DE2614058C2 - Cation exchange membrane - Google Patents

Description

Diameters that are present in a heterogeneous membrane do not readily correlate with the inorganic one Ion exchanger are filled.

Membranes made of a fluorinated resin are particularly resistant to chlorine and strong acids, ι As fluorinated resins, all those can be used by introducing sulfonic Groups, carboxylic groups and / or phenolic groups in a polymer or a Copolymer of essentially tetrafluoroethylene, in Hexafluoropropylene, trifluorochloroethylene, trifluoroethylene, Fluorovinylidene, a, / ?, 0-trifluorostyrene and perfluorovinyl ether are made. Particularly preferred within this group is a tetrafluorosulfonic acid membrane, under the trade name »NAFION« is put into circulation by E. I. Du Pont de Nemours & Co. Inc. This membrane consists of a fluorinated resin with terminal sulfonic acid groups, which contains the following structural units:

R.

C-CFR ₂ - and - {CXZ— CFR ₃ J-

SO3H

In this formula, R represents a structural element of the shape

- _t O - CR ₄ R ₅ -CR ₆ R ₇ J ^ -

Ri to R7 each represent a tetrafluoroalkyl group with 1 to 10 fluorine or carbon atoms, Y stands for a perfluoroalkylene group with 1 to 10 carbon atoms, and in the case of the index letters m runs from 0 to 3, π from 0 to 1 and ρ likewise from 0 to I. X also represents a fluorine, chlorine, hydrogen or trifluoromethyl radical and Z represents the group CF ₃ (CF ₂ ), where q runs from 0 to 5.

Instead of the above-mentioned polymers or copolymers, those fluorinated resins are also very suitable, in which sulfonic acid groups are introduced into a benzene ring or which are produced in that monomeric styrene or monomeric acrylic acid is subjected to a graft polymerization and then through Sulfonation or hydrolysis ion exchange groups have been introduced into the graft polymer. Farther a sulfonate of tetrafluorostyrene gives a good one particularly in terms of corrosion resistance Merabran. It can be used in particular if a membrane with only low resistance to chlorine is on the anode side is used to form a neutral filter between the anode and that during operation another membrane, which allows the passage of brine and keeps the chlorine away from that other membrane.

The inorganic ion exchanger used in the process according to the invention is a water-insoluble one Hydroxide, hydrated oxide or polybasic salt of zirconium, titanium, tin (IV), cerium, thor. Lanthanum, manganese (II), silicon, niobium, tantalum, antimony (V), molybdenum (Vl), antimony (III), bismuth, indium, Manganese (III), iron (III), gallium, aluminum, cadmium, zinc, magnesium, beryllium and / or hafnium.

It is known that the aforementioned cations are both water-insoluble and water-insoluble hydroxides can form hydrated oxides or polybasic salts. Among them are the metal ions with a valence of four or more particularly suitable because they contain hydrated oxides with very large Ion exhaustion capacity. According to another selection criterion, those are cations particularly suitable whose hydroxides, hydrated oxides or polybasic salts have a cation exchange capacity because they have a low electrical resistance. Furthermore, according to a third selection criterion, the cations with a high Alkali resistance particularly suitable. Taking these various selection criteria into account a preference for the use of zircon, titanium, cerium, thor, niobium, tantalum, and antimony Hafnium as cations. Mixtures of the different cations can also be used for the inorganic ion exchanger can be used. As an acid residue for the formation of the water-insoluble polybasic salts phosphoric acid groups, molybdic acid groups and tungstic acid groups have proven themselves.

In order to avoid the effects of the introduction of the water-insoluble inorganic ion exchanger into the polymer Material achievable improvements in the cation selectivity of the membrane for practical use bring, it is necessary that at least 0.01 wt .-% of inorganic ion exchanger, based on the Weight of the original polymeric material incorporated into the membrane. If the amount of inorganic ion exchanger is below 0.01% by weight, nothing more important in practice occurs Effect more on. The upper limit for the content of inorganic ion exchanger in the membrane is at 30% by weight contents. Above 30% by weight lead to membranes with an electrical resistance that is too high, which are practically unusable. Within the range from 0.01 to 30% by weight, the Water-insoluble hydroxides, hydrate oxides or polybasic salts of the metals mentioned do not necessarily be present in stoichiometric composition. In the case of e.g. B. of polybasic salts these can be connected to the periphery of a frame structure made of a metal oxide polymer. in the Otherwise, there is no restriction in the invention with regard to the proportion of the metal in with respect to the hydroxyl groups, acid residues, etc.

