Thin layer composite ionic liquid supported liquid membranes, continuous process for their preparation and use

Abstract

The application discloses a kind of thin layer composite ionic liquid supported liquid membrane and its continuous preparation method and application in gas separation.The thin layer composite ionic liquid supported liquid membrane includes a layer of nanometer microporous film and a layer of inert porous membrane with ionic liquid, and the two are closely adhered to form the thin layer composite ionic liquid supported liquid membrane.The application utilizes interface polymerization to quickly and conveniently synthesize a layer of structure controllable nanometer microporous film on the surface of ionic liquid supported liquid membrane, realizes the continuous preparation of thin layer composite ionic liquid supported liquid membrane.The smaller pore size of nanometer microporous film can provide greater capillary force, improve the ultimate breakdown pressure and long-term stability of composite membrane.The affinity of nanometer microporous film and inert porous membrane inner wall to ionic liquid will jointly ensure that ionic liquid continuously and stably exists in its pore, realizes the running stability of thin layer composite ionic liquid supported liquid membrane in actual gas separation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of membrane preparation, in particular to a thin layer composite ionic liquid supported liquid membrane, a continuous preparation method thereof and application thereof. BACKGROUND

[0002] The supported liquid membrane is an artificial thin film formed by attaching an organic solvent or inorganic solvent containing an extractant in the pores of an inert porous membrane, and is widely used in gas separation, organic matter separation, metallurgy, wastewater treatment and other fields.

[0003] The ionic liquid is a kind of extractant commonly used in the supported liquid membrane, which is composed of anions and cations and is in a liquid state at room temperature or near room temperature. The ionic liquid usually has excellent solubility for certain specific molecules, and has the characteristics of adjustable structure, non-volatility, appropriate viscosity and good thermal and chemical stability, and thus is suitable for being used as an extractant for preparing the supported liquid membrane. For example, the fluoroborate ionic liquid has strong specific solubility for carbon dioxide. The ionic liquid supported liquid membrane prepared by using the fluoroborate ionic liquid as an extractant can effectively separate carbon dioxide in a mixed gas (for example, patents KR20160011473A and US2014283839A1). However, the supported liquid membrane only relies on the capillary effect of the membrane pores to support the ionic liquid extractant, and in the actual gas separation process, the ionic liquid will be continuously lost under long-term high-pressure gas blowing, eventually leading to the breakdown and failure of the supported liquid membrane.

[0004] To overcome the poor stability of supported liquid membranes in gas separation processes, two main approaches are used: reducing the pore radius of the inert porous membrane used as a support or using nanomaterials and polymer cross-linked networks to lock and limit the flow of ionic liquids. For example, Gan et al. (J Membr Sci, 2006, 280, 948.) supported several ionic liquids on nanofiltration membranes as inert support substrates for gas separation. The nanofiltration membrane has a small pore size, which provides sufficient capillary force. The resulting supported liquid membrane can be stably operated at a working pressure of 3.0-7.0 bar, which is much higher than the pressure resistance of a conventional microfiltration membrane as an inert support substrate. For another example, imidazole-type ionic liquids added with gelator nanometer SiO2 and carbon nanotubes are fixed in the pores of PVDF membrane, PTFE membrane, PS membrane, PES membrane, nylon membrane, silica membrane or porous Al2O3 membrane substrate by impregnation and pressure penetration to obtain a relatively stable supported liquid membrane at high pressure (for example, patent CN201210124953.X). The supported liquid membrane can be stably operated for more than 24 h at a transmembrane pressure difference of 100-200 kPa, and an ideal separation ratio of CO2 / CH4 of 8-25 is achieved. Although the above methods effectively improve the pressure resistance and stability of the supported liquid membrane, the preparation process is relatively complicated, and inevitably causes a significant reduction in the permeation flux of the supported liquid membrane. Therefore, it is necessary to propose a new structure of supported liquid membrane and a convenient preparation method thereof, which can improve the stability of the supported liquid membrane at high pressure and in long-term operation while ensuring the gas permeation efficiency as much as possible. SUMMARY

[0005] The present application provides a thin-layer composite ionic liquid supported liquid membrane and a continuous preparation method thereof, which can be stably operated at high operating pressure for a long time, thereby reducing the operation and maintenance costs.

