EP0635587B1 - Electrode comprising an iron containing substrate and a lead containing coating - Google Patents

Electrode comprising an iron containing substrate and a lead containing coating Download PDF

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Publication number
EP0635587B1
EP0635587B1 EP94108425A EP94108425A EP0635587B1 EP 0635587 B1 EP0635587 B1 EP 0635587B1 EP 94108425 A EP94108425 A EP 94108425A EP 94108425 A EP94108425 A EP 94108425A EP 0635587 B1 EP0635587 B1 EP 0635587B1
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EP
European Patent Office
Prior art keywords
lead
electrode
coating
copper
weight
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EP94108425A
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German (de)
French (fr)
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EP0635587A1 (en
Inventor
David Dr. Sopher
Andreas Dr. Gieseler
Hartmut Dr. Hibst
Klaus Dr. Harth
Peter Dr. Jaeger
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BASF SE
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BASF SE
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/29—Coupling reactions
    • C25B3/295—Coupling reactions hydrodimerisation

Definitions

  • the present invention relates to an improved electrode, consisting essentially of an electrically conductive core Iron and an electrically conductive coating from essentially Lead.
  • the present invention also relates to methods of manufacture the electrode according to the invention, its use for reductive coupling of olefinic reactants and a improved process for the reductive coupling of olefinic Reaction partners.
  • ADN acrylonitrile to adiponitrile
  • US-A 3,193,481 describes US-A 3,193,482 and US-A 3,193,483 the electrochemical manufacture of ADN in a divided cell, with pure cathode Lead is used.
  • Organic Electrochemistry Edit. Baizer and Lund, Marcel Dekker, New York, 1984, 986, becomes analog Manufacture of ADN a lead cathode containing 7% by weight Antimony used.
  • DE-A 2,338,341 describes the use of pure lead cathodes in undivided electrochemical cells for the production of ADN.
  • the disadvantage of the electrodes mentioned above is that regardless of whether the cathodes are made of lead or another Material, such as cadmium, are built up the anodes and corrode cathodes during the reaction and thereby disturbing Produce degradation products that include for deposits on the electrodes being able to lead.
  • these deposits can the electrohydrodimerization of acrylonitrile to a decrease selectivity for adiponitrile and increased Lead to hydrogen formation. It is therefore important to avoid deposits, caused by electrode degradation, i.a. on the cathode surface, to prevent.
  • the object of the present invention was therefore an electrode with a cathode consisting of lead or lead alloys increased resistance to corrosion put.
  • adiponitrile more economical through electrohydrodimerization of acrylonitrile and be made more environmentally friendly.
  • an electrode consisting of an electrical conductive core of essentially iron and an electrical conductive, single layer coating of lead and 0.3 to 3.5 wt .-% copper and optionally other elements selected from the group silver, selenium, tellurium, bismuth and antimony, found.
  • the electrode according to the invention consists of an electrically conductive Core of essentially iron and an electrically conductive, single-layer coating of lead and 0.3 to 3.5% by weight Copper and optionally further elements selected from the Group of silver, selenium, tellurium, bismuth and antimony.
  • the design of the electrodes is also not critical, so that the specialist from the variety of common electrode types such as plane-parallel plates, pipes, nets and disks suitable electrode types can choose. It is preferred to choose plane-parallel ones Plates.
  • the electrically conductive coating consists of Lead and 0.3 to 3.5% by weight copper.
  • the coating can other elements such as silver, selenium, tellurium, bismuth and antimony in amounts up to 3.5% by weight, preferably from 0.5 to 2% by weight, particularly preferably from 0.8 to 1.5% by weight.
  • Prefers is a coating with the following according to the previous observations Composition: 96.5 to 99.5, preferably 98 to 99.5% by weight Lead, 0.3 to 3, preferably 0.5 to 2% by weight copper, 0 to 3, preferably 0 to 2% by weight of silver and / or bismuth and / or selenium and / or tellurium and / or antimony.
  • the electrically conductive coating can be made by the usual methods be applied. Application is particularly preferred by electroplating, i.e. electrolytically, and by physical Deposition process selected from the group consisting of Vapor deposition, sputtering ("sputtering", i.e. metal vapor deposition) or arc coating.
  • electroplating i.e. electrolytically, and by physical Deposition process selected from the group consisting of Vapor deposition, sputtering ("sputtering", i.e. metal vapor deposition) or arc coating.
  • an electroplating bath with an iron or Sheet steel as the cathode and a lead as the anode, being the two electrodes are advantageously arranged parallel to one another are (see “Modern Electroplating”).
  • the electrolyte solution usually contains what is to be separated Lead and, if desired, other elements in the form of their water-soluble Salts.
  • An aqueous silicic hydrofluoric acid, an aqueous fluoroborate or a C 1 -C 4 alkanesulfonic acid solution such as methane, ethane, propane or butanesulfonic acid solution, preferably methanesulfonic acid solution, is preferably used as the electrolyte solution.
  • the electrolyte solution is generally present essentially from lead fluoroborate.
  • the electrolytic solution still contains common auxiliaries such as fluoroboric acid, Boric acid and common organic additives such as a peptone, resorcinol or hydroquinone to achieve fine-grained, smooth precipitates.
  • lead fluoroborate is used in concentrations in the range from 5 to 500 g / l, preferably from 20 to 400 g / l, and copper in the form of its fluoroborate salt, oxide, hydride or Carbonates in concentrations ranging from 0.1 to 10, preferably from 0.5 to 10 g / l.
  • Fluoroboric acid is generally used in the range from 10 to 150, preferably from 15 to 90 g / l a.
  • Boric acid is usually used in the range from 5 to 50, preferably from 10 to 30 g / l.
  • Uses common organic additives one generally in amounts in the range of 0.1 to 5 g / l.
  • the other elements possible in addition to lead and copper such as silver, selenium, tellurium, bismuth and / or antimony expedient in the form of their fluoroborate salts, oxides, hydroxides or Carbonates in concentrations ranging from 0.1 to 10, preferably from 0.5 to 10 g / l.
  • lead is usually used in the form of its salt of methanesulfonic acid in amounts in the range from 10 to 200, preferably from 10 to 60 g / l and copper in the form of the corresponding C 1 -C 4 -alkanesulfonic acid salt, oxide, hydroxide or carbonate in amounts in the range from 0.1 to 20, preferably from 0.5 to 10 g / l.
  • the electrolyte solution also contains customary auxiliaries such as the corresponding C 1 -C 4 -alkanesulfonic acid, usually methanesulfonic acid, in an amount in the range from 20 to 150, preferably from 30 to 80 g / l, and surfactants, for example such based on alkylphenol ethoxylates such as Lutensol® AP 10 (BASF AG), in amounts in the range from 1 to 20, preferably from 5 to 15 g / l.
  • auxiliaries such as the corresponding C 1 -C 4 -alkanesulfonic acid, usually methanesulfonic acid, in an amount in the range from 20 to 150, preferably from 30 to 80 g / l
  • surfactants for example such based on alkylphenol ethoxylates such as Lutensol® AP 10 (BASF AG), in amounts in the range from 1 to 20, preferably from 5 to 15 g / l.
  • the electrode coating can contain the elements already listed above, such as silver, selenium, tellurium, bismuth and / or antimony, which are expediently in the form of their corresponding C 1 -C 4 -alkanesulfonic acid salts, oxides, hydroxides or carbonates in amounts in the range from 0.1 to 20, preferably from 0.5 to 10 g / l, to the electrolyte solution.
  • elements already listed above such as silver, selenium, tellurium, bismuth and / or antimony, which are expediently in the form of their corresponding C 1 -C 4 -alkanesulfonic acid salts, oxides, hydroxides or carbonates in amounts in the range from 0.1 to 20, preferably from 0.5 to 10 g / l, to the electrolyte solution.
  • a DC voltage of 0.5 to 20, preferably 1 to 10 volts is generally applied to the electrodes.
  • the current density during the electroplating is generally in the range from 1 to 200, preferably from 5 to 40 mA / cm 2 .
  • the duration of the electroplating depends on the chosen reaction parameters and the desired layer thickness of the coating from and is usually in the range of 0.5 to 10 hours. In general you choose the layer thickness in the range of 1 to 500, preferably from 20 to 200 ⁇ m.
  • the temperature during the electroplating is preferably chosen in the range from 10 to 70 ° C., the reaction is preferably carried out Room temperature through.
  • the selected pressure range is generally not critical, preferred one works at atmospheric pressure.
  • the pH value essentially depends on the electrolytes used and additives and is usually in the range from 0 to 2nd
  • pulse current techniques Pulsed current techniques
  • Another preferred embodiment is galvanic Deposition in a through an ion exchange membrane such as Cation or anion exchange membrane, preferably an anion exchange membrane, divided cell.
  • an ion exchange membrane such as Cation or anion exchange membrane, preferably an anion exchange membrane, divided cell. This procedure has the advantage that unwanted deposits are used further Elements, especially copper, on the anode are suppressed can.
  • any suitable one can be used as a galvanizing cell
  • the process parameters are in general with the identical above.
  • anion exchange membranes can be used as the anion exchange membrane such as Selemion® AMV (Asahi Glass), Neosepta® ACH 45T AM1, -AM2, -AM3 (Tokoyama Soda) or Aciplex® A 101, -102 Use (Asahi Chemical).
  • the production can of the electrodes according to the invention also by physical deposition processes such as vapor deposition, sputtering ("sputtering") or carry out an arc coating.
  • physical deposition processes such as vapor deposition, sputtering ("sputtering") or carry out an arc coating.
  • Cathode sputtering allows the layer thickness of the electrode coating in the range between 5 Angstroms and 100 ⁇ m. Furthermore, cathode sputtering allows simple and reproducible production of a multi-component layer, according to the previous knowledge, no limitation regarding the number of elements applied can be observed.
  • the microstructure of the electrode coating can be influenced by means of sputtering by varying the process gas pressure and / or by applying a negative bias (bias).
  • bias a process gas pressure in the range of 4 * 10 -3 to 8 * 10 -3 mbar leads to a very dense, fine-crystalline layer with high corrosion stability.
  • the coating material is generally applied in solid form as a so-called target to the cathode of a plasma system, then under reduced pressure, for example from 1 * 10 -4 to 1 mbar, preferably 5 * 10 -4 to 5 * 10 -2 mbar , atomized in a process gas atmosphere by applying a plasma and deposited on the substrate to be coated (anode) (see RFBhunshah et al., "Deposition Technologies for Films and Coatings", Noyes Publications, 1982).
  • at least one noble gas such as helium, neon or argon, preferably argon, is selected as the process gas.
  • the plasma usually consists of charged (ions and electrons) and neutral (partly radical) components of the process gas, which interact with each other via shock and radiation processes stand.
  • Various methodological methods can be used to produce the electrode coating Variants of cathode sputtering such as magnetron sputtering, DC and RF sputtering or bias sputtering and their combinations be applied.
  • Magnetron sputtering is in the Rule the target to be atomized in an external magnetic field, which concentrates the plasma in the area of the target and thus increasing the atomization rate.
  • DC or RF sputtering is generally used to excite the sputtering plasma by a direct voltage (DC) or by an alternating voltage (RF), for example with a frequency in the range of 10 kHz to 100 MHz, preferably 13.6 MHz.
  • Bias sputtering is usually the substrate to be coated with a in the Usually negative bias (bias) proves which in general during the coating for an intensive bombardment of the substrate leads with ions.
  • Suitable targets are, for example homogeneous alloy targets in a known manner can be produced by melting or powder metallurgical processes are, and inhomogeneous mosaic targets that are usually caused by Assembling smaller sections of different chemical Composition or by placing or sticking small ones disc-shaped pieces of material can be produced on homogeneous targets are.
  • homogeneous alloy targets in a known manner can be produced by melting or powder metallurgical processes are, and inhomogeneous mosaic targets that are usually caused by Assembling smaller sections of different chemical Composition or by placing or sticking small ones disc-shaped pieces of material can be produced on homogeneous targets are.
  • the desired layer thickness and the chemical composition and the microstructure of the electrode coating are essentially through the process gas pressure, the atomization performance, the sputtering mode, to influence the substrate temperature and the coating time.
  • the atomizing power is the power for excitation of the plasma is used, and is usually in the range from 50 W to 10 kW.
  • the substrate temperature is generally chosen in the range from Room temperature to 350, preferably from 150 to 250 ° C.
  • the coating time essentially depends on the desired Layer thickness. Typical coating rates for sputtering are usually in the range of 0.1 to 100 nm / s.
  • Another preferred embodiment is the production of the electrode coating by vapor deposition (see L. Holland, Vacuum Deposition of Thin Films, Chapman and Hay Ltd., 1970).
