JPS59199001A - Composite membrane for gas separation and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a polymeric composite membrane for separating hydrogen from a gaseous mixture by laminating polymeric thin films, having two kinds of intrinsic separation factors for a gaseous mixture of hydrogen and nitrogen, in a specified ratio on a polymer and an inorganic material compounding porous membrane having specified porosity. CONSTITUTION:A polymeric soln. A, consisting of a polysulfonic or a polyetheric resin etc. and having >=20 intrinsic separation factor for a gaseous mixture of hydrogen and nitrogen, and a polymeric soln. B, consisting of a silicone or a phosphazene polymer etc. and having the permeability coefficient of hydrogen at least ten times larger than that of the polymer in said soln. A, are coated on a polymer and an inorganic material compounding porous membrane, contg. 10-80wt% granular inorganic material and having 0.1mum mean pore size and porosity in the 30-80% range, and dried. In addition, the ratio of the layer thickness of the thin film consisting of the soln. B to that of the resistance layer consisting of the soln. A is regulated to >=5, and both films are laminated to manufacture the composite membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a composite membrane for separation. More specifically, the present invention relates to a polymer composite membrane for separating at least hydrogen from a gas mixture containing hydrogen.

The selective separation of specific gases from a gas mixture using membranes, especially polymer membranes, is highly efficient and has high industrial value as an energy-saving and labor-saving separation method. This is well known to those skilled in the art.

In particular, there is a strong interest in hydrogen separation, and the oil refining industry has applications such as hydrogen recovery from purge gas generated in hydrogenation plants, hydrogen separation and purification from hydrogen generated in reformers, and carbon monoxide mixed gas. It is considered. In addition, applications are being considered for hydrogen recovery from purge gas in ammonia synthesis plants, methanol synthesis plants, etc., and for adjusting the hydrogen/carbon monoxide molar ratio in oxo synthesis gas.

Regarding the application of polymer membranes to gas separation, much research has been conducted on dense homogeneous membranes, and gas permeation through polymer membranes is based on the dissolution of gas molecules into polymeric materials and the dissolution of dissolved gases. It is thought to be expressed as the product of the diffusion of molecules within a polymeric material.

Each gas has a unique permeability coefficient for a specific polymer membrane based on the interaction between the two, and when a mixed gas is applied, the polymer membrane has a unique permeability coefficient due to the difference in the permeability coefficient of the individual gases. The membrane has a unique separation performance called the separation coefficient of the membrane.

Therefore, the separation coefficient of gas through a specific polymer membrane is constant regardless of the thickness of the membrane, and the membrane permeation rate of gas increases in inverse proportion to the membrane thickness.

In order for the selective separation of gases using a polymer separation membrane to be performed with sufficient efficiency, in other words, in order to make commercial implementation possible, it is necessary to It must not only be able to withstand high temperatures, but also have a desired separation coefficient and a sufficiently high permeation rate for the gas to be separated.

Conventionally, two main proposals have been made for gas separation membranes. One is to form a polymer having a desired separation coefficient as an ultrathin film on a suitable porous support membrane. Practically, in order to significantly increase the gas permeation rate, the ultrathin film must have a thickness of 1 μm or less, preferably 0.5 μm or less. It is not easy to form such an ultra-thin film uniformly and firmly adhered to a porous support without defects such as pinholes, the manufacturing technology is extremely complex, and the manufacturing cost is extremely high, making it difficult to manufacture on an industrial scale. Production is difficult.

Another proposal is disclosed in Japanese Patent Application Laid-Open No. 53-86684. Using a polymer having a high separation coefficient for a certain gas, the gas permeability is the same as that of a dense homogeneous ultrathin film of the polymer. To form a porous film having a high speed,
The micropores on one side are often coated with another polymer that has a low separation coefficient but a higher gas permeability. The porous membrane in this proposal must be a so-called "asymmetric membrane," which has extremely fine pores in a very thin layer on one surface and larger pores extending from the inside to the other surface. figure,
The production of such asymmetric membranes requires wet casting from a solution of polymer dissolved in a solvent, and the production of such asymmetric membranes requires the use of large amounts of special solvents and the manufacturing process required to obtain the desired membrane structure. It requires delicate adjustment of conditions, and its industrial production is complicated and expensive.

Furthermore, there is a porous gas separation membrane that can be used as a gas separation membrane, has separation performance at a relatively high temperature for the gas to be separated, has an appropriate solvent, and can form an asymmetric membrane by a wet casting method. The number of polymers that allow the membrane to maintain the strength and other physical properties necessary for a gas separation membrane is extremely limited, and the practical value of this proposal is greatly restricted.

The present inventors have arrived at the present invention as a result of repeated research on a practically significant composite membrane for gas separation.

An object of the present invention is to provide a composite membrane for gas separation that has sufficient durability under temperature, pressure, and other conditions of reliable use, and has high separation performance and high gas permeation rate. Another object is to provide a composite membrane for gas separation that is particularly suitable for separating hydrogen gas.

To explain the gas separation membrane of the present invention, the gas separation membrane of the present invention contains 10% by weight or more and less than 80% by weight of inorganic fine particles, has an average pore diameter of 01 μm or less, and has a porosity of 30% to 80%.
A thin layer (1) of a polymer having an inherent separation coefficient of 20 or more for a hydrogen/nitrogen mixture gas on a porous membrane containing a polymer and an inorganic substance in the range of 1
) with a permeability coefficient at least 10 times greater than that of the polymer forming the polymer (ID) is laminated and the ratio of the respective average layer thicknesses of layer (1) and layer (11) [(II) /(1)
) is 5 or more.

