JPH0194904A - Production of hollow composite membrane for separating gas - Google Patents

Abstract

PURPOSE:To uniformize performance of the title membrane in the lengthwise direction by allowing a hollow supporter to be impregnated with either of the soln. of a compd. contg. amino group and the soln. of a multifunctional compd. and thereafter alternately supplying the residual soln. from both ends of the inner surface or the outer surface of the hollow supporter and forming the interfacial polymerized membrane. CONSTITUTION:The soln. of a compd. contg. amino group such as the ethylene glycol soln. of bis(aminopropyl)tetramethyldisiloxane is introduced into a polysulfone porous hollow supporter and this supporter is impregnated with this soln. by a press-fitting method. Then the soln. of a multifunctional compd. such as the hexadecene soln. of diphenylmethane diisocyanate is allowed to flow to the inner surface of the supporter from one end thereof and after cutting the liquid, the soln. of the multifunctional compd. is allowed to again flow to the opposite direction from the other end of the supporter and thereby both the compd. contg. amino group and the multifunctional compd. are subjected to interfacial reaction. Thereby a hollow composite membrane for separating gas in which an interfacial polymerized membrane is formed on the inner surface of the hollow supporter is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hollow fiber composite membrane for gas separation used to separate specific components from various mixed gases.

Conventional gas separation membranes have been proposed in various module shapes, such as a flat membrane, a spiral, and a hollow fiber. As a manufacturing method of the hollow fiber type module among these, the present inventors have disclosed Japanese Patent Application Laid-open No. 59-49089 and Japanese Patent Application No. 59-4908.
A film forming method using an interfacial polymerization method as shown in the specification of No. 9-43842 was proposed. According to the interfacial polymerization method, a thin film having gas selective separation ability can be formed on the inner or outer surface of a hollow support. However, it has become clear that because the reaction solution is supplied from one end of the hollow support, the performance of the membrane formed at the inlet and outlet of the reaction solution differs.

Object of the Invention The present invention provides a hollow fiber separation membrane having a gas selective separation thin film formed by interfacial polymerization on the inner or outer surface of a hollow support, which has uniform performance in the length direction of the membrane, and The object is to obtain a hollow fiber type module having excellent gas permeation characteristics.

Structure of the Invention The present invention provides the following steps when forming an interfacial polymer membrane having gas selective separation ability on the inner or outer surface of a porous hollow support.
After impregnating the hollow support with either the amino group-containing compound solution or the polyfunctional compound solution, when introducing the other solution onto the inner surface or the surface of the support, alternately from both ends of the hollow support. A method for producing a hollow composite membrane for gas separation, characterized in that the solution is supplied to a hollow composite membrane with an inner diameter of 50 to
The present invention relates to a method of contacting a reaction liquid to form a uniform gas selectively permeable thin film by interfacial polymerization on the inner surface of a porous hollow support having a diameter of 2000 μm and an outer diameter of 100 to 3000 μm.

The materials of the porous hollow support are polysulfone, polyethersulfone, cellulose acetate, cellulose, nylon 6, and polyacrylonitrile.

Examples include organic polymers such as vinyl chloride and polymethyl methacrylate, porous glass materials, sintered metals, and ceramics.

The average pore diameter of the surface of the hollow fiber support on which the permselective thin film is formed is 5 to 500 nl, preferably 7 to 100 nl.
It is nII. If it is smaller than 5nlD, the permeability is low (
, 500 nIg or more, it is difficult to obtain a membrane with selectivity, and the air permeation rate of such a support at 25°C is I x 104 ~ 5 cc/aa Hsec +
cmHG, preferably lX104 to 0.5 CC/d-
8eC-cIIHg. I x 10' cc/
Below cl ・f + Bc - cs + Jl, the permeability is low and impractical, and 5 cc/cd -sec
・■ If it exceeds HQ, the strength of the support decreases and it tends to become unusable.

Further, the maximum pore diameter of the inner or outer surface of such a support is 0.5 μm or less, preferably 0.2 μm or less.

The thickness of the gas selectively permeable thin film formed on the inner or outer surface of the hollow support is 5nl11 to 3μm, preferably 10nI
It is 1 to 1 μm.

An interfacial polymerization method is used as a method for forming such a gas selectively permeable thin film. In the interfacial polymerization method, an amino group-containing compound having at least two primary and/or secondary amino groups, an organic liquid that is freely miscible with water, or a mixture of such an organic liquid and water is used. A solution of an undissolved amino group-containing compound and a polyfunctional compound having at least two functional groups capable of reacting with the amino group-containing compound or its solution are prepared, and one of the compounds is prepared in a porous state in a solution state. After the hollow support is impregnated, the other compound is introduced inside or outside the support in solution or gaseous form to cause a reaction between the two compounds inside or outside the hollow support, and thus the gas Forms a permselective thin film.

