DD283637A5 - IONENAUSTAUSCHMEBRAMEN - Google Patents

Abstract

The invention relates to ion exchange membranes prepared from an organic polymeric material which is preferably perfluorinated and contains a polymeric chain and at least one chain branching from the chain, the chain branching from the chain being a saturated cyclic group and at least one ion exchange group or group can be converted to one containing and containing the ion exchange group or group which converts to such is attached via the cyclic group to the polymeric chain. The ion exchange membrane is suitable for an electrolytic cell, especially a chloralkali cell. organic polymer material; electrolytic cell; polymeric chain}

Description

Field of application of the invention

The invention relates to ion exchange membranes containing an organic polymer material, especially an ion exchange membrane for an electrolytic cell, especially a chloroalkali cell.

Characteristic of the known state of the art

Ion exchange membranes made from organic polymer materials having ion exchange properties are used in an ever-increasing variety of applications. These polymeric materials and membranes may contain fixed anionic groups and associated cations and be capable of cation exchange, or may have fixed cationic groups and associated anions and thus be capable of anion exchange, or the polymer materials and membranes may contain both fixed anionic groups and fixed cationic groups

Ion exchange membranes are suitable for separation processes such as reverse osmosis and ultrafiltration. You will find ζ. Β Widely used in the desalination of sea water and for the purification of brackish water and industrial wastewater, ion exchange membranes also find wide applications in the industry, eg. B. in the enrichment of solutions, von B. of fruit juices and pharmaceuticals

Ion exchange membranes, which are substantially hydraulically impermeable but permeable to cations or anions, or both, find growing applications in electrochemical cells, e.g. In recent years, there has been a significant development in the use of cation exchange membranes in chloroalkali cells wherein chlorine and aqueous alkali metal hydroxide are produced by electrolysis of aqueous alkali metal chloride solution In such a chalice cell, a cation exchange membrane is placed between an anode and an adjacent cathode, and during electrolysis cations are transported through the membrane between the anode compartment and the cathode compartment of the cell. When an aqueous solution of alkali metal chloride is electrolyzed in such an electrolytic cell, the solution Im is added to the anode compartment of the cell and the chlorine produced during the electrolysis and the spent alkali metal chloride solution are withdrawn from the anode compartment while hydrated alkali metal ions pass through the membrane into the cathode compartment of the cell where water or dilute alkali metal hydroxide solution is charged, and hydrogen and alkali metal hydroxide solution produced by the reaction of alkali metal ions with water are withdrawn from the cathode compartment of the cell. In general, the alkali metal chloride is sodium chloride, but it may also be potassium chloride

Although many organic polymeric materials have been proposed as membranes for such electrochemical cells, perfluoroorganic polymers containing ion exchange groups, especially fixed sulfonyl and carboxy groups, have been used in recent years, preferably for chloroalkali cells, because such perfluoroorganic polymers are resistant to chemical degradation in the cell.

An example of a perfluoroorganic polymer containing ion exchange groups and proposed as an ion exchange membrane is the perfluoroorganic polymer containing sulfo groups described in British Patent 1034197. The perfluoroorganic polymer can be ζ B units of the structure

-CF ₂ -CF ₇ - and

-CF ₂ -CF-

(OCF ₂ CFY) _n OCF ₂ CFR (SO ₂ M

wherein Rf is fluorine or a perfluoroalkyl group having 1-10 carbon atoms, ζ B is a perfluoromethyl group, η is 1,2 or 3, Y is fluorine or a trifluoromethyl group, and M is fluorine, a hydroxy group, an amino group or a group of

Formula OMet is wherein Met is an alkali metal or a substituted or unsubstituted ammonium group The use of such a perfluoroorganic polymer as an ion exchange membrane in a chloroalkah cell is described in British Patent 1402920. Polymers of the type described are described as membranes under the tradename "Nafion" by EI DuPont de Nemours Inc. In a preferred perfluoroorganic polymer of the above structure, Y is CF ₃ , η 1 and Rf F.

Another example of a perfluoroorganic polymer containing ion exchange groups and also proposed as an ion exchange membrane is a perfluoroorganic polymer containing carboxy groups and described in British Patent Nos. 1516048 and 1518387. Examples of such perfluoroorganic polymers are copolymers of tetrafluoroethylene and

CF ₂ = CF-O-CF ₂ -CF (CF ₃ K) -CFr-CFr-CF ₂ -COX, CF ₂ = CF-O- (CF ₂ ) _S -O-CF (CF ₃ ) -COX, CF ₂ = CF-O- (CF ₂ ) 4 -O-CF (CF ₃ ) -COX and CFi = CF-O-CF ₂ -CRCF ₃ K) -CF ₂ CF ₂ -COX,

wherein X z. Fluorine, a hydroxy group, an alkoxy group or a group of the formula OM wherein M is an alkali metal or a quaternary ammonium group. Polymers of the type described are sold under the tradename "Flemion" by Asahi Glass Co. Ltd.

Many different types of perfluoroorganic polymers and combinations thereof have been proposed as ion-exchange membranes in chloroalkali cells, and those described above are given by way of example only. Membranes of polymers containing both carboxy and sulfo groups have been proposed as well as membranes composed of laminates of two or a plurality of films of different polymers, ζ B is a laminate of a film of a perfluoroorganic polymer containing sulfo groups and a film of a perfluoroorganic polymer containing carboxy / groups.

Most polymeric materials proposed as ion-exchange membranes for chlor-alkali cells and all polymer materials used commercially in such cells are perfluoroorganic polymers, i. h Polymers containing ion exchange groups in which the polymer is fully fluorinated so that the organic polymer does not contain carbon atoms bonded hydrogen atoms. It has been found very desirable that the polymer material be a perfluorinated polymer if it has sufficient stability and resistance to chemical attack Degradation in the environment of a chloralkali cell, especially in the presence of wet chlorine, chlorine-containing aqueous alkali metal halide solution and aqueous alkali metal hydroxide solution. In general, the proposed perfluoroorganic polymers were copolymers of tetrafluoroethylene and a perfluorovinyl ether containing one or more ion exchange groups.

