DE2035863A1 - Electrode for chlor-alkali electrolysis and process for its manufacture - Google Patents

Description

VEB CHEMIEEOMBINAT BITTEEFELD Bitterfeld, Jan. 7, 1970

4-04.20 / 1496

Inventor: Prof. Dr. Hans Hofmann, Halle Dr. Joachim Barthel, Freiberg Dr. Hermann Kögel, 'Kirchberg

Electrode for chlor-alkali electrolysis and process for its manufacture

The invention relates to a multilayer electrode for chlor-alkali electrolysis and a process for the production of the electrode

For electrolyte processes such as chlor-alkali electrolysis, insoluble or sparingly soluble Anodes needed that differ in their properties and Do not change dimensions over a long period of time. The graphite electrodes used on an industrial scale have the disadvantage that, due to the co-deposition of oxygen in addition to chlorine, oxidation of the graphite and, in addition, due to the porosity of the graphite anodes, a slow mechanical process Destruction occurs. This wear and tear limits the service life of the anode the bath voltage increases, especially with the vertical

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cells, depending on the running time. The fine-grained abrasion of the anode gets onto the diaphragm and when it is used in diaphragm cells reduces its permeability in the course of time, so that the bath resistance increases «In addition to a renewal The anodes therefore also require changing the diaphragms at certain time intervals.

It is also known that platinum is also used as the anode material in chlor-alkali electrolysis leaves, where earlier platinum foils or wires and now platinum-coated titanium electrodes or platinum-coated electrodes made of another passivatable metal or alloys such metals are known and are also used, other metals of the platinum group in addition to platinum or their alloys or oxides can be used.

The use of platinum metals for technical electrolytic chlorine production has the disadvantage that for the equipping of electrolysis systems with such anodes in spite of a platinization layer of very low strength, considerable quantities of precious metal are required and thus a high investment outlay connected is. Another disadvantage of such platinized anodes is the loss of precious metal due to the low resolution of the platinum in the. course

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of electrolysis · The loss of platinum, can "up to 500 mg per tonne of chlorine · A recovery of the in Solution gone platinum is mostly not possible·

It is also known to use molten magnetite anodes. Due to the manufacturing method the anodes can only be used in limited spatial dimensions to be poured · Besides, they are due to their Brittleness mechanically very sensitive · The disadvantages are the reason for the replacement of the magnetite anodes duroh Carbon or graphite anodes

The application of magnetite to metals prepares extraordinary difficulties · Magnetite, for example, reacts to thermal deposition Titanium with the metallic base · This becomes removes the good resistance of magnetite to the electrolyte and the electrolysis products Electrolytic deposition of magnetite on metals is not possible

The purpose of the invention is to create multilayer electrodes for the chlor-alkali electrolysis to provide the chemical and electrochemical attack as well withstand mechanical stress. Furthermore, by using less expensive Material achieved a reduction in investment costs

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The invention is die'Aufgabe augriinde, monopolar or bipolar Mehrsohiohtelektrodea for Ghloa> · alkali electrolysis to develop and hersuetellen ₉ to conduct the electricity well and a chemical or electrochemical little vulnerable Außeneehioht be "sitting ·

According to the invention, the monopolar electrode consists of a titanium lead, which should be emitted on one or both sides with magnetite powder or with a © - from Magnet it powder is coated with powdered thermoplastic materials. A litan lead can be used as a bipolar © electrode which is on one side with magnetite powder © which is old to the "before ^ aanatea powder mixture" ad m £ & ®r "aMerea side with a non-peeaivlerfcflvea metal® The bipolar slectrode can be made into a sheet of copper beiteh @ n ₉ am m ® £ one side is plated with a fitanbleoh and the other side is covered with a glass cover & ug »Bi @ titanium side is coated with magnetite powder or with the mentioned powder mixture

Is has been found to be good h & fteade and-sen Electrically conductive coatings on ü @ part @ ii iurslivon Procedures where

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One such procedure is, for example Experiencing an explosion. According to the invention, the explosive process can also be applied to powdery coating materials, such as magnetite powder or magnetite polytetrafluoroethylene powder mixtures apply · The powdery substances are surprisingly in the application of the process does not depend on the developing beam carried along, but pressed into the metal by the shock waves. From the close connection between the powdery particles and the titanium sheet results in a good conductivity or a very low contact resistance.

