WO2012084765A1 - Procédé électrolytique - Google Patents

Procédé électrolytique Download PDF

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Publication number
WO2012084765A1
WO2012084765A1 PCT/EP2011/073167 EP2011073167W WO2012084765A1 WO 2012084765 A1 WO2012084765 A1 WO 2012084765A1 EP 2011073167 W EP2011073167 W EP 2011073167W WO 2012084765 A1 WO2012084765 A1 WO 2012084765A1
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WO
WIPO (PCT)
Prior art keywords
chromium
added
chlorate
process according
compound
Prior art date
Application number
PCT/EP2011/073167
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English (en)
Inventor
Kristoffer Hedenstedt
Rolf Edvinsson Albers
Original Assignee
Akzo Nobel Chemicals International B.V.
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Filing date
Publication date
Application filed by Akzo Nobel Chemicals International B.V. filed Critical Akzo Nobel Chemicals International B.V.
Priority to BR112013015155-2A priority Critical patent/BR112013015155A2/pt
Priority to EA201390875A priority patent/EA025314B1/ru
Priority to US13/996,686 priority patent/US20130292261A1/en
Priority to CA2821309A priority patent/CA2821309A1/fr
Priority to EP11802908.1A priority patent/EP2655692A1/fr
Publication of WO2012084765A1 publication Critical patent/WO2012084765A1/fr

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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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/14—Alkali metal compounds
    • 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

