JP2001038155A - Separation membrane for organic liquid mixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrially applicable, more efficient membrane separation technique for an organic liquid mixture. SOLUTION: This separation membrane is used for a membrane separation process that comprises feeding an organic liquid mixture to one side of separation membrane and separating and recovering a part of components of the organic liquid mixture in a gas phase from the other side, wherein: the membrane is a composite membrane formed by laminating a non-porous layer on the surface of a porous support membrane; the difference in height between the highest point and the lowest point in the surface of the nonporous layer is adjusted to <=1 μm; and also the average deviation in height of all the point on the surface of the nonporous layer is adjusted to <=0.1 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic liquid mixture separation membrane, an organic liquid mixture separation apparatus, and a separation method using the organic liquid mixture separation membrane used for changing the composition of the organic liquid mixture.

[0002]

2. Description of the Related Art Membrane separation technology has been used in various fields including the food industry, the medical field, seawater desalination, ultrapure water, and other water treatment fields. And has been industrialized. Membrane separation technology has attracted attention as a resource-saving, energy-saving and low-environmental load technology.The application of this membrane separation technology to non-aqueous fields, for example, petroleum refining processes and petrochemical industries, has recently been studied for the first time. I have. Separation in the petroleum refining process and petrochemical industry is carried out by combining existing separation technologies, mainly distillation methods. Developing and applying more advantageous separation technologies from the standpoint of resource and energy conservation and the environment Is required. Against this background, there is a need to develop and commercialize membrane separation technology as a technology in the petroleum refining process and petrochemical industry.

[0003] JP-A-63-173182 and JP-A-63-175607 disclose a method for concentrating volatile substances such as alcohol. However, there is a problem that a membrane in which a polymer having a high alcohol affinity is coated on the surface of the porous membrane and the permeation speed is reduced when the pores of the membrane are wetted. JP-A-2-2852, JP-A-2-2-2
No. 854 discloses a polyurea / urethane membrane for separating an aromatic component and a non-aromatic component. However, there is a problem that the mechanical strength is low because an active layer is formed by depositing a thin film of a low molecular weight copolymer. JP-A-2-138136 discloses a method for separating an aromatic hydrocarbon from a mixture of an aromatic hydrocarbon and a saturated hydrocarbon using a hydrophilic membrane impregnated with polyethylene glycol. However, it cannot be said that the separation coefficient is high and the transmission speed is high.

[0004]

The above-mentioned prior art has sufficient durability against organic liquids, satisfies separation performance and membrane permeation speed, and is more economically advantageous than existing separation equipment. It can not be said. Further, in the case of a petroleum refining process, the separation of gaseous state is disadvantageous in terms of energy due to the large amount of treatment. For these reasons, at present, there is no example of membrane technology being applied to the petroleum refining process or the petrochemical industry.

If the composition of the organic liquid mixture can be changed, in the case of a petroleum refining process, the octane number of gasoline or the cetane number of light oil can be improved. Further, even if the target component cannot be completely separated by the membrane, it is economically advantageous only by changing the raw material composition before entering the distillation facility, and if the distillation process can be replaced with a membrane process. It goes without saying that it is economically advantageous. Further, it is advantageous from the viewpoint of low environmental load if harmful substances such as benzene can be removed from gasoline. Furthermore, if olefins can be separated and concentrated, an economically advantageous raw material production method for polymers and petrochemical products can be provided.

It is an object of the present invention to provide a separation membrane for extracting a part of an organic liquid mixture, which has high separation performance and high permeation performance, and a separation method.

[0007]

In order to solve the above-mentioned problems, a separation membrane for an organic liquid mixture according to the present invention supplies an organic liquid mixture to one side of a membrane and vapor-phases the organic liquid mixture from the other side. A separation membrane used in a method of separating some components therein, wherein the separation membrane is a composite membrane in which a non-porous layer is laminated on a porous support membrane, and the lowest point on the surface of the non-porous layer is The height between the highest points is 1 μm or less, and the average deviation of all points where the non-porous layer surface is flat-fitted is 0.2 μm.
m or less.

