JP2011206721A - Gas-liquid contact membrane, gas-liquid contact membrane module, and gas recovering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-liquid contact membrane of high performance capable of highly efficiently bringing gas and liquid into contact with each other.SOLUTION: The gas-liquid contact membrane has fine holes, wherein the pitch of the fine holes is 30-1,000 nm; the diameter of the fine holes is 10-300 nm; the thickness of the gas-liquid contact membrane is 30-1,000 nm, and a standard deviation of the fine holes in the hole diameter distribution is 30% or less of an average value.

Description

  The present invention relates to a gas-liquid contact film used for dissolving a gas in a liquid.

Conventionally, in many fields such as the chemical industry, dissolution of gas (hereinafter also referred to as “gas”) into a liquid and recovery operation of the gas from the liquid, so-called gas-liquid contact operation, have been frequently performed. . For example, the oxygen supply to the microbial broth in the pharmaceutical field, the ozone dissolution into ultra pure water line in the electronics industry, oxygen supply to the fish in the fishing industry, as well as an exhaust gas, such as NO _x and SO _x in the chemical plant or thermal power plant Processing.

In recent years, there has been a demand for reducing greenhouse gas emissions in various situations. In particular, separation and recovery of carbon dioxide (CO ₂ ), which has the largest emission amount, is an urgent task, and research is being conducted to separate carbon dioxide from the fuel exhaust gas of a thermal power plant. In addition, carbon dioxide removal from landfill gas (gas generated from landfill disposal site) or digestion gas (gas generated during the digestion process of sludge) is also an important issue.

  These treatments are technologies for separating carbon dioxide from mixed gas containing carbon dioxide gas, and various methods have been adopted. Recently, separation technology using hollow fibers has been proposed as a highly efficient and economical method. (See Non-Patent Document 1). However, what has been mainly studied is a method of using the hollow fiber itself as a membrane, and the selectivity (corresponding to gas separation ability) and permeability (corresponding to the throughput of the entire apparatus) of the gas species that permeate the membrane. ) Is not necessarily sufficient (see Non-Patent Document 2).

  On the other hand, a simple gas-liquid contact device using a hollow fiber having no gas separation ability as a support for a liquid membrane has been proposed. In particular, a method using a hydrophobic porous hollow fiber as a support for a liquid membrane is efficient. It attracts attention as a technique that enables good carbon dioxide removal (see Non-Patent Document 3). This technique removes carbon dioxide from a mixed gas by utilizing the difference in mobility of the mixed gas component to the liquid film. At this time, it is known that the removal performance can be improved by using a solution having high reactivity with carbon dioxide such as an aqueous amine solution for the liquid film.

  Further, as a technique for improving the carbon dioxide recovery efficiency by the membrane structure, a method of changing the membrane permeation performance at both ends (see Patent Documents 1 and 2) is disclosed. However, there is a limit to the design of the pores of the membrane, and the carbon dioxide recovery efficiency is not yet efficient, and an innovative design of the pores of the membrane has been desired.

JP 2005-305263 A Japanese Patent Laying-Open No. 2005-305264

J. et al. R. Pena: Symp Pap Energy Biomass Waters, 8 (1984), 1021-1051. T.A. Kawai: Tansangasu Kaisyu Gijutsu, (NTS, Tokyo, 1991), PP. 22. A. Gabelman and S.M. Hwang: J Membr Sci, 159 (1999), 61-106.

  An object of the present invention is to provide a gas-liquid contact film module capable of recovering a specific gas from a mixed gas containing the specific gas in a short time and with a high recovery rate, a gas-liquid contact film used in the module, and a gas-liquid contact film laminate And a gas recovery method using the module.

As a result of intensive studies to solve the above-mentioned problems, the present inventor is able to recover CO ₂ with a high recovery rate in a short time by a CO ₂ recovery gas-liquid contact membrane with a very narrow pore size distribution. The present inventors have found that this can be done and have completed the present invention.

  That is, the present invention relates to the following gas-liquid contact film and method for producing the same, gas-liquid contact film laminate and method for producing the same, gas-liquid contact film module, and gas recovery method.

  1. A gas-liquid contact membrane having pores, wherein the pore pitch of the pores is 30 to 1000 nm, the pore diameter of the pores is 10 to 300 nm, and the thickness of the gas-liquid contact membrane is 30 to A gas-liquid contact membrane having a thickness of 1000 nm and a standard deviation in the pore size distribution of the pores of 30% or less of the average value.

2. Transferring the irregularities of the first mold having recesses made of pores to a second mold, and transferring the irregularities of the second mold to a film made of a polymer;
The manufacturing method of the gas-liquid contact film | membrane of said 1 containing said.

  3. 3. The manufacturing method according to 2 above, wherein the first mold having a recess composed of the pores is produced by anodizing an aluminum plate.

4). A step of transferring the irregularities of the third mold having projections made of protrusions to the first mold;
Transferring the irregularities of the first mold to a second mold, and transferring the irregularities of the second template to a film made of a polymer;
The manufacturing method of the gas-liquid contact film | membrane of said 1 containing said.

  5. 5. The manufacturing method according to 4 above, wherein the third mold having a convex portion composed of the protrusion is produced by developing the photoresist layer laminated on the substrate by interference exposure.

  6). A gas-liquid contact film laminate obtained by laminating the gas-liquid contact film according to 1 and a porous film substrate.

7). A step of laminating the gas-liquid contact film and the porous film substrate according to 1 above, and a step of melting the gas-liquid contact film and / or the porous film substrate by heating and fusing them together,
The manufacturing method of the gas-liquid contact film | membrane laminated body containing this.

