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WO1998000582A2 - Systeme et procede pour produire de l'hydrogene dans une cellule electrochimique, et pile a combustible alimentee en hydrogene - Google Patents

Systeme et procede pour produire de l'hydrogene dans une cellule electrochimique, et pile a combustible alimentee en hydrogene Download PDF

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Publication number
WO1998000582A2
WO1998000582A2 PCT/US1997/010871 US9710871W WO9800582A2 WO 1998000582 A2 WO1998000582 A2 WO 1998000582A2 US 9710871 W US9710871 W US 9710871W WO 9800582 A2 WO9800582 A2 WO 9800582A2
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WIPO (PCT)
Prior art keywords
cathode
anode
fuel cell
membrane
electrochemical cell
Prior art date
Application number
PCT/US1997/010871
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English (en)
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WO1998000582A3 (fr
Inventor
Francisco Jose Freire
Kenneth Bernard Keating
Dennie Turin Mah
William H. Zimmerman
David Lee Reichert
Aaron Jay Becker
Clarence Garlan Law, Jr.
James Arthur Trainham
Original Assignee
E.I. Du Pont De Nemours And Company
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Application filed by E.I. Du Pont De Nemours And Company filed Critical E.I. Du Pont De Nemours And Company
Publication of WO1998000582A2 publication Critical patent/WO1998000582A2/fr
Publication of WO1998000582A3 publication Critical patent/WO1998000582A3/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
    • 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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • 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
    • 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
    • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
    • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
    • H01M8/0656—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants by electrochemical means
    • 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 a process and an electrochemical cell which produces hydrogen gas and a fuel cell which is powered by the hydrogen gas.
  • Hydrogen chloride (HCl) 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 co-product of these processes. Because 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 HCl by-product.
  • the present invention solves the problems of the prior art by providing a system which converts anhydrous hydrogen halide to halogen gas and hydrogen gas, and which uses the hydrogen gas to power a fuel cell.
  • a system may be used to convert either anhydrous or aqueous or liquid hydrogen halide to halogen gas.
  • a benefit of the present invention is that it avoids environmental problems associated with disposing of HCl, or any hydrogen halide co- product .
  • a further benefit of the present invention is that electric power is produced without consuming fossil or nuclear fuels or atmospheric pollutants.
  • the present invention affords a method of converting hydrogen gas to clean energy.
  • the electrochemical cell may be either a cell for converting anhydrous or liquid or aqueous hydrogen halide to halogen gas.
  • Fig. 1 is a schematic diagram of the system according to the present invention for producing hydrogen gas in an electrochemical cell, where that hydrogen gas is used to power a fuel cell .
  • Fig. 2 is a schematic diagram showing the details of an electrochemical cell for producing halogen gas from anhydrous hydrogen halide according to the present invention.
  • Fig. 2A is a cut-away, top cross-sectional view of the anode and cathode mass flow fields as shown in Fig. 2. DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • the system of the present invention is shown generally at 10 in Fig. 1.
  • the system includes an electrochemical cell which produces hydrogen gas from hydrogen halide.
  • Such a cell is shown in Figs. 1 and 2 generally at 100.
  • anhydrous hydrogen chloride is converted to dry chlorine gas will be described with respect to Figs. 1, 2 and 2A.
  • the present invention may be used w th an electrochemical cell for converting an electrochemical cell for any converting hydrogen halide, i.e., hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, whether anhydrous or aqueous.
  • hydrogen halide i.e., hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, whether anhydrous or aqueous.
  • an inlet line 12 brings in hydrogen halide to the anode-side of electrochemical cell 100.
  • the electrochemical cell of the present invention comprises inlet means for supplying hydrogen halide to the cell.
  • the inlet means comprises an anode-side inlet 102 as shown in Figs. 1 and 2 which supplies anhydrous hydrogen chloride (i.e., in vapor or molecular form) to the cell.
  • the electrochemical cell of the present invention comprises means for oxidizing hydrogen halide to produce protons and halogen gas.
  • the oxidizing means comprises an electrode, or more specifically, an anode 104 as shown in Figs. 1, 2 and 2A.
  • the electrochemical cell of the present invention also outlet means for releasing the halogen gas.
  • the outlet means comprises an anode-side outlet 106 as shown in Figs . 1 and 2. A portion of the hydrogen halide may be unreacted, and this unreacted portion leaves the electrochemical cell through the anode-side outlet, along with the halogen gas.
