JP-2026076373-A - Separation membrane, method for manufacturing a separation membrane, and coating solution for manufacturing a separation membrane

Abstract

[Problem] To provide a separation membrane with high separation performance for mixed gases containing acidic gases. [Solution] The separation membrane 10 of the present invention comprises a separation functional layer 1 containing graphene oxide, an ionic liquid, and a polymer. The ionic liquid is, for example, hydrophilic and contains imidazolium ions and tetrafluoroborate. The method for producing the separation membrane 10 of the present invention includes applying a coating solution containing graphene oxide, an ionic liquid, and a polymer to a substrate to obtain a coating film, and drying the coating film. [Selection Diagram] Figure 1

Inventors

• 吉村 和也
• 木村 直道
• 西山 真哉

Assignees

• 日東電工株式会社

Dates

Publication Date

20260511

Application Date

20260220

Priority Date

20200917

Claims (16)

1. A separation membrane comprising a separation functional layer containing graphene oxide, an ionic liquid, and a polymer.
2. The separation membrane according to claim 1, wherein the ionic liquid is hydrophilic.
3. The separation membrane according to claim 1 or 2, wherein the ionic liquid contains imidazolium ions.
4. The separation membrane according to any one of claims 1 to 3, wherein the ionic liquid contains tetrafluoroborate.
5. The separation membrane according to any one of claims 1 to 4, wherein the content of the ionic liquid in the separation functional layer is 50 wt% or more.
6. The separation membrane according to any one of claims 1 to 5, wherein the polymer is compatible with both the graphene oxide and the ionic liquid.
7. The separation membrane according to any one of claims 1 to 6, wherein the polymer has polar groups.
8. The separation membrane according to claim 7, wherein the polar group comprises at least one selected from the group consisting of a hydroxyl group, an ether group, and an amide group.
9. The separation membrane according to any one of claims 1 to 8, wherein the polymer comprises a polyether block amide.
10. A separation membrane according to any one of claims 1 to 9, further comprising a porous support that supports the separation functional layer.
11. The separation membrane according to claim 10, further comprising an intermediate layer disposed between the separation functional layer and the porous support.
12. A separation membrane according to any one of claims 1 to 11, used for separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.
13. A coating solution containing graphene oxide, an ionic liquid, and a polymer is applied to a substrate to obtain a coating film. Drying the aforementioned coating film, A method for producing a separation membrane, including the following:
14. The manufacturing method according to claim 13, wherein the viscosity of the coating solution at 25°C is 0.15 Pa·s or more.
15. A coating solution applied to a substrate in order to manufacture a separation membrane, A coating solution comprising graphene oxide, an ionic liquid, and a polymer.
16. The coating solution according to claim 15, wherein the viscosity of the coating solution at 25°C is 0.15 Pa·s or more.

Description

This invention relates to a separation membrane, a method for manufacturing a separation membrane, and a coating solution for manufacturing a separation membrane. Membrane separation is a method developed to separate acidic gases, such as carbon dioxide, from gas mixtures. Compared to absorption methods, which separate acidic gases by absorbing them with an absorbent, membrane separation can efficiently separate acidic gases while reducing operating costs. Examples of separation membranes used in membrane separation methods include composite membranes in which a separation functional layer is formed on a porous support. An intermediate layer may be placed between the separation functional layer and the porous support (for example, Patent Document 1). Patent Document 1 discloses a gel layer containing a polymer and an ionic liquid as the separation functional layer. Japanese Patent Publication No. 2015-160159 This is a cross-sectional view of a separation membrane according to one embodiment of the present invention.This is a schematic cross-sectional view of a membrane separation apparatus equipped with the separation membrane of the present invention.This is a schematic perspective view showing a modified example of a membrane separation apparatus equipped with the separation membrane of the present invention.This graph shows the results of X-ray diffraction measurements performed on the separation functional layer of the separation membranes in Example 1 and Comparative Example 1. The following describes the details of the present invention, but this description is not intended to limit the present invention to any particular embodiment. <Embodiment of separation membrane> As shown in Figure 1, the separation membrane 10 of this embodiment comprises a separation functional layer 1, and further comprises, for example, an intermediate layer 2 and a porous support 3. The porous support 3 supports the separation functional layer 1. The intermediate layer 2 is disposed between the separation functional layer 1 and the porous support 3 and is in direct contact with both the separation functional layer 1 and the porous support 3. (separation functional layer) The separation functional layer 1 is a layer that can preferentially permeate acidic gases contained in the mixed gas. The separation functional layer 1 comprises graphene oxide (GO), an ionic liquid (IL), and a polymer. The ionic liquid is, for example, a salt (ionic compound) that is liquid below 100°C, and is typically a salt that is liquid at 25°C. For example, in the separation functional layer 1, multiple layers of graphene oxide are arranged in layers. The ionic liquid and polymer may be present between the layers of multiple layers of graphene oxide. The graphene oxide and polymer may be dispersed in the ionic liquid or may be present randomly. The graphene oxide contained in the separation functional layer 1 is, for example, an oxide of graphene, and has a structure in which a functional group containing an oxygen atom is introduced into the graphene. Examples of functional groups containing an oxygen atom include hydroxyl groups, carboxyl groups, and epoxy groups. The graphene oxide may also be reduced graphene oxide (rGO), in which some of the functional groups containing oxygen atoms are reduced. The graphene oxide may contain substituents other than functional groups containing oxygen atoms, such as substituents containing nitrogen atoms (e.g., amino groups), but it is preferable that it is substantially free of such substituents. More specifically, it is preferable that the graphene oxide is substantially free of substituents derived from the ionic liquid, which may be introduced by reaction with the ionic liquid. The content of graphene oxide in the separation functional layer 1 is, for example, 0.01 wt% or more, preferably 0.02 wt% or more, from the viewpoint of improving the separation performance of the separation functional layer 1. The upper limit of the graphene oxide content is not particularly limited, but is, for example, 1 wt%, preferably 0.5 wt%, more preferably 0.1 wt%, and even more preferably 0.05 wt%. The ionic liquid contained in the separation functional layer 1 includes, for example, at least one selected from the group consisting of imidazolium ions, pyridinium ions, ammonium ions, and phosphonium ions, and preferably includes imidazolium ions. These ions include, for example, substituents having one or more carbon atoms. Examples of substituents having one or more carbon atoms include alkyl groups having one to twenty carbon atoms, cycloalkyl groups having three to fourteen carbon atoms, and aryl groups having six to twenty carbon atoms. These may be further substituted with hydroxyl groups, cyano groups, amino groups, monovalent ether groups, etc. (for example, hydroxyalkyl groups having one to twenty carbon atoms). Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-