To explain the present invention in more detail, the polymer/inorganic compound porous membrane referred to in the present invention refers to inorganic fine particles of 10% to less than 80% by weight, preferably 20% to less than 60% by weight, which are generally used as a molding material. It is a porous membrane in which the particles are dispersed in a polymer, and fine communicating pores are formed mainly at the interface between the inorganic fine particles and the polymer and/or between the particles of the inorganic fine particles, forming a network structure. Such a polymer/inorganic composite porous membrane is produced by mixing a polymer and inorganic fine particles, molding it into a desired shape such as a sheet, film, or hollow fiber using a known polymer melt molding method, and then subjecting it to appropriate temperature conditions. A method of stretching the polymer to a certain extent, or mixing the polymer, inorganic fine particles, and a suitable organic liquid, and using a known polymer melt molding method at °C to form a desired shape such as a sheet, film, or hollow fiber. After molding, the molded product or
It is manufactured by a method such as extracting and removing an organic liquid from a liquid.

An example of an advantageous polymer/inorganic compound porous membrane used in the present invention and a method for producing the same is disclosed in JP-A-52-70988 and JP-A-52-156,776.

In the polymer/inorganic compound porous membrane according to the present invention, if the amount of inorganic fine particles is less than 10% by weight, the plasticizer is large and even if it is uniformly dispersed in the polymer, it is difficult to form continuous pores. , it does not result in a practical porous membrane.

Furthermore, if the amount of inorganic fine particles is 80% by weight or more, the strength of the membrane will be low and it will not be possible to obtain a practical porous membrane.

Examples of inorganic fine particles used in the present invention include carbon black, silicon oxide, calcium silicate, aluminum silicate, aluminum oxide, titanium oxide, kaolin clay, calcium carbonate, magnesium carbonate, carbon black, talc, barium sulfate, Mica, asbestos, etc. may be used alone, or a mixture of two or more thereof may be used. Furthermore, the particle shape of the inorganic fine particles used in the present invention is not particularly limited;
Average particle size 0.005-1 μm, specific surface area 30-800
Fine particles of m2/liter or porous particles are preferable when obtaining a porous membrane containing a polymer and an inorganic material that is uniform and has excellent performance.

The average pore diameter of the polymer/inorganic compound porous membrane in the present invention is required to be 0.1 μm or less.

If the average pore diameter is larger than 0.1 μm, when trying to form the thin layer (1) of the polymer on the porous membrane, the polymer may penetrate into the pores of the porous membrane. It becomes difficult to embed and form the desired thin layer. therefore,
The average pore diameter of the porous membrane is 0.01 μm or less, preferably 0.07 μm.
It should be less than m.

Furthermore, it is essential that the porous membrane has a porosity in the range of 30% to 80%. If the porosity is less than 30%, the gas permeation rate of the porous membrane itself is low and it is not practical as a support membrane for gas separation.

In addition, if the porosity is greater than 80%, the membrane strength will be low and it will be difficult to make a practical porous membrane. The porosity of the porous membrane used in the present invention is 30 to 80%, more preferably 40 to 65%.
It is.

The polymers that make up the polymer/inorganic compound porous membrane are:
For example, but not limited to, ethylene,
Polyolefin resins such as propylene, butene-1, etc., or copolymers containing one or more of these as main components, vinyl fluoride, vinylidene fluoride, trifluoroethylene, or tetrafluoride. Fluorine-based resins consisting of polymers such as fluorinated ethylene or copolymers containing these as constituents, polyester-based fats such as polyethylene terephthalate and polybutylene terephthalate, polyamide-based resins, polystyrene-based resins, and polychlorinated resins. Vinyl and many other extrudable thermoplastic resins, which can be selected singly or in mixtures of two or more resins.

Furthermore, it is also possible to treat these resins after molding to add halogen groups such as fluorine, chlorine, and bromine, and functional groups such as hydroxyl groups, alkoxy groups, acyl groups, amide groups, and sulfone groups. .

Particularly preferred examples of polymers for producing the polymer/inorganic compound porous membrane of the present invention include polyolefin resins and fluororesins. A variety of polyethylenes, polypropylenes, and copolymers of them, ranging from low-density polyethylene to high-density polyethylene, have excellent strength, chemical resistance, flexibility, etc., and are easy to mix and knead with inorganic fine particles. Sheets, films, hollow fibers, etc. can be formed very easily from the resulting mixture using ordinary molding methods.Fluororesins have superior chemical resistance, strength, and heat resistance compared to polyolefin resins. Examples of fluororesins include tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, polytrifluoroethylene resin, and tetrafluoroethylene-ethylene copolymer. and polyvinylidene fluoride resin.

The polymer/inorganic compound porous membrane according to the present invention has a network structure of pores formed by fine voids with an average pore size of 01 μm or less, preferably 0.07 μm or less, at the interface between the polymer and inorganic fine particles in the membrane and/or between the inorganic fine particles. gender is given.

In the present invention, it is essential to use a porous membrane having such a fine average pore diameter.

Furthermore, the importance of using a polymer/inorganic compound porous membrane in the present invention will be described below.

As a method for forming a thin layer (1) of a polymer on a porous support membrane, a solution in which the polymer is dissolved in an appropriate solvent is thinly coated (laminated) on the porous membrane using a known method. After that, it is practical to remove the solvent by evaporation. The polymer/inorganic compound porous membrane according to the present invention becomes extremely wettable with the polymer solution due to the presence of inorganic fine particles.
- This makes it easy to coat the polymer solution thereon with a thin and relatively constant thickness. Furthermore, since the pores of the polymer/inorganic compound porous membrane have a fine network structure consisting mainly of gaps between inorganic fine particles, the solvent in the coated polymer solution not only evaporates from the surface; It penetrates extremely quickly through the network structure of the gaps between the inorganic particles and is also evaporated and removed from the back surface. As a result, the formed polymer thin film becomes an extremely thin film that has a relatively uniform thickness with little penetration into the pores and is also homogeneous in the thickness direction. Furthermore, the anchor effect between the inorganic fine particles and the coating layer improves the adhesion between the support membrane and the gas separation active thin membrane, or the porous membrane as a support membrane can withstand pressure under harsh operating conditions such as temperature and pressure. Practical use as a gas separation membrane, such as improved density, can improve important performance.

