FLUID SEPARATION MEMBRANE

Abstract

The present invention provides a fluid separation membrane that can maintain separation performance for a long period of time. The present invention provides a fluid separation membrane including a separation layer including a dense layer, wherein 2 to 10,000 ppm of a total of a monocyclic or bicyclic aromatic compound being liquid or solid at 16 C. under atmospheric pressure and 10 to 250,000 ppm of water are adsorbed.

Claims

1. A fluid separation membrane comprising a separation layer including a dense layer, wherein 2 to 10,000 ppm of a total of a monocyclic or bicyclic aromatic compound being liquid or solid at 16 C. under atmospheric pressure and 10 to 250,000 ppm of water are adsorbed.

2. The fluid separation membrane according to claim 1, wherein the aromatic compound is at least one selected from the group consisting of toluene, benzene, ethylbenzene, cumene, phenol, benzyl alcohol, anisole, benzaldehyde, benzoic acid, acetophenone, benzenesulfonic acid, nitrobenzene, aniline, thiophenol, benzonitrile, styrene, xylene, cresol, catechol, resorcinol, hydroquinone, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, and toluidine.

3. The fluid separation membrane according to claim 2, wherein the aromatic compound is at least one selected from the group consisting of toluene, benzene, and xylene.

4. The fluid separation membrane according to claim 3, wherein the aromatic compound is toluene.

5. The fluid separation membrane according to claim 4, wherein 2 ppm or more of toluene is adsorbed.

6. The fluid separation membrane according to claim 4, wherein the aromatic compound is also benzene.

7. The fluid separation membrane according to claim 6, wherein a ratio of a toluene adsorption amount (ppm) to a benzene adsorption amount (ppm) is 2 or more and 200 or less.

8. The fluid separation membrane according to claim 1, wherein a ratio of a water adsorption amount (ppm) to an adsorption amount of the aromatic compound (ppm) is 0.5 or more.

9. The fluid separation membrane according to claim 1, wherein a curve produced by plotting an amount of the aromatic compound of one kind generated in temperature programmed desorption-mass spectrometry with respect to a temperature change has two or more peaks, the amount of the aromatic compound being online measured while a temperature is raised from room temperature to 300 C. at 10 C./min.

10. The fluid separation membrane according to claim 1, wherein a curve produced by plotting an amount of water generated in temperature programmed desorption-mass spectrometry with respect to a temperature change has two or more peaks, the amount of water being online measured while a temperature is raised from room temperature to 300 C. at 10 C./min.

11. The fluid separation membrane according to claim 1, wherein the dense layer includes an inorganic material.

12. The fluid separation membrane according to claim 11, wherein the inorganic material is carbon.

13. The fluid separation membrane according to claim 1, wherein the dense layer is formed on a surface of a support having a porous structure.

14. The fluid separation membrane according to claim 13, wherein the porous structure is a three-dimensional network structure.

15. The fluid separation membrane according to claim 14, wherein the three-dimensional network structure is a co-continuous porous structure.

Description

EXAMPLES

[0089] Preferable Examples of the present invention will be described in the following, but the following description should not be construed as limiting the present invention.

[0090] [Method of Evaluation]

[0091] (Measurement of Adsorption Amounts of Aromatic Compound and Water)

[0092] The adsorption amounts of the aromatic compound and water were quantified by temperature programmed desorption-mass spectrometry (TPD-MS). The specific procedure is shown below. First, the surface of the fluid separation membrane was lightly wiped with a cloth. Next, a heating device equipped with a temperature controller was directly connected to a mass spectrometer, the fluid separation membrane was heated in a helium atmosphere, and the concentration of the gas generated from the fluid separation membrane during the heating was analyzed to determine the adsorption amounts of toluene, benzene, and water on the fluid separation membrane. In the temperature program, the temperature was first raised from room temperature to 80 C. at 10 C./min (step 1), held at 80 C. for 30 minutes (step 2), further raised to 180 C. at 10 C./min (step 3), and held at 180 C. for 30 minutes (step). The total of the amount of each of toluene, benzene, and water generated from step 1 through step 4 was obtained as the adsorption amount. The aromatic compound adsorption amount obtained only from the aromatic compound gas generated in steps 1 and 2 is named Aa (ppm), and the aromatic compound adsorption amount obtained only from the amount of the aromatic compound gas generated in steps 3 and 4 is named Ba (ppm), and similarly, the water adsorption amount obtained only from the water vapor generated in steps 1 and 2 is named Aw (ppm), and the water adsorption amount obtained only from the amount of the water vapor generated in steps 3 and 4 is named Bw (ppm). Ba/Aa and Bw/Aw were calculated.

