DD150764A1 - ELECTRODE FOR ELECTROCHEMICAL PROCESSES AND METHOD OF MANUFACTURE - Google Patents

Abstract

The object of the invention is the perfection of graphite-based electrodes for increasing the service life at the current densities used in industry. The electrode has a base of graphite in the pores of which metals or metal compounds which have electrocatalytic properties and are in electrical contact with graphite and an electrochemically inert organic substance which is insoluble in the electrolyte and which has a melting point and / or a temperature of transition into the electrolyte gaseous state, which is or are higher than the temperature of the electrode in the electrolysis. The method of making an electrode is to introduce into the pores of the graphite base first metals or metal compounds having electrocatalytic properties, and then an electrochemically inert organic substance insoluble in the electrolyte, which has a melting point and / or a transition temperature has the gaseous state, which is or are higher than the temperature of the electrode in the electrolysis.

Description

57,371 / 17

Electrode for electrochemical processes and method of manufacture

Field of application of the invention

The present invention relates to electrochemical processes, in particular to an electrode for these processes.

Characteristics of the known technical solutions

At present, in the electrochemical production of chlorine with solid and liquid cathodes and in the production of chlorates, ifypochlorite and other products, graphite anodes are used, the disadvantages of which are short life and the formation of a larger amount of sludge during electrolysis.

During the last decade, electrodes having a metallic base to which a thin coating of electrocatalytic properties is applied are becoming more widely used.

For example, electrodes are known which contain a current-carrying substrate made of titanium, niobium, tantalum, zirconium and an applied coating which is resistant to the electrolyte and the electrolysis products and which consists of a mixture of one or more oxides of the film-forming metals aluminum, tantalum, titanium, Zirconium, niobium, bismuth and tungsten with one or more metals: palladium, platinum, rhodium, iridium, ruthenium, osmium, gold, silver, iron, nickel, chromium, lead, copper, manganese and oxides of these metals, mtrides, carbides, silicates

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fiden as well as their mixtures exists (see USSR certificate of origin Mr. 3 ^ 9 923).

These electrodes have significant advantages over graphite electrodes. The main advantages of the oxide-metal electrodes compared to the graphite electrodes are:

a) significantly longer life of the electrodes;

b) stable dimensions of the electrodes precluding growth of voltage in the time of their use during solid cathode electrolysis and the need to control the position of electrodes to maintain voltage constant in electrolysers with mercury cathodes;

c) lack of mud polluting the diaphragm.

Despite the advantages mentioned, however, oxide-metal anodes are not widely used, especially as a result of their higher costs compared to graphite electrodes.

An essential part of the oxide-metal anodes is their high sensitivity to short circuits, which limit their broad application in electrolysers with mercury-type cathodes. Therefore, work continues to be done to significantly improve the operating characteristics of the graphite electrodes.

Graphite electrodes are known which are impregnated with various electrochemically inert organic substances, for example with polymerization products of oils (CA-PS Kr. 602 053), polyester resin (CS-PS Hr. 95 463), allyl resins (JA-PS class 13/7 / D 131, 48-15149), polymerization product of tall oil varnish (SU-Kaiser, supra 167 832).

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220562 "3-

Practically, with the use of graphite electrodes impregnated with electrochemically inert organic substances as the anodes of the chloroelectrolyzers, the resistance of the anode to the undoped graphite anodes does not increase more than one-and-a-half times.

A disadvantage of these anodes is the limitation of the permissible operating current densities (for example not more than 1.5 kA / m in fixed cathode chlorine and chlorine generation)

not more than 8 to 9 kA / m in the generation of chlorine with mercury cathode), At higher current densities accelerated destruction of the anode is possible due to the exceeding of the critical source potential. The cause of the limitation of the operating current density is the higher potential of the anode after its impregnation with the inert organic substances Pur electrodes, which are impregnated with complete closure of the pores, which is particularly expedient with regard to the reduction of internal wear, is the permissible current density significantly lower than the current density used in current electrolysers,

Also known are electrodes based on graphite in which the porous graphite base is on the surface. or in the pores contains metals or metal compounds which have electrocatalytic properties. For example, an electrode is known which comprises a coated graphite power supply base made of a mixture of one or more oxides of the film-forming metals aluminum, titanium, tantalum, zirconium, niobium, bismuth and tungsten with one or more metals palladium, platinum _} rhodium, iridium, ruthenium, osmium, gold, silver, iron, nickel, chromium, lead, copper, manganese, oxides of these metals, nitrides, carbides, sulfides, and

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of which there are mixtures (USSR certificate No. 369 923) *

Graphite-based electrodes are also known, which are provided with an electrically conductive layer comprising oxides of the metals of platinum with addition of oxides of non-noble metals, in particular tin (DE Application No. 2-710 8Q2), β-manganese dioxide (DB Application No. 2 636 447), cobalt oxides of the general formula Go ^ O. (SU-certificate No. 492 301) are coated.

These electrodes are significantly cheaper than the metallic-based electrodes and their wear in the initial period of operation (generally within one month) is significantly lower than the wear of graphite anodes impregnated with an electrochemically inert material. However, as a result of the failure of the contact "electrocatalytic compound / graphite", the electrochemical process on the graphite proceeds almost completely unrestricted, and the anode is subject to wear as well as the untreated graphite anode. This disadvantage of graphite anodes containing electrocatalytic compounds is the reason why the said anodes have not found any practical application.

Object of the invention

The aim of the present invention is to develop a graphite electrode which has a long service life and is operable at industrial current densities,

Presentation of Y7esen s of the invention

The object of the present invention is to develop an electrode for electrochemical processes

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Graphite base, which has an increased life at the current densities used in industry.

This object is achieved in that the electrode, which consists of a porous graphite base, in whose pores metals or metal compounds are having electro-catalytic properties and are in electrical contact with the graphite, according to the invention in at least part of the pores of the graphite base containing electrochemically inert electrolyte-insoluble organic material having a melting point and / or transition temperature in the gaseous state higher than the temperature of the electrode in the electrolysis. It is obvious that substances, which are solid at said temperature, meet these requirements.

