JP2001038158A - 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, and consists of a porous support membrane and polystyrene.

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 includes a porous support membrane and polystyrene present on the inner surface of pores of the porous support membrane. Become.

[0008] In the above separation membrane, the average pore diameter of the porous support membrane is preferably in the range of 0.5 to 50 nm. Further, a non-porous layer may further be present on the surface to which the organic liquid mixture is supplied.

Materials for the porous support membrane include, for example,
A material selected from polyphenylene sulfone, polyphenylene sulfide sulfone, polyvinylidene fluoride, polyacrylonitrile, polyethylene, and polypropylene can be used. The shape of the separation membrane is selected from, for example, a hollow fiber membrane, a flat membrane, and a tubular membrane.

In the method for producing a separation membrane for an organic liquid mixture according to the present invention, the porous support membrane is brought into contact with a polystyrene solution, and then the solvent of the polystyrene solution is removed. A separation membrane for supplying an organic liquid mixture to one side of the membrane and separating a part of components in the organic liquid mixture in a gas phase from the other side, characterized in that the layer has the polystyrene layer formed thereon. It consists of a manufacturing method. Removal of the solvent of the polystyrene solution can be by contact with air or a liquid.

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:
The container is provided with a separation membrane as described above, an organic liquid mixture supply section on one side of the separation membrane, and a permeated organic liquid extraction section 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 the secondary side with an inert gas or liquid such as nitrogen. The method of sweeping the secondary side with an inert gas or a liquid having a temperature difference does not require maintaining a high vacuum,
It is more advantageous from the viewpoint of energy than the method of reducing the pressure.

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 C _n
H _{2n + 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 C _n H _2n . 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. And the general formula is C _n H _2n .

The aromatic hydrocarbon refers to a hydrocarbon containing at least one aromatic ring in one molecule, and specifically, for example, benzene, toluene having a side chain to benzene, xylene, or the like. Is a monocyclic compound.

The partial components separated from the organic liquid mixture through the membrane are 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.

[0020] The separation membrane of the present invention is characterized in that a porous membrane is used as a base membrane, and a polystyrene layer is formed on the pore inner diameter of the porous support membrane. 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

There are various methods for measuring the average pore size or the pore size distribution of the pore size of the membrane. The pore size of the separation membrane used in the present invention is estimated from the pore size of the porous support membrane and the concentration of the applied polystyrene solution. be able to. The thickness of the polystyrene layer can be estimated from the concentration of the polystyrene solution used and the porosity of the porous support membrane.

The average pore diameter of the porous support membrane can be defined as the following equation as the average pore diameter calculated from the water permeation rate and the porosity of the membrane. 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 water clay [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 diameter in the state where the polystyrene layer is provided on the inner surface of the fine pores of the porous support membrane is preferably in the range of 0.5 to 50 nm, and more preferably Is in the range of 0.5 to 20 nm, more preferably 1 to 10 nm. Therefore, the pore diameter of the porous support membrane is preferably in the range of 0.5 to 50 nm, and more preferably 0.1 to 50 nm. It is in the range of 5 to 20 nm, more preferably 1 to 10 nm. If the pore size of the porous support membrane is too small, the pore size will be blocked by the polystyrene layer and the permeation rate will decrease, and if it is too large, the selectivity of separation will deteriorate.

As the material of the porous support membrane, an organic polymer having durability against an organic liquid mixture and a polystyrene solution is preferably used. Examples of such a polymer material include polyphenylene sulfone, polyphenylene sulfide sulfone, polyvinylidene fluoride, polyacrylonitrile, polytetrafluoroethylene, polyethylene, and polypropylene.

The method of applying polystyrene to the inner surface of the micropores of the porous support membrane is not particularly limited as long as the porous structure of the porous support membrane is maintained, but the porous support membrane is placed in a polystyrene solution. Examples include a method of dipping and a method of applying a polystyrene solution to the porous support membrane. As a method for removing the solvent of polystyrene, a method of evaporating the solvent by applying heat, a method of evaporating the solvent by contacting with an inert gas, a method of replacing and removing the solvent of polystyrene by contacting with a solvent in which polystyrene is not dissolved And the like, and these methods may be used in combination.