[0006] The technical scheme of the present application is as follows:

[0007] A thin-layer composite ionic liquid supported liquid membrane comprises a nanometer microporous membrane and an inert porous membrane supporting ionic liquid, and the nanometer microporous membrane and the inert porous membrane supporting ionic liquid are tightly attached to form a double-layer structure.

[0008] In the present application, a nanometer microporous membrane is loaded on the surface of the ionic liquid supported liquid membrane. The ionic liquid in the original supported liquid membrane no longer directly forms a large-scale interface with air. The smaller pore diameter of the nanometer microporous membrane can provide greater capillary force, thereby improving the ultimate breakdown pressure and long-term stability of the composite membrane. The affinity of the nanometer microporous membrane and the inner wall of the inert porous membrane to the ionic liquid will jointly ensure the continuous and stable existence of the ionic liquid in the pores thereof, thereby improving the operation stability of the ionic liquid supported liquid membrane.

[0009] Preferably, the nano-porous membrane is a polyamide membrane with a thickness of 1-10000 nm and a pore size of 0.1-10 nm.

[0010] The suitable thickness of the nano-porous membrane provides strength and avoids causing large membrane resistance; the relatively small pore size provides sufficient capillary force to avoid the loss of ionic liquid.

[0011] Further preferably, the nano-porous membrane has a thickness of 50-250 nm and a pore size of 0.1-5 nm.

[0012] Preferably, the inert porous membrane has a pore size of 0.1-100 μm and a porosity of 1-99%.

[0013] The relatively small pore size of the inert porous membrane is conducive to supporting the nano-porous membrane without being crushed, thereby fully showing the pressure resistance of the thin-layer composite ionic liquid supported liquid membrane; the relatively high porosity is conducive to the permeation of gas.

[0014] Further preferably, the inert porous membrane has a pore size of 0.2-1.5 μm and a porosity of 40-99%.

[0015] Preferably, the inert porous membrane is made of at least one of ceramic, metal and polymer.

[0016] Further preferably, the ceramic is at least one of Al2O3, SiO2, MgO, ZrO2 and TiO2; the metal is at least one of gold, silver, palladium, titanium and vanadium; and the polymer is at least one of cellulose nitrate, cellulose acetate, ethyl cellulose, mixed cellulose, polysulfone, polyether sulfone, polyamide, polysulfonamide, polyethylene, polypropylene, polyvinyl chloride, polycarbonate, polytetraethylene and polyvinylidene.

[0017] Preferably, the ionic liquid has a melting point of -100-100℃ and a viscosity of 10-1000 cP.

[0018] Further preferably, the cation of the ionic liquid is at least one of alkyl quaternary ammonium ion, alkyl quaternary phosphonium ion, N,N'-dialkyl-substituted imidazolium, N-alkyl-substituted pyridinium, amino-substituted imidazolium, amino-substituted pyridinium, glycine, alanine, valine, leucine, isoleucine and methionine; and the anion of the ionic liquid is at least one of halide, tetrachloroaluminate, hexafluoroaluminate, tetrafluoroborate, hexafluorophosphate, nitrate, perchlorate, trifluoroacetate, trifluoromethanesulfonate, bistrifluoromethanesulfonylimide, p-toluenesulfonate, perfluorobutyrate, perfluorobutylsulfonate, hydroxypyridine, glycine, alanine, valine, leucine, isoleucine and methionine.

[0019] Further preferably, the ionic liquid is at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium triflate, and 1-butyl-3-methylimidazolium bistrifluoromethylsulfonimide.

