JPS6078601A - Composite separation membrane for pervaporation - Google Patents

Abstract

PURPOSE:To obtain the titled separation membrane having excellent separation property of an org. substance-aqueous system and org. permeability and capable of being formed into a thin membrane, by polymerizing or copolymerizing 1- monoalkyldimethylsilylpropine. CONSTITUTION:This composite separation membrane for the pervaporation of an org. substance-aqueous system is formed of an active layer comprising 1- monoalkyldimethylsilylpropine polymer having a repeating unit represented by formula (wherein R is one or more of an 1-12C straight chain or branched alkyl group) and a porous support layer. The M.W. of the polymer is pref. 100,000 or more. Various materials can be used as the porous support layer but substituted polyacetylene, polysulfone or polypropylene are pref. The thickness of the active layer is pref 20.0-0.05mum. As an org. substance capable of being separated from water by this separation membrane, there are water soluble ones such as lower alcohol, lower fatty acid, ketone, ether or amide. This separation membrane has a high permeation speed and practical strength as compared with silicone rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite separation membrane for organic substance-water pervaporation. Today, the technology of converting biomass into ethanol through fermentation is attracting attention as an energy alternative to petroleum that is being actively researched.
This is a low-concentration alcohol aqueous solution of 10 to 15%, and in order to increase the concentration of this low-concentration alcohol aqueous solution, conventional distillation operations require an enormous amount of energy, resulting in high costs. Therefore, membrane separation technology, which is an energy-saving separation technology, is being considered. First, conventional reverse osmosis membranes were considered, but because the reverse osmosis method passes a large amount of water through a separation membrane to separate water and alcohol, sufficient energy-saving effects cannot be expected.

Next, as a method for selectively permeating lower alcohols,
Wood et al. [MEMBRANE, 8 (3),
177-183 (1983)) proposed a pervaporation method using silicone rubber as a material. However, although this method is excellent in allowing alcohol to permeate selectively, there are problems such as the strength of the silicone rubber is poor and it is not possible to form a thin film to obtain a practical amount of permeation.

As a result of intensive research to overcome these problems, the present inventor has found that it has excellent organic substance-water separation properties and...
By making the active layer thinner, we have invented a composite membrane with excellent organic permeability.

That is, the present invention provides a 1-
This is a composite separation membrane for pervaporation of an organic matter-water system formed of an active layer made of a monoalkyldimethylsilylpropyne polymer and a porous support layer.

The active layer number represented by the general formula (1) in the present invention can be obtained by polymerizing or copolymerizing the corresponding 1-monoalkyldimethylsilylpropyne. As an example of a specific monomer, 1-
Examples include trimethylsilylpropyne, l-mono-n-propyldimethylsilylpropyne, ■-mono-n-hexyldimethylsilylpropyne, 1-mono-rhodecyldimethylsilylpropyne, and mixtures of two or more of these persimmons.

The monoalkyldimethylsilyl monomer used in the active layer of the present invention has excellent effects when the number of carbon atoms in the alkyl group ranges from 1 to 12, but the average number of alkyl carbon atoms is 1.1 in terms of separation of water and organic matter. -3.0, particularly preferably 1.2-
It is in the range of 2.0.

To polymerize these monomers, the method of bundle material, Masuda et al. (32nd Annual Conference of the Society of Polymer Science, Proceedings Vol.
Na3 page 181) and the method discovered by the present inventors (patent application ``Method for producing polymers'' May 1, 1981)
It can be done in 3 days). Specifically, one or more of these monomers are dissolved in aromatic hydrocarbons (benzene, toluene), alicyclic hydrocarbons (cyclohexane), halogenated hydrocarbons (1,2 dichloroethane), etc., and halogenated. Polymerization can be carried out in the presence of tantalum (TaX, . . . ) or halogenated (Nb×di) or triethylaluminum or the like if necessary.

The obtained monoalkyl (C1-Cl2) dimethylsilylpropyne polymer has a high molecular weight and an intrinsic viscosity (toluene solvent, 30°C) of 0.5 (dlV/F) or more. In addition to the polymerization solvents mentioned above, the polymer can be dissolved in aliphatic hydrocarbons (hexane, petroleum ether) and tetrahydrofuran.