As an electrochemically inert organic substance, the electrode contains substances which are selected from the group Karbokettenpolymere, heterokain polymers, natural and synthetic resins, bitumen, pitches, polymerization of oils and varnishes and mixtures of these substances.

From the group of carboxyl chain polymers, the electrode may contain as inert organic substance, for example, polystyrene, polyethylene, polymethyl methacrylate, polyvinyl chloride.

From the group of hetero-chain polymers, the electrode may contain polyester acrylate.

From the group of natural and synthetic resins, the electrode may contain, as an inert substance, rosin, phenol-formaldehyde, furan and polyester resins.

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From the group of bitumen, the electrode may contain oxygenated petroleum bitumen.

From the group of pitches, coal tar pitch can be used *

From the group of polymerization products of oils and varnishes, the electrode may contain a copolymerization product of tall and linseed oil and a polymerization product of tall oil varnish *

The substances mentioned do not exhaust all possible concrete substances which can be used as inert impregnating substances.

The electrode may contain the said substances either alone or as a mixture, for example a mixture of polyethylene and paraffin or a mixture of polystyrene and polymethyl methacrylate. "

As metals or metal compounds having electrocatalytic properties, the electrode may include virtually any metals, simple and mixed metal oxides and mixtures of oxides and metals, mixtures of different oxides with each other, or mixtures of oxides with other metal compounds having an overpotential of the main electrolysis reaction lower than the overvoltage of this reaction on the graphite or at least this is the same, and do not destroy faster than the graphite under the conditions of electrolysis.

The electrode may include as said electro-catalytic substances such metals as platinum, palladium, iridium, ruthenium, mixtures, alloys and oxides thereof as well as oxides of gold, silver, iron _s cobalt, nickel, chromium,

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Copper, lead, manganese individually and in mixtures with one another and with oxides of the film-forming metals, for example titanium, tantalum, zirconium, aluminum, bismuth, tungsten, niobium, with compounds of tin, vanadium, molybdenum, silicon, carbon, phosphorus, boron and sulfur contain »

It is possible to use mixed oxides of cobalt and of the platinum group metals and the lanthanides, of mixtures of the ruthenium oxide with carbides of boron, silicon, titanium, hafnium, vanadium, tantalum, chromium and molybdenum.

The high strength of the electrode according to the invention is due to the fact that the electrochemically inert organic material not only protects the surface of the inner pores of the electrode against electrochemical and chemical destruction, but also ensures a firm and secure contact of the electro-catalytic substance with graphite.

At the same time, the presence of an electrocatalytic substance which has a lower overpotential of the main electrode reaction than graphite and the above-mentioned inert organic substance in the pores and on the surface of the graphite makes possible the size of the ones in contact with the electrolyte Significantly reduce surface area of the electrode. Thus, without exceeding the critical swelling potential, an electrode containing a larger amount of inert organic substance than in the known electrode can be used.

A further subject of the invention is a process for the preparation of a porous graphite base on an iron electrode which comprises introducing into at least part of the pores of the graphite base at least one metal and / or at least one lithium compound having electrocatalytic properties. The procedure

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characterized in that according to the invention, after introducing a metal and / or a metal compound having electrocatalytic properties into the graphite base in at least a portion of the pores of said graphite base an electrochemically inert organic material insoluble in the electrolyte having a melting point and / or a temperature of the transition to the gaseous state, which is or is higher than the temperature of the electrode in the electrolysis, or introduces or generates this organic material directly in the pores of the graphite base.

The introduction of the said organic substance can be carried out by any known method, but the preferred method is soaking as a simple and accessible method,

For this purpose, solutions of the organic material are used, with which the graphite base is saturated with subsequent removal of the solvent, or else impregnated the graphite base with a melt of said organic material, followed by cooling to the melting point of this substance.

The organic substance corresponding to said properties can be produced directly in the pores of the graphite base by impregnating this base with a liquid monomer, for example with styrene, or with a liquid oligomer with subsequent polymerization or polycondensation.

For impregnating the graphite base, solutions of polystyrene, polyvinyl chloride, polymethyl methacrylate,

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Polyethylene or melts of oxygenated petroleum bitumen, coal tar pitch, rosin and other suitable substances.

It is advantageous to carry out impregnation with unsaturated polyester resin containing isopropylbenzene hydroperoxide as a polymerization catalyst, followed by heat treatment to accelerate the polymerization. The impregnation can also be carried out with a solution of tall oil varnish in CCl, which contains a siccative, followed by drying and heat treatment for the polymerization of tall oil varnish or with a solution of tall and linseed oil in CCl. Containing a siccative, followed by drying and V / heat treatment for the copolymerization of the oils. It may also be expedient to carry out impregnation with oligoester acrylate containing benzoyl peroxide as the polymerization catalyst, followed by heat treatment to accelerate the polymerization of the oligoester acrylate or by impregnating with molten resole-phenol-formaldehyde resin, followed by heat treatment to polycondensate the resin Formation of Resit.

Other possible embodiments of the invention consist in the impregnation with a solution of polyethylene in CCl. then drying the electrode, impregnated with a mixture of mono- and difurfurylideneacetone containing 5 % para-toluenesulfochloride, followed by heat treatment to polycondensate the mono- and difurfurylideneacetone to form furan resin, impregnated with a solution of polyvinyl chloride in cyclohexanone with subsequent drying of the electrode, in the impregnation with a solution of polymethyl methacrylate in cyclohexanone with subsequent drying of the electrode, in the impregnation with molten

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zeiiera coal tar pitch, followed by cooling of the electrode below the melting point of the pitch or impregnation with a solution of polyethylene and paraffin in CCl, followed by drying of the electrode and impregnation with a solution of polystyrene and polymethyl methacrylate in styrene, followed by drying of the electrode,

The graphite used is porous graphite from which a base (block) of desired dimensions is cut out. This base is vacuumed and impregnated first with solutions of the abovementioned metal compounds, followed by drying and heat treatment, then impregnated with a solution or a melt of said organic substance,

Metals or metallic compounds having electrocatalytic properties may be incorporated in the pores of the graphite base, for example, by impregnation with solutions of the metal compounds followed by drying and heat treatment, by depositing the metals or their compounds from the gas phase, by impregnation with molten metals, or by other known methods be introduced.

