阅读说明：本技术 气体分离膜、气体分离膜元件、气体分离装置和气体分离方法 (Gas separation membrane, gas separation membrane element, gas separation device, and gas separation method ) 是由 高桥里奈 佐藤一树 小岩雅和 佐佐木崇夫 于 2018-05-31 设计创作，主要内容包括：本发明涉及气体分离膜,其具有：多孔性支撑层、和设置在前述多孔性支撑层上且含有通过多官能性芳香族胺与多官能性芳香族酰卤的缩聚而得的交联芳香族聚酰胺的分离功能层；前述交联芳香族聚酰胺具有键合于芳香族环的氟原子和键合于氮原子的氟原子中的至少一者。(The present invention relates to a gas separation membrane having: a porous support layer and a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide; the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.)

1. A gas separation membrane having:

a porous support layer, and

a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide;

the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

2. The gas separation membrane according to claim 1, wherein a ratio of the number of fluorine atoms to the number of carbon atoms is in a range of 0.001 to 0.12 when the crosslinked aromatic polyamide is analyzed by X-ray photoelectron spectroscopy (XPS).

3. The gas separation membrane according to claim 1 or 2, wherein a ratio of the number of fluorine atoms to the number of carbon atoms is in a range of 0.001 to 0.080 when the crosslinked aromatic polyamide is analyzed by X-ray photoelectron spectroscopy (XPS).

4. A gas separation membrane element having:

a gas collecting pipe for collecting the permeating gas,

A supply-side flow path material,

A permeation side flow path material, and

a gas separation membrane according to any one of claims 1 to 3;

wherein the content of the first and second substances,

the gas separation membrane is disposed between the supply-side flow path material and the permeation-side flow path material such that a surface of a separation functional layer included in the gas separation membrane faces the permeation-side flow path material,

the gas separation membrane, the supply-side flow path material, and the permeate-side flow path material are spirally wound around the gas header.

5. A gas separation device having the gas separation membrane according to any one of claims 1 to 3.

6. A gas separation process comprising the steps of:

(1) a step of supplying a mixed gas containing carbon dioxide to one surface of a gas separation membrane, and

(2) obtaining a gas having a carbon dioxide concentration lower than that of the mixed gas from the other surface of the gas separation membrane;

wherein the content of the first and second substances,

the gas separation membrane has:

a porous support layer, and

a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide;

the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

7. A gas separation process comprising the steps of:

(1) a step of supplying a mixed gas containing nitrogen to one surface of the gas separation membrane, and

(2) obtaining a gas having a nitrogen concentration lower than that of the mixed gas from the other surface of the gas separation membrane;

wherein the content of the first and second substances,

the gas separation membrane has:

a porous support layer, and

a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide;

the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

8. The gas separation method according to claim 6 or 7, wherein the mixed gas contains at least one of hydrogen and helium.

Technical Field

The present invention relates to a gas separation membrane, a gas separation membrane element, a gas separation apparatus, and a gas separation method using the same, in which a light gas such as helium or hydrogen is separated from carbon dioxide using a polyamide composite membrane.

Background

In recent years, hydrogen has attracted attention as a clean energy source. Hydrogen is obtained by gasifying fossil fuels such as natural gas and coal and removing carbon dioxide from a mixed gas containing hydrogen and carbon dioxide as main components. The gas to be treated is characterized by high temperature and high pressure by steam reforming and water gas shift reaction.

As a method of concentrating a specific gas from a mixed gas at low cost, a membrane separation method of selectively transmitting a target gas by utilizing a difference in gas permeability of a raw material has been attracting attention.

For example, non-patent document 1 proposes a gas separation membrane that can obtain high air permeability because a crosslinkable aromatic polyamide is formed by an interfacial polycondensation reaction to form an extremely thin functional layer.

Disclosure of Invention

Technical problem to be solved by the invention

However, the crosslinkable aromatic polyamides known so far have problems that the separation selectivity of hydrogen and carbon dioxide is low and the efficiency of removing carbon dioxide from a mixed gas containing hydrogen and carbon dioxide is poor because of low solubility of hydrogen.

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide a gas separation membrane, a gas separation membrane element, a gas separation apparatus, and a gas separation method that have both permeability and separation selectivity for light gases such as hydrogen and helium.

Means for solving the problems

In order to solve the above problems, the following configuration is adopted.

[1] A gas separation membrane having: a porous support layer and a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide;

the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

[2] The gas separation membrane according to [ 1], wherein when the crosslinked aromatic polyamide is analyzed by X-ray photoelectron spectroscopy (XPS), a ratio of the number of fluorine atoms to the number of carbon atoms is in a range of 0.001 to 0.12.

[3] The gas separation membrane according to [ 1] or [ 2], wherein when the crosslinked aromatic polyamide is analyzed by X-ray photoelectron spectroscopy (XPS), a ratio of the number of fluorine atoms to the number of carbon atoms is in a range of 0.001 to 0.080.

[4] A gas separation membrane element having: a gas header for collecting a permeated gas, a supply-side channel material, a permeation-side channel material, and the gas separation membrane according to any one of [ 1] to [ 3 ];

wherein the gas separation membrane is disposed between the supply-side flow path material and the permeation-side flow path material such that a surface of a separation functional layer of the gas separation membrane faces the permeation-side flow path material,

the gas separation membrane, the supply-side channel member, and the permeate-side channel member are spirally wound around the gas header.

