EP0463739A1 - Vielzahl von Elektrolysezellen enthaltende Vorrichtung - Google Patents

Vielzahl von Elektrolysezellen enthaltende Vorrichtung Download PDF

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Publication number
EP0463739A1
EP0463739A1 EP91304853A EP91304853A EP0463739A1 EP 0463739 A1 EP0463739 A1 EP 0463739A1 EP 91304853 A EP91304853 A EP 91304853A EP 91304853 A EP91304853 A EP 91304853A EP 0463739 A1 EP0463739 A1 EP 0463739A1
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EP
European Patent Office
Prior art keywords
cells
electrolytic cells
electrolytic
cell
headers
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Withdrawn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
EP91304853A
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English (en)
French (fr)
Inventor
Michael Frederick Dutton
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.)
Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Publication of EP0463739A1 publication Critical patent/EP0463739A1/de
Withdrawn legal-status Critical Current

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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
    • C25B15/00—Operating or servicing cells
    • 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
    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes

Definitions

  • This invention relates to an apparatus comprising a plurality of electrolytic cells.
  • Electrolytic cells are used to produce a wide variety of chemical products by electrolysis of suitable electrolytes.
  • many electroor- ganic syntheses are practised industrially but the primary industrial use of electrolytic cells for the production of chemical products is in the electrolysis of aqueous solutions of alkali metal halides.
  • aqueous solutions are electrolysed on a vast scale throughout the world to produce chlorine, hydrogen and aqueous caustic alkali solutions, eg aqueous sodium chloride solution is electrolysed to produce aqueous sodium hydroxide solution, chlorine, and hydrogen, and aqueous potassium hydroxide solution is electrolysed to produce aqueous potassium hydroxide solution, chlorine and hydrogen.
  • Such solutions are also electrolysed on a large scale to produce aqueous alkali metal chlorate solutions.
  • Electrolytic cells in which such electrolyses are carried out generally comprise a plurality of anodes and cathodes with each anode generally being separated from the adjacent cathode by a separator which divides the electrolytic cell into a plurality of anode and cathode compartments, although in an electrolytic cell for the production of alkali metal chlorate the cell is undivided.
  • the anode compartments of such a cell are provided with means for feeding electrolyte to the cell, suitably from a common header, and with means for removing products of electrolysis from the cell suitably via a common header or headers.
  • the cathode compartments of the cell are provided with means for removing electrolysis products from the cell suitably via a common header or headers, and optionally with means for feeding water or other fluid to the cell, suitably from common headers.
  • the electrolytic cells may be of the diaphragm or membrane type.
  • a diaphragm type cell the separators positioned between adjacent anodes and cathodes are microporous and in use the electrolyte passes through the diaphragms from the anode compartments to the cathode compartments of the cell.
  • a membrane type cell the separators are essentially hydraulically impermeable and in use ionic species are transported across the membranes between the anode compartments and the cathode compartments of the cell.
  • an aqueous alkali metal chloride solution is electrolysed in an electrolytic cell of the diaphragm type the solution is fed to the anode compartments of the cell suitably from a common header, chlorine which is produced in the electrolysis is removed from the anode compartments of the cell via a common header, the alkali metal chloride solution passes through the diaphragms and hydrogen and alkali metal hydroxide produced by electrolysis are removed from the cathode compartments via a common header or headers, the alkali metal hydroxide being removed in the form of an aqueous solution of alkali metal chloride and alkali metal hydroxide.
  • an aqueous alkali metal chloride solution is electrolysed in an electrolytic cell of the membrane type
  • the solution is fed to the anode compartments of the cell suitably from a common header and chlorine produced in the electrolysis and depleted alkali metal chloride solution are removed from the anode compartments via a common header or headers
  • alkali metal ions are transported across the membranes to the cathode compartments of the cell to which water or dilute aqueous alkali metal hydroxide solution may be fed from a common header, and hydrogen and alkali metal hydroxide solution produced by the reaction of alkali metal ions with water are removed from the cathode compartments of the cell via a common header or headers.
  • the electrolytic cells may comprise a large number of anodes and cathodes, particularly where the cells are of the filter press type, eg the cells may contain as many as fifty or more anodes and cathodes.
  • the cells may also be of the monopolar or of the bipolar type.
  • a monopolar type cell a plurality of anodes and cathodes are positioned alternately and a separator, when present, is positioned between each anode and adjacent cathode.
  • a bipolar type cell comprises a plurality of electrodes each having an anode face and a cathode face and a separator, when present, is positioned between an anode face of an electrode and a cathode face of an adjacent electrode.
  • chlorine and depleted alkali metal chloride solution produced in the electrolysis will generally be removed from the anode compartments of the cell via a common header or headers and hydrogen and aqueous alkali metal hydroxide solution produced in the electrolysis will generally be removed from the cathode compartments via a common header or headers for each of these products.
  • an apparatus comprising a plurality of electrolytic cells, a header from which electrolyte may be charged to the electrolytic cells and a header or headers via which a product or products of electrolysis may be removed from the electrolytic cells, and an electrical circuit to which the electrolytic cells are connected and by means of which electrical power may be fed to the electrolytic cells, in which the electrolytic cells are arranged in two or more groups of cells and the apparatus comprises a plurality of headers from which different electrolytes may be charged to electrolytic cells in the different groups of cells, and a plurality of headers via which different products of electrolysis may be removed from specific electrolytic cells in the different groups of cells.
  • the apparatus may comprise a single electrical circuit to which a plurality of electrolytic cells or even all of the electrolytic cells in the groups of cells are connected.
  • This is of course conventional practice in a cell room which comprises a plurality of electrolytic cells.
  • the novelty and in- ventivity of the present apparatus resides in the arrangement of headers in the apparatus.
  • electrolyte is charged from a single common header to all of the electrolytic cells in a group of cells such that the group of cells may be used for the electrolysis of one electrolyte at any one time, eg it may be used for the electrolysis of aqueous sodium chloride solution, or aqueous potassium chloride solution, but both solutions may not be electrolysed in the group of cells at the same time.
  • the apparatus will of course be necessary for the apparatus to comprise a corresponding number of headers from which different electrolytes may be charged to the electrolytic cells and to which different products of electrolysis may be charged to and via which these products may be removed from the cells.
