JPS5888009A - Separation of liquid mixture - Google Patents

Abstract

PURPOSE:To carry out efficient operation, in separating or concentrating an org. liquid mixture through pervaporation, by using a membrane comprising a copolymer of fluorinated olefin and fluorinated vinyl ether. CONSTITUTION:In separating or concentrating a mixture comprising org. liquids or an org. liquid and water, by using a high molecular membrane comprising a copolymer of carboxylic acid derivative type fluorinated vinyl, fluorinated olefin and fluorinated vinyl ether, operation excellent in the efficiency of separation or concn. and a permeation speed is enabled. An operation temp. is selected from a range of 0-200 deg.C and pressure from a range of 0-100kg/cm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for separating or separating a liquid mixture containing at least an organic liquid as one of its components (hereinafter abbreviated as an organic liquid mixture) by pervaporation using a specific polymer membrane. Concerning the method of concentrating.

A process for separating organic liquid mixtures using non-porous, uniform polymeric membranes has been previously described in U.S. Pat.
This is taught in Specification No. 2, etc. This separation process is generally called a pervaporation process using a membrane, in which the liquid to be treated is supplied to the primary side (high pressure side) of the polymer membrane, and substances that are easily permeable are fed to the secondary side (low pressure side). This is a method of preferentially transmitting it as vapor. This membrane separation method separates or concentrates liquid mixtures that could not be separated using conventional simple methods, such as azeotropic mixtures, mixtures with close boiling points and low relative volatility, and mixtures containing substances that polymerize or modify when heated. It is attracting attention as a new way to do so.

Conventionally, the polymer membranes used in such separation methods are polyethylene and polypropylene.

Cellulose polymer materials, polyacrylonitrile, polyamide, polyester, polystyrene.

Membranes made of polytetrafluoroethylene or copolymers thereof are known. However, when an organic liquid mixture is separated by pervaporation using a certain type of membrane, the following practical difficulties are recognized. That is, (1) The rate of concentration (separation coefficient α) caused by the organic liquid mixture passing through the polymer membrane once is small, so in order to concentrate or separate the organic liquid mixture to the desired concentration, it is necessary to pass through the polymer membrane once. must pass through the membrane. In general, the separation factor α
, is as follows.

(2) Since the amount of permeation of an organic liquid mixture through a polymer membrane (generally expressed as the permeation amount per unit membrane surface area, unit membrane thickness, and unit time) is small, the membrane surface area must be made very large or The thickness of the molecular membrane must be made extremely thin. Therefore, in the former case, the equipment cost becomes excessive.

In the latter case, problems arise in the strength and durability of the membrane.

As the above-mentioned improved process, a method using a polymer membrane in which sulfonic acid groups etc. are bonded to a polymer base, a method using a specific polyamide membrane, a method using an ionomer polymer membrane, etc. are disclosed in Japanese Patent Application Publication No. It is disclosed in Japanese Patent No. 52-111888, Japanese Publication No. 52-111889, Japanese Publication No. 54-33278, Japanese Publication No. 54-33279, etc.

The present inventor has conducted various studies on means of separating or concentrating various organic liquid mixtures by pervaporation.
As a result of repeated studies, we found that fluorinated olefinic metals such as tetrafluoroethylene, specific fluorovinyl compounds that have carboxylic acid type functional groups, and fluorovinyl ether compounds that do not have acid type functional groups such as perfluoropropyl vinyl ether. It has been found that a polymer membrane made of a copolymer with

That is, the present invention provides a liquid mixture having at least an organic liquid as one of its constituent components.
' is a fluorine atom or a perfluoroalkyl group having 1 to 10 carbon atoms, l is 0 to 3, m is 0 to 1,
n is 0 to 12, and A is -CN, -COF, -COO
Hl-COORI, -cooej-M or -CONRI
R'', R' is an alkyl group having 1 to 20 carbon atoms, M is a metal atom or -NR4R'Re R?, X is the valence number of M, and R1, Rm.

