US3632444A - Graphite anode treatment - Google Patents

Graphite anode treatment Download PDF

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Publication number
US3632444A
US3632444A US789007A US3632444DA US3632444A US 3632444 A US3632444 A US 3632444A US 789007 A US789007 A US 789007A US 3632444D A US3632444D A US 3632444DA US 3632444 A US3632444 A US 3632444A
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United States
Prior art keywords
graphite
iron
percent
electrode
impregnated
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Expired - Lifetime
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US789007A
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English (en)
Inventor
Morris P Grotheer
John A Peterson
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Occidental Chemical Corp
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Hooker Chemical Corp
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Assigned to OCCIDENTAL CHEMICAL CORPORATION reassignment OCCIDENTAL CHEMICAL CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE APRIL 1, 1982. Assignors: HOOKER CHEMICALS & PLASTICS CORP.
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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
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/042—Electrodes formed of a single material
    • C25B11/043—Carbon, e.g. diamond or graphene
    • C25B11/044—Impregnation of carbon

Definitions

  • An iron impregnated graphite electrode is prepared by treating graphite with a liquid metal such as iron or a mixture of iron with carbon and/or silicon.
  • GRAPHITE ANODE TREATMENT BACKGROUND OF THE INVENTION Graphite anodes have been conventionally employed in electrolytic processes for the electrolysis of aqueous solutions of alkali metal halides, both in the production of halogens and caustic as well as alkali metal halates.
  • the cost of graphite is a large factor in the overall price of electrolytic cell products.
  • Graphite presents a relatively larger cost factor in chlorate production than in chlor-alkali production.
  • the electrode graphite is impregnated with a drying oil which tends to prevent wetting on the interior of the graphite by an aqueous electrolyte.
  • an electrode material comprising a massive graphite structure impregnated with iron exhibited excellent structural and electrical properties.
  • the electrodes contain by weight, based upon the final product, between 0.05-3, percent iron, and preferably, 0.052.5 percent iron in the graphite matrix. More than 3 percent iron does not appear to provide any advantage.
  • a method for preparing iron impregnated graphite which comprises contacting a massive graphite structure with a liquid metal selected form the group consisting of iron and iron mixed with at least one member selected from the group consisting of carbon and silicon, separating said massive graphite structure from said liquid metal and cooling said massive graphite in a substantially inert atmosphere.
  • the graphite which is employed in the instant invention may be porous fuel cell grade graphite or standard anode grade graphite.
  • Exemplary of the graphite matrixes under consideration are porous graphite having an apparent density of 0.936 and approximately 58.4 percent voids by volume; porous graphite of apparent density 1.04 having approximately 53.8 percent voids by volume and anode grade graphite of apparent density 1.67 having approximately 25.6 percent voids by volume. These calculated voids are based upon a standard theoretical specific gravity for graphite of 2.25.
  • the preferred graphite for the electrolytic purposes of this invention is preferably that of apparent density between 1.40 and 1.80.
  • Iron and iron alloys of carbon and silicon may be employed in the practice of the instant invention.
  • Acceptable alloys of iron which do not otherwise interfere in the use of iron impregnated graphite as an electrode in chlor-alkali and chlorate production include those Fe-C alloys approximately in the range of 94-999 Fe and 0.1-6 C; while the applicable silicon containing alloys include those with a silicon content as high as percent by weight.
  • grey cast iron contains 94 Fe, 3.5 C, 2.5 Si while the high silicon content cast irons contain approximately 84.3 Fe, 14.5 Si, 0.85 C and trace amounts of Mn, P and S.
  • the amount of iron deposited within the pores of a graphite electrode matrix may be controlled by limiting the exposure time to the liquid metal.
  • the graphite surface is rapidly wet with metal which will continue to penetrate into the internal region of the graphite after withdrawal from the molten bath.
  • the molten iron may be efficiently prepared either by melting iron or an iron alloy through application of heat or by chemical reaction such as may be exemplified by the process 8 Al 3 Fe O 9Fe (molten) 4Al O
  • the graphite structure to be treated may be placed in a crucible and covered by the reactants.
  • a pool of molten iron forms at the bottom of the crucible and surrounds the graphite structure effectively penetrating into the pores of the graphite. Removal of the graphite structure while the iron is still in liquid state affords an acceptably impregnated graphite structure.
  • the process of this invention avoids the-multistep technique presented in copending Application Ser. No. 2251 referred to supra, and provides a direct approach, adaptable to commercial graphite production techniques, for iron impregnation of graphite.
  • the resulting iron impregnated graphite may be optionally post impregnated with a conventional drying oil such as linseed oil, or it may be used directly as an anode material. It is preferred to seal the iron impregnated graphite with oil to prevent excessive attack by the corrosive contents of the electrolytic cell.
