Exxon Research and Engineering Company

John S Batzold

Yen-Chi Pan

Alvin Skopp

George Ciprios

James E Hoffmann

Judith C Savas

A porous gas fed electrode adapted to operate in a large capacity cell with a stable three phase interface in the electrode thereby avoiding the problems of gas percolation can be readily achieved in a simple and inexpensive manner by applying a porous hydrophilic layer on the surface of the electrode which is in contact with the aqueous electrolyte. Due to the high capillary pressure exhibited by liquids in hydrophilic pores, very high gas pressures are required to force the gas through the structure and the loss of gas into the electrolyte is thereby eliminated. In addition, a gas pressure in the gas compartment of the electrochemical cell employing such an electrode can be raised to balance the electrolyte pressure at the bottom of the electrode thereby effectively preventing electrolyte seepage into the gas compartment. Thus, in its simplest sense, the present invention comprises a porous gas fed electrode structure having a hydrophilic layer on the surface of the electrode which contacts liquid electrolyte.

Gas percolation barrier for gas fed electrode

The present invention encompasses the use of a specific fuel fed electrode in depositing metals from solutions thereof and in the absence of an external applied potential. Basically as shown in FIG. 1, the electrode comprises an electrically conductive porous substrate 3 bearing on one surface thereof a fuel activating catalyst 4. The porosity of the substrate is sufficient that the current density at surface 2 of the substrate 3 opposite the catalyst 4 will assure substantially complete depletion of metal ions very near the surface of the porous substrate, whereby the catalyst surface and the pores remain substantially free of deposited metal.

Spontaneous deposition of metals using fuel fed catalytic electrode

The present invention is predicated upon the discovery that in the electrowinning of copper from solutions thereof, a hydrogen fed porous catalytic anode can be caused to operate under such conditions of constant current flow whereby a dynamic equilibrium will be imposed upon the hydrogen fed anode so that the anode will behave as a normal copper anode in a refining mode. This is particularly true when such a hydrogen fed anode is deactivated by copper buildup on the surface of the electrode.

Energy efficient self-regulating process for winning copper from aqueous

Hydrogen is produced in a cyclic metals oxidation/carbon reduction process. In particular, elemental iron or cobalt is oxidized in an aqueous solution of an alkali metal hydroxide with the simultaneous generation of hydrogen. The iron or cobalt oxidation products of the reaction are thereafter reduced to elemental iron or cobalt by contact with a carbonaceous reducing agent at elevated temperatures and the reduced material recycled for reoxidation. In an alternate operation, hydrogen is produced in a cyclic electrolytic/carbon reduction process wherein elemental iron or cobalt is electrolytically converted to corresponding oxidation products with the simultaneous generation of hydrogen. The electrolytic cell used in this process comprises a cathode, a magnetic anode that is adapted to attract and retain iron and/or cobalt particles and an aqueous electrolyte. In the electrolytic cell, hydrogen is produced at the cathode and metal particles contained on the magnetic electrode are oxidized to a non-ferromagnetic specie, such as ferrous hydroxide. The non-ferromagnetic species are recovered from the electrolytic cell and thereafter reconverted to particulate elemental iron and/or cobalt by treating the material with a carbonaceous reductant at an elevated temperature.

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Union, NJ, United States of America

John S Batzold