Depending on the amount of powdery substance used the particles are only pressed into the titanium, or, if more powder is used, the particles will not come into direct contact with the titanium can be pressed together to form a firm layer adhering to the pressed-in particles, which can have a thickness of several millimeters

A layer of powdery substances applied after the explosion process adheres very well to the metallic one Underlay and can also be mechanically, for example by bending the coated titanium sheet, to be claimed

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By mixing the magnetite powder to be applied. rad leaves, characterizing the adhesion strength ier © iHselaeß Seilohem • among themselves verb@ss.ert Nooh which - with a thermoplastic material, such as Polyvinylchloridj polythene, Polytetr & fluqv & then, in an amount noeii a iiralrteii Kentelrfe the individual Xeilohen of leiteaden powdery substance to " Porosity & it not be reduced «In the Hegel up to 5 % thermoplastic material @ uge @ i

The © coating of the fitaafeleoh, ©haben kmm © laofe. w two - · pages either individually Upper Austrian @ r moving & hseitig © rfolgea © The equilateral mutual coating the powder on a Stciilplatte is s ^ ^ ifgastreut the sweck- advantageously with ßraphitpulves? sprinkled © ä © a? »It a graphite emulsion eingeis-ferioken IST® Badurcli a © plating of the base Termieäe""About the powder is a Titanbleoh attached ₉ welohe © is also demonstrated with Puliw. DEraiaf is © ine rubber? · Oier limst st off mat with a Sprengstoffsohieiit geg © feea _ffi laughing, the "! Detonation both sides with magnetite coated Is Amoli • is possible two Titaableohe gleioliseitig © lnü © ITIG su be" layers j by wipe the Mlv @ r @ © hioht © n powder is sprinkled ©

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The one or uütanbleohe coated on both sides are suitable as monopolar electrodes for chlor-alkali electrolysis «

The bipolar electrode, which is used as an electrode in the chlor-alkali electrolysis cells is used with ion exchange membrane, is according to the invention from a titanium-plated Made of copper sheet, its titanium core in the shock wave process with magnetite powder or a mixture of magnetite with powdery thermoplastics Coated materials and on its copper side in known way nickel, for example electrolytically, "A titanium sheet can also be used as a bipolar electrode" which is deposited on one side Side was coated with magnetite powder or with the aforementioned mixture after the explosion process is and on the other hand with a non-passivable Metal, for example Niokel, provided let «

For increased protection of the coated surface, the powder that is not in direct contact with the Titanium Bleoh can be removed again and the Sheet metal can be straightened if necessary · Then a Mixture of magnetite powder with thermoplastic material and applied by a known method sintered on. The mixture can knuckle-headed catfish

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ORIGINAL INSPECTED

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also consist of magnetite powder with substances that are in the heat will condense the resulting condensate product can be an epoxy resin, for example «

The invention is to be closely related to the execution be! play explained in more detail

Example 1ε

The monopolar electrode consists of a hand-held one White-annealed ÜÜtanbleoh from 1.5 to 2.0 mm Strength on which magnetite is pressed in on one side by the explosive process »On the layer is an approximately 1 mm thick ifiagnetitsohioht with a Share of 5 Grewiohtsprosent®n polytetrafluoroethene arranged " The electrode produced in this way has a low ohmic resistance and w @ iat in the Chlor-alkali electrolysis has a low overvoltage for chlorine and a sufficiently high overvoltage for Oxygen on

Example 2:

The bipolar electrode consists of a 1.0 mm thick copper sheet, which is _{plated with an O 9} S mm thick titanium bleoh let · Bas litanbleöh as in Example 1 besohiolrfeat, while the lupferbleeli is electrolytically nickel-plated «

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Example 3:

A commercially available titanium sheet with a thickness of 1.5 to 2 mm, which is annealed, is degreased and pickled using known methods Steel plate, which serves as an anvil, is ground 6 ml

2 ■
Sohmelzmagnetit applied per dm of surface to be coated with a grain size of 0.5 to 0.75 mm in an even layer. The titanium leoh is placed at a distance of 1 to 2 mm from the surface of the Fulverso layer, and an equal *

A moderate layer of 95 g of Donarite per dm, which is separated from the titanium by a plastic plate, won "After the detonation of the explosive substance, the downward-facing side of the titanium bleohes is coated with a dense layer of magnetic pressed in ·

Example 4:

A Titanium Bleoh.-is, as described in Example 3, with magnetite, the one with 5 percent by weight polytetrafluoroethylene is mixed, coated · Bach's detonation is magnetite in the bottom of the titanium sheet pressed in, and on this layer an "approximately 1 mm thick magnetite layer is extensively pressed, which is sintered with polytetrafluoroethylene "

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Example 5: According to. Example 3 becomes a Titan Bleoh n & oh tem Ikplosive «»

process with a thin magnetite layer verseliea® .