[5] A gas separation device having the gas separation membrane according to any one of [ 1] to [ 3 ].

[6] A gas separation process comprising the steps of:

(1) a step of supplying a mixed gas containing carbon dioxide to one surface of a gas separation membrane, and

(2) obtaining a gas having a carbon dioxide concentration lower than that of the mixed gas from the other surface of the gas separation membrane;

wherein the gas separation membrane has: a porous support layer and a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide;

the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

[7] A gas separation process comprising the steps of:

(1) a step of supplying a mixed gas containing nitrogen to one surface of the gas separation membrane, and

(2) obtaining a gas having a nitrogen concentration lower than that of the mixed gas from the other surface of the gas separation membrane;

wherein the gas separation membrane has: a porous support layer and a separation functional layer provided on the porous support layer and containing a crosslinked aromatic polyamide obtained by polycondensation of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide;

the crosslinked aromatic polyamide has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

[8] The gas separation method according to [ 6 ] or [ 7 ], wherein the mixed gas contains at least one of hydrogen and helium.

Effects of the invention

According to the present invention, a gas separation membrane element, a gas separation apparatus, and a gas separation method using the same, which have high gas permeability and separation selectivity with practical utility, can be provided.

Drawings

FIG. 1: fig. 1 is a partially exploded perspective view showing an embodiment of a gas separation membrane element according to the present invention.

FIG. 2: FIG. 2 is a schematic view of an apparatus used in examples for measuring the gas permeability of a gas separation membrane.

FIG. 3: fig. 3 is a schematic view of an apparatus used in the examples for applying pressure to the gas separation membrane.

Detailed Description

1. Gas separation membrane

The gas separation membrane includes at least a porous support layer and a separation function layer, and in the present embodiment, the gas separation membrane includes: the separation device comprises a substrate, a porous supporting layer on the substrate and a separation function layer on the porous supporting layer. The substrate and the porous support layer have substantially no gas separation performance and serve as a support (support membrane) for supporting the separation function layer.

(1-1) base Material

Examples of the base material include polyester polymers, polyamide polymers, polyolefin polymers, and mixtures and copolymers thereof. Among them, a fabric of a polyester polymer having high mechanical stability and thermal stability is particularly preferable. As the form of the fabric, a long fiber nonwoven fabric or a short fiber nonwoven fabric can be preferably used, and a knitted fabric is more preferably used. The long fiber nonwoven fabric is a nonwoven fabric having an average fiber length of 300mm or more and an average fiber diameter of 3 to 30 μm.

The substrate preferably has an air flow of 0.5cc/cm²5.0cc/cm and a sec or more²And/sec or less. When the air flow rate of the substrate is in the above range, the polymer solution forming the porous support layer is impregnated into the substrate, and therefore, the adhesiveness between the porous support layer and the substrate is improved, and the physical stability of the support membrane can be improved.

The thickness of the base material is preferably within a range of 10 to 200 μm, more preferably within a range of 30 to 120 μm.

In the present specification, unless otherwise specified, the thickness means an average value. Here, the average means an arithmetic average.

That is, the thickness of the substrate and the thickness of the porous support layer described later can be determined by calculating the average value of the thicknesses at 20 points measured at 20 μm intervals in the direction (the plane direction of the film) orthogonal to the thickness direction in the cross-sectional view.

(1-2) porous support layer

The porous support layer does not substantially have a gas separation performance, and is used to impart strength to the separation function layer having a gas separation performance substantially.

The pore diameter and pore distribution of the porous support layer are not particularly limited. For example, the pore diameter may be uniform over the entire porous support layer, or may gradually increase from the surface on the side where the separation function layer is formed to the other surface. In addition, in the porous support layer, the pore diameter of the surface on the side where the separation function layer is formed is preferably 0.1nm or more and 100nm or less.

The porous support layer contains at least 1 polymer selected from homopolymers and copolymers of, for example, polysulfone, polyethersulfone, polyamide, polyester, cellulosic polymers, vinyl polymers, polyphenylene sulfide sulfone, polyphenylene ether, and the like.

Here, cellulose polymers include cellulose acetate and cellulose nitrate, and vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile.

The porous support layer preferably contains a homopolymer or copolymer of polysulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide sulfone, polyphenylene sulfone, or the like.

The porous support layer more preferably contains cellulose acetate, polysulfone, polyphenylene sulfide sulfone, or polyphenylene sulfone. Among these materials, polysulfone is particularly preferable in view of high chemical stability, mechanical stability, and thermal stability and easiness of molding.

Specifically, the porous support layer preferably contains polysulfone formed of a repeating unit represented by the following chemical formula. In the porous support layer containing polysulfone, the pore diameter is easily controlled, and the dimensional stability of the porous support layer is high. In the following formula, n means the number of repetitions.

[ solution 1]

The weight average molecular weight (Mw) of polysulfone measured by Gel Permeation Chromatography (GPC) using N-methylpyrrolidone as a solvent and polystyrene as a standard substance is preferably 10000 or more and 200000 or less, more preferably 15000 or more and 100000 or less. When the Mw of polysulfone is 10000 or more, the mechanical strength and heat resistance preferable as the porous support layer can be obtained. Further, when the Mw of polysulfone is 200000 or less, the viscosity of the solution is in an appropriate range, and good moldability can be achieved.