  • the halogen gas such as chlorine gas, leaves the cell through a line 14 as shown in Fig. 1.
  • the electrochemical cell of the present invention also comprises cation-transporting means for transporting the protons therethrough, wherein the oxidizing means is disposed in contact with one side of the cation-transporting means.
  • the cation-transporting means is a cation-transporting membrane 108, where the anode is disposed in contact with one side of the membrane as shown in Figs. 1, 2 and 2A.
  • membrane 108 may be a proton-conducting membrane.
  • the membrane acts as the electrolyte.
  • the membrane may be a commercial cationic membrane made of a fluoro- or perfluoropolymer, preferably a copolymer of two or more fluoro or perfluoromonomers , at least one of which has pendant sulfonic acid groups.
  • 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 the patent literature. They include fluorinated polymers with side chains of the type —CF 2 CFRS0 3 H and —OCF 2 CF 2 CF 2 SO 3 H, where R is an F, Cl, CF 2 C1, or a C ⁇ to C 10 perfluoroalkyl radical.
  • those resins may be in the form that has pendant —S0 F groups, rather than —S0 3 H groups.
  • the sulfonyl fluoride groups can be hydrolyzed with potassium hydroxide to —S0 3 K groups, which then are exchanged with an acid to —S0 3 H groups.
  • Suitable perfluorinated cationic membranes which are made of hydrated copolymers of polytetrafluoroethylene and poly-sulfonyl fluoride vinyl ether-containing pendant sulfonic acid groups, are offered DuPont under the trademark "NAFION ® " (hereinafter referred to as NAFION ® ) .
  • NAFION ® membranes containing pendant sulfonic acid groups include NAFION ® 115,
  • NAFION ® 117, NAFION ® 324 and NAFION ® 417 The first and second types of NAFION ® are unsupported and have 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.
  • NAFION ® 324 and NAFION ® 417 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.
  • NAFION ® 115 in particular may be used with the electrochemical cell of the present invention.
  • Beta-alumina is a class of nonstoichiometric crystalline compounds having the general structure Na 2 O x -Al 2 ⁇ 3 , ⁇ n which x ranges from 5 00 ( ⁇ "-alumina) to 11 ( ⁇ -alumina) . This material and a number of solid electrolytes which are useful for the invention are described in the Fuel Cell Handbook, A. J. Appleby and F. R. Foulkes, Van Nostrand
  • the electrochemical cell of the present invention also comprises means for reducing the transported protons, where the reducing means is disposed in contact with the other side of the cation-transporting means.
  • the reducing means comprises an electrode, or more specifically, a cathode 110, where cathode 110 is disposed in contact with the other side (as opposed to the side which is in contact with the anode) of membrane 108 as illustrated in Figs. 1, 2 and 2A.
  • the membrane of the electrochemical cell of the present invention When converting anhydrous hydrogen halide to dry halogen gas, the membrane of the electrochemical cell of the present invention must be kept hydrated in order to keep the conductivity of the membrane high and to increase the efficiency of proton transport through the membrane. This hydration is accomplished by supplying liquid water to the cathode-side of the membrane.
  • the electrochemical cell of the present invention also comprises cathode-side inlet means for supplying water to the membrane.
  • the cathode-side inlet means comprises a cathode-side inlet 112 as shown in Figs. 1 and 2.
  • the electrochemical cell of the present invention also includes a cathode chamber disposed adjacent the reducing means.
  • a cathode chamber is shown at 105 in Figs. 2 and 2A disposed adjacent to, meaning next to or near, the reducing means, or cathode.
  • the cathode-side inlet is disposed in fluid communication with the cathode chamber.
  • the cathode- side inlet is connected to a recycle line 16 as shown in Fig. 1. It should be noted that if the electrochemical cell of the present invention is used to convert aqueous hydrogen chloride to wet chlorine gas, then the electrochemical cell of the present invention does not include a cathode-side inlet or a recycle line for recycling water to the membrane.
  • the electrochemical cell of the present invention also comprises cathode-side outlet means also disposed in fluid communication with the cathode chamber.
  • the cathode-side outlet means comprises a cathode-side outlet 114 as shown in Fig. 1 or a cathode-side outlet 114 as shown in Fig. 2.
  • a passage 115 as shown in Fig. 2 is formed between the anode-side inlet and the cathode-side outlet, and a similar passage 117 is shown formed between the cathode-side inlet and the anode-side outlet.
