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WO1996034997A1 - Element electrochimique et procede de separation d'une solution de sulfate et de production d'une solution d'hydroxyde, de l'acide sulfurique et un halogene gazeux - Google Patents

Element electrochimique et procede de separation d'une solution de sulfate et de production d'une solution d'hydroxyde, de l'acide sulfurique et un halogene gazeux Download PDF

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Publication number
WO1996034997A1
WO1996034997A1 PCT/US1995/016123 US9516123W WO9634997A1 WO 1996034997 A1 WO1996034997 A1 WO 1996034997A1 US 9516123 W US9516123 W US 9516123W WO 9634997 A1 WO9634997 A1 WO 9634997A1
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Prior art keywords
solution
ions
sulfate
membrane
cell
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PCT/US1995/016123
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English (en)
Inventor
Kenneth Bernard Keating
James Arthur Trainham, Iii
Clarence Garlan Law, Jr.
John Scott Newman
Douglas John Eames
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E.I. Du Pont De Nemours And Company
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Priority to AU44213/96A priority Critical patent/AU4421396A/en
Publication of WO1996034997A1 publication Critical patent/WO1996034997A1/fr

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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • 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
    • C25B1/16—Hydroxides
    • 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
    • C25B1/22—Inorganic acids
    • 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
    • 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
    • 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
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
    • 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
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/60—Constructional parts of cells
    • C25B9/65—Means for supplying current; Electrode connections; Electric inter-cell connections
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/2465—Details of groupings of fuel cells
    • H01M8/247—Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H01M8/0208—Alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0228—Composites in the form of layered or coated products
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to an electro ⁇ chemical cell and a process for splitting a solution and producing a hydroxide, sulfuric acid and a halogen gas.
  • the cell and the process may convert either an anhydrous or an aqueous hydrogen halide, such as hydrogen chloride, to a halogen gas, such as chlorine gas, and a. solution such as a sodium sulfate aqueous solution, to form sulfuric acid and sodium hydroxide, along with its co-product, hydrogen.
  • Hydrogen chloride (HC1) or hydrochloric acid is a reaction by-product of many manufacturing processes which use chlorine.
  • chlorine is used to manufacture polyvinyl chloride, isocyanates, and chlorinated hydrocarbons/fluorinated hydrocarbons, with hydrogen chloride as a by-product of these processes.
  • supply so exceeds demand hydrogen chloride or the acid produced often cannot be sold or used, even after careful purification. Shipment over long distances is not economically feasible. Discharge of the acid or chloride ions into waste water streams is environmentally unsound. Recovery and feedback of the chlorine to the manufacturing process is the most desirable route for handling the HC1 by-product.
  • a number of commercial processes have been developed to convert HC1 into usable chlorine gas. See, e.g., F. R. Minz, "HCl-Electrolysis - Technology for Recycling Chlorine", Bayer AG, Conference on Electrochemical Processing, Innovation & Progress, Glasgow, Scotland, UK, 4/21-4/23, .1993.
  • the current electrochemical commercial process is known as the Uhde process.
  • aqueous HCl solution of approximately 22% is fed at 65° to 80° C to both compartments of an electrochemical cell, where exposure to a direct current in the cell results in an electro ⁇ chemical reaction and a decrease in HCl concentration to 17% with the production of chlorine gas and hydrogen gas.
  • a polymeric separator divides the two compartments.
  • the process requires recycling of dilute (17%) HCl solution produced during the electrolysis step and regenerating an HCl solution of 22% for feed to the electrochemical cell.
  • the overall reaction of the Uhde process is expressed by the equation:
  • the chlorine gas produced by the Cttide process is wet, usually containing about 1% to 2% water. This wet chlorine gas must then be further processed to produce a dry, usable gas. If the concentration of HCl in the water becomes too low, it is possible for oxygen to be generated from the water present in the Uhde process. This possible side reaction of the Uhde process due to the presence of water, is expressed by the equation:
  • the presence of water in the Uhde system limits the current densities at which the cells can perform to less than 500 amps./ft. 2 , because of this side reaction.
  • the side reaction results in reduced electrical efficiency and corrosion of the cell components.