The porous support layer preferably contains the above-mentioned polymer as a main component. Specifically, the ratio of the polymer in the porous support layer (the total ratio of the polymers when a plurality of polymers are contained) is preferably 70% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, and most preferably the porous support layer is composed only of the polymer.

The thickness of the substrate and porous support layer can have an effect on the mechanical strength of the gas separation membrane and the packing density of the gas separation membrane when fabricated into a component. In order to obtain sufficient mechanical strength and packing density, the total thickness of the base material and the porous support layer is preferably 30 μm or more and 300 μm or less, and more preferably 100 μm or more and 220 μm or less.

The thickness of the porous support layer is preferably 20 μm or more and 100 μm or less.

The porous support layer used in the present invention may be selected from various commercially available materials such as "ミ リ ポ ア フ ィ ル タ ー VSWP" (trade name) manufactured by ミ リ ポ ア corporation and "ウ ル ト ラ フ ィ ル タ ー UK 10" (trade name) manufactured by eastern filter paper plant, or may be manufactured according to the method described in "オ フ ィ ス, seed オ ブ, seed セ イ リ ー ン, seed ウ ォ ー タ ー, seed リ サ ー チ, seed ア ン ド, seed デ ィ ベ ロ ッ プ メ ン ト, seed プ ロ グ レ ス, seed レ ポ ー ト" No.359 (1968).

(1-3) separating functional layer

The separating functional layer contains a crosslinked aromatic polyamide (hereinafter, may be simply referred to as "polyamide") obtained by polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide.

In other words, the separating functional layer contains a crosslinked aromatic polyamide having a moiety derived from a polyfunctional aromatic amine and a moiety derived from a polyfunctional aromatic acid halide. The "moiety derived from the polyfunctional aromatic amine" refers to a moiety obtained by removing a functional group contributing to bonding in polycondensation from the polyfunctional aromatic amine. The "moiety derived from polyfunctional aromatic acid halide" also refers to a moiety obtained by removing a functional group contributing to bonding in polycondensation from polyfunctional aromatic acid halide.

The polycondensation reaction means interfacial polycondensation.

Here, "polyfunctional aromatic amine" means an aromatic amine having 2 or more amino groups in one molecule, and at least one of the amino groups is a primary amino group.

Examples of the polyfunctional aromatic amine include polyfunctional aromatic amines in which 2 amino groups such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, o-diaminopyridine, m-diaminopyridine, and p-diaminopyridine are bonded to an aromatic ring in any of the ortho-position, meta-position, and para-position relationships; 1,3, 5-triaminobenzene, 1,2, 4-triaminobenzene, 3, 5-diaminobenzoic acid, 3-aminobenzylamine, 4-aminobenzylamine, 2, 4-diaminothioanisole, 1, 3-diamino-5- (dimethylphosphino) benzene, (3, 5-diaminophenyl) dimethylphosphine oxide, (2, 4-diaminophenyl) dimethylphosphine oxide, 1, 3-diamino-5- (methylsulfonyl) benzene, 1, 3-diamino-4- (methylsulfonyl) benzene, 1, 3-diamino-5-nitrosobenzene, 1, 3-diamino-4-nitrosobenzene, 1, 3-diamino-5- (hydroxyamino) benzene, and mixtures thereof, And polyfunctional aromatic amines such as 1, 3-diamino-4- (hydroxyamino) benzene.

Among them, in view of the separation selectivity, permeability, and heat resistance of the membrane, the polyfunctional aromatic amine is preferably an aromatic amine having 2 to 4 amino groups in one molecule and at least one of the amino groups is a primary amino group, and m-phenylenediamine, p-phenylenediamine, and 1,3, 5-triaminobenzene can be suitably used. Among them, m-phenylenediamine is more preferably used from the viewpoint of ease of obtaining and simplicity of operation. These polyfunctional aromatic amines may be used alone or in combination of 2 or more.

Further, "polyfunctional aromatic acid halide" also means a polyfunctional aromatic carboxylic acid derivative, and means an aromatic acid halide having at least 2 halogenated carbonyl groups in one molecule.

Examples of the polyfunctional aromatic acid halide include 3-functional acid halides such as trimesoyl chloride, and 2-functional acid halides such as biphenyldicarbonyl chloride, azobenzenedicarbonyl chloride, terephthaloyl chloride, isophthaloyl chloride, and naphthalenedicarbonyl chloride.

In view of reactivity with the polyfunctional aromatic amine, the polyfunctional aromatic acid halide is preferably a polyfunctional aromatic acid chloride. In addition, in view of the separation selectivity and heat resistance of the membrane, the polyfunctional aromatic acid halide is preferably a polyfunctional aromatic acid chloride having 2 to 4 chloroformyl groups in one molecule. Among them, trimesoyl chloride is more preferably used from the viewpoint of ease of obtaining and ease of operation. These polyfunctional aromatic acid halides may be used alone or in combination of 2 or more.

Further, it is preferable that at least one of the polyfunctional aromatic amine and the polyfunctional aromatic acid halide contains a compound having 3 or more functions.

The separation functional layer preferably contains, as a main component, the crosslinked aromatic polyamide obtained by the polycondensation reaction of the polyfunctional aromatic amine and the polyfunctional aromatic acid halide. Specifically, the content of the crosslinked aromatic polyamide in the separating functional layer is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more, and the separating functional layer may be composed of only the crosslinked aromatic polyamide. When the separation functional layer contains 50 wt% or more of the crosslinked aromatic polyamide, high-performance film performance is easily exhibited.