Compounds having at least two primary and/or secondary amino groups include aliphatic polyamines such as ethylenediamine and polyethyleneimine, alicyclic polyamines such as cyclohexanediamine, aromatic polyamines such as metaphenylenediamine, bis( Examples include siloxane-containing polyamines such as (aminopropyl)tetramethyldisiloxane.

Further, as the polyfunctional compound, a compound having at least two isocyanate groups or acid chloride groups is used.

The compound having two isocyanate groups or acid chloride groups is not particularly limited, but preferably has 4 carbon atoms.
-15, particularly preferably 6-13 polyisocyanates or polyacid chlorides are used. Specific examples include polyisocyanates such as toluylene diisocyanate, 4,4°-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, and acid chlorides such as isophthalic acid chloride, trimellitic acid chloride, and adipic acid chloride. be able to.

The solvent for the amino group-containing compound is preferably water or a liquid that is arbitrarily miscible with water, particularly water.

Methanol, ethanol, isopropanol, methylcellosolve, dioxane, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, or a mixed solvent of two or more thereof is preferable, and the amine is 0.1 t/100 (preferably 111 or more). 0
．． It is preferable that 5 g/100 ml or more is soluble.

The concentration of the amino group-containing compound is 1001113
1 to 10 ft%, preferably 5Qoppn+ to 5 wt%
It is.

As the solvent for the polyfunctional compound, a solvent that forms an interface with at least one of the solvents for the amino group compound is used, preferably an aliphatic hydrocarbon having 6 to 18 carbon atoms, or a halogenated hydrocarbon. It is hydrogen, and specific examples include n-hexane, n-hebutane, n-octane, cyclohexane, n-decane, n-tetradecane, hexadecene-1° carbon tetrachloride, trifluoro-1-lichloroethylene, etc. . The concentration of polyfunctional compounds is 50 ppm
~5wt%, preferably '1ooppn+~3wt%.

As a method for impregnating the hollow support with the amino group compound or polyfunctional compound, any method such as a dipping method, pressurized injection method, vacuum suction method, etc. may be used, but it is necessary to sufficiently impregnate the inside of the porous material. It is important to A preferred method is to create a pressure difference between the inner and outer surfaces of the hollow support membrane and impregnate the hollow support from the inner or outer surface.

After impregnating a support with a solution of either an amino group-containing compound or a polyfunctional compound, the liquid in the hollow part is drained, or
Alternatively, by introducing a solution of the other compound without removing the liquid, the reaction proceeds at the interface of the two liquids, forming a gas selectively permeable thin film.

When forming an interface, a dipping method, pressurized injection method, vacuum suction method, etc. can be used to introduce the solution, but the pressure difference between the inner and outer surfaces of the hollow support should be equal or 0.1k.
The flow rate of such an interfacial solution, which preferably has a micropressure difference of less than g/min, is less than 60 m/ntin, preferably less than 10 m/l1in.

60m/li! If it exceeds n, the interface will be disturbed and a good film will not be obtained.

Such interfacial reaction between the amino group-containing compound and the polyfunctional compound is carried out at a temperature of 0 to 100°C, preferably 10 to 50°C, for 5 seconds to 10 seconds, preferably 10 seconds to 5 minutes.

In such an interfacial reaction, if the solution is introduced from only one end of the hollow support, the concentration of the compound in the solution changes in the length direction as the reaction progresses, resulting in different performances at the inlet and outlet sides of the solution. An interfacial film is formed. In order to prevent this, the solution is introduced from one end of the hollow support and then flowed in the opposite direction from the other end, and the ratio of the time for flowing in one direction and the time in the opposite direction is preferably 100:1 to 1:100. The ratio is 10:1 to 1:10. Alternatively, the operation of flowing in the opposite direction and then changing the direction of flowing may be repeated.

Change the flow direction 1 to 5 times, preferably 1 to 5 times.
Three times. If it is repeated more than 5 times, even if the direction is changed, the uniformity will not be further improved, and the operation will become complicated, which is undesirable.
The reaction and the concentration of the compound in the solution run each time may be the same or different, and the solvent of the reaction solution run each time is preferably the same, but may be different.
The flow rate and reaction temperature of the reaction solution may be the same or different each time.

In this way, a hollow composite membrane is obtained in which a FiF membrane having gas selective permeability is formed on the inner or outer surface of the hollow support. Further, if necessary, the remaining solvent, amino group-containing compound, and polyfunctional compound are washed away, and the hollow composite membrane for gas separation of the present invention is obtained by drying.

