlled chain-growth polymerization step based on a polymerizable IL containing less than 3 repeating units; - And a step of coating at least one porous solid additive having a charged surface with a charged surfactant, wherein the charged surfactant is an IL-based oligomer containing 3 or more repeating units

[0143] As already mentioned, plasticization can be mitigated by an IL-based oligomer having 3 or more repeating units.

[0144] The method according to the present invention may include a step of synthesizing a charged surfactant by synthesizing an IL oligomer of a controlled length, a ring-opening metathesis polymerization (ROMP) step, and a step of controlling chain-growth polymerization.

[0145] Preferably, the control of the length of the charged surfactant is based on the control of ring-opening metathesis polymerization (ROMP) or chain-growth polymerization. Using an IL-based oligomer having 3 or more repeating units instead of a small molecule IL in the preparation of the MMM can improve gas permeability and selectivity.

[0146] Furthermore, the use of IL-based oligomers (i.e., IL oligomers of controlled length) can reduce aggregation in the center of the cross-section of the MMM film during casting. Advantageously, the IL oligomers of controlled length avoid the "IL defect" region. There is no longer any free IL for IL oligomers having more than three repeating units, and the oligomers of controlled length are more static than free IL and are less susceptible to physical displacement under high pressure. As a result, a mixed matrix membrane with uniform redivision is obtained, and the gas permeability is significantly improved.

[0147] IL-based oligomers produced using living or controlled chain-growth polymerization techniques such as ROMP, ATRP, RAFT have a uniform size and are short enough to remain liquid, but have a viscosity sufficient to resist "sedimentation", layering of layers, or penetration of the support during film casting.

[0148] Furthermore, the resulting mixed matrix membrane resembles a graft polymer and has excellent resistance to plasticization and swelling.

[0149] To improve this method, a ROMP step can be performed on a simple imidazolium-based norbornene monomer to produce uniform and low molecular weight IL oligomers and block copolymers, including the first type of proposed IL oligomers shown in Figure 1.

[0150] ROMP is a chain-growth polymerization that converts cyclic olefins into polymer materials in the presence of transition metal-based complexes such as Ti, Mo, W, Ta, Re, Ru. ROMP is a type of olefin metathesis polymerization, and the driving force of the reaction is the relaxation of the ring strain of cyclic olefins (e.g., norbornene, cyclopentene). Therefore, the conversion reaction of both polycyclic olefins (including norbornene; norbornadiene; dicyclopentadiene and low-strain cyclic olefins including cyclopentene; or cycloheptene, etc.) can expand the range of achievable chain polymers.

[0151] In ROMP, polymer chains can be formed by including strained ring functional groups such as norbornene functional groups and cyclopentene functional groups in the monomers. For example, norbornene is a bridged cyclic hydrocarbon having a cyclohexene ring bridged with a methylene group at the para position.

[0152] In the ROMP process, following the formation of metal carbene species, the double bond within the ring structure is attacked by the carbene, forming a highly strained metallacyclobutane intermediate. Subsequently, the ring opens, forming the start of the polymer. The straight chain binds to the metal with a double bond, and a terminal double bond is also formed. The new carbene reacts with the double bond of the next monomer, and the reaction propagates.

[0153] An important step in the synthesis of ROMP is the chain transfer process at the end. ROMP is widely terminated by the addition of agents containing specific functional groups. This agent inactivates the transition metal catalyst from the end of the growing chain and selectively inserts the functional group.

[0154] As with all metathesis reactions, it is important to note that in principle all steps are reversible. Furthermore, the double bond of the monomer is formally conserved, and one double bond occurs for each repeating unit. This high degree of unsaturation of the resulting ROMP affects the stability of the resulting polymer against oxygen.

[0155] Alternatively, instead of using living ROMP to prepare IL oligomers with controlled lengths, controlled radical polymerization methods such as atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization can also be used.