  8). The gas-liquid contact film according to the above 1 or the gas-liquid contact film laminate according to the above 6 comprises a container in which the internal space is separated into a first space and a second space, and the first space from the external space A gas-liquid contact membrane module having a gas inlet and a gas outlet, and having a liquid inlet and a liquid outlet from the external space in the second space.

  9. By flowing a mixed gas containing a specific gas from the gas inlet to the gas outlet of the gas-liquid contact membrane module according to 8 above, and flowing a liquid that absorbs the specific gas from the liquid inlet toward the liquid outlet A gas recovery method including a step of causing the liquid to absorb the specific gas.

  10. 10. The method according to 9 above, wherein the specific gas is carbon dioxide.

  Since the gas-liquid contact membrane of the present invention has a narrow pore size distribution, the gas-liquid contact operation can be performed at a high pressure relative to the average pore size, and the specific gas can be recovered from a mixed gas containing a specific gas in a short time with a high recovery rate. Gas can be recovered.

It is a cross-sectional schematic diagram which shows the one aspect | mode of the gas-liquid contact film | membrane of this invention. It is a figure which shows the process of producing the 1st casting_mold | template which consists of an anodic oxidation porous alumina which has the recessed part which consists of pores. It is a figure which shows the process which transfers the unevenness | corrugation of the 3rd casting_mold | template which has a convex part which consists of protrusions to a 1st casting_mold | template. It is a figure which shows an example of the process which produces a gas-liquid contact film | membrane from the 1st casting_mold | template which has a recessed part which consists of pores. It is a cross-sectional schematic diagram which shows the module of this invention used in Example 1 and 2. FIG. 3 is a schematic cross-sectional view showing a hollow fiber module used in Comparative Example 1. FIG. It is a cross-sectional schematic diagram which shows the flat membrane module used in the comparative example 2.

Hereinafter, the present invention will be described in detail.
The gas-liquid contact film of the present invention has pores, the pore pitch of the pores is 30 to 1000 nm, the pore diameter of the pores is 10 to 300 nm, and the thickness of the gas-liquid contact film And a standard deviation in the pore size distribution of the pores is 30% or less of the average value. In addition, the pore in this invention means the hole which has a fine dimension about 10-300 nm in diameter.

  In the gas-liquid contact film of the present invention, a mixed gas containing a specific gas is arranged on one side, a liquid that absorbs the specific gas is arranged on the other side, and gas-liquid contact is made through the pores of the film, The specific gas can be recovered from the mixed gas containing the specific gas in a short time and with a high recovery rate.

In general, in a state where a mixed gas and a liquid are in contact with each other, the solubility of a specific gas in the mixed gas in the liquid follows Henry's law expressed by the following equation (1). In the formula, P is a partial pressure of the specific gas in the mixed gas, χ is a molar fraction of the specific gas dissolved in the liquid, and K is a constant.
P = Kχ (1)

  That is, the greater the partial pressure of the specific gas, the greater the solubility in the liquid. However, when the mixed gas is brought into contact with the liquid via the gas-liquid contact film, if the pressure of the mixed gas is increased too much in order to increase the dissolution efficiency of the specific gas, the mixed gas passes through the pores and becomes liquid. Bubbles are generated in the inside (also referred to as “a bubbling phenomenon”). When the pore diameter of the gas-liquid contact film is distributed, the maximum pressure at which this bubbling phenomenon does not occur depends on the maximum pore diameter of the gas-liquid contact film. Therefore, a gas-liquid contact membrane having the same average pore size but a narrow pore size distribution can increase the maximum pressure that does not cause a bubbling phenomenon, and can also increase the solubility of a specific gas in a liquid. In order to exert such an effect, the standard deviation in the pore size distribution of the pores of the gas-liquid contact membrane is 30% or less of the average value, preferably 20% or less, and preferably 10% or less. Is more preferable.

  In addition, since the gas-liquid contact film of the present invention has higher surface smoothness than a porous film substrate described later, the local residence of the fluid in contact is reduced, the concentration boundary layer is thinned, and the liquid side substance It is considered that the movement is promoted and the gas can be efficiently dissolved.

  Another aspect of the present invention is a gas-liquid contact film laminate formed by laminating the gas-liquid contact film and a porous film substrate. As described above, since the gas-liquid contact film of the present invention has high surface smoothness compared to the porous film substrate, when using it for a gas-liquid contact film laminate, a liquid is allowed to flow to the gas-liquid contact film side. It is preferable to flow a gas to the porous film substrate side because the gas recovery efficiency to the liquid is increased.

Hereinafter, preferred embodiments of the gas-liquid contact film of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing one embodiment of a thin film used for the gas-liquid contact film of the present invention. The pores of the gas-liquid contact film of this embodiment have a tapered shape in which the pore diameter increases from the thin film surface to the back surface. When the gas-liquid contact film of the present invention is produced by the production method described later, in the step of releasing the gas-liquid contact film from the mold when the pore diameter is uniform from the front surface to the back surface of the gas-liquid contact film, The taper shape of this embodiment is more preferable because the thin film cannot be peeled smoothly and defects may occur.

Next, the manufacturing method of the gas-liquid contact film | membrane of this invention is demonstrated.
The first manufacturing method includes a step of transferring the unevenness of the first mold having a recess made of pores to a second template, and a step of transferring the unevenness of the second template to a film made of a polymer. It is a manufacturing method of a gas liquid contact film. Here, the first mold can be preferably produced by, for example, anodizing an aluminum plate.

  The second manufacturing method includes a step of transferring the unevenness of the third mold having a protrusion made of a protrusion to the first mold, a step of transferring the unevenness of the first mold to the second template, and the second The method for producing a gas-liquid contact film includes a step of transferring the irregularities of the mold 2 to a film made of a polymer. Here, the third mold can be suitably produced, for example, by developing the photoresist layer laminated on the substrate by interference exposure.