Object of the invention

The invention provides an ion exchange membrane containing a novel organic polymeric material which finds particular application in an electrolytic cell

Explanation of the essence of the invention The invention has for its object to provide a new organic polymer material, the

containing ion exchange groups and is suitable for use as an ion exchange membrane.

According to the present invention, there is provided an organic polymeric material comprising a polymer chain and at least

contains a group leaving the chain, wherein the group leaving the chain contains a saturated cyclic group and at least one of an ion exchange group or group which converts to it, and wherein the one or more groups of the ion exchange group or group which can be converted thereto cyclic group is attached to the polymeric chain.

The inventive organic polymer material is particularly suitable as ion exchange membrane, and in a

In another embodiment of the invention, an ion exchange membrane is disclosed which contains an organic polymer material as described in the form of a near hydraulic impermeable film or film. The ion exchange membrane is permeable to ions which may be solvated, e.g. B. hydrated, but hydraulically almost impenetrable.

The ion exchange membrane is especially suitable as a membrane in an electrolytic cell, though not on these Use is limited, and in a further embodiment of the invention, a cell is presented, the at least one Anode and at least one cathode, and an ion exchange membrane as described, which between an anode

and a neighboring cathode, thus dividing the cell into separate anode and cathode spaces

The organic polymer material according to the invention can be obtained by polymerizing at least one vinyl monomer with a

saturated cyclic group and an ion exchange group or group which can be converted into such and which is bonded via the cyclic group to the vinyl group, or by copolymerization of at least one of them

Vinyl monomer with an ethylenically unsaturated monomer that does not contain an ion exchange group or a group that forms in

such a "; and / or with at least one vinyl monomer containing an ion exchange group or

Group which can be converted into such contains, which are not bound via a cyclic group to the vinyl group

is to be received.

The copolymerization can be carried out in the presence of an ethylenically unsaturated monomer which does not contain an ion exchange group or Group which can be converted into such, take place in the chain of the organic polymer material To introduce units which do not contain an ion exchange group or group which can be converted into such, and

which may serve to modify the properties of the organic polymer material and the membranes made therefrom, especially the physical and / or mechanical properties of the membrane and the ion exchange capacity thereof.

The organic polymeric material according to the invention, especially in the form of an ion exchange membrane, has a number of advantages and advantages. For example, it is possible to have more than one ion exchange group or group that can be converted into such as part of a side group or each side group attached to the polymer material, thereby making it possible to vary the ion exchange capacity of the organic polymer material, especially Increase, in particular, increase the proportion of units in the organic polymer material which are derived from the vinyl monomer and contain the ion exchange group or groups which can be converted into these. Specifically, it is possible to have a relatively high ion exchange capacity at one In addition, in the organic polymer material, the ion exchange groups or groups which can be converted into those are bonded to the polymer chain via a cyclic group, and it isby suitable arrangement of the ion exchange groups or groups which can be converted into those bonded to the cyclic groups, and by suitable arrangement, substituents other than ion exchange groups and bonded to the cyclic groups change the ion exchange activity of the former groups vary. For example, if the cyclic group has the cyclohexyl structure and has a single ion exchange group or group that converts to one such group, then that group can be located in the 2-, 3- or 4-position, thereby increasing the activity of a particular such group can be varied.

Preferably, the organic polymer material is a fluoropolymer material because such materials are generally more resistant to chemicals, acids and alkalis, with which they may come into contact in use. Indeed, as a polymeric organic material, a perfluoropolymer material is preferred for many purposes. Thus, in a chloroalkali cell where chlorine and aqueous alkali metal hydroxide solution are produced by electrolyzing aqueous alkali metal chloride solutions, an ion exchange membrane of perfluoropolymer material is preferred because such membrane is particularly resistant to chemical attack by the electrolyte and electrolysis products In the side group or side groups of the organic polymer material, the cyclic group is saturated, ie it does not contain ethylenic unsaturation. Although we do not exclude the possibility that the organic polymer material contains some side groups containing unsaturated groups, e.g. B unsaturated cyclic groups, the presence of such unsaturated groups may be detrimental, especially when the organic polymer material is used as an ion exchange membrane in a chloroalkali cell. When used as a membrane in a chloroalkali cell, such unsaturated groups may undergo chemical attack, e.g. Chlorination of the unsaturated group and species-closing chemical attack by alkali. Therefore, the cyclic groups in the organic polymer material should preferably consist of saturated groups.

The organic polymer material may contain a fixed cationic group, i. h is a cationic group bonded to the group leaving the polymer chain and an associated anion, whereby the polymer material is an anion exchange material. On the other hand, the organic polymer material may contain a fixed anionic group and an associated cation, whereby the polymer material is a cation exchange material. Materials of the latter type generally have broader applications, especially as an ion exchange membrane for electrolytic cells. It is also possible for the organic polymer material to contain both fixed cationic groups and fixed anionic groups, as well as the associated anions and cations, such that the polymeric material acts both as an anion exchange material as well as a cation exchange material acts.

When the polymeric material is a cation exchange material, suitable fixed anionic groups are those of the sulfo, carboxy and phosphonic acid type

For example, the group may have the structure -SO ₂ X, where X is OM and wherein M is H or an alkali metal, ζ. Β is sodium or potassium, or an ammonium or quarternary ammonium group but X can also be halogen, z. Fluorine, in which case the group -SO, X is not itself capable of ion exchange. The latter group can be hydrolyzed to convert it into a group that is itself capable of ion exchange. The group may have the structure COY wherein Y is OM and wherein MH is an alkali metal, eg, sodium or potassium, or an ammonium or quaternary ammonium group. However, Y may also be halogen, e.g. B may be fluorine, or alkoxy, in which case the group -COY is not itself capable of ion exchange. The latter group may be hydrolyzed to convert it to a group which is itself capable of ion exchange.

Suitable anion exchange groups or groups which can be converted into these are, inter alia, groups which contain quaternary ammonium, for example a group N (AlClI) ₄ X, in which X is a halogen, ζB.-CH ₂ N (CHa) ₃ ⁺ Cl "or -CH ₂ -NH-CH ₂ CH ₂ N (CH ₃ U ⁺ Cr) For convenience, the term "ion exchange group" will be used hereinafter for both ion-exchangeable and ion-exchangeable groups but can be converted, for example, by hydrolysis, into groups capable of ion exchange.