The cation exchange membrane produced according to the invention shows excellent results in terms of both the swelling characteristic and with regard to the effect as an ion exchanger. The areas swollen by water within the Membrane are largely or partially filled by the inorganic ion exchanger that in turn, is not swellable by water. This is the cause of the reduced water content of the Membrane, the increased ion exchange capacity of the membrane and the increased density of those in the membrane fixed ions, i.e. for improved cation selectivity. As will be explained in more detail below, for example, the content of the membrane increases 0.32% by weight of titanium hydroxide is the density of the ions fixed in the membrane (measured in meg / g HO) about 16% i: n. When 2.3% by weight of cerium hydroxide is introduced into the membrane, there is an increase

the density of the ions fixed in the membrane by more than 10%. If, in the case of the electrolysis of a brine, a polybasic metal salt such as zirconium phosphate in the Membrane is introduced, the increase in the density of ions fixed in the membrane results in the extreme high current efficiency of 95% or more, under conditions in which the concentration of caustic soda in the cathode chamber is 20%.

If the polymeric membrane material has high strength and durability, the metal ions of the inorganic ion exchanger introduced into the membrane according to the present invention are not easily washed out even under extreme conditions. For example, the zirconium of a zirconium phosphate introduced into a high-strength cation exchange membrane (NAFION 110) showed no noticeable decrease in concentration when measured with the X-ray fluorescence method when the membrane was in a saturated aqueous chlorine solution at 80 ° C or an aqueous solution of hydrochloric acid for 600 hours or more acid (effective chlorine concentration is about 5%) was allowed to stand at 100 ⁰ C, or an aqueous Lösutig 40% caustic at 80 ° C.

The inorganic ion exchanger is subsequently added to the surface or to the interior of the Cation exchange membrane introduced as it, if in the manufacture of the membrane, the inorganic Ion exchanger mixed into the starting resin material is difficult to obtain a uniform one To achieve distribution of the inorganic component in the raw resin material. But there it is impossible to use the inorganic component as such, i.e. H. in their solid, water-insoluble state, in which Introduce membrane, in this case, either from a solution of a soluble form of the inorganic Ion exchanger or of a dissolved or liquid metal compound that is the metal of the ion exchanger contains, assumed. The solution or liquid is thereby on the surface of the already finished membrane adsorbed or on the surface or gffs. also into the interior of the membrane absorbed and then solidified or transformed into the ion exchanger by a subsequent reaction.

For example, a solution containing the metal ions of the ion exchanger can be used, followed by treatment of the membrane with a hydroxyl ion or acid group containing solution in the membrane or on its surface, the final ion exchanger is formed will. Likewise, the membrane can also initially with that containing the hydroxyl ions or acid groups Treated solution and then reacted with a solution containing the metal ions of the ion exchanger will. So it is B. possible, the cation exchange membrane first in an aqueous solution of a Exchange zirconium salt such as ZrO (NO3) 2, whereby Zirconium ions are adsorbed on the surface of the membrane. If then the membrane is in a aqueous caustic soda solution or a solution of a water-soluble polybasic acid is immersed, A gel forms on the surface of the membrane, which is made from zirconium hydroxide or the zirconium salt of the concerned polybasic acid. If the order of this immersion is reversed, so first the solution of caustic soda or polybasic acid and then the solution of the zirconium salt are used dps gel is formed in the same way.

In all cases of using a solution, c.as Solvents do not necessarily have to be water; rather, non-aqueous solvents may also be suitable. When using naturally liquid metal compounds such as. B. Tetrabutyltitanium is an additional one > Solvents generally not necessary.