  In the above two types of manufacturing methods, the first mold is a mold having a concave portion formed of pores as in the gas-liquid contact film of the present invention. In addition, the second mold and the third mold are molds having protrusions made of protrusions contrary to the gas-liquid contact film of the present invention, and the first mold is in a positive and negative relationship. .

The first manufacturing method will be described in more detail.
FIG. 2 shows a method for producing a first mold (anodized porous alumina) having a recess made of pores. The anodized porous alumina 3 is formed on the surface of the aluminum substrate 2 by anodization. The pores 4 of the anodized porous alumina 3 have a cylindrical shape having a substantially constant diameter except for the bottom. If this is used as a mold as it is, the thin film cannot be smoothly peeled off from the mold, which may cause defects.

  On the other hand, a method of manufacturing a stamper for producing an antireflection film made of anodized porous alumina having a hole having a desired tapered shape by combining anodization and pore enlargement processing by etching is known (special feature). No. 2005-156695).

  Briefly describing the above method, after anodizing the aluminum substrate 2 for a predetermined time to form pores of a desired depth, the pore diameter is expanded by immersing in an appropriate acid solution. Do. Thereafter, anodization is performed again to form pores having a smaller pore diameter than in the first stage. By repeating this operation, anodized porous alumina having tapered pores can be obtained. By increasing the number of repeated steps, smoother tapered pores can be obtained. By adjusting the anodic oxidation time and the pore diameter expansion processing time, it is possible to form pores having various tapered shapes. By using this method for the production of a gas-liquid contact film, the pitch and depth of the pores can be obtained. It is considered that the optimum structure of the gas-liquid contact film can be designed accordingly.

  In addition, an anode having a high hole arrangement regularity is obtained by using anodized porous alumina prepared by anodizing at a constant voltage for a long time, once removing the oxide film, and again anodizing under the same conditions. It becomes possible to use oxidized porous alumina as a mold.

  As the anodized porous alumina to be used, for example, anodized porous alumina prepared using oxalic acid as an electrolytic solution at a conversion voltage of 30 V to 60 V can be used. Alternatively, anodized porous alumina produced using sulfuric acid as the electrolytic solution and at a conversion voltage of 25V to 30V can be used. By using such anodized porous alumina, it is possible to obtain a template having a dent array with higher regularity.

  Furthermore, in the preparation of anodized porous alumina, a fine depression can be formed on the aluminum surface prior to anodization, and this can be used as a pore generation point during anodization. A depression array having an arbitrary arrangement can be used as a template. It becomes possible to do.

The second template can be obtained by filling the pores of the first template produced by the above method with a substance such as metal, metal oxide, or polymer, and then removing the first template.
Metals, metal oxides, but are not particularly limited, is generally Ni, Ta, SiO _2, carbon, organic SOG or the like is used. Among these examples, Ni is preferable because it is easily electroformed.

  Further, the polymer filled in the pores of the first template is not limited as long as it has processability, but as a typical one, fluorine-based resin (polytetrafluoroethylene, tetrafluoroethylene- Perfluoroalkoxy trifluoride ethylene copolymer, tetrafluoroethylene-6-fluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, polytrifluoroethylene chloride, polyvinylidene fluoride, polyvinyl fluoride, Teflon (Registered trademark) AF (registered trademark: manufactured by DuPont), Hyflon AD (registered trademark: manufactured by Solvay Solexis), Cytop (registered trademark: manufactured by Asahi Glass)), acrylic resin, polycarbonate, polystyrene, polysulfone, polyethersulfone , Polyvinyl alcohol, ethylene / vinyl alcohol copolymer, Loin, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, nylon, polyimide, polyamide, polyphenylene sulfide, polyarylate, as well as their copolymers. Further, after the polymer monomer is filled in the first mold, it may be polymerized by light such as UV and / or heat. Among these examples, the fluororesin is preferable because it is excellent in releasability from the first mold.

  Furthermore, a gas-liquid contact film can be obtained by filling the second template with a polymer and then releasing the polymer film from the second template.

  The method for transferring the polymer to the second template is not particularly limited, and methods such as optical imprinting, thermal imprinting, room temperature imprinting, and nanocasting imprinting can be used. The polymer does not cause adhesion or fusion with the material of the second mold when filled in the second mold, and is resistant to a liquid that dissolves a specific gas to be collected. There is no particular limitation.

  In particular, when the specific gas to be collected is carbon dioxide, an alkaline liquid such as ethanolamine is usually used as the liquid for dissolving carbon dioxide, and thus the polymer preferably has high alkali resistance. Typical examples include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy trifluoride ethylene copolymer, tetrafluoroethylene-6 fluoropropylene copolymer, Teflon (registered trademark) AF, Hyflon AD ( (Registered trademark), fluororesin such as Cytop (registered trademark), polystyrene, polysulfone, polyethersulfone, polyethylene, polypropylene, polyphenylene sulfide, polyarylate, and copolymers thereof. These are preferable because of their high durability.

  Alternatively, after the polymer monomer is filled in the second template, it may be polymerized by light such as UV and / or heat. Among these, a fluororesin is more preferable because it is excellent in releasability from the second mold.

  When the volume of the polymer used for transfer is larger than the volume of the concave / convex gap formed by the protrusions of the second mold, the pores on one side of the gas-liquid contact film are blocked with an extra remaining film. Therefore, it is necessary to remove the residual film by etching before or after releasing to form a through-hole thin film. Examples of the etching method include high vacuum dry etching using plasma, atmospheric pressure dry etching, wet etching using a solvent, and the like. Among these, atmospheric pressure dry etching is preferable because of low cost and high etching accuracy.