  • These passages carry the reactants into and the products out of the cell through the anode and cathode-side inlets, and the anode and cathode-side outlets, as will be further explained below .
  • the anode and the cathode comprise an electrochemically active material.
  • 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 electrochemically active material may comprise a catalyst material such as platinum, ruthenium, osmium, rhenium, rhodium, iridium, palladium, gold, titanium, tin or zirconium and the oxides, alloys or mixtures thereof.
  • 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 anode and the cathode may be porous, gas- diffusion electrodes.
  • Gas diffusion electrodes provide the advantage of high specific surface area, as known to one skilled in the art.
  • a particular type of gas diffusion electrode, known as an ELAT may be used as the anode and the cathode.
  • An ELAT comprises a support structure, as well as the electrochemically active material.
  • an ELAT comprising a support structure of carbon cloth and electrochemically active material comprising ruthenium oxide, commercially available from E-TEK, of Natick, Massachusetts, may be used.
  • an ELAT may be used which comprises a catalyst material mixed with carbon and particles of polytetrafluoroethylene, or PTFE, a tetrafluoropolymer resin which is sold under the trademark "TEFLON ® “ (hereinafter referred to as "PTFE”), commercially available from DuPont .
  • PTFE polytetrafluoroethylene
  • the catalyst material, carbon particles and PTFE are then sintered on a carbon cloth substrate, which is treated with a NAFION ® solution. This ELAT is held mechanically against the membrane of the cell.
  • the electrochemically active material may be used for the anode and cathode of the present invention.
  • the electrochemically active material may be disposed adjacent, meaning at or under, the surface of the cation-transporting membrane.
  • the electrochemically active material may be deposited into the membrane, as shown in U.S. Patent No. 4,959,132 to Fedkiw.
  • a thin film of the electrochemically active material may be applied directly to the membrane.
  • the electrochemically active material may be hot-pressed to the membrane, as shown in A. J. Appleby and E. B. Yeager, Energy, Vol. 11, 137 (1986). If the electrodes are hot-pressed into the membrane, they have the advantage of having good contact between the catalyst and the membrane.
  • the electrochemically active material may comprise a catalyst material on a support material.
  • the support material may comprise particles of carbon and particles of PTFE.
  • the electrochemically active material may be bonded by virtue of the PTFE to a support structure of carbon cloth or paper or graphite paper and hot-pressed to the cation- transporting membrane.
  • the hydrophobic nature of PTFE 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 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 .
  • a thin film of the electrochemically active material is applied directly to the membrane to form a catalyst-coated membrane.
  • the membrane is typically formed from a polymer as described above in its sulfonyl fluoride form, since it is thermoplastic in this form, and conventional techniques for making films from thermoplastic polymer can be used.
  • the electrochemically active material is conventionally incorporated in a coating formulation, or "ink", which is applied to the membrane.
  • the coating formulation, and consequently the anode and the cathode after the catalyst coated membrane is formed also comprises a binder polymer for binding the particles of the electrochemically active material together.
  • the solvent can be a variety of solvents, such as FLUORINERT FC-40, commercially available from 3M of St. Paul, Minnesota, which is a mixture of perfluoro (methyl-di-n-butyl) amine and perfluoro (tri-n- butylamine) .
  • FLUORINERT FC-40 commercially available from 3M of St. Paul, Minnesota
  • a copolymer polymerized from tetrafluoroethylene and a vinyl ether which is represented by the formula
  • CF 2 CF-0-CF 2 CF(CF 3 ) -0-CF 2 CF 2 S0 2 F has been found to be a suitable binder polymer.
  • ruthenium dioxide has been found to be a suitable catalyst.
  • the sulfonyl fluoride form has been found to be compatible with FC-40 and to give a uniform coating of the ruthenium dioxide catalyst on the membrane.
  • the electrochemical cell must include a gas diffusion layer (not shown) disposed in contact with the anode and the cathode, respectively, (or at least in contact with the anode) , on the side of the anode or cathode opposite the side which is in contact with the membrane.
  • the gas diffusion layer provides a porous structure that allows the hydrogen halide, and specifically, the anhydrous hydrogen halide, or the hydrogen chloride, to diffuse through to the layer of electrochemically active material of the catalyst- coated membrane.
  • both the anode gas diffusion layer and the cathode gas diffusion layer distribute current over the electrochemically active material, or area, of the catalyst-coated membrane.
