EP0259424A1 - Electrode for oxidising methanol - Google Patents

Electrode for oxidising methanol

Info

Publication number
EP0259424A1
EP0259424A1 EP87901557A EP87901557A EP0259424A1 EP 0259424 A1 EP0259424 A1 EP 0259424A1 EP 87901557 A EP87901557 A EP 87901557A EP 87901557 A EP87901557 A EP 87901557A EP 0259424 A1 EP0259424 A1 EP 0259424A1
Authority
EP
European Patent Office
Prior art keywords
electrode
carbon
electrode according
substrate
catalyst
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.)
Withdrawn
Application number
EP87901557A
Other languages
German (de)
French (fr)
Inventor
John Bannister Goodenough
Andrew Hamnett
Ramasamy Manoharan
Brendan James Kennedy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Research Development Corp UK
Original Assignee
National Research Development Corp UK
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from GB868604982A external-priority patent/GB8604982D0/en
Priority claimed from GB868622455A external-priority patent/GB8622455D0/en
Application filed by National Research Development Corp UK filed Critical National Research Development Corp UK
Publication of EP0259424A1 publication Critical patent/EP0259424A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
    • H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
    • H01M2004/8684—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0002—Aqueous electrolytes
    • H01M2300/0005—Acid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0002—Aqueous electrolytes
    • H01M2300/0005—Acid electrolytes
    • H01M2300/0011—Sulfuric acid-based
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0002—Aqueous electrolytes
    • H01M2300/0014—Alkaline electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/921—Alloys or mixtures with metallic elements
    • 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