In order to obtain sufficient gas separation performance and gas permeability, the thickness of the separation functional layer is usually in the range of 0.01 to 1 μm, preferably in the range of 0.1 to 0.5 μm.

The crosslinked aromatic polyamide used in the present invention has at least one of a fluorine atom bonded to an aromatic ring and a fluorine atom bonded to a nitrogen atom.

The fluorine atom-bonded aromatic ring may be derived from an aromatic amine or acid halide in the polyamide-forming monomers.

Fluorine has a high affinity for light gases such as hydrogen and helium. Therefore, the solubility of the light gas in the polyamide is improved by the presence of the fluorine atom on at least one of the aromatic ring and the nitrogen atom of the polyamide. In addition, the introduced fluorine atoms form a steric barrier to prevent the permeation of carbon dioxide and nitrogen, which have larger molecular diameters than the light gas, and thus the separation selectivity of the light gas, carbon dioxide and nitrogen is improved.

In addition, from the viewpoint of satisfying both the permeability of light gases and the separation selectivity, when the crosslinked aromatic polyamide is analyzed by X-ray photoelectron spectroscopy (XPS), the ratio of the number of fluorine atoms to the number of carbon atoms (the number of fluorine atoms/the number of carbon atoms) is preferably in the range of 0.001 to 0.12, and more preferably in the range of 0.001 to 0.080.

When the ratio is 0.001 or more, the polyamide is reduced in the flocculation property and the separation selectivity is improved. In addition, when the ratio is 0.12 or less, defects are less likely to occur even when the gas separation membrane is pressurized. Further, when the above ratio is 0.080 or less, the performance of the gas separation membrane can be kept constant even when the gas separation membrane is pressurized.

As X-ray photoelectron spectroscopy (XPS), X-ray photoelectron spectroscopy (XPS) exemplified in Journal of Polymer Science, Vol.26,559-572 (1988) and J.J.Japan society of adhesion, Vol.27, No.4 (1991) can be used.

As described later, the crosslinked aromatic polyamide may have a moiety derived from a monofunctional aromatic acid halide. The "moiety derived from a monofunctional aromatic acid halide" means a moiety from which a functional group contributing to bonding in polycondensation is removed from a monofunctional aromatic acid halide.

2. Method for producing gas separation membrane

Next, a method for producing the gas separation membrane will be described.

(2-1) formation of support film

In this embodiment, first, a support film is formed, the support film including a laminate of a substrate and a porous support layer.

The method of forming the support film includes, for example: the method includes a step 1 of preparing a polymer solution by dissolving a polymer, which is a constituent component of the porous support layer, in a good solvent for the polymer, a step 2 of applying the polymer solution to the substrate, and a step 3 of immersing the polymer solution in a coagulation bath to wet-coagulate the polymer.

Examples of the good solvent used in step 1 include N-methyl-2-pyrrolidone (NMP); tetrahydrofuran; dimethyl sulfoxide; amides such as tetramethylurea, N-dimethylacetamide, and N, N-dimethylformamide (hereinafter referred to as DMF); lower alkyl ketones such as acetone and methyl ethyl ketone; esters and lactones such as trimethyl phosphate and γ -butyrolactone; and mixed solvents thereof, and the like.

When polysulfone is used for the porous support layer in step 1, a polymer solution is obtained by dissolving polysulfone in DMF.

The concentration of the polymer in the polymer solution in step 1 is preferably 10 to 25 wt%, and more preferably 13 to 22 wt%. When the concentration of the polymer is 10% by weight or more, the viscosity of the polymer solution is high, and the thickness of the porous support layer can be controlled to a desired thickness. When the concentration of the polymer is 25 wt% or less, the ratio of the dense layer of the porous support layer is small, and an aqueous solution of the polyfunctional aromatic amine can be held in a necessary amount when producing the separation functional layer.

In step 2, various coating methods can be used as a method for coating the polymer solution on the substrate, and a pre-metered coating method such as die coating, slide coating, curtain coating, or the like, which can supply an accurate amount of the polymer solution, can be preferably used.

In step 3, the polymer solution is immersed in a coagulation bath to wet-coagulate the polymer, and water can be preferably used as the coagulation bath. The temperature of the coagulation bath is preferably 5 to 50 ℃, and more preferably 10 to 30 ℃. When the temperature is 5 ℃ or higher, a sufficient solidification rate can be obtained and film forming properties are good. When the temperature is 50 ℃ or lower, vibration of the coagulation bath surface due to thermal motion does not become severe, and the smoothness of the film surface after formation is good. The time for immersing the polymer solution in the coagulation bath is preferably 3 seconds to 30 minutes, and more preferably 5 seconds to 20 minutes, from the viewpoint of the coagulation rate.

(2-2) method for producing separating functional layer

Next, a step of forming a separation function layer constituting the gas separation membrane will be described. The step of forming the separating function layer includes:

(a) a step of contacting an aqueous solution containing a polyfunctional aromatic amine on a porous support layer of a support film, and

(b) a step of contacting an organic solvent solution containing a polyfunctional aromatic acid halide on a porous support layer contacted with an aqueous solution containing a polyfunctional aromatic amine.