  • Balko employs an electrolytic cell having a solid polymer electrolyte membrane. Hydrogen chloride, in the form of hydrogen ions and chloride ions in aqueous solution, is introduced into an electrolytic cell. The solid polymer electrolyte membrane is bonded to the anode to permit transport from the anode surface into the membrane. In Balko, controlling and minimizing the oxygen evolution side reaction is an important consideration. Evolution of oxygen decreases cell efficiency and leads to rapid corrosion of components of the cell. The design and configuration of the anode pore size and electrode thickness employed by Balko maximizes transport of the chloride ions.
  • Electrodialysis a technology based on the use of cation-exchange and/or anion exchange membranes and of an electric field to effect ion separations, has been the subject of many recent books, articles and papers. See, for example, "Membrane Handbook", edited by .S.W. Ho and K.K. Sirkar, Van Nostrand Reinhold, New York; "The Green Potential of Electrochemistry, Part 2 Application” by D. Pletcher and N.L. Weinberg, Chemical Engineering. November, 1992, pg. 132 - 141. In recent years, DeNora Permelec, spA, of Milan, Italy, has developed the HYDRINA ® process, which generates sodium hydroxide without producing chlorine, using principles of electrodialysis.
  • Fig. 1 herein shows a schematic of a three-component cell, shown generally at 1, for splitting sodium sulfate.into sulfuric acid and sodium hydroxide.
  • cell 1 includes an anode 2, an anion-exchange membrane membrane 4, a cation exchange membrane 6 and a cathode 8.
  • An aqueous solution of sodium sulfate is introduced into a central compartment bounded by anion exchange membrane 4, facing anode 2.
  • anion exchange membrane 4 facing anode 2.
  • sulfate ions migrate toward the anode and pass through the anion exchange membrane, where they combine with protons produced from water.
  • the water is introduced into the anode compartment, where, by means of an electrochemical reaction, it is converted into protons and oxygen.
  • Sodium ions from the sodium sulfate migrate through cation-exchange membrane 6 to the cathode compartment, which is also fed with water or dilute sodium hydroxide, whereby they combine with hydroxyl ions formed by the electro ⁇ chemical reaction of the reduction of water to hydrogen and hydroxyl ion.
  • the products of the electrodialysis are sulfuric acid and sodium hydroxide, and the gases, oxygen and hydrogen.
  • ion-selective membranes that is, membranes which permit only cations (cation exchange membranes) or anions (anion exchange membranes) to pass therethrough, and reject ions of opposite charge.
  • a number of such membranes are now commercially available, such as a membrane which is made of hydrated, copolymers of polytetrafluoroethylene and poly-sulfonyl fluoride vinyl ether-containing pendant sulfonic acid groups, and sold under the trademark "NAFION” (hereinafter referred to as NAFION ® ) by E. I. du Pont de Nemours and Company of Wilmington, Delaware (hereinafter referred to as "DuPont”) .
  • the present invention solves the problems of the prior art by providing a single process and apparatus for recycling a hydrogen halide and sulfate solution into useful products. More specifically, the present invention solves the problems of the prior art by providing a process and an electrochemical cell which permit simultaneous production of three useful materials, fundamental to the modern chemical industry, halogen gas, such as chlorine, an acid, such as sulfuric acid, and a base, such as sodium hydroxide, from two materials, very often formed as a by-product of chemical processes, and under environmental restraint and facing large excesses in the market place, such as hydrogen chloride and sodium sulfate.
  • halogen gas such as chlorine
  • an acid such as sulfuric acid
  • a base such as sodium hydroxide
  • Such process and cell are especially useful at a plant site where both hydrogen chloride and sodium sulfate are produced, and where the products of such a process and cell could be recycled to other production processes.
  • the electrochemical cell and the process of the present invention use an essentially anhydrous hydrogen halide as a reactant.
  • This process allows for direct processing of anhydrous hydrogen halide which is a by-product of manufacturing processes, without first dissolving the hydrogen halide in water.
  • This direct production of essentially dry halogen gas when done, for example, for chlorine gas, is less capital intensive than processes of the prior art, which require separation of water from the chlorine gas.
  • This direct production of essentially dry halogen gas also requires lower investment costs than the electrochemical conversions of hydrogen chloride of the prior art. This advantage can translate directly into lower power costs per pound of say, chlorine, generated than in the aqueous electro ⁇ chemical processes of the prior art.
