CA1187442A - Permionic membrane electrolytic cell current distribution means - Google Patents
Permionic membrane electrolytic cell current distribution meansInfo
- Publication number
- CA1187442A CA1187442A CA000388583A CA388583A CA1187442A CA 1187442 A CA1187442 A CA 1187442A CA 000388583 A CA000388583 A CA 000388583A CA 388583 A CA388583 A CA 388583A CA 1187442 A CA1187442 A CA 1187442A
- Authority
- CA
- Canada
- Prior art keywords
- permionic membrane
- cathode
- electrocatalyst
- permionic
- inch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- C25B13/00—Diaphragms; Spacing elements
-
- 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
- C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
- C25B1/46—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in diaphragm cells
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
ABSTRACT
Disclosed is an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with 8 cathode therein, and a permionic membrane therebetween. The cathode contacts the permionic mem-brane, with the cathodic surface of the permionic membrane having a current distributing material, i.e., a conductive, substantially non-electrocatalytic material, dispersed across the face thereof.
Disclosed is an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with 8 cathode therein, and a permionic membrane therebetween. The cathode contacts the permionic mem-brane, with the cathodic surface of the permionic membrane having a current distributing material, i.e., a conductive, substantially non-electrocatalytic material, dispersed across the face thereof.
Description
PERMIONIC ~EMBRANE ELECTROLYTIC CELL CURRE~T DISTRIBUTION MEANS
DESCRIPTION OF T~E INVENTION
Permionic membrane electrolytic cells, including zero gap permi-onic membrane electrolytic cells, have a ca~ion s~lective permionic membrane.
The cation selective permionic membrane separates the anolyte compartment, with an anode therein, Erom the catholyte compartment, with a cathode therein. In a ~ero gap permionic membrane electrolytic cell the anodic electrocatalyst and the cathodic electrocatalyst are in contact with the respective faces of the permionic membrane. In a solid polymer electrolyte electrolytic cell the anodic electrocatalyst and cathodic electrocatalyst ure bonded to and embedded in the permionic membrane.
The zero gap permionic membrane electrolytic cell offers the advantage of ready removability of the electrocatalyst. That i8, the n~odic and cathodic electrocatalyst can be removed from contact with the permionic membrane without destruction or degradation of the permionic membrane. Another advantage offered by æero gap pe~mionic membrane elec- -trolytic cell~ over solid polymer electrolyte electrolytic cells i~ the higher current efficiency of the zero gap permionic membrane electrolytic cell. Ho~ever, the higher current efficiency com2s at a penalty of a higher cell voltage.
According to the invention herein contemplated, it has now been found that the v~ltage of a zero gap permionic membranç electrolytic cell may be reduced if there is present in and on the cathodic surface of the ~~
permionic membrane, ~uitable current distribution mPan6~ ~h~r~by to enhance electronic conduction across the cathodic surface of the permionic membrane.
A~ herein conte~plated, the cathode contact~ the permionic membrane with the cathode ~urface of the permionic membrane having curreDt distribution msterial, i.e~, conductive, substantislly non-catalytic materials, dis-persed acro83 the cathodic surface of the permionic membrane. The non-ca~alytic ~aterial may be bonded ~o and embedded in the ca~hodic surface of the per~ionie m~brane.
DETAILED DESCRIPTION OF THF, INVENTION
_ ~ erein contemplated is an electrolytic cell having an anolyte comp~rtment with an snode therein, a catholyte compartment with a caehode therein, and a permionic membrane ther~between, with at le~st the cathode contacting the permionic ~embrane. The per~ionic me~brane i~ characterized by its cathodic surface having electrically cond~ctive, substantially non-electrocataly~ic material in contact therewith, and either adherent thereto or adherent to the cathodic electroc~taly~t. By sub~tantially non-catalytic material it ic meant that the material serve~ the purpose of an electronic current distributor, having a metallic e'Lectrical conductivity, but havin~
8 high hydrogen evolution overvoltage, i.e., at least ~bout 0.1 volt higher than the hydrogen evolution overvoltage of the cathodic electro~atalyst used in combination therewith.
More particularly, the invention provides a method of electrolyzing an alkali metal chloride br~ne in an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with a cathode therein, and a o~rmioni~ membran~ therebetween, said cathode contacting Lhe permionic membrane, ~hich method comprises passing an electrical current from the anode to the cathode, evolving chlorine at the anode and hydroxyl ion at the cathode; the improvement wherein said cathode comprises a Group VIII
transition metal as the electrocatalyst, said permionlc membrane has an anodic surface and a cathodic surface, the cathodic surface thereof havinr electrically conductive, substantially non-electrocatalytic particles of material chosen from the group consisting of Group IB metals and corrosion resistant, electrically conductive compounds thereof bonded thereto, the
DESCRIPTION OF T~E INVENTION
Permionic membrane electrolytic cells, including zero gap permi-onic membrane electrolytic cells, have a ca~ion s~lective permionic membrane.
The cation selective permionic membrane separates the anolyte compartment, with an anode therein, Erom the catholyte compartment, with a cathode therein. In a ~ero gap permionic membrane electrolytic cell the anodic electrocatalyst and the cathodic electrocatalyst are in contact with the respective faces of the permionic membrane. In a solid polymer electrolyte electrolytic cell the anodic electrocatalyst and cathodic electrocatalyst ure bonded to and embedded in the permionic membrane.
The zero gap permionic membrane electrolytic cell offers the advantage of ready removability of the electrocatalyst. That i8, the n~odic and cathodic electrocatalyst can be removed from contact with the permionic membrane without destruction or degradation of the permionic membrane. Another advantage offered by æero gap pe~mionic membrane elec- -trolytic cell~ over solid polymer electrolyte electrolytic cells i~ the higher current efficiency of the zero gap permionic membrane electrolytic cell. Ho~ever, the higher current efficiency com2s at a penalty of a higher cell voltage.
According to the invention herein contemplated, it has now been found that the v~ltage of a zero gap permionic membranç electrolytic cell may be reduced if there is present in and on the cathodic surface of the ~~
permionic membrane, ~uitable current distribution mPan6~ ~h~r~by to enhance electronic conduction across the cathodic surface of the permionic membrane.
A~ herein conte~plated, the cathode contact~ the permionic membrane with the cathode ~urface of the permionic membrane having curreDt distribution msterial, i.e~, conductive, substantislly non-catalytic materials, dis-persed acro83 the cathodic surface of the permionic membrane. The non-ca~alytic ~aterial may be bonded ~o and embedded in the ca~hodic surface of the per~ionie m~brane.
DETAILED DESCRIPTION OF THF, INVENTION
_ ~ erein contemplated is an electrolytic cell having an anolyte comp~rtment with an snode therein, a catholyte compartment with a caehode therein, and a permionic membrane ther~between, with at le~st the cathode contacting the permionic ~embrane. The per~ionic me~brane i~ characterized by its cathodic surface having electrically cond~ctive, substantially non-electrocataly~ic material in contact therewith, and either adherent thereto or adherent to the cathodic electroc~taly~t. By sub~tantially non-catalytic material it ic meant that the material serve~ the purpose of an electronic current distributor, having a metallic e'Lectrical conductivity, but havin~
8 high hydrogen evolution overvoltage, i.e., at least ~bout 0.1 volt higher than the hydrogen evolution overvoltage of the cathodic electro~atalyst used in combination therewith.