[0020] The application also provides a method for continuously preparing the thin-layer composite ionic liquid supported liquid membrane, comprising the following steps:

[0021] (1) uniformly coating the ionic liquid solution of the reactive monomer a on the inert porous membrane to form a stable and uniform supported liquid membrane, and continuously and smoothly transporting the supported liquid membrane forward through a transmission mechanism;

[0022] (2) contacting the supported liquid membrane with the solution of the reactive monomer b to initiate an interfacial polymerization reaction and synthesize a nanometer microporous thin film on the surface of the supported liquid membrane;

[0023] (3) removing the unreacted solution of the reactive monomer b on the surface of the nanometer microporous thin film through washing and drying to obtain the thin-layer composite ionic liquid supported liquid membrane.

[0024] The application dissolves a reactive monomer a capable of participating in an interfacial polymerization in an ionic liquid and then injects the ionic liquid into the pores of an inert porous membrane to form a supported liquid membrane. Subsequently, another reactive monomer b is contacted with the ionic liquid supported liquid membrane to initiate an interfacial polymerization reaction and rapidly and efficiently form a nanometer-thickness thin film as a protective layer on the surface of the ionic liquid supported liquid membrane. The ultra-thin nanometer microporous thin layer does not greatly increase the overall gas mass transfer resistance, which helps to maintain the separation efficiency of the composite membrane.

[0025] Preferably, in step (1), the coating method of the ionic liquid solution of the reactive monomer a is one or a combination of the following methods:

[0026] (A) immersing the inert porous membrane in the ionic liquid solution of the reactive monomer a;

[0027] (B) pouring or spraying the ionic liquid solution of the reactive monomer a onto the inert porous membrane and applying a negative pressure below the inert porous membrane to draw the ionic liquid solution of the reactive monomer a into the pores of the inert porous membrane;

[0028] (C) pouring or spraying the ionic liquid solution of the reactive monomer a onto the inert porous membrane and pressing the ionic liquid solution of the reactive monomer a into the pores of the inert porous membrane by using a roller.

[0029] In method (A), the time for immersing the inert porous membrane in the ionic liquid of the reactive monomer a is 30-7200 s.

[0030] In the methods (B) and (C), the amount of the ionic liquid of the reactive monomer a poured on the inert porous membrane is 0.001-1 mL-cm -2 ;

[0031] In the method (E), the spraying rate of the solution of the reactive monomer b on the support liquid membrane is 0.0001-30 mL-cm -2 ·min -1 ; and in the method (B), the negative pressure is 0-1 atm; and in the method (C), the rolling speed is 0.01-1 m-s -1 , and the rolling pressure is 0-10 atm.

[0032] Preferably, in the step (2), the method of contacting the support liquid membrane with the solution of the reactive monomer b is one or a combination of the following methods:

[0033] (D) immersing the support liquid membrane in the solution of the reactive monomer b;

[0034] (E) spraying the solution of the reactive monomer b on the surface of the support liquid membrane.

[0035] In the method (D), the time of immersing the support liquid membrane in the solution of the reactive monomer b is 30-3600 s.

[0036] In the method (E), the spraying rate of the solution of the reactive monomer b on the support liquid membrane is 0.0001-30 mL-cm -2 ·min -1 ; and further preferably, 0.1-1 mL-cm -2 ·min -1 .

[0037] The transmission mechanism is a conveyor belt, a roller, etc.; and the material is a polymer, glass, ceramic, metal, etc.

[0038] The movement speed of the transmission mechanism is 0.002-30 m-min -1 .

[0039] Preferably, the solvent used for dissolving the reactive monomer b is a solvent incompatible with the ionic liquid.

[0040] Further preferably, the solvent used for dissolving the reactive monomer b is a non-polar solvent such as a normal alkane, an isomeric alkane, a cycloalkane, and an aromatic hydrocarbon; or a polar solvent such as an alcohol, a phenol, an epoxide, a halogenated hydrocarbon, an ester, and a ketone.