  • the direct production of essentially dry halogen gas also provides a process which produces drier chlorine gas with fewer processing steps as compared to that produced by electrochemical or catalytic systems of the prior art, thereby simplifying processing conditions and reducing capital costs.
  • a process for producing a solution of hydroxide, sulfuric acid and a halogen gas from a hydrogen halide and a sulfate solution wherein hydrogen halide is fed to a first compartment of an electrochemical cell and is transported to an anode of the cell; a sulfate solution is fed to a second compartment of the cell, wherein the sulfate solution comprises s ⁇ ulfate ions and another ion; the hydrogen halide is oxidized at the anode to produce halogen gas and protons, and the protons are transported through a first cation-transporting membrane; the first membrane rejects the sulfate, ions and the sulfate ions join the protons to form a sulfuric acid solution; water is fed to a third compartment of the cell and is reduced to hydrogen and hydroxyl ion; and a second membrane
  • an electrochemical cell for producing a hydroxide solution, sulfuric acid and a halogen gas from a hydrogen halide and a sulfate solution, comprising means for introducing a sulfate solution, wherein the sulfate solution comprises sulfate ions and another type of ion; means for introducing hydrogen halide to a second compartment; means for oxidizing the hydrogen halide to produce halogen gas and protons; first cation-transporting means for transporting the protons therethrough, wherein the first cation- transporting means is disposed in contact with the oxidizing means and the first cation-transporting means rejects the sulfate ions and the sulfate ions join the protons to form a sulfuric acid solution; means for introducing water to a third compartment; means for reducing the water to hydrogen and hydroxyl ion; and second cation-transporting means for transporting the other ions therethrough, wherein
  • Fig. 1 is a schematic view of a three-compartment electrodialysis cell of the prior art for splitting sodium sulfate into sulfuric acid and sodium hydroxide.
  • Fig. 2 is an exploded, cross-sectional view of an electrochemical cell which produces an alkali metal hydroxide, sulfuric acid and a halogen by splitting an alkali metal solution according to the present invention.
  • Fig. 3A is a is a top cross-sectional view of the anode mass flow field as shown in Fig. 2.
  • Fig. 3B is a is a top cross-sectional view of the cathode mass flow field as shown in Fig. 2.
  • an electrochemical cell for producing a hydroxide solution, sulfuric acid and a halogen gas from a hydrogen halide and a solution.
  • a cell is shown generally at 10 in Fig. 2.
  • hydrogen as well as chlorine gas, is produced.
  • the cell of the present invention may use anhydrous hydrogen chloride as a reactant and directly produce essentially dry chlorine gas, which will be referred to as the anhydrous case.
  • directly means that the electrochemical cell obviates the need to remove water from the halogen gas produced or the need to convert essentially anhydrous hydrogen halide to aqueous hydrogen halide before electrochemical treatment.
  • the cell of the present invention may also use aqueous hydrogen chloride as a reactant and produce wet chlorine, which will be referred to as the aqueous case.
  • the cell of the present invention will be described as using hydrogen chloride as a reactant to produce chlorine gas, in either the anhydrous or the aqueous case.
  • this cell may alternatively be used to produce other halogen gases, such as bromine, fluorine (in the anhydrous case only) and iodine from a respective anhydrous hydrogen halide, such as hydrogen bromide, hydrogen fluoride and hydrogen iodide.
  • the cell is described and shown for splitting a sodium sulfate solution,
  • the electrochemical cell of the present invention comprises means for introducing a sulfate solution to a first compartment.
  • the inlet means preferably comprises an inlet 22 as shown in Fig. 2.
  • a sulfate solution which is sodium sulfate NaS0 4 (aq) in Fig. 2, is introduced through inlet 22.
  • the sulfate solution comprises sulfate ions and another type of ion.
  • the other type of ion may be either an alkali metal ion, an alkaline earth metal ion or an ammonium ion.
  • the present invention need not be limited to these ions, provided that the ions are capable of being transmitted through a cation-transporting membrane.
  • the hydroxide solution is an alkali metal solution
  • the sulfate solution is an alkali metal sulfate solution.
  • the alkali metal is either sodium or potassium.
  • the hydroxide solution is an alkaline earth metal hydroxide solution
  • the sulfate solution is an alkaline earth metal sulfate solution.