More particularly, the invention provides a method of electrolyzing an alkali metal chloride br~ne in an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with a cathode therein, and a o~rmioni~ membran~ therebetween, said cathode contacting Lhe permionic membrane, ~hich method comprises passing an electrical current from the anode to the cathode, evolving chlorine at the anode and hydroxyl ion at the cathode; the improvement wherein said cathode comprises a Group VIII
transition metal as the electrocatalyst, said permionlc membrane has an anodic surface and a cathodic surface, the cathodic surface thereof havinr electrically conductive, substantially non-electrocatalytic particles of material chosen from the group consisting of Group IB metals and corrosion resistant, electrically conductive compounds thereof bonded thereto, the
- 2 -7~2 particles havlng a hydrogen evolution overvoltage at least 0.1 volt higher than tha hydrogen overvoltage of the electrocatalyst.
Preferably, the elec~ricslly conductive, Rub~tantially non-catslytic material i~ chosen Erom the group con3isting of Group IB metals ant corrosion re6i~ant, electrically conductive, but ~ub~tantially non-electrocatalytic compounds thereof. These ~sterials include copper, silv~r, and gold, as well as those oxides thereof that are seable in the aqueous, slkali ~e~al hydroxide envison~ent. Especially preferred, for reu~ons of co~t, availabili~y, and lo~ electrocatalytic ac~iviey, are silver oxide, silver, and copper.
- 2a The electrically conductive~ substantially non-electrocatalytic material may be a particulate material, for example, particles having a particle size of ~rom about 0.1 micron ~o about minus 2~0 me~h and prefera-bly from about 0.5 micron to about minus 325 mesh. The substantially non-electrocatalytic, electrically conductive material is preferably adherent to the permionic membrane. That i8, it i6 preferably bondsd to and embedded in the permionic membrane, and substantially non-removable therefrom with-out degradation, partial destruction, or de~truction of either the material or the permionic membrane, or both. Alternatively, especially when the non-catalytic material is of a finer mesh si~e than the electrocatalyst, it may be adherent to either the electrocatalyst or to the substrate carrying the electrocataLyst, as where the electrocatalyst i8 a particulate electro-catalyst bonded to a metallic substrate, with particulate conductor material on the substrate, and between and on the e'Lectrocatalyst particles.
Typicfllly, the cathode electrocal:alyst of the electrolytic cell is a Group VIII transition metal, having a lower hydrogen evolution over-voltage than ~he electrically conductive, l3ubstsntially non-electrocatalytic material. Typical cathodic electrocatalysts include iron, cobalt, nickel and the platinum group metals, especially electrocPlly catalytic forms such as Raney nickel, platini~ed platinum, and platinum black.
According to an alternative exemplification of the method of this invention, there i8 provided a method of electrolyzing an alkali metal chloride brine in an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with a cathode therein, and a permionic mambrane therebetween. The cathode contacts the permionic membrane, preferably and removably, that is readily removable without destruction or degradation of either the cathodlc electrocatalyst or the 7~2 permionic membrane. As herein contempla~e~, the process comprises passing an electrical current from the anode to the cathode, whereby to evolve chlorine at the anode and hydroxyl ion at the cathode. The method is characteri~ed in that the permionic membrane has on its cathodic aurface electrically conductive, sub~tantially non-electrocatalytic material either adherent thereto or in contac therewith J as descrihed ~bove.
Accordin~ to one exemplification herein contemplated, the current distributor may be bonded to the cathodic surface of the permionic membrane alone, that i8, without electrocatalyst being present thereon. In this way, the electrocatalyst is readily removable from the surface, and i9 present on a separate electrode structure, i.e., a metallic screen, mesh, shee, plate, or the like, having a coating, surface, or film of electrocatalyst n~ herein described.
According to an alternative exemplification, the electrocatalyst i~ present as a bilayer, i.e., a~ a second layer, atop the layer, sur- -face, or film of particulate, electrically conductive, substantially non-electrocatalytic ~aterial which is bonded to and embedded in the permionic mernbrane. According to this exemplification, the ~ubstantially non-electrocatalytic, electrically conductive material is applied first to the permionic membrane, and thereafter the electrocatalyst i8 applied thereto, both above and between particles of ~he conductive, non-catalytic material.
According to a 3ill further exemplification of the method of this invention, electrocatalyst may be present on the ~urface of the per-mionic membrane, in admi~ture with the electrically conducti~e, substan-tially non-catalytic material wnich i5 also adherent to the permionic membrane surface.
According to a still further exemplification, the electrocatalyst and the non-catalytic material may bo~h be present on and adherent to an electroconductive subetrate, and removable from the permionic membrane.
Generally the loading of the electronically conductive, current distributor i6 from about 1 milligram per square centimeter to about 100 milligrams per square, and generally from about 2 to about 20 milligrams per square centimeter. Amounts lower than about 1 milligram per gquare centimeter do not provide significant amount~ of current distribution, ~hile amounts greater than about 100 milligrams per square centimeter may ~uhstantially interfere with the electrochemical process, providing an impermeable barrier, sheet, or film on the cathodic surface of the permi-onic membrane.
The permionic membrane interposed between the-anolyte and the porou~ matrix is fabricated of a polymeric fluorocarbon copolymer having immobile, cation selective ion exchange group~ on a halocarbon backbone.
The membrane may b~ from about 2 to about ~S mils thick, although thicker or thinner permionic membranes may be utilized. The permionic membrane may be a laminate of two or more membrane ~heet~. It may, additionally, have internal reinforcing fibers.
The permionic membrane may be a copolymer of (I) a fluorovinyl polyether having pendant ion exchange groups and having the formula (I) CF2~CF-Oa-[(CX'X'')C (CFX')d (CF2-0-(XIX")e (CX"X'0-CF2)~-A
w~ere a is 0 or 1, b i8 0 to 6, c iB 0 to 6, d is 0 to 6, e i8 0 to 6, f i8 0 to 6; X, X', and X" are ~ Cl, -F, and -(CF2)gCF3; g i8 1 to 5, [ ] i8 a discretionary arrangement of the moieties therein; and A is the pendant functional group as will be described hereinbelow. Preferably a i8 1, and X, X' ~nd X" are -F and (CF2)gCF3.
7~
The fluorovinyl polyether may be copolymerized with a (II) fluoro-vinyl compound (II) CF2 = CF~a~(CF~ d) A
and a (III) perfluorinated olefin (III) CF2 - CXX', or (I) may be copolymerized with only a (III~ perfluorinated olefin, or (I) may be copolymerized with only a (II) perfluorovinyl compound.
The functional group is a cation selective group. It may be a sulfonic group, a phosphoric group, a phosphonic group, a carboxylic group, ~ a precursor thereof, or a reaction product thereof, e.g., an ester thereof.
Carboxylic groups, precursor~ thereof, and reactions products thereof are preferred. Thus, as herein contemplated, A is preferably chosen from the group consisting of -COOH, -COOR l, -COOM, -GOF, -COCl, -CN, -CONR2R3 ~
-S03H, -S03M, -S02F, and -S02Cl where Rl is a Cl to Clo alkyl group, R2 and R3 are hydrogen or Cl to Clo alkyl groups, and M i~ an alkali metal or a quaternary ammonium group.