A fluorovinyl compound having an acid type functional group represented by R4, Hs, He and H1d hydrogen atoms or 1 dll), a fluorinated olefin compound, and a fluorinated olefin compound having mW in the molecule.
The present invention provides a novel method for separating liquid mixtures, which is characterized by separation by pervaporation using a polymer membrane made of a copolymer with a fluorovinyl ether compound that does not have a functional group.

In the present invention, the fluorovinyl compound constituting the specific polymer membrane has the following formula: Here, X%Y, Y', l, m, n, and A are as above, but from the viewpoint of performance and availability, X is -F, Y is 10F,,Y' is -F, l is 0~
1, m is preferably O-1, and n is preferably 0-8. Although A is not particularly limited, -COF and -COOR' are preferred from the viewpoint of ease of copolymerization. A preferable representative example from this point of view is CF, =CF
O(CF, ). %,C00CH,,CF,:CFO
(CF, ). ,, Cot, OF, =CFOCF
, CF(CF, )OCF.

CF, COF%CF, ==CF OCF, CF(
CF, )OCF, cy, 1COOCH,, CF2=
CF (CF, ). -, -COOCH, and the like.

In addition, A in the specific polymer membrane of the present invention is appropriately selected depending on the organic liquid mixture to be subjected to barbeverageation, and is a metal atom such as the MH alkali metal or alkaline earth metal. Or -NR'R'R6R' is exemplified.

Further, as the fluorinated olefin compound used in the present invention, preferably a compound represented by the following general formula can be mentioned.

CF, = CZZ' where 2 and z'H1-p', -C1, -H or -
CF. Typical examples include tetrafluoroethylene, chlorotrifluoroethylene, propylene hexafluoride, ethylene trifluoride, vinylitine fluoride, vinyl fluoride, and the like. Catemo and perfluoroolefin compounds are preferred, and tetrafluoroethylene is particularly preferred.

Next, as another monomer compound of the present invention, the fluorovinyl ether compound, is a fluorine-containing vinyl ether compound that can be copolymerized with the above-mentioned fluorovinyl compound and fluorinated olefin compound, and representative preferred examples thereof include:
It is expressed by the following general formula.

CF, =CX − (OCF, CFY) bi(0), −
(CFY')n-B\, where X, Y, Y', l, m and n are the same as above, and B is a fluorine atom, a hydrogen atom,
A chlorine atom, a difluoromethyl group or a trifluoromethyl group. Furthermore, l and m never become 0 at the same time. Among them, X is -F, Y is -CF, Y' is -F
, 1 is preferably 0-1, m is 0-1, n is O-8, and B is -F. A preferred specific example of the fluorovinyl ether compound is as follows.

deha, barfluoromethyl vinyl ether, no(-fluoropropyl vinyl ether, 3,6-thioxer 4-
Examples include methyl-7-octene.

In the present invention, two or more of the above compounds are used as a constituent unit of a fluorine-containing copolymer having a specific carboxylic acid type functional group (hereinafter abbreviated as carboxylic acid type fluororesin). In addition to these, other components such as olefin compounds such as ethylene, propylene, and imbutylene, CF, ==CF -CF -
CF, ,CF,=CFO(CFz)t~, 0C
One or more types of divinyl monomers such as F=CF and other functional monomers containing sulfonic acid type functional groups can also be used in combination. It is possible to modify the copolymer as appropriate, such as by using divinyl monomer in combination to crosslink the resulting copolymer.

In the present invention, the content of the fluorovinyl compound having a specific carboxylic acid type functional group is related to the performance as a polymer membrane, especially the ion exchange capacity described below, and is preferably 0.1 in the carboxylic acid type fluororesin. ~50 molti, especially 1~
About 40 molti may be employed. Further, the content of the fluorovinyl ether compound that does not have an acid type functional group is related to particularly the mechanical performance of the polymer membrane, and is preferably about 1 to 60 molar, particularly about 2 to 20 molar.