  • Examples of the alkaline earth metals particularly useful with the present invention include calcium and magnesium.
  • the other type of ion is an ammonium ion
  • the hydroxide solution is an ammonium solution
  • the sulfate solution is an ammonium sulfate solution.
  • the electrochemical cell of the present invention also comprises means for introducing hydrogen halide to a second compartment.
  • the means for introducing hydrogen halide is an inlet 14 as shown in Fig. 2.
  • electrochemical cell 10 has an anode-side outlet 16 as shown in Fig. 2. Since in the preferred embodiment, anhydrous HCl is carried through the inlet, and chlorine gas is carried through the outlet, the inlet and the outlet may be lined with a fluoropolymer, sold under the trademark TEFLON ® PFA by DuPont.
  • the electrochemical cell of the present invention also comprises means for oxidizing hydrogen halide to produce halogen gas and protons.
  • the oxidizing means comprises means for oxidizing molecules of essentially anhydrous hydrogen halide, preferably anhydrous hydrogen chloride, to produce essentially dry halogen gas, preferably, chlorine gas.
  • the oxidizing means comprises means for oxidizing ions of aqueous hydrogen halide, preferably hydrogen chloride, to produce wet halogen gas, preferably chlorine gas.
  • the oxidizing means comprises an anode 12 as shown in Fig.
  • membrane 18 may be a proton- conducting membrane.
  • Membrane 18 may be a commercial cationic membrane made of a fluoro- or perfluoro- polymer, preferably a copolymer of two or more fluoro or perfluoromonomers, at least one of which has pendant sulfonic acid groups. The presence of carboxylic groups is not desirable, because those groups tend to decrease the conductivity of the membrane when they are protonated.
  • Suitable resin materials are available commercially or can be made according to patent literature. They include fluorinated polymers with side chains of the type -CF 2 CFRS0 3 H and
  • Suitable cationic membranes which are made of hydrated, ' copolymers of polytetrafluoroethylene and poly-sulfonyl fluoride vinyl ether-containing pendant sulfonic acid groups, are offered by DuPont under the trademark "NAFION” (hereinafter referred to as NAFION ® ) .
  • NAFION ® membranes containing pendant sulfonic acid groups include NAFION ® 117,
  • NAFION ® 324 and NAFION ® 417 are both supported and has an equivalent weight of 1100 g., equivalent weight being defined as the amount of resin required to neutralize one liter of a 1M sodium hydroxide solution. w
  • the other two types of NAFION ® are both supported on a fluorocarbon fabric, the equivalent weight of NAFION ® 417 also being 1100 g.
  • NAFION ® 324 has a two-layer structure, a 125 ⁇ -thick membrane having an equivalent weight of 1100 g., and a 25 ⁇ m-thick membrane having an equivalent weight of 1500 g.
  • the sulfate solution comprises sulfate ions and another type of ion.
  • the sulfate ions join the protons which are transported through membrane 18 to form a sulfuric acid solution, H 2 S0 4 a mecanic ) as shown in Fig. 2.
  • the electrochemical cell of the present invention also comprises means for introducing water to a third compartment.
  • the means for introducing water comprises an inlet 24. Water, H 2 0 as shown in Fig. 2, enters the cell through inlet 24.
  • the electrochemical cell of the present invention also comprises means for reducing the water to produce hydroxyl ions and hydrogen.
  • the reducing means comprises a cathode 20.
  • the cathode reduces the water to hydrogen and hydroxyl ion.
  • the hydrogen (H 2 ) leaves the cell through an outlet 26 as shown in Fig. 2.
  • the electrochemically active material may comprise any type of catalytic or metallic material or metallic oxide, as long as the material can support charge transfer.
  • the electro- chemically active material may comprise a catalyst material such as platinum, ruthenium, osmium, rhenium, rhodium, iridium, palladium, gold, titanium or zirconium and the oxides, alloys or mixtures thereof.
  • the oxides of these materials are not used for the cathode.
  • Other catalyst materials suitable for use with the present invention may include, but are not limited to, transition metal macro cycles in monomeric and polymeric forms and transition metal oxides, including perovskites and pyrochores.
  • the electrochemically active material may comprise a catalyst material on a support material.
