 Fuel cell cooled by latent heat of water evaporation |
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| Pulsating gas-assisted injection molding apparatus |
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| Composite electrodes |
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| Electrode substrate for fuel cell |
| What is claimed is: 1. An electrode substrate for a fuel cell, which substrate is in contact with ... |
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| Electrode substrate for fuel cell and process for producing the same |
| Primary object of hte present invention is to provide a substrate and a process for producing the ... |
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| Gas separator for a fuel cell, and fuel cell using the same gas separator for a fuel cell |
| It is hence an object of the present invention to solve the above problems, and enhance the feed ... |
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| Fuel cell and method of ameliorating temperature distribution thereof |
| One object of the present invention is to provide a fuel cell whose temperature distributions have ... |
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Process for preparing a membrane/electrode assembly
| Details |
Inventors: Mussell, Robert D.;
Assignee: The Dow Chemical Company (Midland, MI)
Primary Examiner: Skapars; Anthony
Assistant Examiner:
Attorney, Agent or Firm: Galbraith; Ann K.
A composition comprising (a) catalytically-active particles, (b) an organic compound having a pKa of at least about 18 and a basicity parameter, .beta., of less than 0.66, and (c) a polymeric binder. Also described is a process for preparing a membrane/electrode assembly, which comprises the sequential steps of (i) applying a layer of the composition of the invention to a solid polymer electrolyte, a carbon fiber paper, or a release substrate; (ii) heating the composition under conditions sufficient to volatilize at least 95 percent of component (b); and (iii) positioning the composition in contact with the solid polymer electrolyte, if the composition was not applied directly to the solid polymer electrolyte, forming the membrane/electrode assembly thereby. It has been discovered that the composition and process of the invention, when used to prepare a membrane electrode assembly (MEA) having a solid polymer electrolyte, provides an MEA which provides a relatively high voltage at a given current density and gas flow rate in a fuel cell. |
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DETAILED DESCRIPTION OF THE INVENTION The term "catalytically-active particles" as used herein refers to particles of a metal or compound which is catalytic for the electroreduction of oxygen or electrooxidation of hydrogen or methanol under the pressure and temperature conditions in the fuel cell.
Examples of such particles which are useful include particles of platinum, ruthenium, gold, palladium, rhodium, iridium, electroconductive and reduced oxides thereof, and alloys of such materials, either in combination with each other or with other transition metals.
The particles may be supported on a suitable material, if desired, such as carbon black.
Preferably, the catalytically-active particles are platinum particles supported on carbon, which preferably contain from about 10 percent to about 30 percent by weight of platinum.
The size of the catalyst particles (on an unsupported basis) is preferably at least about 10 A.
degree.
, more preferably at least about 20 A.
degree.
; but is preferably no greater than about 500 A.
degree.
, more preferably no greater than about 200 A.
degree.
.
The particles are preferably used in an amount sufficient to provide an optimum catalytic effect under the operating conditions of the electrochemical device in which they are employed.
Relative to the amount of binder, however, the particles are preferably present in the ink in an amount, based on the weight of the catalytic particle, including its support, if any, sufficient to provide a weight ratio of component (a):component (c) of at least about 2:1, but preferably no more than about 5:1.
Suitable organic compounds include organic compounds having a pKa (the negative logarithm (to the base 10) of the equilibrium constant, K, for the reaction between the compound and water) of at least about 18 and a basicity parameter, .
beta.
, of less than 0.
66.
Preferably, the pKa is at least about 25.
Preferably, .
beta.
is less than about 0.
48, and is more preferably less than about 0.
40.
The basicity parameter for a number of organic compounds, as well as reference procedures for its determination, are described in Kamlet et al
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Nonmetallic Processes 