The cyclic group in the groups leaving the polymer chain of the organic polymer material may be a carbocyclic or heterocyclic group and may contain 4,5 B of 4.5 or 6 atoms. Suitable carbocyclic groups are e.g. B. Cyclohexyl or Cyclopentyl Type Groups Suitable heterocyclic groups may be oxygen or nitrogen containing, examples being a tetrahydrofuran group or a piperidyl group.

The ion exchange group may be directly bonded to the cyclic group which is part of the group leaving the polymer chain of the organic polymer material, or it may be indirectly linked to the cyclic group via a divalent group. Direct attachment of the ion exchange group to the cyclic group provides more latitude for varying the activity of the ion exchange group, ζ B by altering the binding portions of the ion exchange group on the cyclic group and / or by attaching other groups to the cyclic group whose presence is 2-u However, if the ion exchange group is of the carboxy type, the direct attachment of the ion exchange group to the cyclic group is not preferred, especially if the organic polymer material comes in contact with caustic alkali , B. when serving as an ion exchange membrane in a chloroalkali cell, since the alkali metal may tend to decarboxylate the polymer material. Indirect bonding of the carboxy group to the cyclic group is preferred because polymeric materials containing such indirectly bonded groups are less susceptible to decarboxylation.

The organic polymer material may contain ion exchange groups of one type or may be ion exchange groups

a variety of types included. Thus, the polymer chain of the organic polymer material may contain side groups containing an ion exchange group of one type, and side groups containing one ion exchange group of the other

Type or the polymer chain may contain side groups, of which at least several

Contains ionic shear groups that may be different or the same

ion exchanger groups can be located at the same group of sands, a high ion exchange capacity of the

organic polymer material is achieved without requiring a high proportion of groups derived from the vinyl monomer and containing the ion exchange groups

The cyclic group may be attached directly or indirectly via a divalent group to the polymer chain of the organic Polymer Maerials be bound The organic polymer material may be a polymer chain of units of the structure

-CA ₂ -CA ₂ - and ethers of the structure

-CA ₂ -CA-B

wherein A is hydrogen, halogen or alkyl and wherein the groups A may be the same or different, and wherein the group B is a group containing a saturated cyclic group and an ion exchange group and wherein the ion exchange group via the cyclic group to the polymer chain is bound. For reasons already stated above, preferably at least a portion of the groups A is F, and it is more preferred that all groups A are F and that group B is also fluorinated, preferably perfluorinated. Examples of group B are as follows.

wherein the cyclic group is saturated, wherein D and E may be the same or different and represent divalent groups or a single bond, wherein the cyclic group may be a hydrocarbon or may be partially or fully fluorinated, and wherein η is an integer of at least 1. For example, η may be 1 or 2.

The group B may be a group of similar structure, but in which the group DSO ₂ X is replaced by the group (DCOY) n, that is.

-в. - ^{ШУ) ·

The cyclic group may also contain one or more groups - (DSO ₂ X) _n and one or more groups - (DCOY) _n , ie. that group B is the structure

Examples of such groups B are the following.

• DCOy

X and Y are as defined above. If D is a divalent group, it may e.g. B. - (CAj) _n - wherein A is as described above. In case of a

Preferably, the group D is a divalent group for the reasons given above for the carboxy-type ion exchange group.

The group O can z. B. -CF ₇ , as in

Cf ₁ SO ₁ X

-в-Г)

or as in

-о

- p

The group E, via which the cyclic group is bonded to the polymer chain of the organic polymer material, can be a Be single bond or a divalent group. It can be the same as or different from group D and can be one Ethergruppo include, r. B. a group - (OCF ₂ -CFRf) _n -, wherein η is an integer, z. Example, 1,2 or 3, and Rf F or one Perfluoralky! Group is Other cyclic groups to which are bonded directly or indirectly ion exchange groups are ζ B. groups of

structure

wherein Z is O or IM and D and E are as defined above and the cyclic group is partially or fully fluorinated, as well as groups in which -DSO ₂ X is replaced by-DCOY are examples of such groups

worm R is an alkyl group which may be perfluorinated

The ion exchanger activity of the ion exchange groups may be due to the presence of non-ionic

Can be varied ion exchange groups on the cyclic groups. Suitable such nonionic exchange groups are e.g. Alkyl Cities, Especially Perfluoroalkyl Groups The relative position of the non-ion exchange groups to the ion exchange groups on the cyclic group has an effect on the ion exchange activity of the ion exchange group.

In the polymeric material, the units containing a group leaving the chain of polymeric material,

which contain a cyclic group and an ion exchange group bonded thereto by polymerization of a

Vinyl monomer containing such a cyclic group and an ion exchange group. The vinyl monomer

For example, the structure may have CA ₂ = CA-B, where A and B have the structures described above.

The organic polymer material can be obtained by copolymerization of suitable monomers, e.g. B. by Copolymerization of an olefin as described above having the structure

CA ₂ = CA ₂

with a vinyl monomer as described above with the structure CA ₂ = CA-B

The organic polymer material may be prepared by known polymerization methods, by solution polymerization or dispersion polymerization. The polymerization may be under elevated pressure, in fact, the use of increased pressure may be critical if a gaseous olefin is to be copolymerized, e.g. For example, tetrafluoroethylene wherein CA ₂ = CA ₂ AF in the olefin, and the polymerization can be initiated by known methods, ζ B by a radical generator, ζ B. a peroxide. The polymerization can be carried out at elevated temperature. The precise conditions under which the polymerization must be carried out depend, at least in part, on the precise nature of the monomers to be polymerized.

By way of example only, some vinyl ether monomers containing a cyclic group and an ion exchange group attached thereto are presented below and which are polymerized to form units in the organic polymer material of the present invention.