Next, the separation coefficient of hydrogen and nitrogen mixed gas in the present invention is 2.
Various resins can be used as the polymer thin layer (1) having an inherent separation performance of 0 or more. Typical examples include polysulfone resins, cellulose acetate, polyvinyl fluoride, polyester resins represented by polyethylene phthalate, polyamideimide resins, aliphatic or aromatic polyamide resins, and polycarbonate resins. , polyimide resins, polyphenylene ether resins, butadiene-acrylonitrile copolymers, etc. Among these, polysulfone resins and polyphenylene ether resins are preferred because they are easy to form a thin film during solution coating. Become.

Among the polysulfones used are repeating structural units (wherein and R1 are the same or different and contain an aliphatic or aromatic hydrocarbyl-containing moiety, e.g., 1 to about 40 carbon atoms). The sulfur in the sulfonyl group is bonded to an aliphatic or aromatic carbon atom) and has a polymeric backbone containing 10,0
It is preferable that it has an average molecular weight of 0.00 or more. When the polysulfone is not cross-linked, the polysulfone generally has a molecular weight of about 500,000 or less.

R and R' may be substituted by carbon-carbon bonds or by various bonding groups such as 0 0 0 0 II II II 11-0-1
-S-1-C-1-C-N-1-N-C-N-1-0-
The bond can be made through a C-11 HHH group or the like. Particularly advantageous polysulfones are those in which at least one of R and R1 includes an aromatic hydrocarbyl-containing moiety, and the sulfonyl moiety is bonded to at least one aromatic carbon atom.

Common aromatic hydrocarbyl-containing moieties include phenylene and substituted phenylene moieties, bisphenyl and substituted bisphenyl moieties, bisphenylmethane and substituted bisphenylmethane moieties having a nucleus of formula Substituted and unsubstituted bisphenyl ethers (X is oxygen or sulfur) and others are included. In the above bisphenylmethane and bisphenyl ether moieties, R,, -几, 0 may be the same or different and the structure lX! ! [wherein X1 and X2 may be the same or different and are hydrogen or halogen (e.g. fluorine, chlorine and bromine), p is O or an integer such as from 1 to about 6, and 2 is hydrogen, (e.g. fluorine, chlorine and bromine), +Y→-R11 (where q is 0 or 1
, Y is 10-1-S-100 1-5S-1-QO- or -C-, and R11
is hydrogen, substituted or unsubstituted alkyl containing, for example, 1 to about 8 Ω carbon atoms, or monocyclic or bicyclic substituted or unsubstituted aryl containing, for example, about 6 to 15 carbon atoms. ), heterocycles having a heteroatom that is at least one of nitrogen, oxygen and sulfur and being monocyclic or bicyclic having about 5 to 15 ring atoms, sulfate and sulfono, especially lower alkyl or monocyclic or bicyclic aryl.
1 and sulfono, phosphorus-containing moieties such as phosphines and phosphates and phosphonos, especially those containing lower alkyl or monocyclic or bicyclic aryl, primary, secondary, tertiary and Amines containing quaternary amines (secondary, tertiary and quaternary amines often contain lower alkyl or monocyclic or bicyclic aryl moieties), thioureyl, thiouryl, guanidyl , trialkylsilyl, trialkylstanyl, dialkylstivinyl, etc.]; Substituents on the phenyl group of bisphenylmethane and bisphenyl ether moieties are often in the ortho position. That is, R7 to RIO are hydrogen. Polysulfones with aromatic hydrocarbyl-containing moieties generally have good thermal stability, are resistant to attack by chemical reagents, and have an excellent combination of toughness and flexibility. Useful polysulfones are manufactured by Union Carbide, such as Needel P-1700J and Needel P-3500
It is sold under the product name J. Both of these products have linear chains of the general formula (where n, representing the degree of polymerization, is about 50 to 8o). Poly(arylene ether) sulfones are also advantageous.

Also useful are polyether sulfones having the structure available from ICI under the trade name JlooPJ.

Still other useful polysulfones include, for example, cross-linked,
It can be produced by modifying the polymer by grafting, quaternization, etc.

BoIJ phenylene ether can be expressed by the following general formula (wherein R1 and R8 independently represent an alkyl group having 1 to 4 carbon atoms or a halogen atom, and R2 represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or a halogen atom). , n is 50-3
0o, preferably 6-280, more preferably 70-2
is an integer in the range of 50. ) may be preferably used.

A typical example of polyphenylene ether represented by the above general formula is poly(2,6-dimethylphenylene-1,4
-ether), poly(2,6-diethylphenylene-1
, 4-ether), poly(2-methyl-6-ethylphenylene-1,4-ether), poly(2-methyl-6-
chlorophenylene-1,4-ether), poly(2,6
-cyclophenylene-1,4-ether), poly(2
, 6-di-n-propylphenylene-1,4-ether), poly(2-methyl-6-n-butylphenylene-1)
,4-ether), poly(2-methyl-6-7"romphenylene-1,4-ether), poly(2,3,6-
trimeral phenol), etc.

The above-mentioned polymer layer CI) is a part that plays a major role in the separation performance of the composite membrane for gas separation of the present invention, and is required to have an inherent separation performance with a hydrogen/nitrogen gas separation coefficient of 20 or more. Therefore, if the performance is lower than this, it is impossible to obtain a separation membrane with practical separation performance. In addition, the polymer layer (
1) does not necessarily have to be a homogeneous membrane with a uniform thickness; as long as the average thickness is 1 μm or less, a separation membrane with a practical permeation rate can be obtained. That is, the thin polymer layer (1) may have an average thickness of 1 μm or less, preferably 0.5 μm or less, and more preferably 0.2 μm or less.
m or less, in which case it is acceptable for pinholes and other thin film defects to exist partially. Although it is difficult to quantify the allowable degree of defects, it has been empirically shown that the thin layer of polymer (1) is The air permeation rate of the laminated membrane formed on the porous membrane is adjusted to be less than 1150°C, preferably about 1/100°C.