Means for carrying out the copolymerization include peroxy compounds, with or without inert organic or aqueous solvents;
Known means such as carrying out the reaction under the action of a polymerization initiator such as an azo compound, a Shiba ray, or an ionizing radiation can be employed. For example, Japanese Patent Publication No. 48-2223, Japanese Patent Publication No. 48-207
It can be carried out by the method described in Japanese Patent Publication No. 88 and Japanese Patent Publication No. 48-41942. As for the polymerization method, various methods such as bulk polymerization, solution polymerization, suspension polymerization, and precipitation polymerization can be adopted.

The fluorine-containing copolymer of the present invention may be a graft copolymer or a block copolymer, but the carboxylic acid type functional groups are uniformly dispersed in the copolymer.

A copolymer obtained by directly copolymerizing each of the monomer compounds described above is particularly preferable, since a polymer membrane having a uniform ion exchange capacity can be obtained.

In the present invention, means for forming a polymer membrane from a fluorine-containing copolymer having a specific carboxylic acid type functional group (hereinafter abbreviated as carboxylic acid type fluororesin) as described above may be any known means, For example, press molding, roll molding, extrusion molding, solution casting, dispersion molding, powder molding, etc. are used.

In the present invention, the content of the carboxylic acid type functional group in the carboxylic acid type fluororesin can be adopted over a wide range;
In a preferred embodiment, the ion exchange capacity described below is 0.01.
Selected from a wide range of ~3 meq/g dry resin. The ion exchange capacity is preferably Uo, 1 to 2.
Approximately 2 milliequivalents/gram dry resin is employed. Also,
From the viewpoint of mechanical strength as a polymer membrane, the molecular weight of the carboxylic acid type fluororesin is expressed as -T, which will be described later.
The temperature is preferably 50°C or higher, preferably about 70 to 300°C.

In this specification, the term "T" is defined as follows. That is, the temperature at which the volumetric flow rate 10[]-/sec, which is related to the molecular weight of the polymer, is defined as T. In this case, the volumetric flow rate is determined by using a polymer in which the carboxylic acid type functional group is a -COOCHs group, and melting the polymer from an orifice with a diameter of 1 m and a length of 2 mm at a constant temperature under a pressure of 30 kp/cd. It is expressed in units of weight of polymer flowing out/second.

In addition, the 1 ion exchange capacity was determined as follows. That is, a carboxylic acid type fluororesin having a carboxylic acid type functional group of 1-C0OH group is left at 60°C for 5 hours or more in 1N HCI to completely convert it to the iCH type, and then it is completely converted to the iCH type, and is thoroughly diluted with water so that no MCI remains. Washed. After that, this H-type resin 0.
The sample was left standing at room temperature for 2 days in a solution of 59't-10, 1N NaOH25- and water 25-. The resin was then taken out and the amount of NaOH in the solution was reduced to 0.1N HC.
It is determined by back titration with I.

The carboxylic acid-type fluororesin of the present invention may be made of an olefin polymer such as polyethylene or polypropylene, preferably a fluorine-containing copolymer such as polytetrafluoroethylene or a copolymer of ethylene and tetrafluoroethylene, if necessary during film formation. The copolymer can be blended and molded, or the membrane can be reinforced by supporting the copolymer with a support made of cloth, net, or other woven fabric, nonwoven fabric, or porous film made of these polymers. . Nao, ka\
The weight of the resin forming the blend or support is not included in the above ion exchange capacity values.

The polymer film made of carboxylic acid type fluororesin used in the present invention is a non-porous uniform film, and the film thickness is 1 to 25 mm.
0 micron, preferably about 5 to 180 microns. If the film thickness becomes too thin, the film may lack strength or durability. Furthermore, if the membrane is too thick, the amount of permeation of the liquid mixture becomes small, making it impractical. The shape of the polymer membrane is usually a flat membrane, but it can also be used in other shapes such as a cylindrical shape or a hollow fiber shape to increase the surface area. Furthermore, various reinforcing means may be applied, such as embedding a reinforcing material such as a cloth in the membrane, or laminating the membrane on a porous reinforcing body.

The method of the present invention uses the above-mentioned carboxylic acid type fluororesin membrane, -
It is carried out using a device that is divided into a secondary chamber and a secondary chamber.