[0041] Further preferably, the solvent used for dissolving the reactive monomer b can be one or more of the following mixed: n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, naphtha, isoparaffin G, isoparaffin H, isoparaffin L, isoparaffin M, cyclopentane, cyclohexane, cycloheptane, cyclooctane, benzene, toluene, 1,2-xylene, 1,3-xylene, 1,4-xylene and 1,3,5-trimethylbenzene, methanol, ethanol, glycerol, acetonitrile, ethyl acetate, chloroform, trifluoroacetic acid, phenol, etc.

[0042] The reactive monomer a is an amine compound; the reactive monomer b is an acyl chloride compound.

[0043] The amine compound has at least two amine groups in its molecular structure; the acyl chloride compound has at least two acyl chloride groups in its molecular structure.

[0044] The reactive monomer a is at least one of ethylenediamine, butylenediamine, hexylenediamine, octylenediamine, decylenediamine, piperazine, 1,3-cyclohexanedimethylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, N,N-bis(3-aminopropyl)methylamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(4-aminophenyl)hexafluoropropane, tetra(4-aminophenyl)methane, 9,9'-bis(4-aminophenyl)fluorene, tetra(4-aminophenyl)ethylene, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, tris(4-aminophenyl)amine, 1,3,5-tris(4-aminophenyl)benzene and 1,3,5,7-tetra(4-aminophenyl)-adamantane.

[0045] The reactive monomer b is at least one of succinyl chloride, glutaroyl chloride, adipoyl chloride, suberoyl chloride, sebacoyl chloride, isophthaloyl chloride, terephthaloyl chloride, 1,2,4-benzene tricarboxylic acid chloride, 1,3,5-benzene tricarboxylic acid chloride, 1,2,4,5-benzene tetracarboxylic acid chloride, 4,4'-biphenyl dicarboxylic acid chloride, 3,5,3',5'-biphenyl tetracarboxylic acid chloride, 2,6-pyridine dicarboxylic acid chloride and 2,4,6-pyridine tricarboxylic acid chloride.

[0046] The concentration of the reactive monomer a in the ionic liquid solution of the reactive monomer a is 1-1000 mM; preferably 10-50 mM.

[0047] The concentration of the reactive monomer b in the solution of the reactive monomer b is 0.01-300 mM; preferably 0.1-1.0 mM.

[0048] Preferably, in step (1), the volume percentage of the ionic liquid solution of the reactive monomer a filled in the pores of the inert porous membrane is 1-100%.

[0049] The application also provides the application of the thin-layer composite ionic liquid supported liquid membrane in gas separation, in particular, in carbon dioxide gas separation.

[0050] The thin-layer composite ionic liquid supported liquid membrane of the application can be operated stably for a long time under high pressure of several times of atmospheric pressure, and realizes efficient gas separation. Compared with the prior art, the application has the following beneficial effects:

[0051] (1) The thin-layer composite ionic liquid supported liquid membrane of the application adds a nano-microporous film to the traditional ionic liquid supported liquid membrane, greatly improves the working pressure and working stability of the ionic liquid supported liquid membrane, so that the supported liquid membrane can be operated stably for a long time under high operating pressure, and the operation and maintenance costs are reduced.

[0052] (2) Due to the high viscosity of the ionic liquid, the interfacial polymerization is controlled by slowing down the diffusion rate of the reactants, and the thickness of the nano-microporous film of the thin-layer composite ionic liquid supported liquid membrane can be effectively controlled. At the same time, since the ionic liquid has good solubility for various amine monomers, the spatial structure of the reactive monomer a can be customized and controlled, and the porosity of the synthesized nano-microporous film can be increased. The extremely low thickness and the larger porosity can ensure that the addition of the nano-microporous film will not greatly increase the mass transfer resistance of the supported liquid membrane.