According to a particularly preerrPd exemplification, A is ~7fl~
-COCl, -COO~I, -COORl, -S02F, or -S02Cl where Rl i8 a Cl to Cs alkyl.
As herein contemplated, the permionic membrane i~ preferably a copolymer which may have:
~I) fluorovinyl ether acid moieties derived from CF2=cF-o-lcF2btcxlx~)ctcFx~)tcF2-o-cx~x~i)etcx~x~-o~cF2)f~-A~ -exemplified by CF2=CFOCF2CFtCF30CF3CF2CF2COOOCH3, CF2=CFO(CF2)30CFCOOCH3, CF2=CFotCF2)40CIFCoc~cH3, CF2=CFOCF2CFCF2COOCH3, and CF2=CFOCF2CF(CF3)0CF(COOC~3)CF3, inter alia;
(II) fluorovinyl moieties derived from CF2~CF-to)~,-(CFX' )d-A, exemplified by CF2-CF(CF2)2_4COOCH3 CF2-CF ( CF2 ) 2-4COOCH3 ~
CF~=CFotCF2)2_4CooCH3, CF2 = CFotCF2)2_4CooC2H5~ and CF2 = CFO(CF2)2-4CoOcH3, inter alia;
7~L;~
(III) fluorinated olefin moieties derived from CF = CXX' as exenplified by tetrafluoroethylene, trichlorofluoroethylene, hexafluoropropylene, trifluoroethylene, vinylidene, fluorlde, and the like; and (IV) vinyl ethers derived from CF2 = CFOR4 The permionic membrane herein contemplated has an ion exchange capacity of from about 0.5 to about 2.0 milliequivalentspergram of dry polymer, preferably from about 0.9 to about 1.8 milliequivalents per gram of dry polymer, and in a particularly preferred exemplification, from about 1.0 to about 1.6 milliequivalents per gram of dry polymer. The permionic membrane herein contemplated has a volumetric flow rate of 100 cubic millimeters per second at a temperature of 150 to 300 degrees Centlgrade, and preferably at a temperature between 160 to 250 degrees Centigrade. The glass transition temperature of the permionic membrane polymer is below 70C, and preferably below about 50C.
The permionic membrane herein contemplated may be prepared by the methods described in U.S. Patent 4,126,588.
Most commonly the ion exchange resins will be in a thermoplastic form, i.e., a carboxylic acid ester, e.g., a carboxylic acid ester of methyl, ethyl, propyl, isopropyl, or butyl alcohol, or a sulfonyl halide, e.g., sulfonyl chloride or sulfonyl fluoride, during the fabrication herein contemplated9 and will thereafter be hydrolyzed.
According to one exemplification of this invention, an electro-lytic cell may be assembled having an anode bearing upon the anodic surface of the permionic membrane, and platinum black and silver oxide, Ag2O bonded to the cathodic side of the permionlc membrane. According to this exempliEicatlon, a perfluorocarbon polymer having pendant carboxylic acid ester groups, l.e.~ being in the thermoplastic form, may be coated with a plasticizer, i.e., bis(2-ethyl hexyl) isophthalate, one part platinum black and 4 parts silver oxide, whereby to provide a loading of about 12 milligrams per square centimeter of silver oxide and about 3 milligrams per square centimeter of platinum black. The coated permionic membrane may ~hen be hot pressed, for example from about 180C to about 225C and at a pressure o~ about 100 to lS00 pounds per square inch for about 2 to 10 minutes whereby to provide a cathodic solid polymer electrolyte surface. Thereafter an electrolytic cell may be assembled having coated tltanium anode bearing upon the anodic surface of the permionic membrane, and a nickel current collector bearing upon the cathodic, solid polymer electrolyte surface of the permionic membrane.
According to a still further exemplification of this invention, a permionic membrane electrolytic cell may be prepared having an anode bearing upon the surface of the permionic membrane and a multiple layer of silver oxide and platinum black deposit:ed on the cathodic surface of the permionic membrane. As herein contemplated, a sheet of perfluorocarbon copolymer having pendant carboxyllc acid ester groups may be coated with a suitable plasticizer as dioctylphthalate plasticizer to which 1 micron diameter silver oxide particles are applied. Thereafter, minus 325 mesh platinum black particles may be applied, and the resulting bilayer pressed at a temperature of about 180 to about 225C, and a pressure from about 800 to about 1500 pounds per square inch for about 2 to 10 minutes so as to obtain a solid polymer electrolyte cathodic surface having silver oxide particles in intimate contact with the permionic membrane and e~ternal particles of platinum blackO
_ 9 _ 7~
According to a still further exemplification of this invention, an ~ mil thick permionic membrane fabricated of a perfluorocarbon copolymer having pendant carboxylic acid ester groups may be coated with dodecyl-phthalate and minus 325 mesh copper particles. Thereafter the permionic membrane may be hot pressed at a temperature of abou~ 180C to 220 C and a pressure of about 700 to 1500 pounds per square inch for about 2 to about 10 mlnutes. The cathode may be a screen having abou~ 20 mesh per inch by 30 mesh per inch and a thickness of about 0.005 of an inch with an electro-deposited coating of platinum thereon. In this way there is provided a zero gap permionic membrane cell having copper particles as electrical distributors on the surface thereof.
The use of plasticizQrs, for example, phthalates, phosphates, and fatty acid esters is particularly advantageous in the method of this invention in order to enhance the adherence of the electronic current dlstribotor to the permionic membrane, e4pecially at reduced temperatures, presaures, and times of hot pressing.
The following examples are illustrative:
A permionic membrane electrolytic cell was assembled having a ruthenium dioxide coated anode bearing upon the anodic side of the permionic membrane, and platinum black and silver oxide, Ag2O, bonded to the cathodic side of the permionic membrane.
An eleven mil thick by 5 inch by 5 inch Asahi Glass Co., Ltd.
FLEMION~ HB permionic membrane fabricated of a perfluorocarbon copolymer having pendant carboxylic acid ester groups was coated with bis(2 ethyl hexyl) isophthalate plasticiæer to which was added 0.2 grams of minus 325 74~;2 mesh platinum black and 0.8 grams of minus 325 mesh silver oxide, A~2~, providing 3.4 milligrams per sguare centimeter of platinum and 12.8 grams per square centimeter of silver oxide. The coated permionic membr~ne was hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
Thereafter the electrolytic cell was assembled, with a ruthenium dioxide coated 40 mesh to the inch by 40 mesh to the inch, 3 inch by 3 inch~ titanium anode pressed against the anodic surface of the permionic membrane hy a 2.5 mesh to the inch by 5 mesh to the inch, 3 inch by 3 inch, ruthenium dioxide coated titanium screen. The cathode current collector was a 2.5 mesh to the inch by 5 mesh to the inch, 3 inch by 3 inch, nickel screen.
After 14 days of electrolysis the cell voltage was 3.36 volts at 400 Ampere3 per square foot with 86 percent cathode current efficiency.