  • EXAMPLE 1 A block of graphite, lXl'X'r inches was packed in a mixture of iron filings and carbon powder in a fire clay crucible. The mixture was 94 percent by weight iron and 6 percent by weight carbon. The crucible and contents were heated at a temperature between 1,000 to about 1,400 C. over a period of 4 hours and then maintained at 1,400 C. for 1% hours. The crucible was removed from the furnace and molten metal phase was poured out. The graphite block was recovered and allowed to cool in an inert nitrogenous atmosphere. When cool, some large metallic beads were removed from the graphite surface by gentle scraping. The product was dark gray in color and exhibited some pitting. Under 10 power magnification, very small metallic beads were observed on the graphite surface.
  • the resulting graphite block was exposed as an anode to a solution containing about 300 grams per liter sodium chloride.
  • the electrode chlorine overvoltage was 1.27 volts at one ampere per square inch whereas the chlorine overvoltage for conventional chlor-alkali grade, oil impregnated graphite exhibits approximately 1.35 volts at l ampere per square inch.
  • a graphite electrode is manufactured by preparation weighing, and mixing of the raw materials; (normally high purity extrusion carbon and a binder such as coal tar pitch) of the heated mixture in the desired shape and cross section; baking in a gas-fired furnace and graphitization in a continuous tube electric furnace.
  • the electric furnace is operated at a temperature sufficient to produce a graphitization temperature of bout 2,800 C.
  • the graphite electrodes are quenched in a bath of molten iron which is maintained at a temperature of about 1,400 C.
  • An intermediate cooling step to prevent fracturing of the graphite may be employed if necessary.
  • the graphite is impregnated with iron from the molten bath, withdrawn and cooled slowly to room temperature.
  • An inert atmosphere is provided for the graphite as it cools to about 500 C., either in the form of an inert gas such as CO, argon or nitrogen, or via surface oxidation of the graphite in a limited atmosphere (withthe production of CO).
  • an inert gas such as CO, argon or nitrogen
  • Elemental analysis of an iron impregnated electrode prepared in a manner similar to the procedure of example 2 demonstrated that 0.15 percent iron was present in the graphite structure. lmpregnation was evidenced throughout the sample.
  • Teflon cloth diaphragm separated the anolyte from catholyte.
  • the electrolyte was 295 grams per liter sodium chloride at C.
  • An Anotrol Model 4100 potentiostat in conjunction with a Houston X-Y recorder was used to obtain the anodic polarization.
  • the iron impregnated graphite electrode prepared in accordance with the instant invention demonstrated an anode potential with reference to a saturated calomel electrode about 0.1 volt below that of a conventional graphite electrode at l ampere per square inch.
  • the electrode prepared by the process of this invention exhibits reduced chlorine overvoltage in comparison to conventional chlor-alkali and chlorate grade graphite electrodes when employed in chlor-alkali and chlorate production. Furthermore, the electrode of this case is considerably less prone to consumption in chlorate production than in a conventional chlorate grade graphite anode.
  • the increase in cell voltage with decrease in NaCl concentration is considerably less with the iron impregnated graphite electrode prepared in accordance with the procedures of this invention than it is with a conventionally oil treated graphite electrode.
  • the concentration of NaCl decreased from about 250 grams per liter to about 150 grams per liter
  • the cell voltage increased from about 3.25 volts to 3.6 volts with the normal graphite while with iron impregnated graphite
  • the increase in cell voltage was from about 3.15 to 3.35 volts.
  • the iron deposits in the iron impregnated graphite of this invention is singularly found in the pores of the graphite matrix, it is applicants desire not to be bound by that theory because a portion of the iron may actually be in an intercalated state. Hence, it is desired to cover the invention in any of its operative forms as iron impregnated graphite whether that iron appears in intercalated form or as heterogeneous deposits within the pores of the graphite matrix.
  • a process for the production of an iron impregnated graphite electrode which comprises heating a formed carbonaceous material to produce graphite having an apparent density of between 1.40 and 1.80 and quenching said graphite in a liquid metal selected from the group consisting of iron, an iron carbon mixture containing about 0.1 to 6 percent carbon by weight, and an iron silicon mixture containing below about 15 percent silicon by weight.
  • liquid metal is an iron-carbon mixture containing from about 0.1 to 6 percent carbon by weight.
  • liquid metal is an iron-carbon mixture containing between 3 to 4 percent carbon by weight.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Carbon And Carbon Compounds (AREA)
US789007A 1968-12-31 1968-12-31 Graphite anode treatment Expired - Lifetime US3632444A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US78900868A 1968-12-31 1968-12-31
US78900768A 1968-12-31 1968-12-31

Publications (1)

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US3632444A true US3632444A (en) 1972-01-04

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Family Applications (2)

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US789007A Expired - Lifetime US3632444A (en) 1968-12-31 1968-12-31 Graphite anode treatment
US789008A Expired - Lifetime US3580824A (en) 1968-12-31 1968-12-31 Impregnated graphite

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US789008A Expired - Lifetime US3580824A (en) 1968-12-31 1968-12-31 Impregnated graphite