  • the coating material is expediently introduced in a manner known per se into a suitable evaporation source, such as electrically heated evaporator boats or electron beam evaporators.
  • the coating material is then evaporated under reduced pressure, usually in the range from 10 -7 to 10 -3 mbar, the desired coating being formed on the electrode introduced in the vacuum system.
  • the evaporation material can be used in the production of multi-component layers either in the appropriate composition a common source or simultaneously from different sources be evaporated.
  • Typical coating rates during evaporation are in general in the range from 10 nm / s to 10 ⁇ m / s.
  • that to be coated can be Substrate before or during the vapor deposition process an RF plasma or using a conventional ion gun Bombarded to the microstructure and the adhesion of the ions To improve layers. You can also see the microstructure and also affect the adhesion of the layers by heating the substrate.
  • the electrodes according to the invention can be used for reductive coupling of olefinic reactants.
  • olefinic reactants usually the olefinic reactants by electrohydrodimerization according to conventional reaction methods brought by being in an electrolytic cell with an anode and exposed to an electrode according to the invention as a cathode of electrolysis will.
  • R 1 R 2 C CR 3 X in which R 1 , R 2 and R 3 are the same or different hydrogen or C 1 -C 4 alkyl, such as methyl, ethyl, n-propyl , i-Propyl, n-butyl, i-butyl, sec-butyl or tert-butyl, and X is -CN, -CONR 1 R 2 or -COOR 1 .
  • Examples include olefinic nitriles such as acrylonitrile, methacrylonitrile, crotononitrile, 2-Methylenbutyronitril, 2-pentenenitrile, 2-Methylenvalerian Textrenitril or 2-Methylenhexanklarenitril, olefinic carboxylates such as acrylate, methyl or Ethylacryl Acidester olefinic carboxamides such as acrylamide, methacrylamide, N, N-dimethyl - or N, N-diethylacrylamide, particularly preferably acrylonitrile.
  • one provides with the help of the electrodes according to the invention adiponitrile Electrohydrodimerization from acrylonitrile.
  • the following information therefore refer to this procedure.
  • the type of electrolysis cell is based on previous observations uncritical, so that the specialist from the spectrum of commercially available Can choose electrolytic cells.
  • a preferred embodiment the undivided cell represents the electrolytic cell represents, especially plate stack cells or capillary gap cells to be favoured.
  • Such cells are, for example, in J. Electrochem. Soc. 131 (1984) 435c and J. Appl. Electrochemical. 2 (1972) 59 described in detail.
  • Known anodes can be used as the anode, preferably with undivided ones
  • Cells are usually made of materials with less Oxygen overvoltage, for example carbon steel, steel, Platinum, nickel, magnetite, lead, lead alloys or lead dioxide, a (see Hydrocarbon Processing (1981) 161).
  • the electrodes according to the invention are used as cathodes with a composition of the following type according to the previous ones Observations can preferably use: 96.5 to 100, preferably 98 to 99.5% by weight of lead, 0.3 to 3, preferably 0.5 up to 2% by weight copper, 0 to 3, preferably 0 to 2% by weight silver and / or bismuth and / or selenium and / or tellurium and / or antimony.
  • the electrolyte solution usually contains a conductive salt, in particular in the manufacture of adiponitrile, otherwise in usually propionitrile becomes the main product and with an increased one Hydrogen formation is to be expected.
  • a conductive salt in particular in the manufacture of adiponitrile, otherwise in usually propionitrile becomes the main product and with an increased one Hydrogen formation is to be expected.
  • the conducting salt in an amount in the range of 1 to 100 mmol / kg aqueous electrolyte solution, preferably from 5 to 50 mmol / kg.
  • Suitable conductive salts are: quaternary Ammonium compounds such as tetrabutylammonium salts, ethyltributylammonium salts, quaternary phosphonium salts and bisquaternaries Ammonium and phosphonium salts such as hexamethylene bis (dibutylethylammonium hydroxide) (see Hydrocarbon Processing 161 (1981); J. Electrochem. Soc. 131 (1984) 435c).
  • quaternary Ammonium compounds such as tetrabutylammonium salts, ethyltributylammonium salts, quaternary phosphonium salts and bisquaternaries Ammonium and phosphonium salts such as hexamethylene bis (dibutylethylammonium hydroxide) (see Hydrocarbon Processing 161 (1981); J. Electrochem. Soc. 131 (1984) 435c).
  • the electrolyte solution usually contains one Buffers such as hydrogen phosphate, hydrogen carbonate, preferably in the form their sodium salts, particularly preferably disodium hydrogen phosphate, in an amount ranging from 10 to 150, preferably from 30 to 100 g / kg aqueous electrolyte solution.
  • Buffers such as hydrogen phosphate, hydrogen carbonate, preferably in the form their sodium salts, particularly preferably disodium hydrogen phosphate, in an amount ranging from 10 to 150, preferably from 30 to 100 g / kg aqueous electrolyte solution.
  • the electrolyte solution preferably contains an anode corrosion inhibitor like the borates known for this purpose (see Hydrocarbon Processing (1981) 161), preferably disodium diborate and orthoboric acid, in an amount in the range of 5 to 50, preferred from 10 to 30 g / kg aqueous electrolyte solution.
  • anode corrosion inhibitor like the borates known for this purpose (see Hydrocarbon Processing (1981) 161), preferably disodium diborate and orthoboric acid, in an amount in the range of 5 to 50, preferred from 10 to 30 g / kg aqueous electrolyte solution.
  • the electrolyte solution preferably contains a complexing agent, to prevent the precipitation of iron and lead ions.
  • a complexing agent examples include ethylenediaminetetraacetate (“EDTA”), triethanolamine (“TEOA”), nitrilotriacetate, preferred EDTA in an amount ranging from 0 to 50, preferably 2 to 10 g / kg aqueous electrolyte solution, and / or TEOA in an amount in the range of 0 to 10, preferably 0.5 to 3 g / kg more aqueous Electrolyte solution.
  • Acrylonitrile is generally used in an amount in the range from 10 to 50, preferably from 20 to 30 wt .-%, based on the organic phase, a.
  • the reaction temperature is generally chosen in the range from 30 to 80, preferably from 50 to 60 ° C.
  • the pH essentially depends on the composition of the Electrolyte solution and is generally in the range of 6 to 10, preferably 7.5 to 9.
  • reaction pressure is not critical. It is usually chosen in the range from normal pressure to 10 bar.
  • the current density is generally chosen in the range from 1 to 40, preferably from 5 to 30 A / dm 2 .
  • the flow rate with continuous operation is usually in the range of 0.5 to 2 m / sec, preferably 0.8 to 1.5 m / sec.
  • the advantage of the electrode according to the invention is that Use as a cathode in the electrohydrodimerization of acrylonitrile to adiponitrile the corrosion of the cathodes is significantly less than when using solid lead or lead alloy electrodes, resulting in longer downtimes and less Amount of heavy metals.
  • the indicated corrosion rates of the electrodes were by means of atomic absorption spectroscopy (determination of the concentration on lead ions (cathode) released by corrosion and Iron ions (anode)) and by determining the weight loss of the electrodes after the end of the reaction.
  • the specified selectivities were determined using a gas chromatograph determined.
  • a round steel disc (diameter 20 mm) was used as the cathode used, which degreased as usual before the galvanic coating and was stained.
  • a lead strip also served as the anode the same dimensions as the cathode.
  • the electrodes were mounted parallel to each other in a tank. The reaction mixture in the bathroom was moved by mechanical stirring, the bath temperature was 25 ° C.
  • the coating bath (1 l) had the following composition: free fluoroboric acid 20 g / l Boric acid 30 g / l Lead fluoroborate 90 g / l Peptone 0.5 g / l water to 1 l
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally contained 2.6 g / l copper fluoroborate.
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally contained 0.7 g / l copper fluoroborate.
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally contained 1.6 g / l copper fluoroborate.
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally contained 5.6 g / l copper fluoroborate.
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally 1.25 g / l copper fluoroborate and Contained 0.5 g / l bismuth nitrate.
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally 1.5 g / l copper fluoroborate and Contained 0.65 g / l tellurium dioxide.
  • the layer thickness was 50 ⁇ m.
  • Example 2 The procedure was as in Example 1, with the difference that the coating bath additionally 2.7 g / l copper fluoroborate and Contained 0.15 g / l selenium dioxide.
  • the layer thickness was 50 ⁇ m.
  • the cathode consisted of a pencil strip of the same dimensions.
  • the coating bath (10 1) had the following composition: free methanesulfonic acid 32 g / l Lead methanesulfonate 70 g / l Copper methanesulfonate 5.2 g / l Lutensol® AP 10 10 g / l
  • the layer thickness was 60 ⁇ m.
  • the coating contained 1% by weight copper.
  • a round steel electrode with a diameter of 20 mm was placed in a cathode sputtering system. Parallel to the steel substrate, a round mosaic target (diameter 150 mm) consisting of lead with copper discs (diameter 2 mm) was used at a distance of 60 mm. The area occupancy rate is shown in Table 1. The system was evacuated to a pressure of 10 -6 mbar using a two-stage pump system.
  • the substrate was heated to a temperature of 200 ° C. Then argon was admitted to a pressure of 9 x 10 -3 mbar.
  • the substrate was subjected to a sputter etching treatment for 1 min by applying an RF voltage with a power of 500 W to the substrate holder. After completion of the sputter etching treatment, the Ar pressure was set to 5 x 10 -3 mbar.
  • An atomizing plasma was ignited by applying a DC voltage to the target (power 1000 W) and an RF voltage to the substrate holder (power 200 W) and a (Pb-Cu) layer with a thickness of 10 ⁇ m was deposited on the stainless steel substrate .
  • the Cu content of the electrodes produced in this way is shown in Table 1. Area coverage of the Cu chips [%] Cu content of the electrode coating [% by weight] a 0 0 b 0.43 0.3 c 0.86 0.8 d 1.7 1.2 e 3.4 2.4 f 4.2 3.0 G 18th 13.0
  • the electrolytic solution was pumped through the electrolytic cell. From there it came into a separation vessel, where the formed Adiponitrile as an organic phase. Then was the aqueous electrolyte is pumped back into the electrolytic cell.
  • the organic phase consisted of:
  • the two phases were pumped around equilibrated so that acrylonitrile is dissolved in the aqueous phase was (about 2 wt .-%).
  • the remaining components were distributed according to their distributional equilibrium between the two Phases.
  • the conductive salt and approx. 4 wt .-% water in the organic phase so that the acrylonitrile concentration was about 26% by volume in the organic phase.
  • the electrolysis was operated continuously for 90 hours. After The massive lead cathode showed a corrosion rate of 90 hours of 0.35 mm / year (0.2 mg / Ah). The selectivity for adiponitrile was 90.3%.
  • the electrolysis was operated continuously for 90 hours. After The corrosion rate of the lead coating was 90 h of 0.25 mm / year (0.14 mg / Ah), the selectivity for adiponitrile was 90.4%.
  • the electrolysis was operated continuously for 200 hours. After A corrosion rate of 0.05 mm / year resulted for 200 h (0.03 mg / Ah), the selectivity was 90.9%.
  • the electrolysis was operated continuously for 209 hours. After The corrosion rate of the lead / copper cathode was 209 h of 0.16 mm / year (0.09 mg / Ah), the selectivity was 91.4%.
  • the electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.07 mm / year (0.04 mg / Ah), the selectivity was 90.4%.
  • the electrolysis was operated continuously for 90 hours. After The corrosion rate of the lead / copper cathode was 90 h of 0.05 mm / year (0.03 mg / Ah), the selectivity was 88.8%.
  • the electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.08 mm / year (0.045 mg / Ah), the selectivity was 90.0%.
  • the electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.09 mm / year (0.05 mg / Ah), the selectivity was 90.9%.
  • the electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.05 mm / year (0.03 mg / Ah), the selectivity was 90.9%.
  • the aqueous phase was pumped through the electrolytic cell.
  • the adiponitrile formed separated as organic in a separating vessel Phase. Then the aqueous electrolyte was restored returned to the electrolytic cell.
  • the organic phase consisted of: 30 vol% acrylonitrile and 70 vol% adiponitrile.
  • the two phases were pumped around equilibrated so that acrylonitrile is dissolved in the aqueous phase was (about 2 wt .-%).
  • the remaining components were distributed according to their distributional equilibrium between the two Phases.
  • the conductive salt and approx. 4 wt .-% water in the organic phase so that the acrylonitrile concentration was about 24% by volume in the organic phase.
  • the alloy electrode After 650 h, the alloy electrode showed a corrosion rate of 0.05 mm / year (0.03 mg / Ah), the selectivity for adiponitrile was 91.4%.
  • the bathroom had the following composition: Catholyte free methanesulfonic acid 48 g / l Lead methanesulfonate 64 g / l Copper methanesulfonate 5 g / l Lutensol® AP 10 10 g / l Anolyte free methanesulfonic acid 42 g / l Lead methanesulfonate 95 g / l
  • Electroplating was carried out for 2 hours at a current density of 12.5 mA / cm 2 .
  • the layer thickness was 60 ⁇ m.
  • the alloy contained 0.8% by weight of copper.
  • the electrolysis was operated continuously for 132 hours. After The lead coating showed a corrosion rate of 132 h of 0.14 mm / year (0.08 mg / Ah), the selectivity for adiponitrile was 90.6%.
  • the electrolysis was operated continuously for 90 hours. After The corrosion rate of the lead / copper cathode was 90 h of 0.08 mm / year (0.045 mg / Ah), the selectivity for adiponitrile was 90.3%.