In the above separation membrane, the height between the lowest point and the highest point on the surface of the porous support membrane is 2 μm or less, and the average deviation of all points where the surface of the porous support membrane is flat-fitted is zero. .2 μm or less. Further, it is preferable that the average pore diameter of the porous support membrane is in the range of 0.5 to 50 nm.

[0009] The shape of the separation membrane is selected from, for example, a hollow fiber membrane, a flat membrane and a tubular membrane.

In the separation membrane according to the present invention, the non-porous layer is preferably made of a rubber-like polymer. As the rubbery polymer, a crosslinked silicone or the like can be used.

In the method for separating an organic liquid mixture according to the present invention, the organic liquid mixture is supplied to one side of the separation membrane as described above, and a part of the components in the organic liquid mixture is vapor-phased from the other side. The method comprises the steps of separating. The organic liquid mixture contains, for example, an aromatic hydrocarbon, and some components to be separated are organic substances having a higher aromatic hydrocarbon component concentration than the organic liquid mixture. The organic liquid mixture is, for example, gasoline containing an aromatic hydrocarbon.

The organic liquid mixture separation device according to the present invention comprises:
A separation membrane as described above is disposed in a container, and an organic liquid mixture supply section is provided on one side of the separation membrane, and a permeated organic liquid take-out section is provided at a position opposite to the membrane.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. The separation method using a membrane to which the present invention is directed is to supply an organic liquid mixture to a primary side of the membrane and to separate some components in the mixture from a secondary side opposite to the primary side. In that case, it is usually preferable to reduce the pressure on the secondary side or to sweep with an inert gas such as nitrogen or a liquid. The method of sweeping the secondary side with an inert gas or a liquid having a temperature difference is advantageous in terms of energy from the method of reducing the pressure, because it is not necessary to maintain a high vacuum.

The organic liquid mixture in the present invention is not particularly limited as long as it is a mixture of combinations of organic compounds having different chemical bonds or molecular structures. For example, naphtha, gasoline, kerosene, petroleum fractions containing components such as light oil can be used, and examples thereof include paraffinic hydrocarbons, olefinic hydrocarbons, naphthenic hydrocarbons, and aromatic hydrocarbons. Among them, those containing two or more hydrocarbon components. Also,
It may contain a non-hydrocarbon component such as a sulfur compound, a nitrogen compound, an oxygen compound, and a metal compound, and may contain a gas component such as natural gas, carbon dioxide gas, and helium gas.

Here, the paraffinic hydrocarbon is Cn
H2n + 2 is a saturated chain compound having a molecular formula of unbranched n-paraffin and branched isoparaffin, specifically, for example, n-pentane, n-hexane, n-heptane,
Examples include n-octane, n-nonane, n-decane, n-undecane, n-dodecane, 2-methylbutane, 2,2-dimethylpropane and the like.

The olefinic hydrocarbon is usually a hydrocarbon having a double bond, and more specifically, a single double bond is a chain hydrocarbon represented by the general formula of CnH2n. Specifically, for example, 1-pentene, 1-hexene, 1
-Heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene and the like.

Naphthenic hydrocarbons are hydrocarbons containing at least one saturated ring in one molecule and are cyclic compounds in which cyclopentane having 5 carbon atoms and cyclohexane having 6 carbon atoms are the most basic. The general formula is CnH2n.
The aromatic hydrocarbon refers to a hydrocarbon containing at least one aromatic ring in one molecule, and specifically, for example,
It is a monocyclic compound such as benzene or toluene or xylene with a side chain attached to benzene.

The part of the components separated from the organic liquid mixture through the membrane is not particularly limited, but the above-mentioned olefinic hydrocarbons, particularly aromatic hydrocarbons, can be preferably defined. Further, the separation membrane of the present invention is preferably used in an operation of extracting an organic liquid mixture having a higher aromatic hydrocarbon component concentration from an organic liquid mixture containing an aromatic hydrocarbon. Is gasoline.