Exemplary embodiments Such examples are

and CF ₂ CF- (OCF ₂ -CF) _n -O-CF ₂

wherein the -SO ₂ -X group may be in the 2-, 3- or 4-position, the cyclic group is fully fluorinated and saturated and η is an integer of 1 to> 3 (F within the cyclic group means the group is perfluorinated) In other specific examples of suitable vinyl ether monomers, the -SO ^ X group can be replaced by the group-CF ₂ COY

Examples of vinyl ether monomers containing a cyclic group and a plurality of ion exchange groups attached thereto are

CP ₀ = CP- (O-CP ₀ -CP) -OC? ^

wherein η is an integer of 1 to 3 and the cyclic group is fully fluorinated and saturated, and the isomers in which the -SOr-X groups are in the 2,6- and 3,5-position

 Other examples are

w- ₀ - ν L KJ OjJ

wherein the cyclic group is fully fluorinated and saturated The method of preparation of the vinyl monomer containing a cyclic group having an ion exchange group bonded thereto depends on the kind of the vinyl monomer to be represented. The illustration of various vinyl monomers which can be polymerized into the organic polymer material of the present invention will now be described Examples of some of the vinyl monomers and intermediates in the preparation of the monomers are novel and stand-alone invented materials and form part of the present invention. In each case, the preparation of the vinyl monomer from a known starting material will be described. A Representation of a perfluorinated monomer of the structure

SO ₂ P

from pentafluorobenzoic acid, wherein η is zero or an integer. COOH comes with a solution? of NaSH in aqueous NaOH

70 ° C into

COOH

implemented.

2. The thiol group in COOH

is then oxidized to COOH by reaction with a solution of hydrogen peroxide in acetic acid.

3. COOH is then added to the disourefluoride by reaction

SO ₃ H with SP, to COP

! KT

SO ₂ P

implemented.

4. CO? v, 'is there in by Pluorierunc of CO?

SO ₂ P with a gas mixture of F ₂ / N ₂ in a fluorocarbon solvent

Alternatively, COP can also be obtained by electrochemical pluoring

SO ₂ P are represented by COCl.

SO ₂ Cl

5. COP is then added with hexafluoropropylene oxide

SO ₂ P

CP ₂ O (CP (CP ₃ ) CPpO) _n CPCO? implemented, -togin η O or one

SO ₂ P

is an integer, orto a mixture wherein η is 0 and an integer η is generally 0,1,2 or 3, depending on the ratio of the reactants

6. СЖ1 (C? (CP -.) CPpO) CP = CPp v / ied then by pyrolysis of

С? _о 0 (СР (С? т) С? р0) "СРС0Р at 240-400 ⁰ C in the D-rrof phase

J ^{2 3 2 n} |

SOP?

or at 120-18OX in the liquid phase.

B. Representation of a perfluorinated monomer of the structure

? (GFj) CF

from perfluorobenzaldehyde, wherein

η is O or an integer. 1. ОНО becomes with rhodanine too

implemented.

Il j *

2 The product from Step 1 is then added by reaction with a solution of potassium permanganate in water, CCOH

implemented.

3. The product of step 2 is then fluorinated with SF ₄ to the disulfur fluoride "COP.

"SO ₂ P

• COP is then mixed with a Fp / Np gasgenically

a fluorocarbon solution with too

COP fluorinated

Alternatively, you can

ѲС

O? also by implementation of

SO ₂ P ООН with SP. to

CO? and then

SO ₂ ?

electrochemical fluorination? being represented. 5. _л / ч ^ COF "is then mixed with hexafluoropropylene oxide or chlorine

pentafluoropropylene oxide too

₂ O) _n CP

Rf

итдевеШ, wherein Rf-CFe or-Ch ^ Cl and η is 0 or an integer, or to a mixture wherein η is 0 and an integer η is generally 0,1,2 or 3, depending on the ratio the reaction partner.

-14- 283637! CP (Rf) ₂ O CP) CP = CP ₂ is da ¹ ^ djrch pyrolysis

CP-CO? under the ones described above

Conditions shown

Some of the vinyl monomers and the intermediates used to form these monomers are part of the present invention, and in one embodiment of the invention, there is presented an intermediate containing a perfluorinated six membered carbocyclic ring having two or more acidic groups or derivatives thereof, at least two of which have a different structure The six-membered ring can be saturated or unsaturated and can ζ B the

structure

COY

or is a saturated derivative thereof, wherein X is O, wherein M is H or alkali metal, ammonium or quaternary ammonium or X is halogen, and Y is OM, wherein M is H or alkali metal, ammonium or quaternary ammonium, or Y is halogen or alkoxy Structure are

SO ₀ X

SO ₂ X

COY and saturated derivatives thereof ζ B.

SO ₂ OH

COP

COOH

and saturated derivatives thereof

Also part of the present invention is a fully saturated intermediate of the structure

wherein Rf is F or perfluoroalkyl and wherein π is 0 or an integer, or a mixture wherein η is 0 and an integer, and wherein X is as defined above A vinyl monomer of the structure

worm Rf F is the perfluoroalkyl and wherein η is 0 or an integer, or a mixture wherein η is 0 and an integer, and wherein X is as defined above, is also part of the invention

 C. Representation of a perfluorinated monomer of the structure

CP ₉ O (CF (CF 2) CF ₀ OV CF = CF,

с. j с.ηi

wherein η is 0 or an integer

The following reaction sequence is used in the preparation of this monomer.

COOH PSO ₂ ' ^ c / ' COP

COP - Z - > PSO ₂ - ^ ⁴ O '^ CF ₂ O (CF (CF ₃ ) CF ₂ O) _n CFCOF

- ~> PSO ₂ - ^v 0 ^/ ^ CP ₂ O (CP (CF ₃ ) CP ₂ O) _n CP = CP ₂ ,

worm η is 0 or an integer or a mixture of zero and an integer, and wherein the reaction steps a to e are the following

a SF ₄ at 80 "C

b F2 / N2 in a fluorocarbon solvent or electrochemical fluorination с hexafluoropropylene oxide / CsF in tetraglyme

d vapor phase pyrolysis

The membrane according to the invention is in the form of a thin film or film of the organic polymer material. The film or film can be produced by a number of different methods of known type for producing films or films of organic polymer material. For example, a membrane in the form of a film or a film Films may be formed by melt extrusion of the polymer material through a suitable opening or by calendering the polymer material on a pair of rotating rollers or by precipitating a solution of the organic polymer material onto a suitable substrate. The thickness of the membrane depends at least to some extent on the nature of the membrane should be used. However, for many purposes, a thickness of the film or film is between 50 and 500 μm. The ion exchange capacity, ie. the concentration of ion exchange groups in the organic polymer material and in the ion exchange membrane may also vary over a wide range. It is determined by the way the membrane is to be used. Suitable ion exchange capacity of the organic polymer material and membrane is in the range of 0.4 although ion exchange capacity may also be outside this range, the ion exchange membrane in the form of a thin film or film of the organic polymeric material may be coated on a film or film of a similar or different organic polymeric material, containing the ion exchange groups, be laminated.