Example

[0156] The present invention will be described in more detail with reference to the following experimental examples. These examples are provided for illustrative purposes only and are not intended to be limiting, unless otherwise specified. Therefore, the present invention should in no way be construed as being limited to the following examples, but rather should be construed as encompassing any variations that become apparent as a result of the teachings provided herein.

[0157] Even without further explanation, those skilled in the art would be able to manufacture and utilize the compounds of the present invention and implement the methods described in the claims using the foregoing description and the following exemplary embodiments. Therefore, the following examples specifically point out preferred embodiments of the present invention and should not be construed as limiting the remainder of the present disclosure in any way.

[0158] As described in detail, the present invention involves the use of ionic liquid (IL)-based oligomers in MMMs. These examples are specifically directed to such aspects.

[0159] 1. Material CO2, CH4, and He gas were of ultra-high purity (99.999%) purchased from Airgas.

[0160] 1-Vinyl-3-methylimidazolium bis(triflimide) ([VMIM][Tf2N]) and 1-ethyl-3-methylimidazolium bis(triflimide) ([EMIM][Tf2N]) were synthesized according to the methods of previously published literature (S. Li, J.L. Falconer, R.D. Noble, Improved SAPO-34 Membranes for CO2 / CH4 Separations, Adv. Mater. 18, (2006) 2601-2603. https: / / doi.org / 10.1002 / adma.200601147). And their structures were 1 confirmed by 1H NMR spectroscopy and were consistent with the reported characteristic data (Li et al., 2006).

[0161] The crosslinking compound divinylbenzene (DVB) and radical photoinitiators such as 2-hydroxy-2-methylpropiophenone (HMP) were purchased from Sigma-Aldrich and used as received.

[0162] SAPO-34 was synthesized using the procedure reported in the literature (Y. Zheng, N. Hu, H. Wang, N. Bu, F. Zhang, R. Zhou, Preparation of steam-stable high-silica CHA (SSZ-13) membranes for CO2 / CH4 and C2H4 / C2H6 separation, J. Membr. Sci. 475 (2015) 303-310. https: / / doi.org / 10.1016 / j.memsci.2014.10.048). SAPO-34 was calcined at 600 °C and finely ground with a mortar and pestle before use.

[0163] 2. Ionic liquid (IL)-based oligomer The performance of MMMs containing [VMIM][Tf2N] or [EMIM][Tf2N] can be compared with that of MMMs containing IL-based oligomers instead.

[0164] Some molecules that can be used as IL-based oligomers. IL-based oligomers can be synthesized using ring-opening metathesis polymerization (ROMP).

[0165] Alternatively, IL-based oligomers can also be synthesized using controlled radical polymerization methods such as ATRP and RAFT. These techniques are efficient and scalable methods for producing IL oligomers of controlled length, especially from IL-based styrene and / or acrylate monomers.

[0166] RAFT As shown in Figure 1, IL-based oligomers can be synthesized by controlled RAFT polymerization.

[0167] In particular, in the controlled sequential polymerization, α-chloromethylstyrene (CMS), cyanomethyl dodecyl trithiocarbonate as a chain transfer agent, azobis(isobutyronitrile) (AIBN) as a radical initiator, and N,N-dimethylformamide (DMF) as a polymerization solvent can be used.

[0168] The purified CMS was dissolved in DMF and added to a Schlenk flask equipped with a magnetic stir bar. Subsequently, cyanomethyl dodecyl trithiocarbonate, which is a RAFT agent, was added to the flask. Next, AIBN was added to the flask and stirring was initiated to mix the reagents. An Ar gas blanket was passed through the flask to displace the external atmosphere. The contents of the reaction flask were degassed by repeating a free-pump thaw cycle using liquid nitrogen until a negligible pressure rise was detected upon evacuation. Once the final thaw cycle was complete, Ar gas was flowed into the flask under positive pressure and a reflux condenser was attached. The condenser was sealed and the Ar flow was blocked. Next, the sealed reaction system was placed in an oil bath set at a temperature of 70 °C and the contents were rapidly stirred. After stirring at that temperature for 24 hours, the reaction flask was removed from the heat and allowed to cool to ambient temperature. Subsequently, the polymer solution was added dropwise to a 1 L Erlenmeyer flask containing 700 mL of rapidly stirred methanol. The precipitated polyCMS oligomers appeared as pale yellow "chips" of solid material. After decanting the methanol, the polyCMS oligomers were dried in vacuo at 40 °C overnight.