Definitions

  • the present invention relates to a process of producing alkali metal chlorate in an electrolytic cell comprising an anode and a cathode, wherein substantially no hexavalent chromium is added to the process from an external source.
  • hexavalent chromium In the electrolysis of sodium chloride to form sodium chlorate, hexavalent chromium, usually sodium dichromate, is conventionally added to the electrolyte introduced into the cell to improve the current efficiency of the cell in the conversion of sodium chloride to sodium chlorate. This is partly obtained by suppressing the reduction of hypochlorite and chlorate at the cathode.
  • EP 266 128 discloses a process of producing chlorate by diaphragmaless electrolysis. In this process, hexavalent chromium is added to the process from an external source.
  • Hexavalent chromium is mutagenic, reprotoxic, and carcinogenic and thus highly poisonous. There is thus a problem involved in the handling of hexavalent chromium including introduction thereof to the electrolytic cell from an external source. Therefore, strict safety precautions are a prerequisite. Hexavalent chromium also functions as a buffering solution in the chlorate electrolyte.
  • One object of the present invention is to provide an environmentally adapted process which obviates handling problems involved when introducing substantial amounts of toxic chromium(VI) compounds into an electrolytic cell from an external source while safeguarding appropriate process conditions are maintained.
  • one object is to obviate transportation of highly toxic hexavalent chromium.
  • a further object of the invention is to provide an alternative compound entirely substituting or to a large extent substituting toxic chromium(VI) compounds as raw material.
  • the present invention intends to provide a process which safeguards a controlled supply of hexavalent chromium in the cell electrolyte which is independent on the amount of for example hypochlorite in condensate streams.
  • a further intention is to provide a process which facilitates production of alkali metal chlorate wherein hexavalent chromium can be provided at an acidic pH whereby necessary pH adjustment can be reduced or eliminated.
  • a further intention of the instant invention is to provide a process which rapidly provides hexavalent chromium.
  • the present invention relates to a process of producing alkali metal chlorate in an electrolytic cell comprising an anode and a cathode, wherein at least one chromium compound having a valence lower than +6 is added to the process, wherein said at least one chromium compound is oxidized to hexavalent chromium within said process, and wherein substantially no hexavalent chromium is added to the process from an external source.
  • the process of producing alkali metal chlorate comprises introducing an electrolyte solution containing alkali metal chloride and alkali metal chlorate to an electrolytic cell, electrolyzing the electrolyte solution to produce an electrolyzed chlorate solution, transferring the electrolysed chlorate solution to a chlorate reactor to react the electrolysed chlorate solution further to produce a more concentrated alkali metal chlorate electrolyte.
  • the main anode reaction is chlorine formation
  • the main cathode reaction is hydrogen gas evolution and formation of hydroxide.
  • chlorine reacts with water and hydroxide to form a hypochlorite-hypochlorous acid mixture that in turn results in formation of alkali metal chlorate and alkali metal chloride.
  • substantially no hexavalent chromium is added is meant less than about 30 molar%, for example less than about 20 molar% or less than about 10 molar% or less than about 3 molar%, for example less than about 1 molar% or less than about 0.1 molar% of hexavalent chromium is added based on the total amount of chromium added to the process from an external source. According to one embodiment, no hexavalent chromium is added to the process from an external source.
  • electrolyte solution is meant to include the volume of all streams or solutions circulated to the electrochemical cell(s) or that will be introduced into the cell electrolyte.
  • liquids include, but are not limited to, alkaline scrubber solutions, brine solutions, make-up streams, process water and condensate recycled solutions.
  • streams include solutions of chromium compounds which do not contain any alkali chloride and/or chlorate or are alkali chloride and/or chlorate depleted electrolyte solutions.
  • concentrations of anions e.g. chloride, chlorate, hypochlorite, chromate, dichromate, sulphate, perchlorate etc, are defined as equivalent contents of their respective anhydrous sodium salts, for example NaCI, NaCI0 3 , NaCIO, Na 2 Cr0 4 , Na 2 Cr 2 0 7 , Na 2 S0 4 and NaCI0 4 .
  • hypochlorite level stated corresponds to the hypochlorite level after transferring both Cl 2 and HCIO to hypochlorite in alkaline solution by the equilibrium reactions above.
  • the present invention facilitates the process of providing alkali metal chlorate by excluding or minimizing the addition of highly toxic hexavalent chromium which is usually added to the aqueous chloride electrolyte solution in the form of sodium dichromate dihydrate (Na 2 Cr 2 0 7 ⁇ 2H 2 0), potassium chromate (K 2 Cr0 4 ) or mixtures thereof from an external source.
  • highly toxic hexavalent chromium which is usually added to the aqueous chloride electrolyte solution in the form of sodium dichromate dihydrate (Na 2 Cr 2 0 7 ⁇ 2H 2 0), potassium chromate (K 2 Cr0 4 ) or mixtures thereof from an external source.