- the next chamber contains the organic liquid mixture to be separated or concentrated in liquid form, while the secondary chamber is reduced in pressure by a suitable method;
or circulating other liquids or gases. In this manner, the organic liquid mixture is permeated through the polymer membrane and separated or concentrated by pervaporation. - The liquid inside the next chamber is preferably circulated externally or internally, or - agitated by providing a suitable stirring device inside the next chamber. The specific polymer membrane is held in a suitable manner to partition the primary chamber and the secondary chamber, but supporting it with a reinforcing porous plate, for example, is advantageous in terms of durability. - Substances that permeate the polymer membrane from the next chamber are taken out from the second chamber and collected. It is usually desirable to appropriately heat the secondary chamber and/or the secondary chamber using a suitable heating device, such as a heating jacket.

The separation method of the present invention is carried out over a wide range of temperatures, typically from 0 to 200°C, preferably from room temperature to 100°C.
Selected from a range of degrees.

If the temperature is too high, problems will arise in maintaining the shape of the polymer membrane, and if the temperature is too low, the amount of liquid permeated will be small. Generally, the amount of permeation can be increased at high temperatures, but the concentration ratio (separation coefficient) due to membrane permeation becomes smaller. Further, the pressure range that can be employed is normally from vacuum to 100 #/m, preferably from vacuum to 30 kp/cr/, and if the pressure is too high, it becomes difficult to maintain the shape of the polymer membrane.

The organic liquid mixtures that can be separated by the method of the present invention include various combinations, such as mixtures of organic substances that cannot be separated by normal distillation methods due to the presence of azeotropic points, and mixtures of organic substances whose boiling points are close to each other. This is particularly effective in the case of mixtures of organic substances that are difficult to separate by distillation due to their presence. Further, the organic liquid mixture may be entirely dissolved in each other uniformly, or a part of the organic liquid mixture may exceed the solubility and precipitate into a suspended state.

However, the organic liquid mixture needs to be in a liquid state in its mixed state within the above-mentioned implementation temperature range and at normal pressure or within the adopted pressure range.

Examples of such organic liquid mixtures include benzene/cyclohexane and benzene/n as mixtures having an azeotropic point.
- mixtures of organic substances such as hexane, methanol/acetone, benzene/methanol, acetone/chloroform; water/isoglopanol, water/ethanol, water/n
-Propanol, water allyl alcohol water/2-methoxyethanol, water/isobutanol.

Water/n-penshio-nol, water/2-butanol, water/furfuryl alcohol, water/n-penshio-nol, water/2-penshio-nol, water/4-methyl-1-penshio-nol, etc.
Alcohol mixture; water/tetrahydrofuran, water/dioxane.

Examples include water/organic solvent mixtures such as water/methyl ethyl ketone.

Also, as mixtures whose boiling points are close to each other, ethylbenzene/styrene, cycloethylbenzene/p
-Chlorstyrene, toluene/methylcyclohexane,
Examples thereof include butadiene/butenes, butadiene/butenes, n-butene/+-butene, and the like. Other examples include water/glycerin, water/glycols, water/propylene chlorohydrin, water/propylene dichlorohydrin, water/epichlorohydrin, water/hydrazine, and isomer mixtures.

Furthermore, the method of the present invention can be applied to these mixtures not only in the above two-component systems but also in multi-component systems, such as ternary or more. Of course, the method of the invention can also be applied to mixtures containing organic and inorganic substances, such as wastewater containing organic liquids.

The mixing ratio of the liquid mixture to be treated can be changed within an arbitrary range, but in general, the closer the ratio is to the equivalent situation, the higher the concentration ratio will be. If the desired purity cannot be obtained by passing through a polymer membrane once (-membrane concentration), pass it through a similar device multiple times (multi-stage concentration).
, the organic liquid mixture can also be concentrated or separated to a desired extent.

Examples of the present invention will be described in more detail below, but it goes without saying that the present invention is not limited by such explanations.