If the air permeation rate of the laminated membrane is greater than 1150, the thin layer (1,) has so many defects that a practical composite membrane for gas separation cannot be obtained.

Next, in the present invention, the polymer used for the thin polymer layer (II) whose hydrogen permeability coefficient is at least 10 times larger than that of the polymer forming the thin polymer layer (I) is, for example, silicon. Examples include phosphazene-based polymers and phosphazene-based polymers. In order to obtain a composite membrane for gas separation with excellent practical performance, the hydrogen permeability coefficient of the polymer forming the thin layer (11) is 10'c1rL3(S T P ) -cx/
It is desirable that it is cm2·sec, cr/LHg or more. Examples of silicon-based polymers include polydimethylsiloxane, or silicone resins whose methyl groups are partially substituted with trifluoroglobyl groups, cyanopropyl groups, phenyl groups, or vinyl groups.

They may be used as is or may be crosslinked and cured after film formation. Alternatively, a layer can be formed by three-dimensionally cross-linking a hydroxyl-terminated dimethylsiloxane oligomer in the presence of water using a trifunctional silane such as methylacetoxysilane, methylalkoxysilane, methylaminosilane or methylhydroxylaminosilane, or a layer can be formed using tetraethoxysilane. It is also possible to three-dimensionally crosslink an alkoxysilane such as or methyltriethoxysilane and a hydroxyl-terminated siloxane oligomer in the presence of an amine, dibutyltinlaurate, or alkyl titanate.

Phosphazene-based polymers include polydiphenoxyphosphazene, polytrifluoroethoxyphosphazene, polybisethoxyphosphazene, and poly-1-bismethylaminophosphazene.

Phosphazene-based polymers have slightly poorer thin film forming properties than silicon-based polymers and lack manufacturing stability, so silicon-based polymers are particularly suitable for the polymer layer (n).

The silicon-based polymer is preferably cross-linked three-dimensionally, which improves the strength of the film and makes it easier to handle.The thickness of the resin layer is 0.5 to 100 μm.
It is preferable that the temperature is m°C. The thickness of this layer is 0.5μm
Below, ゛ is the thickness ratio with the thin polymer layer (1),
Sufficient gas separation performance cannot be exhibited, and if the thickness is 100 μm or more, it becomes difficult to obtain a practical gas permeation rate.

In the present invention, the ratio of the respective average thicknesses of the thin polymer layer (1) and the thin polymer layer (11) [(n)/(1)':
It is necessary that l be 5 or more. The polymer layer (n) adjusts the gas permeation rate, in other words, provides resistance to gas permeation, and plays a role in fully demonstrating the gas separation function of the thin polymer layer (I). . Thin layer of polymer (II
) becomes thinner and the thickness ratio [(II)/(I) ) becomes less than 5, the resistance becomes too small and the separation performance of the resulting gas separation membrane falls below the practical limit. Therefore, the average thickness ratio [(II)/(1):] of the polymer layer (1) and the polymer layer (■) in the present invention is at least 5.
or more, preferably 10 or more.

The composite membrane for gas separation of the present invention is a porous membrane containing a polymer and an inorganic substance/a thin layer of a polymer (I)/a thin layer of a polymer (II), or a porous membrane containing a polymer and an inorganic substance/a thin layer of a polymer ( (2)/A thin layer of polymer is laminated in a structure similar to (1).

The polymer/inorganic compound porous membrane is a supporting layer as a composite membrane for gas separation, and the thin polymer layer (1) is essentially an active layer that has gas separation performance, and the thin polymer layer (n) is a gas permeation resistant layer having the function of allowing the thin layer (1) to exhibit sufficient separation performance. As an embodiment of the present invention, a layer structure of polymer/inorganic composite porous membrane/polymer thin layer (I)/polymer thin layer (n) is more preferable. This is because, with such a layer configuration, the thin polymer layer (II) functions not only as the resistance layer but also as a protective layer for the thinner polymer thin layer (1).

Next, an example of the method for manufacturing the composite membrane for gas separation of the present invention will be explained. However, the method for producing a composite membrane of the present invention is not particularly limited to this example, and it is possible to obtain a preferable separation membrane by changing the conditions as appropriate. The polymer/inorganic compound porous membrane containing 10% by weight or more and less than 80% by weight of inorganic fine particles in the present invention can be obtained by using various conventionally known methods for producing porous membranes, but preferably by the present applicant. The method for producing a porous membrane proposed in Japanese Patent Application Laid-Open No. 52-156776 is used.

In the present invention, the type of polymer forming the polymer/inorganic compound porous membrane is not particularly limited, as described above. Next, as a method for providing the thin polymer layers (1) and (II) on one side of the porous polymer membrane, it is possible to coat the surface of the polymer/inorganic compound porous membrane with the polymer in a solution state. I like it.

Examples of coating methods include spray coating,
Brush coating, roller coating and dipping methods (dipping)
Any known method can be applied. The solvent for the polymer to be used is appropriately selected from organic compounds that are good solvents for each polymer.

Examples of solvents used for the polymers forming the thin polymer layer (1), such as polysulfone resins, include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethylsulfoxide. C. and chlorinated hydrocarbons can be used alone or in combination, and in the case of polyphenylene oxide resin, for example, chlorinated hydrocarbons can be used. The concentration of the solution depends on the required thickness of the layer and can be selected as appropriate, but the type of solvent and coating temperature conditions are adjusted so that the viscosity of the solution is at least 10 centipoise or more, preferably 20 centipoise or more. It is important to set the After coating the polymer layer (1), it is preferable to completely remove the solvent by heating it to near the boiling point of the solvent used for coating, but there are no necessary steps.
.

