Method of producing composite for acid gas separation
Preparing forming coating liquid for an acid gas separation facilitated transport membrane which includes a hydrophilic compound, an acid gas carrier, and water, coating the forming coating liquid, using a layered film layered in the order of a hydrophilic porous film, a hydrophobic porous film, and an auxiliary support film as a porous support, on a surface of the hydrophilic porous film of the layered film with a liquid film thickness of 0.3 mm to 1.0 mm and drying the coated liquid to form a first acid gas separation facilitated transport membrane, and further coating the forming coating liquid for the acid gas separation facilitated transport membrane on the surface of the hydrophilic porous film with the previously formed acid gas separation facilitated transport membrane and drying the coated liquid to form a next acid gas separation facilitated transport membrane.
1. A method of producing a composite for acid gas separation with an acid gas separation facilitated transport membrane having a function of separating an acid gas in a raw gas on a porous support, the method comprising:
a coating liquid preparation step in which a forming coating liquid for the acid gas separation facilitated transport membrane is prepared, the forming coating liquid including a hydrophilic compound, an acid gas carrier, and water;
an initial layer forming step in which a first acid gas separation facilitated transport membrane is formed by coating the forming coating liquid, using a layered film layered in the order of a hydrophilic porous film, a hydrophobic porous film, and an auxiliary support film as the porous support, on a surface of the hydrophilic porous film of the layered film with a liquid film thickness of 0.3 mm to 1.0 mm and drying the coated coating liquid; and
a next layer forming step in which a next acid gas separation facilitated transport membrane is formed by further coating the forming coating liquid for the acid gas separation facilitated transport membrane on the surface of the hydrophilic porous film with the previously formed acid gas separation facilitated transport membrane and drying the coated coating liquid, the next layer forming step being performed one or more times,
wherein the forming coating liquid for the acid gas separation facilitated transport membrane has a temperature of 15° C. to 35° C. at the time of coating and a viscosity measurement value of 0.5 Pa·s to 5 Pa·s in B-type viscosity measurement at a rotation speed of 60 rpm,
wherein, in the coating liquid preparation step, a plurality of forming coating liquids which differ in concentration of the acid gas carrier is prepared as the forming coating liquid for the acid gas separation facilitated transport membrane, and
wherein, in a next layer forming step, a forming coating liquid which has a concentration of the acid gas carrier lower than that of the forming coating liquid used for the previously formed acid gas separation facilitated transport membrane is used.
2. The method of producing a composite for acid gas separation of claim 1 , wherein the forming coating liquid for the acid gas separation facilitated transport membrane is coated with a liquid film thickness of less than or equal to 3.0 mm in the next layer forming step.
3. The method of producing a composite for acid gas separation of claim 1 , wherein a roll coating method or a blade coating method is used to perform at least one of the coating in the initial layer forming step or the coating in the next layer forming step.
4. The method of producing a composite for acid gas separation of claim 1 , wherein the hydrophilic compound is a polyvinyl alcohol-polyacrylic acid copolymer.
5. The method of producing a composite for acid gas separation of claim 1 , wherein the acid gas carrier includes a compound containing at least one selected from alkali metal carbonates.