The separation membrane of the present invention comprises a porous membrane as a substrate membrane and a non-porous layer laminated on the porous support membrane. The separation point between the lowest point and the highest point on the surface of the non-porous layer is provided. Height 1
μm or less, and the average deviation of all points where the surface of the non-porous layer is flat-fitted is 0.1 μm or less. In the separation of the organic liquid mixture using the separation membrane of the present invention, at least one component of the organic liquid mixture permeates the separation membrane in a vapor state or a state in which capillary condensation occurs in the fine pores of the porous membrane. It is estimated that Furthermore, in order to achieve high separation performance, it is important to provide a non-porous layer on the surface that comes into contact with the organic liquid mixture on the primary side. It is speculated that the intrusion of the organic liquid mixture can be prevented and the portion where capillary condensation occurs can be maintained.

There are various methods for measuring the height difference by observing the unevenness on the surface of the separation membrane, and the height difference on the surface of the separation membrane used in the present invention can be measured using a white interference microscope. The white interference microscope is manufactured by zygo “z”
ygoNewView100withzoom "can be used. The observation magnification is preferably 200 to 800 times.

Conventionally, a composite membrane having a non-porous layer laminated on a porous support membrane, wherein the thickness of the non-porous layer is 3 μm or less, and the height between the lowest point and the highest point on the surface of the non-porous layer Is 1
μm, the average deviation of all points where the surface of the non-porous layer was flat-fitted is greater than 0.1 μm,
There were many disadvantages, and the organic liquid mixture penetrated into the micropores of the membrane, and high separation performance was not exhibited. The height between the lowest point and the highest point on the surface of the non-porous layer found in the present invention is 1 μm or less, and the average deviation of all points that are flat-fitted on the surface of the non-porous layer is 0.1 μm or less. It has been found that certain separation membranes have few defects and exhibit high separation performance by preventing the organic liquid mixture from entering the micropores of the membrane.

In order for the separation membrane of the present invention to exhibit high separation performance, it is important that the non-porous layer has no defect.
In order to make it difficult to form defects, a nonporous layer with few defects can be formed by using a porous support membrane having a smooth surface and laminating a nonporous layer on the smooth surface. In order to form such a non-porous layer with few defects, it is necessary to use a porous support having a smooth surface,
The height between the lowest point and the highest point on the surface of the porous support is 2 μm or less, and the average deviation of all points where the surface of the porous support membrane is flat-fitted is 0.2 μm or less. preferable.

There are various methods for measuring the average pore diameter or the pore diameter distribution of the pore diameter of the membrane. The average pore diameter of the porous support membrane used in the present invention is determined from the water permeation rate and the porosity of the membrane. The calculated average pore diameter can be defined as in the following equation. D _P = 2 · (L _P · λ · 8η / Φ _W ) ^1/2 where D _P is the average pore size [cm] and L _P is the water permeability [cm ³ ·
dyn ^-1 · s ^-1 ], λ is the film thickness [cm], η is the viscosity of water [dyn · s · cm ² ], and Φ _W is the water content, that is, the porosity of the film.

In order for the separation membrane to exhibit high performance, the average pore size of the porous support membrane is preferably in the range of 0.5 to 50 nm, preferably 0.5 to 20 nm, more preferably 1 to 20 nm. The range is from 10 to 10 nm. If the pore size of the porous support membrane is too small, the permeation rate decreases, and if it is too large, the selectivity of separation deteriorates.

As the material of the porous support membrane, an organic polymer which is durable against the organic liquid mixture and the solvent for laminating the non-porous layer is preferably used. Examples of such a polymer material include polyphenylene sulfone, polyphenylene sulfide sulfone, polytetrafluoroethylene, polyacrylonitrile, polyethylene, and polypropylene.