  • the support material may comprise particles of carbon and particles of polytetrafluoro ⁇ ethylene, which is sold under the trademark "TEFLON” (hereinafter referred to as TEFLON ® ) , commercially available from DuPont.
  • the electrochemically active material may be bonded by virtue of the TEFLON ® to a support structure of carbon paper or graphite cloth and hot-pressed to the cation-transporting membrane.
  • the hydrophobic nature of TEFLON ® does not allow a film of water to form at the anode. A water barrier in the electrode would hamper the diffusion of HCl to the reaction sites.
  • the electrodes are preferably hot- pressed into the membrane in order to have good contact between the catalyst and the membrane.
  • the loadings of electrochemically active material may vary based on the method of application to the membrane.
  • Hot-pressed, gas-diffusion electrodes typically have loadings of 0.10 to 0.50 mg/cm 2 .
  • Lower loadings are possible with other available methods of deposition, such as distributing them as thin films from inks onto the membranes, as described in Wilson and Gottesfeld, "High Performance Catalyzed Membranes of Ultra-low Pt Loadings for Polymer Electrolyte Fuel Cells", Los Alamos National Laboratory, J. Electrochem. Soc, Vol. 139, No.
  • the electrochemical cell of the present invention also comprises second cation-transporting means for transporting the other type of ion therethrough, wherein the second cation-transporting means is disposed in contact with the reducing means.
  • the second cation-transporting means preferably comprises a second cation-transporting membrane 19 as shown in Fig. 2. As shown in Fig.
  • first cation-transporting membrane 18 and second cation-transporting membrane 19 face each other.
  • the second cation-transporting membrane may be made of any of the materials or constructed like any of the configurations as described above for the first cation-transporting membrane.
  • each membrane 20/membrane 19 are similar to membrane electrode assemblies (MEA's) of the prior art, except that in the present invention, each membrane is disposed in contact with only one electrode, rather than two. Both the first and the second membranes are hydrated by the water present in the feed of the aqueous sodium sulfate.
  • the second cation-transporting means, or membrane rejects the hydroxyl ions, as illustrated by the angled arrow off membrane 19, and the hydroxyl ions are joined with the other type of ions to form a solution of hydroxide, such as sodium hydroxide NaOH(aq) as shown in Fig. 2, which exits the cell through outlet 26.
  • the electrochemical cell of the first and second embodiments further comprises an anode flow field 28 disposed in contact with the anode and a cathode flow field 30 disposed in contact with the cathode.
  • the flow fields are electrically conductive, and act as both mass and current flow fields.
  • the purpose of the anode flow field is to get reactants, such as anhydrous HCl in the first and second embodiments, to the anode and products, such as essentially dry chlorine gas from the anode.
  • the purpose of the cathode flow field is to get reactants, such as liquid water to the cathode and products, such as hydrogen gas, from the cathode.
  • anode mass flow field 28 includes a plurality of flow channels 29 as shown in Fig.
  • Fig. 3A for directing the anhydrous or aqueous HCl to the anode and chlorine gas away from the anode
  • the cathode mass flow field 30 includes a plurality of flow channels 31 as shown in Fig. 3B for directing the water added through cathode-side inlet 24 in Fig. 2 to the cathode and sodium hydroxide and hydrogen away from the cathode.
  • Fig. 3A is a cut-away, top cross-sectional view of the anode mass flow field of Fig. 1
  • Fig. 3B is a cut-away top cross-sectional view of the cathode mass flow field of Fig. 1.
  • the flow fields and the flow channels may have a variety -of configurations and may. be made of different materials. Also, the flow fields may be made in any manner known to one skilled in the art.
  • the electrochemical cell of the present invention may also comprise an anode mass flow manifold 32 and a cathode mass flow field manifold 34 as shown in Fig. 2.
  • the purpose of such manifolds is to form a frame around the anode mass flow field and the anode, and the cathode mass flow field and the cathode, respectively.
  • These manifolds are preferably made of a corrosion resistant material, such as TEFLON ® PFA.
  • a gasket 36, 38 also contributes to forming a frame around the respective anode and cathode mass flow fields.
  • These gaskets are preferably also made of a corrosion resistant material, such as polytetrafluoroethylene, sold under the trademark TEFLON ® PTFE by DuPont.