It is important that the polystyrene layer of the present invention is provided on the inner surface of the fine pores of the porous support membrane. In order to exhibit more preferable separation performance, the separation membrane of the present invention is preferably further provided with a non-porous layer on the surface of the primary side that comes into contact with the organic liquid mixture. It is presumed that this can prevent the organic liquid mixture from entering the micropores of the membrane from the primary side and maintain a portion where capillary condensation occurs.

The material used for the 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 point that the permeation speed can be obtained advantageously,
In the situation where the separation operation is performed, a polymer in a rubber state is preferable, and examples of such a polymer material include polyisobutylene,
Polyisoprene, polybutadiene, poly-1-butene,
Poly-1-pentene, polyoxymethylene, poly-4-
Examples thereof include methylpentene-1, polyvinyl alcohol, 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]

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

Example 1 Average pore diameter 7.4 nm, outer diameter 1180 μm, inner diameter 762
The polyphenylene sulfone hollow fiber membrane of μm was cut into a length of about 30 cm, and ten pieces were immersed in a 2% by weight solution of polystyrene in dimethylacetamide overnight. After dipping, the solution was drained and air-dried, followed by vacuum drying to remove the dimethylacetamide solvent to obtain a hollow fiber composite membrane.

A bundle of eight hollow fiber composite membranes is inserted into a test glass tube mini-module having two branch pipes, and both ends of the glass tube mini-module are potted with an epoxy adhesive. A module was manufactured.

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 50 ° C and the linear velocity of the membrane surface inside the hollow fiber membrane.
It was fed at 0.2 m / sec. Nitrogen gas was flown outside the hollow fiber membrane at a membrane surface linear velocity of 2.0 m / sec, the nitrogen gas flowing outside was captured by a liquid nitrogen cold trap, and permeated vapor was condensed and recovered. The concentration of the permeate component was measured by gas chromatography, and the separation coefficient (α) was calculated.

The separation coefficient is obtained by dividing "the concentration of benzene in the permeate / the concentration of n-heptane in the permeate" by "the concentration of benzene in the supply liquid / the concentration of n-heptane of the supply liquid".

As a result, the separation coefficient was 2.28. The membrane permeation rate was 0.024 kg / (m ² · hr).

Example 2 A composite hollow fiber membrane was prepared in the same manner as in Example 1 to produce a test membrane module. The inner surface of the obtained hollow fiber membrane was coated with a crosslinked silicone solution. In the coating method, a silicone tube was connected to the test 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 from the crosslinked silicone solution, gently purged with nitrogen gas for about 2 minutes, and then heated in a 60 ° 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 was prepared by using BY16-872 manufactured by Toray Silicone Co., Ltd. (molecular weight: about 120,000, side chain introduction ratio: about 1.6% in siloxane unit) to prepare a 2% by weight cyclohexane solution. As the tolylene diisocyanate solution, a 0.9% by weight cyclohexane solution was prepared using tolylene diisocyanate coronate T-80 manufactured by Nippon Polyurethane Co., Ltd.

Using the obtained test membrane module, an experiment for separating an organic liquid mixture was performed in the same manner as in Example 1. The separation factor was 2.32. The membrane permeation rate is 0.0
It was 15 kg / (m ² · hr).

Comparative Example 1 Average pore diameter 7.4 nm, outer diameter 1180 μm, inner diameter 762
A μm polyphenylene sulfone hollow fiber membrane was cut into a length of about 20 cm, eight were bundled and inserted into a glass tube mini-module, and both ends were potted with an epoxy adhesive to produce a test membrane module. Using this test 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 organic liquid mixture was supplied at a flow rate of 0.2 m / sec to the inside of the hollow fiber membrane at a temperature of about 50 ° C. Nitrogen gas was flown outside the hollow fiber membrane at a membrane surface linear velocity of 2.0 m / sec, the nitrogen gas flowing outside was trapped by a liquid nitrogen cold trap, and permeated vapor was condensed and recovered. The concentration of the permeate component was measured by gas chromatography, and the separation coefficient was calculated. The separation coefficient of the test membrane module was 1.07. The membrane permeation rate was 8.95 kg / (m ² · hr).