Although the ion exchange membrane of the present invention may be used for a wide variety of purposes, ζ B in fuel cells and in the enrichment of solutions, it is particularly useful as an ion exchange membrane in an electrolytic cell, and the invention provides a cell comprising at least one anode and comprising at least one cathode and an ion exchanger auschermembran as described, which separates an anode and an adjacent cathode from each other and thus divided the electrolytic cell into separate anode and cathode spaces The electrolytic cell may be a monopol.jre cell containing a plurality of separate anodes and cathodes or it may be a bipolar cell containing a plurality of electrodes, one side functioning as an anode and the other as a cathode. The electrolytic cell may be used for the electrolysis of a wide variety of materials but is particularly useful for the electrolysis of aqueous alkali When an aqueous alkali metal chloride solution in an electrolytic cell with an ion exchange membrane is electrolyzed, the solution is fed to the anode compartment of the cell and the chlorine formed during the electrolysis and the consumed catalyst

Alkali metal chloride solutions are derived from the anode compartment, the alkali metal ions are transported through the membranes to the cathode compartments of the cells where water or dilute alkali metal hydroxide solution can be added and hydrogen and the alkali metal hydroxide solution formed by reaction of the alkali metal ions with water are drained from the cathode compartments of the cells

The electrodes in the electrolytic cell are basically made of a metal or an alloy, the type of which depends on whether the electrode is to be used as an anode or as a cathode, and on the nature of the electrolyte to be electrolyzed in the cell

When aqueous alkali metal chloride solution is to be electrolyzed and the electrode is to be used as an anode, the electrode is suitably made of a film-forming metal or an alloy thereof, zirconium, niobium, tungsten or tantalum, preferably of titanium, and the surface of the anode suitably carries one Coating of an Electroconductive Electrocatalytically Active Material The coating may contain one or more platinum group metals, ie, platinum, rhodium, indium, ruthenium, osmium, or palladium, and / or an oxide of one or more of these metals The coating of the platinum group metal and / or the oxide of which may be in admixture with one or more oxides of base metals, especially one or more film-forming metal oxides, e.g. B titanium dioxide. Electrically conductive electrocatalytically active materials as anode excesses in an electrolytic cell for the electrolysis of aqueous alkali metal chloride solutions and methods for the application of such coatings are known.

When aqueous alkali metal chloride solutions are to be electrolyzed, the cathode is conveniently made of iron or steel or other suitable metal, ζ B nickel. The cathode may be coated with a material which reduces hydrogen overvoltage during electrolysis

In the electrolytic cell, the anode compartments are provided with means for supplying the electrolyte, preferably from a common collection tube, and with devices for discharging the electrolysis products. Similarly, the cathode compartments are with devices for discharging the electrolysis products and optionally with devices for supplying water or other liquids, preferably For example, using the cell for the electrolysis of aqueous alkali metal chloride solution, the anode compartment is provided with means for supplying the aqueous alkali metal chloride solution and devices for dissipating chlorine and optionally with devices for discharging spent alkali metal chloride solution, and the cathode compartment is provided with devices for the removal of hydrogen and Zellflussigkeit containing Alkalimetallhydroxidlosung, and optionally if necessary with means for supplying water or dilute alkali metal hydroxide solution,

The invention is illustrated by the following examples

example 1

Preparation of 4-sulfo-tetrafluorobenzoic acid

COOH

SO, H

424 g (2.0 mol) of pentafluorobenzoic acid are added while stirring to 160 g (4.0 mol) of sodium hydroxide in 2 l of water to give a clear solution. Then 200g NaSH (70% flakes, corresponding to 140g [2.5 mol] NaSH) was added and the resulting mixture was heated with stirring to 7O ⁰ C After 2 h stirring at 7O ⁰ C, the formed yellow solution is cooled in ice and washed with neutralized The resulting white slurry is extracted with 4x500 ml of ether, the extract dried over MgSO ₄ and the ether removed on a rotary evaporator The white powder formed is dried in vacuo at 80 ° C and provides 407g 4-Mercaptotetrafluorbenzoesaure,

in a yield of about 90%.

The structure of the product is confirmed by IR, NMR and mass spectra. The above process steps were repeated to recover a supply of 4-mercapto-tetrafluorobenzoic acid intended for further reaction.

440 g of 4-mercapto-tetrafluorobenzoic acid are dissolved in 1700 ml of glacial acetic acid. The solution formed is added to heated with stirring in a water bath at 80 ⁰ C and within 2 hours 800 ml of a 30% (w / VoI) aqueous hydrogen peroxide solution was added dropwise The resulting solution is cooled to 20 ⁰ C and to decompose excess hydrogen peroxide 68g of sodium metabisulfite

The resulting solution is evaporated in a rotary evaporator at 80 ° C in vacuo and gives a bright orange solid. The solid is added in 260ml water gel and 60ml concentrated hydrochloric acid. The resulting solution is added

extracted with 1 χ 600 гг I and 3x 250ml ethyl acetate, and the isolated product is then back-extracted by rubbing in the combined ethyl acetate extracts with 1 x 500ml and 3x 250ml water in water.