[0093] (Generation Amount Curve During Heating of Aromatic Compound and Water)

[0094] In temperature programmed desorption-mass spectrometry (TPD-MS), the amounts of toluene, benzene, and water generated were online measured while the fluid separation membrane according to the present invention was heated from room temperature to 300 C. at 10 C./min, and at this time, the number of peaks of the curve produced by plotting the amount of toluene, benzene, or water generated with respect to the temperature change was confirmed. In order to exclude the influence of the liquid film and the liquid droplet on the surface of the fluid separation membrane, when the fluid separation membrane was visually wet, the surface of the fluid separation membrane was wiped with a rag or the like before the measurement was performed.

[0095] (Measurement of Gas Separation Factor)

[0096] Ten fluid separation membranes having a length of 10 cm were bundled and housed in a stainless steel casing having an outer diameter of 6 mm and a wall thickness of 1 mm, the end of the bundled fluid separation membranes was fixed to the inner face of the casing with an epoxy resin adhesive, and both the ends of the casing were sealed to produce a fluid separation membrane module, and the gas permeation rate was measured.

[0097] The measured gases were carbon dioxide and methane, and the pressure changes of the carbon dioxide and the methane at the permeation side per unit time were measured by an external pressure system at a measurement temperature of 25 C. in accordance with the pressure sensor method of JIS K7126-1 (2006). Herein, the pressure difference between the supply side and the permeation side was set to 0.11 MPa (82.5 cmHg).

[0098] Then, the permeation rate Q of the gas that had permeated was calculated by the formula described below, and the separation factor was calculated as the ratio of carbon dioxide/methane permeation rates. Note that the term STP means standard conditions. The membrane area was calculated from the outer diameter of the fluid separation membrane and the length of the region contributing to gas separation in the fluid separation membrane.

Permeation rate Q=[gas permeation volume (cm.sup.3.Math.STP)]/[membrane area (cm.sup.2)time(s)pressure difference (cmHg)]

[0099] The gas separation factor immediately after the start and the gas separation factor after 100 hours were measured. Furthermore, the latter was divided by the former to determine the separation factor retention rate after 100 hours of use.

Example 1

[0100] In a separable flask, 70 g of polyacrylonitrile (MW: 150,000) manufactured by Polysciences, Inc., 70 g of polyvinyl pyrrolidone (MW: 40,000) manufacturedby Sigma-Aldrich Co. LLC., and, as a solvent, 400 g of dimethyl sulfoxide (DMSO) manufactured by WAKENYAKU CO., LTD. were put, and the mixture was stirred and refluxed for 2.5 hours to prepare a solution at 135 C.

[0101] The obtained solution was cooled to 25 C., then the solution was discharged from the inner tube of a sheath-core double spinneret at 3.5 mL/min, a 90% by weight aqueous solution of DMSO was simultaneously discharged from the outer tube at 5.3 mL/min, and then the solutions were led to a coagulation bath containing pure water of 25 C., then withdrawn at a speed of 5 m/min, and wound up on a roller to obtain an original yarn. At this time, the air gap was 9 mm, and the immersion length in the coagulation bath was 15 cm.

[0102] The obtained original yarn was translucent and phase separation was caused in the original yarn. The obtained original yarn was washed with water and then dried at 25 C. for 24 hours in a circulation dryer to produce an original yarn.

[0103] After that, the dried original yarn was passed through an electric furnace at 255 C. and heated for 1 hour in an oxygen atmosphere to perform infusibilization treatment.

[0104] Subsequently, the infusibilized original yarn was carbonized under the conditions of a nitrogen flow rate of 1 L/min, a temperature rise rate of 10 C./min, a maximum temperature of 1,000 C., and a holding time of 1 minute to produce a porous carbon support. When the cross section was observed, a co-continuous porous structure was seen.