[0053] (3) The thin-layer composite ionic liquid supported liquid membrane of the application does not need to remove the ionic liquid or the dissolved reactive monomer a, and the reactive monomer a can play a role as an extraction aid in gas separation, which has the great advantages of green environmental protection, simplicity and stability.

[0054] (4) The nano-microporous film of the thin-layer composite ionic liquid supported liquid membrane of the application itself can have a certain gas separation capacity, and the membrane material obtained by using the method has strong separation capacity, and the ideal separation ratio of carbon dioxide / nitrogen is high.

[0055] (5) Due to the adjustable viscosity of the ionic liquid and the protection of the inert porous film, the method can transport the inert porous film and the supported liquid membrane on the surface of a conveying belt of various materials, and can flexibly initiate interfacial polymerization by immersing or spraying another solution of a reactant, so that the continuous and scaled preparation of the thin-layer composite ionic liquid supported liquid membrane can be conveniently and quickly realized. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 It is a structure schematic view of a preferred continuous and scaled preparation device of the thin-layer composite ionic liquid supported liquid membrane;

[0057] Figure 2 It is a cross-sectional electron microscope image (a) and a surface electron microscope image (b) of the thin-layer composite ionic liquid supported liquid membrane prepared in Example 2 after washing away the ionic liquid. DETAILED DESCRIPTION

[0058] The application will be further described in detail below in conjunction with the accompanying drawings and examples, it should be noted that the following examples are intended to facilitate the understanding of the application and do not limit the application in any way.

[0059] In the specific implementation method, the preparation device structure used is as shown in the figure, including unwinding device, conveying device, blade coating device, spraying device, washing device, drying device and winding device. Figure 1

[0060] The unwinding device is used to apply the inert porous membrane.

[0061] The conveying device and the winding device are used to convey and wind the inert porous membrane or the thin-layer composite ionic liquid supported liquid membrane at a specified speed.

[0062] The blade coating device is composed of a liquid cylinder a and a doctor blade, and the spraying device is composed of a liquid cylinder b and an atomizing nozzle. Both are placed above the conveying device, and the distance from the conveying device can be adjusted.

[0063] The preparation method includes:

[0064] (1) Prepare the ionic liquid solution of reactive monomer a and the solution of reactive monomer b, and add them to the liquid cylinder a and the liquid cylinder b respectively. Use the unwinding device to continuously apply the preferred inert porous membrane to the conveying device. The ionic liquid solution of reactive monomer a is extruded from the nozzle below the liquid cylinder a and is coated on the moving inert porous membrane by the doctor blade.

[0065] (2) The solution of reactive monomer b is sprayed on the moving inert porous membrane coated with the ionic liquid solution through the atomizing nozzle below the liquid cylinder b, and the interfacial polymerization of reactive monomer a and reactive monomer b starts immediately.

[0066] (3) The conveying device continues to move forward for a period of time, and then enters the washing device after the reaction proceeds to an appropriate degree, the same pure solvent used to dissolve the reactive monomer b in (1) is used to remove excess reactive monomer b, and the interfacial polymerization is terminated. The synthesized thin-layer composite ionic liquid supported liquid membrane enters the drying device for post-treatment to remove the solvent, and after completion, it is wound into a roll by a roller for use.

[0067] When the thin-layer composite ionic liquid supported liquid membrane prepared by the application is used in the field of gas purification and separation, the gas permeation rate Q is calculated by the following formula:

[0068]

[0069] Where P u is the inlet pressure, P d is the outlet pressure, and P atm ​P is the atmospheric pressure, T is the test temperature, A is the effective membrane area, and dV / dt is the volumetric flow rate of the flow meter during the test.

[0070] The gas separation ratio a is defined as:

[0071]

[0072] where Q1 and Q2 are the permeation rates of the two gases, respectively.