EXAMPLE II
A permionic membrane electrolytic cell was assembled having a ruthenium dioxide coated titanium screen bearing upon the anodic surface of the permionic membrane and a bilayer of silver oxide, Ag20, and platinum black deposited on the cathode surface of the permionic membrane.
An eleven mil thick by 5 inch by 5 inch Asahi Glass Co., Ltd.
FLEMION~ HB permionic membrane formed of perfluorocarbo~ cop~lymer having pendant carboxylic acid ester groups was coated with bis(2 ethyl hexyl) isophthlate plasticizer. Silver oxide particles, 1 micron in diameter, were applied atop the plasticizer to provide a silver oxide loading oE 12 milligrams per ~quare centimeter. Atop the silver oxide, minus 325 mesh platinum black was applied to provide a platinum loading Gf 3.4 milligrams per square ~entimeter. The coated permionic membrane wss hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
~L8~
ThereaEter the electrolytic cell ~as as~embled, with a ruthenium dioxide coated, 40 mesh to the inch by 40 mesh to the inch, 3 inch by 3 inch ~itanium anode pressed ~gainst the anodic surface of the permionic membrane by a ruthenium dioxide coated, 2.5 mesh to the inch by 5 mesh to the inch, 3 inch by 3 inch titanium screen.
After 31 days of electrolysis the cell voltage ~as 3.56 volts at 396 Amperes per square foot and the cathode current efficiency was 87 percent.
EXAMPLE III
A permionic membrane electrolytic cell wa~ assembled having a ruthenium dioxide coated titanium anode screen bearing upon the anodic surface of the permionic membrane, and a platinum coated nickel cathode bearin~ upon the silver oxide coated, cathodic surface of the permionic membrane.
An 11 mil thick by 5 inch by 5 inch Asahi Gl~s~ Co., Ltd. FLEMION3 type HB permionic membrane fabricated of a perfluorocarbon copolymer having pendant carboxylic acid ester groups was coated with bis(2-ethyl hexyl) , o~
isophthlPte plasticizer. To this membrane was added 0.8 grsms of 1 micron silver oxide, Ag20. The membrane was then hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
The cathode was prepared by electrolytic&lly depositin~ platinum black onto a 40 mesh to the inch by 4~ mesh ~D the inch, 3 inch by 3 ineh, 0.005 ineh thiek expanded mesh niekel screen. The electrolytic cell was assembled ~ith a ruthenium dioxide coated, 40 me~h to the inch by the 40 mesh to the inch, 3 inch by 3 inch titanium screen anode bearing against the anodic surface of the permionic membr~ne, nd the platinum black coated nickel screen bearing against the silver oxide coated cathodic surfAce of the permionic membrane.
~8~
After 22 days of electroly~is the cell voltage was 3.41 volts at 396 Amperes per square foot, and the cathode current efficiency was 83.7 percent.
EXAMPLE IV
A ~ermionic membrane electrolyeic cell was assembled having a ruthenium dioxide coated titanium anode screen bearin8 against the anodic surface of the permionic membrane and a nickel screen cathode bearing against the silver oxide coated, cathodic surface of the permionic membrane.
An 11 mil thick hy 5 inch by 5 inch Asahi Glass Co., Ltd.
FLEMION~ type HB permionic me~brane fabricated of a ~erfluorocarbon copoly- -mer having pendant carboxylic acid eRter gro~ps was coated with bis(2-ethyl a, hexyl) isophthlate plasticizer. To this Membrane was added 0.8 grams of 1 micron silver oxide, Ag2O, powder. The membrane was then hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
The cathode was fln uncoated, 20 mesh to the inch by 30 mesh to the inch, 3 inch by 3 inch, 0.005 inch thick nickel screen. The electro-lytic cell was assembled with a ruthenium dioxide coated, 40 mesh to the inch, 3 inch by 3 inch, titanium screen anode against the anodic surface of the permionic membrane, and the nickel cathode pressed agninst the silver oxide coated, cathodic surface of the permionic membrane.
After 29 days of electrolysis the cell voltage ~as 3.31 volt~
at 396 Amperes per square foot, and the cathode current efficiency was 87.1 percent.
EXAMPLE V
A permionic membrane electrolytic cell was prepared by depositing cathodic electrocatalyst into the cathodic side of the permionic membrane by utilizing a plasticizer in conjunction wi~h the electrocatalyst prior to hot pressing the cathodic electrocatalyst into the permionic membrane.
An ll mil ~hick by 5 inch by 5 inch A~Phi Glass CompPny, Ltd.
FI.EMIO~ type ~ permionic membrane fabricated of a perfluorocarbon copoly-mer having pendant carboxylic acid ester groups was coated with bi~(2-ethyl hexyl) isopthalate plas~icizer. To the pla~tici~er coated surface of the permionic membrane was added 0.8 gram of minus 325 mesh platinum black.
The pla~inum black was added by air brushing.
l~ereafter the permionic mem~rane was hot pressed at 200 degrees Centigrade and 20 tons orce for 5 minutes. The cell was then assembled by pressing a ~0 mesh to the inch by 40 mesh to the inch, 3 inch by 3 inch, ruthenium dioxide coated titanium mesh screen against the anodic surface of the permionic membrane, and a 20 me~h to the inch by 30 mesh to the inch, 3 inch by 3 inch, cathode current collector against the platinum black coated, cathodic surface of the permionic membrane.
After 31 days of electrolysis the cell vol~age wa~ 3.86 volts at 396 Amperes per square foot, and the cathode current efficiency was 87.0 percent.
XA~PL~ VI
A permionic membrane electrolytic cell was prepared by depositing cathodic electrocatalyst into the cathodic surface of the permionic mem-brane utili~ing a plastici~er in conjunction ~ith particulate cathodic electrocataly~t.
A 5 mil thick by 3 inch by 3 inch Asahi Glass CGmpany Co., Ltd.
FLEMION~ type ~ permionic membrane fabricated of a perfluorocarbon copoly- -mer having pendant carbo~ylic acid ester groups was coated with bi~(2-ethyl hexyl) isophthlate plPsticizer. To the plasticizer coated surface of the permionic membrane was air brushed 0.4 gram~ of platinum black. The mem-brane wa8 then hot pressed at 200 degrees Centigrade and 20 eOns force for 5 minutes to adhere the catalyst to the membrane.
The cell was then assembled by pressing a 40 me~h to the inch by 40 mesh to the inch, 3 inch by 3 inch ruthenium dioxide coated titanium mesh screen againæt the anodic surface of èhe permionic membrane, and 20 mesh to the inch by 30 meæh to the inch, 3 inch by 3 inch cathode current collQctor against the platinum black coated, cathodic 3urface of the permionic membrane.
After 13 days of electrolyæi~ the cell voltage was 3.79 volts at 396 Amperæ per square foot, and ehe cathode current efficiency wa~
75.2 percent.
While the invention has been described with respect to certain preerred exemplifications and em~odimentsl the æcope of protection i~ not intended to be limited thereby, but only by the claima appended hereto.