  • At least one chromium compound having a valence lower than +6 is added to at least one process stream containing either alkali metal chloride or alkali metal chlorate or to at least one process stream containing both alkali metal chlorate and alkali metal chlorate.
  • hexavalent chromium for example in the form of sodium dichromate, can, even if added in inconsiderable amounts, be added to the process from an external source, in an aqueous solution, either separately or in combination with a chromium compound with a valence lower than +6, for example a chromium(lll) compound.
  • chromium compounds by the wording "added to the process from an external source", as opposed to hexavalent chromium formed in the process, i.e. in-situ formation, is meant added to any process stream, for example an electrolyte stream or other process streams or to any tank, container, scrubber, reactor connected to the cell or directly to the cell.
  • “added to the process” includes any addition point to the process from which chromium with a valence lower than +6 can be added.
  • +6 is transferred from one cell line to another cell line with a compatible electrolyte composition although these may be disconnected during normal operation.
  • An example of transfer between compatible cell lines is the transfer of electrolyte from a unit for making potassium chlorate to a unit for making sodium chlorate.
  • formation of hexavalent chromium is made by addition of a chromium compound with a valence lower than +6 to for example a separate medium, for example in a separate vessel, from which medium transfer of chromium compounds takes place via a process stream to the process prior to, simultaneously or subsequently to formation of hexavalent chromium.
  • all or substantially all hexavalent chromium is formed in-situ.
  • the addition of chromium compounds having a valence lower than +6 may take place either during electrolysis or when the electrolysis is stopped. In particular it can take place when the starting electrolyte is prepared prior to the first start-up of a new production unit.
  • chromium compounds for example dissolved in an aqueous solution, having a valence lower than +6, for example trivalent chromium can be added in a separate vessel, optionally a temporarily disconnected vessel, for example a tank, and oxidized in such vessel to hexavalent chromium (in-situ generation thereof), for example by means of hypochlorite, chlorine, chlorite, chlorate, perchlorate, chlorine dioxide, hydrogen peroxide, sodium peroxide, sodium peroxysulfate, ozone, oxygen, air or other oxidizing agent or by electrochemical anodic oxidation.
  • Such chromium compounds can subsequently be transferred to the electrolytic cell via a process stream by pumping the chromium compound solution towards the cell.
  • hexavalent chromium is formed from at least one chromium compound having a valence lower than +6 by means of oxidation in an aqueous solution which hexavalent chromium is subsequently transferred to the electrolytic cell.
  • said at least one chromium compound with a valence lower than +6 is added in an amount resulting in a chromium content ranging from about 0.1 to about 20 g/l, for example from about 1 to about 10 or from about 2 to about 6 g (calculated as sodium dichromate equivalents)/! electrolyte solution.
  • chromium compound(s) with a valence lower than +6 is/are added in an amount of from about 0.1 to about 200, for example from about 0.1 to about 100, or from about 0.1 to about 80 or from about 1 to about 60 or from about 2 to about 20 g chromium/ton produced chlorate.
  • addition of at least one chromium compound having a valence lower than +6, for example chromium (III), to the process may be made to the alkaline scrubber liquid and/or to the cell line loop after the cells.
  • addition of at least one chromium compound having a valence lower than +6 may also be made to the electrolyte solution introduced into the cell which electrolyte solution is to be electrolyzed.
  • the chromium compound can also be added to the electrolyzed solution prior to the reactor; to the process stream from the mother liquor scrubber; and/or to the reactor gas scrubber.
  • the chromium compound may also be added upstream of an electrolyte filter to prevent product contamination with small amounts of possibly strongly colored insoluble chromium compounds, initially present in the chromium source or formed in the process.
  • chromium compounds having a valence lower than +6 may be for example chromium halides such as chromium(ll)chloride, chromium(lll)chloride, chromium(lll)chloride hexahydrate, chromium oxide such as chromium(ll)oxide (CrO), chromium(lll)oxide (Cr 2 0 3 ), chromic hydroxide, chromium(IV)oxide, chromic nitrate (Cr(N0 3 )2*9H 2 0), ammonium chromate, chromic hydroxyl dichloride (Cr(OH)CI 2 ), chromium sulfate pentadecahydrate, chromium sulfate, chromium hydroxide sulfate, chromium phosphate, chromite (FeCr 2 0 4 ), or any mixtures thereof.
  • chromium halides such as
  • the chromium compounds can for example be added as salts, aqueous solutions or as melts if the melting point is sufficiently low, for example chromium trichloride hexahydrate having a melting point of 83 °C.
  • Solid compounds containing leachable chromium can also be used as chromium source.
  • chromium compounds for use may be Cr(0), for example elemental chromium, Cr(l), Cr(ll), Cr(lll), Cr(IV), Cr(V) or any combinations thereof.
  • at least one Cr(lll) compound is used.