The method for laminating the non-porous layer on the porous support membrane is not particularly limited as long as the porous structure of the porous support membrane is maintained. A method of applying a solution of a polymer to be formed is exemplified. As a method for removing the solvent of the polymer forming the porous layer, a method of evaporating the solvent by applying heat, a method of evaporating the solvent by contacting with an inert gas, a solvent in which the polymer forming the porous layer is not dissolved And a method of removing the solvent by contacting with a solvent. These methods may be used in combination.

The material used for the non-porous layer provided on the surface in contact with the organic liquid mixture preferably has a property of permeating at least one component vapor and preventing the permeation of the organic liquid mixture as a liquid. From the viewpoint that the permeation rate can be advantageously obtained, a polymer in a rubber state is preferable in the case of performing the separation operation. Examples of such a polymer material include polyisobutylene, polyisoprene, polybutadiene, and poly-1-.
Butene, poly-1-pentene, polyoxymethylene, poly-4-methylpentene-1, polyvinyl alcohol,
Examples thereof include polydimethylsiloxane, polyvinylidene chloride, and polyvinyl fluoride. Polydimethylsiloxane having a crosslinked structure, that is, crosslinked silicone, is particularly preferably used in that it has excellent durability against an organic liquid mixture and excellent thin film forming properties.

The form of the separation membrane may be any of a flat membrane, a tubular membrane, a hollow fiber membrane and the like. Furthermore, according to the present invention, the separation membrane of the present invention, an organic liquid mixture separation device having an organic liquid mixture supply part on one side of the separation membrane and a permeate organic liquid take-out part on the opposite side of the separation membrane, that is, a separation membrane Modules can be created. As the form of the separation membrane module, any form such as a flat type using a flat membrane, a spiral type, a pleated type, a tubular type, and a hollow fiber type can be used in the present invention. Considering the time of modularization,
As the shape of the separation membrane, a hollow fiber membrane is preferably used from the viewpoints of self-supporting property and mechanical / mechanical properties of the membrane, few components of the module, and solvent resistance.

[0029]

The present invention will be described below with reference to specific examples and comparative examples, but the present invention is not limited to these examples.

Example 1 The height between the lowest point and the highest point on the inner surface of the hollow fiber membrane was 0.5
09 μm, the average deviation of all points where the inner surface of the hollow fiber membrane was flat-fitted was 0.084 μm, the average pore diameter was 7.5 nm,
A polyphenylene sulfone hollow fiber membrane having an outer diameter of 1180 μm and an inner diameter of 780 μm is cut into a length of about 30 cm, and ten hollow fiber membranes are bundled and inserted into a glass tube mini-module having two branch pipes. Were potted with an epoxy adhesive to produce a non-porous laminating membrane module. The inner surface of the hollow fiber membrane of the obtained non-porous lamination membrane module was coated with a crosslinked silicone solution. The coating method is to connect a silicone tube to the non-porous laminating membrane module and apply a cross-linked silicone solution.
The inside of the hollow fiber membrane was coated by pouring into the inside of a 6 cc tube. The test membrane module was drained from the crosslinked silicone solution and gently purged with nitrogen gas for about 2 minutes.
Heated in 0 ° C. oven for 5 minutes. The method for preparing the crosslinked silicone solution was obtained by mixing equal amounts of a cyclohexane solution of the comb-shaped amino-modified silicone and a cyclohexane solution of tolylenediisocyanate as a crosslinking agent. The comb-shaped amino-modified silicone solution is manufactured by Toray Silicone Co., Ltd., BY16-872 (molecular weight: about 120,000, side chain introduction rate: about 1.6% in siloxane unit)
Was used to prepare a 2% by weight cyclohexane solution. As a tolylene diisocyanate solution, a 0.9% by weight cyclohexane solution was prepared using tolylene diisocyanate coronate T-80 manufactured by Nippon Polyurethane. When the non-porous laminating membrane module was disassembled and the inner surface of the silicone-coated hollow fiber membrane was observed, the height between the lowest point and the highest point on the surface was 0.213 μm, and the surface of the supporting membrane was flat. The average deviation of all fitted points was 0.047 μm. Using the obtained silicone-coated hollow fiber membrane, bundle and insert eight hollow fiber composite membranes into a glass tube mini-module with two branch tubes, and attach both ends of the glass tube mini-module with an epoxy adhesive. Potting was performed to produce a test membrane module.

