US3219563A - Multi-electrolytic cell comprising a plurality of diaphragm-free unit cells and the use of same for preparing alkali metal chlorates - Google Patents

Multi-electrolytic cell comprising a plurality of diaphragm-free unit cells and the use of same for preparing alkali metal chlorates Download PDF

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US3219563A
US3219563A US114354A US11435461A US3219563A US 3219563 A US3219563 A US 3219563A US 114354 A US114354 A US 114354A US 11435461 A US11435461 A US 11435461A US 3219563 A US3219563 A US 3219563A
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cell
anode
cathode
unit
alkali metal
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US114354A
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English (en)
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Collins John Hardie
Edwards George Ernest
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Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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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
    • C25B1/265—Chlorates
    • 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
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material

Definitions

  • the present invention relates to improvements in or relating to mold-electrolytic cells. More particularly it relates to multi-electroiytic cells, comprising a plurality of unit electrolytic cells, for the manufacture of alkali metal chlorates from aqueous solutions of alkali metal chlorides.
  • the pH of the electrolyte in cells producing chlorates is relatively high so that oxidation of the graphite by discharge of hydroxyl ions is severe.
  • High rates of wear lead not only to heavy replacement costs for anodes but also to progressively increasing cell voltage, because of the increasing anode-cathode gap, and thus to excessive energy consumption.
  • the maximum anode current density achievable with an acceptable rate of anode wear is limited to about 1.5 kA/m. even when steps are taken to cool the cell and when cooling is not resorted to the anode current density may be as low as 0.2-0.5 kA/m.
  • the anode in each unit cell of the multielectrolytic cell may be, inter alia, a layer of a platinum metal, namely ruthenium, rhodium, palladium, osmium, iridium or platinum, or an alloy of two or more of such metals, which is on one side of each titanium metal sheet partition.
  • the cathode should comprise a layer of a platinum metal, which may be applied to the titanium metal sheet by any of the methods disclosed in the aforementioned British application, since we have found that a platinum metal cathode layer minimises the cell voltage needed and does not sutter from the corrosion found with iron and steel cathode layers when the cell is taken off load. It is also preferred that the anode layer of the platinum metal in each unit cell should be electrolytically deposited on the titanium surface since such an electrolytically deposited layer of the platinum metal provides the lowest and most stable cell voltage.
  • the gap between anode and cathode may advantageously be made very narrow, suitably about 3 mm., thus further assisting in the reduction of cell voltage.
  • alkali metal chlorate is produced by electrolysis of alkali metal chloride solution according to the present invention a current density approximately 3-14 times greater than in prior art chlorate cells fitted with graphite, magnetite or platinum anodes may be employed at high energy efficiency.
  • a current density approximately 3-14 times greater than in prior art chlorate cells fitted with graphite, magnetite or platinum anodes may be employed at high energy efficiency.
  • the energy consumption is at least as low as in the prior art low-current-density chlorate cells.
  • anode is a layer of a platinum metal on one side of the titanium metal sheet separator and there is no diaphragm between anode and cathode, which is characterised in that the current density employed is at least 2 lcA/m. and preferably between 2 and 4 kA/mP.
  • a platinum metal is meant a noble metal of the platinum group or an alloy of two or more such metals as defined in British application Serial No. 845,043.
  • electrolysis may be carried out continuously, an aqueous solution containing alkali metal chloride being passed through the cell at high temperature, suitably 7080' C., and the eflluent liquors may be cooled or concentrated to promote crystallisation of the chlorate produced in the cell. It is preferred to have a small concentration of a chromate in the liquor fed to the cell, suitably 2-10 g./l. of an alkali metal chromate, in order to promote chlorate production as is known in the art.
  • An especially advantageous meth od which is made possible because of the high electrolyte temperatures which can be employed in the present process, is to operate the cell in conjunction with a continuous crystallisation and resaturation system, whereby the chlorate is recovered without recourse to evaporation and simply by cooling the cell efiiuent liquor, and the liquor is subsequently resaturated with alkali metal chloride and reheated for return to the cell.
  • the temperature at which resaturation is carried out will depend on the solubility relations of the salts involved. For example, when manufacturing sodium chlorate the resaturation with sodium chloride is best carried out at elevated temperature, suitably about 70 C.
  • the crystalliser may be operated at about 20 C.
  • resaturation must be carried out at a lower temperature because of the steeper solubility curve for potassium chloride, otherwise on cooling the cell effluent liquor for crystallisation of potassium chlorate sufficient potassium chloride may still be present in solution to deposit this salt along with the chlorate in the crystalliser.
  • the potassium salt it is convenient to carry out resaturation at the crystalliser temperature, suitably about 20 C., and then to reheat the resaturated liquor before return to the cell. Heat may be conserved by operating the cooling/ crystallising-resaturation/ reheating cycle on the heat-exchanger principle.
  • FIG. 1 shows schematically (not to scale) in vertical cross section one form of multielectrolytic cell according to the invention.
  • FIG. 2 shows one arrangement of apparatus suitable for carrying out the process according to the invention for the manufacture of sodium chlorate on the aforementioned continuous resaturation principle.
  • the multielectrolytic cell is shown as comprising seven unit electrolytic cells 1 but it must be understood that it may comprise a smaller or larger number of unit cells.