It is also possible to first form a water-insoluble one in or on the membrane Forming the salt and then converting it into the final form of the inorganic ion exchanger

to convert into. So z. B. initially a hydroxide or a hydrated oxide of the metal in or on the Membrane are formed and this can then be further reacted to form phosphate.

The amount of the inorganic ion exchanger in

υ or on the membrane can be controlled by the Selection of the concentration of the solution applied and by the method as well as the duration of the Application of this solution. For example, if the inorganic ion exchanger only applies to one

Λ! Surface of the membrane is applied and the Treatment is controlled so that the ion exchanger is only in the surface adjacent to the treated When the surface layer forms, there can be an excessive increase in the electrical resistance of the membrane

2> suppress. This special treatment may conveniently be carried out v / ground that a surface de \ membrane with a solution containing the metal ions of the ion exchanger is coated or soaked with this solution, filter paper or

m fiber fabric is placed on the surface and contact is maintained until the metal ions have penetrated the surface layer of the membrane to the desired depth. After that then the metal ions with hydroxyl groups

j, or acid groups implemented. Of course, the order in which they are used is reversed the solutions containing the metal ions and the solutions containing the hydroxyl groups or acid groups are possible.

As an example of a superficial coating or

4 (i a more or less deep impregnation of the Membrane with a liquid compound should be mentioned the use of liquid metal compounds such as Titanium tetrachloride or antinion pentachloride or aqueous Solutions to these compounds. Also the use of tetrabutyltitanium or similar compounds belongs to this group.

The gel of a hydroxide formed in or on the membrane in the manner described above, hydrated oxide or polybasic salt of the

ίο concerned metal ions is still dehydrated. in the In general, the higher the dewatering temperature, the higher the corrosion resistance of the membrane and their resistance to mechanical shocks increases. A number of those up for debate

However, icing metal compounds tend to have a reduced ion exchange capacity if the dewatering takes place at too high temperatures. The dewatering temperature is usually between 30 and 200 ° C. Depending on the dewatering temperature, the electrical resistance and the current yield of the final be influenced membrane. for example, was the electrolysis of a brine using a ^r cation exchange membrane comprising a non after its formation

μ dried zirconium phosphate, the cell voltage at 3.65 V, while under otherwise identical conditions, but with previous complete drying of the membrane at! 10 ⁰ C the cell voltage

4.0 V, instig. Generally lead a previous one Dewatering or drying of the membrane compared to one that has remained untreated in this respect Membrane to an enlarged /.ellenspanniirig. but also to a greatly increased ion selectivity and thus / u a better stiomaiisbcutc. By doing The aforementioned example was owned by the nichl-bchandelte Membrane has a current output of 8%. while the previously dehydrated membrane had the significantly better slromaiisbute of 96%. In the sense of the Invention is therefore provided that after the introduction of dos inorganic ion exchanger in cliο Membrane a dehydration treatment and its temperature depending on the intended use the membrane is selected and adjusted.

The invention is not limited to single-layer membranes, but is equally applicable in the case of membranes made up of two layers with

pa / ies are composed.

When the membrane of the invention in a electrolytic cell is installed, sometimes, for example in the electrolysis of alkali halides, as a result of the ablation of swelling processes Expansion or, if these processes are reversed, a contraction of the membrane occurs, and this can have an influence on the cell voltage but damage the oiler Membrane. This circle becomes the membrane preferably in one that is as swollen as possible State built into the cell. Usually becomes too for this purpose the membrane either constantly in a sufficiently swollen state before installation held or dipped once in hot or boiling water.

In the following, the invention is presented in numerical terms Execution 'examples and with reference to the explained in more detail in the attached tables.

example 1

A membrane .ms NAEION '10 μm with a thickness of about 250 μm was dried ¹ at 110 ° C. for one hour. The membrane was then placed at room temperature for two levels in a 10 '' aqueous solution. / -! ■ :,> nv chloride and then thirty minutes: ": \ j: with an 85 ^l! -'Iee aqueous solution of phosphoric acid. After sufficient washing with water, the membrane finally became a hour Jang be; 0 C dried oils amount Jos mi into the membrane introduced Zirkonphosphatv was 1.2 wt - ¹ · ... based on the weight of the original membrane after T ^r ocknung!...