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US (2) US3632444A (OSRAM)
CA (1) CA938250A (OSRAM)
DE (1) DE1965359A1 (OSRAM)
FR (1) FR2027440A1 (OSRAM)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4169739A (en) * 1978-04-12 1979-10-02 Semix, Incorporated Method of making silicon-impregnated foraminous sheet by partial immersion and capillary action
US4171991A (en) * 1978-04-12 1979-10-23 Semix, Incorporated Method of forming silicon impregnated foraminous sheet by immersion
US4174234A (en) * 1978-04-12 1979-11-13 Semix, Incorporated Silicon-impregnated foraminous sheet
US4647353A (en) * 1986-01-10 1987-03-03 Mccready David Cathodic protection system
US4855027A (en) * 1986-01-10 1989-08-08 Mccready David F Carbosil anodes
US4921588A (en) * 1986-01-10 1990-05-01 Mccready David F Cathodic protection using carbosil anodes
US20080263864A1 (en) * 2007-04-30 2008-10-30 Snecma Turbomachine blade and turbomachine comprising this blade
US20100310447A1 (en) * 2009-06-05 2010-12-09 Applied Nanotech, Inc. Carbon-containing matrix with functionalized pores
US20110027603A1 (en) * 2008-12-03 2011-02-03 Applied Nanotech, Inc. Enhancing Thermal Properties of Carbon Aluminum Composites
US20110147647A1 (en) * 2009-06-05 2011-06-23 Applied Nanotech, Inc. Carbon-containing matrix with additive that is not a metal

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3018897A1 (de) * 1980-05-16 1981-12-10 Viktor Pavlovič Arčakov Elektrode fuer elektrochemische prozesse und verfahren zu ihrer herstellung
FR2487861A1 (fr) * 1980-07-30 1982-02-05 Sklyarov Alexandr Electrode pour processus electrochimiques et procede de fabrication de ladite electrode
US4341848A (en) * 1981-03-05 1982-07-27 The United States Of America As Represented By The United States Department Of Energy Bifunctional air electrodes containing elemental iron powder charging additive
US4448886A (en) * 1981-11-30 1984-05-15 Diamond Shamrock Corporation Biodispersions
US5318862A (en) * 1993-09-22 1994-06-07 Westinghouse Electric Corp. Bifunctional gas diffusion electrodes employing wettable, non-wettable layered structure using the mud-caking concept
DE4417744C1 (de) * 1994-05-20 1995-11-23 Bayer Ag Verfahren zur Herstellung stabiler Graphitkathoden für die Salzsäureelektrolyse und deren Verwendung
DE19752864A1 (de) * 1997-11-28 1999-06-02 Sgl Carbon Ag Imprägnierte Bürste aus Kohlenstoff für das Übertragen elektrischen Stromes

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA669472A (en) * 1963-08-27 Michael Humenik, Jr. Graphite structure
GB958376A (en) * 1959-09-14 1964-05-21 Ford Motor Co Graphite structure

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA669472A (en) * 1963-08-27 Michael Humenik, Jr. Graphite structure
GB958376A (en) * 1959-09-14 1964-05-21 Ford Motor Co Graphite structure

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4169739A (en) * 1978-04-12 1979-10-02 Semix, Incorporated Method of making silicon-impregnated foraminous sheet by partial immersion and capillary action
US4171991A (en) * 1978-04-12 1979-10-23 Semix, Incorporated Method of forming silicon impregnated foraminous sheet by immersion
US4174234A (en) * 1978-04-12 1979-11-13 Semix, Incorporated Silicon-impregnated foraminous sheet
US4647353A (en) * 1986-01-10 1987-03-03 Mccready David Cathodic protection system
WO1987004191A1 (en) * 1986-01-10 1987-07-16 Mccready David F Cathodic protection system
US4855027A (en) * 1986-01-10 1989-08-08 Mccready David F Carbosil anodes
US4921588A (en) * 1986-01-10 1990-05-01 Mccready David F Cathodic protection using carbosil anodes
US20080263864A1 (en) * 2007-04-30 2008-10-30 Snecma Turbomachine blade and turbomachine comprising this blade
US20110027603A1 (en) * 2008-12-03 2011-02-03 Applied Nanotech, Inc. Enhancing Thermal Properties of Carbon Aluminum Composites
US20100310447A1 (en) * 2009-06-05 2010-12-09 Applied Nanotech, Inc. Carbon-containing matrix with functionalized pores
US20110147647A1 (en) * 2009-06-05 2011-06-23 Applied Nanotech, Inc. Carbon-containing matrix with additive that is not a metal

Also Published As

Publication number Publication date
CA938250A (en) 1973-12-11
US3580824A (en) 1971-05-25
FR2027440A1 (OSRAM) 1970-09-25
DE1965359A1 (de) 1972-02-17

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Free format text: CHANGE OF NAME;ASSIGNOR:HOOKER CHEMICALS & PLASTICS CORP.;REEL/FRAME:004109/0487

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