  • the diffusion layers are preferably made of graphite paper, and are typically 15 - 20 mil thick.
  • the electrochemical cell of the present invention further comprises an anode flow field 116 disposed in contact with the anode and a cathode flow field 118 disposed in contact with the cathode as shown in Figs. 2 and 2A.
  • the flow fields are electrically conductive, and act as both mass and current flow fields.
  • the anode and the cathode flow fields comprise porous graphite paper.
  • Such flow fields are commercially available from Spectracorp, of Lawrence, Massachusetts.
  • the flow fields may be made of any material and in any manner known to one skilled in the art.
  • the flow fields may alternatively be made of a porous carbon in the form of a foam, cloth or matte.
  • the anode mass flow field includes a plurality of anode flow channels 120
  • the cathode mass flow field includes a plurality of cathode flow channels 122 as shown in Fig.
  • the channels of the anode mass flow field and the channels of the cathode mass flow field are parallel to each other, and more particularly, are vertical and parallel to each other.
  • the anode flow fields and the anode flow channels get reactants, such as anhydrous hydrogen chloride, to the anode and products, such as dry chlorine gas, as well as any unreacted hydrogen halide, such as unreacted hydrogen chloride, from the anode.
  • the cathode flow field and the cathode flow channels get catholyte, such as liquid water to the membrane in the case where anhydrous hydrogen halide is converted and products, such as hydrogen gas and water, from the cathode.
  • the electrochemical cell of the present invention may also comprise an anode-side gasket 124 and a cathode-side gasket 126 as shown in Fig. 2.
  • Gaskets 124 and 126 form a seal between the interior and the exterior of the electrochemical cell.
  • the anode-side gas is made of a fluoroelastomer , sold under the trademark VITON ® (hereinafter referred to as VITON ® ) by DuPont Dow Elastomers L.L.C. of Wilmington, Delaware.
  • the cathode-side gasket may be made of the terpolymer ethylene/propylene/diene (EPDM) , sold under the trademark NORDEL ® by DuPont, or it may be made of VITON ® .
  • the electrochemical cell of the present invention also comprises an anode current bus 128 and a cathode current bus 130 as shown in Fig. 2.
  • the current buses conduct current to and from a voltage source (not shown) .
  • anode current bus 128 is connected to the positive terminal of a voltage source through a line 20 as shown in Fig. 1
  • cathode current bus 130 is connected to the negative terminal of the voltage source through a line 22 as shown in Fig. 1, so that when voltage is applied to the cell, current flows through all of the cell components to the right of current bus 128 as shown in Fig. 2, including current bus 130, 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 may further comprise an anode current distributor 132 as shown in Fig. 2.
  • the anode current distributor collects current from the anode current bus and distributes it to the anode by electronic conduction.
  • the anode current distributor may comprise a fluoro- polymer which has been loaded with a conductive material.
  • the anode current distributor may be made from polyvinylidene fluoride, sold under the trademark KYNAR® (hereinafter referred to as "KYNAR®”) by Elf Atochem North America, Inc. Fluoropolymers, and graphite.
  • the electrochemical cell of the present invention may further comprise a cathode current distributor 134 as shown in Fig. 2.
  • the cathode current distributor collects current from the cathode and for distributing current to the cathode bus by electronic conduction.
  • the cathode distributor also provides a barrier between the cathode current bus and the cathode and the hydrogen chloride.
  • the cathode current distributor may comprise a fluoropolymer, such as KYNAR®, which has been loaded with a conductive material, such as graphite.
  • the electrochemical cell of the present invention also includes an anode-side stainless steel backer plate (not shown) , disposed on the outside of the cell next to the anode current distributor, and a cathode- side stainless steel backer plate (also not shown) , disposed on the outside of the cell next to the cathode current distributor.
  • These steel backer plates have bolts extending therethrough to hold the components of the electrochemical cell together and add mechanical stability thereto.
  • a voltage in the range of 1.0 to 2.0 volts may be applied.
  • a current density of greater than 5.38 kA/m 2 (500 amps/ft 2 ) may be achieved at a voltage of 2 voltes or less.
  • a current density in the range of 8 - 16 kA/m 2 or greater may be achieved, with 8 - 12 kA/m 2 being the average range for current density at a voltage of 1.8 to 2.0 volts.