Preferably, the elec~ricslly conductive, Rub~tantially non-catslytic material i~ chosen Erom the group con3isting of Group IB metals ant corrosion re6i~ant, electrically conductive, but ~ub~tantially non-electrocatalytic compounds thereof. These ~sterials include copper, silv~r, and gold, as well as those oxides thereof that are seable in the aqueous, slkali ~e~al hydroxide envison~ent. Especially preferred, for reu~ons of co~t, availabili~y, and lo~ electrocatalytic ac~iviey, are silver oxide, silver, and copper.
- 2a The electrically conductive~ substantially non-electrocatalytic material may be a particulate material, for example, particles having a particle size of ~rom about 0.1 micron ~o about minus 2~0 me~h and prefera-bly from about 0.5 micron to about minus 325 mesh. The substantially non-electrocatalytic, electrically conductive material is preferably adherent to the permionic membrane. That i8, it i6 preferably bondsd to and embedded in the permionic membrane, and substantially non-removable therefrom with-out degradation, partial destruction, or de~truction of either the material or the permionic membrane, or both. Alternatively, especially when the non-catalytic material is of a finer mesh si~e than the electrocatalyst, it may be adherent to either the electrocatalyst or to the substrate carrying the electrocataLyst, as where the electrocatalyst i8 a particulate electro-catalyst bonded to a metallic substrate, with particulate conductor material on the substrate, and between and on the e'Lectrocatalyst particles.
Typicfllly, the cathode electrocal:alyst of the electrolytic cell is a Group VIII transition metal, having a lower hydrogen evolution over-voltage than ~he electrically conductive, l3ubstsntially non-electrocatalytic material. Typical cathodic electrocatalysts include iron, cobalt, nickel and the platinum group metals, especially electrocPlly catalytic forms such as Raney nickel, platini~ed platinum, and platinum black.
According to an alternative exemplification of the method of this invention, there i8 provided a method of electrolyzing an alkali metal chloride brine in an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with a cathode therein, and a permionic mambrane therebetween. The cathode contacts the permionic membrane, preferably and removably, that is readily removable without destruction or degradation of either the cathodlc electrocatalyst or the 7~2 permionic membrane. As herein contempla~e~, the process comprises passing an electrical current from the anode to the cathode, whereby to evolve chlorine at the anode and hydroxyl ion at the cathode. The method is characteri~ed in that the permionic membrane has on its cathodic aurface electrically conductive, sub~tantially non-electrocatalytic material either adherent thereto or in contac therewith J as descrihed ~bove.
Accordin~ to one exemplification herein contemplated, the current distributor may be bonded to the cathodic surface of the permionic membrane alone, that i8, without electrocatalyst being present thereon. In this way, the electrocatalyst is readily removable from the surface, and i9 present on a separate electrode structure, i.e., a metallic screen, mesh, shee, plate, or the like, having a coating, surface, or film of electrocatalyst n~ herein described.
According to an alternative exemplification, the electrocatalyst i~ present as a bilayer, i.e., a~ a second layer, atop the layer, sur- -face, or film of particulate, electrically conductive, substantially non-electrocatalytic ~aterial which is bonded to and embedded in the permionic mernbrane. According to this exemplification, the ~ubstantially non-electrocatalytic, electrically conductive material is applied first to the permionic membrane, and thereafter the electrocatalyst i8 applied thereto, both above and between particles of ~he conductive, non-catalytic material.
According to a 3ill further exemplification of the method of this invention, electrocatalyst may be present on the ~urface of the per-mionic membrane, in admi~ture with the electrically conducti~e, substan-tially non-catalytic material wnich i5 also adherent to the permionic membrane surface.
According to a still further exemplification, the electrocatalyst and the non-catalytic material may bo~h be present on and adherent to an electroconductive subetrate, and removable from the permionic membrane.
Generally the loading of the electronically conductive, current distributor i6 from about 1 milligram per square centimeter to about 100 milligrams per square, and generally from about 2 to about 20 milligrams per square centimeter. Amounts lower than about 1 milligram per gquare centimeter do not provide significant amount~ of current distribution, ~hile amounts greater than about 100 milligrams per square centimeter may ~uhstantially interfere with the electrochemical process, providing an impermeable barrier, sheet, or film on the cathodic surface of the permi-onic membrane.
The permionic membrane interposed between the-anolyte and the porou~ matrix is fabricated of a polymeric fluorocarbon copolymer having immobile, cation selective ion exchange group~ on a halocarbon backbone.
The membrane may b~ from about 2 to about ~S mils thick, although thicker or thinner permionic membranes may be utilized. The permionic membrane may be a laminate of two or more membrane ~heet~. It may, additionally, have internal reinforcing fibers.
The permionic membrane may be a copolymer of (I) a fluorovinyl polyether having pendant ion exchange groups and having the formula (I) CF2~CF-Oa-[(CX'X'')C (CFX')d (CF2-0-(XIX")e (CX"X'0-CF2)~-A
w~ere a is 0 or 1, b i8 0 to 6, c iB 0 to 6, d is 0 to 6, e i8 0 to 6, f i8 0 to 6; X, X', and X" are ~ Cl, -F, and -(CF2)gCF3; g i8 1 to 5, [ ] i8 a discretionary arrangement of the moieties therein; and A is the pendant functional group as will be described hereinbelow. Preferably a i8 1, and X, X' ~nd X" are -F and (CF2)gCF3.
7~
The fluorovinyl polyether may be copolymerized with a (II) fluoro-vinyl compound (II) CF2 = CF~a~(CF~ d) A
and a (III) perfluorinated olefin (III) CF2 - CXX', or (I) may be copolymerized with only a (III~ perfluorinated olefin, or (I) may be copolymerized with only a (II) perfluorovinyl compound.
The functional group is a cation selective group. It may be a sulfonic group, a phosphoric group, a phosphonic group, a carboxylic group, ~ a precursor thereof, or a reaction product thereof, e.g., an ester thereof.
Carboxylic groups, precursor~ thereof, and reactions products thereof are preferred. Thus, as herein contemplated, A is preferably chosen from the group consisting of -COOH, -COOR l, -COOM, -GOF, -COCl, -CN, -CONR2R3 ~
-S03H, -S03M, -S02F, and -S02Cl where Rl is a Cl to Clo alkyl group, R2 and R3 are hydrogen or Cl to Clo alkyl groups, and M i~ an alkali metal or a quaternary ammonium group.
According to a particularly preerrPd exemplification, A is ~7fl~
-COCl, -COO~I, -COORl, -S02F, or -S02Cl where Rl i8 a Cl to Cs alkyl.