Effect The hollow composite membrane for gas separation of the present invention can be used to separate various gases by utilizing its excellent permeation amount per unit volume and excellent selectivity.For example, the hollow composite membrane for gas separation can be used for the separation of various gases. It can be incorporated into a combustion furnace, engine, etc. to improve combustion efficiency, and can be used as a treatment device for people with respiratory disorders, and can be used for industrial purposes to efficiently separate various gases such as hydrogen and carbon monoxide.

The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

In the examples, "parts" indicate parts by weight.

Reference Example 1 (Production method of polysulfone hollow porous support) 20 parts of polysulfone (Nichikagaku, Udel P3500).

A solution consisting of 57 parts of N-methyl-2-pyrrolidone, 3 parts of lithium chloride, and 20 parts of 2-methoxyethanol was prepared, and the solution was discharged from an annular slit using water as a core liquid at 30°C, and then poured into water at 25°C. It was immersed in and solidified.

A polysulfone hollow porous support having an outer diameter of 800 μm and an inner diameter of 500 μm was thus obtained. This hollow support was packed into a polycarbonate pipe and both ends were solidified with an adhesive to obtain a hollow fiber membrane module. 25℃ of this hollow fiber membrane when drying
The amount of air permeation at is IXtO((cc(STP)
/al-3ec-ca+HG), which is an appropriate value for gas permeability.

After introducing the 0.15 wt% ethylene glycol solution of Example 1 into the hollow porous support shown in Reference Example 1, a pressure of 1 kg/d was applied from the inside using nitrogen, and the ethylene glycol solution was introduced into the porous support at 1 kg/d. It was pressed in for a minute.

Thereafter, the liquid on the inner surface of the hollow support was drained with nitrogen gas, and a 300 ppm hexadecene solution of diphenylmethane diisocyanate was applied to the inner surface of the hollow fiber support at 25° C. from one end of the hollow support at 1 m/m! After flowing at a flow rate of n for 1 minute and draining with nitrogen gas, a 300 ppm hexadecene solution of diphenylmethane diisocyanate was again flowed for 1 minute from the other end of the hollow support. After draining the remaining liquid on the inner surface of the hollow support again, it was washed under running water for one day to wash away the ethylene glycol, and then thoroughly dried to obtain a composite membrane. Table 1 shows the overall performance and partial performance in the longitudinal direction of this membrane.

Comparative Example 1 In Example 1, the diphenylmethane diisocyanate solution was not supplied alternately from both ends of the hollow support, but was only supplied continuously for 2 minutes from one end, but the other conditions were exactly the same as in Example 1. A membrane was obtained. Table 1 shows the overall performance and partial performance in the longitudinal direction of this membrane.

Example 2 A film was formed in exactly the same manner as in Example 1, except that the concentration of diphenylmethane diisocyanate was 100 pfull the first time and 300 ppn after reversing the flow direction. The overall performance of this membrane is shown in Table 2.

Example 3 In Example 1, a tetradecane solution of toluylene diisocyanate (TD I ) was used instead of the hexadecene solution of diphenylmethane diisocyanate, and the first TDIi degree was set to 1501) l) The flow direction was reversed at 1 m for 1 minute. Thereafter, a membrane was obtained in exactly the same manner as in Example 1 except that the reaction was carried out at 250 pH for 3 minutes. The overall performance of this membrane is shown in Table 2.

Comparative Example 2 A membrane was obtained in the same manner as in Example 3, except that the TDI concentration was 25 ppH, the flow was carried out in one direction for 3 minutes, and the conversion was not performed. The overall performance of this membrane is shown in Table 2.

Example 4 Everything was the same as in Example 1, except that instead of introducing the polyamine solution into the inner surface of the hollow fiber support in Example 1, it was introduced into the outer surface, and thereafter all operations on the inner surface in Example 1 were performed on the outer surface. The overall performance of this membrane is shown in Table 2.

Comparative Example 3 A composite membrane was obtained in exactly the same manner as in Example 4, except that a solution of diphenylmethane diisocyanate was supplied from one end to the outer surface for 2 minutes and the inversion operation was not performed. The overall performance of this membrane is shown in Table 2.

Claims (1)

[Claims] When forming an interfacial polymer membrane having gas selective separation ability on the inner or outer surface of a porous hollow support, a solution of an amino group-containing compound or a solution of a polyfunctional compound that reacts with the compound to form a polymer is used. After the hollow support is impregnated with one of the solutions, the remaining solution is alternately supplied from both ends of the inner surface or the outer surface of the hollow support to form an interfacial polymer film. A method for manufacturing a hollow composite membrane for gas separation.