[0073] The pressure difference between the inlet and outlet ends when the gas separation ratio a suddenly drops to 0 is the breakthrough pressure.

[0074] Examples 1-4

[0075] In Example 1-4, the concentration of the reactive monomer b is 0.188 mM, 0.377 mM, 0.565 mM, and 0.753 mM, respectively.

[0076] In Example 1-4, the concentration of the reactive monomer b is 0.188 mM, 0.377 mM, 0.565 mM, and 0.753 mM, respectively.

[0077] In Example 1-4, the concentration of the reactive monomer b is 0.188 mM, 0.377 mM, 0.565 mM, and 0.753 mM, respectively.

[0078] In step (1), the ionic liquid containing the reactive monomer a is poured or sprayed onto the inert porous membrane, and a negative pressure is applied below to draw the liquid into the pores of the inert porous membrane. The amount of ionic liquid containing the reactive monomer a poured onto the inert porous membrane is 1 mL·cm -2 ; in step (2), the solution containing the reactive monomer b is sprayed onto the surface of the supported liquid membrane at a spraying rate of 0.5 mL·cm -2 ·min -1 . The thin-layer composite ionic liquid supported liquid membranes of Examples 1-4 are prepared.

[0079] The thin-layer composite ionic liquid supported liquid membranes prepared in Examples 1-4 are used for pressure breakthrough testing. The outlet end pressure of the test device is atmospheric pressure, and the inlet end pressure is increased until the thin-layer composite ionic liquid supported liquid membrane is broken down. The pressure difference between the two sides of the thin-layer composite ionic liquid supported liquid membrane at the time of breakdown is the breakthrough pressure. The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] In contrast, under the same conditions, the conventional supported liquid membrane prepared by using polyvinylidene fluoride microfiltration membrane with a pore size of 0.10 μm as an inert porous membrane (without polyamide microporous membrane) has a breakthrough pressure of 100 kPa. Compared with Examples 1-4, it can be seen that the thin-layer composite ionic liquid supported liquid membrane with polyamide microporous membrane effectively improves the breakthrough pressure, and when the thickness of the polyamide microporous membrane reaches 200 nm, the breakthrough pressure no longer further increases significantly.

[0083] The thin-layer composite ionic liquid supported liquid membrane prepared in Examples 1-4 was subjected to CO2 / N2 gas separation test, and the test device had an outlet pressure of 1 bar, an inlet pressure of 2 bar, and a test temperature of 25°C. The test results are shown in Table 2.

[0084] Table 2

[0085]

[0086] In contrast, under the same conditions, the conventional supported liquid membrane prepared by using polyvinylidene fluoride microfiltration membrane with a pore size of 0.10 μm as an inert porous membrane (without polyamide microporous membrane) has a CO2 permeance of 380 barrers and a CO2 / N2 ideal separation ratio of 40. Compared with Examples 1-4, it can be seen that the gas permeation efficiency of the thin-layer composite ionic liquid supported liquid membrane with polyamide microporous membrane is only slightly decreased, while the separation ratio is increased by 50%. And with the increase of the thickness of the polyamide microporous membrane, the carbon dioxide permeance of the thin-layer composite ionic liquid supported liquid membrane decreases.

[0087] The thin-layer composite ionic liquid supported liquid membrane prepared in Example 2 was used for CO2 / N2 gas separation test at a higher pressure, and the test device had an outlet pressure of 1 bar, an inlet pressure of 3 bar or 4 bar, and a test temperature of 25°C. The test results are shown in Table 3.

[0088] Table 3

[0089]

[0090] Table 3 data shows that the thin-layer composite ionic liquid supported liquid membrane can realize stable gas separation at high pressure.

[0091] The thin-layer composite ionic liquid supported liquid membrane prepared in Example 2 was used for long-term CO2 / N2 gas separation test, and the test device had an outlet pressure of 1 bar, an inlet pressure of 2 bar, and a test temperature of 25°C. The test results are shown in Table 4.