  • the electrochemical cell of the first and second embodiments also comprises an anode current bus 46 and a cathode current bus 48 as shown in Fig. 2.
  • the current buses conduct current to and from a voltage source (not shown) .
  • anode current bus 46 is connected to the positive terminal of a voltage source
  • cathode current bus 48 is connected to the negative terminal of the voltage source, so that when voltage is supplied to the cell, current flows through all of the cell components to the right of current bus 46 as shown in Fig. 2, including current bus 48, from which it returns to the voltage source.
  • the current buses are made of a conductor material, such as copper.
  • the electrochemical cell of the present invention further comprises a current distributor disposed on one side of the flow field.
  • An anode current distributor 40 is shown in Fig. 2 disposed on one side of anode flow field 28, and a cathode current distributor 42 is shown in Fig. 2 disposed on one side of cathode flow field 30.
  • the anode current distributor collects current from the anode bus and distributes it to the anode by electronic conduction.
  • the cathode current distributor collects current from the cathode and distributes it to the cathode bus by electronic conduction.
  • the anode and the cathode current distributors preferably each comprise a non-porous layer.
  • the anode current distributor thus provides a barrier between the anode current bus and the hydrogen halide, such as hydrogen chloride and the halogen gas, such as chlorine.
  • the cathode current distributor provides a barrier between the cathode current bus and the liquid water added to the cathode inlet and hydrogen gas (H 2 (g) ) and the sodium hydroxide solution, NaOH(aq) exiting outlet 24.
  • the current distributors of the present invention may be made of a variety of materials, and the material used for the anode current distributor need not be the same as the material used for the cathode current distributor.
  • the anode current distributor is made of platinized tantalum
  • the cathode current distributor is made of a nickel-base alloy, such as UNS10665, sold as HASTELLOY ® B-2, by Haynes, International.
  • the electrochemical cell also comprises a conductive structural support 44 disposed in contact with anode current distributor 40.
  • the support on the anode side is preferably made of UNS31603 (316L stainless steel) .
  • a seal 45 preferably in the form of an O-ring made from a perfluoroelastomer, sold under the trademark KALREZ ® by DuPont, is disposed between structural support 44 on the anode side and anode current distributor 40.
  • anode current bus 46 in Fig. 2
  • structural support 44 is shown in front of anode current bus 46 in Fig. 2, it is within the scope of the present invention for the structural support to be placed behind the anode current bus (i.e., to the left of bus 46 as shown in Fig. 2) and still achieve the same results.
  • the cathode current distributor acts as a corrosion-resistant structural backer on the cathode side. This piece can be drilled and tapped to accept the TEFLON ® PFA fitting, which is used for the inlet and outlet.
  • the sulfate solution comprises sulfate ions and another type of ion.
  • the other type of ion may be either an alkali metal ion, an alkaline earth metal ion or an ammonium ion.
  • the present invention need not be limited to these ions, provided that the ions are capable of passing through the cation-exchange membrane.
  • the hydroxide solution is an alkali metal solution
  • the sulfate solution is an alkali metal sulfate solution.
  • the alkali metal is either sodium or potassium.
  • the hydroxide solution is an alkaline earth metal solution
  • the sulfate solution is an alkaline earth metal sulfate solution.
  • alkaline earth metals suitable for use with the process of the present invention are magnesium and calcium.
  • the other type of ion is an ammonium ion
  • the hydroxide solution is an ammonium solution
  • the sulfate solution is an ammonium sulfate solution.
  • hydrogen halide is fed to a first compartment of an electrochemical cell, such as cell 10, through an inlet, such as inlet 14 as shown in Fig. 2.
  • the hydrogen halide is transported to an anode, such as anode 12 as shown in Fig. 2.
  • anode current distributor 40 collects current fromthe anode bus and distributes it to the anode by electronic conduction.
  • the hydrogen halide is transported to an anode, such as anode 12 as shown in Fig. 2.
  • molecules of essentially anhydrous hydrogen halide are transported to the anode.
  • the hydrogen halide is oxidized at the anode to produce halogen gas, which is shown as Cl and which exits the cell through anode-side outlet 16 and protons, shown as H + as shown in Fig. 2.
  • ions of aqueous hydrogen halide are fed to the first compartment through inlet 14 and are oxidized at the anode.