  • the current efficiency that is, the amount of electrical energy consumed in converting anhydrous hydrogen halide to halogen gas, of the electrochemical cell of the present invention, is on the order of 98% - 99%.
  • the electrochemical cell has a utility, that is, conversion per pass, or mole fraction of anhydrous hydrogen halide converted to essentially dry halogen gas per single pass in the range of 50% - 90%, with 70% being the average.
  • the amount of water, in the vapor state, in the anolyte outlet due to membrane hydration is less than 400 parts per million (ppm) , and is typically in the range of 200 - 400 ppm.
  • the electrochemical cell of the present invention can be operated at higher temperatures at a given pressure than electrochemical cells of the prior art which convert aqueous hydrogen chloride to chlorine . This affects the kinetics of the reactions and the conductivity of the membrane. Higher temperatures result in lower cell voltages. However, limits on temperature occur because of the properties of the materials used for elements of the cell. For example, 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 approaching 150°C. Thus, a range of operating temperatures for a polymer electroylyte membrane is 40°C - 120°C.
  • the system of the present invention also comprises a fuel cell connected to the outlet means of the electrochemical cell and powered by the hydrogen gas produced by the electrochemical cell .
  • a fuel cell according to the present invention is shown generally at 200 in Fig. 1.
  • Fuel cell 200 comprises a membrane 210, and an anode 204 and a cathode 210 disposed in contact with the membrane.
  • the anode, cathode and membrane may be constructed as discussed above for the electrochemical cell.
  • the fuel cell of the present invention also has a fuel-cell anode side inlet 206 for supplying the hydrogen gas to the anode of the fuel cell .
  • the hydrogen gas is sent from the electrochemical cell to the fuel cell through a line, such as line 17 as shown in Fig. 1.
  • the fuel cell also has a fuel cell cathode-side inlet 212 for supplying an oxygen- containing gas, or oxidant, such as oxygen or air, to the fuel cell membrane.
  • Fuel cell 200 operates like any fuel cell known n the art, where power is produced, and water and air are produced in the fuel cell .
  • the system of the present invention thus further includes a fuel cell cathode-side outlet 214 for releasing water and air from the fuel cell .
  • the hydrogen and the oxidant enter the respective inlets and penetrate the electrodes, which are porous, to contact the surface of the membrane.
  • the electrodes On the anode, or hydrogen side of the fuel cell, electrons are given up and the hydrogen ions migrate to the cathode chamber, where they combine with returning electrons in the presence of oxygen to form water. Water is formed in the cathode chamber and is carried out through outlet 214. If air is the oxidant, outlet 214 is also employed to remove nitrogen which builds up.
  • the fuel cell thus produces DC power.
  • a benefit of the present invention is that electric power is produced without consuming fossil or nuclear fuels or atmospheric pollutants.
  • the present invention affords a method of converting hydrogen gas to clean energy.
  • the DC power produced by the fuel cell may be used to supplement the total power required to run the electrochemical process which is occurring in cell 100.
  • the DC power produced by the fuel cell may be used to run any electrochemical process, or indeed any process, which consumes electrical energy.
  • the positive terminal of the electrochemical cell may connected to the positive terminal of the fuel cell by an electronic conductor, such as a cable, wire or bus bar.
  • the negative terminal of the electrochemical cell is connected to the negative terminal of the fuel cell by an electronic conductor, such as a cable, wire or bus bar.
  • Th s hook-up delivers the electric power produced by the fuel cell back to the electrochemical cell, thereby providing a portion of the power necessary to run the process.
  • the rest of the power necessary to run the process may be provided by a voltage rectifier, not shown, which converts conventionally supplied AC power to DC power, which is compatible to that produced by the fuel cell.
  • a process for powering a fuel cell from hydrogen gas produced by the conversion of hydrogen halide produced in an electrochemical cell This process will be described with respect to the conversion of anhydrous hydrogen chloride to dry chlorine gas, although it should be understood that it may also apply to the conversion of any hydrogen halide to halogen gas, either anhydrous or aqueous.
  • this process will be described with respect to the system of Fig. 1, although the process should not be limited in any way to the elements shown in Fig. 1.
  • a voltage is applied to the anode and the cathode of an electrochemical cell, such as cell 100, so that the anode is at a higher potential than the cathode, and current flows to an anode bus, such as anode bus 132.
  • An anode current distributor such as distributor 128, collects current from the anode bus and distributes it, to the anode by electronic conduction.