The water is removed on a rotary evaporator to give an off-white powder which is dried at 80 ° C and 0.7 mbar to give 322 g of the product 4-sulfo-tetrafluorobenzoic acid (yield 66%). The structure of the product is determined by infrared, NMR and mass spectrum confirmed

Example 2

Preparation of 4-fluorosulfonyl perfluorocyclohexane carboxylic acid fluoride

C07

SO ₉ p

100 g of 4-sulfo-tetrafluorobenzoic acid, prepared as described in Example 1, are heated to 8O ⁰ C in a 500 ml Hasteloy autoclave with 100 ml of thionyl chloride for 1 h. The excess thionyl chloride and the SO ₂ and HCl formed in the reaction of the thionyl chloride with water are removed in vacuo. The autoclave is then cooled with liquid nitrogen and 78 g of SF _{4 are} distilled into the autoclave. The autoclave is then heated to 20 ⁰ C and the stirring started the autoclave is then heated to 80 ⁰ C. for 18 h, then cooled and vented. The product, a brown liquid, solidifies on standing. The product is dissolved in CF ₂ CICFCb, treated with dry NaF to remove traces of HF, and the solution is filtered. Gas chromatography and mass spectrography indicate that the solution is 4-fluorosulfonyl-tetrafluorobenzoyl fluoride and 45-fluorosulfonyl-heptafluorotoluene in yields of ca. Contains 70 and 10%, respectively, as confirmed by infrared and NMR analysis.

4Qg 4-fluorosulfonyl-tetrafluorobenzoyl fluoride, which is separated from the above solution by distillation, and 850 ml of CFjCICFCfe are placed in a glass reactor with Kuhler, Intensivruhrer and Kuhlbad The reactor contents are cooled to -35 ° C, and a 50/50 Vol. Mixture of F ₂ / N ₂ is passed through the reactor at a rate of 50 ml / min. The temperature of the solution in the reactor is kept at -35.degree. After 30 hours, gas chromatographic analysis shows no trace of + -fjjorsulfonyl-tetrafluorobenzoyl fluoride in the solution and the presence of 4-fluorosulfonyl perfluorocyclohexanecarboxylic acid fluoride

and perfluorocyclohexane carboxylic acid fluoride COP

The 4-fluorosulfonyl perfluorocyclohexane carboxylic acid fluoride is separated from the solution by distillation and its structure is confirmed by infrared and NMR analysis.

Example 3

Preparation of 4-fluorosulfonyl perfluorocyclohexane carboxylic acid fluoride

CO?

by electrochemical fluorination of 4-chlorosulfonyl-benzoyl chloride COCl

SO ₂ Cl

An 11-Simons cell is charged with 800 g of anhydrous hydrogen fluoride and the cell is operated at 5.0 V for 19 h to dry the electrolyte. To the dry electrolytes 48 g of 4-chlorosulfonylbenzoyl chloride are added in one portion and the electrolysis at 6, 0 continued V and a cell temperature of 20 ⁰ C. After 24 h, the lower layer consisting of flussigen fluorocarbon products (18 g) is derived from the cell and treated with solid Natriumfluond to remove excess hydrogen fluoride. is

0354 ^ 0 ^^ 71 ^ 6 ^ 0 ^ 010116x31103 ^ x ^ 330 ^ 11.10 ^ is separated from the liquid fluorocarbon mixture by distillation, and its structure is confirmed by mass spectrographic and NMR analysis

Example 4

display of

С7 «0 (C? (CF-) CF ₉ O) CFCOF

SC ₂ F

17.6 g of 4-fluorosulfonyl-perfluorocyclohexanecarboxylic acid fluoride prepared as described in Example 2 are added to 20 ml of dry tetraglyme containing 0.24 g of dry cesium fluoride in a 125 ml autoclave. The resulting mixture is left for half an hour under an atmosphere of dry nitrogen stirred, then cooled to -60 ° C, then the autoclave is evacuated, and 20 g of hexafluoropropylene oxide are distilled in the autoclave. The mixture is then allowed to warm to room temperature and stirred overnight. The upper fluorocarbon layer (20 g) is recovered and found to be gas chromatographic and mass spectrographic analysis mainly as a mixture of products of the above formula wherein η is 0 and 1 in the ratio of about 5: 1. The structure of the product is confirmed by mass spectrographic and infrared analysis

Example 5

display of

To 200 ⁰ C preheated nitrogen as the carrier gas is passed through a heated oil bath at 220 ⁰ C evaporating flask. 20 g of the product from Example 4 are injected dropwise into the evaporation flask by means of an injection pump at a rate of 0.8 ml / min. The resulting gas stream is passed from the bottom to a 15 cm high fluidized bed of 100 cm ³ 60 mesh glass beads at 340 ^° C. The flow rate is chosen to achieve a contact time of about 10 seconds, and the fluorocarbon products (11.2 g) are condensed from the exhaust stream into a series of cooling traps. The major product proved to be mass spectrographic and infrared spectrographic

wherein η = 0, and some product of the above structure with η = 1 The product contains a small amount of an adduct of the above structure with HF.

Example 6

Preparation of an organic polymer material with ion exchange groups or groups which can be converted into these

15 g of a distilled fraction of the product shown in Example 5, which according to gas chromatographic analysis 98%

O) _n CF = CF ₂

is placed in a 0.51 jacketed autoclave with gas inlet, stirrer and thermocouple, and 200 ml of deionized water, 0.2 g of ammonium persulfate and 0.3 g of ammonium perfluorooctanoate are also added to the autoclave. The autoclave is then alternately evacuated and rinsed with nitrogen to remove air and the mixture in the autoclave is carried 2stundiges stirring at room temperature in a nitrogen atmosphere emulsified the autoclave is evacuated again and charged with tetrafluoroethylene to a pressure of 10 bar and then slowly with stirring at 8O ⁰ C heated. The autoclave is pressurized with new tetrafluoroethylene each time the pressure has dropped below б bar until the accumulated pressure drop indicates the uptake of 15g of tetrafluoroethylene. The autoclave is cooled, vented and the emulsion removed. A small amount (4.5 g) of perfluorovinyl ether settles out as the lower layer and the remaining emulsion is frozen to recover the copolymer formed. The copolymer is filtered off, washed with deionized water and dried at 80 ^° C. under reduced pressure, 16 2g of white copolymer. A sample of the copolymer is hot-pressed, and is a clear, solid film, the infrared peak at 1460cm ^'1 is (SO ₂ F) A 200μηι thick hot pressed film of the copolymer is dissolved in a 25% solution of NaOH in aqueous ethanol ( 75% H ₂ O, 25% EthanoJ) hydrolyzed at 75 ° C for 12 h, resulting in a film which, according to titration, has an ion exchange capacity of 0.9 meq / g