  • the extent of electrolysis is controlled to produce an effluent from the cell in which the desired weight ratio of alkali metal chlorate to alkali metal chloride usually ranges from (expressed as a weight ratio) about 1 :1 to about 20:1 , for example from about 1 :1 to about 15:1 or from about 2:1 to about 10:1 .
  • the electrolyte solution may be further processed to crystallize the alkali metal chlorate such as sodium chlorate for a variety of purposes, for example for the production of chlorine dioxide for use in the bleaching of chemical cellulosic pulps, by reduction in the presence of a strong mineral acid, usually sulphuric or hydrochloric acid.
  • Chlorine dioxide may also be generated directly from the electrolyte without prior isolation of the chlorate, typically by adding hydrochloric acid which acts both as an acid and a reducing agent.
  • the electrolysis produces a gaseous by-product, mainly consisting of hydrogen but also some oxygen, chlorine, hypochlorous acid, carbon dioxide and water vapour.
  • the by-product gas stream is passed through a water condenser scrubber wherein part of the stream is condensed to form an aqueous solution of hypochlorous acid, typically about 2 to 25 g/l HOCI, which aqueous solution also contains small amounts of dissolved chlorine, which can be recirculated to the cell.
  • the by-product gas effluent from the water gas scrubber is optionally passed through one or several alkaline scrubbers in which chlorine and hypochlorous acid are reactively absorbed to form hypochlorite.
  • alkaline scrubbers in which chlorine and hypochlorous acid are reactively absorbed to form hypochlorite.
  • a mother liquid scrubber using the alkaline effluent from the crystallizer.
  • a caustic scrubber using for example a NaOH solution.
  • the present invention is particularly directed to in- situ formation of hexavalent chromium for use in the electrolytic production of aqueous sodium chlorate from aqueous sodium chloride.
  • the present invention may also be used in the electrolytic production of any aqueous alkali metal chlorate solution by the electrolysis of the corresponding chloride in which the hexavalent chromium is useful.
  • Such aqueous alkali chlorate solutions include besides sodium chlorate also potassium chlorate, lithium chlorate, rubidium chlorate and cesium chlorate; alkaline earth metal chlorates, such as beryllium chlorate, magnesium chlorate, calcium chlorate, strontium chlorate, barium chlorate and radium chlorate, and mixtures of two or more such chlorates, which may also contain dissolved quantities of alkali metal chlorides, alkaline earth metal chlorides and mixtures thereof.
  • the electrolytic cell is a non-divided cell, e.g. a monopolar cell. This enables a variety of cell configurations. At least one electrode pair of anode and cathode may form a unit containing an electrolyte solution between the anode and cathode which unit may have the shape of plates or tubes. A plurality of electrode pairs may also be immersed in a cell box.
  • the cell is a bipolar cell. A similar variety of bipolar cell configurations are also possible.
  • the cell is a hybrid cell, i.e. a combined monopolar and bipolar cell.
  • This type of cells enables upgrading of monopolar technology by combining monopolar and bipolar sections in a cell-box. Such combination may be set up by arranging e.g. two or three electrodes herein as a bipolar section among a plurality of monopolar electrodes.
  • the monopolar electrodes of the hybrid cell may be of any type including e.g. conventional electrodes known per se.
  • separate monopolar anodes and cathodes are mounted in an electrolytic cell at the ends, whereas bipolar electrodes are mounted in between thereby forming a hybrid electrolytic cell.
  • the current density of the electrolytic process ranges from about 0.6 to about 4.5, for example from about 1 to about 3, or from about 1 .3 to about 2.9 kA/m 2 .
  • the pH is adjusted at several positions within the range from about 4 to about 12 to optimize the process conditions for the respective unit operation.
  • a weakly acidic or neutral pH is used in the electrolyzer and in the reaction vessels to promote the reaction from hypochlorite to chlorate, while the pH in the crystallizer is alkaline to prevent gaseous hypochlorite and chlorine from being formed and released to reduce the risk of corrosion.
  • the pH of the cell electrolyte solution i.e. the solution comprising alkali metal chloride undergoing electrolysis in the electrochemical cell ranges from about 4 to about 7.5, for example, from about 4 to about 6.5 or from about 4 to 6 or from about 4 to 5.75 or from about 4 to 5.5.
  • the pH of the cell electrolyte solution ranges from about 5.0 to about 7.5, such as from about 6.5 to about 7.0.
  • the pH at the point of addition of a chromium compound having a valence lower than +6 also may range from about 4 to about 7.5, for example from about 4 to about 6.5 or from about 4 to 6 or from about 4 to 5.75 or from about 4 to 5.5.
  • the pH of the cell electrolyte solution ranges from about 5.0 to about 7.5, such as from about 6.5 to about 7.0.
  • the concentration of chlorate and of chloride as well as hypochlorite in the electrolyte used in the electrochemical cell may vary widely, depending on the extent of electrolysis of the chloride solution.
  • the electrolyte solution contains alkali metal halide, e.g. sodium chloride in a concentration from about 80 to about 180, for example from about 100 to about 140 or from about 106 to about 125 g/l electrolyte.
  • the electrolyte solution contains alkali metal chlorate in a concentration from about 200 to about 700, e.g. from about 450 to about 650 or from about 550 to about 610 g/l.
