JP2001038156A - 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 an ionic group-containing polymer having a silver ion as a counter ion.

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 for a method of separating some components in the separation membrane, wherein the separation membrane contains a porous support membrane and an ionic group containing silver ions present on the inner surface of pores of the porous support membrane as counter ions. And a polymer.

[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.

[0010] In the separation membrane according to the present invention, the ionic group-containing polymer preferably has a sulfonic acid group or a carboxylic acid group.

The method for producing a separation membrane for an organic liquid mixture according to the present invention comprises the steps of: (A) contacting a porous support membrane with a solution of an ionic group-containing polymer and then removing a solvent of the ionic group-containing polymer solution; And further contacted with an aqueous solution of silver ions to form an ionic group-containing polymer having silver ions as counter ions on the inner surface layer of the pores of the porous support membrane, comprising the steps of: A method for producing a separation membrane for supplying one side and separating a part of components in an organic liquid mixture in a gaseous phase from the other side, or (B) an ion in which a porous support membrane has silver ions as counter ions. After contact with the solution of the ionic group-containing polymer, the solvent of the solution of the ionic group-containing polymer with silver ions as a counter ion is removed, and silver ions are formed as counter ions on the inner surface layer of the pores of the porous support membrane. Ionic group-containing polymer Made, characterized in that was, the organic liquid mixture is fed to one side of the film, a method for manufacturing a separation membrane for separating a portion of components of the organic liquid mixture in the gas phase from the other side.

Further, 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.

[0015]

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 such as nitrogen or a liquid. 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 is a hydrocarbon containing at least one aromatic ring in one molecule, and specifically, for example, benzene, toluene having a side chain attached to benzene, xylene, etc. 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.

The separation membrane of the present invention is characterized in that a porous membrane is used as a base membrane, and a layer of an ionic group-containing polymer having silver ions as a counter ion is formed in the pore inner diameter of the porous support membrane. I do. 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 determined by the pore size of the porous support membrane and the applied ionic group-containing polymer solution. It can be estimated from the concentration.
The thickness of the ionic group-containing polymer layer can be estimated from the concentration of the used ionic group-containing polymer solution 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 a state in which the ionic group-containing polymer layer having silver ions as a counter ion is provided on the inner surface of the fine pores of the porous support membrane is 0.5 to 0.5%. It is preferably in the range of 50 nm, preferably 0.5 to 20 nm, more preferably 1 to 10 n.
m, the pore size of the porous support membrane is preferably in the range of 0.5 to 50 nm,
Preferably, it is 0.5-20 nm, more preferably 1-1.
The range is 0 nm. If the pore size of the porous support membrane is too small, the pore size is blocked by an ionic group-containing polymer layer having silver ions as a counter ion, and the permeation rate decreases. If the pore size is too large, the selectivity of separation deteriorates.

As the material of the porous support membrane, an organic polymer which is durable with respect to the organic liquid mixture and the ionic group-containing polymer solution is preferably used. Examples of such polymer materials include polyphenylene sulfone, polyphenylene sulfide sulfone, polytetrafluoroethylene,
Examples thereof include polyvinylidene fluoride, polyacrylonitrile, polyethylene, and polypropylene.

A method for applying an ionic group-containing polymer using silver ions as a counter ion on the inner surface of the pores of the porous support membrane is as follows.
There is no particular limitation as long as the porous structure of the porous support membrane is maintained, and a method of immersing the porous support membrane in a solution of an ionic group-containing polymer with silver ions as counter ions, Is applied to a porous support membrane with an ionic group-containing polymer having the following as a counter ion. As a method of removing the solvent of the ionic group-containing polymer with silver ions as a counter ion, a method of evaporating the solvent by applying heat, a method of evaporating the solvent by contacting an inert gas, and a method of removing the ionic group-containing polymer are used. A method in which the solvent of the ionic group-containing polymer is displaced and removed by contact with a solvent that does not dissolve may be mentioned, and these methods may be used in combination.

It is important that the layer of the ionic group-containing polymer of the present invention having silver ions as a counter ion is provided on the inner surface of the fine pores of the porous support membrane. Although ionic group-containing polymers are widely used as ion exchange resins, ionic groups having silver ions as counter ions are anionic ionic groups, and ionic groups having sulfonic acid groups or carboxylic acid groups. Containing polymers are preferred. Further, as a material of the ionic group-containing polymer, perfluorosulfonic acid,
There are polystyrene sulfonic acid, polyvinyl sulfonic acid, polystyrene carboxylic acid, polyacrylic acid, and the like. In particular, "Nafion" manufactured by DuPont, which is a typical polymer of perfluorosulfonic acid, is preferably used. Silver nitrate, tetrafluorosilver nitrate, or the like is preferably used as a silver salt used as a raw material for silver ions. Further, as the ionic group-containing polymer to be used, a plurality of polymers may be used, and a plurality of silver salts may be used.

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 which is in contact with the organic liquid mixture on the primary side. 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.