An example of a process for producing a gas-liquid contact film by the above steps is shown in FIG.
A surface conductive layer made of Ni-P, Au, Cr or the like is formed on the surface of the first mold made of anodized porous alumina 3 by electroless plating or sputtering, and then the second mold is made by electrolytic plating of Ni or the like. Form. The second template is obtained by peeling the second template from the first template or selectively dissolving and removing the first template. Next, the second template is filled with a polymer, for example, a solution in which polysulfone is dissolved in a solvent, and the solvent is dried to obtain a thin film made of the polymer. After the polymer film filled in excess of this thin film is removed by plasma etching, it is peeled from the second mold to obtain a gas-liquid contact film. The gas-liquid contact film laminate of the present invention can be obtained by laminating the gas-liquid contact film and the porous film substrate.

Next, the second manufacturing method will be described in more detail.
FIG. 3 shows a method for producing a first mold having a concave portion made of a pore from a third mold having a convex portion made of a protrusion.

  The third mold can be suitably produced by an interference exposure method. First, a positive photoresist is applied on a smooth substrate 7 (for example, a polished glass master). A positive photoresist is a resist well known in the technical field of semiconductor device manufacturing, and is a composition containing a resin having a phenolic hydroxyl group and a photoacid generator. This composition has low solubility in an alkaline developer before light irradiation, but acid is generated by light irradiation and the solubility in an alkaline developer is increased. Patterning can be performed by utilizing the difference in solubility between the light irradiated portion and the light non-irradiated portion with respect to the developer. Hereinafter, the light non-irradiated part is also referred to as a cured part, and the light irradiated part is also referred to as an uncured part.

  Next, exposure is performed by an interference exposure method using laser light (hereinafter also referred to as “laser interference exposure method”) to obtain a hardened portion formed of fine tapered protrusions and a remaining uncured portion. After the exposure, development is performed to remove the uncured portion, thereby obtaining a third mold 9 having a convex portion 8 made of a protrusion.

  The convex portion 8 formed in the photoresist has a so-called tapered shape in which the top portion 8a of the convex portion is thinned and the bottom portion 8b is thickened by a laser interference exposure method. This phenomenon is such that the laser beam power intensity is strong on the photoresist surface and becomes weaker as it travels through the photoresist. As a result, the exposure amount increases on the photoresist surface and the top 8a is eroded, resulting in the depth of the photoresist. It is thought that this is because the exposure amount becomes smaller as the process proceeds in the vertical direction, the erosion in the depth direction becomes weaker, and the bottom surface portion 8b expands. Therefore, the taper angle can be adjusted according to the photosensitivity (γ value) of the photoresist.

The laser interference exposure method is an exposure method using interference fringes formed by irradiating laser light of a specific wavelength from two directions of angle θ ′, and is used by changing the angle θ ′. The structure of the concavo-convex lattice having various pitches can be obtained within a range limited by the wavelength of the laser. For example, an uneven pattern composed of the above-mentioned tapered protrusions can be formed by overlapping and exposing three sets of the interference fringes whose directions are shifted by 120 degrees.
Lasers that can be used for interference exposure are limited to TEM00 mode lasers. Examples of the ultraviolet laser capable of laser oscillation in the TEM00 mode include an argon laser (wavelengths 364 nm, 351 nm, and 333 nm), and a fourth harmonic wave (wavelength 266 nm) of a YAG laser.

  The taper angle can also be changed by etching the formed pattern. That is, in high vacuum plasma etching, the taper angle can be changed by controlling the anisotropy of etching.

  In general, the longer the mean free path of the incident reactive ions is made lower and the gas is vertically incident, the anisotropy increases. However, in this case, since the etching is uniformly performed in the vertical direction, the taper is tapered. The change in angle is small. On the other hand, by setting the pressure higher, the incidence of reactive ions in the lateral direction increases and etching is also performed in the lateral direction, thereby changing the taper angle.

  As shown in FIG. 3B, the surface casting layer is formed on the third mold produced by the above method, and then Ni electroforming is performed to form the first mold. When the third mold is removed, the first mold 10 having the transferred irregularities is obtained by reversing the irregularities (FIG. 3C).

  Using the first template produced by the above method, the hole is filled with a substance such as metal, metal oxide, or polymer, and then the first template is removed to obtain a second template. Can do.

  The second mold produced by the second production method is filled with a polymer and released from the second mold in the same manner as the second mold produced by the first production method. A gas-liquid contact film having a tapered shape in which the pore diameter continuously changes and having a very small pore diameter distribution can be obtained.

  According to the above manufacturing method, the pore pitch is 30 to 1000 nm, the pore diameter is 10 to 300 nm, the pore depth is 30 nm to 1000 nm, and the pore diameter distribution of the pore diameter is extremely narrow. A gas-liquid contact film can be obtained. The very small pore size distribution means that the standard deviation in the pore size distribution is 30% or less of the average value, preferably 20% or less, more preferably 10% or less. Say something.

  The porosity of the gas-liquid contact film of the present invention is not particularly limited, but is usually 25% or more and 95% or less, preferably 40% or more, more preferably 50% or more, and particularly preferably 60% or more. . If it is 25% or more, it is excellent in water permeability, and if it is 95% or less, sufficient strength used as a gas-liquid contact film can be secured.

  The gas-liquid contact film obtained by the above production method can be used as it is, but is preferably used as a gas-liquid contact film laminate by laminating it with a porous film substrate in order to increase mechanical strength. Examples of the porous film substrate include a microporous membrane, a nonwoven fabric, a phase separation membrane, and a stretched aperture membrane.