Depending on the electrolysis conditions, the properties of the electrocatalytic material and the quality of the graphite, the electrode can be either • substantially completely closing the pores with the inert substance (melt impregnation, saturation with liquid monomer followed by block polymerization thereof in the pores of the electrode) or with partial filling of the pores (impregnation with solutions in volatile solvents) he / she sets forth,;

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220562 ^ ₁₁ _

The use of the electrode according to the invention has the following technical effects:

The use of this electrode instead of the ordinary graphite anodes in electrochemical production processes makes it possible to increase the life of the anodes several times, to reduce the power consumption without conversion of the electrolyzers to metallic anodes and the use of expensive and scarce metals as a basis, for example of titanium, to avoid.

The electrode according to the invention is virtually as short-circuit-proof as ordinary graphite electrodes, which is a great advantage over the metallic electrodes whose active coating dissolves in the event of a short circuit, thereby destroying the metallic base. This makes it possible to operate electrolyzers without short-circuit protection systems and to lower the demands on the purity of the electrolyte and mercury compared to the electrolyzers, which are equipped with anodes having metallic base .. The said advantages of the electrode can not be achieved if the order of introduction of the electrocatalytic substance and of the electrochemically inert organic substance into the pores of the graphite base is not adhered to.

The above sequence of operations is mandatory in the application of the method according to the invention. In the reverse order of operations, that is, when first introducing the electrochemically inert organic material, when the latter fills the entire volume of the open pores of the graphite base, the implementation of the second operation, the introduction of the elektrokatalyttischcn substance, impossible, but if the

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Graphite base is impregnated with the organic substance in part, is difficult in the subsequent introduction of the electro-catalytic substance dess.en electrical contact with the graphite base, and the graphite base is protected by nothing against the action of the electrolyte and the electrolysis products ,. In this case, the rate of destruction of the electrode from the rate of destruction of an untreated graphite base practically does not differ, which is confirmed by one of the examples given below *

As can be seen from the above, therefore, the order of operations in the methods according to the invention is not obvious with respect to known publications.

A guide example

For a better understanding of the present invention, examples of the embodiment of the electrode according to the invention and the known electrode will be given below.

Example 1

A graphite electrode according to the invention with dimensions 50 χ 50 χ 100 mm had a porosity of 20 % . The electrode was fabricated as follows: From an electrode graphite plate, cut out a block (a base) with dimensions 50 χ 50 χ 100 mm. The graphite block is vacuumed and then impregnated with aqueous solution of Co (IoOo) ₂ ^m i "t a concentration of 125 g / l> it dries then by gradually raising the temperature to 140 ⁰ G, and it glows for 10 min a temperature of 300 C. After annealing, the graphite block is vacuum-sealed and then impregnated with a

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220562 '_, _ " ^{371 r} "

Solution of polystyrene in styrene of concentration 90 g / l under a pressure of 10 at overpressure, it dries for 3 hours by gradually raising the temperature from 80 ⁰ C to 16O C, and repeats the impregnation with the polystyrene solution and drying again ,

The electrode prepared in this way contains 0.5 % Co-JO, and 1.5 % polystyrene (the polystyrene is a solid at temperatures up to 90 ⁰ G). The electrode is tested as an anode in a laboratory electrolyser in the electrolysis of a solution of HaCl concentration 280 to 300 g / l at a temperature of 80 to 85 ⁰ C and a pH of 2.5 to 3. The strength of the current flowing through the anode is 125 A (current density =

ο 5 kA / m). The temperature of the electrode during the electrolysis here and in the following examples does not exceed the temperature of the electrolyte by more than 5 C.

The weight loss of the electrode (wear) in the first 10 days of the test is 15 * 3 g »34.4 g in the second 10 days and 38.9 g in the third 10 days, giving a relative wear index of 0.0005 corresponds to g / Ah or 0.00115 g / Ah and 0.001295 g / Ah.

For comparison, known graphite electrodes containing C0.5O4 or impregnated with polystyrene and an electrode of graphite which had not been subjected to any special treatment were tested.

A graphite electrode of the dimensions described above with the same graphite basis, containing 0.5 % Co ^ O4 in the pores. ^en "kkö, 3_" k »was tested under the conditions described above. The introduction of C0.5O into the pores was analogous to that described above. The weight loss

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In the first 10 days of the test, the electrode was 18.7 g in the first 10 days, 53 g in the second 10 days, and 74.6 g in the third 10 days.

A graphite electrode of the above-described dimensions with a base of the same graphite containing 1.5 % polystyrene in the pores was tested under the conditions described above. The introduction of polystyrene was carried out analogously to the one described above. The polystyrene content of 1.5 % was chosen because it gives the maximum reduction in wear for this type of graphite under the conditions of the polystyrene only impregnation tests. The weight loss of the electrode was 31.3 g in the first 10 days of the test, 49.2 g in the second 10 days and 54.8 g in the third 10 days.

A graphite electrode of the same dimensions as the above-described electrode made of the same graphite and subjected to no special treatment (that is, identical to the base of the above-described electrodes) was tested under the conditions described above. The weight loss of the electrode was 55.2 g in the first 10 days of the test, 75.0 g in the second 10 days, and 82.1 g in the third 10 days.

example ^

An electrode according to the invention of the same dimensions as in Example 1 had a graphite base with a porosity of 20 % . In the graphite block is introduced analogously to Example 1 Co ₀ O. And impregnated with styrene. The soaking is analogous to saturation

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with the solution of Co (IIOo) ₂ ⁱⁿ Example 1. After impregnation with styrene, the block for the polymerization of styrene is gradually heated by raising the temperature from 100 ⁰ C to 140 ⁰ C within 35 h. The electrode prepared in this way contains 0.5 % COoO. and 9 % polystyrene (the polystyrene and CooO occupy virtually the entire volume of the open pores of the graphite). The electrode was tested under the conditions described in Example 1. The weight loss of the electrode was 17.2 g in the first 10 days of the test, 21.4 g in the second 10 days, and 21.6 g in the third 10 days.