Example 7

Preparation of organic polymer material with ion exchange groups or groups that can be converted into these (Altei natiwerfahren)

10 g of a distilled fraction of the product shown in Example 5, which according to gas chromatographic analysis 93%

CF ₀ O (CF (CP-JCF ₀ O) OP = CF,

ιC. J C.Πс

contains, in 200 ml of CF ₂ CICFCI ₂ containing 0.1 g Azoisobutyronitnl dissolved and added the solution in a jacketed 400 ml autoclave with gas inlet, Ruhrer and thermocouple. The autoclave is sparged with nitrogen, evacuated, and tetrafluoroethylene is added to the autoclave to a pressure of 10 bar. The autoclave is heated to 75 ^C C and the contents stirred Each time the pressure has dropped below 8 bars, new tetrafluoroethylene is printed until the collected printed waste identify a shot of 10g tetrafluoroethylene Then the autoclave is cooled and recovered the CopolymenJispersion formed. The copolymer is filtered off, washed with CF ₃ CICFCIj and dried in vacuo at 8O ⁰ C to give 5.6 g of white powder. Infrared examination of a hot-pressed film from the powder shows absorption at 1460 cm ^-1 (-SO ₂ F).

Example 8

Preparation of 2-sulfo-tetrafluorobenzoic acid

and 2-fluorosulfonyl-tetrafluorbenzoy) fluoride

38 g of methylamine are added dropwise to a well-stirred suspension of 50 g of rhodanine and 70 g of pentafluorobenzaldehyde in 100 ml of chloroform, the temperature being kept below 4O ⁰ C by external cooling. After one hour, the solution is washed first with dilute HCl, then with water. The solvent is removed and the remaining yellow residue is recrystallized from IMS / water to give 82 g of 2,3,4,5,6-pentafluorobenzylidene-rhodanine, F 132 ° C-135 ° C 78g 2,3,4,5,6-Pentafluorbenzylidenrhodanin be added in small portions to a stirred solution of 68g NaOH in 300ml of water. The clear red solution formed is heated for 1 h at 90 ⁰ C, cooled in ice, acidified with concentrated HCl and The resulting cream-colored solid was filtered off and washed. The crude product (59 g) is purified by sublimation to yield 4,5,6,7-tetrafluorobenzothiophene-2-carboxylic acid, F.200 ° C.

A solution of 158 g of KMnO ₄ in 1.5 L of warm water is added to a stirred slurry of 49.7 g of 4,5,6,7-tetrafluorobenzothiophene-2-carboxylic acid and 27.6 g of K ₂ CO ₃ in 200 mL of water at such a rate that the temperature is maintained at 50 ⁰ C. After completion of the addition, the mixture 3 hours at 10O ⁰ C heated, then cooled and the MnO ₂ removed by filtration the filter cake is washed with hot water and the combined aqueous phases acidified with concentrated HCI

The aqueous phase is concentrated on a rotary evaporator at 8O ⁰ C under vacuum to a moist slurry This slurry is extracted several times with ethyl acetate, the combined organic phases dried over MgSO ₄ , filtered and the solvent removed to give 23.5 g of product are obtained after identification of the ¹⁹ F, ¹³ C and ¹ H-NMR and rnassenspektrographischen analysis is benzoic acid 2-sulfo-tetrafluoi.

14.6 g of 2-sulfo-tetrafluorobenzoic acid are boiled with 64 g of thionyl chloride for 5 h, then cooled to room temperature and diluted with 100 ml of methylene chloride. Filtration and removal of the volatiles in vacuo yielded 6.6 g of an orange gum which was identified as the anhydride by ¹⁹ F and ¹³ C NMR and infrared analysis

ГЛІ

proves

8.0 g of the crude anhydride, dissolved in 20 ml of dry methylene chloride, are placed under nitrogen in a warm dry

The autoclave is then cooled with liquid nitrogen and transferred to the autoclave 7g SF ₄ in vacuo. The autoclave is then heated for 12h at 140 ° C, cooled and vented. Es 7.5 g of brown liquid are obtained, which solidifies on addition of hexane. Gas chromatographic and mass spectrographic analysis shows that the product is predominantly 2-fluorosulphonyl

tetrafluorbenzoylfluond

with a small addition of 2-fluorosulfonyl-heptafluorotoluene The infrared analysis of the main product shows peaks at 1890 cm ^-1 (-COF) and 1460αιτΓ ¹ (-SO ₂ F)

Example 9

display of

? ₂ 0 (C? (CP ₃ 3G ^ ₂ O) _n CP = CF ₂

The procedures of the above Examples 2,4 and 5 are repeated, wherein instead of 4-fluorosulfonyl-tetrafluorobenzoyl fluoride the 2-fluorosulfonyl-tetrafluorobenzoyl fluoride described in Example 8 is used.

Example 10

Use of an ion exchange membrane in an electrolytic cell.

The 200μπι thick hydrolyzed film described in Example 6 is incorporated into an electrolytic cell containing a titanium net anode coated with RUO2 / T1O2 and a nickel cathode, each arranged as a series of parallel vertical blades, wherein the film between the anode and the cathode A saturated aqueous sodium chloride solution as the electrolyte is constantly supplied to the anode compartment of the cell, and water is constantly supplied to the cathode compartment of the cell. Chlorine and spent solution are constantly removed from the anode compartment and hydrogen and a 20% by weight sodium hydroxide solution become permanent removed from the cathode compartment The cell temperature is maintained at 88 ° C and the electrolysis is carried out at a constant current density of ЗкАітГ ² and a cell voltage of 3.5V

Claims (29)