Next, as a polymer solvent for forming the polymer thin layer (Ili), for example, various organic compounds can be applied to silicone resin, but a typical example is toluene. and hydrocarbon compounds such as xylene. The concentration of the coating solution varies depending on the required layer thickness, but the viscosity of the solution is preferably 20 centipoise or more, preferably 30 centipoise or more, in order to form a uniform film. In addition, as the polymer layer (II) used here, the silicone resin layer is preferably three-dimensionally crosslinked, and in the case of a moisture-curable silicone resin, 20"C to 50"C190 to 100% When using catalysts such as amines and dibutyltin laurate, treatment at 0.5 to 10 hours at relative humidity can be performed at 2 °C.
By treating at 0 to 50'C for 1 to 5 hours,
For peroxide-curing silicone resins, for example, benzoyl peroxide or diwalnut peroxide is used to obtain a three-dimensionally crosslinked silicone resin layer by treating at 100 to 20°C for 05 to 2 hours. be able to. Regarding phosphazene polymers, there are several types, but for polybisethoxyphosphazene, benzene, ether, ketone, or alcohol is preferable, and for polybistrifluoroethoxyphosphazene, ketone or ester is preferable as a solvent. The concentration of the coating solution can be changed depending on the required thickness of the film, but the viscosity of the solution is preferably 20 centipoise or more, preferably 30 centipoise or more to form a uniform film.

Furthermore, in order to strengthen the adhesion between the polymer layer (1) and the polymer layer (II), the polymer layer is made of a polyfunctional silicone oligomer or a polyfunctional silicone monomer with a relatively low molecular weight. After treating the surface of (1) or the polymer layer (II), the polymer layer (I) or the polymer layer coating can be provided.

The above manufacturing method can be applied without any problem even if the polymer/inorganic compound porous membrane is in the form of a flat membrane, a tube, or a hollow fiber.

The composite membrane for gas separation in the form of a flat membrane, a tube, or a hollow fiber thus obtained is put to practical use by manufacturing a separation module of a known type according to each form.

The features of the present invention are summarized below.

In the present invention, as described above, a porous membrane containing a polymer and an inorganic material is used as a support for the gas separation active thin membrane. Without going through extremely complicated and cumbersome processes, you can simply coat a porous membrane containing polymers and inorganic materials with a solution containing the components that will form a thin layer (1) with excellent separation performance or a resistive layer (11) and dry it. Composite membranes can be easily obtained.

(11) In the present invention, instead of forming a porous membrane using a polymer having gas separation activity as in JP-A-53-86684, gas separation is performed on a relatively inexpensive microporous membrane that is easily manufactured separately. Since an active thin film is formed, it is advantageous in terms of raw material cost.

(iii) The presence of inorganic fine particles makes the polymer/inorganic compound porous membrane extremely wettable by the polymer solution, so it can be coated with the polymer solution in a thin and relatively constant thickness; Therefore, the gas separation active thin film layer of the composite membrane obtained as a final product is very thin and uniform.

Gv) Due to the presence of inorganic fine particles in the porous membrane, the solvent of the coated polymer solution can easily penetrate into the pores selectively, and there is little intrusion into the pores of the thin polymer membrane.
This A1 also makes it easier to form an extremely thin film layer with a uniform thickness.

() The thin film layer formed by coating the inorganic fine particles has good wettability with the polymer, and the adhesion between the support film (porous membrane) and the thin film is improved due to the anchor effect.0 (VD Porous where no inorganic fine particles are present) For membranes, high temperature and
Under high pressure, it is likely to be crushed under pressure, causing problems in consolidation resistance, but in the present invention, the inorganic fine particles work to suppress deformation of the polymer portion, improving consolidation resistance.

(vl) Since the composite membrane of the present invention has a thin and uniform gas separation active membrane layer, it has a large separation coefficient and permeation rate, and is of great industrial value.

EXAMPLES Hereinafter, the content of the present invention will be explained in more detail with reference to Examples, but the content of the present invention is not limited thereby. In addition, in the examples, a hydrogen/nitrogen mixture gas is mainly used as a model of a gas mixture, but oxygen, carbon oxide, carbon dioxide, etc. may be used instead of nitrogen, or a mixture of the above gases including nitrogen may be used. It is well known to those skilled in the art that almost the same results as in the case of separation of a hydrogen/nitrogen gas mixture can be obtained even when the temperature is used.

Definitions of main terms used in the present invention are as follows.

Gas permeation rate Ccx3(STP)/CTL2-sec
・cgiHg] Gas permeation rate is ASTM D-1
The measurement was carried out by the method of No. 434. The permeation rate of a given membrane is the amount of gas that passes through the membrane per second per second, with a partial pressure drop of mercury of ICll1 between the gas supply side and the permeate side, at room temperature and room temperature. This is a value converted to volume under pressure conditions.

Gas Separation Coefficient (α) For example, the separation coefficient of hydrogen gas with respect to nitrogen gas is a value obtained by dividing the hydrogen gas permeation rate of a given membrane by the nitrogen permeation rate of the membrane.

This is a numerical value calculated using the following formula.

Note that the pore volume is calculated using the following formula.

Pore volume - water content weight - bone dry weight (ml/9) average pore diameter (
d) It is a numerical value calculated by the following formula from the value of specific surface area (s) determined by the BE'l'' adsorption method.

2■ d-1 (μm) ■, pore volume (ml/liter) S: specific surface area (m2/liter) average layer thickness of thin film <1) weight (w) of a support of a certain area (S), The weight of the polymer membrane (W
) is the numerical value calculated by measuring.