Description

Die vorliegende Erfindung betrifft eine verbesserte Elektrode, bestehend aus einem elektrisch leitfähigen Kern aus im wesentlichen Eisen und einem elektrisch leitfähigen Überzug aus im wesentlichen Blei.The present invention relates to an improved electrode, consisting essentially of an electrically conductive core Iron and an electrically conductive coating from essentially Lead.

Außerdem betrifft die vorliegende Erfindung Verfahren zur Herstellung der erfindungsgemaßen Elektrode, deren Verwendung zur reduktiven Kupplung von olefinischen Reaktionspartnern sowie ein verbessertes Verfahren zur reduktiven Kupplung von olefinischen Reaktionspartnern.The present invention also relates to methods of manufacture the electrode according to the invention, its use for reductive coupling of olefinic reactants and a improved process for the reductive coupling of olefinic Reaction partners.

Die Verwendung von Bleikathoden in elektrochemischen Prozessen, z.B. bei der Elektrohydrodimerisierung von Acrylnitril zu Adipodinitril ("ADN"), ist bekannt. So beschreiben die US-A 3,193,481, US-A 3,193,482 und US-A 3,193,483 die elektrochemische Herstellung von ADN in einer geteilten Zelle, wobei als Kathode reines Blei eingesetzt wird. In Organic Electrochemistry, Edit. Baizer und Lund, Marcel Dekker, New York, 1984, 986, wird zur analogen Herstellung von ADN eine Kathode aus Blei, enthaltend 7 Gew.-% Antimon verwendet.The use of lead cathodes in electrochemical processes, e.g. in the electrohydrodimerization of acrylonitrile to adiponitrile ("ADN") is known. For example, US-A 3,193,481 describes US-A 3,193,482 and US-A 3,193,483 the electrochemical manufacture of ADN in a divided cell, with pure cathode Lead is used. In Organic Electrochemistry, Edit. Baizer and Lund, Marcel Dekker, New York, 1984, 986, becomes analog Manufacture of ADN a lead cathode containing 7% by weight Antimony used.

Die DE-A 2,338,341 beschreibt den Einsatz von reinen Bleikathoden in ungeteilten elektrochemischen Zellen zur Herstellung von ADN.DE-A 2,338,341 describes the use of pure lead cathodes in undivided electrochemical cells for the production of ADN.

Der Nachteil der vorstehend genannten Elektroden besteht darin, daß, unabhängig davon, ob die Kathoden aus Blei oder einem anderen Material, beispielsweise Cadmium, aufgebaut sind, die Anoden und Kathoden während der Reaktion korrodieren und dabei störende Abbauprodukte produzieren, die u.a. zu Ablagerungen auf den Elektroden führen können. Insbesondere können diese Ablagerungen bei der Elektrohydrodimerisierung von Acrylnitril zu einer Abnahme der Selektivität hinsichtlich Adipodinitril und zu einer vermehrten Wasserstoffbildung führen. Es ist daher wichtig, Ablagerungen, hervorgerufen durch Elektrodenabbau, u.a. auf der Kathodenoberfläche, zu verhindern.The disadvantage of the electrodes mentioned above is that that regardless of whether the cathodes are made of lead or another Material, such as cadmium, are built up the anodes and corrode cathodes during the reaction and thereby disturbing Produce degradation products that include for deposits on the electrodes being able to lead. In particular, these deposits can the electrohydrodimerization of acrylonitrile to a decrease selectivity for adiponitrile and increased Lead to hydrogen formation. It is therefore important to avoid deposits, caused by electrode degradation, i.a. on the cathode surface, to prevent.

Eine Möglichkeit solche Ablagerungen zu verhindern, beschreibt die US-A 3,898,140, in deren Verfahren Ethylendiamintetraacetat ("EDTA") als Einschlußmittel eingesetzt wird. Die Verwendung von Trialkylolaminen mit dem gleichen Effekt beschreibt die GB-A 1,501,313. One way to prevent such deposits is described US-A 3,898,140, in the process of ethylenediaminetetraacetate ("EDTA") is used as an inclusion agent. The use of Trialkylolamines with the same effect are described in GB-A 1,501,313.

Ein Nachteil solcher Einschlußmittel ist allerdings, daß die Bleikathode zu schnell verbraucht wird (JP-A 84/59888). Um diesen Nachteil zu umgehen, wurde vorgeschlagen, auf den Einsatz von Einschlußmitteln zu verzichten, indem man statt dessen den Elektrolyten kontinuierlich von Elektrodenabbauprodukten dadurch befreit, daß man ihn über eine Säule, enthaltend ein chelathaltiges Harz, leitet.A disadvantage of such inclusion agents is, however, that the Lead cathode is consumed too quickly (JP-A 84/59888). To this To avoid disadvantage, it was suggested to use To avoid inclusion agents by using the electrolyte instead continuously freed from electrode degradation products by that it was placed over a column containing a chelate Harz, conducts.

Eine Weiterentwicklung bei der Herstellung von ADN in einer ungeteilten elektrochemischen Zelle ist in der EP-A 270 390 beschrieben. In diesem Dokument wird als Kathode eine Bleilegierung beansprucht, enthaltend 1 Gew.-% oder weniger an Kupfer und Tellur. Nachteilig hierbei ist, daß die Elektrohydrodimerisierung in Gegenwart einer bestimmten Menge an Ethyltributylammoniumsalz erfolgen muß. Selbst unter diesen Bedingungen ist die Korrosionsrate noch zu hoch.A further development in the production of ADN in an undivided electrochemical cell is described in EP-A 270 390. In this document, a lead alloy is claimed as the cathode, containing 1% by weight or less of copper and tellurium. The disadvantage here is that the electrohydrodimerization in the presence a certain amount of ethyltributylammonium salt got to. Even under these conditions, the rate of corrosion still too high.

Aufgabe der vorliegenden Erfindung war es daher, eine Elektrode mit einer gegenüber aus Blei oder Bleilegierungen bestehenden Kathode erhöhten Beständigkeit gegen Korrosion zur Verfügung zu stellen. Insbesondere sollte hierdurch die Herstellung von Adipodinitril durch Elektrohydrodimerisierung von Acrylnitril wirtschaftlicher und umweltschonender gemacht werden.The object of the present invention was therefore an electrode with a cathode consisting of lead or lead alloys increased resistance to corrosion put. In particular, the production of adiponitrile more economical through electrohydrodimerization of acrylonitrile and be made more environmentally friendly.

Demgemäß wurde eine Elektrode, bestehend aus einem elektrisch leitfähigen Kern aus im wesentlichen Eisen und einem elektrisch leitfähigen, einschichtigen Überzug aus Blei und 0,3 bis 3,5 Gew.-% Kupfer und gegebenenfalls weiteren Elementen, ausgewählt aus der Gruppe Silber, Selen, Tellur, Bismut und Antimon, gefunden.Accordingly, an electrode consisting of an electrical conductive core of essentially iron and an electrical conductive, single layer coating of lead and 0.3 to 3.5 wt .-% copper and optionally other elements selected from the group silver, selenium, tellurium, bismuth and antimony, found.

Ferner wurden Verfahren zur Herstellung dieser Elektrode, die Verwendung der erfindungsgemäßen Elektrode zur reduktiven Kupplung von olefinischen Reaktionspartnern sowie ein verbessertes Verfahren zur reduktiven Kupplung von olefinischen Reaktionspartnern gefunden.Furthermore, methods of manufacturing this electrode, which Use of the electrode according to the invention for reductive coupling of olefinic reactants as well as an improved Process for the reductive coupling of olefinic reactants found.

Die erfindungsgemäße Elektrode besteht aus einem elektrisch leitfähigen Kern aus im wesentlichen Eisen und einem elektrisch leitfähigen, einschichtigen Überzug aus Blei und 0,3 bis 3,5 Gew.-% Kupfer und gegebenenfalls weiteren ELementen, ausgewählt aus der Gruppe Silber, Selen, Tellur, Bismut und Antimon.The electrode according to the invention consists of an electrically conductive Core of essentially iron and an electrically conductive, single-layer coating of lead and 0.3 to 3.5% by weight Copper and optionally further elements selected from the Group of silver, selenium, tellurium, bismuth and antimony.

Die Wahl des verwendeten Eisens ist nach den bisherigen Beobachtungen unkritisch. Für eine Reihe von Prozessen kann es jedoch von Vorteil sein, besonders korrosionsbeständige Eisenstähle einzusetzen. The choice of iron used is based on previous observations not critical. However, for a number of processes it can be of advantage to use particularly corrosion-resistant iron steels.

Die Gestaltung der Elektroden ist ebenfalls unkritisch, so daß der Fachmann aus der Vielzahl der gängigen Elektrodenarten wie planparallele Platten, Rohre, Netze und Scheiben geeignete Elektrodenarten auswählen kann. Bevorzugt wählt man planparallele Platten.The design of the electrodes is also not critical, so that the specialist from the variety of common electrode types such as plane-parallel plates, pipes, nets and disks suitable electrode types can choose. It is preferred to choose plane-parallel ones Plates.

Der elektrisch leitfähige Überzug besteht erfindungsgemäß aus Blei und 0,3 bis 3,5 Gew.-% Kupfer. Neben Blei kann der Überzug noch weitere Elemente wie Silber, Selen, Tellur, Bismut und Antimon in Mengen bis zu 3,5 Gew.-%, bevorzugt von 0,5 bis 2 Gew.-%, besonders bevorzugt von 0,8 bis 1,5 Gew.-%, enthalten. Bevorzugt ist nach den bisherigen Beobachtungen ein Überzug mit folgender Zusammensetzung: 96,5 bis 99,5, vorzugsweise 98 bis 99,5 Gew.-% Blei, 0,3 bis 3, vorzugsweise 0,5 bis 2 Gew.-% Kupfer, 0 bis 3, vorzugsweise 0 bis 2 Gew.-% Silber und/oder Bismut und/oder Selen und/oder Tellur und/oder Antimon.According to the invention, the electrically conductive coating consists of Lead and 0.3 to 3.5% by weight copper. In addition to lead, the coating can other elements such as silver, selenium, tellurium, bismuth and antimony in amounts up to 3.5% by weight, preferably from 0.5 to 2% by weight, particularly preferably from 0.8 to 1.5% by weight. Prefers is a coating with the following according to the previous observations Composition: 96.5 to 99.5, preferably 98 to 99.5% by weight Lead, 0.3 to 3, preferably 0.5 to 2% by weight copper, 0 to 3, preferably 0 to 2% by weight of silver and / or bismuth and / or selenium and / or tellurium and / or antimony.

Der elektrisch leitfähige Überzug kann nach den üblichen Verfahren aufgebracht werden. Besonders bevorzugt ist das Aufbringen durch Galvanisieren, d.h. elektrolytisch, und durch physikalische Depositionsverfahren, ausgewählt aus der Gruppe bestehend aus Aufdampfen, Kathodenzerstäuben ("Sputtern", d.h. Metallbedampfung) oder Lichtbogenbeschichtung.The electrically conductive coating can be made by the usual methods be applied. Application is particularly preferred by electroplating, i.e. electrolytically, and by physical Deposition process selected from the group consisting of Vapor deposition, sputtering ("sputtering", i.e. metal vapor deposition) or arc coating.

Der Vorgang des Galvanisierens ist hinreichend bekannt, z.B. aus "Modern Electroplating" (Editor: Lowenheim, J.Wiley, New York, 1974), so daß sich nähere Ausführungen hierzu erübrigen. Des weiteren ist nach den bisherigen Beobachtungen die Art der Galvanisierbäder von untergeordneter Bedeutung.The process of electroplating is well known, e.g. out "Modern Electroplating" (Editor: Lowenheim, J.Wiley, New York, 1974), so there is no need for further explanations. Furthermore is the type of electroplating baths according to the previous observations of minor importance.

Bevorzugt verwendet man ein Galvanisierbad mit einem Eisen- oder Stahlblech als Kathode und einem Bleistreifen als Anode, wobei die beiden Elektroden zweckmäßig parallel zueinander angeordnet sind (s. "Modern Electroplating").It is preferred to use an electroplating bath with an iron or Sheet steel as the cathode and a lead as the anode, being the two electrodes are advantageously arranged parallel to one another are (see "Modern Electroplating").