For comparison, it was tested by the known method he held electrode. A graphite electrode of the above-described dimensions with the same graphite base containing 9 % polystyrene in the pores was tested under the conditions described in Example 1. The introduction of styrene and its polymerization was carried out as described above in Example 2. In the first 10 days of the test, the electrode was completely destroyed.

Example 3

An electrode according to the invention of the same dimensions as in Example 1 had a graphite base with a porosity of 20 % . In the graphite block is introduced analogously to Example 1 Co ^ O, a. Then the graphite block is vacuumed, impregnated with molten oxygenated petroleum bitumen, heated to a temperature of 220 to 230 ⁰ C, under a pressure of 10 at overpressure, The melting point of the oxidized petroleum bitumen is 135 ⁰ C. (Here and in the subsequent determined the melting point after

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Ubbelohde, see encyclopedia of polymers, Moscow, Verlag "Sowjetskaja Enziklopedija", 1974, Volume I, page 934, in Russich), The electrode thus prepared contained 0.5 % QoJ), and 9 % oxygenated petroleum bitumen (the oxidized petroleum bitumen and Co ^ O "occupied practically all the volume of open samples of graphite). The electrode was tested under the conditions described in Example 1. * The weight loss of the electrode during the first 10 days of the test was 19.3 g "in the second 10 days 21.6 g, in the third 10 days 21.7 g.

For comparison, an electrode obtained by the known method was tested. A graphite electrode of the same graphite-based dimensions described above containing 9 % oxygenated petroleum bitumen in the pores was tested under the conditions described in Example 1. The introduction of the oxidized petroleum bitumen into the pores was carried out analogously to Example 3 · In the first Ί0 days, the electrode was completely destroyed »

Example 4

A graphite electrode according to the invention of the same dimensions as in Example 1 had a graphite base with a porosity of 20 % . The graphite block is impregnated with an aqueous solution of RuCl 2 and TiCl 2 of the concentration 65 g / l, converted to RuOp, and 79 g / l, converted to TiO ₂ , and then dried. The impregnation and drying were carried out analogously to the saturation of the solution Co (10) p in Example 1. After the impregnation, the graphite block is vacuum-sealed and impregnated with 20 atm. Pressure with a mixture of the following composition: unsaturated

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220562 _ ₁₇ _

Maleinate type polyester resin modified with rosin, 50 parts by weight; Styrene 47 parts by weight; Isopropylbenzene hydroperoxide 3 parts by weight. To cure the resin, the block is gradually heated to a temperature of 100 ⁰ C and held at this temperature for 5 h.

The thus-prepared electrode contains 1.3 % of mixed oxide of ruthenium and titanium and 10 % of polyester resin (as a solid at the temperature of the electrode in the electrolysis). The resin and oxide occupy virtually the entire volume of the open pores of the graphite. The electrode was tested under the conditions described in Example 1.

The weight loss of the electrode was 18.3 g in the first 10 days of the test, 23 g in the second 10 days, and 25.4 g in the third 10 days.

Example 5

A graphite electrode according to the invention of the same dimensions as in Example 1 had a graphite base with a porosity of 20 % .

The graphite block is impregnated with an aqueous solution of H ₂ PtCl ^ concentration 55 g / lj converted to the metal. The impregnation is analogous to the impregnation with the aqueous solution of Co (Noo) ₂ i ⁿ Example performed. 1 The impregnated block is dried for 2 hours at a temperature of 100 ⁰ C and then annealed in the argon atmosphere for 1 h at a temperature of 550 ⁰ C.

After introduction of the platinum is vacuum sealed the graphite block and soaked it at a temperature of 130 ⁰ C.

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Rosin, which has a melting point of 70 ° C. The electrode produced in this way contains 0.5 % platinum and 9 % rosin. The electrode was used as an anode in a cathode protection system

- 2-

in water, which is 35 mg / 1 Cl and 40 mg / 1 SO. contains

2 tested at an anodic current density of 250 A / m and a temperature of 16 to 21 C. The relative wear rate of the electrode was 0.048 g / A, h,

A graphite electrode of the dimensions described above, made of the same graphite but not subjected to any special treatment, was tested under the conditions described above in the present example. The relative wear resistance of the electrode was 0.128 g / A.h.

Be_is_p_i £ l__6

An electrode according to the invention with the dimensions 40 × 40 × 12 mm had a graphite base with a porosity of 27 % . The electrode was fabricated as follows: From a graphite electrode plate, a block measuring 40 × 40 × 12 mm was cut out. The introduction of Go-O. was carried out in the same way as in Example 1, but the concentration of Co (ITOo) ₂ - ^{> 081111} S was 500 g / l. After the first annealing of the block, the operations of impregnation and annealing were repeated again.

After the second anneal, the graphite block was vacuum-sealed and impregnated with a solution of tall oil varnish in CCl, the 15% by volume Tall'dlfirnis, and a lead-manganese siccative at 0.45 % after the pyrolusite and OyS % after the litharge , related to the Ge «-

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Then the block was dried under vacuum for 3 h at room temperature, 3 h with gradual increase in temperature from room temperature to 90 C and to constant weight at a temperature of 90 ⁰ C without vacuum. The Elek produced in this way

It contains 8 % Go ^ O and 3 % polyraerization product of tall oil sirloin (decomposes above 260 C to form gaseous products). The electrode was tested under the conditions of preparation of sodium chloride in an electrolyte containing 130 g / l HaCl, 450 g / l NaC10 and 2 g / l at a pH of 6.6 to 7, 6, one

Temperature of 40 G and a current of 5.1 A.

The weight loss of the electrode was 0.9 g in the first 10 days of the test, 1.2 g in the second 10 days, and 1.3 g in the third 10 days.

For comparison, under the same conditions, known electrodes as well as an electrode made of graphite, which was not subjected to any special treatment, and an electrode made of graphite by a method in which the said order of operations was not observed were tested.

A graphite electrode of the dimensions described above, having a graphite-like basis and containing 8 % Co 2 O 3 in the pores, was tested under the conditions described above. The introduction of Co ^ O. The weight reduction of the electrode was 1.5 g in the first 10 days of the test, 2.7 g in the second 10 days, and 4.6 g in the third 10 days.