Example 1 In a 200 at stainless steel pressure-resistant reaction vessel, 20,!
CF2 of M = CFO(CFt)s coocHs
, 4-511 no CF, : CFOC, F7 and 181
1 of trichlorotrifluoroethane and 76 g of azobisisobutyronitrile were charged. After sufficiently degassing with liquid nitrogen, the temperature was adjusted to 70°C, and 16.5
A copolymerization reaction was carried out by charging kf/Cl1i.

After 20 hours, 9.5 g of copolymer was obtained. The copolymer was press-molded at 180°C to form a film with a thickness of 100μ, which was then hydrolyzed with caustic soda and diluted with pure water at 90°C for 1 hour.
treated for 6 hours, then dried at 70"C for 24 hours,
A polymer membrane with an ion exchange capacity of 0.92 meq/g was obtained.

Pervaporation using an iron membrane A mixed solution of water and isopropanol (impropanol/water = 82/1
8, weight ratio] were separated. Temperature 40℃, permeate side pressure 1
The separation coefficient of water for ingropanol obtained at 0 mmHg is 26.2, and the permeation amount u272
It was Ji'/m"hr.

Example 2 CF, = 61.5 g of CF instead of CFO(CFt)a C00CHs, = CFOCF, CF(
A copolymerization reaction was carried out under the same conditions as in Example 1, except that CF, )O(CF, )scooc)I was charged. After 20 hours, the ion exchange volume to, 80 m
A copolymer with mq/1/ was obtained. The copolymer was press-molded at 180°C to form a film with a thickness of 100μ, then this film was hydrolyzed in caustic soda, the functional group was changed to -COOH type in hydrochloric acid, and the film was heated in pure water at 90°C. Treated for 16 hours, then dried at 70°C for 24 hours.

Using the obtained membrane, a mixture of water and ethanol (ethanol/water = 94/6, weight ratio) was separated by pervaporation at 40°C.

The separation coefficient for nine Koushio nols obtained at 10-' mmHg was H6.85, and the amount of permeation was 730 tons.
/m”・hr.

Example 6 A copolymerization reaction was carried out under the same conditions as in Example 1, except that 6.4P of C = CFOCF, CFCF3 -QC,F was charged in place of CF, = CFOC, F7. After 20 hours, the ion exchange capacity was 0.
A copolymer t-10.5% of 93 meq/y was obtained. The copolymer was formed into a film with a thickness of 100 μm by press casting.

The film was hydrolyzed in lithium hydroxide and diluted with pure water at 9%
After processing at -0-°C for 16 hours, it was dried at 70°C for 24 hours to obtain a film with -COOLi type functional groups. As a result of conducting a separation experiment similar to Example 2 using an iron membrane, the separation coefficient and permeation amount were each 5.52.570 p/m! -hr
Met.

Procedural amendment form) 1985-Monday, Japan Patent Office Commissioner Haruki Shimada1, Indication of the case, Patent Application No. 185529 of 19832, Name of the invention Method for separating liquid mixtures 3, Person making the amendment Case and Relationship Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (
004) Asahi Glass Co., Ltd. 6. Number of inventions increased by amendment None 7. Subject of amendment Specification

Claims (1)

[Claims] A liquid mixture having at least an organic liquid as one of the 70 constituents is defined by the general formula CF, =, CX-Φc5cpy)t-(
ol, -(CFY')n-A (where, X is a fluorine atom or -〇F3, Y and Y' are a fluorine atom or a perfluoroalkyl group having 1 to 10 carbon atoms, and l is 0 to
3, m is 0 to 1, n is 0 to 12, and A
i -CN, -Q)F, -COOH, -COOR'
,-Co.・1M or -〇〇NR'R3, where R1 has 1 or more carbon atoms
20 alkyl group, M is a metal atom or --NR'
R'R'R', X is the valence number of M,
R2, 13, R4, R11, He and R1 are hydrogen atoms or R1], a fluorinated olefin compound, and a fluorinated olefin compound having an acid type functional group in the molecule. A method for separating a liquid mixture, characterized in that the separation is performed by pervaporation using a polymer membrane made of a copolymer with a fluorovinyl ether compound.