[0105] Then, 50 g of polyacrylonitrile (MW: 150,000) manufactured by Polysciences, Inc. and 400 g of dimethyl sulfoxide (DMSO) manufactured by WAKENYAKU CO., LTD. were put in a separable flask, the mixture was stirred and refluxed for 1.5 hours to prepare a solution at 135 C., and the solution was cooled to 25 C. Meanwhile, the porous carbon support was immersed, withdrawn at a speed of 10 mm/min, subsequently immersed in water to remove the solvent, and dried at 50 C. for 24 hours to produce a fluid separation membrane in which polyacrylonitrile was laminated on the porous carbon support.

[0106] Subsequently, the fluid separation membrane was carbonized under the conditions of a nitrogen flow rate of 1 L/min, a temperature rise rate of 10 C./min, a maximum temperature of 600 C., and a holding time of 1 minute to obtain a fluid separation membrane having a hollow fiber shape. A dense carbon layer was present on the outer surface, and the inside had a co-continuous structure including carbon.

[0107] Furthermore, 250 mL of toluene manufactured by KANTO CHEMICAL CO., INC., 250 mL of benzene manufactured by KANTO CHEMICAL CO., INC., and 250 mL of pure water were mixed and heated to 50 C., and the fluid separation membrane was exposed to the vapor of the mixture for 24 hours.

[0108] Then, the adsorption amounts of toluene, benzene, and water and the number of peaks of each generation amount curve during heating were confirmed, and the gas separation factor was measured.

Example 2

[0109] A fluid separation membrane was obtained in the same manner as in Example 1. Furthermore, 250 mL of toluene manufactured by KANTO CHEMICAL CO., INC. and 250 mL of pure water were mixed and heated to 50 C., and the fluid separation membrane was exposed to the vapor of the mixture for 24 hours.

[0110] Then, the adsorption amounts of toluene, benzene, and water and the number of peaks of each generation amount curve during heating were confirmed, and the gas separation factor was measured.

Example 3

[0111] A fluid separation membrane was obtained in the same manner as in Example 1. Furthermore, 250 mL of benzene manufactured by KANTO CHEMICAL CO., INC. and 250 mL of pure water were mixed and heated to 50 C., and the fluid separation membrane was exposed to the vapor of the mixture for 24 hours.

[0112] Then, the adsorption amounts of toluene, benzene, and water and the number of peaks of each generation amount curve during heating were confirmed, and the gas separation factor was measured.

Example 4

[0113] A fluid separation membrane was obtained in the same manner as in Example 1. Furthermore, 250 mL of toluene manufactured by KANTO CHEMICAL CO., INC. and 250 mL of pure water were mixed and heated to 50 C., and the fluid separation membrane was exposed to the vapor of the mixture for 4 hours.

[0114] Then, the adsorption amounts of toluene, benzene, and water and the number of peaks of each generation amount curve during heating were confirmed, and the gas separation factor was measured.

Comparative Example 1

[0115] A fluid separation membrane was obtained in the same manner as in Example 1. After that, adsorption treatment was not performed. The adsorption amounts of toluene, benzene, and water and the number of peaks of each generation amount curve during heating were confirmed, and the gas separation factor was measured.

Comparative Example 2

[0116] A fluid separation membrane was obtained in the same manner as in Example 1. Furthermore, 600 mL of water was heated to 50 C., and the fluid separation membrane was exposed to the vapor for 24 hours.

[0117] Then, the adsorption amounts of toluene, benzene, and water and the number of peaks of each generation amount curve during heating were confirmed, and the gas separation factor was measured.

[0118] The evaluation results of the fluid separation membranes produced in Examples and Comparative Examples are shown in Table 1.

TABLE-US-00001 TABLE 1 Carbon dioxide/methane separation factor Separation Adsorption amount Number of peaks of generation factor Toluene Benzene Water amount curve during heating Immediately After 100 retention (ppm) (ppm) (ppm) Ba/Aa Bw/Aw Toluene Benzene Water after start hours rate Example 1 310 22 30,000 0.61 0.37 2 2 2 5,889 5,712 0.97 Example 2 250 0 29,000 0.50 0.31 2 0 2 4,267 4,048 0.95 Example 3 0 30 22,000 0.31 0.33 0 2 2 3,963 3,686 0.93 Example 4 25 0 4,100 0.22 0.11 1 0 1 1,829 1,628 0.89 Comparative 0 0 1,500 1.26 0 0 1 990 485 0.49 Example 1 Comparative 0 0 22,000 1.26 0 0 2 3,023 2,150 0.71 Example 2