Process for making catalytically active Raney nickel electrodes
AssigneeE. I. Du Pont de Nemours and Company
InventorChristopher R. S. Needes
Life of this patent
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Abstract
A process for making an electrode having a Raney nickel surface layer of thickness greater than 75 microns and an average porosity of at least 11%, comprising interdiffusing aluminum and nickel on a conductive metal core at a temperature of at least 660.degree. C. to form a nickel-aluminum alloy layer on the core from which layer aluminum is selectively dissolved. When used as a cathode in an electrolytic cell for producing hydrogen, chlorine and caustic from brine, the electrode exhibits low hydrogen overvoltage.
Claims14
In a process for electrolyzing brine into chlorine, hydrogen and caustic in an electrolytic cell using a hydrogen-evolution cathode with an active porous nickel surface, the improvement comprising employing as the cathode an electrode having a porous Raney nickel layer of between 100 and 400 microns, an average porosity of at least 11%, and an average agglomerate size of at least 35 microns, thereby lowering hydrogen overvoltage.
In a process for preparing an electrode having a continuous surface layer of active porous nickel in electrical contact with a conductive metal core by interdiffusing a nickel-aluminum alloy layer on the core and then selectively leaching aluminum from the interdiffused layer, the improvement comprising:
- providing the core with a nickel-bearing surface layer having a thickness of at least 100 microns and containing at least 15 percent by weight of nickel;
- interdiffusing aluminum and at least a portion of the nickel in the surface layer of the core at a temperature of at least 660.degree. C. for a time sufficient to provide the interdiffused nickel-aluminum alloy layer with a thickness of at least 85 microns;
- and
- selectively leaching, with an aqueous base, sufficient aluminum from the interdiffused alloy layer to provide an electrode having a continuous surface layer of active porous Raney nickel in electrical contact with, and metallurgically bonded to, the conductive metal core, said Raney nickel layer having a thickness of between 100 and 400 microns, an average porosity of at least 11%, and an averge agglomerate size of at least 35 microns.
Dependencies are inferred from the claim text.