  • the concentration of hypochlorite in the electrolyte solution ranges from about 0 to about 6, for example from about 0.01 to about 4 or from about 0.1 to about 4 or from about 0.3 to about 3 g/l.
  • the electrolyte may also comprise significant amounts of inactive compounds accumulated in the process over the course of time, for example sodium sulfate introduced as an impurity in the sodium chloride source or sodium perchlorate formed by a side reaction in the process.
  • the weight ratio of chromium derived from chromium compound(s) having a valence lower than +6 added to the process to hypochlorite ranges from about 1 :30 to about 3:1 , for example from about 1 :10 to about 2:1 , or from about 1 :8 to about 1 :1 .
  • the amount of hexavalent chromium formed from the chromium compound having a valence lower than +6 is in the range from about 0.1 to about 25 grams calculated as sodium dichromate ions/I electrolyte solution in the cells, for example from about 0.2 to about 15 g/l electrolyte solution, for example from about 1 to about 8 g/l electrolyte solution.
  • a corresponding amount of chromium compound with a valence lower than +6 is added.
  • the flow to the chlorate cells normally is from 75 to 200 m 3 of electrolyte per metric ton of alkali metal chlorate produced.
  • the electrolytic cell operates at a temperature ranging from about 60 to about 100 °C, or from about 65 to about 90 °C.
  • the temperature of the stream or solution at the addition point of a chromium compound having a valence lower than +6 ranges from about 60 to about 100 °C, or from about 65 to about 90 °C.
  • the temperature of the stream or solution at the addition point of a chromium compound having a valence lower than +6 ranges from about 15 to about 40 °C, for example from about 15 to 30 °C.
  • a part of the electrolyzed solution is recycled from the reaction vessels to a salt dissolver, and a part is recycled for alkalization and electrolyte filtration and final pH adjustment before introduction into the chlorate crystallizer. Water from the thus alkalized electrolyte can be evaporated in the crystallizer.
  • the mother liquor which is saturated with respect to chlorate and contains high contents of sodium chloride, is recycled directly to the preparation slurry via cell gas scrubbers and reactor gas scrubbers.
  • the pressure in the cell is about 20 to 30 mbar above the atmospheric pressure.
  • the (electrical) conductivity in the cell electrolyte ranges from about 200 to about 700, for example from about 300 to about 600 mS/cm.
  • the electrolytic cell and the electrodes arranged therein may be as further disclosed in EP 1242654 and WO 2009/063031 .
  • the invention also relates to the use of an aqueous solution or a melt of chromium compounds as an additive to a chlorate process, said solution comprising at least one hexavalent chromium compound and at least one chromium compound having a valence lower than +6, wherein the molar ratio of hexavalent chromium to chromium having a valence lower than +6 ranges from about 1 :10000 to about 3:10, for example from about 1 :10000 to about 2:10, for example from about 1 :10000 to about 1 :10, for example from about 1 :10000 to about 1 :100 or from about 1 :10000 to about 1 :1000, or from about 0:10000 to about 1 :10000.
  • the molar ratio of hexavalent chromium to chromium having a valence lower than +6 ranges from about 0:10000 to about 1 :10000.
  • Chromium free chlorate electrolyte (1 10 g/l NaCI, 550 g/l NaCI0 3 in water, no pH adjustment).
  • 1 .5 dm 3 electrolyte containing 120 g/l NaCI and 580 g/l NaCI0 3 was prepared by dissolution at 90 °C in water and dilution to 1 .5 dm 3 .
  • Chlorate electrolyte was withdrawn from the electrolysis cell outlet of a chlorate plant during operation.
  • the addition of a small amount of CrCI 3 * 6H 2 0 crystals resulted in complete dissolution and oxidation of chromium (III) to chromium (VI).
  • a larger amount of CrCI 3 * 6H 2 0 resulted in formation of a brown precipitation whereby no further oxidation to hexavalent chromium took place.
  • a hypochlorite containing caustic scrubber solution was withdrawn from a chlorate plant and CrCI 3 * 6H 2 0 crystals were added (-0.1 g/100ml electrolyte).
  • the CrCI 3 * 6H 2 0 crystals first dissolved forming a green solution and later oxidized forming a pale yellow Cr(VI) containing solution.
  • Sodium hypochlorite can oxidize chromium(lll) to chromium(VI) in strongly alkaline solutions and down to at least pH 5.8, for example to at least pH 5 or below pH 5. Hypochlorite can even dissolve precipitations formed in neutral solutions and oxidize chromium with a valence lower than +6 to hexavalent state.
  • These examples demonstrate that trivalent chromium but also other valencies of chromium lower than +6 are a viable alternative to hexavalent chromium as raw material in a process for the production of alkali metal chlorate since it is easily oxidized to the hexavalent state; either by chlorate or hypochlorite oxidation.
  • Addition of a chromium compound, for example chromium(lll) to the process may be made for example in the scrubber caustic solution, in the cell line loop after the cells, or to the inlet of the cell.
  • a 203 ml (conventional dichromate-containing) electrolyte composition containing 1 10 g/dm 3 NaCI, 550 g/dm 3 NaCI0 3 , 5.0 g/dm 3 Na 2 Cr 2 0 7 was used in trials conducted at a pH of 6.1 and a temperature of 25 °C.
  • a hypochlorite solution of 2 g (NaCIO content was 124 g/dm 3 ) was added to the electrolyte and subsequently 0.4788 g of a 50 wt% solution of Cr(lll)CI 3 x 6H 2 0..