[0169] The IL oligomers were prepared by reacting the polyCMS oligomers with an excess of N-methylimidazole such that all chloromethyl groups were substituted with the IL moiety. The polyCMS oligomers were added to a 50 mL round-bottom flask equipped with a magnetic stir bar together with DMF. This mixture was stirred until the polymer was completely dissolved. A reflux condenser was attached to the flask, and the flask was heated to 70 °C and maintained at that temperature. Then, to avoid irreversible gelation of the reaction mixture, N-methylimidazole and methanol were added to the flask without cooling the flask. When this reaction was carried out by refluxing at 70 °C for 24 h, a curable polymer of the Cl-intermediate was obtained. The intermediate polymer was dissolved in 50 mL of deionized (DI) H2O. 1.5 molar equivalents in excess of LiTf2N (11.0 g, 38.32 mmol) was dissolved in 350 mL of DIH2O. When the aqueous solution of the intermediate polymer was added dropwise to the rapidly stirred LiTf2N solution, an off-white rubber was immediately formed. This new precipitate was the Tf2N - substituted curable IL oligomer.

[0170] Alternatively, as shown in Figure 2, the IL-based oligomers can be synthesized by the controlled RAFT polymerization of ILs containing vinylbenzyl ([VBMI][Tf2N], etc.) using cyanomethyl dodecyl trithiocarbonate as a chain transfer agent and azobis(isobutyronitrile) (AIBN) as a radical initiator and N,N-dimethylformamide as a polymerization solvent.

[0171] Briefly, the purified [VBMI][Tf2N] was dissolved in DMF and added to a Schlenk flask equipped with a magnetic stir bar. Next, cyanomethyl dodecyl trithiocarbonate, which is a RAFT agent, was added to the flask. Then, AIBN was added to the flask and stirring was started to mix the reagents. An Ar gas blanket was passed through the flask to displace the external atmosphere. The contents of the reaction flask were degassed by repeating a free-pump thaw cycle using liquid nitrogen until a negligible pressure increase was detected upon evacuation. Once the final thaw cycle was complete, Ar gas was flowed into the flask under positive pressure and a reflux condenser was attached. The condenser was sealed and the Ar flow was blocked. Next, the sealed reaction system was placed in an oil bath set at a temperature of 70 °C and the contents were rapidly stirred. After stirring at that temperature for 24 hours, the reaction flask was removed from the heat and allowed to cool to ambient temperature. Then, the polymer solution was dropped into a 1 L Erlenmeyer flask containing 700 mL of rapidly stirred methanol. The precipitated material was the IL oligomer.

[0172] ATRP As shown in Figure 3, the IL-based oligomer can be synthesized via ATRP using CuBr / N,N,N’,N’,N”-pentamethyldiethylenetriamine (PMDETA) as the catalyst system and 2-(trimethylsilyl)ethyl 2-bromoisobutyrate in a butyronitrile solution as the initiator.

[0173] [VBMI][Tf2N], IL monomers such as PMDETA and butyronitrile were added to a flame-dried Schlenk flask and degassed by repeating the freeze-pump-thaw cycle three times. After warming the flask to room temperature and refilling with Ar, CuBr was added. The resulting mixture was stirred at room temperature for 30 minutes and finally a macroinitiator containing styrene was added. Next, the flask was placed in an oil bath at 90 °C and stirred. When the IL monomer was completely consumed (confirmed by 1H NMR analysis), the resulting reaction mixture was purified to obtain the IL-based oligomer.