Die Elektrolytlösung enthält üblicherweise das abzuscheidende Blei sowie gewünschtenfalls weitere Elemente in Form ihrer wasserlöslichen Salze.The electrolyte solution usually contains what is to be separated Lead and, if desired, other elements in the form of their water-soluble Salts.

Bevorzugt verwendet man als Elektrolytlösung eine wäßrige Kieselfluorwasserstoffsäure, eine wäßrige Fluoroborat- oder eine C1-C4-Alkansulfonsäure-Lösung wie Methan-, Ethan-, Propan- oder Butansulfonsäure-Lösung, bevorzugt Methansulfonsäure-Lösung.An aqueous silicic hydrofluoric acid, an aqueous fluoroborate or a C 1 -C 4 alkanesulfonic acid solution such as methane, ethane, propane or butanesulfonic acid solution, preferably methanesulfonic acid solution, is preferably used as the electrolyte solution.

Bei einem Fluoroboratbad besteht im allgemeinen die Elektrolytlösung im wesentlichen aus Bleifluoroborat. Zweckmäßig enthält die Elektrolytlösung noch übliche Hilfsstoffe wie Fluoroborsäure, Borsäure und übliche organische Zusätze wie ein Pepton, Resorcin oder Hydrochinon zur Erzielung feinkörniger glatter Niederschläge.In the case of a fluoroborate bath, the electrolyte solution is generally present essentially from lead fluoroborate. Appropriately contains the electrolytic solution still contains common auxiliaries such as fluoroboric acid, Boric acid and common organic additives such as a peptone, resorcinol or hydroquinone to achieve fine-grained, smooth precipitates.

Die folgenden Konzentrationsangaben beziehen sich, soweit nicht anders vermerkt, auf 1 1 Elektrolytlösung.The following concentration details relate, if not otherwise noted, to 1 1 electrolyte solution.

Üblicherweise setzt man dabei Bleifluoroborat in Konzentrationen im Bereich von 5 bis 500 g/l, vorzugsweise von 20 bis 400 g/l, und Kupfer in Form seines Fluorborat-Salzes, Oxids, Hydrids oder Carbonats in Konzentrationen im Bereich von 0,1 bis 10, vorzugsweise von 0,5 bis 10 g/l, ein. Fluoroborsäure setzt man im allgemeinen im Bereich von 10 bis 150, vorzugsweise von 15 bis 90 g/l ein. Borsäure verwendet man in der Regel im Bereich von 5 bis 50, vorzugsweise von 10 bis 30 g/l. Übliche organische Zusätze setzt man im allgemeinen in Mengen im Bereich von 0,1 bis 5 g/l ein.Usually lead fluoroborate is used in concentrations in the range from 5 to 500 g / l, preferably from 20 to 400 g / l, and copper in the form of its fluoroborate salt, oxide, hydride or Carbonates in concentrations ranging from 0.1 to 10, preferably from 0.5 to 10 g / l. Fluoroboric acid is generally used in the range from 10 to 150, preferably from 15 to 90 g / l a. Boric acid is usually used in the range from 5 to 50, preferably from 10 to 30 g / l. Uses common organic additives one generally in amounts in the range of 0.1 to 5 g / l.

Die zusätzlich zum Blei und Kupfer möglichen weiteren Elemente wie Silber, Selen, Tellur, Bismut und/oder Antimon, setzt man zweckmäßig in Form ihrer Fluoroborat-Salze, Oxide, Hydroxide oder Carbonate in Konzentrationen im Bereich von 0,1 bis 10, vorzugsweise von 0,5 bis 10 g/l, ein.The other elements possible in addition to lead and copper such as silver, selenium, tellurium, bismuth and / or antimony expedient in the form of their fluoroborate salts, oxides, hydroxides or Carbonates in concentrations ranging from 0.1 to 10, preferably from 0.5 to 10 g / l.

Im Falle eines C1-C4-Alkansulfonsäurebades, insbesondere eines Methansulfonsäurebades, setzt man Blei üblicherweise in Form seines Salzes der Methansulfonsäure in Mengen im Bereich von 10 bis 200, vorzugsweise von 10 bis 60 g/l und Kupfer in Form des entsprechenden C1-C4-Alkansulfonsäure-Salzes, Oxids, Hydroxids oder Carbonats in Mengen im Bereich von 0,1 bis 20, vorzugsweise von 0,5 bis 10 g/l ein. Analog zum Fluoroboratbad enthält die Elektrolytlösung noch übliche Hilfsstoffe wie die entsprechende C1-C4-Alkansulfonsäure, in der Regel Methansulfonsäure, in einer Menge im Bereich von 20 bis 150, vorzugsweise von 30 bis 80 g/l, und Tenside, beispielsweise ein solches auf Basis von Alkylphenolethoxylaten wie Lutensol® AP 10 (BASF AG), in Mengen im Bereich von 1 bis 20, vorzugsweise von 5 bis 15 g/l. Zusätzlich zum Blei und Kupfer kann der Elektrodenüberzug die weiter oben bereits aufgeführten Elemente wie Silber, Selen, Tellur, Bismut und/oder Antimon enthalten, die man zweckmäßig in Form ihrer entsprechenden C1-C4-Alkansulfonsäure-Salze, Oxide, Hydroxide oder Carbonate in Mengen im Bereich von 0,1 bis 20, vorzugsweise von 0,5 bis 10 g/l, der Elektrolytlösung zusetzt.In the case of a C 1 -C 4 alkanesulfonic acid bath, in particular a methanesulfonic acid bath, lead is usually used in the form of its salt of methanesulfonic acid in amounts in the range from 10 to 200, preferably from 10 to 60 g / l and copper in the form of the corresponding C 1 -C 4 -alkanesulfonic acid salt, oxide, hydroxide or carbonate in amounts in the range from 0.1 to 20, preferably from 0.5 to 10 g / l. Analogous to the fluoroborate bath, the electrolyte solution also contains customary auxiliaries such as the corresponding C 1 -C 4 -alkanesulfonic acid, usually methanesulfonic acid, in an amount in the range from 20 to 150, preferably from 30 to 80 g / l, and surfactants, for example such based on alkylphenol ethoxylates such as Lutensol® AP 10 (BASF AG), in amounts in the range from 1 to 20, preferably from 5 to 15 g / l. In addition to lead and copper, the electrode coating can contain the elements already listed above, such as silver, selenium, tellurium, bismuth and / or antimony, which are expediently in the form of their corresponding C 1 -C 4 -alkanesulfonic acid salts, oxides, hydroxides or carbonates in amounts in the range from 0.1 to 20, preferably from 0.5 to 10 g / l, to the electrolyte solution.

Beim Galvanisieren legt man in der Regel an die Elektroden eine Gleichspannung von 0,5 bis 20, bevorzugt von 1 bis 10 Volt an. Die Stromdichte während des Galvanisierens liegt in der Regel im Bereich von 1 bis 200, vorzugsweise von 5 bis 40 mA/cm2. When electroplating, a DC voltage of 0.5 to 20, preferably 1 to 10 volts is generally applied to the electrodes. The current density during the electroplating is generally in the range from 1 to 200, preferably from 5 to 40 mA / cm 2 .

Die Dauer des Galvanisierens hängt von den gewählten Reaktionsparametern und der gewünschten Schichtdicke des Überzugs ab und liegt üblicherweise im Bereich von 0,5 bis 10 h. Im allgemeinen wählt man die Schichtdicke im Bereich von 1 bis 500, vorzugsweise von 20 bis 200 µm.The duration of the electroplating depends on the chosen reaction parameters and the desired layer thickness of the coating from and is usually in the range of 0.5 to 10 hours. In general you choose the layer thickness in the range of 1 to 500, preferably from 20 to 200 µm.

Die Temperatur während des Galvanisierens wählt man vorzugsweise im Bereich von 10 bis 70°C, bevorzugt führt man die Reaktion bei Raumtemperatur durch.The temperature during the electroplating is preferably chosen in the range from 10 to 70 ° C., the reaction is preferably carried out Room temperature through.

Der gewählte Druckbereich ist im allgemeinen unkritisch, bevorzugt arbeitet man bei Atmosphärendruck.The selected pressure range is generally not critical, preferred one works at atmospheric pressure.

Der pH-Wert hängt im wesentlichen von den eingesetzten Elektrolyten und Zusätzen ab und liegt in der Regel im Bereich von 0 bis 2.The pH value essentially depends on the electrolytes used and additives and is usually in the range from 0 to 2nd

Anstelle einer Gleichspannung kann man auch Pulsstromtechniken (pulsed current techniques) verwenden (s. J.-C. Puippe, Pulse-Plating, E. Lenze Verlag, Saulgau, 1990).Instead of a DC voltage, you can also use pulse current techniques (pulsed current techniques) use (see J.-C. Puippe, Pulse-Plating, E. Lenze Verlag, Saulgau, 1990).

Eine weitere bevorzugte Ausführungsform besteht in der galvanischen Abscheidung in einer durch eine Ionenaustauschermembran wie Kationen- oder Anionenaustauschermembran, vorzugsweise eine Anionenaustauschermembran, geteilten Zelle. Diese Verfahrensweise hat den Vorteil, daß unerwünschte Abscheidungen weiterer eingesetzter Elemente, insbesondere von Kupfer, auf der Anode unterdrückt werden können.Another preferred embodiment is galvanic Deposition in a through an ion exchange membrane such as Cation or anion exchange membrane, preferably an anion exchange membrane, divided cell. This procedure has the advantage that unwanted deposits are used further Elements, especially copper, on the anode are suppressed can.

Als Galvanisierzelle kann man prinzipiell jede hierfür geeignete Form verwenden, insbesondere die weiter oben genannten Galvanisierzellen. Die Verfahrensparameter sind im allgemeinen mit den oben genannten identisch.In principle, any suitable one can be used as a galvanizing cell Use the mold, especially the plating cells mentioned above. The process parameters are in general with the identical above.

Als Anionenaustauschermembran kann man handelsübliche Anionenaustauschermembranen wie Selemion® AMV (Asahi Glass), Neosepta® ACH 45T AM1, -AM2, -AM3 (Tokoyama Soda) oder Aciplex® A 101, -102 (Asahi Chemical) einsetzen.Commercial anion exchange membranes can be used as the anion exchange membrane such as Selemion® AMV (Asahi Glass), Neosepta® ACH 45T AM1, -AM2, -AM3 (Tokoyama Soda) or Aciplex® A 101, -102 Use (Asahi Chemical).

Als weitere bevorzugte Ausführungsform kann man die Herstellung der erfindungsgemäßen Elektroden auch durch physikalische Depositionsverfahren wie Aufdampfen, Kathodenzerstäuben ("Sputtern") oder Lichtbogenbeschichtung vornehmen.As a further preferred embodiment, the production can of the electrodes according to the invention also by physical deposition processes such as vapor deposition, sputtering ("sputtering") or carry out an arc coating.

Die Kathodenzerstäubung erlaubt es, die Schichtdicke des Elektrodenüberzugs im Bereich zwischen 5 Angström und 100 µm einzustellen. Des weiteren gestattet die Kathodenzerstäubung die einfache und reproduzierbare Herstellung einer mehrkomponentigen Schicht, wobei nach der bisherigen Erkenntnis keine Begrenzung hinsichtlich der Anzahl der aufgebrachten Elemente zu beobachten ist.Cathode sputtering allows the layer thickness of the electrode coating in the range between 5 Angstroms and 100 µm. Furthermore, cathode sputtering allows simple and reproducible production of a multi-component layer, according to the previous knowledge, no limitation regarding the number of elements applied can be observed.

Ferner kann man mittels Kathodenzerstäubung die Mikrostruktur der Elektrodenbeschichtung durch Variation des Prozeßgasdrucks und/ oder durch Anlegen einer negativen Vorspannung (Bias) beeinflussen. So führt beispielsweise ein Prozeßgasdruck im Bereich von 4*10-3 bis 8*10-3 mbar zu einer sehr dichten, feinkristallinen Schicht mit einer hohen Korrosionsstabilität.Furthermore, the microstructure of the electrode coating can be influenced by means of sputtering by varying the process gas pressure and / or by applying a negative bias (bias). For example, a process gas pressure in the range of 4 * 10 -3 to 8 * 10 -3 mbar leads to a very dense, fine-crystalline layer with high corrosion stability.

Und das Anlegen einer negativen Vorspannung während der Beschichtung bewirkt im allgemeinen einen intensiven Ionenbeschuß des Substrats, was in der Regel zu einer sehr dichten Schicht sowie zu einer innigen Verzahnung der aufgebrachten Schicht mit dem Substrat führt.And applying a negative bias during coating causes an intensive ion bombardment of the Substrate, which usually results in a very dense layer as well for an intimate interlocking of the applied layer with the Leads substrate.