[3 wa-sergehah. the cation exchange capacity and the density of ions fixed in the membrane ir, the Taoeiie Ϊ stated. For comparison, the Ta-elie 'also the corresponding values for a containing no zinc phosphate, but otherwise the same membrane made of NAFION 110 is specified.

The water content given in Table 1 represents the. percentage by weight! of the water contained in the membrane after the membrane has been immersed for one hour in water at 15 ^: C. The water content is significantly lower for the membrane treated according to the invention. The density of the ions fixed in the membrane is correspondingly higher.

Silk membranes were immersed after drying at "0" C for two hours in water at room temperature, and electrolysis was then carried out with the aid of these membranes in each case under the conditions specified in Table 2. The results of this electrolysis are shown in Table i .

The 'Label J shows that the increased density of the ions fixed in the membrane leads to excellent cation selectivity and a increased current yield allowed.

Example c

A membrane made of ΝΛΠΟΝ 110 with a thickness of about 250 (im was cut to a size of about fxi em and then dried for eighteen hours at IOC. The membrane was then immersed in an aqueous solution of 50 g heated to 80 ° C. for one hour Zirconyl nitrate immersed in 100 cm of ¹ N hydrochloric acid, and after the membrane was taken out of this solution, its surface was very quickly wiped with paper, and then the

u 1 -: - ci " \ : ..";-> nn /: - M - / - MJ ι ^

IVIL [IIIJIiUI CMI *. .1ItIIIUl. lillip III LIIIV. Jl / il'lgL l ^ ilWII-ΙΛ /

solution of 8OC immersed. Eventually the Membrane washed sufficiently with ion-exchanged water and then at IIO C for eighteen hours dried.

The cation exchange capacity of the membrane treated in this way was 1.00 megg of dry membrane material. An identical membrane, but not treated according to the invention, had a cation exchange capacity "on 0.97 meg / g. Thus, the treatment according to the invention led to an increase in the Cation exchange capacity.

During the electrolysis of a salt oil with the help of this The values given in Table i were obtained for both membranes. The electrolysis was done carried out under the conditions of Table 2. Again, the superiority of the to recognize membrane according to the invention.

Examples 3 to 5

Three membranes made of NAFlON ilO with a thickness of about 250 µm were measured for one hour at 110 (. ' dried. The hydroxides or polybasic salts were then given in Table 1 Metal ions introduced into the membranes concerned.

From the corresponding values in table i it follows that in comparison to a rich invention'-L'emäß treated, but otherwise the same membrane made of NAI ION UO as well as bein; Example ! the water content diminished and the third in the membrane Ion is enlarged.

Example! ti

A membrane from NAFION '. 10 having a thickness of about 250 m was immersed in a 80 to 9Q ten ^minutes: C ir heated aqueous solution of 50 g of zirconyl nitrate ^00cm!:! N-hydrochloric acid immersed. After removing the surface of the membrane was sufficiently wiped dry, and then the membrane was twenty minutes in a -'oige 2O ° NaOH aqueous solution 'on! Immersed 00 ⁷ C. Gel formation was hardly observed in the aqueous NaOH solution. After the membrane was taken out of the NaOH solution and washed with water. it was immediately for ten minutes in a 120 C ^r on heated 8O ° strength aqueous phosphoric acid solution immersed. The membrane became whitish, whereas the formation of a gel from zirconium □ hosoha: in the aqueous phosphoric acid solution

flour was observed at all. The phosphoric acid could therefore be reused. The membrane was washed again with water and dried for one hour at 110.degree. C. and then for one day at Stored at room temperature. The concentration of the zirconium phosphate introduced into the membrane in this way and the zirconium and phosphorus were measured by the X-ray fluorescence method. The knife- ·,: Results are given in Table 4.