[0174] Similar IL-based acrylate monomers can also be used to perform similar polymerizations by ATRP and RAFT (not shown).

[0175] 3. MMM synthesis Self-standing MMMs were synthesized by combining polymerizable ILs such as polymerizable IL monomers, charged surfactants, and porous solid additives (such as SAPO-34) having a charged surface in an appropriate weight ratio.

[0176] This mixture was stirred for 24 hours, followed by the addition of 0.5 - 6 wt% cross-linking agent (based on the total mass of the IL-based components) and 0.5 - 2 wt% radical photoinitiator such as 2-hydroxy-2-methylpropiophenone (based on the total mass of the IL-based components).

[0177] After gently stirring this mixture, it was cast onto a quartz plate treated with Rain-X (trademark). Two 150-μm-thick slide glasses were used as spacers, and a second Rain-X (trademark)-treated plate was placed on top of the mixture to form a film. The plates were clamped together and irradiated with a 365 nm UV lamp (4.3 mW / cm 2 ) at 17 °C for 5 hours. Next, the plates were separated and placed in a vacuum oven at 50 °C (20 torr) for 24 hours.

[0178] Next, the film was peeled off one of the plates, placed in a Petri dish, and stored under static vacuum or immediately prepared for gas permeability evaluation. The thickness of the resulting self-standing MMM film can be measured using a digital micrometer. The thickness range is usually 120 - 160 μm.

[0179] Reference MMM films were prepared using free ILs, and the MMM films of the present invention were prepared using ionic liquid (IL)-based oligomers containing three or more repeating units. The ionic liquid (which can be an oligomer) is preferably added at a loading level such that the resulting MMM contains the same number of imidazolium groups.

[0180] 2.3. Gas permeability measurement The gas permeability of the MMM samples was measured using a custom-built apparatus equipped for high pressure and binary gas supply, following the procedure below. A circular membrane piece was loaded into the lower half of a steel test cell, a rubber gasket was placed on top of it, the upper half of the cell was placed on top of that, and it was fixed with screws. The supply flow rate and composition could be controlled via LabView software by a pair of mass flow controllers (MFCs) attached to CO2 and CH4 cylinders. Since the supply flow rate is orders of magnitude larger than the permeation rate, it can be assumed that the composition of the supply component and the holding liquid are equal.

[0181] A third MFC was used to provide a sweep stream of He on the permeate side of the membrane. Both the feed / residue stream and the permeate stream were monitored by an in-line SRI8610C gas chromatograph (GC) equipped with a 6 m long Haysep D column operating at 50 °C. The feed pressure was selected using a back pressure regulator on the feed side, and the pressures of the feed stream and the permeate stream were monitored with digital gauges. The flow rates of the permeate water and the residual water were measured using a bubble flow meter and a stopwatch. The membrane cell was placed inside a Yamato DX300 oven, and gas permeation measurements of the MMM samples were performed at various elevated temperatures. Using the GC composition data, flow rates, and pressure combinations, the CO2 and CH4 permeabilities, and the CO2 / CH4 selectivity of each MMM sample were calculated.

[0182] Such experiments can confirm that the MMM according to the present invention is designed to alleviate the problem of CO2 plasticization and reduce swelling by CO2 at higher pressures and temperatures. Furthermore, the MMM according to the present invention has high CO2 permeability and high CO2 / CH4 selectivity.

[0183] The description of a list of elements in the definition of a variable herein includes the definition of that variable as any single element or combination (or sub-combination) of the listed elements. The description of an embodiment herein includes that embodiment as any single embodiment, or in combination with any other embodiment or part thereof.

[0184] The disclosures of all patents, patent applications, and publications cited in this specification are hereby incorporated by reference in their entirety, except for definitions, disclaimers of subject matter, or denials, except where the incorporated material is inconsistent with the explicit disclosure of this specification (in which case the language of this disclosure shall control).