  • the multielectrolytic cell has titanium end plates 2 and 3, and between each pair of unit cells 1 are titanium sheet metal partitions 4.
  • Anodes are thin layers of a platinum metal carried on the internal surface of end plate 2 and on one face of each of titanium partitions 4.
  • Cathodes 6 are preferably thin layers of a platinum metal on the internal surface of end plate 3. and on the face of each of the titanium partitions 4 opposite to the anodes.
  • Cathode layers 6 may however be layers of iron or steel or may be omitted entirely so that the bare titanium faces of end plate 3 and partitions 4 form. the working cathode surfaces.
  • the anodes 5 and cathodes 6 are spaced apart at a distance of approximately 3 mm. from each other by insulating separators 7 and 8 placed between the ends of each pair of titanium sheets, the whole assembly of sheets and insulating separators being held together in a liquorand gas-tight manner by clamping means (not shown).
  • Channels 9, passing through the lower set of insulating separators 7, are used for feeding electrolyte to each unit cell, and channels 10, passing through the upper set of insulating separators 8, are used for removing the electrolyte and hydrogen gas from each unit cell.
  • the electrolyte may alternatively be fed to and removed from the unit cells in some other manner, for example through channels cut in the titanium end plates 2 and 3 and titanium partitions 4 near the bottom and top respectively.
  • 11 and 12 are current leads to the anodic and cathodic titanium end plates 2 and 3 respectively.
  • FIG. 2 is a multielectrolytic cell of the type shown in FIG. 1 comprising, in the case shown, seven unit electrolytic cells 1.
  • feed electrolyte is saturated with sodium chloride at a temperature of approximately 70 C. in saturator 14 and passes continuously from 14 by lines 9 to each of the unit cells 1, where sodium chlorate and hydrogen are produced by electrolysis.
  • Spent electrolyte leaves unit cells 1 by lines together with the hydrogen evolved in the cells.
  • Hydrogen is removed at 15 and spent electrolyte passes along line 16, is cooled in heat exchanger 17 and then flows through crystalliser 18, where sodium chlorate crystals are deposited.
  • Line 21 is provided for a secondary flow of spent electrolyte from the cells 1 to the saturator 14 without passing through the crystalliser as a means of adjusting the chloride/ chlorate content of the electrolyte entering and leaving the cells.
  • the flow through line 21 is controlled by valve 22. It Will be understood from the foregoing discussion that the apparatus shown in FIG. 2 may also be employed for the continuous production of potassium chlorate provided that the heating means are repositioned so that the saturator works at low temperature and the saturated electrolyte is afterwards heated before being fed to the cells.
  • the following table illustrates the efficient production of sodium and potassium chlorates by the process according to the invention.
  • the anodes were electrodeposited layers of platinum and the cathodes were layers of platinum deposited by the painting and firing process as practised in the ceramic industry.
  • a process for the manufacture of alkali metal chlorate by the electrolysis of an aqueous solution of alkali metal chloride which comprises uses a multi-electrolytic cell having a plurality of diaphragm-free unit electrolytic cells, each of said cells having an anode and a cathode with the cells arranged so that a partition carries the anode of each cell and the cathode of the next cell, said partition comprising an inert titanium metal sheet separating the anode of one unit electrolytic cell from the cathode of an adjacent unit electrolytic cell, the anode in each unit cell comprising a layer of a platinum metal on one side of the titanium metal and the cathode in said unit cell comprising a layer of a metal selected from the group consisting of a platinum metal, iron and steel on the side of the next titanium metal sheet opposed to the anode of said unit cell, and employing an anode current density of at least 2 kA/m.
  • a process for the manufacture of alkali metal chlorate by the electrolysis of an aqueous solution of alkali metal chloride which comprises employing an anode current density of at least 2 kA/m. in a diaphragm-free, multielectrolytic cell, said cell comprising a plurality of diaphragm-free unit electrolytic cells, each such unit cell having an anode and a cathode, the unit cells being so arranged that a partition carries the anode of each unit cell and the cathode of the next cell, said partition comprising an inert titanium metal sheet, the anode of each cell comprising a layer of a platinum metal on one side of the titanium separating sheet and the cathode of said unit cell being the bare titanium face of the next titanium metal sheet facing the anode in said unit cell and carrying the anode for the adjacent unit cell.
  • a multielectrolytic cell comprising a plurality of diaphragm-free unit electrolytic cells, each of said cells having an anode and a cathode with the cells arranged so that a partition carries the anode of each cell and the cathode of the next cell, said partition comprising an inert titanium metal sheet separating the anode of one unit electrolytic cell from the cathode of an adjacent unit electrolytic cell but in electrical conducting relationship with respect to both the anode and the cathode carried thereby, the anode in each unit cell comprising a layer of a platinum metal on one side of the titanium metal sheet and the cathode in said unit cell comprising a layer of a metal selected from the group consisting of a platinum metal, iron and steel on the side of the next titanium metal sheet opposed to the anode of said unit cell.
  • a multielectrolytic cell comprising a plurality of diaphragm-free unit electrolytic cells, each of said cells having an anode and a cathode with the cells arranged so that a partition carries the anode of each cell and the cathode of the next cell, said partition comprising an inert titanium metal sheet separating the anode of one unit electrolytic cell from the cathode of an adjacent unit electrolytic cell but in electrical conducting relationship with respect to both the anode and the cathode carried thereby, the anode in each unit cell comprising a layer of a platinum metal on one side of the titanium metal sheet and the cathode in said unit cell comprising a layer of a platinum metal on the side of the next titanium metal sheet opposed to the anode of said unit cell.