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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)

Abstract

L'invention porte sur un procédé pour la production de chlorate de métal alcalin dans une cellule électrolytique comprenant une anode et une cathode, au moins un composé du chrome ayant une valence inférieure à +6 étant ajouté au procédé, ledit ou lesdits composés du chrome étant oxydés en chrome hexavalent dans ledit procédé, pratiquement pas de chrome hexavalent étant ajouté au procédé à partir d'une source externe. L'invention porte également sur l'utilisation d'une solution aqueuse de composés du chrome comme additif pour un procédé de production de chlorate.
PCT/EP2011/073167 2010-12-22 2011-12-19 Procédé électrolytique WO2012084765A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BR112013015155-2A BR112013015155A2 (pt) 2010-12-22 2011-12-19 processo de produção de um clorato de metal alcalino em uma célula eletrolítica e uso de uma solução aquosa de compostos de cromo como um aditivo a um processo de clorato
EA201390875A EA025314B1 (ru) 2010-12-22 2011-12-19 Электролитический способ получения хлората щелочного металла
US13/996,686 US20130292261A1 (en) 2010-12-22 2011-12-19 Electrolytic Process
CA2821309A CA2821309A1 (fr) 2010-12-22 2011-12-19 Procede electrolytique
EP11802908.1A EP2655692A1 (fr) 2010-12-22 2011-12-19 Procédé électrolytique

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201061425927P 2010-12-22 2010-12-22
EP10196408 2010-12-22
US61/425,927 2010-12-22
EP10196408.8 2010-12-22

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WO2012084765A1 true WO2012084765A1 (fr) 2012-06-28

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EP (1) EP2655692A1 (fr)
CA (1) CA2821309A1 (fr)
EA (1) EA025314B1 (fr)
WO (1) WO2012084765A1 (fr)

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CN108103521B (zh) * 2017-12-22 2019-10-15 四川省银河化学股份有限公司 一种提高电解法制备铬酸酐品质的方法
CN110129820B (zh) * 2019-06-25 2021-01-05 山东瑞克环境科技有限公司 次氯酸钙、氯酸钙、高氯酸钙制备装置及方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0266128A2 (fr) 1986-10-29 1988-05-04 Tenneco Canada Inc. Production de chrome hexavalant à utiliser dans des cellules de production électrolytique de chlorate
EP1242654A1 (fr) 1999-12-28 2002-09-25 Akzo Nobel N.V. Procede et systeme de ventilation de gaz hydrogene
WO2009063031A2 (fr) 2007-11-16 2009-05-22 Akzo Nobel N.V. Électrode

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5294307A (en) * 1992-07-31 1994-03-15 Huron Tech Corp Integrated process for the production of alkali and alkaline earth metal chlorates and chlorine dioxide

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0266128A2 (fr) 1986-10-29 1988-05-04 Tenneco Canada Inc. Production de chrome hexavalant à utiliser dans des cellules de production électrolytique de chlorate
EP1242654A1 (fr) 1999-12-28 2002-09-25 Akzo Nobel N.V. Procede et systeme de ventilation de gaz hydrogene
WO2009063031A2 (fr) 2007-11-16 2009-05-22 Akzo Nobel N.V. Électrode

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
KIRK-OTHMER: "Encyclopedia of Chemical Technology", vol. 6, 2001, JOHN WILEY & SONS, INC., pages: 526 - 570
See also references of EP2655692A1

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EP2655692A1 (fr) 2013-10-30
US20130292261A1 (en) 2013-11-07
EA025314B1 (ru) 2016-12-30
CA2821309A1 (fr) 2012-06-28
EA201390875A1 (ru) 2013-09-30

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