  The material of the porous film substrate is not particularly limited as long as it has corrosion resistance against a liquid that dissolves a specific gas to be collected.

For example, in the case of a gas-liquid contact film laminate for CO ₂ recovery, the material of the porous film substrate may be made of a material having high alkali resistance because an alkaline liquid such as ethanolamine is used as the CO ₂ absorbent. preferable. Typical examples include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy trifluoride ethylene copolymer, tetrafluoroethylene-6 fluoropropylene copolymer, Teflon (registered trademark) AF, Hyflon AD ( Fluorine resins such as (registered trademark) and Cytop (registered trademark), polystyrene, polysulfone, polyethersulfone, polyethylene, polypropylene, polyphenylene sulfide, polyarylate, and copolymers thereof are preferred because of their high durability.

  The pore diameter of the porous film substrate is preferably larger than the pore diameter of the gas-liquid contact membrane, and more preferably in the range of 1 to 100 μm. In addition, the thickness of the porous film substrate is preferably 10 to 1000 μm in view of the balance between strength and porosity. In general, the gas-liquid contact film is laminated on the porous film substrate by superimposing the gas-liquid contact film on the porous film substrate while peeling the gas-liquid contact film from the mold. The liquid contact film may be difficult to release from the mold. In this case, it is necessary to etch the remaining film after lamination. However, in the case of superposition by simple transfer, the remaining film is on the porous film substrate side, so that there is a problem that etching cannot be performed in a subsequent process. In such a case, it is necessary to transfer it to another substrate once and turn it over, and then superimpose it on the porous film substrate. This another substrate is preferably weakly adhesive because it is necessary to re-attach the thin film peeled off from the mold to the porous film substrate.

  The gas-liquid contact film and the porous film can be used simply by being overlapped with each other, but may be heat-sealed and / or bonded with an adhesive. In the case of heat fusion, the gas-liquid contact film and the porous film substrate are melted by heating to fuse both. At this time, when the melting temperature of the material constituting the porous film substrate is lower than the melting temperature of the material constituting the gas-liquid contact film, there is less influence on the pore shape of the gas-liquid contact film during thermal fusion So it is more preferable. Examples of the heating method in the case of thermal fusion include methods such as applying a heating plate, applying hot air, and irradiating infrared rays or high frequency.

  Another aspect of the present invention is the following gas-liquid contact film module using the gas-liquid contact film and gas-liquid contact film laminate. The gas-liquid contact membrane module can be used to recover a specific gas from the mixed gas.

  The gas-liquid contact membrane module of the present invention comprises a container having an internal space separated into a first space and a second space by the gas-liquid contact membrane and / or gas-liquid contact film laminate of the present invention. The space has a gas inlet and a gas outlet from the external space, and the second space has a liquid inlet and a liquid outlet from the external space. It is also preferable to provide a cock or a valve for adjusting the flow rate or pressure at the gas inlet and / or gas outlet, liquid inlet and / or liquid outlet of the gas-liquid contact membrane module.

  The material of the container of the gas-liquid contact membrane module is not particularly limited as long as it has corrosion resistance against a liquid that dissolves a specific gas to be collected. When the object to be recovered is carbon dioxide, it is preferably made of a material having high alkali resistance. Typical examples include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy trifluoride ethylene copolymer, tetrafluoroethylene-6 fluoropropylene copolymer, Teflon (registered trademark) AF, Hyflon AD ( Fluorine resins such as (registered trademark) and Cytop (registered trademark), polystyrene, polysulfone, polyethersulfone, polyethylene, polypropylene, polyphenylene sulfide, polyarylate, and copolymers thereof are preferred for high durability.

  For example, in one mode in which the cross-sectional schematic diagram is shown in FIG. 5, the gas-liquid contact film module 11 divides the internal space of the gas-liquid contact film module into the gas inlet 12, the gas outlet 13, and the liquid inlet 14. And a liquid outlet 15. In FIG. 5, the gas-liquid contact film laminate is illustrated as a simple shape. However, in order to increase the gas-liquid contact area, a known structure such as a spiral type or a pleat type is used in such a module. Also good.

  The gas recovery method of the present invention allows a mixed gas containing a specific gas to flow from the gas inlet of the gas-liquid contact membrane module of the present invention under pressure, and the specific gas from the liquid inlet of the gas-liquid contact membrane module of the present invention. The liquid is absorbed by the liquid through the pores of the gas-liquid contact film by flowing (for example, pumping) a liquid that absorbs the gas.

The gas recovery method of the present invention can be suitably used particularly for recovering carbon dioxide. Liquid contacting through the gas-liquid contact layer in a mixed gas containing CO ₂ is to be a liquid containing a CO ₂ absorbent is preferable (hereinafter also referred to as "CO ₂ absorbing solution".). CO ₂ absorbent serves as a carrier of the CO _2, is not particularly limited as long as it can absorb the CO _2, monoethanolamine preferably known as CO ₂ absorbent, diethanolamine, A triethanolamine etc. can be mentioned. In addition, 2-amino-2-methyl-1-propanol and the like can also be used. These may be used alone, in combination of two or in combination of three or more. The liquid for containing the CO ₂ absorbent is not particularly limited, but may be water. In other words, it is preferable to use an aqueous solution containing a CO ₂ absorbent as CO ₂ absorbing solution. The absorbed carbon dioxide can be desorbed by heating, for example.

  Next, the present invention will be described more specifically based on an example in which carbon dioxide is recovered from a mixed gas containing carbon dioxide, but the present invention is not limited to such an example.