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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)
  • Inorganic Chemistry (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Electrolytic Production Of Metals (AREA)
US114354A 1960-06-22 1961-06-02 Multi-electrolytic cell comprising a plurality of diaphragm-free unit cells and the use of same for preparing alkali metal chlorates Expired - Lifetime US3219563A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB21851/60A GB905749A (en) 1960-06-22 1960-06-22 Improvements in or relating to multi-electrolytic cells

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US3219563A true US3219563A (en) 1965-11-23

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US (1) US3219563A (en, 2012)
CH (1) CH457375A (en, 2012)
ES (1) ES268425A1 (en, 2012)
FR (2) FR1220408A (en, 2012)
GB (1) GB905749A (en, 2012)
NL (2) NL266134A (en, 2012)
SE (1) SE316748B (en, 2012)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3324024A (en) * 1961-08-10 1967-06-06 Staveley Iron & Chemical Compa Cell for making alkali metal chlorates
US3463722A (en) * 1964-04-24 1969-08-26 Chemech Eng Ltd Electrolysis system for chlorate manufacture
US3464901A (en) * 1965-11-30 1969-09-02 Hooker Chemical Corp Production of chlorates
US3539486A (en) * 1966-09-14 1970-11-10 Krebs & Co Ag Method of electrolytically producing alkaline chlorates
US3919059A (en) * 1973-03-01 1975-11-11 Ppg Industries Inc Electrolytic cell
US3974058A (en) * 1974-09-16 1976-08-10 Basf Wyandotte Corporation Ruthenium coated cathodes
US4123339A (en) * 1975-02-07 1978-10-31 Andco Industries, Inc. Method and apparatus for electrochemical contaminant removal from liquid media
US4124480A (en) * 1976-02-17 1978-11-07 Paterson Candy International, Limited Bipolar cell
US4839004A (en) * 1987-02-27 1989-06-13 Castellini, S.P.A. Method and an apparatus for cold sterilization of surgical instruments, in particular dental surgery instruments
CN1042842C (zh) * 1993-05-31 1999-04-07 谭秉彝 电解食盐生产氯酸钠的方法