  • an electrode for oxidising methanol comprises a preferably porous substrate which is an electronic conductor capable of reducing elemental oxygen to water yielding not more than 5% (preferably not more than 1%, more preferably not more than 0.1%) hydrogen peroxide, to which substrate is attached a catalyst comprising platinum and either or both of ruthenium and titanium dioxide.
  • a preferred suitable substrate is carbon of an ash content less than 0.1%, preferably less than 0.05%, preferably not more than 0.01%.
  • An example of such a carbon is 'coconut carbon', which is derived from coconut shells by converting these to charcoal, washing and comminuting the charcoal, and exposing the comminuted charcoal to gas, preferably first carbon dioxide and optionally afterwards ammonia or the latter by itself.
  • An alternative suitable gas is steam.
  • carbon for example sold by Cabot Corporation under the Trade Mark
  • Vulcan XC-72 which is of poorly crystalline type and has a surface area of at least 200 m 2 /g, a mean particle size in the range 5 nm to 50 nm, and an apparent density of 80 to 110 kg/m 3 , which may be treated by comminuting it and exposing it to gas at elevated temperature.
  • the carbon before the comminution has a surface area of not more than 300 m 2 /g.
  • the carbon before the comminution has a pH below 7.
  • the carbon may be exposed to only carbon dioxide, for example at 800oC to 1000oC, preferably for 40 to 90 minutes, such as 900oC for 1 hour.
  • Catalyst loadings may be 1 to 15% by weight of the substrate, preferably 2 to 12%.
  • the invention extends to a fuel cell including an electrode as set forth above.
  • the invention also provides a method of oxidising methanol, comprising contacting methanol and water at an electrode as set forth above and applying to the electrode a potential more positive than -0.3 volts with respect to the Hg/Hg 2 SO 4 electrode.
  • the invention provides a method of making an electrode as set forth above, comprising applying a solution containing a platinum and a ruthenium compound onto the substrate and decomposing the compounds, whereby the desired catalyst is precipitated on, and is attached to, the substrate.
  • the substrate is mixed with a titanium compound which is decomposed to form titanium dioxide.
  • the invention extends to the electrode so made, and to fuel cells, methods of oxidising methanol etc. using it.
  • the 'coconut' carbon is preferred.
  • the poorly crystalline carbon is preferred.
  • Figures 1 and 2 show the potential versus current density obtained for various electrodes in 2.5M H 2 SO 4 , 1M MeOH.
  • Figure 3 shows the specific activities for some of these electrodes.
  • Figure 4 shows lifetime data.
  • a porous carbon electrode is made utilising Vulcan XC-72 carbon.
  • High-surface-area Vulcan XC-72 carbon was obtained from the Cabot Corp., Billerica, MA. The ash content of this carbon was found to be about 0.05%. The other physical and chemical parameters of this carbon are as follows:
  • Platinum has been dispersed into the gas-activated carbon by reducing chloroplatinic acid with sodium formate solution as described elsewhere. This procedure (yielding comparative electrodes) yields fine platinum particles of uniform size (about 63A diameter) on a carbon substrate.
  • Chloroplatinic acid solution containing the required proportion of platinum was taken from a 2 weight % stock solution, mixed with half of its volume of isopropanol, and neutralised with a dilute solution of sodium carbonate.
  • An appropriate quantity of gas-activated Vulcan XC-72 carbon was added, and the entire mixture was dried in an air oven before it was added, with vigorous stirring, to an excess of boiling 5 weight % sodium formate solution to reduce the chloroplatinic acid to platinum metal.