With the membrane produced in this way, and / was with an effective surface area of 25 cm, a Elcktrolysiert brine. The electrolysis conditions are shown in Table 2, while the results obtained appear in Table 5.

H e i s ρ i e I 7

[• A membrane from NAIK) N lit) of the silicon acid type and with a thickness of about 250 μιΐι was dried for one hour at 100 (and then for fifteen hours at room temperature in a JO'Voiue aqueous solution of ZrO (NOi); 2II; (). The membrane was then immersed in a K ¹ J ¹¹ ZiHgC aqueous phosphoric acid solution, then washed with water and finally dried for one hour at 100 (. This resulted in a membrane with a content ν ·· : ι>. ()% by weight of zirconium phosphate, based on the weight of the original membrane. Furthermore, a corresponding membrane made of NAfK) N 110 of the sodium sulfonate type was treated in the same way. The amount of zirconium phosphate introduced into the membrane was 7.4 Wt .- "/ n. Based on ■ nif the weight acc original membrane.

Both the membrane from the sulfonic acid type and the sodium sulfonate-type membrane were on finally treated again in the manner described above. The salary increased Zirconium phosphate in the membranes to 11.2% by weight "Zo or I 3.8% by weight" / "in each case based on the Weight of the original membrane.

This was followed by a third treatment to introduce more zirconium phosphate into the membranes. In the case of the sulfonic acid type membrane this treatment was again the same as the treatment mentioned above and there was an increase in Zirconium phosphate content to 17.3% by weight. The membrane from the sodium sulfonate-Tsp was in the third Treatment level, on the other hand, is treated a little differently. She was after the end of the second stage of treatment Immersed in boiling water for one hour at 100 C, then in one for fifteen hours 10% aqueous solution of ZrO (NOi). '■ 2 H: O given, then immersed for one hour in an 85% aqueous phosphoric acid solution, finally washed with water and then dried at 100 ° C. for one hour. As a result, the salary increased Zirconium phosphate in this membrane to 23.5 wt .-%. again based on the weight of the original Membrane.

From this example it can be seen that the amount of in the zirconium phosphate introduced into the membrane can be varied by the treatment conditions.

Example 8

Flat glass plates and were placed inside a stainless steel polymerization vessel Teflon nets (the latter as reinforcement elements) arranged in a sandwich-like form. Then became είπε Monomer mixture consisting of 65 parts by weight of styrene, 35 parts by weight of divinylbenzene and I. Part by weight of benzoil peroxide (as a polymerization initiator) introduced between the glass plates. The polymerization was done in a nitrogen atmosphere at 60 C and lasted sixteen hours. Afterward the mass within the polymerization vessel was adjusted to a temperature of 80 "C and three Maintained at this temperature for hours. Then a membrane made of styrene-divinylbenzene could be made from the Be removed from the vessel. This membrane was made by soaking in ethylene dichloride for three hours Swollen at room temperature and then immersed in 98% concentrated sulfuric acid for sixty hours immersed at 40'C. This resulted in sulfonation; H. a cation exchange membrane was formed. The density of ions fixed in the animal membrane was ! .2 meg / g H> O at bO'C.

This membrane was then immersed in a boiling 10% aqueous solution for thirty minutes Solution of sodium molybdate immersed and then held in a 100 ° C "for thirty minutes saturated solution of SnCl> 1 IjC) in 1N hydrochloric acid ran over ;. In this way tin molybdate became animal Membrane formed, in an amount of 0>) wt.%. based on the weight of the original animal Membrane. It was observed that a slightly yellowish mass of tin molybdate within the Membrane was depressed. The density of the ions fixed in the membrane was 3.6 meg'g ILO at hO'C and was thus higher than the corresponding value for the untreated membrane.

Examples 9 and 10

A NATION 340 membrane was assumed. This is a sodium sulfonate type cation exchange membrane. in which two membranes of the type EW-10000 and EW-1500 are laminated to one another with intermediate nets made of ethylene tetrafluoride resin and rayon. This membrane was immersed in a 50% aqueous solution of zirconyl chloride at room temperature for four hours. Thereafter, its surface was wiped dry with Eilterp: .pier, and then the membrane was transferred to an 85% aqueous phosphoric acid solution. In this case formed in the membrane of zirconium phosphate in an amount of 3.2 wt ⁰ Zo. based on the weight of the original membrane.