-w l = -X ], 0' (μm) S ・ρ S: Area of support (C7rL2) ° W: Weight of support and coating material (g) W:
Weight of support (1 ρ: Density of coating material (cm3/9)) Example 1 23% by weight of silicon oxide [Aerosil+200 (trade name), specific surface area 175 m2/9, average particle size 16 mμ] and dioctyl phthalate (DOP) ) 54% by weight was mixed in a Henschel mixer, and this was mixed with high density polyethylene [
5untec S-360 (trade name)] 23% by weight of resin was added and mixed again using a Henschel mixer.

The mixture was mixed in a 30 m/mφ twin-screw extruder and made into pellets. The pellets were molded using a film manufacturing device equipped with a 30 m/mφ twin screw extruder and a 420 m/m wide T-die. At this time, the extrusion amount was 12 kg/nr, the take-up speed was 2 m/ini□1, and the resin pressure was 70 and ν height 2.

The formed film is 1. , ], , 1. -) DOP was extracted by immersion in dichloroethane (chlorocene) for 5 minutes. The thickness of the resulting polymer/inorganic compound porous membrane was Q, 135 m/m, the porosity was 58%, and the composition of the porous membrane was approximately 50% by weight of polyethylene resin, approximately 50% by weight of finely divided silicic acid, and porous membrane. The average pore diameter was 0.02 μm. Next, take a part of the porous membrane at ℃ and add 10% by weight of polysulfone (Union Carby) Udel P-1,
700 (trade name): Unless otherwise specified, Needel P-1,700 is used as the polysulfone in the Examples. ]N,N-dimethylacetamide solution at 20'
The porous membrane was coated with coach-in blonde under the conditions of C, and then heated at 90° C. for 10 minutes to remove the solvent.

The average thickness of this layer was 0.07 μm. Further, on the polysulfone layer, 200 cp of methyltrialkoxysilane and hydroxyl group-terminated dimethylsiloxane oligomer
A toluene solution of S was coated with coach-in-blonde at 20'C to form a 20 μm homogeneous layer of silicon. Furthermore, the composite membrane is 50″C110
A three-dimensional crosslinking reaction was carried out under the condition of 0% RH for 1 hour to obtain a composite membrane for gas separation.

The separation performance of hydrogen gas and nitrogen gas was measured using the above composite membrane, and the results are shown in Table 1. It can be seen that the permeation rate of the polymer/inorganic compound porous membrane is much higher than the permeation rate of the dense polysulfone layer and silicone resin layer, and that the resistance to gas permeation is small. The separation performance of the composite membrane between hydrogen gas and nitrogen gas is much larger than the separation coefficient of the polymer/inorganic compound porous membrane or the silicone resin layer, and is close to the inherent separation performance of polysulfone. Furthermore, since a composite membrane consisting only of a porous membrane containing a polymer and an inorganic substance and a dense polysulfone layer has almost no separation performance, it is necessary to use a porous membrane containing a polymer and an inorganic substance as a support, such as the separation function of polysulfone, as in the present invention. It is clear that an excellent composite membrane for gas separation, in particular a composite membrane for hydrogen separation, can be obtained by the combination of a thin layer of a resin containing a silicone material and a resin layer that acts as a resistance layer that adjusts the permeation rate of gases such as silicon. .

Table 1 1) Calculated value of polysulfone from the following values Hydrogen gas permeability coefficient 1.3X10' cIrL3 (S T P ) ""l/cln" H:
: a (: ・鑞■(, g nitrogen gas permeability coefficient ],,
8X10'' Examples 2 to 4 The same method as in Example 1 except that the fine powder silicon oxide content of the inorganic-containing polymer/inorganic compound porous membrane was varied from 30% by weight to 65% by weight. A composite membrane for gas separation was obtained.

Next, the separation performance of hydrogen gas and nitrogen gas was measured using the above composite membrane, and the results are shown in Table 2.

It was confirmed that the hydrogen permeation rates of the above composite membranes all reached practical levels, and the separation coefficients were also excellent at °C.

Table 2 Examples 5 to 8 In Example 1, the thickness of the 200 cps toluene solution of methyltrialkoxysilane and hydroxyl-terminated dimethylsiloxane oligomer (r) to be coated on the polysulfone layer was changed, and the thickness of the silicone resin homogeneous layer was increased by 1. ，
All examples except for 1.0, 50.80μ units]
The same operation as above was performed to obtain a composite membrane for gas separation.

Next, the permeation rates of hydrogen gas and nitrogen gas were measured using the above composite membrane, and the results are shown in Table 3.

It can be seen that the separation performance and permeation rate of the above composite membrane depend on the thickness of the silicone resin layer. The silicone resin layer
This shows that by controlling the gas permeation rate, the separation performance of the composite membrane can also be controlled at the same time. As the thickness of the silicone resin layer increases, the separation performance of the composite membrane approaches the inherent separation performance of polysulfone, but this is not desirable because the permeation rate of hydrogen gas decreases.
As the thickness of the silicone resin layer decreases, the permeation rate of hydrogen gas increases, but the separation performance of the composite membrane decreases, so there is a range of preferable thicknesses of the silicone resin layer.

Table 3 Examples 9 to 11 In Example 1, the concentration of the N,N-dimethylacetamide solution of polysulfone to be coated on the polymer/inorganic compound porous membrane was set to 9. ] 2 and 15% by weight, all operations were performed in the same manner as in Example 1,
A composite membrane for gas separation was obtained.

Next, the permeation rates of hydrogen gas and nitrogen gas were measured using the above composite membrane, and the results are shown in Table 4.

As the concentration of the polysulfone coating solution increases, the separation coefficient does not change, but the permeation rate of hydrogen gas decreases. Furthermore, if the concentration of the polysulfone coating solution is less than 7% by weight, an effective thickness of the polysulfone layer cannot be obtained and the separation performance is significantly reduced. Therefore, it is necessary to select the coating solution depending on coating conditions such as the type of polymer, the type of solvent, the type of microporous polymeric membrane, and the temperature.