The Megaetiis not pressed into the metal - will.

with mechanical coats, for example, or Sohaben removed again "The surface is detzt with a thin layer crimped which is provided in direct contact with the Titambleela" The plate is covered gegebenenfal äthenpulver with a uniform layer of a Magnetitpulvex "5 GewielitsproseBteB" The Leg

echioht is ansohließeaä tnroli irwSxmeB © isf 3 © 0 htm

400 ⁰ O in 20 ÜairteE a

Example 6s

For simultaneous mutually © BeB © M © Ss.t 'Titanbleohes additionally zn AEET ÄnoTämnm§ _s is as described in Example 3 _s the flt @ all ©© & eia ©

equally thin sohioht

äthen ^ Fulver applied and with

covered »Bsraiif will '© ia @

layer given® IßöJti des? Detonati © ^ is aiaf sides of the Sitanbleohss Magnetit © isgsp? ©! ^ WsM with a ca * 1 mm thick laga © titsohi @ Sit wmsm®h®m _s oil is sintered with Polytetrsfluoräthsn «,

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Example 7ί

Sin copper sheet with a thickness of 4 m is means the well-known explosive plating with a bleoh Titanium plated, the latter »being 2 mm thick has · The produced copper-titanium-bleoh is made up to cu one Thickness of about 1.5 mm rolled out. Then the Side with the titanium coated with magnetite according to Examples 3 to 5 nickel-plated

Example 8:

A layer of magnetite is applied to a titanium bleoh Braoht, Grefit powder is sprinkled over it, on top magnetite is given again at a distance of 1 to 2 mm from the surface of the powder layer a titanium Sheet attached to the luad accordingly Example 3 Applied Explosives Cured "Haoh the detonation of the explosive are both titanium sheets with a thick layer of the pressed in Magnetite occupies and can be grounded separately.

Example 9s

10 ml of Sohmeljsmagnetite per dm ^{2 are placed} on a permanently magnetic steel plate. 100 g of Donarite per dm ^{2 are placed} on a plate made of titanium bleoh with 100 g of Donarite per dm 2 on the plate

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shot. This gives the titanium sheet a thick coating of pressed-in magnetite

Example 10ϊ

A magnetic * rubber mat is placed on a sheet of steel · Put 10 ml of enamel on the "rubber mat" magnet

magnetite powder scattered per dm · The The combination is ejected as a moving plate onto a titanium sheet as a base · Bas Titanbleoh thereby receives a coating of magnetite

Example 11:

A mixture of magnetite powder is added to a magnetite layer applied after the explosive ^1; Polycondensable substances are applied and the condensation is carried out in the heat.

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Claims (1)

VEB OHEMIBKOMBIHAT BIÜEERFEED P 20 55 863.8 Claims ^ ί ; 1 Zb, -77. 1. Electrode for chlor-alkali electrolysis, characterized in that that a titanium sheet with a firmly adhering coating of magnetite powder or a powdery mixture of magnetite and polymerized or polycondensed Material is coated. 2. Monopolar electrode according to claim 1, characterized in that one or both sides of the "HtstÄleehes with magnetite powder or with the powdery mixture of magnetite and polymerized en baw» material is coated # 3 · Bipolar .electrode Gael! Μ £ τ> τα.Φ- 1 _? draws that eisa fitaatelea ". eissseifig E Copper sheet, clad, the over side ffii'i üTickelüberzug provided 'and .the Sitaaseite with lagaetitpulver or with the powdery mixture of the Magaetii. and polymerizes en bsw. polycondensation material. is coated «, 4. Electrode according to one of claims 1 Ms 5 _$ € aäuroli. marked »that -the powdery mixture of Magaetit and up to 5 Seidebteproseatee varying amounts of therraoplas-tiecheai" material, eatable from polyvinyl chloride, Polyäthea or Polytetapeflnoxöthen, consists « 1 0 9 8 3 5/1 4 1 S ORIGINAL INSPECTED 5 · ¥ ®rfaiiren aur heration of a mooopoleran according to Aaapruoli 2, thereby bleoh on -eiaer or on or with eiiaam ßemieefe voh Magaeisli i see material
toroii a ümB ice fiiaa © iia Method p ^ 'ilj mc! aii £ clieooa Qifcio a® © i = öQ ©! ¹ \ 1 4 ,! 'BiMm? f ^ Slf 1t ai equilateral Oa f oit iQ @ IWtWHii ORIGINAL INSPECTED- AC 10. The method according to claim 5, characterized in that the not in direct contact with the Titan bleoh applied powder standing rope mechanically removed and then a mixture of the magnetite pulrera with thermoplastic or polycondensable materials applied and sintered according to the "known β η process" 11 · The method according to claim 9 »characterized in that that a mixture of magnetite powder and polycondensable or polymerizable substances contained in the Condense or polymerize heat, is applied. 12. Procedure for making a bipolar electrode according to claim 3 »daduroh characterized that a titanium-plated copper sheet on the titanium side coated according to claims 5 to 10 and the copper side is nickel-plated in a known manner 109835 / U19 ORIOiNAiINSPECJTED