Two samples of the membrane treated in this way were removed from the phosphoric acid solution after thirty minutes removed, washed sufficiently with water and then for one hour at 110 ° C (Example 9) or at 75 ° C. (Example 10). Both samples dried in this way were then dried for two days stored in water at room temperature for a long time and then placed in a for electrolysis Electrolytic cell introduced. In each case, the side with the membrane of the EW-ILOO type faced the anode of the Cell.

The electrolysis was carried out under the conditions given in Table 2 and with the example! I same Conditions carried out, the electrolysis results are shown in Table 5. For comparison, was also used another membrane made of NAFION 390 was measured, which was treated in the same way as the membrane according to Example 9, but contained no zirconium phosphate.

The NAFION 390 type membrane naturally has a relatively high current yield because it is a of two ion exchange membranes with different

Il

chert ion exchange capacity en compound Membrane is. If zirconium phosphate is also introduced into this membrane, the cell voltage increases although slightly, but at the same time there is also an extraordinarily strong increase in the current bulge. which is substantially above the current yield of the membrane not treated according to the invention.

The reasons that a membrane of the type NAFION 390, ie ^H of two interconnected lonenaustauschrnembranen with varying ion exchange capacity is compared with a single-layer membrane has a better current efficiency results are not yet clarified. It can, however, be assumed that the membrane of the type F'VV-1500 shows only a relatively low tendency to build up in water and thus has a higher density of ions fixed in the membrane in the electrolysis. which means a correspondingly large ion exchange capacity. This can act as a barrier through which the diffusion of hydroxyl groups from the cathode is prevented - / ity of the membrane EWI 100 have their own special value in that the swelling tendency of this membrane in water is suppressed by the fact that the membrane FW-I 500 is used. This can lead to an increase in the density of the ions fixed in the FW-I 100 membrane in the vicinity of the interfaces between the two membranes.

If an inorganic ion exchanger is now introduced into this membrane, it will likely be Adhere more strongly in those areas of the membrane in which there is already an increased density of the membrane in the membrane fixed ions is present. As a result, this ion density is additionally increased, which has the consequence. that the characteristic features of the membrane are further improved and become extremely high Cation selectivity adjusts.

Example Il

A layer of filter paper previously immersed in a 10% aqueous solution of zirconyl chloride was placed on the side of a two-layer membrane of the NAFION J90 type (sodium sulfonate type) provided with the EW-1500 membrane and left there for fifteen minutes at room temperature. Thereafter, the filter paper layer has been removed and instead placed another layer of filter paper on the above-treated side of the membrane, which was getriinkt with a 85 ⁿ / o aqueous solution of phosphoric acid. In this way, zirconium phosphate was only introduced on the EW-1500 side of the NAFION 390 type membrane.

After washing sufficiently with water, the membrane was dried at 110 ° C. for one hour and then stored for one hour in water at 15 "C. The The amount of zirconium phosphate introduced was 0.23% by weight based on the weight of the original Membrane.

The membrane treated in this way was similar to Examples 9 and 10 in an electrolytic cell built in, with the EVV-1 100 ropes back to the anode lay down The electrolysis was carried out under the conditions given in Table 2, again with the conditions in Examples I and 4 and 10 match. The results of the electrolysis show Table 3, and again there is the very good one Recognize cation selectivity of the membrane.

Example 12

A sulfonic-type NAFION 315 membrane (a bonded membrane composed of a layer of EW-1100 and a layer of EW-1500 with a mesh of ethylene tetrafluoride resin in between) was immersed in an 85% aqueous phosphoric acid solution for two hours dipped of 120 ⁰ C and then immersed in an IO ° / o aqueous solution of zirconyl chloride of 100 after sufficient wiping the membrane surface, a ten minute "optionally C. after sufficiently washing with water, the membrane was then for two hours at 110" dried C . The amount of the zirconium phosphate thus introduced into the membrane was about 3% by weight. based on the weight of the original membrane.