Comparative Example 2 The inner surface of the hollow fiber membrane of the test membrane module prepared in the same manner as in Comparative Example 1 was coated with a crosslinked silicone solution. In the coating method, a silicone tube was connected to the test 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 from the crosslinked silicone solution, gently purged with nitrogen gas for about 2 minutes, and then heated in a 60 ° 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 was prepared by using BY16-872 manufactured by Toray Silicone Co., Ltd. (molecular weight: about 120,000, side chain introduction ratio: about 1.6% in siloxane unit) to prepare a 2% by weight cyclohexane solution. The tolylene diisocyanate solution was 0.9 wt% using tolylene diisocyanate coronate T-80 manufactured by Nippon Polyurethane Co., Ltd.
Was prepared in cyclohexane.

Using the test membrane module obtained, an experiment for separating an organic liquid mixture was performed in the same manner as in Comparative Example 1. The separation factor was 1.81. The membrane permeation rate is 2.4
It was 1 kg / (m ² · hr).

[0040]

According to the separation membrane and the separation method of the present invention, since polystyrene is provided on the inner surface of the fine pores of the membrane, a part of the substance can be extracted from the organic liquid mixture with a higher separation coefficient. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 69/06 B01D 69/06 69/08 69/08 69/10 69/10 71/26 71/26 71 / 34 71/34 71/42 71/42 71/68 71/68 (72) Inventor, Yoshinari Fusaoka 1-1-1, Sonoyama, Otsu-shi, Shiga Prefecture Toray Co., Ltd. Shiga Plant F-term (reference) 4D006 GA25 MA01 MA02 MA03 MA06 MA22 MB01 MC22 MC23 MC24X MC29 MC39 MC62X NA01 NA45 NA46 NA64 PA02 PB13 PC80 4D011 AA17

Claims (11)

[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 separation membrane for an organic liquid mixture, comprising a porous support membrane and polystyrene present on the inner surface of pores of the porous support membrane. 2. The porous support membrane has an average pore size of 0.5 to 5
The separation membrane for an organic liquid mixture according to claim 1, wherein the thickness is in a range of 0 nm. 3. The separation membrane for an organic liquid mixture according to claim 1, wherein a non-porous layer is further provided on a surface side to which the organic liquid mixture is supplied. 4. The material according to claim 1, wherein the material of the porous support membrane is selected from polyphenylene sulfone, polyphenylene sulfide sulfone, polyvinylidene fluoride, polyacrylonitrile, polyethylene and polypropylene. A separation membrane for an organic liquid mixture according to the above. 5. The separation membrane is selected from a hollow fiber membrane, a flat membrane and a tubular membrane.
The separation membrane for an organic liquid mixture according to any one of the above. 6. The method according to claim 6, wherein after contacting the porous support membrane with a polystyrene solution, the solvent of the polystyrene solution is removed, and the polystyrene layer is formed on the inner surface layer of the pores of the porous support membrane. A method for producing a separation membrane for an organic liquid mixture. 7. The method for producing a separation membrane for an organic liquid mixture according to claim 6, wherein the removal of the polystyrene solution is performed by contact with air or a liquid. 8. An organic liquid mixture is supplied to one side of the separation membrane according to claim 1, and a part of the organic liquid mixture is separated in a gas phase from the other side. A method for separating an organic liquid mixture. 9. The organic liquid mixture containing an aromatic hydrocarbon, and some components to be separated are an organic liquid mixture having a higher aromatic hydrocarbon component concentration than the organic liquid mixture. 9. The method for separating an organic liquid mixture according to item 8. 10. The method for separating an organic liquid mixture according to claim 9, wherein the organic liquid mixture is gasoline containing an aromatic hydrocarbon. 11. A separation membrane according to any one of claims 1 to 5, which is disposed in a vessel, an organic liquid mixture supply section on one side of the separation membrane, and a permeated organic liquid at a position opposite to the membrane. An organic liquid mixture separation device having an outlet.