Using this glass tube mini-module for test, a separation experiment of an organic liquid mixture in which benzene having a benzene concentration of 9 mol% was mixed with n-heptane was performed. The temperature of the organic liquid mixture is about 70 ° C and the linear velocity of the membrane surface inside the hollow fiber membrane
It was supplied at 0.1 m / sec. Nitrogen gas was flown outside the hollow fiber membrane at a linear velocity of 1.0 m / sec on the membrane surface, the nitrogen gas flowing outside was trapped by a liquid nitrogen cold trap, and the permeated vapor was condensed and recovered. Was measured by gas chromatography, and the separation coefficient (α) was calculated.

The separation coefficient is obtained by dividing "the benzene concentration of the permeated liquid / the n-heptane concentration of the permeated liquid" by "the benzene concentration of the supplied liquid / the n-heptane concentration of the supplied liquid".

As a result, the separation coefficient was 2.2. The membrane permeation rate was 1.38 kg / (m ² · hr).

Example 2 The height of the hollow fiber membrane used as the porous support membrane between the lowest point and the highest point on the inner surface of the hollow fiber membrane was 0.622 μm, and the inner surface of the hollow fiber membrane was flat-fitted. A silicone-coated hollow fiber membrane was prepared in the same manner as in Example 1 except that the average deviation of the points was 0.091 μm, and the inner surface of the silicone-coated hollow fiber membrane was observed.
The height between the lowest point and the highest point on the surface is 0.197 μm
The average deviation of all points where the surface of the support film was fitted in a plane was 0.043 μm. Using the obtained silicone-coated hollow fiber membrane, a test membrane module was produced in the same manner as in Example 1. Using the module, an experiment of separating an organic liquid mixture was performed in the same manner as in Example 1.
The separation factor was 2.15. The membrane permeation rate is 1.42 kg
/ (m ² · hr).

Comparative Example 1 The height between the lowest point and the highest point on the inner surface of the hollow fiber membrane was 4.7.
At 17 μm, the average deviation of all points where the inner surface of the hollow fiber membrane was flat-fitted was 0.677 μm, and the average pore diameter was 27.2 n.
m, outer diameter 997 μm, inner diameter 685 μm poly-2,6-
The dimethyl-1,4-phenylene oxide hollow fiber membrane is cut into a length of about 30 cm, and ten hollow fiber membranes are bundled and inserted into a glass tube mini-module having two branch pipes. Both ends were potted with an epoxy adhesive to produce a non-porous lamination membrane module. The inner surface of the hollow fiber membrane of the obtained non-porous lamination membrane module was coated with a crosslinked silicone solution. In the coating method, a silicone tube was connected to the nonporous laminating membrane module, and a crosslinked silicone solution was poured into the inside of the 6 cc tube to coat the inside of the hollow fiber membrane. The test membrane module was drained of the cross-linked silicone solution, gently purged with nitrogen gas for about 2 minutes, and then
Heated for a minute. The method for preparing the crosslinked silicone solution was obtained by mixing equal amounts of a cyclohexane solution of the comb-shaped amino-modified silicone and a cyclohexane solution of tolylenediisocyanate as a crosslinking agent. As the comb-shaped amino-modified silicone solution, a 2% by weight cyclohexane solution was prepared by using BY16-872 (Toray Silicone Co., Ltd., molecular weight: about 120,000, side chain introduction ratio: about 1.6% in siloxane unit). As a tolylene diisocyanate solution, a 0.9% by weight cyclohexane solution was prepared using tolylene diisocyanate coronate T-80 manufactured by Nippon Polyurethane. When this non-porous laminating membrane module was disassembled and the inner surface of the silicone-coated hollow fiber membrane was observed, the height between the lowest point and the highest point on the surface was 4.124 μm.
m, the average deviation of all points at which the surface of the support film was flat-fitted was 0.633 μm. Using the obtained silicone-coated hollow fiber membrane, bundle and insert eight hollow fiber composite membranes into a glass tube mini-module with two branch tubes, and attach both ends of the glass tube mini-module with an epoxy adhesive. Potting was performed to produce a test membrane module.