As herein contemplated, the permionic membrane i~ preferably a copolymer which may have:
~I) fluorovinyl ether acid moieties derived from CF2=cF-o-lcF2btcxlx~)ctcFx~)tcF2-o-cx~x~i)etcx~x~-o~cF2)f~-A~ -exemplified by CF2=CFOCF2CFtCF30CF3CF2CF2COOOCH3, CF2=CFO(CF2)30CFCOOCH3, CF2=CFotCF2)40CIFCoc~cH3, CF2=CFOCF2CFCF2COOCH3, and CF2=CFOCF2CF(CF3)0CF(COOC~3)CF3, inter alia;
(II) fluorovinyl moieties derived from CF2~CF-to)~,-(CFX' )d-A, exemplified by CF2-CF(CF2)2_4COOCH3 CF2-CF ( CF2 ) 2-4COOCH3 ~
CF~=CFotCF2)2_4CooCH3, CF2 = CFotCF2)2_4CooC2H5~ and CF2 = CFO(CF2)2-4CoOcH3, inter alia;
7~L;~
(III) fluorinated olefin moieties derived from CF = CXX' as exenplified by tetrafluoroethylene, trichlorofluoroethylene, hexafluoropropylene, trifluoroethylene, vinylidene, fluorlde, and the like; and (IV) vinyl ethers derived from CF2 = CFOR4 The permionic membrane herein contemplated has an ion exchange capacity of from about 0.5 to about 2.0 milliequivalentspergram of dry polymer, preferably from about 0.9 to about 1.8 milliequivalents per gram of dry polymer, and in a particularly preferred exemplification, from about 1.0 to about 1.6 milliequivalents per gram of dry polymer. The permionic membrane herein contemplated has a volumetric flow rate of 100 cubic millimeters per second at a temperature of 150 to 300 degrees Centlgrade, and preferably at a temperature between 160 to 250 degrees Centigrade. The glass transition temperature of the permionic membrane polymer is below 70C, and preferably below about 50C.
The permionic membrane herein contemplated may be prepared by the methods described in U.S. Patent 4,126,588.
Most commonly the ion exchange resins will be in a thermoplastic form, i.e., a carboxylic acid ester, e.g., a carboxylic acid ester of methyl, ethyl, propyl, isopropyl, or butyl alcohol, or a sulfonyl halide, e.g., sulfonyl chloride or sulfonyl fluoride, during the fabrication herein contemplated9 and will thereafter be hydrolyzed.
According to one exemplification of this invention, an electro-lytic cell may be assembled having an anode bearing upon the anodic surface of the permionic membrane, and platinum black and silver oxide, Ag2O bonded to the cathodic side of the permionlc membrane. According to this exempliEicatlon, a perfluorocarbon polymer having pendant carboxylic acid ester groups, l.e.~ being in the thermoplastic form, may be coated with a plasticizer, i.e., bis(2-ethyl hexyl) isophthalate, one part platinum black and 4 parts silver oxide, whereby to provide a loading of about 12 milligrams per square centimeter of silver oxide and about 3 milligrams per square centimeter of platinum black. The coated permionic membrane may ~hen be hot pressed, for example from about 180C to about 225C and at a pressure o~ about 100 to lS00 pounds per square inch for about 2 to 10 minutes whereby to provide a cathodic solid polymer electrolyte surface. Thereafter an electrolytic cell may be assembled having coated tltanium anode bearing upon the anodic surface of the permionic membrane, and a nickel current collector bearing upon the cathodic, solid polymer electrolyte surface of the permionic membrane.
According to a still further exemplification of this invention, a permionic membrane electrolytic cell may be prepared having an anode bearing upon the surface of the permionic membrane and a multiple layer of silver oxide and platinum black deposit:ed on the cathodic surface of the permionic membrane. As herein contemplated, a sheet of perfluorocarbon copolymer having pendant carboxyllc acid ester groups may be coated with a suitable plasticizer as dioctylphthalate plasticizer to which 1 micron diameter silver oxide particles are applied. Thereafter, minus 325 mesh platinum black particles may be applied, and the resulting bilayer pressed at a temperature of about 180 to about 225C, and a pressure from about 800 to about 1500 pounds per square inch for about 2 to 10 minutes so as to obtain a solid polymer electrolyte cathodic surface having silver oxide particles in intimate contact with the permionic membrane and e~ternal particles of platinum blackO
_ 9 _ 7~
According to a still further exemplification of this invention, an ~ mil thick permionic membrane fabricated of a perfluorocarbon copolymer having pendant carboxylic acid ester groups may be coated with dodecyl-phthalate and minus 325 mesh copper particles. Thereafter the permionic membrane may be hot pressed at a temperature of abou~ 180C to 220 C and a pressure of about 700 to 1500 pounds per square inch for about 2 to about 10 mlnutes. The cathode may be a screen having abou~ 20 mesh per inch by 30 mesh per inch and a thickness of about 0.005 of an inch with an electro-deposited coating of platinum thereon. In this way there is provided a zero gap permionic membrane cell having copper particles as electrical distributors on the surface thereof.
The use of plasticizQrs, for example, phthalates, phosphates, and fatty acid esters is particularly advantageous in the method of this invention in order to enhance the adherence of the electronic current dlstribotor to the permionic membrane, e4pecially at reduced temperatures, presaures, and times of hot pressing.
The following examples are illustrative:
A permionic membrane electrolytic cell was assembled having a ruthenium dioxide coated anode bearing upon the anodic side of the permionic membrane, and platinum black and silver oxide, Ag2O, bonded to the cathodic side of the permionic membrane.
An eleven mil thick by 5 inch by 5 inch Asahi Glass Co., Ltd.
FLEMION~ HB permionic membrane fabricated of a perfluorocarbon copolymer having pendant carboxylic acid ester groups was coated with bis(2 ethyl hexyl) isophthalate plasticiæer to which was added 0.2 grams of minus 325 74~;2 mesh platinum black and 0.8 grams of minus 325 mesh silver oxide, A~2~, providing 3.4 milligrams per sguare centimeter of platinum and 12.8 grams per square centimeter of silver oxide. The coated permionic membr~ne was hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
Thereafter the electrolytic cell was assembled, with a ruthenium dioxide coated 40 mesh to the inch by 40 mesh to the inch, 3 inch by 3 inch~ titanium anode pressed against the anodic surface of the permionic membrane hy a 2.5 mesh to the inch by 5 mesh to the inch, 3 inch by 3 inch, ruthenium dioxide coated titanium screen. The cathode current collector was a 2.5 mesh to the inch by 5 mesh to the inch, 3 inch by 3 inch, nickel screen.
After 14 days of electrolysis the cell voltage was 3.36 volts at 400 Ampere3 per square foot with 86 percent cathode current efficiency.
EXAMPLE II
A permionic membrane electrolytic cell was assembled having a ruthenium dioxide coated titanium screen bearing upon the anodic surface of the permionic membrane and a bilayer of silver oxide, Ag20, and platinum black deposited on the cathode surface of the permionic membrane.
An eleven mil thick by 5 inch by 5 inch Asahi Glass Co., Ltd.
FLEMION~ HB permionic membrane formed of perfluorocarbo~ cop~lymer having pendant carboxylic acid ester groups was coated with bis(2 ethyl hexyl) isophthlate plasticizer. Silver oxide particles, 1 micron in diameter, were applied atop the plasticizer to provide a silver oxide loading oE 12 milligrams per ~quare centimeter. Atop the silver oxide, minus 325 mesh platinum black was applied to provide a platinum loading Gf 3.4 milligrams per square ~entimeter. The coated permionic membrane wss hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
~L8~
ThereaEter the electrolytic cell ~as as~embled, with a ruthenium dioxide coated, 40 mesh to the inch by 40 mesh to the inch, 3 inch by 3 inch ~itanium anode pressed ~gainst the anodic surface of the permionic membrane by a ruthenium dioxide coated, 2.5 mesh to the inch by 5 mesh to the inch, 3 inch by 3 inch titanium screen.