Bei der Kathodenzerstäubung wird im allgemeinen das Beschichtungsmaterial in fester Form als sogenanntes Target auf die Kathode eines Plasmasystems aufgebracht, dann unter vermindertem Druck, beispielsweise von 1*10-4 bis 1 mbar, vorzugsweise 5*10-4 bis 5*10-2 mbar, in einer Prozeßgasatmosphäre durch Anlegen eines Plasmas zerstäubt und auf dem zu beschichtenden Substrat (Anode) abgeschieden (s. R.F.Bhunshah et al., "Deposition Technologies for Films and Coatings", Noyes Publications, 1982). Als Prozeßgas wählt man im allgemeinen mindestens ein Edelgas wie Helium, Neon oder Argon, bevorzugt Argon.In cathode sputtering, the coating material is generally applied in solid form as a so-called target to the cathode of a plasma system, then under reduced pressure, for example from 1 * 10 -4 to 1 mbar, preferably 5 * 10 -4 to 5 * 10 -2 mbar , atomized in a process gas atmosphere by applying a plasma and deposited on the substrate to be coated (anode) (see RFBhunshah et al., "Deposition Technologies for Films and Coatings", Noyes Publications, 1982). In general, at least one noble gas such as helium, neon or argon, preferably argon, is selected as the process gas.

Das Plasma besteht in der Regel aus geladenen (Ionen und Elektronen) und neutralen (zum Teil radikalen) Bestandteilen des Prozeßgases, die über Stoß- und Strahlungsprozesse miteinander in Wechselwirkung stehen.The plasma usually consists of charged (ions and electrons) and neutral (partly radical) components of the process gas, which interact with each other via shock and radiation processes stand.

Zur Herstellung des Elektrodenüberzugs können verschiedene methodische Varianten der Kathodenzerstäubung wie Magnetron-Sputtern, DC- und RF- Sputtern oder Bias-Sputtern sowie deren Kombinationen angewendet werden. Beim Magnetron-Sputtern befindet sich in der Regel das zu zerstäubende Target in einem äußeren Magnetfeld, welches das Plasma in den Bereich des Targets konzentriert und damit eine Erhöhung der Zerstäubungsrate bewirkt. Beim DC- bzw. RF-Sputtern erfolgt im allgemeinen die Anregung des Zerstäubungsplasmas durch eine Gleichspannung (DC) oder durch eine Wechselspannung (RF), beispielsweise mit einer Frequenz im Bereich von 10 kHz bis 100 MHz, vorzugsweise 13,6 MHz. Beim Bias-Sputtern wird üblicherweise das zu beschichtende Substrat mit einer in der Regel negativen Vorspannung (Bias) belegt, welche im allgemeinen während der Beschichtung zu einem intensiven Beschuß des Substrats mit Ionen führt.Various methodological methods can be used to produce the electrode coating Variants of cathode sputtering such as magnetron sputtering, DC and RF sputtering or bias sputtering and their combinations be applied. Magnetron sputtering is in the Rule the target to be atomized in an external magnetic field, which concentrates the plasma in the area of the target and thus increasing the atomization rate. With the DC or RF sputtering is generally used to excite the sputtering plasma by a direct voltage (DC) or by an alternating voltage (RF), for example with a frequency in the range of 10 kHz to 100 MHz, preferably 13.6 MHz. Bias sputtering is usually the substrate to be coated with a in the Usually negative bias (bias) proves which in general during the coating for an intensive bombardment of the substrate leads with ions.

Zur Herstellung der Elektrodenüberzüge zerstäubt man im allgemeinen ein mehrkomponentiges Target, enthaltend Blei, Kupfer und gegebenenfalls weitere Elemente. Geeignete Targets sind beispielsweise homogene Legierungstargets, die in bekannter Weise durch Schmelz- bzw. pulvermetallurgische Verfahren herstellbar sind, und inhomogene Mosaiktargets, die in der Regel durch Zusammenfügen kleinerer Teilstücke unterschiedlicher chemischer Zusammensetzung oder durch Auflegen bzw. Aufkleben von kleinen scheibenförmigen Materialstücken auf homogene Targets herstellbar sind. Alternativ zu diesen Methoden kann man auch zwei oder mehr Targets unterschiedlicher Zusammensetzung gleichzeitig zerstäuben (simultanes Zerstäuben).To produce the electrode coatings, one generally atomizes a multi-component target containing lead, copper and if necessary, other elements. Suitable targets are, for example homogeneous alloy targets in a known manner can be produced by melting or powder metallurgical processes are, and inhomogeneous mosaic targets that are usually caused by Assembling smaller sections of different chemical Composition or by placing or sticking small ones disc-shaped pieces of material can be produced on homogeneous targets are. As an alternative to these methods, you can also use two or more Atomize targets of different compositions at the same time (simultaneous atomization).

Die gewünschte Schichtdicke sowie die chemische Zusammensetzung und die Mikrostruktur des Elektrodenüberzugs sind im wesentlichen durch den Prozeßgasdruck, die Zerstäubungsleistung, den Sputtermodus, die Substrattemperatur und die Beschichtungszeit zu beeinflussen.The desired layer thickness and the chemical composition and the microstructure of the electrode coating are essentially through the process gas pressure, the atomization performance, the sputtering mode, to influence the substrate temperature and the coating time.

Die Zerstäubungsleistung ist hierbei die Leistung, die zur Anregung des Plasmas aufgewendet wird, und liegt in der Regel im Bereich von 50 W bis 10 kW.The atomizing power is the power for excitation of the plasma is used, and is usually in the range from 50 W to 10 kW.

Die Substrattemperatur wählt man im allgemeinen im Bereich von Raumtemperatur bis 350, vorzugsweise von 150 bis 250°C.The substrate temperature is generally chosen in the range from Room temperature to 350, preferably from 150 to 250 ° C.

Die Beschichtungszeit hängt im wesentlichen von der angestrebten Schichtdicke ab. Typische Beschichtungsraten beim Sputtern liegen üblicherweise im Bereich von 0,1 bis 100 nm/s.The coating time essentially depends on the desired Layer thickness. Typical coating rates for sputtering are usually in the range of 0.1 to 100 nm / s.

Eine weitere bevorzugte Ausführungsform ist die Herstellung des Elektrodenüberzugs durch Aufdampfen (s. L. Holland, Vacuum Deposition of Thin Films, Chapman and Hay Ltd., 1970). Das Beschichtungsmaterial wird dabei zweckmäßig in an sich bekannter Weise in eine geeignete Aufdampfquelle wie elektrisch geheizte Verdampferschiffchen oder Elektronenstrahlverdampfer eingefüllt. Das Beschichtungsmaterial wird danach unter vermindertem Druck, üblicherweise im Bereich von 10-7 bis 10-3 mbar, verdampft, wobei sich auf der in der Vakuumanlage eingebrachten Elektrode der gewünschte Überzug bildet.Another preferred embodiment is the production of the electrode coating by vapor deposition (see L. Holland, Vacuum Deposition of Thin Films, Chapman and Hay Ltd., 1970). The coating material is expediently introduced in a manner known per se into a suitable evaporation source, such as electrically heated evaporator boats or electron beam evaporators. The coating material is then evaporated under reduced pressure, usually in the range from 10 -7 to 10 -3 mbar, the desired coating being formed on the electrode introduced in the vacuum system.

Bei der Herstellung mehrkomponentiger Schichten kann das Verdampfungsmaterial entweder in der geeigneten Zusammensetzung aus einer gemeinsamen Quelle oder simultan aus verschiedenen Quellen verdampft werden.The evaporation material can be used in the production of multi-component layers either in the appropriate composition a common source or simultaneously from different sources be evaporated.

Typische Beschichtungsraten beim Aufdampfen liegen im allgemeinen im Bereich von 10 nm/s bis 10 µm/s.Typical coating rates during evaporation are in general in the range from 10 nm / s to 10 µm / s.

In einer besonders bevorzugten Ausführungsform kann das zu beschichtende Substrat vor oder während des Aufdampfprozesses mittels eines RF-Plasmas oder mittels einer üblichen Ionenkanone mit Ionen beschossen werden, um die Mikrostruktur und die Haftung der Schichten zu verbessern. Des weiteren kann man die Mikrostruktur und die Haftung der Schichten auch durch Heizen des Substrats beeinflussen.In a particularly preferred embodiment, that to be coated can be Substrate before or during the vapor deposition process an RF plasma or using a conventional ion gun Bombarded to the microstructure and the adhesion of the ions To improve layers. You can also see the microstructure and also affect the adhesion of the layers by heating the substrate.

Die erfindungsgemäßen Elektroden kann man zur reduktiven Kupplung von olefinischen Reaktionspartnern einsetzen. Hierbei werden üblicherweise die olefinischen Reaktionspartner durch Elektrohydrodimerisierung nach an sich üblichen Methoden zur Reaktion gebracht, indem sie in einer Elektrolysezelle mit einer Anode und einer erfindungsgemäßen Elektrode als Katode der Elektrolyse ausgesetzt werden.The electrodes according to the invention can be used for reductive coupling of olefinic reactants. Here are usually the olefinic reactants by electrohydrodimerization according to conventional reaction methods brought by being in an electrolytic cell with an anode and exposed to an electrode according to the invention as a cathode of electrolysis will.

Als olefinische Reaktionspartner setzt man bevorzugt Verbindungen der Formel R1R2C=CR3X ein, in der R1, R2 und R3 gleich oder verschieden Wasserstoff oder C1-C4-Alkyl wie Methyl, Ethyl, n-Propyl, i-Propyl, n-Butyl, i-Butyl, sec.-Butyl oder tert.-Butyl, und X -CN, -CONR1R2 oder -COOR1 bedeuten. Beispielhaft seien genannt olefinische Nitrile wie Acrylnitril, Methacrylnitril, Crotonsäurenitril, 2-Methylenbutyronitril, 2-Pentennitril, 2-Methylenvaleriansäurenitril oder 2-Methylenhexansäurenitril, olefinische Carboxylate wie Acrylsäureester, Methyl- oder Ethylacrylsäureester, olefinische Carboxamide wie Acrylamid, Methacrylamid, N,N-Dimethyl- oder N,N-Diethylacrylamid, besonders bevorzugt Acrylnitril.As olefinic reactants, preference is given to using compounds of the formula R 1 R 2 C = CR 3 X in which R 1 , R 2 and R 3 are the same or different hydrogen or C 1 -C 4 alkyl, such as methyl, ethyl, n-propyl , i-Propyl, n-butyl, i-butyl, sec-butyl or tert-butyl, and X is -CN, -CONR 1 R 2 or -COOR 1 . Examples include olefinic nitriles such as acrylonitrile, methacrylonitrile, crotononitrile, 2-Methylenbutyronitril, 2-pentenenitrile, 2-Methylenvaleriansäurenitril or 2-Methylenhexansäurenitril, olefinic carboxylates such as acrylate, methyl or Ethylacrylsäureester olefinic carboxamides such as acrylamide, methacrylamide, N, N-dimethyl - or N, N-diethylacrylamide, particularly preferably acrylonitrile.

In einer besonders bevorzugten Ausführungsform stellt man mit Hilfe der erfindungsgemäßen Elektroden Adipodinitril durch Elektrohydrodimerisierung von Acrylnitril her. Die folgenden Angaben beziehen sich daher auf dieses Verfahren. In a particularly preferred embodiment, one provides With the help of the electrodes according to the invention adiponitrile Electrohydrodimerization from acrylonitrile. The following information therefore refer to this procedure.

Die Art der Elektrolysezelle ist nach bisherigen Beobachtungen unkritisch, so daß der Fachmann aus dem Spektrum der handelsüblichen Elektrolysezellen auswählen kann. Eine bevorzugte Ausführungsform der Elektrolysezelle stellt die ungeteilte Zelle dar, wobei Plattenstapelzellen oder Kapillarspaltzellen besonders bevorzugt werden. Solche Zellen sind beispielsweise in J. Electrochem. Soc. 131 (1984) 435c und J. Appl. Electrochem. 2 (1972) 59 ausführlich beschrieben.The type of electrolysis cell is based on previous observations uncritical, so that the specialist from the spectrum of commercially available Can choose electrolytic cells. A preferred embodiment the undivided cell represents the electrolytic cell represents, especially plate stack cells or capillary gap cells to be favoured. Such cells are, for example, in J. Electrochem. Soc. 131 (1984) 435c and J. Appl. Electrochemical. 2 (1972) 59 described in detail.

Als Anode kann man bekannte Anoden verwenden, bevorzugt bei ungeteilten Zellen setzt man üblicherweise Materialien mit geringer Sauerstoffüberspannung, beispielsweise Kohlenstoffstahl, Stahl, Platin, Nickel, Magnetit, Blei, Bleilegierungen oder Bleidioxid, ein (s. Hydrocarbon Processing (1981) 161).Known anodes can be used as the anode, preferably with undivided ones Cells are usually made of materials with less Oxygen overvoltage, for example carbon steel, steel, Platinum, nickel, magnetite, lead, lead alloys or lead dioxide, a (see Hydrocarbon Processing (1981) 161).