This membrane was again used for electrolysis, with the EW1 100 side again facing the anode. The electrolysis conditions are shown in Table 2 and are similar to those of Example 1 and Examples 9 to II, however, that the cell temperature was, except 70 C ^7. The results of the electrolysis are summarized in Table 3. For comparison, the data are again given for the underlying membrane made of NAFION 315 without a content of zirconium phosphate.

Table 1

Properties of the membranes

Inorganic ion exchanger
Metal ion anion

membrane Ion exchange Density of lot Water content capacity fixed ions (Wt .- \) at 15 C (meg / g (meg / g HiO) (Wt .-%) dry resin) 1.02 9.7 1.2 10.5 0.98 7.8 - 12.6 1.00 0.97

example 1
Comparison 1

Example 2
Comparison 2

Zircon

Zircon

phosphoric acid

OH

¹ ! 'ΓΙμ'Ι / ιι .J

13th

Mchillinn

Example 3 Example 4 Example 5 Comparison 3

Titanium Ccr (IV) Ccr (IV)

aniline

L Iu I

Oll Oll Molvbdänsiiurc

My in.in Ion exchange Density of \ 1cnuc W.isscrech.ill K.ipa / il.il Imcilcn Ionon K icw ι lic ι l <( (ηιομ'μ (im-μ / μ If- (I) ((ic «. · I dry 11, π / I 9.1 0.32 11.4 11.7 2.3 ⁽ ). (ι ⁽ '.8 1.8 10.7

7.S

Table 2

I! I c kl ro Iy se conditions

Hcispicle I sewie ¹ I 1? Example : UcispiL-l (■ anode Titan-R lithe ni Li ni-Ox id (iraphil ritan-rutheniiim - () \! i cathode Net / stainless steel stole stole (8 Tyler-Ma s clic η) Absland A node cathode 5 mm 10 mm Kl mm Brine con / enlralion 26 ",, 2 (i ".. 2 (V- / ellenlemperaUir 80 ((70 C for example 12) 50 (' 50 55 c Current density 20 A / dm " 2!) Λ / dm ' 2 (1 \ / dm '

Table 3 N.iOII-Kiin / enlr.ilion in
the cathode chamber / rush ·.
l \ 1 p.iiiniiiii: Sir.im
II r. electrolysis results 21.2%
18.0 ", 3.65 "6
"(I. 4.2 N
4.1 N 3.S
3.S SI example 1
Comparison I. 6 N. 4.0
3rd p (■ " Example 2
Comparison 2 22.6- ^ - 04.0 Example 6
Comparison 6 20.0%
20 1% S 4 Example 11 Example 12
Comparison 12

Tabel

Zirconium phosphate content of the membrane according to Example 6

Weight Zr X 100 G ew ot P. ·: Loo Gcuich ; 7-PO, j I 'f.' Zr .l-.orhTiini- Total*) Ges ami " I. Gesa rr.i "i : PO.

2.30 0.16:. ^{7 (} 5th

*) Total = total weight of the membrane.

4.69

Table 5

Influence of dryness teniperalur on the heat lysis results

Drying NaOII-Knn / eiuruliiin / rushing slrnmaushule

temperalLir in the Kalhudenkanimer tension (";,)

C- (V)

Example 9 HO 24.0 ",;,

Example 10 75 22.3%

Comparison 9 f H) 110 21.7%

4.0 95.3 3.9 93.2 3.60 87.8

Claims (1)