[Observation of mold and film structure]
Observation with a scanning electron microscope: A sample cut to an arbitrary size from a prepared mold and a gas-liquid contact film is fixed to a sample stage with a conductive double-sided tape, and platinum is sputtered to a thickness of about 3 nm to form a microscope sample. did. Using a high-resolution scanning electron microscope apparatus (S-3000N, manufactured by Hitachi, Ltd.), the surface and cross section of the sample were observed at an acceleration voltage of 1.0 kV and a predetermined magnification. The average value was obtained by measuring 50 locations of the diameter of the convex portion of the mold, the thickness of the mold and membrane, the pore diameter, and the pore pitch.

  Observation with an atomic force microscope: A gas-liquid contact film sample cut out to an arbitrary size from the prepared sample was fixed to a sample table with a double-sided tape to obtain an observation sample. Using an atomic force microscope (NanoScope III manufactured by Digital Instruments), the surface shape of the film was observed at a predetermined magnification using a NCHV probe manufactured by Veeco.

[Thickness]
Porous film substrate: Measured using a film thickness meter (Digital Indicator IDF-130, manufactured by Mitutoyo). Measurements were made at 10 different points to obtain an average value.
Gas-liquid contact film: The film thickness was measured by cross-sectional observation of the gas-liquid contact film with a scanning electron microscope.

[Porosity]
The volume of the pores in the measurement range of the gas-liquid contact film was measured by observing the film with a scanning electron microscope, and the porosity was calculated by the following equation (2). Here, the volume of the hole was calculated on the assumption that the diameter of the upper surface is A, the diameter of the bottom surface is B, and the height is a truncated cone shape equal to the thickness of the membrane.
Porosity (%) = (pore volume in measurement range) / volume of membrane in measurement range × 100 (2)

[CO ₂ concentration]
The CO ₂ concentration recovered to CO ₂ absorbing solution was measured by gas chromatography.

<Example 1>
Anodization was performed for 50 seconds on an aluminum plate having a purity of 99.99% at a formation voltage of 60 V using 0.3 M oxalic acid as the electrolyte. Thereafter, the film was immersed in 2% by weight phosphoric acid at 30 ° C. for 10 minutes to carry out pore size expansion treatment. This operation was repeated 5 times, and a first mold made of anodized porous alumina having tapered pores having a pore pitch of 300 nm, a pore diameter opening of 0.2 μm, and a pore depth of 0.3 μm at 200 mm both vertically and horizontally was prepared. Obtained.

  Next, the first mold was electroformed. First, surface electrode treatment was performed by nickel sputtering, and nickel electroplating was performed thereon. A second mold made of nickel was obtained by peeling the metal plating from the mold.

The obtained second mold was thoroughly washed in distilled water. A pre-prepared polysulfone (manufactured by Teijin Amoco, UDEL-P3500) in an N-methylpyrrolidone solution of 2 wt% was spin-coated on this second mold, dried at 80 ° C., and a thickness of 0.02 on the second mold. A 4 μm gas-liquid contact film precursor for CO ₂ recovery was formed. The residual film on the surface of the gas-liquid contact film precursor for CO ₂ recovery was removed by plasma etching to a thickness of about 0.15 μm.

Using a polypropylene non-woven fabric (Syntex (registered trademark) MB MO18YY manufactured by Mitsui Chemicals, Inc.) of 200 mm in both length and width as the porous film substrate, the thin film on the second mold and 160 ° C. (the heat distortion temperature of polysulfone is about 175 ° C. by melting point of the polypropylene is thermally fusing at about 160 ° C.), performs lamination with peeling and porous film substrate of the thin film from the second mold at the same time, CO ₂ for recovering consisting polysulfone onto a polypropylene nonwoven gas-liquid contact layer was obtained CO ₂ recovery gas-liquid contact film laminate are laminated. The thickness of this laminated body was 157 μm.

The gas-liquid contact membrane for CO ₂ recovery was analyzed with an electron microscope and an atomic force microscope. As a result, the porosity was 40%, and the pore diameter was 50. The minimum value was 0.18 μm, the maximum value was 0.23 μm, and the average value. The standard deviation was 0.21 μm. The average film thickness was 0.25 μm.

Then cut out the gas-liquid contact layer laminate 5 cm × 20 cm, to produce a flat sheet membrane module shown in FIG. 5, it was carried out CO ₂ recovery test. Effective membrane area was 76cm ^2.

In FIG. 5, the CO ₂ absorbing liquid is introduced from the liquid inlet 14 and is discharged from the liquid outlet 15. At this time, the pressure applied to the gas-liquid contact film laminate 11 for CO ₂ recovery is adjusted by a pressure regulating valve (not shown) on the liquid outlet 15 side. Further, a mixed gas containing CO ₂ is introduced from the gas inlet 12 and discharged from the gas outlet 13. At this time, the pressure applied to the gas-liquid contact film laminate 11 for CO ₂ recovery is adjusted by a pressure regulating valve (not shown) on the gas outlet 13 side to dissolve CO ₂ in the CO ₂ absorbing liquid.

In the module of FIG. 5, a 30 wt% monoethanolamine aqueous solution as a CO ₂ absorbing solution is applied from the liquid inlet 14 to the gas phase side and is flowed at a flow rate of 0.2 l / min. As a gas, N ₂ : CO ₂ = 9: 1 was aerated at a limit pressure that does not cause bubbling to the CO ₂ absorbent side. The pressure of the CO ₂ absorbing liquid was 0.21 kg / cm ² , the pressure of the mixed gas was 0.21 kg / cm ² , and the liquid temperature and the mixed gas temperature were 25 ° C. As a result of measuring the CO ₂ concentration of the CO ₂ absorbing solution collected from the liquid outlet 15, the CO ₂ recovery rate was 85%.