  • the apparatus will generally comprise two groups of cells.
  • the apparatus will be described with reference to the simultaneous electrolysis of aqueous solutions of sodium chloride and potassium chloride in the apparatus.
  • the electrolytic cells will be connected to an electrical circuit, the apparatus will comprise two headers from one of which aqueous sodium chloride solution may be charged to one group of cells and from the other of which aqueous potassium chloride solution may be charged to the other group of cells.
  • a product or products of electrolysis which are produced during electrolysis in both groups of electrolytic cells may be passed to a common header or headers for all of the cells but the apparatus will comprise two headers to one of which aqueous sodium hydroxide solution will be passed and to the other of which aqueous potassium hydroxide solution will be passed.
  • the apparatus will comprise two headers to one of which aqueous sodium hydroxide solution will be passed and to the other of which aqueous potassium hydroxide solution will be passed.
  • the electrolytic cells in the apparatus may have any suitable construction as the invention does not reside in the particular type of cells to be used in the apparatus.
  • the cells may be monopolar cells or they may be bipolar cells, and the cells may be fitted with separators positioned between each anode and adjacent cathode in a monpolar cell or between an anode of a bipolar electrode and a cathode of an adjacent bipolar electrode in a bipolar cell.
  • a suitable separator for use as a diaphragm in asbestos or microporous sheet of a polymeric material resistant to chemical attack, eg polytetrafluoroethylene, although other materials which may be used include, for example, tetrafluoroethylene-hexafluoropropylene copolymers, vinylidene fluoride polymers and copolymers, and fluorinated ethylene-propylene copolymers.
  • a suitable material for use as an ion-exchange membrane is a fluorine-containing polymeric material containing cation-exchange groups, for example, sulphonic acid, carboxylic acid or phosphonic acid groups, or derivatives thereof, or a mixture of two or more such groups.
  • Suitable cation-exchange membranes are those described, for example, in UK Patents Nos 1184321, 1402920, 1406673, 1455070, 1497748, 1497749,1518387 and 1531068.
  • a suitable material for use as an anode is a film-forming metal or an alloy thereof, for example zircoium, niobium, tungsten or tantalum, but preferably of titanium, and the surface of the anode suitably carries a coating of an electro-conducting electrocatalytically active material.
  • the coating may comprise one or more platinum group metals, that is platinum, rhodium, iridium, ruthenium, osmium or palladium, and/or an oxide of one or more of these metals.
  • the coating of platinum group metal and /or oxide may be present in admixture with one or more non-noble metal oxides, particularly one or more film-forming metal oxides, e.g. titanium dioxide.
  • Electro-conducting electrocatalytically active materials for use as anode coatings in an electrolytic cell for the electrolysis of aqueous alkali metal chloride solution, and methods of application of such coatings, are well known in the art.
  • a suitable material for use as a cathode is iron or steel or nickel.
  • the cathode may be coated with a material designed to reduce the hydrogen overpotential of the electrolysis.
  • the electrolytic cells in the group thereof may be substantially the same. However, this is not necessarily so.
  • the nature of the separator in the electrolytic cells may vary depending on the nature of the electrolyte which is to be electrolysed.
  • the membranes in those cells in which aqueous sodium chloride solution is to be electrolysed may be different from the ion-exchange membranes in those cells in which aqueous potassium chloride solution is to be electrolysed, although some cells may be used to electrolyse different electrolytes.
  • the cells In order that individual electrolytic cells in the groups thereof may readily be changed in response to changing production requirements and replaced by cells more suitable for satisfying the changing production requirements it is preferred that the cells, and preferably each cell, is provided with means for readily shorting out the cells from the electrical circuit so that it can be removed and replaced by another electrolytic cell. Furthermore, in order to facilitate removal and replacement of electrolytic cells it is preferred that the cells are readily detached from and reattached to the appropriate headers.
  • electrolyses may be carried out in the same electrolytic cell and all that is required when a change is made in the electrolysis which is to be carried out is for the cell to be detached from one header or headers and attached to a different header or headers. It may be necessary also to flush out the cell when the nature of the electrolyte is changed and prior to commencing electrolysis with a different electrolyte.
  • the apparatus of the present invention is simple in concept but provides substantial benefits in operation, and in particular it provides a plurality of electrolytic cells the use of which may readily be adapted to suit changing production requirements.
  • the apparatus is readily able to cope, for example, with an increased demand for aqueous potassium hydroxide solution at the expense of aqueous sodium hydroxide solution, and vice versa.
  • FIG. 1 is a diagrammatic representation of an apparatus comprising a plurality of electrolytic cells, and for the purposes of illustration the apparatus will be described with reference to a group of electrolytic cells in which aqueous sodium chloride solution is electrolysed and with reference to a group of electrolytic cells in which aqueous potassium chloride solution is electrolysed.
  • the apparatus comprises a plurality of monopolar electrolytic cells (1 to 10) each of which comprises a plurality of anodes and cathodes and in which each anode is separated from an adjacent cathode by a cation-exchange membrane which provide in each of the electrolytic cells a plurality of anode compartments and cathode compartments.
  • Each of the electrolytic cells is connected to a common electrical circuit 11.
  • the apparatus comprises a plurality of headers 12 to 21, headers 12 to 17 being connected to electrolytic cell 1 by means of lines 22 to 27 respectively and electrolytic cell 6 being connected to headers 16 to 21 by means of lines 28 to 33 respectively.
  • Electrolytic cells 2 to 5 are connected to the headers in the same manner as cell 1 and form with cell 1 a first group of cells, and elec- trolytc cells 7 to 10 are connected to the headers in the same manner as cell 6 and form with cell 6 a second group of cells.
  • the headers 12 to 21 served the following functions.
  • aqueous NaCl solution and dilute aqueous NaOH solution are charged to electrolytic cell 1 and to cells 2 to 5 from headers 12 and 14 via lines 22 and 24 respectively, and depleted aqueous NaCl solution, aqueous NaOH solution, chlorine and hydrogen are passed to headers 13, 15, 16, 17 via lines 23, 25, 26, 27 respectively.
  • Aqueous KCI solution and dilute aqueous KOH solution are charged to electrolytic cell 6 and to cells 7 to 10 from headers 18 and 20 via lines 30 and 32 respectively, and depleted aqueous KCI solution, aqueous KOH solution, chlorine and hydrogen are passed to headers 19, 21, 16, 17 via lines 31, 33, 28 29 respectively.
  • the apparatus comprises only one chlorine header and one hydrogen header to which chlorine and hydrogen produced in both the group of electrolytic cells 1 to 5 and in the group of electrolytic cells 6 to 10 is passed.
  • one or more of the electrolytic cells in the group of cells 6 to 10 may be connected to the headers 12, 14, 13 and 15.