After 31 days of electrolysis the cell voltage ~as 3.56 volts at 396 Amperes per square foot and the cathode current efficiency was 87 percent.
EXAMPLE III
A permionic membrane electrolytic cell wa~ assembled having a ruthenium dioxide coated titanium anode screen bearing upon the anodic surface of the permionic membrane, and a platinum coated nickel cathode bearin~ upon the silver oxide coated, cathodic surface of the permionic membrane.
An 11 mil thick by 5 inch by 5 inch Asahi Gl~s~ Co., Ltd. FLEMION3 type HB permionic membrane fabricated of a perfluorocarbon copolymer having pendant carboxylic acid ester groups was coated with bis(2-ethyl hexyl) , o~
isophthlPte plasticizer. To this membrane was added 0.8 grsms of 1 micron silver oxide, Ag20. The membrane was then hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
The cathode was prepared by electrolytic&lly depositin~ platinum black onto a 40 mesh to the inch by 4~ mesh ~D the inch, 3 inch by 3 ineh, 0.005 ineh thiek expanded mesh niekel screen. The electrolytic cell was assembled ~ith a ruthenium dioxide coated, 40 me~h to the inch by the 40 mesh to the inch, 3 inch by 3 inch titanium screen anode bearing against the anodic surface of the permionic membr~ne, nd the platinum black coated nickel screen bearing against the silver oxide coated cathodic surfAce of the permionic membrane.
~8~
After 22 days of electroly~is the cell voltage was 3.41 volts at 396 Amperes per square foot, and the cathode current efficiency was 83.7 percent.
EXAMPLE IV
A ~ermionic membrane electrolyeic cell was assembled having a ruthenium dioxide coated titanium anode screen bearin8 against the anodic surface of the permionic membrane and a nickel screen cathode bearing against the silver oxide coated, cathodic surface of the permionic membrane.
An 11 mil thick hy 5 inch by 5 inch Asahi Glass Co., Ltd.
FLEMION~ type HB permionic me~brane fabricated of a ~erfluorocarbon copoly- -mer having pendant carboxylic acid eRter gro~ps was coated with bis(2-ethyl a, hexyl) isophthlate plasticizer. To this Membrane was added 0.8 grams of 1 micron silver oxide, Ag2O, powder. The membrane was then hot pressed at 200 degrees Centigrade and 20 tons force for 5 minutes.
The cathode was fln uncoated, 20 mesh to the inch by 30 mesh to the inch, 3 inch by 3 inch, 0.005 inch thick nickel screen. The electro-lytic cell was assembled with a ruthenium dioxide coated, 40 mesh to the inch, 3 inch by 3 inch, titanium screen anode against the anodic surface of the permionic membrane, and the nickel cathode pressed agninst the silver oxide coated, cathodic surface of the permionic membrane.
After 29 days of electrolysis the cell voltage ~as 3.31 volt~
at 396 Amperes per square foot, and the cathode current efficiency was 87.1 percent.
EXAMPLE V
A permionic membrane electrolytic cell was prepared by depositing cathodic electrocatalyst into the cathodic side of the permionic membrane by utilizing a plasticizer in conjunction wi~h the electrocatalyst prior to hot pressing the cathodic electrocatalyst into the permionic membrane.
An ll mil ~hick by 5 inch by 5 inch A~Phi Glass CompPny, Ltd.
FI.EMIO~ type ~ permionic membrane fabricated of a perfluorocarbon copoly-mer having pendant carboxylic acid ester groups was coated with bi~(2-ethyl hexyl) isopthalate plas~icizer. To the pla~tici~er coated surface of the permionic membrane was added 0.8 gram of minus 325 mesh platinum black.
The pla~inum black was added by air brushing.
l~ereafter the permionic mem~rane was hot pressed at 200 degrees Centigrade and 20 tons orce for 5 minutes. The cell was then assembled by pressing a ~0 mesh to the inch by 40 mesh to the inch, 3 inch by 3 inch, ruthenium dioxide coated titanium mesh screen against the anodic surface of the permionic membrane, and a 20 me~h to the inch by 30 mesh to the inch, 3 inch by 3 inch, cathode current collector against the platinum black coated, cathodic surface of the permionic membrane.
After 31 days of electrolysis the cell vol~age wa~ 3.86 volts at 396 Amperes per square foot, and the cathode current efficiency was 87.0 percent.
XA~PL~ VI
A permionic membrane electrolytic cell was prepared by depositing cathodic electrocatalyst into the cathodic surface of the permionic mem-brane utili~ing a plastici~er in conjunction ~ith particulate cathodic electrocataly~t.
A 5 mil thick by 3 inch by 3 inch Asahi Glass CGmpany Co., Ltd.
FLEMION~ type ~ permionic membrane fabricated of a perfluorocarbon copoly- -mer having pendant carbo~ylic acid ester groups was coated with bi~(2-ethyl hexyl) isophthlate plPsticizer. To the plasticizer coated surface of the permionic membrane was air brushed 0.4 gram~ of platinum black. The mem-brane wa8 then hot pressed at 200 degrees Centigrade and 20 eOns force for 5 minutes to adhere the catalyst to the membrane.
The cell was then assembled by pressing a 40 me~h to the inch by 40 mesh to the inch, 3 inch by 3 inch ruthenium dioxide coated titanium mesh screen againæt the anodic surface of èhe permionic membrane, and 20 mesh to the inch by 30 meæh to the inch, 3 inch by 3 inch cathode current collQctor against the platinum black coated, cathodic 3urface of the permionic membrane.
After 13 days of electrolyæi~ the cell voltage was 3.79 volts at 396 Amperæ per square foot, and ehe cathode current efficiency wa~
75.2 percent.
While the invention has been described with respect to certain preerred exemplifications and em~odimentsl the æcope of protection i~ not intended to be limited thereby, but only by the claima appended hereto.
Claims (6)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method of electrolyzing an alkali metal chloride brine in an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with a cathode therein, and a permionic membrane therebetween, said cathode contacting the permionic membrane, which method comprises passing an electrical current from the anode to the cathode, evolving chlorine at the anode and hydroxyl ion at the cathode; the improvement wherein said cathode comprises a Group VIII transition metal as electrocatalyst, said permionic membrane has an anodic surface and a cathodic surface, the cathodic surface thereof having electrically conductive, substantially non-electrocatalytic particles of material chosen from the group consisting of Group IB metals and corrosion resistant, electrically conductive compounds thereof bonded thereto, the particles having a hydrogen evolution overvoltage at least 0.1 volt higher than the hydrogen overvoltage of the electrocatalyst cathode.
2. The method of claim 1 wherein the electrically conductive, non-catalytic material and the electrocatalyst are bonded to the permionic membrane.