  • the resulting mass was filtered and washed repeatedly with hot, distilled water before being dried in an air oven.
  • a supported Pt-Ru- catalyst was prepared by co-impregnation of the gas-activated Vulcan XC-72 carbon with a mixed solution containing appropriate amounts of chloroplatinic acid H 2 PtCl 6 and ruthenium trichloride RuCl 3 .
  • the impregnated carbon was evaporated to dryness and reduced at 200oC for 20 hours in flowing H 2 .
  • Teflon-bonded electrodes were prepared for electrochemical measurements.
  • the Teflon binder provides the necessary mechanical strength to prevent electrode collapse under the gas pressure required for gas-electrolyte interface control in a gas-diffusion electrode, and it does so while retaining the necessary electrode porosity.
  • the Teflon-bonded electrodes were made as follows: Tetrahydrofuran (THF) was added to a measured quantity of catalysed substrate powder in a beaker, and the mixture was agitated in an ultrasonic bath for about 30 minutes before a few ml of dilute suspension of Teflon emulsion (ICI GP2 Fluon dispersion, particle size 0.1-0.2 microns) was added to the mixture without interruption of the agitation.
  • THF Tetrahydrofuran
  • the product material was centrifuged repeatedly with THF and finally spread on a platinum expanded-metal (Exmet) screen (0.076 mm diameter wire, 1024 mesh cm -2 ).
  • the coated screen was air-dried for about 15 minutes before it was cold-pressed at 125 kg cm -2 for 5 minutes.
  • the pressed mass was dried for 2 hours at 110oC and then cured in air at 360oC for 30 minutes.
  • the -Teflon content of the electrodes was optimal at 25 to 35% by volume, the content in each case being 30% unless otherwise stated on the Figure.
  • the platinum loading was 3% on Figure 1 and 5% on Figure 2.
  • the BET surface area of such a substrate was about 600 m 2 /g and the resistivity about 0.4 ohm cm.
  • Comparative Pt-Ru electrodes have been made by compressing Pt-Ru alloy onto a platinum mesh at a pressure of 1.7 tonne cm -2 .
  • An electrochemical cell for measuring electrochemical performance parameters was set up containing this substrate as a working electrode, a Hg/Hg 2 So 4 , H + reference electrode, a high surface area flatbed counter electrode, and an electrolyte, which was a solution of 2.5M sulphuric acid H 2 SO 4 and 1M methanol CH 3 OH in distilled water.
  • a platinum/titanium dioxide/treated carbon electrode was made as follows. 400 mg of gas treated Vulcan XC-72 was suspended in 100 ml of water and heated to boiling. A dilute solution of titanium (IV) isoproproxide in isopropanol was slowly added and the solution boiled for 1 hour. The pH was then adjusted to 12 with NH 3 OH. A 2% chloroplatinic acid solution was then added and after a further hour the solution brought to dryness. The resulting solid was dried at 110 for 12 hours, re-suspended in water and a five-fold excess of HCOONa added. The mixture was then boiled for 2 hours, filtered, washed with boiling distilled water and dried at 110°. The electrode was made as described previously for platinised carbon electrodes and had the composition: Pt-7%, TiO 2 -3%, C t -63%, Teflon 27%. EXAMPLE 3
  • a platinum/ruthenium/titanium dioxide/treated carbon electrode was made as follows. 600 mg of gas treated Vulcan XC-72 was suspended in 100 ml of water and heated to boiling. A dilute solution of Titanium (IV) isopropoxide in isopropanol was slowly added followed by 2% solutions of chloroplatanic acid and ruthenium trichloride in water. The resulting solution was neutralised with a dilute solution of sodium hydrogen carbonate. The slurry was brought to dryness, dried at 110 for 12 hours, re-suspended in water, reduced with HCOONa, filtered, washed with water and finally dried as above.