An ion exchange membrane, characterized in that it contains an organic polymeric material comprising a polymeric chain and at least one chain branching from the chain, wherein the group branching from the chain has a saturated cyclic group and at least one ion exchange group or group which forms a which converts, contains, and wherein the ion exchange group or the group which can be converted into it is linked to the polymeric chain via the cyclic group. An ion exchange membrane according to claim 1, characterized in that it contains an organic polymer material which is a fluoropolymer material. 3. An ion exchange membrane according to claim 2, characterized in that it contains an organic polymer material, wherein the fluoropolymer material is a perfluoropolymer material. 4. An ion exchange membrane according to any one of claims 1 to 3, characterized in that it contains an organic polymer material, wherein the cyclic groups in the groups branching from the chain consist essentially of saturated groups. 5. An ion exchange membrane according to any one of claims 1 to 4, characterized in that it contains an organic polymer material, wherein the organic polymer material contains fixed anionic groups and associated cations. An ion exchange membrane according to claim 5, characterized in that it contains an organic polymer material wherein the fixed anionic groups are sulfo, carboxy and / or phosphono type groups. 7. An ion exchange membrane according to claim 6, characterized in that it contains an organic polymer material, wherein the sulfo group has the structure -SO ₂ X, wherein X is OM and Μ H, alkali metal, ammonium or quaternary ammonium or X is halogen , 8. An ion exchange membrane according to claim 7, characterized in that it contains an organic polymer material, wherein X is F. 9. An ion exchange membrane according to claim 6, characterized in that it contains an organic polymer material, wherein the carboxy group has the structure-COY, wherein Y is OM and M is H, alkali metal, ammonium or quaternary ammonium or Y is halogen or alkoxy. 10. An ion exchange membrane according to claim 9, characterized in that it contains an organic polymer material, wherein Y is alkoxy. - 11. An ion exchange membrane according to any one of claims 1 to 10, characterized in that it contains an organic polymer material, wherein the cyclic group is a carbocyclic group. 12. An ion exchange membrane according to any one of claims 1 to 10, characterized in that it contains an organic polymer material, wherein the cyclic group is a heterocyclic group. 13. An ion exchange membrane according to any one of claims 1 to 12, characterized in that it is an organic polymer material which comprises a polymeric chain of units of the structure -CA ₂ -CA ₂ - and units of structure
-CA ₉ -CA- wherein A is hydrogen, halogen or alkyl, and wherein B is a group containing a saturated cyclic group and an ion exchange group or a group which converts to one, and wherein the ion exchange group or group which is m such convert, is bound via the cyclic group to the polymer chain contains. 14. An ion exchange membrane according to claim 13, characterized in that it is an organic polymer material, wonn the group B, the structure (DSO ₂ ). where D and E are single bonds or divalent groups, η is an integer of at least 1 and X is QM where M is H, alkali metal, ammonium or quaternary ammonium or X is halogen. 15. An ion exchange membrane according to claim 13, characterized in that it is an organic polymer material, wherein the group B is the structure (DGOY) _n where D and E are monovalent or divalent groups, η is an integer of at least 1 and Y is O, wherein M is H, alkali metal, ammonium or quaternary ammonium or Y is halogen, cyano or alkoxy. 16. An ion exchange membrane according to claim 14 or 15, characterized in that it contains an organic polymer material, wherein the cyclic group is a perfluorinated group. 17. An ion exchange membrane according to claim 14 or 16, characterized in that it is an organic polymer material, wherein the group B has one of the following structures DSO ₂ Z contains. 18. An ion exchange membrane according to claim 17, characterized in that it contains an organic polymer material, wherein the group D has the structure CFa. 19. An ion exchange membrane according to claim 15 or 16, characterized in that it is an organic polymer material, wherein the group B has one of the following structures DCOY DCOY DCOY contains. An ion exchange membrane according to claim 19, characterized in that it contains an organic polymer material, wherein D has the structure -CF ^. An ion exchange membrane according to any one of claims 17 to 20, characterized in that it comprises an organic polymer material, wherein E has the structure (0CF 2 -CF R f) _n -, where N is an integer and R f is F or a perfluoroalkyl group, or the structure - (OCFz-CFRf) nO (CF2) m, wherein η and m are zero or an integer and Rf is F or a perfluoroalkyl group. 22. An ion exchange membrane according to any one of claims 13 to 21, characterized in that it contains an organic polymer material wherein A is F. 23. An ion exchange membrane according to any one of claims 1 to 22, characterized in that it contains an organic polymer material which contains units obtained by polymerization of a monomer of the structure cp ₂ »cp- (oop ₂ -cp (CP SO ₂ X wherein the-SOaX group may be in the 2-, 3- or 4-position wherein the cyclic group is fully fluorinated and saturated and wherein η is zero or an integer from 1 to 3. 24. An ion exchange membrane according to any one of claims 1 to 23, characterized in that it contains an organic polymer material which contains units obtained by polymerization of a monomer having the structure CP ₂ -O-CP = CP ₂ CP ₂ = CP- (OCP ₂ -CPCCP ₃ ) J _n - so ₂ x wherein η is zero or an integer of 1 to 3 and wherein the cyclic group is fully fluorinated and saturated. 25. An ion exchange membrane according to claim 23 or 24, characterized in that it is an organic polymer material, wherein the organic polymer material is produced by copolymerization of the monomer with tetrafluoroethylene. An ion exchange membrane according to any one of claims 1 to 25, characterized in that it contains an organic polymer material containing from 0.4 to 4.0 milh equivalents of ion exchange groups per gram of organic polymer material. 27. An ion exchange membrane according to any one of claims 1 to 26, characterized in that it consists of a substantially hydraulically impermeable film or film. 28. An ion exchange membrane according to claim 27, characterized in that the film or film has a thickness of 50 to 500 μιτι. 29. An ion exchange membrane according to claim 27 or 28, characterized in that it contains 0.4 to 4.0 milliequivalents of ion exchange groups per gram of membrane. 30. Use of an ion exchange membrane according to any one of claims 1 to 29 in an electrolytic cell, characterized in that it comprises at least one anode and at least one cathode and an ion exchange membrane which separates an adjacent anode and cathode, whereby the electrolytic cell in separate anode and cathode rooms is shared. 31. Use according to claim 30, characterized in that it is used in a process for the electrolysis of aqueous alkali metal chloride solution.