<Example 2>
A positive photoresist was applied at a thickness of 300 nm on a smooth and polished glass plate of 200 mm in both length and width to obtain a substrate with a photoresist. The light emitted from the TEM00 mode argon laser (wavelength 364 nm) is divided into two by a mirror and irradiated from two directions at an angle of 45 degrees to form an interference fringe, and the formed interference fringe is 120 degrees. The photoresist was exposed by irradiating the substrate with the photoresist from three directions at intervals. After the exposure, development was performed to remove the uncured portion, thereby obtaining a third mold.

  The projections of the third mold had a pitch of 260 nm, the diameter of the convex portion was 250 nm at the bottom, 120 nm at the top, and the height was 300 nm.

  Next, this third mold was electroformed. First, surface electrode treatment was performed by nickel sputtering. Then, electroplating of nickel was performed, and the metal plating was peeled off from the third mold, whereby the transferred first mold was obtained by inverting the uneven structure of the third mold.

  Next, as a treatment for peeling off the second electroforming, the surface of the first mold was oxidized to form a metal oxide film. Then, nickel plating was applied to the surface of the first mold as electroforming. The metal mold was peeled from the first mold to obtain a second mold. Since the second mold is produced using the first mold as a master, it can be replenished even if it is broken.

2 wt% of a pre-prepared polysulfone (manufactured by Teijin Amoco, UDEL-P3500) with 2 wt% N-methylpyrrolidone solution is spin-coated on this second mold, dried at 80 ° C., and for 0.4 μm thick CO ₂ recovery A gas-liquid contact film precursor was obtained on the second template.

Next, the fix film HG-1 (manufactured by Fuji Copian Co., Ltd.) cut out to 200 mm in both length and width was attached and peeled to release the gas-liquid contact film precursor for CO ₂ recovery from the mold.

Polypropylene nonwoven fabric (Syntex (registered trademark) MB MO18YY manufactured by Mitsui Chemicals, Inc.) as a porous film base material was cut into 200 mm both vertically and horizontally and overlapped with the gas-liquid contact film precursor for CO ₂ recovery released from the mold. . The fix film HG-1 was peeled off after heat-sealing the gas-liquid contact film precursor for CO ₂ recovery and the porous film substrate by heating at 160 ° C. The residual film on the surface of the CO ₂ recovery gas-liquid contact film precursor was removed by plasma etching to a thickness of about 0.15 μm to obtain a CO ₂ recovery gas-liquid contact film laminate. The thickness of this laminated body was 158 μm.

The gas-liquid contact film for CO ₂ recovery was analyzed with an electron microscope and an atomic force microscope. As a result, the porosity was 48%, and the pore diameter was 50. The minimum value was 0.17 μm, the maximum value was 0.24 μm, and the average value. The standard deviation was 0.22 μm. The average film thickness was 0.26 μm.

Then cut out the gas-liquid contact layer laminate 5 cm × 20 cm, to produce a flat sheet membrane module shown in FIG. 5, it was carried out the CO ₂ recovery. Effective membrane area was 76cm ^2.

In the module of FIG. 5, a 30 wt% monoethanolamine aqueous solution as a CO ₂ absorbing solution is applied from the liquid inlet 14 to the gas phase side and is flowed at a flow rate of 0.2 l / min. As a gas, N ₂ : CO ₂ = 9: 1 was aerated at a limit pressure that does not cause bubbling to the CO ₂ absorbent side. The pressure of the CO ₂ absorbing liquid was 0.22 kg / cm ² , the pressure of the mixed gas was 0.22 kg / cm ² , and the liquid temperature and the mixed gas temperature were 25 ° C. As a result of measuring the CO ₂ concentration of the CO ₂ absorbing solution collected from the liquid outlet 15, the CO ₂ recovery rate was 89%.

<Comparative Example 1>
A film-forming solution in which 19 parts by weight of polysulfone (manufactured by Teijin Amoco, UDEL-P3500), 31 parts by weight of dimethyl sulfoxide, and 19 parts by weight of polyethylene glycol (molecular weight 200) was mixed at 35 ° C. with an internal coagulation liquid (water / Dimethyl sulfoxide / polyethylene glycol = 21/50/29 parts by weight) was discharged into a double tube nozzle and coagulated in a coagulation bath at 75 ° C to produce a hollow fiber membrane. The outer diameter of the hollow fiber membrane was 1.2 mm, and the inner diameter was 1.0 mm.

  When the obtained hollow fiber was analyzed with an electron microscope and an atomic force microscope, the porosity was 40%, the pore diameter was 50, the minimum value was 0.03 μm, the maximum value was 1.25 μm, the average value was 0.21 μm, The standard deviation was 0.20. The average film thickness was 100 μm.

Using 100 hollow fibers (16) cut to a length of 1 m, a hollow fiber membrane module as shown in FIG. 6 was produced, and a CO ₂ recovery test was performed. Effective membrane area was 75 cm ^2.

In the hollow fiber membrane module of FIG. 6, a 30 wt% aqueous solution of monoethanolamine as a CO ₂ absorbing solution is applied from the liquid inlet 19 to the gas phase side and flows at a flow rate of 0.2 l / min. From the above, a gas of N ₂ : CO ₂ = 9: 1 as a mixed gas was vented to the CO ₂ absorbing liquid side at a pressure at which it was not bubbled. Pressure CO ₂ absorbing solution is 0.21 kg / cm ^2, pressure of the mixed gas is 0.11 kg / cm ^2, the liquid temperature and the gas mixture temperature was 25 ° C.. As a result of measuring the CO ₂ concentration of the CO ₂ absorbent collected from the liquid outlet 20, the CO ₂ recovery was 42%.