Table 4 Example 12 40% by weight of dioctyl phthalate (DOP), 20% by weight of finely powdered silicon oxide [Nibsil VN-3 (trade name), specific surface area 280 m2/liter, average particle size 16 mμ], and powdered polyvinylidene fluoride [ Kureha KF+1000
(Product Name)] 440 weight of the composition was mixed and kneaded in the same manner as in Example 1 to form pellets. The pellets were transferred to a 30 m/711φ twin screw extruder with an outer diameter of 14 and an inner diameter of 0.
．． Molding was performed using a hollow fiber manufacturing apparatus equipped with an 8 nrn hollow die. At this time, the extrusion amount was 4 kg/Hr, the take-up speed was 10 m/min, and the resin pressure was 20 kg/crrL.
It was 2. The formed hollow fibers were immersed in 1,1,1-trichloroethane (chlorocene (trade name)) for 10 minutes to extract DOP. The obtained porous hollow fibers containing vinylidene fluoride and inorganic substances had an outer diameter of 0.9 mm and an inner diameter of Q.
, 5 ram, the silicon oxide content of the inorganic fine particles was about 32%, and the porosity was 36%. Moreover, the average pore diameter was 0.03 μm.

On the outer surface of the porous membrane thus obtained, a 10% by weight nophopolytersulfone [IC1 100P (trade name)] nochloroform solution was dip-coated at 20°C, and then heated at 70"C for 20 minutes. Further, a 100 CpS toluene solution of methyltriacetoxysilane and hydroxyl-terminated dimethylsiloxane oligomer was added to the polyethersulfone thin layer at 20°C.
Dip coating under conditions of 20 μm to form a homogeneous layer of silicone resin. Next, the composite hollow fiber was
A three-dimensional crosslinking reaction was carried out under the conditions of 1100% RH at °C for 2 hours to obtain a composite membrane for gas separation. Using the obtained composite hollow fiber, a hollow fiber module was manufactured by using a conventionally known method and subjected to measurement.

When the permeation rate of hydrogen gas and nitrogen gas was measured using the above hollow fiber module, the permeation rate of hydrogen gas was 5.
2 X 10' cm3 (5TP)/crIl"se
c·mI (g, separation coefficient ("n, -N2)) was 57, indicating very excellent separation performance.

In addition, as a result of measuring the permeation rate of helium gas using this gas separation membrane, the permeation rate of helium gas was 4. I
X 10 "cIn"(s'rp)/cIrL"
5eC-Hg, and the separation coefficient (α, -N2) is 4
5, indicating very excellent separation performance.

Example] 3' 30% by weight of poly(dimethylsiloxane→-(methylvinylsiloxane) copolymer and benzoyl peroxide 05
A toluene solution containing 20% by weight was heated at 20°C.
Coated to a thickness of μm, then】20°C130
The crosslinking reaction was carried out by heat treatment for 30 minutes. A solution of 9M% polysulfone in N,N-dimethylacetamide was coated on the silicone membrane, and the solvent was removed by heating at 90°C for 15 minutes to obtain a composite membrane for hydrogen gas separation.

A hollow fiber module was manufactured using the above composite hollow fiber, and the permeation rates of hydrogen gas and nitrogen gas were measured. The permeation rate of hydrogen gas is 3.9 x 10”cm3 (S T
P )//cTL'' ・sec ・hoHg The separation coefficient (α□21°) was 38, indicating excellent separation performance.

Example 14 In Example 1, the inorganic fine particles contained in the polymer/inorganic compound porous membrane were finely powdered aluminum oxide (specific surface area 1oOm2/g, average particle diameter 20mμ), and the content of aluminum oxide was A composite membrane for gas separation was obtained in the same manner as in Example 1, except that a microporous polymer membrane having a porosity of 35% by weight and 49% was used.

The hydrogen gas permeation rate of the above composite membrane is 3.9X10-5 儂3
(S TP ) / crrt2- sec ・cmHg
So, the separation coefficient (αH2-N2) is 45, (αB2-02
) had an excellent separation performance of 7.

Example 15 In Example 1, the inorganic fine particles contained in the polymer/inorganic compound porous membrane were replaced with fine powdered titanium oxide (specific surface area: 50 m2).
Gas separation was carried out in the same manner as in Example 1, except that a porous membrane containing a polymeric inorganic compound with a titanium oxide content of 38% by weight and a porosity of 43% was used as the particle diameter of 30 mμ). A composite membrane was obtained.

The hydrogen gas permeation rate of the above composite membrane is 1.8X10-5cm
3(S TP )/c1n2-sec-crnHg,
The separation coefficient (αH2-N2) was 33, indicating excellent separation performance.

Example 16 In Example 12, the solution to be coated on the outer surface of the hollow fibers of the microporous membrane was a chloroform solution of 11 weight poly(2,6-dimethylphenylene-1,4-ether). A composite hollow fiber for hydrogen gas separation was obtained by using the same method as in Example 12 except for the following.

When the permeation rate of hydrogen gas and nitrogen gas was measured using the above composite hollow fiber, the permeation rate of hydrogen gas was 4. OX
] O' cm3 (STP) //Cm2・sec・c
mlit3, separation coefficient (αH2-N2) is 40
It had excellent separation performance.

Applicant Asahi Kasei Industries Co., Ltd. Agent Yutaka 1) Yoshio procedure
Amendment Written by: June 7, 1982 Kazuo Wakasugi, Commissioner of the Patent Office 1. Indication of the case Patent Application No. 1987-71526 2. Name of the invention Composite membrane for gas separation and its manufacturing method 3. Case of the person making the amendment Relationship with Patent applicant: 1-2-6 Dojimahama, Kita-ku, Osaka-shi, Osaka (C103) Asahi Kasei Industries, Ltd. President Teru Miyazaki 4, Agent: Sanshin, 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Building Room 204 Telephone 501-21385, "Claims" column and "Detailed Description of the Invention" column 6 of the specification to be amended, Contents of the amendment (1) Change the claims column of the specification. Correct as shown in the attached sheet.