[0092] Table 4

[0093]

[0094]

[0095] In contrast, the supported liquid membrane prepared with polyvinylidene fluoride microfiltration membrane with a pore size of 0.10 μm as the inert porous membrane (without polyamide microporous membrane) was completely broken at 36 h of operation. The data in Table 4 show that the thin-layer composite ionic liquid supported liquid membrane can be stably operated for a long time under a certain pressure.

[0096] Examples 5-8

[0097] In Examples 5-8, the inert porous membrane in Example 2 was replaced by polyvinylidene fluoride microfiltration membranes with nominal pore sizes of 0.22 μm, 0.45 μm, 0.80 μm, and 1.2 μm, respectively, and the porosities of the membranes were all 55-50%. The other preparation conditions were unchanged.

[0098] The thin-layer composite ionic liquid supported liquid membranes prepared in Examples 5-7 were used for pressure breakdown tests, and the test conditions were the same as in Examples 1-4. The test results are shown in Table 5.

[0099] Table 5

[0100] Examples Polyvinylidene fluoride microfiltration membrane pore size Breakthrough pressure (kPa) 5 0.22 μm 250 6 0.45 μm 200 7 0.80 μm 180 8 1.2 μm 40

[0101] Examples 5-8 show, in comparison with Example 2, that the increase in the pore size of the inert porous support membrane is not conducive to the increase in the breakdown pressure of the thin-layer composite ionic liquid supported liquid membrane.

[0102] Examples 9-11

[0103] In Examples 9-11, the inert porous membrane in Example 2 was replaced by a 0.22 μm nominal pore size nylon 66 microfiltration membrane, a 0.22 μm nominal pore size polyether sulfone microfiltration membrane, and a 200 nm nominal pore size anodic aluminum membrane, respectively, and the other conditions were the same as in Example 2.

[0104] The thin-layer composite ionic liquid supported liquid membranes prepared in Examples 9-11 were used for tests. The outlet gas pressure in the test device was 1 bar, the inlet gas pressure was 2 bar, and the test temperature was 25°C. The test results are shown in Table 6.

[0105] Table 6

[0106]

[0107] Examples 9-11 show, in comparison with Example 2, that the design of the thin-layer composite ionic liquid supported liquid membrane is universal and is suitable for a variety of inert porous membranes. The increase in the porosity of the inert porous support membrane leads to an increase in the gas permeability of the thin-layer composite ionic liquid supported liquid membrane.

[0108] Examples 12-15

[0109] In Examples 12-15, the 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in Example 2 was replaced by 1-decyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium triflate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, respectively, and other conditions were the same as in Example 2.

[0110] The thin layer composite ionic liquid supported liquid membranes prepared in Examples 12-15 were used for testing. The pressure at the gas outlet end in the testing device was 1 bar, the pressure at the gas inlet end was 2 bar, and the testing temperature was 25°C. The testing results are shown in Table 7.

[0111] Table 7

[0112]

[0113] Examples 12-15 show that the thin layer composite ionic liquid supported liquid membranes are suitable for a variety of ionic liquids, all of which have excellent breakdown pressure and good gas permeability.

[0114] Examples 16-19

[0115] In Examples 16-19, the reactive monomer a tetra(4-aminophenyl)methane in Example 2 was replaced by m-phenylenediamine, piperazine, 9,9'-bis(4-aminophenyl)fluorene, tetra(4-aminophenyl)ethylene, respectively, and other conditions were the same as in Example 2.

[0116] The thin layer composite ionic liquid supported liquid membranes prepared in Examples 16-19 were used for testing. The pressure at the gas outlet end in the testing device was 1 bar, the pressure at the gas inlet end was 2 bar, and the testing temperature was 25°C. The testing results are shown in Table 8.