A graphite electrode of the same dimensions as that described above with the same graphite base,

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which contains in the pores 3 % polymerization product of tall oil sirloin, was tested under the conditions described above. The impregnation with the solution of tallow oil and the heat treatment were carried out as described above. The weight loss of the electrode was 1.1 g in the first 10 days of the test, 1.9 g in the second days, and 2.4 g in the third 10 days.

A graphite electrode of the same dimensions as that described above having a graphite-based base which was not subjected to any special treatment was tested under the conditions described above. The weight loss of the electrode in the first 10 days of the test was 2.4 g, in the second 10 days 2.8 g, in the third 10 days 4 »6 g.

To a graphite base of the dimensions described above, prepared from the same graphite, the polymerization product of tall oil siren was prepared as described above in Example 6 and then described as in Example 6 above

ben CooO. on.

The prepared electrode was tested under the conditions described above.

The weight loss of the electrode was 2.2 g in the first 10 days of the test and 2.75 g in the second 10 days

in the third 10 days 4 _? 6 g »

Example 7

A graphite electrode of the invention described in Example 6 had a graphite base with a porosity of 27 % . In a graphite block

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you brought 0oS>. analogous to Example 6, then vacuum-sealed the graphite block and soaked it with a mixture of the following composition: tall oil 10.5 parts by volume, linseed oil 4.5 parts by volume, CCl. 85 parts by volume. To the mixture was added a lead I'.Tanganese siccative in an amount of 0.5 % after the pyrolusite and 1.0 % after the litharge, based on the weight of the tall oil. Thereafter, by drying the block as well as after the impregnation with the Tallölfirnislösung (Example 6) The electrode thus obtained contained 8% Co ₃ O and 3% Kopolymerisationsprodukt of tall oil and linseed oil (decomposed calibration over 260 ⁰ C to form gaseous products ). The electrode was tested under the conditions described in Example 6.

The weight loss of the electrode during the first 10 days of the test was 0.7 g »in the second 10 days 1.3 g»

in the third 10 days 1.5 g «

Example 8

A graphite electrode of the invention described in Example 1 had a graphite base with a porosity of 20 % . The graphite block was impregnated with an aqueous solution containing 17.5 g / l RuCl and 30 g / l Te (OH) ₃ , prepared by precipitation from the solution of FeCl 2 with ammonia. The impregnation was carried out in the same way as the impregnation with the solution of Co (UOo) ₂ in Example 1. Thereafter, the dried

phitblock for 1 h at a temperature of 100 ° C, the temperature increased for 1 h uniformly to 450 ⁰ C and held the block at 450 ⁰ C for 1 h.

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The block treated in this way was impregnated with oligoester acylate based on phthalic anhydride, triethylene glycol and 1-methacrylic acid containing 2 % of benzoyl peroxide. The impregnation was carried out analogously to impregnation with styrene in Example 2. The block was kept for 3 h at one to form the polyester acrylate Temperature of 80 ° C. and 3 hours at a temperature of 100 ° C. The electrode thus prepared contained 0.3 % of a mixture of oxides of ruthenium and iron and 10.5 % of polyester acrylate (a solid at the temperature of the electrode in the electrolysis ). The electrode was tested under the conditions described in Example 1. The weight loss of the electrode in 10 days of the test was 20.2 g.

An inventive grave electrode of the dimensions described in Example 1 had a graphite base with a porosity of 20 % . The graphite block was impregnated successively first with an aqueous solution of IvIn (I ¹ IOo) ₂ -with a concentration of 52 g / l with subsequent drying within 1 h at a temperature of 100 ⁰ C and annealing within 10 min at a temperature of 190 ⁰ C, and then it was impregnated with an aqueous solution of Co (IiOo) ₂ at a concentration of 65 g / l, followed by drying and annealing. The impregnation with the aqueous solutions and the drying and annealing after impregnation with the solution of Co (! TOo) p were carried out analogously to Example 1

The thus-treated block was vacuumed and placed in molten resole-phenol-iodine-aldehyde resin, heated to a temperature of 80 G, and then formed over the molten resin. Argon pressure of

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10 at overpressure and carried out the impregnation at the said pressure and the said temperature within 2 h. Then took the graphite block from the resin out, removed the excess resin from the surface, and subjected to block a Wärmebehandlung'zur curing of the resin by C raised the temperature of SO ⁰ to 130 ⁰ C at a rate of 3 ° C / h ·

The electrode prepared in this way contained 0.5 % of a mixture of MnOp and Co ^ O- in a ratio of 1: 1 and 7 % of phenol-formaldehyde resin (a solid at the temperature of the electrode in electrolysis) Electrode was tested under the conditions described in Example 1 *

The weight loss of the electrode was 13.5 g in the first 10 days of the test, 20.2 g in the second 10 days, 20.6 g in the third 10 days,

Example 10

A graphite electrode of the invention described in Example 1 had a graphite base with a porosity of 20 % . The graphite block was impregnated with a solution of RuCl3 at a concentration of 35 g / l with subsequent heat treatment. Impregnation and heat treatment were the same as when the mixture of ruthenium and iron was introduced (Example 8). The graphite block was then immersed in a boiling solution of polyethylene in CCl * at a concentration of 110 g / L and refluxed for 4 hours. Thereafter, the block was soaked with said solution of polyethylene under a pressure of 10 at overpressure at a temperature of 75 C within 4 H.

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Thereafter, the block was soaked with the said solution of polyethylene under a pressure of 10 at overpressure at a temperature of 75 C within 4 h. After impregnation, the graphite block was dried for 1 h at a temperature of 70 ° C. for 1 h at a temperature of 100 ^° C. and for 1 h at a temperature of 200 ^° C. The electrode prepared in this way contained 0, 2 % RuO "and 1 % polyethylene (a solid at the temperature of the electrode in electrolysis). The electrode was tested as an anode in a laboratory electrolyser for the production of IT sodium hypochlorite. The electrolyte contained 90 g / l NaCl and 10 g / l NaGlO. The electrolysis was carried out at a temperature of 25 C and a current density of 2 kA / m. The weight loss of the electrode was 63 g in 10 days of the test.