Further, the step of forming the separation function layer satisfies at least one of the following conditions:

as a seed, in the above (a), the above aqueous solution contains a polyfunctional aromatic amine having a fluorine atom bonded to an aromatic ring (condition 1),

As a seed, in the above (b), the above organic solvent solution contains a monofunctional or polyfunctional acid aromatic acyl halide having a fluorine atom bonded to an aromatic ring (condition 2),

Seeding after the above (b), a treatment for introducing a fluorine atom into at least one of an aromatic ring and a nitrogen atom contained in the polyamide is performed (condition 3).

Specific examples of the polyfunctional aromatic amine having a fluorine atom bonded to an aromatic ring include 1, 3-diaminotetrafluorobenzene, 1, 4-diamino-2-fluorobenzene, 2,3,5, 6-tetrafluoro-1, 4-phenylenediamine, 2,4, 5-trifluoro-1, 4-phenylenediamine, and 2, 5-difluoro-1, 4-phenylenediamine.

Specific examples of the monofunctional or polyfunctional acid aromatic acid halide having a fluorine atom bonded to an aromatic ring include o-fluorobenzoyl chloride, p-fluorobenzoyl chloride, m-fluorobenzoyl chloride, pentafluorobenzoyl chloride, 3, 5-difluorobenzoyl chloride, 2,4, 6-trifluorobenzoyl chloride, tetrafluoroisophthaloyl chloride, and tetrafluoroterephthaloyl chloride.

Hereinafter, the steps will be described in order.

In step (a), the concentration of the polyfunctional aromatic amine in the polyfunctional aromatic amine-containing aqueous solution (hereinafter, sometimes referred to as "polyfunctional aromatic amine aqueous solution") is preferably in the range of 0.1% by weight or more and 20% by weight or less, and more preferably in the range of 0.5% by weight or more and 15% by weight or less. When the concentration of the polyfunctional aromatic amine is in this range, sufficient solute removal performance and water permeability can be obtained.

The aqueous polyfunctional aromatic amine solution may further contain a surfactant, an organic solvent, a basic compound, an antioxidant, and the like, as long as the reaction between the polyfunctional aromatic amine and the polyfunctional aromatic acid halide is not hindered. The surfactant has the effects of improving the wettability of the surface of the support film and reducing the surface tension between the aqueous polyfunctional aromatic amine solution and the nonpolar solvent. The organic solvent can function as a catalyst for the interfacial polycondensation reaction, and can be added to efficiently perform the interfacial polycondensation reaction.

The contact between the aqueous polyfunctional aromatic amine solution and the support film is preferably performed uniformly and continuously on the porous support layer of the support film. Specifically, for example, a method of applying the polyfunctional aromatic amine aqueous solution to the porous support layer of the support film, or a method of immersing the porous support layer of the support film in the polyfunctional aromatic amine aqueous solution may be mentioned. The contact time between the porous support layer of the support film and the aqueous polyfunctional aromatic amine solution is preferably 1 second to 10 minutes, and more preferably 10 seconds to 3 minutes.

After contacting the aqueous polyfunctional aromatic amine solution with the porous support layer of the support film, the solution is removed sufficiently to prevent droplets from remaining on the film. By sufficiently removing the liquid, it is possible to prevent the residual portion of the liquid droplets from forming a film defect and degrading the film performance after the separation function layer is formed. As a method for removing the liquid, for example, as described in japanese patent laid-open No. 2-78428, a method of naturally flowing an excessive amount of the aqueous solution with a support film in contact with the aqueous solution of the polyfunctional aromatic amine held in a vertical direction, a method of forcibly removing the liquid by blowing an air stream of nitrogen or the like from an air nozzle, or the like can be used. Further, the membrane surface may be dried after the liquid removal to remove the water portion of the aqueous solution.

In the step (b), the concentration of the polyfunctional aromatic acid halide in the organic solvent solution is preferably in the range of 0.01 wt% to 10 wt%, and more preferably in the range of 0.02 wt% to 2.0 wt%. This is because a sufficient reaction rate can be obtained by setting the content to 0.01 wt% or more, and the occurrence of side reactions can be suppressed by setting the content to 10 wt% or less. Further, when an acylation catalyst such as DMF is contained in the organic solvent solution, interfacial polycondensation is promoted, which is more preferable.

When the organic solvent solution contains a monofunctional acid aromatic acid halide having a fluorine atom bonded to an aromatic ring, the concentration of the monofunctional aromatic acid halide in the organic solvent solution is preferably in the range of 0.005 wt% to 1 wt%, and more preferably in the range of 0.01 wt% to 0.2 wt%.

The organic solvent in the organic solvent solution is preferably immiscible with water, and the polyfunctional aromatic acid halide is not dissolved to destroy the support film, and may be inert to the polyfunctional aromatic amine compound and the polyfunctional aromatic acid halide. Preferable examples thereof include hydrocarbon compounds such as n-hexane, n-octane, n-decane and isooctane.

The method of contacting the organic solvent solution containing the polyfunctional aromatic acid halide with the porous support layer in contact with the aqueous polyfunctional aromatic amine compound solution can be performed in the same manner as the method of contacting the aqueous polyfunctional aromatic amine solution with the porous support layer.