Abstract

Une électrode à oxyder du méthanol comprend un substrat de préférence poreux, qui est un conducteur électronique pouvant réduire des éléments d'oxygène en eau, en ne produisant pas plus de 5% de péroxyde d'hydrogène, un catalyseur comprenant du platine et du ruthénium, ou du platine et du bioxyde de titane, ou tous les trois étant fixé audit substrat.An electrode for oxidizing methanol comprises a preferably porous substrate, which is an electronic conductor capable of reducing oxygen elements in water, by producing not more than 5% of hydrogen peroxide, a catalyst comprising platinum and ruthenium , or platinum and titanium dioxide, or all three being attached to said substrate.

Description

ELECTRODE FOR OXIDISING METHANOL This invention relates to an electrode for oxidising methanol, to a fuel cell including such an electrode, to a method of oxidising methanol at such an electrode, and to a method of making certain such electrodes. According to the present Invention, an electrode for oxidising methanol comprises a preferably porous substrate which is an electronic conductor capable of reducing elemental oxygen to water yielding not more than 5% (preferably not more than 1%, more preferably not more than 0.1%) hydrogen peroxide, to which substrate is attached a catalyst comprising platinum and either or both of ruthenium and titanium dioxide.
A preferred suitable substrate is carbon of an ash content less than 0.1%, preferably less than 0.05%, preferably not more than 0.01%. An example of such a carbon is 'coconut carbon', which is derived from coconut shells by converting these to charcoal, washing and comminuting the charcoal, and exposing the comminuted charcoal to gas, preferably first carbon dioxide and optionally afterwards ammonia or the latter by itself. An alternative suitable gas is steam. Another example is carbon (for example sold by Cabot Corporation under the Trade Mark
Vulcan XC-72) which is of poorly crystalline type and has a surface area of at least 200 m2/g, a mean particle size in the range 5 nm to 50 nm, and an apparent density of 80 to 110 kg/m3, which may be treated by comminuting it and exposing it to gas at elevated temperature. Preferably the carbon before the comminution has a surface area of not more than 300 m2/g. Preferably the carbon before the comminution has a pH below 7. The carbon may be exposed to only carbon dioxide, for example at 800ºC to 1000ºC, preferably for 40 to 90 minutes, such as 900ºC for 1 hour. Catalyst loadings may be 1 to 15% by weight of the substrate, preferably 2 to 12%. The invention extends to a fuel cell including an electrode as set forth above. The invention also provides a method of oxidising methanol, comprising contacting methanol and water at an electrode as set forth above and applying to the electrode a potential more positive than -0.3 volts with respect to the Hg/Hg2SO4 electrode.
According to another aspect, the invention provides a method of making an electrode as set forth above, comprising applying a solution containing a platinum and a ruthenium compound onto the substrate and decomposing the compounds, whereby the desired catalyst is precipitated on, and is attached to, the substrate. Preferably the substrate is mixed with a titanium compound which is decomposed to form titanium dioxide. The invention extends to the electrode so made, and to fuel cells, methods of oxidising methanol etc. using it. For use in alkaline media, the 'coconut' carbon is preferred. For use in acid media, the poorly crystalline carbon is preferred.
The invention will now be described by way of example. In the accompanying drawings, Figures 1 and 2 show the potential versus current density obtained for various electrodes in 2.5M H2SO4, 1M MeOH. Figure 3 shows the specific activities for some of these electrodes. Figure 4 shows lifetime data. In Figures 1 to 3, some electrodes not according to the invention are included for comparison. A porous carbon electrode is made utilising Vulcan XC-72 carbon.
High-surface-area Vulcan XC-72 carbon was obtained from the Cabot Corp., Billerica, MA. The ash content of this carbon was found to be about 0.05%. The other physical and chemical parameters of this carbon are as follows:
Surface area 257 m2/g
Mean particle size 30 nm
Approximate density 96 kg/m3 pH 5 This carbon was subjected to mechanical grinding and then gas-activated by heating in a CO2 atmosphere at 900ºC for 1 hour. Gas activation rather than continued grinding was chosen to minimise particle agglomeration; it produced a 27% weight loss of the carbon, increased the effective surface area, and modified the surface. Titanium dioxide is impregnated into the carbon by mixing an appropriate amount of titanium (IV) isopropoxide with the carbon and allowing it to hydrolyse in air.
Platinum has been dispersed into the gas-activated carbon by reducing chloroplatinic acid with sodium formate solution as described elsewhere. This procedure (yielding comparative electrodes) yields fine platinum particles of uniform size (about 63A diameter) on a carbon substrate. Chloroplatinic acid solution containing the required proportion of platinum was taken from a 2 weight % stock solution, mixed with half of its volume of isopropanol, and neutralised with a dilute solution of sodium carbonate. An appropriate quantity of gas-activated Vulcan XC-72 carbon was added, and the entire mixture was dried in an air oven before it was added, with vigorous stirring, to an excess of boiling 5 weight % sodium formate solution to reduce the chloroplatinic acid to platinum metal. The resulting mass was filtered and washed repeatedly with hot, distilled water before being dried in an air oven. EXAMPLE 1 Platinum and ruthenium are to be co-deposited, in the atomic ratio Pt:Ru= 7:3.
A supported Pt-Ru- catalyst was prepared by co-impregnation of the gas-activated Vulcan XC-72 carbon with a mixed solution containing appropriate amounts of chloroplatinic acid H2PtCl6 and ruthenium trichloride RuCl3. The impregnated carbon was evaporated to dryness and reduced at 200ºC for 20 hours in flowing H2.
Teflon-bonded electrodes were prepared for electrochemical measurements. The Teflon binder provides the necessary mechanical strength to prevent electrode collapse under the gas pressure required for gas-electrolyte interface control in a gas-diffusion electrode, and it does so while retaining the necessary electrode porosity. The Teflon-bonded electrodes were made as follows: Tetrahydrofuran (THF) was added to a measured quantity of catalysed substrate powder in a beaker, and the mixture was agitated in an ultrasonic bath for about 30 minutes before a few ml of dilute suspension of Teflon emulsion (ICI GP2 Fluon dispersion, particle size 0.1-0.2 microns) was added to the mixture without interruption of the agitation. The product material was centrifuged repeatedly with THF and finally spread on a platinum expanded-metal (Exmet) screen (0.076 mm diameter wire, 1024 mesh cm-2). The coated screen was air-dried for about 15 minutes before it was cold-pressed at 125 kg cm-2 for 5 minutes. The pressed mass was dried for 2 hours at 110ºC and then cured in air at 360ºC for 30 minutes. The -Teflon content of the electrodes was optimal at 25 to 35% by volume, the content in each case being 30% unless otherwise stated on the Figure. The platinum loading was 3% on Figure 1 and 5% on Figure 2. The BET surface area of such a substrate was about 600 m2/g and the resistivity about 0.4 ohm cm.
Comparative Pt-Ru electrodes have been made by compressing Pt-Ru alloy onto a platinum mesh at a pressure of 1.7 tonne cm-2. An electrochemical cell for measuring electrochemical performance parameters was set up containing this substrate as a working electrode, a Hg/Hg2So4, H+ reference electrode, a high surface area flatbed counter electrode, and an electrolyte, which was a solution of 2.5M sulphuric acid H2SO4 and 1M methanol CH3OH in distilled water.
Platinum-black electrodes and platinum dispersed on normal carbon electrodes are easily poisoned. However, if carbon is treated with C0„ at 900ºC, and ruthenium is jointly dispersed with the platinum, good stability and performance are obtained, as may be seen from the Figures.
Interesting features of these figures are significant improvement in performance at higher electrolyte temperature, high current densities, decrease in the otherwise rapid rise in overpotential for the first few mA, and enhanced performance in terms of the electrode design. The poisoning mentioned above is tentatively believed to result from poisoning of platinum itself. This can be slowed, i.e. lifetime can be lengthened, by having fine dispersed platinum particles, hence the preference for in situ chemical formation of the platinum on the substrate. Meanwhile, the carbon treatment mentioned above gives, as shown, a useful decrease in overpotential. The combination of decrease in overpotential and longer life is valuable.
Comparison of current-potential curves with the curves of potential versus current per mg of platinum shows that significant reduction in cost is achieved by deposition of the Pt-Ru catalyst onto the activated carbon substrate. The service-life data for various electrodes are presented in
Figure 4. A power density of about 80 mW cm-2 could be achieved if one were to combine the methanol anode (Pt-Ru/Ct) and an oxygen reducing cathode. EXAMPLE 2
A platinum/titanium dioxide/treated carbon electrode was made as follows. 400 mg of gas treated Vulcan XC-72 was suspended in 100 ml of water and heated to boiling. A dilute solution of titanium (IV) isoproproxide in isopropanol was slowly added and the solution boiled for 1 hour. The pH was then adjusted to 12 with NH3OH. A 2% chloroplatinic acid solution was then added and after a further hour the solution brought to dryness. The resulting solid was dried at 110 for 12 hours, re-suspended in water and a five-fold excess of HCOONa added. The mixture was then boiled for 2 hours, filtered, washed with boiling distilled water and dried at 110°. The electrode was made as described previously for platinised carbon electrodes and had the composition: Pt-7%, TiO2-3%, Ct-63%, Teflon 27%. EXAMPLE 3
A platinum/ruthenium/titanium dioxide/treated carbon electrode was made as follows. 600 mg of gas treated Vulcan XC-72 was suspended in 100 ml of water and heated to boiling. A dilute solution of Titanium (IV) isopropoxide in isopropanol was slowly added followed by 2% solutions of chloroplatanic acid and ruthenium trichloride in water. The resulting solution was neutralised with a dilute solution of sodium hydrogen carbonate. The slurry was brought to dryness, dried at 110 for 12 hours, re-suspended in water, reduced with HCOONa, filtered, washed with water and finally dried as above.

Claims

1. An electrode for oxidising methanol, comprising a substrate which is an electronic conductor capable of reducing elemental oxygen to water yielding not more than 5% hydrogen peroxide, to which substrate is attached a catalyst comprising platinum and either one or both of titanium dioxide and ruthenium.
2. An electrode according to Claim 1, wherein the substrate is porous.
3. An electrode according to Claim 1 or 2, wherein the electronic conductor is capable of reducing elemental oxygen to water yielding not more than 1% hydrogen peroxide.
4. An electrode according to Claim 3, wherein the electronic conductor is capable of reducing elemental oxygen to water yielding not more than 0.1% hydrogen peroxide.
5. An electrode according to any preceding claim, wherein the catalyst comprises (i) Pt and Ru; or (ii) Pt and TiO2; or (iii) Pt and Ru- and TiO2.
6. An electrode according to any preceding claim, wherein the substrate is carbon of an ash content less than 0.1%.
7. An electrode according to Claim 6, wherein the carbon is 'coconut carbon', which is derived from coconut shells by converting these to charcoal, washing and comminuting the charcoal, and exposing the comminuted charcoal to gas,
8. An electrode according to Claim 7, wherein said gas to which the comminuted charcoal is exposed is carbon dioxide or is ammonia or is carbon dioxide followed by ammonia or is steam.
9. An electrode according to Claim 6, wherein the carbon is of poorly crystalline type and has a surface area of at least 200 m2/g, a mean particle size in the range 5 nm to 50 nm, and an apparent density of 80 to 110 kg/m3
10. An electrode according to Claim 9, wherein the carbon is treated by comminuting it and exposing it to gas at elevated temperature.
11. An electrode according to Claim 10, wherein the carbon before the comminution has a surface area of not more than 300 m2/g.
12. An electrode according to Claim 10 or 11, wherein the carbon before the comminution has a pH below 7.
13. An electrode according to any of Claims 10 to 12, wherein the carbon is exposed to only carbon dioxide.
14. An electrode according to Claim 13, wherein the exposure is for 40 to 90 minutes at 800°C to 1000°C.
15. An electrode according to any preceding claim, wherein the catalyst is present in a proportion of from 1 to 15% by weight of the substrate.
16. An electrode according to Claim 15, wherein the catalyst is present in a proportion of from 2 to 12% by weight of the substrate.
17. A method of making an electrode as claimed in any preceding claim, comprising applying a solution containing a platinum and a ruthenium compound onto the substrate and decomposing the compounds, whereby the desired catalyst is precipitated on, and is attached to, the substrate.
18. A method according to Claim 17, wherein the substrate is mixed with a titanium compound which is decomposed to form titanium dioxide.
19. A fuel cell wherein methanol is oxidised at an electrode, the electrode being as claimed in any of Claims 1 to 16 or having been made by a method according to Claim 17 or 18.
20. A method of oxidising methanol, comprising contacting methanol and water at an electrode as claimed in any of Claims 1 to 16 or having been made by a method according to Claim 17 or 18, and applying to the electrode a potential more positive than -0.3 volts with respect to the Hg/Hg2SO4 electrode.
EP87901557A 1986-02-28 1987-02-26 Electrode for oxidising methanol Withdrawn EP0259424A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB868604982A GB8604982D0 (en) 1986-02-28 1986-02-28 Electrode for oxidising methanol
GB8604982 1986-02-28
GB8622455 1986-09-18
GB868622455A GB8622455D0 (en) 1986-09-18 1986-09-18 Electrode

Publications (1)

Publication Number Publication Date
EP0259424A1 true EP0259424A1 (en) 1988-03-16

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Family Applications (1)

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EP87901557A Withdrawn EP0259424A1 (en) 1986-02-28 1987-02-26 Electrode for oxidising methanol

Country Status (3)

Country Link
EP (1) EP0259424A1 (en)
GB (1) GB2187880A (en)
WO (1) WO1987005445A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9507012D0 (en) * 1995-04-05 1995-05-31 Johnson Matthey Plc Improved electrode

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3212936A (en) * 1960-11-07 1965-10-19 Air Prod & Chem Method of forming paste-form fuel cell electrode
GB1163479A (en) * 1967-03-17 1969-09-04 Engelhard Min & Chem Fuel Electrodes
GB1409260A (en) * 1971-12-29 1975-10-08 Exxon Research Engineering Co Fuel cell having non-alloyed palladium-ruthenium anode catalyst
GB1501102A (en) * 1974-02-19 1978-02-15 Shell Int Research Method for the production of a composite catalyst suitable for use in forming fuel cell electrodes
US3964933A (en) * 1974-04-08 1976-06-22 Exxon Research And Engineering Company Carbon article including electrodes and methods of making the same
US4028274A (en) * 1976-06-01 1977-06-07 United Technologies Corporation Support material for a noble metal catalyst and method for making the same
JPS5679858A (en) * 1979-12-04 1981-06-30 Hitachi Ltd Liquid-penetrable electrode for fuel battery
GB2095025B (en) * 1981-03-17 1984-11-21 Hitachi Ltd Acid electrolyte fuel cell
GB2164785B (en) * 1984-09-06 1988-02-24 Nat Res Dev Electrode for reducing oxygen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8705445A1 *

Also Published As

Publication number Publication date
WO1987005445A1 (en) 1987-09-11
GB2187880A (en) 1987-09-16
GB8704526D0 (en) 1987-04-01

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