For comparison, under the same conditions, an electrode of the same dimensions was prepared, which was made of the same graphite but was not subjected to any special treatment. The weight loss of the electrode was 150 g in 10 days of the test.

Example 11

A graphite electrode of the invention described in Example 1 had a graphite base with a porosity of 20 % . Analogously to Example 10, RuO _{2 was introduced} into the graphite block, then the mixture was vacuum-cured and impregnated with a mixture of mono- and difurfurylideneacetone in the ratio 3: 2, which contains 5 % of para-toluenesulfochloride.

The soaked block was heated .1 hours from room temperature to 80 C, then increased the Temper door 80 ⁰ G ⁰ to G I50 at a rate of

7. 11. 1980 57 371/17

220562

- 25 -

10 degrees / h and held the block for 3 h at a temperature of 150 ⁰ C.

The electrode prepared in this way contained 0.2 % RuOp and 8.5 % furan resin (a solid at the temperature of the electrode in the electrolysis). The electrode was tested under the conditions described in Example 5. The relative rate of weight loss of the electrode was 0.056 g / Ah.

Example 1 2

A graphite electrode according to the invention of the dimensions described in Example 1 had a graphite base with a porosity of 20 % . In the graphite block was introduced analogously to Example 5 platinum. Thereafter, the block was soaked in a 2 / Sigen solution of polyvinyl chloride in cyclohexanone (the impregnation was carried out the same as the impregnation with the polystyrene solution in Example 1) and dried for 3 h at a

ο Temperature of 90C. The saturation and drying operations were repeated by extending each shark the duration of drying by one hour to obtain a weight gain of 2 % (based on the weight of the base).

The electrode prepared in this way contained 0.5 % platinum and 2 % polyvinyl chloride (the polyvinyl chloride decomposes above 90 ° C to form gaseous products). The electrode was tested under the conditions described in Example 1.

7. 11. 1980 57 371 /. 17

The weight loss of the electrode was 16.7 g in the first 10 days, 31.3 g in the second 10 days and 33.2 g in the third 10 days.

Bei Piel 13

A graphite electrode of the invention described in Example 6 had a graphite base with a porosity of 20 % . The graphite block was vacuumed and impregnated with an aqueous solution of 20 g / l, dried

For 1 h at a temperature of 100 C and 1 h at a temperature of 150 C, he boiled for 2 h in concentrated hydrochloric acid, 2 h in water and dried for 1 h at a temperature of 150 C. Then brought into the graphite block RuO ₀ , analogous to that described in Example 10, a.

C.

Thereafter, the graphite block was vacuum-sealed and impregnated with a solution of polymethylmethacrylate in cyclohexanone at a pressure of 20 g / l at a pressure of 20 g / l, then the block was dried for 2 hours at a temperature of 150 ° C. and for 1 hour at a temperature of 170 ° C, The impregnation with the polymethyl methacrylate solution and the drying were repeated until a weight gain of 1.2 % was reached *

The electrode thus obtained contained 0.1 % SiO 2, 0.2 % RuO ₂ and 1.2 % polymethyl methacrylate. The electrode was tested under the conditions described in Example 6.

The weight loss of the electrode was 1.0 g in the first 10 days of the test, 1.5 g in the second 10 days, and 1 $ 7 g in the third 10 days.

7 "11. 1980 57 371/17

- 27 - Ex a mp 14

A graphite electrode according to the invention of the dimensions described in Example 1 had a graphite base with a porosity of 20 % on the graphite block soaked in an aqueous solution containing 41.5 g / l Co (HO ₃ ) ₂ and 97.2 g / l Al (IIOo) 3 contained. The Durchtränlcung was carried out analogously to the Durchtränlcung with the solution of Co (IIOo) ρ in Example 1. The impregnated block was gradually heated to a temperature of 120 ° C, held at 120 ° C for 1 h, then gradually heated to 450 ^° C and kept at that temperature for 2 h. Then, 0.2 % RuOp, analogous to that described in Example 10, was introduced into the base. The graphite block treated in this way was vacuumed and then heated with coal tar pitch (melting point 95 C), to a temperature of 220 C and impregnated at 10 at overpressure.

The electrode prepared in this way contained O _S 5 % of a mixture of aluminum and cobalt oxide, 0.2 % RuOp and 11.5 % coal tar pitch. The electrode was tested under the conditions described in Example 1. The weight loss of the electrode was 22.5 g in 10 days of the test.

Example 15

A graphite electrode according to the invention of the dimensions described in Example 6 had a graphite base with a porosity of 27 % . To the graphite base was added 2.4% mixed oxide of ruthenium and titanium by impregnation with aqueous solution of RuCl 2 and TiCl 2, followed by drying and annealing as described in Example 4. Then you got into the basics

7 * 11. 1980 57 371/17

1 % of a mixture of paraffin (melting point 55 C) and polyethylene in the ratio 1: 1 by impregnation with a solution of 55 g / l polyethylene and 55 g / l paraffin in CCl, a "The impregnation and drying were analogous to the introduction of Polyethylene performed in Example 10.

The electrode prepared in this way contained 2.4% mixed oxide of ruthenium and titanium and 1 % of a mixture of paraffin and polyethylene (the mixture is a solid at the temperature of the electrode in the electrolysis). The electrode was tested under the conditions described in Example 10. The weight loss of the electrode was 54.2 g in 10 days of the test.

Example 1G

A graphite electrode according to the invention the dimensions described in Example 1 had a base made of graphite having a porosity of 20 ^ ^1. Co-0 was introduced into the graphite block. analogous to Example 1, then impregnated the block with a solution of polystyrene (80 g / l) and polymethyl methacrylate (10 g / l) in styrene, stabilized with hydroquinone "The impregnation and subsequent drying were just as v / ie in the Impregnation with the solution of polystyrene in styrene performed in Example 1 «. The saturation and drying operations were carried out twice.