Die erfindungsgemäßen Elektroden werden als Kathoden eingesetzt, wobei man eine Zusammensetzung der folgenden Art nach den bisherigen Beobachtungen bevorzugt verwenden kann: 96,5 bis 100, vorzugsweise 98 bis 99,5 Gew.-% Blei, 0,3 bis 3, vorzugsweise 0,5 bis 2 Gew.-% Kupfer, 0 bis 3, vorzugsweise 0 bis 2 Gew.-% Silber und/oder Bismut und/oder Selen und/oder Tellur und/oder Antimon.The electrodes according to the invention are used as cathodes with a composition of the following type according to the previous ones Observations can preferably use: 96.5 to 100, preferably 98 to 99.5% by weight of lead, 0.3 to 3, preferably 0.5 up to 2% by weight copper, 0 to 3, preferably 0 to 2% by weight silver and / or bismuth and / or selenium and / or tellurium and / or antimony.

Üblicherweise enthält die Elektrolytlösung ein Leitsalz, insbesondere bei der Herstellung von Adipodinitril, da ansonsten in der Regel Propionitril zum Hauptprodukt wird und mit einer vermehrten Wasserstoffbildung zu rechnen ist. Im allgemeinen setzt man das Leitsalz in einer Menge im Bereich von 1 bis 100 mmol/kg wäßrige Elektrolytlösung, bevorzugt von 5 bis 50 mmol/kg, ein.The electrolyte solution usually contains a conductive salt, in particular in the manufacture of adiponitrile, otherwise in usually propionitrile becomes the main product and with an increased one Hydrogen formation is to be expected. Generally sets the conducting salt in an amount in the range of 1 to 100 mmol / kg aqueous electrolyte solution, preferably from 5 to 50 mmol / kg.

Als geeignete Leitsalze seien beispielhaft genannt: quartäre Ammoniumverbindungen wie Tetrabutylammoniumsalze, Ethyltributylammoniumsalze, quartäre Phosphoniumsalze, sowie Bisquartäre Ammonium- und Phosphoniumsalze wie Hexamethylenbis(dibutylethylammoniumhydroxid) (s. Hydrocarbon Processing 161 (1981); J. Electrochem. Soc. 131 (1984) 435c).Examples of suitable conductive salts are: quaternary Ammonium compounds such as tetrabutylammonium salts, ethyltributylammonium salts, quaternary phosphonium salts and bisquaternaries Ammonium and phosphonium salts such as hexamethylene bis (dibutylethylammonium hydroxide) (see Hydrocarbon Processing 161 (1981); J. Electrochem. Soc. 131 (1984) 435c).

Des weiteren enthält die Elektrolytlösung üblicherweise einen Puffer wie Hydrogenphosphat, Hydrogencarbonat, bevorzugt in Form ihrer Natriumsalze, besonders bevorzugt Dinatriumhydrogenphosphat, in einer Menge im Bereich von 10 bis 150, vorzugsweise von 30 bis 100 g/kg wäßrige Elektrolytlösung.Furthermore, the electrolyte solution usually contains one Buffers such as hydrogen phosphate, hydrogen carbonate, preferably in the form their sodium salts, particularly preferably disodium hydrogen phosphate, in an amount ranging from 10 to 150, preferably from 30 to 100 g / kg aqueous electrolyte solution.

Ferner enthält die Elektrolytlösung vorzugsweise einen Anodenkorrosionsinhibitor wie die für diese Zwecke bekannten Borate (s. Hydrocarbon Processing (1981) 161), bevorzugt Dinatriumdiborat und Orthoborsäure, in einer Menge im Bereich von 5 bis 50, bevorzugt von 10 bis 30 g/kg wäßriger Elektrolytlösung.Furthermore, the electrolyte solution preferably contains an anode corrosion inhibitor like the borates known for this purpose (see Hydrocarbon Processing (1981) 161), preferably disodium diborate and orthoboric acid, in an amount in the range of 5 to 50, preferred from 10 to 30 g / kg aqueous electrolyte solution.

Ferner enthält die Elektrolytlösung vorzugsweise einen Komplexbildner, um die Ausfällung von Eisen- und Blei-Ionen zu verhindern. Beispielhaft seien genannt Ethylendiamintetraacetat ("EDTA"), Triethanolamin ("TEOA"), Nitrilotriacetat, bevorzugt EDTA in einer Menge im Bereich von 0 bis 50, vorzugsweise 2 bis 10 g/kg wäßriger Elektrolytlösung, und/oder TEOA in einer Menge im Bereich von 0 bis 10, vorzugsweise 0,5 bis 3 g/kg wäßriger Elektrolytlösung.Furthermore, the electrolyte solution preferably contains a complexing agent, to prevent the precipitation of iron and lead ions. Examples include ethylenediaminetetraacetate ("EDTA"), triethanolamine ("TEOA"), nitrilotriacetate, preferred EDTA in an amount ranging from 0 to 50, preferably 2 to 10 g / kg aqueous electrolyte solution, and / or TEOA in an amount in the range of 0 to 10, preferably 0.5 to 3 g / kg more aqueous Electrolyte solution.

Acrylnitril setzt man im allgemeinen in einer Menge im Bereich von 10 bis 50, vorzugsweise von 20 bis 30 Gew.-%, bezogen auf die organische Phase, ein.Acrylonitrile is generally used in an amount in the range from 10 to 50, preferably from 20 to 30 wt .-%, based on the organic phase, a.

Die Reaktionstemperatur wählt man in der Regel im Bereich von 30 bis 80, vorzugsweise von 50 bis 60°C.The reaction temperature is generally chosen in the range from 30 to 80, preferably from 50 to 60 ° C.

Der pH-Wert hängt im wesentlichen von der Zusammensetzung der Elektrolytlösung ab und liegt im allgemeinen im Bereich von 6 bis 10, vorzugsweise 7,5 bis 9.The pH essentially depends on the composition of the Electrolyte solution and is generally in the range of 6 to 10, preferably 7.5 to 9.

Der Reaktionsdruck ist nach bisherigen Beobachtungen unkritisch. Man wählt ihn üblicherweise im Bereich von Normaldruck bis 10 bar.According to previous observations, the reaction pressure is not critical. It is usually chosen in the range from normal pressure to 10 bar.

Die Stromdichte wählt man im allgemeinen im Bereich von 1 bis 40, bevorzugt von 5 bis 30 A/dm2.The current density is generally chosen in the range from 1 to 40, preferably from 5 to 30 A / dm 2 .

Die Strömungsgeschwindigkeit bei kontinuierlicher Arbeitsweise liegt in der Regel im Bereich von 0,5 bis 2 m/sec, vorzugsweise 0,8 bis 1,5 m/sec.The flow rate with continuous operation is usually in the range of 0.5 to 2 m / sec, preferably 0.8 to 1.5 m / sec.

Der Vorteil der erfindungsgemäßen Elektrode liegt darin, daß beim Einsatz als Kathode bei der Elektrohydrodimerisierung von Acrylnitril zu Adipodinitril die Korrosion der Kathoden deutlich geringer ist als beim Einsatz massiver Blei- oder Bleilegierungselektroden, was zu längeren Standzeiten und einer geringeren Menge an Schwermetallen führt.The advantage of the electrode according to the invention is that Use as a cathode in the electrohydrodimerization of acrylonitrile to adiponitrile the corrosion of the cathodes is significantly less than when using solid lead or lead alloy electrodes, resulting in longer downtimes and less Amount of heavy metals.

BeispieleExamples

Die angegebenen Korrosionsgeschwindigkeiten der Elektroden wurden mittels Atomabsorptionsspektroskopie (Ermittlung der Konzentration an durch Korrosion freigesetzten Bleiionen (Kathode) und Eisenionen (Anode)) und durch Ermittlung des Gewichtsverlustes der Elektroden nach Beendigung der Reaktions bestimmt.The indicated corrosion rates of the electrodes were by means of atomic absorption spectroscopy (determination of the concentration on lead ions (cathode) released by corrosion and Iron ions (anode)) and by determining the weight loss of the electrodes after the end of the reaction.

Die angegebenen Selektivitäten wurden mit Hilfe eines Gaschromatographen ermittelt.The specified selectivities were determined using a gas chromatograph determined.

Beispiel 1 (nicht erfindungsgemäß)Example 1 (not according to the invention) Herstellung einer bleibeschichteten Elektrode durch galvanische Abscheidung aus einem FluoroboratbadManufacture of a lead coated electrode by galvanic Deposition from a fluoroborate bath

Als Kathode wurde eine runde Stahlscheibe (Durchmesser 20 mm) verwendet, die vor der galvanischen Beschichtung wie üblich entfettet und gebeizt wurde. Als Anode diente ein Bleistreifen mit den gleichen Abmessungen wie die Kathode. Die Elektroden wurden in einem Tank parallel zueinander montiert. Die Reaktionsmischung im Bad wurde durch eine mechanische Rührung bewegt, die Badtemperatur betrug 25°C.A round steel disc (diameter 20 mm) was used as the cathode used, which degreased as usual before the galvanic coating and was stained. A lead strip also served as the anode the same dimensions as the cathode. The electrodes were mounted parallel to each other in a tank. The reaction mixture in the bathroom was moved by mechanical stirring, the bath temperature was 25 ° C.

Das Beschichtungs-Bad (1 l) besaß folgende Zusammensetzung: freie Fluoroborsäure 20 g/l Borsäure 30 g/l Bleifluoroborat 90 g/l Pepton 0,5 g/l Wasser zu 1 l The coating bath (1 l) had the following composition: free fluoroboric acid 20 g / l Boric acid 30 g / l Lead fluoroborate 90 g / l Peptone 0.5 g / l water to 1 l

Es wurde mit einer Stromdichte von 10 mA/cm2 2,5 h galvanisiert. Die Schichtdicke betrug 50 µm.It was galvanized with a current density of 10 mA / cm 2 for 2.5 h. The layer thickness was 50 µm.

Beispiel 2Example 2 Herstellung einer erfindungsgemäßen Bleielektrode durch galvanische Abscheidung, enthaltend 1,8 Gew.-% KupferProduction of a lead electrode according to the invention by galvanic Deposition containing 1.8% by weight copper

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 2,6 g/l Kupferfluoroborat enthielt. Die Schichtdicke betrug 50 µm.The procedure was as in Example 1, with the difference that the coating bath additionally contained 2.6 g / l copper fluoroborate. The layer thickness was 50 µm.

Beispiel 3Example 3 Herstellung einer erfindungsgemäßen Bleielektrode durch galvanische Abscheidung, enthaltend 0,8 Gew.-% KupferProduction of a lead electrode according to the invention by galvanic Deposition containing 0.8% by weight copper

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 0,7 g/l Kupferfluoroborat enthielt. Die Schichtdicke betrug 50 µm.The procedure was as in Example 1, with the difference that the coating bath additionally contained 0.7 g / l copper fluoroborate. The layer thickness was 50 µm.

Beispiel 4Example 4 Herstellung einer erfindungsgemäßen Bleielektrode durch galvanische Abscheidung, enthaltend 1,3 Gew.-% KupferProduction of a lead electrode according to the invention by galvanic Deposition containing 1.3% by weight copper

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 1,6 g/l Kupferfluoroborat enthielt. Die Schichtdicke betrug 50 µm.The procedure was as in Example 1, with the difference that the coating bath additionally contained 1.6 g / l copper fluoroborate. The layer thickness was 50 µm.

Beispiel 5Example 5 Herstellung einer erfindungsgemäßen Bleielektrode durch galvanische Abscheidung, enthaltend 3,7 Gew.-% KupferProduction of a lead electrode according to the invention by galvanic Deposition containing 3.7% by weight copper

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 5,6 g/l Kupferfluoroborat enthielt. Die Schichtdicke betrug 50 µm.The procedure was as in Example 1, with the difference that the coating bath additionally contained 5.6 g / l copper fluoroborate. The layer thickness was 50 µm.

Beispiel 6Example 6 Herstellung einer erfindungsgemäßen Bleielektrode durch galvanische Abscheidung, enthaltend 2,2 Gew.-% Kupfer und 1,3 Gew.-% BismutProduction of a lead electrode according to the invention by galvanic Deposition containing 2.2% by weight copper and 1.3% by weight Bismuth

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 1,25 g/l Kupferfluoroborat und 0,5 g/l Bismutnitrat enthielt. Die Schichtdicke betrug 50 µm.The procedure was as in Example 1, with the difference that the coating bath additionally 1.25 g / l copper fluoroborate and Contained 0.5 g / l bismuth nitrate. The layer thickness was 50 µm.

