US3336209A - Reducing the excess voltage in electrolysis of aqueous hydrochloric acid in diaphragm cells - Google Patents

Reducing the excess voltage in electrolysis of aqueous hydrochloric acid in diaphragm cells Download PDF

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Publication number
US3336209A
US3336209A US401922A US40192264A US3336209A US 3336209 A US3336209 A US 3336209A US 401922 A US401922 A US 401922A US 40192264 A US40192264 A US 40192264A US 3336209 A US3336209 A US 3336209A
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United States
Prior art keywords
palladium
hydrochloric acid
electrolysis
aqueous hydrochloric
reducing
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Expired - Lifetime
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US401922A
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English (en)
Inventor
Hirschberg Rudolf
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Hoechst AG
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Hoechst AG
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Publication date
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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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/24—Halogens or compounds thereof
    • C25B1/26—Chlorine; Compounds thereof

Definitions

  • the present invention relates to the electrolysis of aqueous hydrochloric acid in diaphragm cells.
  • portions of the platinum layer which have dropped off the electrode may be withdrawn from time to time from the bottom of the electrolytic cell, dissolved in suitable manner and added again to the electrolyte.
  • a mode of operation presents considerable difiiculties owing to the usual filter press-like construction of the electrolytic cells containing narrow individual cells and therefore requires repeated and undesired interruptions of the electrolysis.
  • a relatively small saving in voltage is obtained by these known measures, since the hydrogen overvoltage can be signficantly reduced only for a short period of time because of the continuous degeneration of the layer.
  • the process according to the invention can be carried out by adding a soluble palladium salt, for example palladium chloride, to the electrolyte in an electrolytic cell.
  • a soluble palladium salt for example palladium chloride
  • the palladium salt is added in the form of a solution, and more advantageously in the form of a hydrochloric acid solution and in an amount of 0.2 to 2 grams, preferably 0.8 to 1.5 grams of palladium for 1 square meter of active electrode surface.
  • the voltage in the individual cells drops practically by the amount of the hydrogen overvoltage, for example from about 2.35 volts to 2.00 volts with a load of 8000 amperes.
  • the voltage in the individual cells increases again to 2.15 volts. A further increase in voltage cannot be observed even after a prolonged operating time.
  • the palladium salt is added not all at once but continuously or periodically in small amounts. It has surprisingly been found that additions of about 0.5 to 1.0 milligrams of palladium per hour and square meter of cathode surface are sufficient to suppress practically completely the hydrogen overvoltage for any period of time. Consequently, a continuous electrolysis according to the process of the invention takes place without hydrogen overvoltage and a regeneration of the active layer is not necessary.
  • the cost of the metal used corresponds with only a small fraction of the electric energy saved and, therefore, a recovery of the palladium used can be dispensed with.
  • the amount of palladium deposited on the cathode surface after one year of operation is 5 to 10 grams of palladium per square meter so that the metal can be supplied over a very long period of time without the formation on the electrodes of thick deposits which would detrimentally affect the electrolysis.
  • the palladium layer on the electrodes can be regenerated by a short disconnection of the cell.
  • the palladium layer is then readily dissolved on the electrodes by the chlo- Iine-containing hydrochloric acid formed by diffusion of chlorine from the chlorine-containing hydrochloric acid of the anode space through the diaphragm into the acid of the cathode space. This process may be promoted by allowing further chlorine-containing hydrochloric acid to travel from the anode space through the diaphragm into the cathode space.
  • the metal separates again as active layer on the cathode.
  • the solution containing palladium salt can be collected in a separate vessel and subsequently added in portions to the electrolyte. Still further, it is possible to separate the palladium from the solution in the form of metal by a conventional method.
  • the process according to the invention offers the particular advantage that parts of the layer dropping from the cathode during operation dissolve in the acid of the cathode space.
  • the latter always contains a small amount of chlorine because of the diffusion through the diaphragm. It is thus not necessary to work up the inactive cathode sludge.
  • the activity of the palladium layer produced is appreciably greater than that of the metals hitherto used for this purpose.
  • Example 3 The electrolytic cell used was-composed of 14 seriesconnected individual cells with bipolar electrodes between which a plastic diaphragm was inserted to separate the developed gases.
  • the cathode and anode surface of the individual cell was 2.5 square meters, and the total cathode surface 35 square meters.
  • 200 liters per hour of hydrochloric acid of about 23% strength were introduced in each cell into the space between anode and diaphragm or cathode and diaphragm, respectively.
  • the gases developed during electrolysis and the depleted hydrochloric acid of about 20% strength by weight were withdrawn .at the head of the cell and separated from the liquid via siphons.
  • the acids from the anode and cathode spaces were readjusted with hydrogen chloride to a content of about 23% strength by weight and recycled into the anode and cathode spaces.
  • metal salt is a salt of palladium added in an amount providing from 0.2 to 2 grams of palladium per square meter of active electrode surface.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (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)
US401922A 1964-06-16 1964-10-06 Reducing the excess voltage in electrolysis of aqueous hydrochloric acid in diaphragm cells Expired - Lifetime US3336209A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEF43184A DE1216852B (de) 1964-06-16 1964-06-16 Verfahren zur Elektrolyse von waessriger Salzsaeure in Diaphragmenzellen