  • Anhydrous hydrogen chloride gas which is in molecular or vapor form, or aqueous hydrogen chloride, is fed to an anode-side inlet, such as inlet 102, and through flow channels in an anode mass flow field, such as channels 120 in flow field 116.
  • Hydrogen chloride is transported to the surface of anode 104. Hydrogen chloride is oxidized at the anode under the potential created by the voltage source to produce essentially dry chlorine gas at the anode, and protons (H + ) . This reaction is given by the equation:
  • the membrane of the electrochemical cell must be hydrated in order to have efficient proton transport and to increase the efficiency of proton transport through the membrane.
  • water is delivered to the cathode through a cathode-side inlet, such as inlet 112 as shown in Fig. 2 and through the channels in cathode mass flow field, such as channels 120 in cathode mass flow field 116 to hydrate the membrane and thereby increase the efficiency of proton transport through the membrane.
  • the hydrogen which is evolved at the interface between the cathode and the membrane exits via cathode-side outlet, such as outlet 114 as shown in Fig. 1.
  • the hydrogen bubbles through the water and is not affected by the electrode.
  • a cathode current distributor such as distributor 134 as shown in Fig. 2, collects current from the cathode and distributes it to a cathode bus, such as bus 130 as shown in Fig. 2.
  • the hydrogen gas and water which are released from the electrochemical cell are sent to a fuel cell, where, further in accordance with the process of the present invention, the hydrogen gas is used to power the fuel cell, which produces DC power.
  • the hydrogen gas and water are sent to a fuel-cell anode side inlet, such as inlet 206.
  • An oxygen-containing gas, or oxidant, such as oxygen or air is supplied to the cathode-side inlet of the cell.
  • power, as well as water and air are produced.
  • the water and air are released from the fuel cell through a cathode-side outlet, such as outlet 214 as shown in Fig. 1.
  • the hydrogen and the oxidant enter the respective inlets and penetrate the electrodes, which are porous, to contact the surface of the membrane.
  • electrons are given up and the hydrogen ions migrate to the cathode chamber, where they combine with returning electrons in the presence of oxygen to form water.
  • the water is formed in the cathode chamber and is carried out through the cathode-side outlet. If air is the oxidant, the cathode-side outlet is also employed to remove nitrogen which builds up. The fuel cell thus produces DC power.
  • the DC power produced by the fuel cell may be used to supplement the total power required by the electrochemical process which occurs in cell 100.
  • the DC power produced by the fuel cell may be used to run any electrochemical process, or indeed any process, which consumes electrical energy.
  • the use of the DC power produced by the fuel cell to supplement the total power required by the electro- chemical cell is accomplished by the configuration described above with respect to the system of the present invention.

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Abstract

L'invention concerne un procédé et une cellule électrochimique pour produire de l'hydrogène, et une pile à combustible qui est alimentée en hydrogène. La cellule électrochimique transforme l'halogénure d'hydrogène, comme le chorure d'hydrogène anhydre ou aqueux, en chlore sec ou mouillé, respectivement. La pile à combustible génère une énergie sous forme d'un courant direct qui peut être utilisé pour diverses applications, qui peuvent comprendre l'alimentation de la cellule électrochimique produisant l'hydrogène.
PCT/US1997/010871 1996-06-28 1997-06-23 Systeme et procede pour produire de l'hydrogene dans une cellule electrochimique, et pile a combustible alimentee en hydrogene WO1998000582A2 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
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US7201782B2 (en) 2002-09-16 2007-04-10 Hewlett-Packard Development Company, L.P. Gas generation system

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US4689133A (en) * 1985-03-29 1987-08-25 The Dow Chemical Company Directly electrically coupled fuel cell-electrolysis cell system
US5443804A (en) * 1985-12-04 1995-08-22 Solar Reactor Technologies, Inc. System for the manufacture of methanol and simultaneous abatement of emission of greenhouse gases
US5041197A (en) * 1987-05-05 1991-08-20 Physical Sciences, Inc. H2 /C12 fuel cells for power and HCl production - chemical cogeneration
US5411641A (en) * 1993-11-22 1995-05-02 E. I. Du Pont De Nemours And Company Electrochemical conversion of anhydrous hydrogen halide to halogen gas using a cation-transporting membrane

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7201782B2 (en) 2002-09-16 2007-04-10 Hewlett-Packard Development Company, L.P. Gas generation system

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