[0032]

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 As a polymer containing an ionic group, a commercially available "Nafion solution" manufactured by DuPont was diluted with ethanol, and a 5% by weight solution was prepared to obtain a composite membrane forming solution. Average pore size 7.5
A polyphenylene sulfone hollow fiber membrane having a diameter of nm, an outer diameter of 1180 μm, and an inner diameter of 780 μm was cut into a length of about 30 cm, and ten of them were immersed in a composite membrane forming solution for 12 hours. Then, it was immersed in a 1N-NaOH aqueous solution for 12 hours, and immersed in a 2N-silver tetrafluoroborate aqueous solution for 24 hours. After immersion, the solution was drained and air-dried, followed by vacuum drying to remove the 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. 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 of 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 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 conducted. 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 flowed outside the hollow fiber membrane at a linear velocity of 2.0 m / sec on the membrane surface, the nitrogen gas flowing outside was trapped by a liquid nitrogen cold trap, and permeated vapor was condensed and recovered. The concentration was measured by gas chromatography, and the separation coefficient (α) was calculated.

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

As a result, the separation coefficient was 2.63. The membrane permeation rate was 0.0161 kg / (m ² · hr).

Example 2 The solution concentration of the used ionic group-containing polymer was 1% by weight.
A composite hollow fiber membrane was prepared in the same manner as in Example 1 except that the test was conducted to produce a test membrane module. further,
Using the module coated with silicone in the same manner as in Example 1, an experiment for separating an organic liquid mixture was performed in the same manner as in Example 1. The separation factor was 2.33. The membrane permeation rate was 0.0226 kg / (m ² · hr).

Example 3 The solution concentration of the ionic group-containing polymer used was 0.01
A composite hollow fiber membrane was prepared in the same manner as in Example 1 except that the content was not more than 1% by weight, and a test membrane module was produced. Further, a separation experiment of an organic liquid mixture was performed in the same manner as in Example 1 using the module coated with silicone in the same manner as in Example 1. The separation factor is 2.3
It was 4. The membrane permeation rate was 0.050 kg / (m ² · hr).

Comparative Example 1 Average pore diameter 7.5 nm, outer diameter 1180 μm, inner diameter 780 μm
m of polyphenylene sulfide sulfone hollow fiber membrane
Cut to 0cm length, bundle 8 tubes, insert into glass tube mini module, potting both ends with epoxy adhesive,
A test membrane module was prepared. Further, the inner surface of the hollow fiber membrane of the test membrane module was coated with a crosslinked silicone solution. Coating method is to connect a silicone tube to the test membrane module and apply the crosslinked 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 of 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. The tolylene diisocyanate solution used was Tolylene diisocyanate coronate T-80 manufactured by Nippon Polyurethane Co., Ltd.
A weight% cyclohexane solution was prepared. 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 fed to the inside of the hollow fiber membrane at a flow rate of 0.2 m / sec 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 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 was calculated. The separation factor of the test membrane module was 1.81. The membrane permeation rate was 2.411 kg / (m ² · hr).

[0041]

According to the separation membrane and the separation method of the present invention, since the ionic group-containing polymer having silver ions as a counter ion is provided on the inner surface of the micropores of the membrane, the organic liquid has a higher separation coefficient. Some material can be removed from the mixture.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 9/15 C07C 9/15 15/04 15/04 C10L 1/00 C10L 1/00 (72) Inventor Yoshinari Fusaoka 1-1-1, Sonoyama, Otsu City, Shiga Prefecture F-term (reference) 4G006 HA25 HA01 HA18 HA21 HA41 HA61 HA61 HA71 KE01P KE05P MA01 MA02 MA03 MA09 MA10 MA22 MA33 MB04 MC02X MC22 MC23 MC26 MC28 MC29 MC30 MC33 MC39 MC61 MC61X MC65 MC68 MC74X MC75 NA44 NA46 NA64 PA02 PB13 PB20 PB68 PC80 4H006 AA02 AD19 4H013 AA03

Claims (12)

[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 an ionic group-containing polymer having silver ions present on the inner surface of pores of the porous support membrane as counter ions. 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 separation membrane for an organic liquid mixture according to claim 1, wherein the ionic group-containing polymer has a sulfonic acid group or a carboxylic acid group. 7. After contacting the porous support membrane with a solution of the ionic group-containing polymer, the solvent of the solution of the ionic group-containing polymer is removed, and further contacted with a silver ion aqueous solution;
A method for producing a separation membrane for an organic liquid mixture, wherein an ionic group-containing polymer having silver ions as a counter ion is formed on the inner surface layer of the pores of the porous support membrane. 8. After contacting the porous support membrane with a solution of an ionic group-containing polymer having silver ions as counter ions, removing the solvent of the solution of ionic group-containing polymers having silver ions as counter ions, A method for producing a separation membrane for an organic liquid mixture, wherein an ionic group-containing polymer having silver ions as a counter ion is formed on the inner surface layer of the pores of the porous support membrane. 9. An organic liquid mixture is supplied to one side of the separation membrane according to any one of claims 1 to 6, 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. 10. 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. 10. The method for separating an organic liquid mixture according to item 9. 11. The method for separating an organic liquid mixture according to claim 10, wherein the organic liquid mixture is gasoline containing an aromatic hydrocarbon. 12. A separation membrane according to any one of claims 1 to 6, which is disposed in a container, an organic liquid mixture supply section on one side of the separation membrane, and a permeated organic liquid withdrawal at a position opposite to the membrane. An organic liquid mixture separation device having a portion.