Using this test glass tube mini-module, a separation experiment of an organic liquid mixture in which benzene having a benzene concentration of 9 mol% was mixed with n-heptane was performed. The temperature of the organic liquid mixture is about 70 ° C and the linear velocity of the membrane surface inside the hollow fiber membrane
It was supplied at 0.1 m / sec. Nitrogen gas was flown outside the hollow fiber membrane at a linear velocity of 1.0 m / sec on the membrane surface, the nitrogen gas flowing outside was trapped by a liquid nitrogen cold trap, and the permeated vapor was condensed and recovered. Was measured by gas chromatography, and the separation coefficient (α) was calculated.

The separation coefficient is obtained by dividing "the benzene concentration of the permeated liquid / the n-heptane concentration of the permeated liquid" by "the benzene concentration of the supplied liquid / the n-heptane concentration of the supplied liquid".

As a result, the separation coefficient was 1.1. The membrane permeation rate was 8.3 kg / (m ² · hr).

[0039]

According to the separation membrane and the separation method of the present invention, it is possible to take out some substances from the organic liquid mixture with a higher separation coefficient.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B01D 71/24 B01D 71/24 71/70 71/70 C10G 31/00 C10G 31/00 (72) Inventor Yoshinari Fusaoka 1-1-1 Sonoyama, Otsu City, Shiga Prefecture F-term in the Shiga Plant of Toray Industries (reference) 4D006 GA25 HA01 HA21 HA41 HA61 HA71 JB01 KE30R MA01 MA02 MA03 MA09 MA22 MA30 MA31 MA40 MC21 MC22 MC23 MC28 MC30 MC39 MC62 MC65X NA46 PA05 PB13 PB70 PC80

Claims (9)

[Claims] 1. A separation membrane used in a method for supplying an organic liquid mixture to one side of a membrane and separating a part of components in the organic liquid mixture in a gas phase from the other side, wherein the separation membrane is porous. A composite membrane in which a non-porous layer is laminated on a porous support membrane, the height between the lowest point and the highest point on the surface of the non-porous layer is 1 μm or less, and the surface of the non-porous layer is flat-fitted. Wherein the average deviation of the points is 0.1 μm or less. 2. The height between the lowest point and the highest point on the surface of the porous support membrane is 2 μm or less, and the average deviation of all points where the surface of the porous support membrane is flat-fitted is 0.2 μm or less. The separation membrane for an organic liquid mixture according to claim 1, wherein the separation membrane is provided. 3. The porous support membrane having an average pore diameter of 0.5 to 5
The organic liquid mixture separation membrane according to claim 1, wherein the separation membrane is in a range of 0 nm. 4. The separation membrane for an organic liquid mixture according to claim 1, wherein the porous support membrane is selected from a hollow fiber membrane, a flat membrane, and a tubular membrane. 5. The separation membrane for an organic liquid mixture according to claim 1, wherein the non-porous layer is made of a rubber-like polymer. 6. The separation membrane for an organic liquid mixture according to claim 1, wherein the material of the non-porous layer is made of silicone. 7. An organic liquid mixture having a higher aromatic hydrocarbon component concentration is taken out of the organic liquid mixture containing an aromatic hydrocarbon through the separation membrane according to any one of claims 1 to 6. , Organic liquid mixture separation method. 8. The method for separating an organic liquid mixture according to claim 7, wherein the organic liquid mixture is gasoline containing an aromatic hydrocarbon. 9. A separation membrane according to any one of claims 1 to 6, which is disposed in a container, and has an organic liquid mixture supply section on one side of the separation membrane and a permeate organic liquid take-out section on the other side. An organic liquid mixture separation device characterized by the above-mentioned.