Beispiel 7Example 7 Herstellung einer erfindungsgemaßen Bleielektrode durch galvanische Abscheidung, enthaltend 1,3 Gew.-% Kupfer und 0,5 Gew.-% TellurProduction of a lead electrode according to the invention by galvanic Deposition containing 1.3% by weight copper and 0.5% by weight Tellurium

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 1,5 g/l Kupferfluoroborat und 0,65 g/l Tellurdioxid enthielt. Die Schichtdicke betrug 50 µm. The procedure was as in Example 1, with the difference that the coating bath additionally 1.5 g / l copper fluoroborate and Contained 0.65 g / l tellurium dioxide. The layer thickness was 50 µm.

Beispiel 8Example 8 Herstellung einer erfindungsgemäßen Bleielektrode durch galvanische Abscheidung, enthaltend 1,3 Gew.-% Kupfer und 0,1 Gew.-% SelenProduction of a lead electrode according to the invention by galvanic Deposition containing 1.3% by weight copper and 0.1% by weight selenium

Es wurde wie in Beispiel 1 verfahren, mit dem Unterschied, daß das Beschichtungsbad zusätzlich 2,7 g/l Kupferfluoroborat und 0,15 g/l Selendioxid enthielt. Die Schichtdicke betrug 50 µm.The procedure was as in Example 1, with the difference that the coating bath additionally 2.7 g / l copper fluoroborate and Contained 0.15 g / l selenium dioxide. The layer thickness was 50 µm.

Beispiel 9Example 9 Herstellung einer erfindungsgemäßen Elektrode durch galvanische Abscheidung analog Beispiel 1Production of an electrode according to the invention by galvanic Deposition analogous to example 1

Als Kathode wurden Stahlbleche (3 cm x 80 cm) verwendet. Die Anode bestand aus einem Bleistreifen mit den gleichen Maßen.Steel sheets (3 cm x 80 cm) were used as the cathode. The Anode consisted of a pencil strip of the same dimensions.

Das Beschichtungsbad (10 1) wies folgende Zusammensetzung auf: freie Methansulfonsäure 32 g/l Bleimethansulfonat 70 g/l Kupfermethansulfonat 5,2 g/l Lutensol® AP 10 10 g/l The coating bath (10 1) had the following composition: free methanesulfonic acid 32 g / l Lead methanesulfonate 70 g / l Copper methanesulfonate 5.2 g / l Lutensol® AP 10 10 g / l

Es wurde mit einer Stromdichte von 12,5 mA/cm2 2 h galvanisiert. Die Schichtdicke betrug 60 µm. Der Überzug enthielt 1 Gew.-% Kupfer. It was galvanized with a current density of 12.5 mA / cm 2 for 2 h. The layer thickness was 60 µm. The coating contained 1% by weight copper.

Beispiel 10Example 10

Eine runde Stahlelektrode mit einem Durchmesser von 20 mm wurde in eine Kathodenzerstäubungsanlage eingebracht. Parallel zu dem Stahlsubstrat wurde in einem Abstand von 60 mm ein rundes Mosaik-Target (Durchmesser 150 mm), bestehend aus Blei mit aufgelegten Kupfer-Scheiben (Durchmesser 2 mm), eingesetzt. Der Flächenbelegungsgrad ist in Tabelle 1 wiedergegeben. Die Anlage wurde mit einem zweistufigen Pumpsystem auf einen Druck von 10-6 mbar evakuiert.A round steel electrode with a diameter of 20 mm was placed in a cathode sputtering system. Parallel to the steel substrate, a round mosaic target (diameter 150 mm) consisting of lead with copper discs (diameter 2 mm) was used at a distance of 60 mm. The area occupancy rate is shown in Table 1. The system was evacuated to a pressure of 10 -6 mbar using a two-stage pump system.

Das Substrat wurde auf eine Temperatur von 200°C erwärmt. Danach wurde Argon bis zu einem Druck von 9 x 10-3 mbar eingelassen. Durch Anlegen einer RF-Spannung mit einer Leistung von 500 W an den Substrathalter wurde das Substrat für die Dauer von 1 min einer Sputterätzbehandlung unterzogen. Nach Abschluß der Sputterätzbehandlung wurde der Ar-Druck auf 5 x 10-3 mbar eingestellt. Durch Anlegen einer DC-Spannung an das Target (Leistung 1000 W) und einer RF-Spannung an den Substrathalter (Leistung 200 W) wurde ein Zerstäubungsplasma gezündet und auf dem Edelstahlsubstrat eine (Pb-Cu)-Schicht mit einer Dicke von 10 µm abgeschieden. Der Cu-Gehalt der so hergestellten Elektroden ist in Tabelle 1 wiedergegeben. Flächenbelegung der Cu-Chips [%] Cu-Gehalt des Elektrodenüberzugs [Gew.-%] a 0 0 b 0,43 0,3 c 0,86 0,8 d 1,7 1,2 e 3,4 2,4 f 4,2 3,0 g 18 13,0 The substrate was heated to a temperature of 200 ° C. Then argon was admitted to a pressure of 9 x 10 -3 mbar. The substrate was subjected to a sputter etching treatment for 1 min by applying an RF voltage with a power of 500 W to the substrate holder. After completion of the sputter etching treatment, the Ar pressure was set to 5 x 10 -3 mbar. An atomizing plasma was ignited by applying a DC voltage to the target (power 1000 W) and an RF voltage to the substrate holder (power 200 W) and a (Pb-Cu) layer with a thickness of 10 μm was deposited on the stainless steel substrate . The Cu content of the electrodes produced in this way is shown in Table 1. Area coverage of the Cu chips [%] Cu content of the electrode coating [% by weight] a 0 0 b 0.43 0.3 c 0.86 0.8 d 1.7 1.2 e 3.4 2.4 f 4.2 3.0 G 18th 13.0

Beispiel 11Example 11 Herstellung von Adipodinitril mit einer Kathode aus massivem Blei (Vergleich)Manufacture of adiponitrile with a solid lead cathode (Comparison)

Apparaturapparatus Ungeteilte ElektrolysezelleUndivided electrolytic cell Anodeanode Stahlstole Kathodecathode massives Blei solid lead ElektrodenflächeElectrode surface jeweils 3,14 cm2 3.14 cm 2 each ElektrodenabstandElectrode gap 2 mm2 mm DurchflußgeschwindigkeitFlow rate 1,1 m/sec1.1 m / sec StromdichteCurrent density 20 A/dm2 20 A / dm 2 Temperaturtemperature 55°C55 ° C

Durch die Elektrolysezelle wurde die Elektrolytlösung gepumpt. Von dort gelangte sie in ein Trenngefäß, wo sich das gebildete Adipodinitril als organische Phase abschied. Anschließend wurde der wäßrige Elektrolyt zurück in die Elektrolysezelle gepumpt.The electrolytic solution was pumped through the electrolytic cell. From there it came into a separation vessel, where the formed Adiponitrile as an organic phase. Then was the aqueous electrolyte is pumped back into the electrolytic cell.

Die wäßrige Phase bestand aus:

  • 7 Gew.-% Dinatriumhydrogenphosphat,
  • 2 Gew.-% Natriumdiborat,
  • 2 Gew.-% Acrylnitril,
  • 0,4 Gew.-% Ethylendiamintetraessigsäure,
  • 0,1 Gew.-% Triethanolamin,
  • 10,5 mmol/kg Hexamethylenbis(dibutylethylammonium)phosphat (Leitsalz).
    Der pH-Wert wurde mit Phosphorsäure auf 8,5 eingestellt.
    • The aqueous phase consisted of:
  • 7% by weight disodium hydrogen phosphate,
  • 2% by weight sodium diborate,
  • 2% by weight acrylonitrile,
  • 0.4% by weight of ethylenediaminetetraacetic acid,
  • 0.1% by weight of triethanolamine,
  • 10.5 mmol / kg hexamethylene bis (dibutylethylammonium) phosphate (conductive salt).
    The pH was adjusted to 8.5 with phosphoric acid.

    • Die organische Phase bestand aus:The organic phase consisted of:

    30 Vol-% Acrylnitril und 70 Vol-% Korksäuredinitril. Das Korksäuredinitril ermöglichte eine genaue Bestimmung des gebildeten Adipodinitrils.30% by volume acrylonitrile and 70% by volume cork acid dinitrile. The cork acid dinitrile allowed an exact determination of the formed adiponitrile.

    Vor Beginn der Reaktion wurden die beiden Phasen durch Umpumpen äquilibriert, so daß Acrylnitril in der waßrigen Phase gelöst wurde (ca. 2 Gew.-%). Die restlichen Komponenten verteilten sich entsprechend ihrer Verteilungsgleichgewichte zwischen den beiden Phasen. Insbesondere lösten sich teilweise das Leitsalz sowie ca. 4 Gew.-% Wasser in der organischen Phase, so daß die Acrylnitrilkonzentration in der organischen Phase ca. 26 Vol-% betrug.Before the start of the reaction, the two phases were pumped around equilibrated so that acrylonitrile is dissolved in the aqueous phase was (about 2 wt .-%). The remaining components were distributed according to their distributional equilibrium between the two Phases. In particular, the conductive salt and approx. 4 wt .-% water in the organic phase, so that the acrylonitrile concentration was about 26% by volume in the organic phase.

    Während der Elektrolyse wurde Acrylnitril so zudosiert, daß dessen Konzentration in der organischen Phase zwischen 23 und 26 Vol-% betrug. In der wäßrigen Phase wurden EDTA, TEOA und Leitsalz nachdosiert.During the electrolysis, acrylonitrile was metered in so that Concentration in the organic phase between 23 and Was 26% by volume. In the aqueous phase, EDTA, TEOA and Leitsalz added.

    Die Elektrolyse wurde 90 Stunden kontinuierlich betrieben. Nach 90 h ergab sich eine Korrosionsgeschwindigkeit der massiven Bleikathode von 0,35 mm/Jahr (0,2 mg/Ah). Die Selektivität für Adipodinitril betrug 90,3 %. The electrolysis was operated continuously for 90 hours. After The massive lead cathode showed a corrosion rate of 90 hours of 0.35 mm / year (0.2 mg / Ah). The selectivity for adiponitrile was 90.3%.

    Beispiel 12 (Vergleichsversuch zu Beispielen 13 - 19)Example 12 (comparative experiment to Examples 13-19) Durchführung analog zu Beispiel 11, jedoch Verwendung einer galvanisch abgeschiedenen Bleischicht (0,05 mm) auf Stahl (Herstellung gemäß Beispiel 1)Carried out analogously to Example 11, but using a galvanic one deposited lead layer (0.05 mm) on steel (manufacture according to example 1)

    Die Elektrolyse wurde 90 Stunden kontinuierlich betrieben. nach 90 h ergab sich eine Korrosionsgeschwindigkeit der Bleibeschichtung von 0,25 mm/Jahr (0,14 mg/Ah), die Selektivität für Adipodinitril betrug 90,4 %. The electrolysis was operated continuously for 90 hours. after The corrosion rate of the lead coating was 90 h of 0.25 mm / year (0.14 mg / Ah), the selectivity for adiponitrile was 90.4%.

    Beispiel 13Example 13 Wie Beispiel 11, jedoch Verwendung einer Legierungs-Kathode mit 1,8 Gew.-% Kupfer (Herstellung gemäß Beispiel 2)As example 11, but using an alloy cathode with 1.8% by weight copper (production according to Example 2)

    Die Elektrolyse wurde 200 Stunden kontinuierlich betrieben. Nach 200 h ergab sich eine Korrosionsgeschwindigkeit von 0,05 mm/Jahr (0,03 mg/Ah), die Selektivität betrug 90,9 %. The electrolysis was operated continuously for 200 hours. After A corrosion rate of 0.05 mm / year resulted for 200 h (0.03 mg / Ah), the selectivity was 90.9%.

    Beispiel 14Example 14 Wie Beispiel 11, jedoch Verwendung einer Legierungs-Kathode mit 0,8 Gew.-% Kupfer (Herstellung gemäß Beispiel 3)As example 11, but using an alloy cathode with 0.8% by weight copper (production according to Example 3)

    Die Elektrolyse wurde 209 Stunden kontinuierlich betrieben. Nach 209 h ergab sich eine Korrosionsgeschwindigkeit der Blei/KupferKathode von 0,16 mm/Jahr (0,09 mg/Ah), die Selektivität betrug 91,4 %.The electrolysis was operated continuously for 209 hours. After The corrosion rate of the lead / copper cathode was 209 h of 0.16 mm / year (0.09 mg / Ah), the selectivity was 91.4%.

    Beispiel 15Example 15 Wie Beispiel 11, jedoch Verwendung einer Legierungs-Kathode mit 1,3 Gew.-% Kupfer (Herstellung gemäß Beispiel 4)As example 11, but using an alloy cathode with 1.3% by weight copper (preparation according to Example 4)

    Die Elektrolyse wurde 96 Stunden kontinuierlich betrieben. Nach 96 h ergab sich eine Korrosionsgeschwindigkeit der Blei/Kupfer-Kathode von 0,07 mm/Jahr (0,04 mg/Ah), die Selektivität betrug 90,4 %.The electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.07 mm / year (0.04 mg / Ah), the selectivity was 90.4%.