If the molecular weight of the l-monoalkyldimethylsilylpropyne polymer used in the present invention is 10,000 or more in terms of weight average molecular weight (light scattering method), it will have excellent organic matter permeability and water-organic matter dispersibility. Preferably, those effects are better exhibited when the molecular weight is 500,000 or more, particularly preferably when the molecular weight is 100,000 or more.
More than 10,000. When the 1-monoalkyldimethylsilylpropyne polymer of the present invention is used as a pervaporation separation membrane, it is necessary to make the polymer into a thin film in order to obtain a practical permeation flow rate. Since it cannot maintain physical strength, it is necessary to use it in combination with a support.

The method for producing the composite film of the present invention can be carried out in accordance with the usual method for producing one composite film. Namely, (1) a method of coating on a porous support, (2) a method in which a thin film serving as an active layer is prepared in advance by a casting method or a water surface film, and
Method of adhering to a porous support (1) Particularly when the support layer and the active layer are made of the same polymer, an ordinary method for producing an asymmetric membrane can be adopted. That is, a dope is prepared by dissolving a 1-monoalkyldimethylsilylpropyne polymer at a fixed concentration (usually 1 to 10 weight percent) in the above solvent (single or mixed). This dope solution is applied onto a solid flat surface such as a glass plate, metal plate, plastic, etc., and after evaporating the solvent from the dope surface for a certain period of time, a non-solvent (for example, water, alcohols, ketones, acyclic ethers) etc. This is a method to create an asymmetric membrane with a two-layer structure, which has an active layer on the surface and a porous material on the bottom. Except for method (1), different polymers are generally used for the active layer and the porous support layer. As the porous support layer, in addition to commercially available porous membranes, such as microfiltration membranes (MF curtains), ultrafiltration membranes (IJF membranes), and reverse osmosis membranes (RO membranes), metal porous materials (stainless steel, nickel) can be used. , a porous ceramic material, and a porous glass material can be used, but especially when this porous material is composed of a substituted polyacetylene polymer, a polysulfone polymer, or a polypropylene polymer, the active layer 1-monoalkyl It was found that it has good adhesion to dimethylpropyne polymer and is highly practical. Examples of porous bodies of substituted polyacetylene polymers include
The same goes for the arylacetylene polymer semipermeable membrane described in Japanese Patent Application 1976-75976 "F Semipermeable Membrane and Manufacturing Method Thereof", which Hitotakata co-invented with Masuda of the Agency of Industrial Science and Technology, as well as other tert-butylacetylene vehicle combinations. It can be made into a semi-permeable membrane and can be used as a support layer in the present invention. 1-Phenyl-2- of the arylacetylene polymer semipermeable membranes
The semipermeable membrane made of chloroacetylene polymer had particularly good stability.

As a commercially available polysulfone membrane, the ultrafiltration membrane ■ series manufactured by Toyo Nito Paper (Sake) can be used.

As a commercially available polypropylene porous membrane, Duraguard 2
400 and 2500 (sold by Polyplastics)
etc. were suitable. One of the methods for creating an active layer of 1-monoalkyldimethylsilylpropyne polymer on these support layers is a coating method that can use a conventional coater, spray coating, spin coating, etc. . Further, a conventional casting group may be pressure-bonded to this support layer, and furthermore, an ultra-thin polymer film such as a water surface film may be used.

In the present invention, the thickness of the active layer of these 1-monoalkyldimethylsilyl polymers is usually 20 m 0.05 m, preferably 108 m 0.1 m. This thin film has excellent adhesion to the support layer, so it maintains sufficient stability, and because the active layer is thin, the permeation flow rate of organic matter to be separated is extremely large.

The pervaporation method using the composite separation membrane of the present invention can selectively permeate and separate water and soluble organic substances. Water-soluble organic substances include lower alcohols (methanol, ethanol, isopropanol, tertiary alcohols)
butanol, etc.), lower fatty acids (formic acid, acetic acid, etc.), ketones (acetone, etc.), ethers (dioxane, etc.), and amides (dimethylformamide, etc.).

As described above, the composite separation membrane according to the present invention selectively separates organic substances by the pervaporation method, can be formed into a thin film, has a significantly higher excess rate than silicone rubber, and has a practical strength. It has certain characteristics.

Hereinafter, the present invention will be specifically described using examples, but the invention is not limited thereto.

Production Example 1 (Polymer 11 (6) 0.2 mol of tolumethylsilylpropyne was added to toluene 100 + 1!, 1 mmol was added using TaclH as a catalyst, and polymerization was carried out at 80°C day and night. The resulting polymer gel was diluted with toluene. The polymer (A) was precipitated in methanol to obtain a white solid polymer (A).The weight average molecular weight determined by a light scattering method was 1.4 million.