The EMctrode prepared in this way contained 0.5 % CO-jO, and 1.5 % of a mixture of polystyrene and polymethyl methacrylate (the mixture is a solid at the temperature of the electrode in the electrolysis). The electrode was tested under the conditions described in Example 1 performed. The weight reduction of the electrode

7. 11. 1980 57 371/17

in the first 10 days of the test was 16.6 g, in the days 10 days 34 _} 7 g> in the third 10 days 37.3 g ·

For a clear illustration of the essence of the invention, the results of testing the electrodes in the electrolysis of NaOl with a concentration of 280 to 300 g / l at 80 to 85 ° C (conditions of production of chlorine and caustic soda) and under the conditions of Preparation of Sodium Chlorate Listed in Tables 1 and 2, respectively »

The examples given show that the electrode according to the invention has significant advantages over the known graphite electrodes, wherein the effect of reducing the wear rate of the electrode according to the invention is not a summary effect. Thus, for the known electrodes of Example 1, the average wear rate in the period of 20 to 30 days after the start of the tests (in the time when the wear rate is close to the stationary ones) was SO, 9 % and 66.7, respectively % of the average wear rate of the untreated graphite electrode in the same period. When combining the electrocatalvic substance and the inert organic substance in the pores of the electrode, it could be expected that the wear rate would be 60.6 % of the wear rate of the untreated electrode. In fact, it was only 47 »4 fo, meaning it was 1.3 times lower, which is a surprising, unexpected effect. An even more surprising effect is the reduction by a multiple of the stationary wear rate of the electrode in combining the known impregnating agents in such amounts, each of which individually has a very low positive effect.

7. 11 · 1980 57 371/17

or leads to an acceleration of wear. Thus, the introduction of 0.5% G03O / (Example 1) reduces the steady state wear rate by 1.1 times. The incorporation of 9 % polystyrene (Example 2) or 9 % oxidized petroleum bitumen (Example 3) resulted in an 'increase in wear rate up to a catastrophic level'. Nonetheless, the steady state wear rate of the electrode was 0.3%. Co ₃ O ₄ and 9 % polystyrene (Example 2) or 0.5 % Co ₃ O.

and 9 % oxygenated petroleum bitumen (Example 3), 3 »5 times lower than that of the untreated electrode.

Table 1: Test results of the graphite-based electrodes with a porosity of 20 % under the conditions of the electrolysis of ITaCl solutions of concentration 280 to 300 g / l at 80 to 85 C.

Kr. Des Electrocatalytic additive Inert organic matter Wear of the anode (g) during the test in days 10 to 20 20 to 30 At play - - 0 to 10 75.0 82.1 1 0.5 % Co-O. - 55.2 53.5 74.6 1 1.5% polystyrene 18.7 49.2 54.8 1 0.5 % Co ₃ O ₄ 1.5% polystyrene 31.3 34.4 38.9 1 - 9% polystyrene 15.3 - 2 0.5% Co, 0. 9 % polystyrene complete destruction 21.4 21.6 2 9 / S oxygenated petroleum bitumen 17.2 - - 3 0.5% Co ₃ O ₄ 9 % oxygenated petroleum bitumen complete destruction 21.6 21.7 3 1.3 # TiO ₂ + RuO ₂ 10 % polyester resin 19.3 23.2 25.4 4 0.3% ee ₀ O ₄ + RuO ₂ 10.5 % polyester acrylate 18.3 - - 8th 0.5 % IvInO ₂ + Co ₃ O ₄ 7 % phenol-formaldehyde resin 20.2 20.2 20.6 9 0.2 % RuO ₂ 8.5 % pure resin 18.5 22.8 23.2 10 0.5 % Pt 2 % polyvinyl chloride 17.3 31.3 33.2 12 +0.2 % RuO ₂ ) '11, 5 % coal tar pitch 16.7 - - 14 0.5? S Co ₃ O ₄ 1.5 % Geraisch of polystyrene 22.5 16 with Polyinethylmethykrylat 34.7 37.3 16.6

-i CO -J O

Table 2: Test results of the graphite-based electrodes with a porosity of 27 % under the conditions of production of ITatriumchlorat

ITr. of the Bei Electrocatalytic additive Co ₃ O ₄ Inert organic matter - Wear of the anode (g) during testing in centers 10 - 20 20 - 30 , game 0-10 2.8 4.6 6 ⁺ Polyraerisationspro- 2.4 2.7 4.6 6 * 8 % Co ₃ O from Tallölfirnis 1.5 6 ⁺ 3 ss PoliTiierisationspro ~ 1.9 2.4 CoO ^! domestic product from Tallölfirnis 1.1 6 8 % -3 C / Kopolymerisationspro- 1.2 1.3 % SiO ₂ 0.2 % I? UO ₂ domestic product of tall and linseed oil 0.9 7 ^: 8 % % Polymethylmethane 1.3 1.5 domestic product acrylate 0.7 13 0.1 1.2 1.5 1.7 1.0

'known electrodes

VJI VjJ

CO O

Claims (17)