Publications (1)

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US3336209A true US3336209A (en) 1967-08-15

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US401922A Expired - Lifetime US3336209A (en) 1964-06-16 1964-10-06 Reducing the excess voltage in electrolysis of aqueous hydrochloric acid in diaphragm cells

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US (1) US3336209A (US06826419-20041130-M00005.png)
BE (1) BE653975A (US06826419-20041130-M00005.png)
DE (1) DE1216852B (US06826419-20041130-M00005.png)
NL (1) NL6412142A (US06826419-20041130-M00005.png)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5418497A (en) * 1977-07-11 1979-02-10 Ppg Industries Inc Electrolysis method
US4182662A (en) * 1979-07-12 1980-01-08 Energy Development Associates, Inc. Method of forming hydrogen
US4288301A (en) * 1978-07-19 1981-09-08 Energy Development Associates, Inc. Method of forming hydrogen
US4426269A (en) 1978-03-04 1984-01-17 The British Petroleum Company Limited Method of stabilizing electrodes coated with mixed oxide electrocatalysts during use in electrochemical cells
EP4335947A1 (en) 2022-09-06 2024-03-13 Covestro Deutschland AG Method and system for operating an electrochemical reactor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3102306A1 (de) * 1980-02-02 1982-01-14 Basf Ag, 6700 Ludwigshafen Elektroden
DE4417744C1 (de) * 1994-05-20 1995-11-23 Bayer Ag Verfahren zur Herstellung stabiler Graphitkathoden für die Salzsäureelektrolyse und deren Verwendung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2666024A (en) * 1949-04-22 1954-01-12 Fmc Corp Oxidation and chlorine recovery process
US3129152A (en) * 1959-08-12 1964-04-14 Hoechst Ag Process for the electrolytic recovery of chlorine from hydrogen chloride or hydrochloric acid

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2666024A (en) * 1949-04-22 1954-01-12 Fmc Corp Oxidation and chlorine recovery process
US3129152A (en) * 1959-08-12 1964-04-14 Hoechst Ag Process for the electrolytic recovery of chlorine from hydrogen chloride or hydrochloric acid

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5418497A (en) * 1977-07-11 1979-02-10 Ppg Industries Inc Electrolysis method
US4426269A (en) 1978-03-04 1984-01-17 The British Petroleum Company Limited Method of stabilizing electrodes coated with mixed oxide electrocatalysts during use in electrochemical cells
US4288301A (en) * 1978-07-19 1981-09-08 Energy Development Associates, Inc. Method of forming hydrogen
US4182662A (en) * 1979-07-12 1980-01-08 Energy Development Associates, Inc. Method of forming hydrogen
EP4335947A1 (en) 2022-09-06 2024-03-13 Covestro Deutschland AG Method and system for operating an electrochemical reactor
WO2024052195A1 (en) 2022-09-06 2024-03-14 Covestro Deutschland Ag Method and system for operating an electrochemical reactor

Also Published As

Publication number Publication date
NL6412142A (US06826419-20041130-M00005.png) 1965-12-17
BE653975A (US06826419-20041130-M00005.png) 1965-04-05
DE1216852B (de) 1966-05-18

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