(2) Polymer (B) Similarly, tolumethylsilylpropyne 0.15'mol and n
-Propyldimethylsilylpropyne 0.05 mol of mixed monomers are copolymerized to obtain a polymer (B). The weight average molecular weight determined by light scattering method was 1.1 million.

(3) Polymer (C) Similarly, tolumethylsilylpropyne 0.18 mo+ and n
A mixed monomer of 0.02 mol of hexyl-dimethylsilylpropyne is copolymerized. In this case, Ta as a catalyst
In addition to c151 mmol, 1 mmol of triethylaluminum is used as a cocatalyst. The obtained polymer (
The weight average molecular weight of C) was 1.15 million.

Examples 1 to 15 Comparative Examples 1' to 5' Polymers (A), (B), and (C) were combined with different porous support layers to create composite membranes as shown in Table 1. First, a 5% by weight toluene solution of the polymer is prepared. This dope solution is applied onto the porous support layer using a coater so as to have a casting thickness of 200 microns. At the same time, the same thickness was applied onto a glass plate, and the film thickness after drying was measured.

and 8.0μ. As the porous support layer, a semipermeable membrane of 1-phenyl-2-chloroacetylene polymer (hereinafter abbreviated as PPCA) (Japanese Patent Application Laid-Open No. 5657.5976), a polysulfone ultrafiltration membrane (hereinafter abbreviated as PS) (Toyo Roshi Company (manufactured)
U←50) and a polypropylene porous membrane (hereinafter abbreviated as PP) (Polyplastics Co., Ltd., Duraguard #2500) were used, respectively. For comparison, a composite membrane was prepared by using a polypropylene porous membrane in place of the polymers (A) to (C) and polydimethylsiloxane (Toshi Silicon 5H410) having a weight average molecular weight of 300,000.

[Pervaporation] 10% of ethanol, acetone, dioxane (as a water-organic liquid mixture)
Weight) Aqueous solution was used. The apparatus used was a flat membrane type ultrafiltration apparatus manufactured by Toyo Kagaku Sangyo (IV) with an effective membrane diameter of 45-1 (with a magnetic stirrer inside the cell) directly connected to a vacuum line.

Permeation experiments were conducted at 25°C. The degree of pressure reduction is 1. Q Torr
The permeate was collected in a trap cooled with liquid kiln. The permeate was collected for a certain period of time, and the flow rate (kg/4.h
) was calculated. On the other hand, the organic matter concentration of the permeate was determined by gas chromatography. The results of these experiments are also shown in Table 1.

Table 1 Examples 16-18 Polymers (A), (B), GC) were dissolved in petroleum ether to create a 0.5 weight percent solution.

A thin film was formed when 0.5 g of the solution was dropped onto the water surface.

The average film thickness is 0.2 from the film area of the produced thin film.
They were equal in μ.

A composite membrane was prepared using a PPCA semipermeable membrane as a support.

A pervaporation experiment using an aqueous solution of lθ% ethanol concentration was conducted in the same manner as in Examples 1 to 15. The results are shown in Table 2.

How to write a procedural amendment February 1st, 1980 1, Indication of the case 1986 Patent Application No. 186334 2, Name of the invention Composite component 111 membrane for pervaporation 3, Person making the amendment Relationship with the case Patent Applicant January 11, 19805, number of inventions increased by amendment6, application subject to amendment and specification...

Claims (6)

[Claims] (1) Activity consisting of a 1-monoalkyldimethylsilylpropyne polymer having a repeating unit represented by the general formula % formula % (wherein R is a linear or branched alkyl group of CI to C1l of li or more) A composite separation membrane for organic matter-water pervaporation formed from a layer and a porous support M. (2) Claim 1 in which the molecular weight of the 1-monoalkyldimethylsilylpropyne polymer is 100,000 or more.
Composite separation membrane as described in section. (3) The thickness of the active J- made of the polymer is 20-0.
The composite separation membrane according to claim 1 or 2, which is made of 0.05 μm. (4) The composite separation membrane according to any one of claims 1 to 3, wherein the porous support layer is a substituted acetylene polymer semipermeable membrane. (5) The composite separation membrane according to any one of claims 1 to 3, wherein the supporting layer is a porous polysulfone membrane. (6) The composite separation membrane according to any one of claims 1 to 3, wherein the support layer is a porous polypropylene membrane.