Claim: Process for the production of cation exchange membranes from a fluorine-containing, corrosion-resistant Ion exchange resin which contains sulfonic acid, carboxyl or phenol groups, characterized in that one of the ion exchange resin produced membrane initially with a liquid or in an in Solvent-dissolved compound forming the water-insoluble inorganic ion exchanger, which as cation zircon, titanium, tin (IV), cerium, thor, lanthanum, manganese (II), silicon, niobium, tantalum, Antimony (V), molybdenum (Vl), antimony (III), bismuth, indium, manganese (III), iron (III), gallium, aluminum, Contains cadmium, zinc, magnesium, berryllium and / or hafnium, is treated and then in a solution that converts the cation into a hydroxide, hydrated oxide, or polybasic salt as inorganic ion exchanger is converted, immersed and then dried, the Amount of the inorganic ion exchanger introduced into the membrane 0.01 to 30% by weight, based on the weight of the original membrane. Ion exchange membranes consist of or contain a polymeric ion exchange resin such. You can in electrodialysis or electrolysis in particular of aqueous solutions or can be used in numerous other appropriate cases. In more recent times the industrial The importance of ion exchange membranes has increased steadily. For example, ion exchange membranes are used with cation selectivity to an increasing extent in the production of gaseous halogen, gaseous hydrogen and caustic alkali by electrolysis of aqueous alkali halide solutions used. As these products are important chemicals that are required in large quantities by industry represent, there is consequently an increasing need for ion exchange membranes in practice greatest possible performance. For the performance of an ion exchange membrane, it is crucial that it also under difficult operating conditions, especially in operating modes with low energy consumption, is sufficiently resistant and durable. To reduce the energy consumption of an electrolysis cell, it is necessary to lower the cell voltage and increase the current yield. If now for example in the electrolysis of an aqueous alkali metal halide solution with increased current efficiency is carried out, a cation exchange membrane with the highest possible cation selectivity must be used will. In general, the ion selectivity of an ion exchange membrane depends on the density of the Membrane fixed counterions, d. H. the relative amount of fixed counterions, based on the Water content of the membrane. Thus there is an increase in the cation selectivity in that the The density of the anions fixed in the membrane is increased. However, if for this purpose simply more Anions are introduced into the membrane, so does the hydrophilic nature of the membrane accordingly too, so that the membrane absorbs a correspondingly increased amount of water during operation and swells up more. But since this again reduces the density of the anions fixed in the membrane, it is this measure makes it impossible to effectively increase the density of the ions fixed in the membrane. In order to suppress the swelling tendency of the membrane, it has already been proposed that the membrane forming polymeric material to a high degree or the membrane from two superimposed To make layers. However, these countermeasures are compensated for by a decrease in the mechanical strength and an increase in the electrical resistance of the membrane, so that in the The result is no improvement in the overall performance of the membrane. With the invention, the performance of a cation exchange membrane is to be improved and In particular, a cation exchange membrane can be created, which at optimal mechanical and electrical values has excellent cation selectivity. This aim is achieved according to the invention achieved by a method according to claim. The invention is based on the consistent use of the knowledge that the water content of the Membrane, which is decisive for the density of the anions fixed in the membrane, by introduction a third substance can be reduced into the membrane. If this third substance is an inorganic one Is ion exchanger, the areas of the membrane swollen in the water can be more or less are less filled with these inorganic ion exchangers, the ion exchange groups of the resin with the inorganic ion exchanger. This leads to an increase in Number of anions fixed in the membrane without changing the water content of the membrane accordingly increased, d. H. the result is an effective increase in the density of those fixed in the membrane Anions and thus a considerable improvement in cation selectivity. The mechanical strength the membrane is not affected, while the electrical resistance of the membrane is lower. The membrane thus has an optimal suitability in particular which cannot be achieved with conventional means for modes of operation with high current yield. When the cation exchange membrane produced according to the invention is used in the electrolysis of alkali halides is used, a highly concentrated alkali metal hydroxide solution can be obtained with a high current efficiency will. However, the applicability of the membrane produced according to the invention is not in this case limited. Since it shows its excellent cation selectivity even in dilute solutions, it can can also be used in all other electrolysis and electrodialysis processes, including those involved in the production of drinking water from seawater, the concentration of dilute solutions, aim at the treatment of waste liquids or the like. A homogeneous membrane is assumed for the method according to the invention. A heterogeneous one Membrane, d. Iv a mixed membrane made of an ion exchange resin. and a nonionic resin is inconvenient because it is inevitably low . Current efficiency and low ion selectivity shows. Furthermore, the pores can also become larger