Carbon dioxide gas separation membrane, method for manufacturing same, and carbon dioxide gas separation membrane module
Provided are a CO 2 gas separation membrane, a method for manufacturing the same, and a carbon dioxide gas separation membrane module including the same, the CO 2 gas separation membrane including: a first layer (A) containing at least one alkali metal compound selected from the group consisting of an alkali metal carbonate, an alkali metal bicarbonate and an alkali metal hydroxide, and a first resin in which a polymer having a carboxyl group has been crosslinked; a second layer (B) containing at least one of the alkali metal compounds, and a second resin having a structural unit derived from a vinyl ester of a fatty acid; and a hydrophobic porous membrane (C).
1. A CO 2 gas separation membrane, comprising:
a first layer (A) including at least one alkali metal compound selected from the group consisting of an alkali metal carbonate, an alkali metal bicarbonate and an alkali metal hydroxide, and a first resin in which a polymer having a carboxyl group has been crosslinked;
a second layer (B) including at least one alkali metal compound selected from the group consisting of an alkali metal carbonate, an alkali metal bicarbonate and an alkali metal hydroxide, and a second resin having a structural unit derived from a vinyl ester of a fatty acid; and
a hydrophobic porous membrane (C),
wherein the polymer having a carboxyl group is a polyacrylic acid homopolymer, a polyitaconic acid homopolymer, a polycrotonic acid homopolymer, or a polymethacrylic acid homopolymer, and
the second resin is a polyvinyl alcohol, a vinyl alcohol-ethylene copolymer, a vinyl alcohol-acrylic acid copolymer, a vinyl alcohol-methacrylic acid copolymer, or a vinyl alcohol-vinylsulfonic acid copolymer.
2. The CO 2 gas separation membrane according to claim 1 , wherein
the second resin is a polyvinyl alcohol or vinyl alcohol-acrylic acid copolymer, the polyvinyl alcohol or the vinyl alcohol-acrylic acid copolymer being a partially saponified product of a vinyl ester of a fatty acid.
3. The CO 2 gas separation membrane according to claim 1 , wherein
a surface of the first layer (A) is in contact with a surface of the second layer (B), and a surface of the hydrophobic porous membrane (C) is in contact with one of the other surface of the first layer (A) and the other surface of the second layer (B).
4. The CO 2 gas separation membrane according to claim 3 , wherein
a weight per unit area of one of the first layer (A) and the second layer (B), which is not in contact with the hydrophobic porous membrane (C), is higher than that of the other layer in contact with the hydrophobic porous membrane (C).
5. The CO 2 gas separation membrane according to claim 1 , wherein
the first layer (A), the second layer (B), and the hydrophobic porous membrane (C) are stacked in this order.
6. The CO 2 gas separation membrane according to claim 1 , wherein
the first resin has a structural unit that is derived from an acrylic or methacrylic acid or a derivative thereof.
7. The CO 2 gas separation membrane according to claim 1 , wherein
a total amount of alkali metal compounds contained in the first layer (A) and the second layer (B) is 0.5 parts by mass to 20 parts by mass based on 1 part by mass of a total amount of the first and second resins.
8. The CO 2 gas separation membrane according to claim 1 , wherein
the alkali metal compounds contained in the first layer (A) and the second layer (B) are each a carbonate or hydroxide of at least one alkali metal selected from the group consisting of sodium, potassium, rubidium and cesium.
9. The CO 2 gas separation membrane according to claim 1 , wherein
the alkali metal compounds contained in the first layer (A) and the second layer (B) are each cesium carbonate or cesium hydroxide.
10. The CO 2 gas separation membrane according to claim 1 , wherein
the hydrophobic porous membrane (C) includes at least one material selected from the group consisting of ceramic, a fluorine-containing resin, polyphenylene sulfide, polyether sulfone, and polyimide.
11. The CO 2 gas separation membrane according to claim 1 , wherein
the hydrophobic porous membrane (C) has pores with an average pore diameter of 0.005 μm to 1.0 μm.
12. A method for manufacturing the CO 2 gas separation membrane according to claim 1 , comprising:
a first step of applying a first coating liquid containing the alkali metal compound, the first resin and a medium or a second coating liquid containing the alkali metal compound, the second resin and a medium onto at least one surface of the hydrophobic porous membrane (C);
a second step of forming the first layer (A) or the second layer (B) by removing the medium from a coating obtained in the first step;
a third step of applying one of the first coating liquid and the second coating liquid, which is different from the coating liquid used in the first step, onto a surface of the first layer (A) or the second layer (B) formed in the second step; and
a fourth step of forming the first layer (A) or the second layer (B) by removing the medium from a coating obtained in the third step.
13. The method according to claim 12 , wherein
the first step is a step of applying the second coating liquid onto at least one surface of the hydrophobic porous membrane (C).
14. A method for separating CO 2 , comprising the steps of:
feeding a gas mixture that contains at least CO 2 and water vapor on a surface side of the CO 2 gas separation membrane according to claim 1 ; and
recovering CO 2 separated from the gas mixture through the other surface side of the CO 2 gas separation membrane.
15. A CO 2 gas separation membrane module comprising the CO 2 gas separation membrane according to claim 1 .
16. A CO 2 gas separation apparatus, comprising:
the CO 2 gas separation membrane module according to claim 15 ; and
a gas feeding part for feeding a gas mixture that contains at least CO 2 and water vapor to the CO 2 gas separation membrane module.