[0117] Table 8

[0118]

[0119] In contrast, the pore size of the polyamide microporous membrane obtained in Example 2 was 2.2-4.0 nm. The comparison between Example 2 and Examples 16-19 shows that the reduction of the pore size of the polyamide microporous membrane helps to improve the breakdown pressure of the thin layer composite ionic liquid supported liquid membrane, but the gas permeability is reduced. When the pore size of the polyamide microporous membrane is close to the size of the gas molecules, it helps to improve the ideal gas separation ratio of CO2 / N2 of the thin layer composite ionic liquid supported liquid membrane.

[0120] The above-described examples have described the technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, supplement, and equivalent replacement within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A thin layer composite ionic liquid supported liquid membrane characterized in that, The application relates to a thin-layer composite ionic liquid supported liquid membrane, which comprises a nanometer microporous film and an inert porous membrane supporting ionic liquid, and the nanometer microporous film and the inert porous membrane supporting ionic liquid are tightly combined to form a double-layer structure. The nanometer microporous film is a polyamide film with a thickness of 1-10000 nm and a pore size of 0.1-10 nm.

2. The thin-layer composite ionic liquid supported liquid membrane according to claim 1, wherein, The inert porous membrane has a pore size of 0.1-100 mu m.

3. The thin-layer composite ionic liquid supported liquid membrane according to claim 1 or 2, characterized in that, The inert porous membrane is made of at least one of ceramic, metal and polymer.

4. A continuous process for the preparation of thin layer supported liquid membranes of ionic liquids according to any one of claims 1 to 3, characterized in that, The application further discloses a preparation method of the thin-layer composite ionic liquid supported liquid membrane. (1) uniformly coating an ionic liquid solution of reactive monomer a on the inert porous membrane to form a stable and uniform supported liquid membrane, and continuously and smoothly conveying the supported liquid membrane forward through a conveying mechanism; (2) contacting the supported liquid membrane with a solution of reactive monomer b to initiate an interfacial polymerization reaction and synthesize a nanometer microporous film on the surface of the supported liquid membrane; (3) removing the solution of unreacted reactive monomer b on the surface of the nanometer microporous film through washing and drying to obtain the thin-layer composite ionic liquid supported liquid membrane.

5. The continuous process for the preparation of thin layer supported liquid membranes of ionic liquids according to claim 4, characterized in that, In step (1), the coating mode of the ionic liquid solution of reactive monomer a is one or a combination of the following modes: (A) immersing the inert porous membrane in the ionic liquid solution of reactive monomer a; (B) pouring or spraying the ionic liquid solution of reactive monomer a on the inert porous membrane and applying negative pressure under the inert porous membrane to draw the ionic liquid solution of reactive monomer a into the pore channels of the inert porous membrane; (C) pouring or spraying the ionic liquid solution of reactive monomer a on the inert porous membrane and pressing the ionic liquid solution of reactive monomer a into the pore channels of the inert porous membrane by using a roller.

6. The continuous process for the preparation of thin layer supported liquid membranes of ionic liquids according to claim 4, characterized in that, In step (2), the contacting mode of the supported liquid membrane with the solution of reactive monomer b is one or a combination of the following modes: (D) immersing the supported liquid membrane in the solution of reactive monomer b; (E) spraying the solution of reactive monomer b on the surface of the supported liquid membrane.

7. The continuous process for the preparation of thin layer supported liquid membranes of ionic liquids according to claim 4, characterized in that, The reactive monomer a is an amine compound and the reactive monomer b is an acyl chloride compound.

8. The continuous process for the preparation of thin layer supported liquid membranes of ionic liquids according to claim 7, characterized in that, In the ionic liquid solution of reactive monomer a, the concentration of the reactive monomer a is 1-1000 mM; and in the solution of reactive monomer b, the concentration of the reactive monomer b is 0.01-300 mM.

9. Application of the thin-layer composite ionic liquid supported liquid membrane in gas separation.

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