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113918A (en) * 1959-06-03 1963-12-10 Evans David Johnson Electrolytic apparatus
US3103484A (en) * 1959-10-10 1963-09-10 Anodes for electrolytic chlorine
US3483568A (en) * 1966-12-12 1969-12-16 Continental Copper & Steel Ind Electrolytic metal extraction
DE2148337A1 (de) * 1971-09-28 1973-04-05 Uhde Gmbh Friedrich Bipolare mehrfach-elektrolysezelle mit diaphragma
CA2760094C (en) * 2009-05-15 2018-03-20 Akzo Nobel Chemicals International B.V. Activation of cathode

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE569500A (en, 2012) * 1957-07-17
US665426A (en) * 1895-09-09 1901-01-08 Nat Electrolytic Company Art of obtaining chlorates by electrolysis.
US1023545A (en) * 1911-06-12 1912-04-16 Harry H Bates Electrolytic process.
US2511516A (en) * 1945-10-31 1950-06-13 Western Electrochemical Compan Process for making sodium chlorate
US2628935A (en) * 1946-06-05 1953-02-17 Pennsylvania Salt Mfg Co Electrolytic production of chlorates
US2765201A (en) * 1953-03-16 1956-10-02 Clay E Phillips Ceiling jacks
US2813825A (en) * 1955-12-14 1957-11-19 Pennsalt Chemicals Corp Method of producing perchlorates
GB845043A (en) * 1958-03-18 1960-08-17 Ici Ltd Improvements in or relating to multi-electrolytic cells
US3043757A (en) * 1959-07-08 1962-07-10 Olin Mathieson Electrolytic production of sodium chlorate

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US665426A (en) * 1895-09-09 1901-01-08 Nat Electrolytic Company Art of obtaining chlorates by electrolysis.
US1023545A (en) * 1911-06-12 1912-04-16 Harry H Bates Electrolytic process.
US2511516A (en) * 1945-10-31 1950-06-13 Western Electrochemical Compan Process for making sodium chlorate
US2628935A (en) * 1946-06-05 1953-02-17 Pennsylvania Salt Mfg Co Electrolytic production of chlorates
US2765201A (en) * 1953-03-16 1956-10-02 Clay E Phillips Ceiling jacks
US2813825A (en) * 1955-12-14 1957-11-19 Pennsalt Chemicals Corp Method of producing perchlorates
BE569500A (en, 2012) * 1957-07-17
GB845043A (en) * 1958-03-18 1960-08-17 Ici Ltd Improvements in or relating to multi-electrolytic cells
US3043757A (en) * 1959-07-08 1962-07-10 Olin Mathieson Electrolytic production of sodium chlorate

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3324024A (en) * 1961-08-10 1967-06-06 Staveley Iron & Chemical Compa Cell for making alkali metal chlorates
US3463722A (en) * 1964-04-24 1969-08-26 Chemech Eng Ltd Electrolysis system for chlorate manufacture
US3464901A (en) * 1965-11-30 1969-09-02 Hooker Chemical Corp Production of chlorates
US3539486A (en) * 1966-09-14 1970-11-10 Krebs & Co Ag Method of electrolytically producing alkaline chlorates
US3919059A (en) * 1973-03-01 1975-11-11 Ppg Industries Inc Electrolytic cell
US3974058A (en) * 1974-09-16 1976-08-10 Basf Wyandotte Corporation Ruthenium coated cathodes
US4123339A (en) * 1975-02-07 1978-10-31 Andco Industries, Inc. Method and apparatus for electrochemical contaminant removal from liquid media
US4124480A (en) * 1976-02-17 1978-11-07 Paterson Candy International, Limited Bipolar cell
US4839004A (en) * 1987-02-27 1989-06-13 Castellini, S.P.A. Method and an apparatus for cold sterilization of surgical instruments, in particular dental surgery instruments
CN1042842C (zh) * 1993-05-31 1999-04-07 谭秉彝 电解食盐生产氯酸钠的方法

Also Published As

Publication number Publication date
DE1417787B2 (de) 1972-07-20
FR80106E (fr) 1963-03-15
NL266134A (en, 2012) 1964-07-10
SE316748B (en, 2012) 1969-11-03
CH457375A (de) 1968-06-15
NL129923C (en, 2012) 1970-11-16
DE1417787A1 (de) 1968-10-10
ES268425A1 (es) 1961-12-16
FR1220408A (fr) 1960-05-24
GB905749A (en) 1962-09-12

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