EP0224790A1 - Verfahren zur Reinigung von Kathoden bei der Alkalichloridelektrolyse - Google Patents

Verfahren zur Reinigung von Kathoden bei der Alkalichloridelektrolyse Download PDF

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Publication number
EP0224790A1
EP0224790A1 EP19860115954 EP86115954A EP0224790A1 EP 0224790 A1 EP0224790 A1 EP 0224790A1 EP 19860115954 EP19860115954 EP 19860115954 EP 86115954 A EP86115954 A EP 86115954A EP 0224790 A1 EP0224790 A1 EP 0224790A1
Authority
EP
European Patent Office
Prior art keywords
cell
electrolysis
catholyte
cathodes
alkalichlorides
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19860115954
Other languages
German (de)
English (en)
French (fr)
Inventor
Franz-Rudolf Dr. Minz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayer AG
Original Assignee
Bayer AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bayer AG filed Critical Bayer AG
Publication of EP0224790A1 publication Critical patent/EP0224790A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • C25B15/00—Operating or servicing cells

Definitions

  • the present invention relates to a method for removing cathodically deposited metallic contaminants in alkali metal chloride electrolysis.
  • any conductive material that is stable under the electrolysis conditions can be used as the cathode material in alkali metal chloride electrolysis. Since the cell voltage is determined, among other things, by the deposition potential of the protons on the cathode, efforts are made to select a material with the lowest possible H2 overvoltage. Such materials are described in EP-A 129231, EP-A 129374 and DE-A 3322169.
  • the low rate of corrosion of a material considered to be stable is sufficient to poison the catholyte with traces.
  • the gettering effect of the cathode shifts the initially low H2 deposition potential to higher values, i.e. the cell voltage increases over time. This increase in voltage is directed among other things on the type and concentration of impurities; so z.
  • B. a content of 1 ppm Fe in the supplied electrolyte can increase the cell voltage in the course of a few weeks to the level of a pure mild steel cathode.
  • the object of the present invention is to eliminate these disadvantages which arise for optimal operation of an alkali metal chloride electrolysis.
  • the present invention thus relates to a process for removing cathodically deposited metallic impurities in alkali metal chloride electrolysis, characterized in that the electrolytic cell is short-circuited and the electrolyte is discharged.
  • the method according to the invention can be used regardless of the type of electrolysis, i.e. for the case that the electrolysis cell is an undivided cell, in particular an amalgam cell, or also for the case that the electrolysis cell is a divided cell, in particular a diaphragm or membrane cell.
  • the short circuit should be carried out for 10 minutes to 10 hours. Particularly favorable results, also with regard to economic factors, are obtained if the short circuit is carried out for 30 minutes to 5 hours.
  • An advantage of the method according to the invention is that existing installations can be used.
  • a switch for bridging a cell is available according to the state of the art in order to be able to remove the corresponding cell from the circuit when repairing a cell or when replacing the diaphragm or the membranes.
  • the method according to the invention avoids the use of non-electrolyte additives, such as those e.g. in EP-A 132 816 and EP-A 136 794.
  • the contaminants deposited on the cathode dissolve again when the cell is electrically bridged.
  • the advantages of the method according to the invention are also achieved in the case of the membrane or diphragm method. if only the catholyte is removed.
  • the cathode chamber should also be flushed with catholyte.
  • the running catholyte is not returned to the circuit, but is collected separately.
  • the liquor obtained here can be used advantageously for alkalizing the brine before cleaning.
  • the cell was rinsed with 1/3 of the amount of electrolyte usual during operation.
  • the running catholyte had a 10-fold higher iron concentration than the feed.
  • the catholyte thus enriched with detached Fe was collected separately and used for alkaline "brine precipitation".
  • the cell voltage was 200 mV below the switch-off value and rose again to the same extent as before.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
EP19860115954 1985-11-29 1986-11-18 Verfahren zur Reinigung von Kathoden bei der Alkalichloridelektrolyse Withdrawn EP0224790A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19853542234 DE3542234A1 (de) 1985-11-29 1985-11-29 Verfahren zur reinigung von kathoden bei der alkalichloridelektrolyse
DE3542234 1985-11-29

Publications (1)

Publication Number Publication Date
EP0224790A1 true EP0224790A1 (de) 1987-06-10

Family

ID=6287181

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860115954 Withdrawn EP0224790A1 (de) 1985-11-29 1986-11-18 Verfahren zur Reinigung von Kathoden bei der Alkalichloridelektrolyse

Country Status (5)

Country Link
EP (1) EP0224790A1 (fi)
JP (1) JPS62133096A (fi)
DE (1) DE3542234A1 (fi)
FI (1) FI864842A (fi)
NO (1) NO864508D0 (fi)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2020480A1 (de) * 1970-04-27 1971-11-11 Basf Ag Verfahren zur Elektrolyse von Alkalichloriden
US4174269A (en) * 1978-06-21 1979-11-13 Ppg Industries, Inc. Method of treating electrodes
EP0132816A1 (en) * 1983-07-26 1985-02-13 Kanegafuchi Kagaku Kogyo Kabushiki Kaisha A method for preventing degradation in activity of a low hydrogen overvoltage cathode
EP0136794A2 (en) * 1983-08-22 1985-04-10 Imperial Chemical Industries Plc Treatment of cathodes for use in electrolytic cell

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2020480A1 (de) * 1970-04-27 1971-11-11 Basf Ag Verfahren zur Elektrolyse von Alkalichloriden
US4174269A (en) * 1978-06-21 1979-11-13 Ppg Industries, Inc. Method of treating electrodes
EP0132816A1 (en) * 1983-07-26 1985-02-13 Kanegafuchi Kagaku Kogyo Kabushiki Kaisha A method for preventing degradation in activity of a low hydrogen overvoltage cathode
EP0136794A2 (en) * 1983-08-22 1985-04-10 Imperial Chemical Industries Plc Treatment of cathodes for use in electrolytic cell

Also Published As

Publication number Publication date
DE3542234A1 (de) 1987-06-04
FI864842A0 (fi) 1986-11-27
NO864508D0 (no) 1986-11-12
FI864842A (fi) 1987-05-30
JPS62133096A (ja) 1987-06-16

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Inventor name: MINZ, FRANZ-RUDOLF, DR.