    Beispiel 16 (Vergleichsbeispiel)Example 16 (comparative example) Wie Beispiel 11, jedoch Verwendung einer Legierungs-Kathode mit 3,7 Gew.-% Kupfer (Herstellung gemäß Beispiel 5)As example 11, but using an alloy cathode with 3.7% by weight copper (production according to Example 5)

    Die Elektrolyse wurde 90 Stunden kontinuierlich betrieben. Nach 90 h ergab sich eine Korrosionsgeschwindigkeit der Blei/Kupfer-Kathode von 0,05 mm/Jahr (0,03 mg/Ah), die Selektivität betrug 88,8 %.The electrolysis was operated continuously for 90 hours. After The corrosion rate of the lead / copper cathode was 90 h of 0.05 mm / year (0.03 mg / Ah), the selectivity was 88.8%.

    Beispiel 17Example 17 Wie Beispiel 11, jedoch Verwendung einer ternären Legierungs-Kathode mit 2,2 Gew.-% Kupfer und 1,3 Gew.-% Bi (Herstellung gemäß Beispiel 6)As example 11, but using a ternary alloy cathode with 2.2% by weight copper and 1.3% by weight Bi (manufactured according to Example 6

    Die Elektrolyse wurde 96 Stunden kontinuierlich betrieben. Nach 96 h ergab sich eine Korrosionsgeschwindigkeit der Blei/Kupfer-Kathode von 0,08 mm/Jahr (0,045 mg/Ah), die Selektivität betrug 90,0 %.The electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.08 mm / year (0.045 mg / Ah), the selectivity was 90.0%.

    Beispiel 18Example 18 Wie Beispiel 11, jedoch Verwendung einer ternären Legierungs-Kathode mit 1,3 Gew.-% Kupfer und 0,5 Gew.-% Te (Herstellung gemäß Beispiel 7)As example 11, but using a ternary alloy cathode with 1.3% by weight copper and 0.5% by weight Te (production according to Example 7)

    Die Elektrolyse wurde 96 Stunden kontinuierlich betrieben. Nach 96 h ergab sich eine Korrosionsgeschwindigkeit der Blei/Kupfer-Kathode von 0,09 mm/Jahr (0,05 mg/Ah), die Selektivität betrug 90,9 %.The electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.09 mm / year (0.05 mg / Ah), the selectivity was 90.9%.

    Beispiel 19Example 19 Wie Beispiel 11, jedoch Verwendung einer ternären Legierungs-Kathode mit 1,3 Gew.-% Kupfer und 0,1 Gew.-% Se (Herstellung gemäß Beispiel 8)As example 11, but using a ternary alloy cathode with 1.3% by weight copper and 0.1% by weight Se (production according to Example 8)

    Die Elektrolyse wurde 96 Stunden kontinuierlich betrieben. Nach 96 h ergab sich eine Korrosionsgeschwindigkeit der Blei/Kupfer-Kathode von 0,05 mm/Jahr (0,03 mg/Ah), die Selektivität betrug 90,9 %.The electrolysis was operated continuously for 96 hours. After The corrosion rate of the lead / copper cathode was 96 h of 0.05 mm / year (0.03 mg / Ah), the selectivity was 90.9%.

    Beispiel 20Example 20

    Apparaturapparatus Ungeteilte ElektrolysezelleUndivided electrolytic cell Anodeanode Stahlstole Kathodecathode galvanisch abgeschiedene Blei-Kupfer-Legierungsschicht auf Stahl mit 0,8 Gew.-% Kupfer (0,05 mm) (Herstellung gemäß Beispiel 28)electroplated lead-copper alloy layer on steel with 0.8% by weight copper (0.05 mm) (production according to example 28) ElektrodenflächeElectrode surface jeweils 80 cm · 2 cmeach 80 cm x 2 cm ElektrodenabstandElectrode gap 1,3 mm1.3 mm DurchflußgeschwindigkeitFlow rate 1,1 m/sec1.1 m / sec StromdichteCurrent density 21,8 A/dm2 21.8 A / dm 2 Temperaturtemperature 55°C55 ° C

    Durch die Elektrolysezelle wurde die wäßrige Phase gepumpt. Das gebildete Adipodinitril schied sich in einem Trenngefäß als organische Phase ab. Anschließend wurde der wäßrige Elektrolyt wieder in die Elektrolysezelle zurückgeführt.The aqueous phase was pumped through the electrolytic cell. The The adiponitrile formed separated as organic in a separating vessel Phase. Then the aqueous electrolyte was restored returned to the electrolytic cell.

    Die wäßrige Phase bestand aus:

  • 88,5 Gew.-% Wasser,
  • 7 Gew.-% Dinatriumhydrogenphosphat,
  • 2 Gew.-% Natriumdiborat,
  • 2 Gew.-% Acrylnitril,
  • 0,4 Gew.-% Ethylendiamintetraessigsäure,
  • 0,1 Gew.-% Triethanolamin, sowie
  • 10,5 mmol/kg Hexamethylenbis(dibutylethylammonium)phosphat und hatte einen pH-Wert von 8,5.
    • The aqueous phase consisted of:
  • 88.5% by weight of water,
  • 7% by weight disodium hydrogen phosphate,
  • 2% by weight sodium diborate,
  • 2% by weight acrylonitrile,
  • 0.4% by weight of ethylenediaminetetraacetic acid,
  • 0.1% by weight of triethanolamine, and
  • 10.5 mmol / kg hexamethylene bis (dibutylethylammonium) phosphate and had a pH of 8.5.

    • Die organische Phase bestand aus:
    30 Vol-% Acrylnitril und 70 Vol-% Adipodinitril.    The organic phase consisted of:
    30 vol% acrylonitrile and 70 vol% adiponitrile.

    Vor Beginn der Reaktion wurden die beiden Phasen durch Umpumpen äquilibriert, so daß Acrylnitril in der wäßrigen Phase gelöst wurde (ca. 2 Gew.-%). Die restlichen Komponenten verteilten sich entsprechend ihrer Verteilungsgleichgewichte zwischen den beiden Phasen. Insbesondere lösten sich teilweise das Leitsalz sowie ca. 4 Gew.-% Wasser in der organischen Phase, so daß die Acrylnitrilkonzentration in der organischen Phase ca. 24 Vol-% betrug.Before the start of the reaction, the two phases were pumped around equilibrated so that acrylonitrile is dissolved in the aqueous phase was (about 2 wt .-%). The remaining components were distributed according to their distributional equilibrium between the two Phases. In particular, the conductive salt and approx. 4 wt .-% water in the organic phase, so that the acrylonitrile concentration was about 24% by volume in the organic phase.

    Während der Elektrolyse wurde kontinuierlich Acrylnitril so zudosiert, daß dessen Konzentration in der organischen Phase konstant blieb. Ebenso wurde kontinuierlich wäßrige Phase ersetzt. Gleichzeitig wurden aus beiden Phasen Teilströme entnommen.Acrylonitrile became so continuously during the electrolysis added that its concentration in the organic phase constant stayed. The aqueous phase was also continuously replaced. At the same time, partial flows were taken from both phases.

    Nach 650 h ergab sich eine Korrosionsgeschwindigkeit der Legierungselektrode von 0,05 mm/Jahr (0,03 mg/Ah), die Selektivität für Adipodinitril betrug 91,4 %.After 650 h, the alloy electrode showed a corrosion rate of 0.05 mm / year (0.03 mg / Ah), the selectivity for adiponitrile was 91.4%.

    Beispiel 21Example 21 Herstellung einer Legierungskathode durch galvanische Abscheidung in einer durch eine Anionenaustauschermembran geteilten BeschichtungszelleProduction of an alloy cathode by electrodeposition in a coating cell divided by an anion exchange membrane

    Es wurde verfahren wie in Beispiel 9, jedoch wurde der Katholyt und der Anolyt durch eine Anionenaustauschermembran (Aciplex® ACH-45T) getrennt. Dadurch konnte während der Beschichtung eine Abscheidung von Kupfer auf der Anode unterdrückt werden.The procedure was as in Example 9, but the catholyte and the anolyte through an anion exchange membrane (Aciplex® ACH-45T) separately. This allowed a Deposition of copper on the anode can be suppressed.

    Das Bad besaß folgende Zusammensetzung: Katholyt freie Methansulfonsäure 48 g/l Bleimethansulfonat 64 g/l Kupfermethansulfonat 5 g/l Lutensol® AP 10 10 g/l Anolyt freie Methansulfonsäure 42 g/l Bleimethansulfonat 95 g/l The bathroom had the following composition: Catholyte free methanesulfonic acid 48 g / l Lead methanesulfonate 64 g / l Copper methanesulfonate 5 g / l Lutensol® AP 10 10 g / l Anolyte free methanesulfonic acid 42 g / l Lead methanesulfonate 95 g / l

    Es wurde 2 h mit einer Stromdichte von 12,5 mA/cm2 galvanisiert. Die Schichtdicke betrug 60 µm. Die Legierung enthielt 0,8 Gew.-% Kupfer.Electroplating was carried out for 2 hours at a current density of 12.5 mA / cm 2 . The layer thickness was 60 µm. The alloy contained 0.8% by weight of copper.

    Beispiel 22 (Vergleichsversuch zu Beispiel 23)Example 22 (Comparative Experiment to Example 23) Wie Beispiel 11, jedoch Verwendung einer durch Sputtern aufgebrachten Bleischicht-Kathode (Herstellung gemäß Beispiel 10a)As example 11, but using a sputtered one Lead layer cathode (production according to example 10a)

    Die Elektrolyse wurde 132 Stunden kontinuierlich betrieben. Nach 132 h ergab sich eine Korrosionsgeschwindigkeit der Bleibeschichtung von 0,14 mm/Jahr (0,08 mg/Ah), die Selektivität für Adipodinitril betrug 90,6 %.The electrolysis was operated continuously for 132 hours. After The lead coating showed a corrosion rate of 132 h of 0.14 mm / year (0.08 mg / Ah), the selectivity for adiponitrile was 90.6%.

    Beispiel 23Example 23 Wie Beispiel 11, jedoch Verwendung einer gesputterten Blei-Kupfer-Kathode mit 2,4 Gew.-% Kupfer (Herstellung gemäß Beispiel 10e)As example 11, but using a sputtered lead-copper cathode with 2.4% by weight copper (preparation according to example 10e)

    Die Elektrolyse wurde 90 Stunden kontinuierlich betrieben. Nach 90 h ergab sich eine Korrosionsgeschwindigkeit der Blei/Kupfer-Kathode von 0,08 mm/Jahr (0,045 mg/Ah), die Selektivität für Adipodinitril betrug 90,3 %.The electrolysis was operated continuously for 90 hours. After The corrosion rate of the lead / copper cathode was 90 h of 0.08 mm / year (0.045 mg / Ah), the selectivity for adiponitrile was 90.3%.

    Claims (7)

    1. An electrode consisting of an electrically conductive core essentially comprising iron and an electrically conductive single-layer coating comprising lead and from 0.3 to 3.5% by weight of copper and, if required, further elements selected from the group consisting of silver, selenium, tellurium, bismuth and antimony.
    2. An electrode as claimed in claim 1, wherein the electrically conductive coating is applied to the electrically conductive core by electroplating or a physical deposition method selected from the group consisting of vapor deposition, sputtering and arc coating.
    3. An electrochemical cell having at least one electrode as claimed in claim 1 or 2 which is connected as the cathode.
    4. A process for the production of an electrode as claimed in any of claims 1 to 3, wherein the electrically conductive coating is applied to the electrically conductive core by electroplating or by a physical deposition method selected from the group consisting of vapor deposition, sputtering and arc coating.
    5. A process for the reductive coupling of olefinic reactants by electrohydrodimerization in a conventional manner, wherein the reactants are exposed to electrolysis in an electrochemical cell as claimed in claim 3.
    6. A process as claimed in claim 5, wherein the olefinic reactants used are compounds of the general formula R1R2C=CR3X, where R1, R2 and R3 are identical or different and are each hydrogen or C1-C4-alkyl and X is CN, CONR1R2 or COOR1.
    7. A process as claimed in claim 6, wherein the olefinic reactant used is acrylonitrile.
    EP94108425A 1993-06-16 1994-06-01 Electrode comprising an iron containing substrate and a lead containing coating Expired - Lifetime EP0635587B1 (en)

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    US9017528B2 (en) * 2011-04-14 2015-04-28 Tel Nexx, Inc. Electro chemical deposition and replenishment apparatus
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    US3193483A (en) * 1964-01-14 1965-07-06 Monsanto Co Electrolysis of acrylamides
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