[0185] Although the invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and modifications of the invention may be devised by those skilled in the art without departing from the true spirit and scope of the invention. The appended claims are intended to be construed to include all such embodiments and equivalent modifications.

Claims

1. A composition comprising: - at least one porous solid additive having a charged surface; - a charged surfactant; and - a polymerizable ionic liquid which is a monomer or oligomer polymerizable at room temperature; wherein the charged surfactant is an ionic liquid (IL)-based oligomer comprising three or more repeating units, and the IL-based oligomer is non-polymerizable at room temperature.

2. The composition according to claim 1, wherein the IL-based oligomer is based on polymerized norbornene, oxanorbornene, styrene and / or acrylate moieties.

3. The composition according to claim 1 or 2, wherein the IL-based oligomer is based on polymerized styrene moieties and / or acrylate moieties.

4. wherein the charged surfactant is Tf 2 N - , BF 4 - , N(CN) 2 - , PF 6 - , C(CN) 3 - , B(CN) 4 - , N(SO 2 F) 2 - , TfO - , SbF 6 - The composition according to any one of claims 1 to 3, comprising an anion selected from the group consisting of halides and sulfonates.

5. The composition according to any one of claims 1 to 4, wherein the at least one porous solid is selected from zeolites, metal peroxides, zeolitic imidazolate frameworks and metal-organic frameworks.

6. The composition according to any one of claims 1 to 5, wherein the at least one porous solid additive is selected from: - Zeolites: Zeolite A, ZSM-5, Zeolite-13X, Zeolite-KY, Silicalite-1, SSZ-13, SAPO-34; - MCM-41, MCM-48, SBA-11, SBA-12, SBA-15, mesoporous ZSM-5, activated carbon, TiO2, MgO; and / or ・ MIL-96, MIL-100, MOF-5, MOF-177, ZIF-7, ZIF-8, Cu-TPA, Cu 3 (BTC) 2 , Cu-BPY-HFS.

7. The composition according to any one of claims 1 to 6, further comprising a crosslinking agent.

8. The composition according to any one of claims 1 to 7, wherein the polymerizable ionic liquid comprises less than three repeating units.

9. A mixed matrix membrane formed from the composition according to any one of claims 1 to 8.

10. A mixed matrix membrane comprising: - at least one porous solid additive having a charged surface; - a charged surfactant; and - a polymerizable ionic liquid which is a monomer or oligomer polymerizable at room temperature; wherein the charged surfactant is an ionic liquid-based oligomer comprising three or more repeating units, and the ionic liquid-based oligomer is non-polymerizable at room temperature.

11. Use of the mixed matrix membrane according to claim 9 or 10 for gas separation.

12. Use according to claim 11 for the separation of CO in a mixed gas at pressures higher than 40 bar 2 as claimed in claim 11 for the separation of CO in a mixed gas at pressures higher than 40 bar

13. The use according to claim 11 for the separation of CO in a mixed gas at a temperature higher than 50 °C 2 thereof.

14. CO at pressures higher than 50 bar and temperatures higher than 60 °C in a mixed gas 2 Use according to claim 11 for the separation thereof.

15. A method for manufacturing the mixed matrix membrane according to claim 10, - Obtaining the polymerizable ionic liquid by living chain-growth polymerization based on a polymerizable IL containing less than three repeating units, - And coating at least one porous solid additive having a charged surface with a charge surfactant A method comprising.

16. The method for producing a mixed matrix membrane according to claim 15, comprising a step of controlling living chain-growth polymerization.

17. The method for producing a mixed matrix membrane according to claim 16, comprising a step of synthesizing an IL oligomer with controlled length.

18. The method for producing a mixed matrix membrane according to any one of claims 15 to 17, comprising a ring-opening metathesis polymerization (ROMP) step.

19. The method for producing a mixed matrix membrane according to any one of claims 15 to 18, comprising the formation of an ultrathin layer.

20. A separation system comprising the mixed matrix membrane according to claim 9 or 10.

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