(2) "If the amount of inorganic fine particles is less than 10% by weight, even if the plasticizer is large and uniformly dispersed in the polymer" on page 9 of the specification, lines 8 to 9, "inorganic fine particles are If the amount of plasticizer is less than 10% by weight, a porous membrane with large porosity consisting of micropores cannot be obtained, even if a large amount of plasticizer is uniformly dispersed in the polymer.''

Claims (1) Polymer/inorganic compound porous containing 10% by weight or more and less than 80% by weight of inorganic fine particles, having an average pore diameter of 0.1 gm or less and a porosity in the range of 30% to 80%. 11. Secondly, a thin layer (1) of a polymer having inherent separation performance with a separation coefficient of hydrogen and nitrogen mixed gas of 20 or more, and a polymer having a hydrogen permeability coefficient higher than that of the polymer forming the thin layer (1). is also laminated with a thin layer (]I) of a polymer that is at least 10 times larger, and the layer (
1) and the average layer thickness of the layer (JT)' [(H)
/(I)] is 5 to 7.

(2) Gas separation according to claim 1, wherein the inorganic fine particles contained in the polymer/inorganic compound porous membrane are one or a mixture of two or more of silicon oxide, titanium oxide, or aluminum oxide. Composite model 1.

(3) The polymer forming the polymer/inorganic composite porous membrane is
The composite membrane for gas separation according to claim 1, which is a polyolefin resin or a fluororesin.

(4) The composite membrane for gas separation according to claim 1, wherein the porous membrane containing a polymer and an inorganic substance is in the form of hollow fibers.

(5) The gas according to claim 1, wherein the average thickness of the thin polymer layer (I) having an inherent separation performance of hydrogen and nitrogen mixed gas is 20"-1 or less with a separation coefficient of 20"-1 or less. Composite membrane for separation.

(6) The composite membrane for gas separation according to claim 1 or 5, wherein the thin polymer layer (1) is made of a polysulfone resin or a polyphenylene ether resin.

(7) The composite membrane for gas separation according to claim 1, wherein the polymer thin layer (JT) is made of a silicone resin.

(8) Thin polymer layer (U) made of the silicone resin
is crosslinked and has an average thickness of 0.5 gm to 100 g
The composite membrane for gas separation according to claim 7, which is within the range of m.

(9) Gas separation according to any one of claims 1 to 8, which selectively separates at least hydrogen from a mixed gas consisting of hydrogen and one or more other gases. Composite membrane for use.

(10) Contains 10% by weight or more and less than 80% by weight of inorganic fine particles, has an average pore diameter of 0.1 μm or less, and has a porosity of 30%
Polymer solutions of the following (A) and (B) on a porous membrane containing polymers and inorganic substances in the range of 80% to 80%: (A) - Has inherent separation performance with a separation coefficient of 20 or more for hydrogen and nitrogen mixed gases Polymer solution (B): A solution of a polymer whose hydrogen permeability coefficient is at least 10 times larger than that of the polymer in the solution (A) is applied and dried to form a thin layer from each polymer solution. A method for producing a composite membrane for gas separation, characterized in that the composite membrane is obtained by

Claims (9)

[Claims] (1) Contains 10% by weight or more and less than 80% by weight of inorganic fine particles, has an average pore diameter of 01 μm or less, and has a porosity of 30%
A thin layer (1) of a polymer having an inherent separation coefficient of hydrogen and nitrogen mixed gas of 20 or more on a porous membrane containing a polymer and an inorganic material in the range of 80% to 80%; At least 10% less than the polymer forming the thin layer (1)
A thin layer of twice as large a polymer (ID) is laminated, and the ratio of average layer thicknesses of layer (1) and layer (II), respectively, is C(II)/(I).
) is 5 or more. (2) Gas separation according to claim 1, wherein the inorganic fine particles contained in the polymer/inorganic compound porous membrane are one or a mixture of two or more of silicon oxide, titanium oxide, or aluminum acid. Composite membrane for use. (3) The composite membrane for gas separation according to claim 1, wherein the polymer forming the polymer/inorganic composite porous membrane is a polyolefin resin or a fluororesin. (4) The composite membrane for gas separation according to claim 1, wherein the porous membrane containing a polymer and an inorganic substance is in the form of hollow fibers. (5) The average thickness of the thin layer (1) of a polymer having inherent separation performance with a separation coefficient of 20 or more for hydrogen and nitrogen gas mixtures is 1μ
2. The composite membrane for gas separation according to claim 1, wherein the membrane has a particle size of less than m. (6) The composite membrane for gas separation according to claim 5, in which the thin polymer layer (I) is made of polysulfone resin or polyphenylene ether resin. (7) The composite membrane for gas separation according to claim 1, wherein the thin polymer layer (l) is made of a silicone resin. (8) A thin layer of polymer made of the silicone resin (
II) is crosslinked and has an average thickness of 05 μm to 10
The composite membrane for gas separation according to claim 7, which has a diameter in the range of 0 μm. (9) The gas according to any one of claims 1 to 8, which selectively separates at least hydrogen from a gas mixture consisting of hydrogen and one or more other gases. Composite membrane for separation. 0 ■ The following (4 ), (B) polymer solution: (A): Solution of a polymer having inherent separation performance with a separation coefficient of hydrogen and nitrogen mixed gas of 20 or more (] 3): Solution with a hydrogen permeability coefficient of 20 or more (4) Manufacture of a composite membrane for gas separation, characterized in that a composite membrane is obtained by coating and drying a solution of a polymer at least 10 times larger than the polymer contained therein to form a thin layer from each polymer solution. Law.