  • the equation for the anode reaction in the aqueous case is: Electrical . Energy 2H+ + 2C1 ⁇ »-Cl 2 + 2H + + 2e ⁇
  • a sulfate solution which comprises sulfate ions and another type of ions, is fed through an inlet, such as inlet 22, to a second compartment of the cell.
  • the second compartment is disposed between a first cation- transporting membrane, such as membrane 18, and a second cation-transporting membrane 19, and the second cation-transporting membrane is disposed in contact with a cathode, such as cathode 20 as shown in Fig. 2.
  • the protons produced by the oxidation of hydrogen halide at the anode are transported through the first cation-transporting membrane, which is disposed in contact with anode 12 as shown in Fig. 2.
  • the first membrane rejects the sulfate ions, shown as S0 4 TM in Fig.
  • the second membrane rejects the hydroxyl ions as illustrated by the OH" and the angled arrow extending off membrane 19.
  • the hydroxyl ions are joined with the other type of ions, which in the illustrated case are sodium ions, to form a solution of alkali metal hydroxide, shown as NaOH(aq) in Fig. 2.
  • Cathode current distributor 42 collects current from cathode 20 and distributes it to cathode bus 48.
  • the electrochemical cell of the present invention can be operated over a wide range of temperatures.
  • Room temperature operation is an advantage, due to the ease of use of the cell.
  • operation at elevated temperatures provides the advantages of improved kinetics and increased electrolyte conductivity. Higher temperatures result in lower cell voltages.
  • limits on temperature occur because of the properties of the materials used for elements of the cell.
  • the properties of a NAFION ® membrane change when the cell is operated above 120° C.
  • the properties of a polymer electrolyte membrane make it difficult to operate a cell at temperatures above 150 C. With a membrane made of other materials, such as a ceramic material like beta-alumina, it is possible to operate a cell at temperatures above 200° C.
  • electrochemical cell of present invention at atmospheric pressure.
  • the cell could be run at differential pressure gradients, which change the transport characteristics of water or other components in the cell, including the membrane.

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Abstract

L'invention porte sur un élément électrochimique et un procédé d'utilisation d'un halogénure d'hydrogène pour la scission d'une solution de sulfate et de production d'une solution d'hydroxyde, d'acide sulfurique et un halogène gazeux. La solution de sulfate peut en particulier consister en une solution de sulfate de métal alcalin (sodium ou potassium), en une solution de métal alcalino-terreux, ou en une solution de sulfate d'ammonium. L'élément et le procédé peuvent recourir à un halogénure d'hydrogène anhydre ou aqueux par exemple du chlorure ou du fluorure d'hydrogène dans l'option anhydre, ou du bromure ou de l'iodure d'hydrogène ou à un halogène gazeux sec tel que le chlore, le fluor, le brome ou l'iode pour produire des ions hydrogène servant à scinder la solution de métal alcalin pour donner de l'acide sulfurique. L'élément comporte deux systèmes de membranes dans lesquels une anode (12) est en contact avec une membrane (18) et une cathode (20), en contact avec une autre membrane (19), la solution de sulfate étant introduite entre les ensembles membrane-électrode.
PCT/US1995/016123 1995-05-01 1995-12-13 Element electrochimique et procede de separation d'une solution de sulfate et de production d'une solution d'hydroxyde, de l'acide sulfurique et un halogene gazeux WO1996034997A1 (fr)

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AU44213/96A AU4421396A (en) 1995-05-01 1995-12-13 Electrochemical cell and process for splitting a sulfate sol ution and producing a hydroxide solution, sulfuric acid and a halogen gas

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US43160595A 1995-05-01 1995-05-01
US08/431,605 1995-05-01

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2073251A (en) * 1980-04-02 1981-10-14 Gen Electric Anode for reducing oxygen generation in the electrolysis of hydrogen chloride
US4561945A (en) * 1984-07-30 1985-12-31 United Technologies Corporation Electrolysis of alkali metal salts with hydrogen depolarized anodes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2073251A (en) * 1980-04-02 1981-10-14 Gen Electric Anode for reducing oxygen generation in the electrolysis of hydrogen chloride
US4561945A (en) * 1984-07-30 1985-12-31 United Technologies Corporation Electrolysis of alkali metal salts with hydrogen depolarized anodes

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