invention claim Electrochemical process electrode consisting of a porous graphite base, containing in at least part of its pores metals or metal compounds having electrocatalytic properties and being in electrical contact with graphite, characterized in that they are present in at least part of the pores the graphite base contains an electrochemically inert organic substance which is insoluble in the electrolyte and which has a melting point and / or a temperature of the transition to the gaseous state which is higher than the temperature of the electrode during the electrolysis or 2 # Electrode according to item 1, characterized in that it comprises al3 electrochemically inert in the electrolyte-insoluble organic substance a substance selected from the group Karbokettenpolymere, heterokain polymers, natural and synthetic resins, bitumen, pitches, polymerization of oils and varnishes, and mixtures of contains these substances, 3 »Electrode according to point 1, 2, characterized in that it contains polystyrene as the electrochemically inert in the electrolyte insoluble organic substance · 4 »electrode according to item 1, 2, characterized in that it contains as electrochemically inert in the electrolyte insoluble organic substance polyethylene. Te 11, 1980 57 371/17 ^ -34- 5 * Electrode according to item 1.2, characterized in that it contains polymethylmethacrylate as an electrochemically inert organic substance which is insoluble in the electrolyte « 6. Electrode according to point 1, 2, characterized in that it contains as electrochemically inert in the electrolyte insoluble organic substance polyvinyl chloride, 7e electrode according to item 1, 2, characterized in that it contains polyester-acrylate as electrochemically inert electrolyte-insoluble organic substance, 8, electrode according to item 1, 2, characterized in that it contains rosin as the electrochemically inert organic substance insoluble in the electrolyte, 9. The electrode according to item 1, 2, characterized in that it contains phenol-formaldehyde resin as an electrochemically inert in the electrolyte-insoluble organic material. 10. The electrode according to item 1, 2, characterized in that it contains furan resin as electrochemically inert in the electrolyte-insoluble organic substance, 11. Electrode according to item 1, 2, characterized in that it contains polyester resin as the electrochemically inert organic material which is insoluble in the electrolyte. 12. Electrode according to item 1, 2, characterized in that it contains petroleum bitumen oxidized as electrochemically inert organic material which is insoluble in the electrolyte, 7. 11. 1980 57 371/17 13. The electrode according to item 1, 2, characterized by the fact that it contains copolymerization product of tall and linseed oil as the electrochemically inert organic substance insoluble in the electrolyte. 14. The electrode of item 1, 2, characterized in that it contains as' electrochemically inert insoluble in the electrolyte organic material polymerization product of tall oil sirloin. 15 * electrode according to item 1, 2, characterized in that it contains coal tar pitch as electrochemically inert in the electrolyte insoluble organic matter. An electrode according to item 1, 2, characterized in that it contains a mixture of polyethylene and paraffin as the electrochemically inert organic substance insoluble in the electrolyte. '. , 17. The electrode according to item 1, 2, characterized in that it contains a mixture of polystyrene and Polymethylmethakrylat as electrochemically inert in the electrolyte-insoluble organic material, 18. A method for producing an electrode for electrochemical processes according to the items 1 to 17, which has a porous graphite base, the introduction into at least part of the pores of the graphite base of at least one metal and / or at least one metal compound, the electrolytic properties characterized in that in at least a part of the pores of the graphite base after the introduction of a metal or a metal compound having electrocatalytic properties, in this an electrochemical inert in the 7 · 11. 1980 57 371/17 Electrolytes introduces insoluble organic matter having a melting point and / or transition temperature in the gaseous state which is higher than the temperature of the electrode during electrolysis, or is, or generates this directly in the pores, 19 »The method according to item 18, characterized in that .man performs the introduction of the electrochemically inert in the electrolyte insoluble organic material by their impregnation with a solution or a melt under heat treatment. Process according to item 19, characterized in that a 3 electrochemically inert electrolyte-insoluble organic substance having a melting point and / or a temperature of transition to the gaseous state is at or above the temperature of the electrode the electrolysis is impregnated in the pores of the graphite base, the graphite base with a liquid monomer or a solution of a monomer in an organic solvent, followed by polymerization or polycondensation, Process according to item 19, characterized in that, in order to produce an electrochemically inert organic substance which is insoluble in the electrolyte and which has a melting point and / or a transition temperature to the gaseous state, the temperature is higher than the temperature of the electrode In the pores of the graphite base, the graphite base is impregnated with a liquid oligomer or a solution of an oligomer in an organic solvent with subsequent polymerization 7. 11. 1980
57,371 / 17 220562 - 37 or polycondensation. 22. The method according to, points 18 and 19, characterized in that the impregnation with a solution of
, Polystyrene in styrene performs subsequent drying of the electrode. Method according to points 18 and 20, characterized in that the impregnation with styrene is carried out with subsequent thermal polymerization thereof. 24 «Method according to points 18 and 19, characterized in that one carries out the impregnation with molten oxidized petroleum bitumen, with subsequent cooling below the melting point of the Erdbitbitumeiis. Method according to points 18 and 21, characterized in that the impregnation with unsaturated polyester resin containing isopropylbenzene hydroperoxide as a polymerization catalyst is carried out, followed by heat treatment to accelerate the polymerization, 26. Method according to points 18 and 19 »characterized in that the impregnation with molten
Rosin undergoes subsequent cooling below the melting point of the rosin. Process according to points 18 and 21, characterized in that the impregnation with a solution of
Tall ölirnis in CCl., Which contains a siccative, followed by drying and heat treatment for the polymerization of tall oil varnish. · 7 · 11. 1980
57,371 / 17 28 .. The method according to points 18 and 20, characterized in that the impregnation with a solution of
Tall and linseed oil in CCl, which contains a siccative, followed by drying and heat treatment for the copolymerization of the oils » 29 .. Process according to items 18 and 21, characterized in that the dehydration impregnation with oligoester acrylate,
which benzoyl peroxide as a polymerization catalyst
contains, under subsequent heat treatment
to accelerate the polymerization of Oligoesterakrylates. 30.The method according to items 18 and 21, characterized in that the impregnation with molten resole phenol-formaldehyde resin is carried out with subsequent heat treatment for the polycondensation of the resin to form Resit « 31. Method according to points 18 and 19 »characterized in that the impregnation with a solution of
Polyethylene in CCl, with subsequent drying of the electrode. 32. The method according to points 18 and 20, characterized in that the impregnation with a mixture of
Mono- and Difurfurylidenazeton containing 5 % para-toluenesulfonyl chloride, followed by heat treatment for polycondensation of the mono- and Difurfurylidenazetons to form furan resin, 33 »Method according to points 18 and 19, characterized in that the impregnation with a solution of
Polyvinyl chloride in cyclohexanone, followed by drying of the electrode, 7. 11. 1980 57 371/17 34 »method according to the points 18 and 19» characterized .durch by performing the Durchtränlcung with a solution of Polymethylinethakrylat in cyclohexanone, followed by drying of the electrode. Method according to points 18 and 19, characterized in that the penetration is carried out with molten stone carbon monoxide, with subsequent cooling of the electrode below the melting point of the pitch. 36 * Method according to items 18 and 19 », characterized in that the impregnation with a solution of polyethylene and paraffin in CCl. followed by drying of the electrode. 37. Method according to items 18 and 19 »characterized in that the impregnation is carried out with a solution of polystyrene and polymethylene ethoxylate in styrene, followed by drying of the electrode.