In this case, the porous support layer in contact with the organic solvent solution containing the polyfunctional aromatic acid halide may be heated. The heating temperature is 50 ℃ to 180 ℃, preferably 60 ℃ to 160 ℃. By heating at 60 ℃ or higher, the decrease in reactivity accompanying the consumption of the monomer in the interfacial polymerization reaction can be compensated by the effect of promoting the reaction by heat. By heating at 160 ℃ or lower, complete volatilization of the solvent can be prevented and the reaction efficiency can be prevented from being significantly reduced.

The heating time is preferably 5 seconds to 180 seconds. By setting the time to 5 seconds or more, the effect of promoting the reaction can be obtained, and by setting the time to 180 seconds or less, the solvent can be prevented from completely volatilizing.

When at least one of the above conditions 1 and 2 is satisfied, the separation functional layer used in the present invention can be obtained. Further, when neither of the above conditions 1 and 2 is satisfied, at least one of the aromatic ring and the nitrogen atom contained in the obtained polyamide may be chemically treated to introduce a fluorine atom.

Specifically, a fluorinating agent is preferably brought into contact with a gas separation membrane having polyamide, and examples of the fluorinating agent include 1-chloromethyl-4-fluoro-1, 4-diazabicyclo [ 2.2.2 ] octane bis (tetrafluoroborate) (Selectfluor (registered trademark)), N-fluorobenzenesulfonylimide, 1-fluoropyridinium tetrafluoroborate, and the like.

The reaction mode of the fluorinating agent and the polyamide is not particularly limited, and for example, a method of immersing a gas separation membrane having polyamide in an aqueous solution containing a fluorinating agent (hereinafter, sometimes referred to as "aqueous fluorinating agent solution") is preferable.

The concentration of the fluorinating agent in the aqueous solution of the fluorinating agent is preferably 0.01 to 10% by weight, more preferably 0.1 to 1% by weight.

As a chemical treatment method, it is preferable to treat the aqueous solution of the fluorinating agent at 10 ℃ to 100 ℃, more preferably 20 ℃ to 80 ℃. The reaction efficiency can be improved by setting the temperature to 10 ℃ or higher, and the decomposition of the fluorinating agent can be suppressed by setting the temperature to 100 ℃ or lower.

The contact time between the aqueous solution of the fluorinating agent and the gas separation membrane comprising polyamide is preferably 30 seconds to 1 day, and more preferably 1 minute to 30 minutes in view of both the practicability and the reaction efficiency.

The presence of the fluorine atom can be determined by subjecting the polyamide to X-ray photoelectron spectroscopy (XPS) analysis. Specifically, it can be determined by using X-ray photoelectron spectroscopy (XPS) exemplified in "Journal of Polymer Science", Vol.26,559-572 (1988) and "Journal of the Japan society of adhesion", Vol.27, No.4 (1991).

The XPS-derived 1s peak of the fluorine atom is derived from the inner shell electron of the fluorine atom. Since a peak derived from C — F was observed at 686eV, the presence or absence of a fluorine group introduced into at least one of an aromatic ring and a nitrogen atom contained in the polyamide can be analyzed by the presence or absence of the peak.

As described above, a gas separation membrane can be obtained by forming a separation function layer on a support membrane having a porous support layer.

The gas separation membrane thus obtained is preferably dried. The drying method is not particularly limited, and water may be removed by vacuum drying, freeze drying, or heating at high temperature, or the solvent may be removed by immersing in an alcohol solvent such as ethanol or isopropanol or a hydrocarbon solvent to replace water with the solvent and then drying under the above-mentioned drying conditions.

Among these, high-temperature heating which can easily obtain a dense separation functional layer is particularly preferable. The method of high-temperature heating is not particularly limited, and it is preferable to heat the mixture in an oven at 30 to 200 ℃, more preferably 50 to 150 ℃ for 1 minute or more. The removal of moisture can be efficiently performed by setting the temperature to 30 ℃ or higher, and the deformation due to the difference in thermal shrinkage rate between the separation functional layer and the substrate can be prevented by setting the temperature to 200 ℃ or lower.

3. Gas separation membrane element

(3-1) overview

The gas separation membrane element of the present invention comprises: a gas collecting pipe for collecting the permeated gas, a supply-side flow path material, a permeation-side flow path material, and a gas separation membrane of the present invention.

Fig. 1 is an explanatory view showing an embodiment of a gas separation membrane element according to the present invention, and showing a gas separation membrane element 1 partially exploded.

As shown in fig. 1, a gas separation membrane element 1 includes a gas header 2, a gas separation membrane 3, a supply-side channel material 4, and a permeation-side channel material 6. The gas separation membrane 3, the supply-side flow path material 4, and the permeation-side flow path material 6 are spirally wound around the gas header 2.

The gas separation membrane 3 is wound around the gas header 2, and is arranged such that the width direction of the gas separation membrane 3 is along the longitudinal direction of the gas header 2. As a result, the gas separation membrane 3 is arranged such that the longitudinal direction thereof is along the winding direction.

In the present specification, the "inner end in the winding direction" corresponds to an end of the gas separation membrane 3 close to the gas header 2.

(3-2) gas collecting tube

The header 2 is an example of a center pipe that collects the permeated gas 11. The gas collecting pipe 2 may be configured so that the permeated gas 11 flows therethrough, and the material, shape, size, and the like are not particularly limited, but a material made of a metal such as SUS (Stainless Steel scrap), aluminum, copper, brass, titanium, or the like can be suitably Used as the material from the viewpoint of pressure resistance and heat resistance. As the shape, for example, a cylindrical member having a side surface provided with a plurality of holes can be used.