3. The method of Claim 1 wherein the electrically conductive, non-catalytic material is bonded to the permionic membrane, and the electrocatalyst compressively and removably bears on the permionic membrane,
4. In an electrolytic cell having an anolyte compartment with an anode therein, a catholyte compartment with a cathode therein, and a permionic membrane therebetween, said cathode contacting the permionic membrane, the improvement wherein said cathode comprises a Group VIII
transition metal as the electrocatalyst, and the cathodic surface of the permionic membrane has electrically conductive, substantially non-electro-catalytic particles of a material chosen from the group consisting of Group IB metals and corrosion resistant, electrically conductive compounds thereof bonded thereto, the particles having a hydrogen overvoltage at least 0.1 volt higher than the hydrogen overvoltage of the electrocatalyst.
transition metal as the electrocatalyst, and the cathodic surface of the permionic membrane has electrically conductive, substantially non-electro-catalytic particles of a material chosen from the group consisting of Group IB metals and corrosion resistant, electrically conductive compounds thereof bonded thereto, the particles having a hydrogen overvoltage at least 0.1 volt higher than the hydrogen overvoltage of the electrocatalyst.
5. The electrolytic cell of claim 4 wherein the electrically conductive, non-catalytic material and the electrocatalyst are bonded to the permionic membrane.
6. The electrolytic cell of Claim 4 wherein the electrically conductive, non-catalytic material is bonded to the permionic membrane, and the electrocatalyst compressively and removably bears on the permionic membrane.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US20758080A | 1980-11-17 | 1980-11-17 | |
| US207,580 | 1980-11-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1187442A true CA1187442A (en) | 1985-05-21 |
Family
ID=22771167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000388583A Expired CA1187442A (en) | 1980-11-17 | 1981-10-23 | Permionic membrane electrolytic cell current distribution means |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS57114674A (en) |
| KR (1) | KR890000626B1 (en) |
| AU (1) | AU529875B2 (en) |
| BE (1) | BE891133A (en) |
| CA (1) | CA1187442A (en) |
| DE (1) | DE3145324C2 (en) |
| ES (2) | ES8300145A1 (en) |
| FR (1) | FR2494305B1 (en) |
| GB (1) | GB2087433B (en) |
| IT (1) | IT1144932B (en) |
| NL (1) | NL8104559A (en) |
| NO (1) | NO813552L (en) |
| SE (1) | SE443582B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4832805A (en) * | 1981-12-30 | 1989-05-23 | General Electric Company | Multi-layer structure for electrode membrane-assembly and electrolysis process using same |
| IT1197007B (en) * | 1986-07-28 | 1988-11-25 | Oronzio De Nora Impianti | CATHOD GLUED TO THE SURFACE OF AN ION EXCHANGE MEMBRANE, FOR USE IN AN ELECTROLYZER FOR ELECTROCHEMICAL PROCESSES AND RELATED METHOD OF ELECTROLYSIS |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1118243B (en) * | 1978-07-27 | 1986-02-24 | Elche Ltd | MONOPOLAR ELECTROLYSIS CELL |
-
1981
- 1981-10-07 SE SE8105932A patent/SE443582B/en not_active IP Right Cessation
- 1981-10-07 NL NL8104559A patent/NL8104559A/en not_active Application Discontinuation
- 1981-10-15 AU AU76376/81A patent/AU529875B2/en not_active Ceased
- 1981-10-21 NO NO813552A patent/NO813552L/en unknown
- 1981-10-23 CA CA000388583A patent/CA1187442A/en not_active Expired
- 1981-10-23 FR FR8119992A patent/FR2494305B1/en not_active Expired
- 1981-10-26 ES ES506561A patent/ES8300145A1/en not_active Expired
- 1981-10-26 ES ES506560A patent/ES8206666A1/en not_active Expired
- 1981-11-11 KR KR8104327A patent/KR890000626B1/en active
- 1981-11-13 GB GB8134239A patent/GB2087433B/en not_active Expired
- 1981-11-14 DE DE3145324A patent/DE3145324C2/en not_active Expired
- 1981-11-16 BE BE0/206552A patent/BE891133A/en not_active IP Right Cessation
- 1981-11-17 IT IT25134/81A patent/IT1144932B/en active
- 1981-11-17 JP JP56184326A patent/JPS57114674A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| KR890000626B1 (en) | 1989-03-22 |
| IT1144932B (en) | 1986-10-29 |
| ES506560A0 (en) | 1982-08-16 |
| GB2087433B (en) | 1984-02-22 |
| NL8104559A (en) | 1982-06-16 |
| FR2494305A1 (en) | 1982-05-21 |
| KR830007880A (en) | 1983-11-07 |
| ES8206666A1 (en) | 1982-08-16 |
| BE891133A (en) | 1982-05-17 |
| ES506561A0 (en) | 1982-10-01 |
| IT8125134A0 (en) | 1981-11-17 |
| JPS57114674A (en) | 1982-07-16 |
| DE3145324A1 (en) | 1982-06-03 |
| DE3145324C2 (en) | 1987-01-02 |
| NO813552L (en) | 1982-05-18 |
| FR2494305B1 (en) | 1986-02-28 |
| AU529875B2 (en) | 1983-06-23 |
| ES8300145A1 (en) | 1982-10-01 |
| SE8105932L (en) | 1982-05-18 |
| GB2087433A (en) | 1982-05-26 |
| SE443582B (en) | 1986-03-03 |
| AU7637681A (en) | 1982-07-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4389297A (en) | Permionic membrane electrolytic cell | |
| CA1280716C (en) | Ion exchange membrane with non-electrode layer for electrolytic processes | |
| US4293394A (en) | Electrolytically producing chlorine using a solid polymer electrolyte-cathode unit | |
| CA1173105A (en) | Solid polymer electrolytes and electrode bonded with hydrophyllic fluorocopolymers | |
| US4299675A (en) | Process for electrolyzing an alkali metal halide | |
| US4315805A (en) | Solid polymer electrolyte chlor-alkali process | |
| US5168005A (en) | Multiaxially reinforced membrane | |
| EP0226911B1 (en) | An improved solid polymer electrolyte electrode | |
| GB2069006A (en) | Solid Polymer Electrolyte, Method of Preparing Same and Chlor-alkali Electrolytic Cells Containing Same | |
| EP0045603A1 (en) | Ion exchange membrane cell and electrolytic process using the same | |
| EP0090381B1 (en) | Electrode and method of electrolysis | |
| US4364815A (en) | Solid polymer electrolyte chlor-alkali process and electrolytic cell | |
| US4411749A (en) | Process for electrolyzing aqueous solution of alkali metal chloride | |
| EP0192261B1 (en) | Multilayer cation exchange membrane | |
| US4749452A (en) | Multi-layer electrode membrane-assembly and electrolysis process using same | |
| EP0094587B2 (en) | Improved electrolytic cation exchange membrane | |
| US4369103A (en) | Solid polymer electrolyte cell | |
| US4364813A (en) | Solid polymer electrolyte cell and electrode for same | |
| EP0753534A2 (en) | Cation exchange membrane for electrolysis and process for producing potassium hydroxide of high purity | |
| CA1293952C (en) | Method for forming a solid polymer electrolyte structure by pressing catalyst into membrane | |
| EP0064389A1 (en) | Composite membrane/electrode, electrochemical cell and electrolysis process | |
| CA1187442A (en) | Permionic membrane electrolytic cell current distribution means | |
| CA1206439A (en) | Ion exchange membrane of fluorinated polymer with porous non-electrode layer | |
| US4356068A (en) | Permionic membrane | |
| US4361601A (en) | Method of forming a permionic membrane |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |