GB2117791A - Platinum alloy catalysts - Google Patents

Platinum alloy catalysts Download PDF

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Publication number
GB2117791A
GB2117791A GB08305771A GB8305771A GB2117791A GB 2117791 A GB2117791 A GB 2117791A GB 08305771 A GB08305771 A GB 08305771A GB 8305771 A GB8305771 A GB 8305771A GB 2117791 A GB2117791 A GB 2117791A
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platinum
state
electron density
catalyst
density
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GB8305771D0 (en
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Bose Sudhangshu
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Raytheon Technologies Corp
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United Technologies Corp
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    • 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
    • H01M4/928—Unsupported catalytic particles; loose particulate catalytic materials, e.g. in fluidised state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/648—Vanadium, niobium or tantalum or polonium
    • B01J23/6482—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/652—Chromium, molybdenum or tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8913—Cobalt and noble metals
    • 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
    • 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
    • H01M2004/8689—Positive 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
    • H01M2300/0008—Phosphoric acid-based
    • 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Catalysts (AREA)
  • Inert Electrodes (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

A method is disclosed for improving the performance of noble metal catalysts such as platinum in catalyzed chemical reactions where the reduction of oxygen is a rate limiting step. The catalytic activity of the catalyst and thus, the rate of reaction is increased by increasing the electron density of state at the Fermi level of the catalyst. This can be accomplished, for example, by alloying the noble metal catalyst with materials which increase the electron density of state; i.e. by solid solution alloying. Among the elements which may be used are W,V,Mo,Co and Cr.

Description

SPECIFICATION Noble metal catalyzed reactions The field of art to which this invention pertains is noble metal catalysts and chemical reactions which are noble metal catalyzed.
In order for chemical reactions to be useful in many industrial processes, it is necessary for these reactions to take place at an accelerated rate. For example, a fuel cell is a device which converts the energy of a chemical reaction between a fuel and oxidant directly into low voltage, direct current electricity. To obtain a high efficiency of conversion, it is necessary that the reactions of the fuel and oxidant occur in such manner that the amount of energy degraded into heat is as small as possible. At the same time, the rates of reaction must be high enough to produce, economically, a useful amount of current from a cell of practical size.
Therefore, in the area of fuel cells, as in many other chemical production processes, combustion converters, etc., it is customary to incorporate catalysts which accelerate such reactions to make such processes industrially and commercially useful.
However, the art of catalysis still remains in large degree a little understood area. Additions and eliminations in compounded catalysts by and large take place in a trial and error manner in large measure governed by the results of a previous trial. An example of this is in the fuel cell area, where many patents have been issued on various combinations of catalytic material producing improved results with no real recognition of the reasons one catalyst may or may not perform better than another in this environment.
Note U.S. Patent Nos. 3340 097, 3 341 936,3 380 934, 3 428 490, 3 506 494, 3 615 836,4 127 469, 4136 059, 4 137372,4137373,4186110,4192907,4202934,and4316944.
Accordingly, what is needed in the area of catalyzed chemical reactions is a better understanding of the determinative factors which result in increased reaction rates so that reaction rates in particular areas of catalyzed reactions may be improved.
The present invention is directed to a method of improving catalyst performance and thus, rate of reaction in platinum catalyzed chemical reactions, where the reduction of oxygen is a rate limiting step. Such reaction rate is improved by increasing the electron density of state at the Fermi level of the platinum catalyst. This can be accomplished by such methods as alloying the catalysts, varying the alloy components of the catalyst, or varying the amounts of alloying components.
The foregoing, and other features and advantages of the present invention will become more apparent in light of the following description and accompanying drawings.
Figure 1 demonstrates a comparison of catalyst activity as a function of electron density of state in an isopropanol oxidation reaction.
Figures 2 and 3 demonstrate catalyst activity as a function of electron density of state in an electrochemical oxidation reaction.
In the following discussion of this invention and in the appended claims, when catalytic activity comparisons are made, they are intended to be comparisons of mass activity. Mass activity is an arbitrarily defined measure of the effectiveness of a catalyst per unit weight of the catalytically active component. For example, in the case of fuel cells with phosphoric acid as an electrolyte, the mass activity of the cathode catalyst is defined in milliamps per milligram as the maximum current available due to oxygen reduction as 0.90 volt, the potential being measured relative to an unpolarized hydrogen/platinum reference electrode at the same temperature and pressure in the same electrolyte. A greater mass activity can be achieved by either increasing a surface area of the catalyst or by increasing its specific activity.Specific activity is defined as the oxygen reduction current as specified above which is available per unit surface area of the noble metal.
Absorption and desorption are two important steps during the process of catalysis. For a material to be a successful catalyst in a process like oxygen reduction, the absorption bonds should not be so strong as to form a stable oxide, nor should it be so weak as not to have enough absorbed species to react. The absorption bond is controlled in part by the number of electrons, particularly in the d-orbitals, taking part in the formation of bonds such as in platinum-oxygen systems. If there are too many electrons available, that is a high electronic density of d-like states at the Fermi level (highest occupied electronic energy level at low temperature) a stable oxide forms, while if there are too few electrons, that is low electron density of d-like states at the Fermi level, available, the material does not show any significant catalytic activity.
According to the present invention, the electron density of states at the Fermi level are increased to improve the catalytic activity. The method consists of forming substitutional alloys using two or more elements. Alloying elements accept electrons from or donate electrons to the solvent metal (which is the base metal, e.g. platinum) and in turn, change the lattice parameter because the amount of overlap of the electron orbitals of neighboring atoms changes. This change will either increase or decrease the electron density of state at the Fermi level depending on whether electrons are accepted from or donated to the solvent metal.
For an alloy, the density of state has been found to be reduced by increasing the lattice parameter. On the other hand, an increase in the density of state may be achieved by reducing the lattice parameter. For example, the catalytic activity of platinum is enhanced when it is solid solution alloyed with certain transition metals. The alloying has been found to result in reduced lattice parameter and increased density of states at the Fermi level.
Since electron density of states can only be measured directly with great difficulty by complicated apparatus, the electron density of states were inferred from enhancement of paramagnetic susceptibility and from near edge X-ray absorption measurements. Paramagnetic susceptibility was measured by conventional methods, for example, using a vibrating sample magnetometer as described in Review of Scientific Instruments, vol. 30 (1959), page 548 by Simon Foner. X-ray absorption measurements were also performed utilizing conventional techniques by determining the amount of X-ray energy the samples were subjected to, allowing such energy to pass through the samples and measuring the transmitted intensity as a function of the energy of the incident X-ray beam. Such testing can be performed at such places as the Cornell High Energy Synchrotron facility at Cornell University.
Two examples verifying these results were demonstrated by noting the improvement in catalytic activity both in air oxidation (note Example 1) using differential scanning calorimetry (measured on a duPont 990 Thermal Analyzer in conjunction with the differential scanning calorimeter) where the temperature of onset of oxidation was seen to decrease with increasing electron density of state of the platinum alloys and in electrochemical oxygen reduction in phosphoric acid at 3500F (177 C) (note Example 2) where the specific activity at 0.9 volt increased on increased electron density of state. This data is demonstrated in the Table below.
TABLE Lattice Paramagnetic Temperature Half cell Material Parameter Susceptibility of Onset of Acticity A /gm Oxidation at 0.9V in D.S.C. clamps/ ( C) cm2 Pt 3.923 1.0 x 10-6 153 49.9 Pt-Mo 3.913 10.8 x 10-6 105 82.5 Pt-V 3.872 5.7 x 10-6 124 74.7 PT-W 3.916 3.4 x 10-6 143 68.2 Pt-Cr 3.865 Ferromagnetic 138 75.8 Pt-Mn 3.930 Ferromagnetic --- 72.4 This was further demonstrated by reducing the electron density of state at Fermi level of platinum by alloying with gold resulting in a reduction of catalytic activity. On adding gold to the platinum, the density of state of the platinum is reduced as reflected by the decrease in paramagnetic susceptibility.The specific activity decreased from 50 y amps/cm2 for platinum to 15 y amps/cm2 for the alloy as shown in Figure 2.
When altering the electron density of state by alloying the base metal must be selected first. Transition metals are preferred because they have appreciable density of d-like states at Fermi level. The alloying element is chosen based on its atomic size relative to the base metal so that the lattice parameter and electron density of state (as reflected by paramagnetic susceptibility) may be altered in the right direction. An example is a transition metal having unfilled d-like states with appreciable density of d-like states at Fermi level such as platinum. Its catalytic activity can be increased by increasing its density of state at the Fermi level. This may be achieved by substitutional alloying with transition metals, for example.Electron transfer has been shown to occur through paramagnetic susceptibility measurements (Figure 2) indicating that the density of state of the platinum has increased.
The method described herein has been found to be particularly suitable with platinum in such things as oxidation reactions and electrochemical oxygen reduction reactions. In both cases, the rate limiting step involves the reduction of oxygen.
Two tests were performed to further demonstrate the improvements according to the present invention.
Solid solutions of alloys of platinum were formed. It should be noted that it is critical to keep the platinum face center cubic structure intact while increasing its electron density of state. It is also important to select only those alloys in which the electronic density of state at Fermi level increases because of alloying. The improvement in electron density of state at Fermi level may be determined by measuring the paramagnetic susceptibility which is proportional to electron density of state at Fermi level. The density of state may also be determined by measuring the difference in X-ray absorption peak area of alloyed and unalloyed platinum (note Example 3) that arises because of transitions from the filled p-states to the empty d-states.
The alloys thus formed were then tested in the oxidation of isopropyl alcohol and in electrochemical oxygen reduction to demonstrate that the increased electron density of state increased the rate of reaction and catalytic activity of the platinum.
Example 1 Air saturated with isopropyl alcohol was passed over the respective catalyst which was slowly heated in a differential scanning calorimeter (D.S.C.). The onset of oxidation of the alcohol was determined from a sudden surge of heat. The temperature corresponding to the onset of oxidation was plotted against the paramagnetic susceptibility of platinum and the respective alloy catalysts. This is shown in Figure 1. It is clear that oxidation commences at a lower temperature the more paramagnetic the alloy is. The data thus indicates that the higher electron density of state at Fermi level, the lower the temperature of oxidation.
Example 2 Figure 2 is a plot of the electrochemical activity of the catalysts for oxygen reduction in phosphoric acid plotted as a function of their paramagnetic susceptibility. Testing was performed as described above in a conventional electrochemical cell at 0.9 volt using phosphoric acid as the electrolyte. Again, it is clear that the higher the paramagnetic susceptibility (the higher the electron density of state at Fermi level) the higher the catalytic activity. An alloy which has a lower density of state than that of platinum is platinum with 10% gold. Figure 2 shows that for this alloy, the catalytic activity is in fact, lower than that of the platinum. Figure 3 is a plot of catalytic activity of oxygen reduction in phosphoric acid against the difference in X-ray absorption peak area of the alloyed platinum and unalloyed platinum.These measurements were made following the method described in the Journal of Chemical Physics, vol. 70, No. 11 (June 1, 1979), pages 4849-4855 by F.W.
Lytle et al. This plot includes ferromagnetic alloys suggesting that the density of states correlation does hold for these alloys as well, even though a direct paramagnetic-electron density of state analogy cannot be shown for these alloys.
An exemplary process for allowing noble metal catalysts of this invention comprises absorbing, for example, a chromium containing species, preferably in the anion form on the supported noble metal catalyst followed by heating the chromium impregnated catalyst in a reducing atmosphere to promote the alloy formation. The preferred anion as recited is the chromate and for other alloys, the vanadate, manganate, molybdate and tungstate anion form respectively. While this method is equally well suited to making unsupported as well as supported alloys, finely divided unsupported noble metals are limited generally to less than 50 m2/gm of noble metal. Accordingly, this method is best practiced by using supported finely divided noble metals which can be prepared in surface areas generally greater than 100 m2/gm of noble metal. Note commonly assigned U.S.Patent 4316944.
Although this invention has been demonstrated specifically for platinum, any noble metal can be improved in performance in similarfashion. Furthermore, while this invention has particular applicability to fuel cells, any chemical reactions involved in producing chemical, pharmaceutical, automotive, or antipollution reactions have similar applicability. And as stated, the invention has particular utility as electrocatalystsforthe reduction of oxygen. This activity makes these catalysts particularly suitable in an acid fuel cell. However, the use is not limited to fuel cells and they can be used in any environment where oxygen reduction, and especially electrochemical oxygen reduction takes place as part of the process.
Although this invention has been shown and described with respect to detailed embodiments thereof, it should be understood by those skilled in the art that various changes and omissions in form and detail may be made therein without departing from the scope of the invention.

Claims (3)

1. Process for improving the catalyst performance in a platinum catalyzed chemical reaction where the reduction of oxygen is a rate limiting step, characterized in increasing the rate of the chemical reaction by increasing the electron density of state at the Fermi level of the platinum catalyst.
2. The method according to claim 1, characterized in that the electron density of state is increased by alloying the platinum catalyst.
3. The method according to claim 1, characterized in that the reaction is an electrochemical oxidation reaction.
GB08305771A 1982-03-31 1983-03-02 Platinum alloy catalysts Withdrawn GB2117791A (en)

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AU (1) AU1255683A (en)
BE (1) BE896315A (en)
BR (1) BR8301586A (en)
CA (1) CA1207310A (en)
DE (1) DE3310965A1 (en)
DK (1) DK95983A (en)
EG (1) EG16278A (en)
FI (1) FI831107L (en)
FR (1) FR2524340B1 (en)
GB (1) GB2117791A (en)
IL (1) IL68099A0 (en)
IT (1) IT1160756B (en)
NL (1) NL8300822A (en)
NO (1) NO831099L (en)
SE (1) SE8301300L (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2133420A (en) * 1983-01-17 1984-07-25 United Technologies Corp Ternary fuel cell catalysts containing platinum and cobalt
EP0149293A1 (en) * 1984-01-18 1985-07-24 Engelhard Corporation Improved electrocatalyst and fuel cell electrode using the same
EP0165024A2 (en) * 1984-06-07 1985-12-18 Giner, Inc. Cathode alloy electrocatalysts
US5939220A (en) * 1996-10-25 1999-08-17 Johnson Matthey Public Limited Company Catalyst

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH031810A (en) * 1989-05-30 1991-01-08 Matsushita Electric Ind Co Ltd Kitchen system
JP2001015122A (en) * 1999-06-30 2001-01-19 Tanaka Kikinzoku Kogyo Kk Catalyst for polymer solid electrolyte type fuel cell and solid electrolyte type fuel cell
JP2002198057A (en) * 2000-05-23 2002-07-12 National Institute Of Advanced Industrial & Technology Fuel cell and improved version of oxygen electrode used for same

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB133261A (en) * 1919-04-22 1919-10-09 Allen Warwick Smith Improvements in Carrying and Drag Bags.
GB407893A (en) * 1932-11-02 1934-03-29 Norsk Hydro Elektrisk Improvements in catalyst for the oxidation of ammonia
GB489306A (en) * 1937-01-25 1938-07-25 Ig Farbenindustrie Ag Catalysts
GB491143A (en) * 1937-01-26 1938-08-26 Ig Farbenindustrie Ag Catalysts
GB570071A (en) * 1941-06-30 1945-06-21 Alan Richard Powell Improvements in the oxidation of ammonia to oxides of nitrogen
GB1016058A (en) * 1963-09-30 1966-01-05 Johnson Matthey Co Ltd Improvements in and relating to catalysts
GB1108317A (en) * 1964-11-24 1968-04-03 Exxon Research Engineering Co Catalyst composition
GB1124504A (en) * 1964-08-21 1968-08-21 Johnson Matthey Co Ltd Improvements in and relating to catalysts
GB1299540A (en) * 1970-04-01 1972-12-13 Inst Neftechimicheskogo Sintez Dehydrogenation, dehydrocyclization and hydrodealkylation catalysts
GB1336316A (en) * 1969-11-27 1973-11-07 Inst Neftechimicheskogo Sintez Method of hydrogenation or hydrodealkylation hydrocarbons
GB2078254A (en) * 1980-06-18 1982-01-06 United Technologies Corp Noble metal-chromium alloy catalysts

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB133261A (en) * 1919-04-22 1919-10-09 Allen Warwick Smith Improvements in Carrying and Drag Bags.
GB407893A (en) * 1932-11-02 1934-03-29 Norsk Hydro Elektrisk Improvements in catalyst for the oxidation of ammonia
GB489306A (en) * 1937-01-25 1938-07-25 Ig Farbenindustrie Ag Catalysts
GB491143A (en) * 1937-01-26 1938-08-26 Ig Farbenindustrie Ag Catalysts
GB570071A (en) * 1941-06-30 1945-06-21 Alan Richard Powell Improvements in the oxidation of ammonia to oxides of nitrogen
GB1016058A (en) * 1963-09-30 1966-01-05 Johnson Matthey Co Ltd Improvements in and relating to catalysts
GB1124504A (en) * 1964-08-21 1968-08-21 Johnson Matthey Co Ltd Improvements in and relating to catalysts
GB1108317A (en) * 1964-11-24 1968-04-03 Exxon Research Engineering Co Catalyst composition
GB1336316A (en) * 1969-11-27 1973-11-07 Inst Neftechimicheskogo Sintez Method of hydrogenation or hydrodealkylation hydrocarbons
GB1299540A (en) * 1970-04-01 1972-12-13 Inst Neftechimicheskogo Sintez Dehydrogenation, dehydrocyclization and hydrodealkylation catalysts
GB2078254A (en) * 1980-06-18 1982-01-06 United Technologies Corp Noble metal-chromium alloy catalysts

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2133420A (en) * 1983-01-17 1984-07-25 United Technologies Corp Ternary fuel cell catalysts containing platinum and cobalt
EP0149293A1 (en) * 1984-01-18 1985-07-24 Engelhard Corporation Improved electrocatalyst and fuel cell electrode using the same
EP0165024A2 (en) * 1984-06-07 1985-12-18 Giner, Inc. Cathode alloy electrocatalysts
EP0165024A3 (en) * 1984-06-07 1987-08-19 Giner, Inc. Cathode alloy electrocatalysts
US5939220A (en) * 1996-10-25 1999-08-17 Johnson Matthey Public Limited Company Catalyst

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FI831107L (en) 1983-10-01
BE896315A (en) 1983-07-18
IL68099A0 (en) 1983-06-15
DK95983A (en) 1983-10-01
SE8301300L (en) 1983-10-01
SE8301300D0 (en) 1983-03-10
NL8300822A (en) 1983-10-17
IT8320266A0 (en) 1983-03-24
FR2524340A1 (en) 1983-10-07
CA1207310A (en) 1986-07-08
DK95983D0 (en) 1983-02-28
BR8301586A (en) 1983-12-06
IT1160756B (en) 1987-03-11
FI831107A0 (en) 1983-03-30
FR2524340B1 (en) 1987-08-14
AU1255683A (en) 1983-10-06
NO831099L (en) 1983-10-03
GB8305771D0 (en) 1983-04-07
EG16278A (en) 1987-04-30
JPS58177145A (en) 1983-10-17
DE3310965A1 (en) 1983-10-13

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