(3-3) gas separation Membrane

A plurality of gas separation membranes 3 are wound around the gas collecting pipe 2. The gas separation membrane 3 is disposed between the supply-side flow path material 4 and the permeation-side flow path material 6 such that the surface of the separation function layer of the gas separation membrane 3 faces the permeation-side flow path material 6.

Specifically, the gas separation membrane 3 is folded so that the supply-side surfaces face each other. By overlapping the other gas separation membrane 3 folded in this way on the gas separation membrane 3 folded in this way, the surface on the transmission side of one gas separation membrane 3 and the surface on the transmission side of the other gas separation membrane 3 are arranged so as to face each other.

In the overlapped gas separation membranes 3, 3 sides except for the inner end in the winding direction are sealed between the surfaces on the permeation side. The gas separation membrane 3 bonded between the surfaces on the transmission side in this manner is referred to as a cylindrical membrane, and is given a reference numeral "5".

The cylindrical membranes 5 are 2-sheet 1-group gas separation membrane pairs in which transmission-side surfaces facing each other are arranged to face each other. The tubular membrane 5 has a rectangular shape, and the space between the surfaces on the permeation side is open only on the inner side in the winding direction in the rectangular shape of the gas separation membrane 3, and the other three sides are sealed so that the permeated gas 11 flows into the gas header 2. The permeated gas 11 is separated from the supplied gas 9 by the cylindrical membrane 5.

Examples of the sealing include a form of bonding with an adhesive or hot melt, a form of welding with heat or laser, and a form of sandwiching a rubber sheet. Sealing by adhesion is particularly preferred because of its simplicity and high effectiveness.

Further, in the above-described example, in the face on the supply side of the gas separation membrane, the inner end in the winding direction is closed by folding, but this portion may be sealed not by folding but by bonding, welding, or the like. By sealing the supply side of the gas separation membrane instead of folding, deflection does not easily occur at the end of the gas separation membrane. By suppressing the occurrence of flexure in the vicinity of the fold, the occurrence of a gap between the gas separation membranes and the occurrence of leakage due to the gap after winding are suppressed.

The gas separation membranes stacked may have the same configuration or different configurations.

The gas separation membranes whose permeation side surfaces or supply side surfaces face each other may be 2 different gas separation membranes or may be formed by folding 1 gas separation membrane.

The permeation-side channel material 6 is disposed inside the tubular membrane 5. Further, the supply-side channel member 4 is disposed between the adjacent 2 cylindrical membranes 5.

(3-4) permeation side flow path Material

The gas separation membrane element 1 is provided with a permeation-side channel material 6.

As the permeation-side channel material 6, those having a mesh shape can be suitably used. The material of the permeate-side channel member 6 is not particularly limited, and a metal such as SUS, aluminum, copper, brass, or titanium may be selected, polyurethane resins, epoxy resins, polyether sulfones, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyphenylene sulfide, polystyrene, styrene-acrylonitrile copolymers, styrene-butadiene-acrylonitrile copolymers, polyacetal, polymethyl methacrylate, methacrylic acid-styrene copolymers, cellulose acetate, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, fluorine resins (chlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkoxyethylene copolymers, tetrafluoroethylene-ethylene copolymers, etc.), and the like. These materials may be used alone or as a mixture of 2 or more. The permeation-side flow path material 6 forms a permeation-side flow path inside the closed-tubular membrane, that is, between the permeation-side surfaces of the gas separation membranes facing each other.

(3-5) supply-side flow path Material

As shown in fig. 1, the gas separation membrane element 1 includes a supply-side flow channel material 4 between supply-side surfaces of the gas separation membranes 3 facing each other.

The supply-side flow path material 4 may be any material that can ensure a space between the gas separation membranes 3 through which the mixed gas can pass while contacting the gas separation membranes 3.

The height (thickness) of the supply-side flow path material 4 is preferably more than 0.5mm and 2.0mm or less, and more preferably 0.6mm or more and 1.0mm or less, in consideration of balance between the respective performances and the operation cost.

The shape of the supply-side channel member 4 is not particularly limited, and examples thereof include members such as a film and a net. The material of the supply-side flow path material 4 is not particularly limited, and a metal such as SUS, aluminum, copper, brass, or titanium may be selected, polyurethane resins, epoxy resins, polyether sulfones, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyphenylene sulfide, polystyrene, styrene-acrylonitrile copolymers, styrene-butadiene-acrylonitrile copolymers, polyacetal, polymethyl methacrylate, methacrylic acid-styrene copolymers, cellulose acetate, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, fluorine resins (chlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkoxyethylene copolymers, tetrafluoroethylene-ethylene copolymers, etc.), and the like. These materials may be used alone or as a mixture of 2 or more. Further, the material of the supply-side flow path material 4 may be the same as or different from that of the gas separation membrane 3.

(3-6) other constituent elements

The gas separation membrane element 1 has the following structure in addition to the above structure.

That is, the gas separation membrane element 1 has perforated end plates 7 at both ends (i.e., the 1 st end and the 2 nd end) thereof, and the perforated end plates 7 have a plurality of holes through which the supply gas 9 can pass. In the gas separation membrane element 1, an outer package 8 is wound around the outer peripheral surface of the wound separation membrane (hereinafter referred to as a "wound body").