<Comparative example 2>
A film-forming solution in which 19 parts by weight of polysulfone (manufactured by Teijin Amoco, UDEL-P3500), 31 parts by weight of dimethyl sulfoxide, and 19 parts by weight of polyethylene glycol (molecular weight 200) was mixed on a glass plate of 25 cm × 25 cm at 50 ° C. The flat film was produced by casting with a blade, dipping in a coagulation liquid at 35 ° C. (water / dimethyl sulfoxide / polyethylene glycol = 21/50/29 parts by weight), and coagulating in a coagulation bath at 75 ° C.

  When the obtained flat film was analyzed with an electron microscope and an atomic force microscope, the porosity was 40%, the pore diameter was 50, the minimum value was 0.03 μm, the maximum value was 1.23 μm, the average value was 0.20 μm, The standard deviation was 0.19. The average film thickness was 150 μm.

The size of the flat membrane was 5 cm × 20 cm. Using this flat membrane (21), a flat membrane module as shown in FIG. 7 was produced, and a CO ₂ recovery test was conducted. Effective membrane area was 76cm ^2.

In the flat membrane module of FIG. 7, a 30 wt% monoethanolamine aqueous solution as a CO ₂ absorbing solution is applied from the liquid inlet 24 to a limit pressure that does not leak to the gas phase side, and is flowed at a flow rate of 0.2 l / min. As a mixed gas, a gas of N ₂ : CO ₂ = 9: 1 was aerated at a limit pressure that does not cause bubbling to the CO ₂ absorbent side. The pressure of the CO ₂ absorbing liquid was 0.20 kg / cm ² , the pressure of the mixed gas was 0.10 kg / cm ² , and the liquid temperature and the mixed gas temperature were 25 ° C. As a result of measuring the CO ₂ concentration of the CO ₂ absorbent collected from the liquid outlet 25, the CO ₂ recovery rate was 38%.

The gas-liquid contact membrane of the present invention can be suitably used in the field of separation and recovery of mixed gas, particularly CO ₂ recovery.

DESCRIPTION OF SYMBOLS 1 2nd casting_mold | template by a 1st manufacturing method 2 Aluminum 3 Anodized porous alumina 4 Pore 5 Gas-liquid contact film 6 Porous film base material 7 Substrate 8 Convex part which consists of a taper-shaped protrusion 8a Top part of convex part 8b The bottom part of the convex part 9 The third mold 10 by the second manufacturing method 10 The first mold 11 by the second manufacturing method 11 The gas-liquid contact film laminated body (flat film) for CO ₂ recovery of the module used in Examples 1 and 2 )
12 Gas inlet of the module used in Examples 1 and 2 13 Gas outlet of the module used in Examples 1 and 2 14 Liquid inlet of the module used in Examples 1 and 2 15 of the module used in Examples 1 and 2 Liquid outlet 16 Gas-liquid contact membrane (hollow fiber membrane) for CO ₂ recovery of the module used in Comparative Example 1
17 Gas inlet of the module used in Comparative Example 1 18 Gas outlet of the module used in Comparative Example 1 19 Liquid inlet of the module used in Comparative Example 1 20 Liquid outlet of the module used in Comparative Example 1 21 Used in Comparative Example 2 Gas-liquid contact membrane (flat membrane) for CO ₂ recovery
22 Gas inlet of the module used in Comparative Example 2 23 Gas outlet of the module used in Comparative Example 2 24 Liquid inlet of the module used in Comparative Example 2 25 Liquid outlet of the module used in Comparative Example 2

Claims (10)

  A gas-liquid contact membrane having pores, wherein the pore pitch of the pores is 30 to 1000 nm, the pore diameter of the pores is 10 to 300 nm, and the thickness of the gas-liquid contact membrane is 30 to A gas-liquid contact membrane having a thickness of 1000 nm and a standard deviation in the pore size distribution of the pores of 30% or less of the average value. 2. The method according to claim 1, comprising the steps of: transferring the irregularities of the first mold having recesses made of pores to a second mold; and transferring the irregularities of the second template to a film made of a polymer. A method for producing a gas-liquid contact film.   The manufacturing method of Claim 2 with which the 1st casting_mold | template which has the recessed part which consists of the said pore is produced by anodizing an aluminum plate. A step of transferring the irregularities of the third mold having projections made of protrusions to the first mold;
2. The production of the gas-liquid contact film according to claim 1, comprising the steps of: transferring the irregularities of the first template to a second template; and transferring the irregularities of the second template to a film made of a polymer. Method.   5. The manufacturing method according to claim 4, wherein the third mold having the convex portion formed of the protrusion is produced by developing the photoresist layer laminated on the substrate by interference exposure.   A gas-liquid contact film laminate obtained by laminating the gas-liquid contact film according to claim 1 and a porous film substrate. A step of laminating the gas-liquid contact film according to claim 1 and a porous film substrate, and a step of fusing the gas-liquid contact film and / or the porous film substrate by heating and fusing them together The manufacturing method of the gas-liquid contact film | membrane laminated body containing this.   The gas-liquid contact film according to claim 1 or the gas-liquid contact film laminate according to claim 6 comprises a container in which the internal space is separated into a first space and a second space, A gas-liquid contact membrane module having a gas inlet and a gas outlet from a space and having a liquid inlet and a liquid outlet from an external space in a second space.   9. A mixed gas containing a specific gas flows from the gas inlet to the gas outlet of the gas-liquid contact membrane module according to claim 8, and a liquid that absorbs the specific gas flows from the liquid inlet to the liquid outlet. A gas recovery method including the step of causing the liquid to absorb the specific gas.   The method according to claim 9, wherein the specific gas is carbon dioxide.

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