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  • 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)
EP91304853A 1990-06-15 1991-05-29 Vielzahl von Elektrolysezellen enthaltende Vorrichtung Withdrawn EP0463739A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9013472 1990-06-15
GB909013472A GB9013472D0 (en) 1990-06-15 1990-06-15 Apparatus comprising a plurality of electrolytic cells

Publications (1)

Publication Number Publication Date
EP0463739A1 true EP0463739A1 (de) 1992-01-02

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP91304853A Withdrawn EP0463739A1 (de) 1990-06-15 1991-05-29 Vielzahl von Elektrolysezellen enthaltende Vorrichtung

Country Status (4)

Country Link
EP (1) EP0463739A1 (de)
JP (1) JPH0598485A (de)
GB (2) GB9013472D0 (de)
ZA (1) ZA914244B (de)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135314A1 (de) * 1983-08-15 1985-03-27 Imperial Chemical Industries Plc Elektrolytischer Zellenmodul

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135314A1 (de) * 1983-08-15 1985-03-27 Imperial Chemical Industries Plc Elektrolytischer Zellenmodul

Also Published As

Publication number Publication date
JPH0598485A (ja) 1993-04-20
GB9013472D0 (en) 1990-08-08
GB9111475D0 (en) 1991-07-17
ZA914244B (en) 1992-06-24

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