4. Gas separation device

The gas separation membrane and the gas separation membrane element of the present invention can be applied to a gas separation apparatus capable of separating and purifying a gas. That is, the gas separation apparatus of the present invention includes the gas separation membrane and the gas separation membrane element of the present invention.

The gas separation device of the present invention comprises: a mixed gas supply unit that feeds the mixed gas to the supply side of the gas separation membrane element, a recovery unit that recovers the gas (that has permeated the separation membrane) separated from the mixed gas by the gas separation membrane element from the permeation side of the gas separation membrane element, a discharge unit that discharges the gas that has not permeated from the supply side of the gas separation membrane element to the outside of the gas separation apparatus, and the like.

The gas separation apparatus of the present invention may further include a purge gas supply unit for supplying a purge gas to the permeate side of the gas separation membrane element, in addition to the above.

More specifically, the gas separation device of the present invention may comprise: a housing for housing the gas separation membrane element, piping, a vacuum pump, a compressor, a heat exchanger, a condenser, a heater, a cooler, a desulfurization device, a dehydration device, a dust collection filter, and the like.

5. Gas separation process

The above-described gas separation membrane can be used for a gas separation method for removing carbon dioxide or nitrogen.

Namely, the gas separation method of the present invention comprises:

(1) a step of supplying a mixed gas containing carbon dioxide or nitrogen to one surface of the gas separation membrane, and

(2) and obtaining a gas having a carbon dioxide concentration or a nitrogen concentration lower than that of the mixed gas from the other surface of the gas separation membrane.

In the present specification, a gas having a low carbon dioxide concentration or nitrogen concentration, which is a gas that has permeated through the gas separation membrane, is referred to as a "permeated gas", and a gas that has not permeated through the gas separation membrane and remains on the one surface of the gas separation membrane is referred to as a "concentrated gas".

In the gas separation method of the present invention, the gas separation membrane element of the present invention can be used.

In the gas separation method of the present invention, a gas separation membrane module having a pressure vessel and the gas separation membrane element of the present invention housed in the pressure vessel connected in series or in parallel may be used.

Further, the gas separation membrane element, and the gas separation membrane module (hereinafter, sometimes referred to as "gas separation membrane or the like") described above can separate a specific gas from a mixed gas by supplying the mixed gas to the membrane module and separating the gas into a permeated gas and a concentrated gas. In this case, the mixed gas may be supplied to the gas separation membrane or the like by increasing the pressure thereof with a compressor, or the permeation side of the gas separation membrane or the like may be reduced in pressure with a pump.

Further, the gas separation membrane elements and the gas separation membrane modules described above may be arranged in multiple stages to perform gas separation. When a multistage gas separation membrane element or gas separation membrane module is used, either the concentrated gas or the permeated gas of the gas separation membrane module in the preceding stage can be supplied to the gas separation membrane module in the succeeding stage.

Further, the concentrated gas or permeated gas in the gas separation membrane module of the subsequent stage may be mixed with the supply gas in the gas separation membrane module of the preceding stage. When the permeated gas and the concentrated gas are supplied to the gas separation membrane module in the subsequent stage, they may be pressurized by a compressor.

The supply pressure of the mixed gas is not particularly limited, but is preferably 0.1 to 10 MPa. By setting the pressure to 0.1MPa or more, the permeation rate of the mixed gas increases, and by setting the pressure to 10MPa or less, it is possible to prevent the member such as the gas separation membrane from being deformed by pressure.

The ratio of the pressure on the supply side to the pressure on the permeate side (pressure on the supply side/pressure on the permeate side) is also not particularly limited, but is preferably 2 to 20. By setting the pressure ratio to 2 or more, the permeation rate of the mixed gas can be increased, and by setting the pressure ratio to 20 or less, the running cost of the compressor on the supply side or the pump on the permeation side can be suppressed.

The supply temperature of the mixed gas is not particularly limited, but is preferably 0 to 200 ℃, and more preferably 25 to 180 ℃. By setting the temperature to 0 ℃ or higher, good gas permeability can be obtained, and by setting the temperature to 200 ℃ or lower, thermal deformation of the members of the gas separation membrane module can be prevented.

Further, the mixed gas preferably contains a light gas, particularly at least one of hydrogen and helium. In the gas separation membrane of the present invention, the difference between the permeability of hydrogen and helium and the permeability of carbon dioxide and nitrogen is large. Therefore, when the mixed gas contains at least one of hydrogen and helium, carbon dioxide and nitrogen can be efficiently removed by the gas separation membrane of the present invention.

Next, a gas separation method using the gas separation membrane element 1 will be described with reference to fig. 1. The supply gas 9 supplied from the 1 st end of the gas separation membrane element 1 flows into the supply-side flow path through the holes of the perforated end plate 7. In this way, the supply gas 9 that contacts the supply-side surface of the gas separation membrane 3 is separated into the permeated gas 11 and the concentrated gas 10 by the gas separation membrane 3.

The permeated gas 11 flows into the gas header 2 through the permeation-side flow path. The permeated gas 11 having passed through the gas header 2 flows out of the gas separation membrane element 1 from the 2 nd end of the gas separation membrane element 1. The concentrated gas 10 passes through the supply-side flow path and flows out of the gas separation membrane element 1 through the holes of the perforated end plate 7 provided at the 2 nd end. In this way, the feed gas 9 (mixed gas) can be separated into the permeated gas 11 and the concentrated gas 10.