Abstract: A transition metal electrocatalyst surface (e.g. a porous surface of finely divided Group VIII or Group I-B metal with an attached current collector) is modified by a sulfur treatment, using an oxidized sulfur species of average sulfur oxidation state of about 4 or less, e.g. SO.sub.2 dissolved in aqueous acid. Treatment of the transition metal with SO.sub.2 or the like typically provides up to 100% coverage of the surface electrocatalyst sites with chemisorbed sulfur-containing species and perhaps subsurface effects as well, but washing or other non-electrochemical techniques can remove 5-90% (e.g. 25-70%) of the chemisorbed SO.sub.2 or the like from the surface, leaving substantially only a very strongly bound form of the sulfur-containing species. The strongly bound sulfur-containing species can then be reduced to form a highly beneficial, selectively-improving pattern of sites containing reduced -S (e.g. sulfur or sulfide) on the electrocatalyst surface.

Abstract: A transition metal electrocatalyst surface (e.g. a porous surface of finely divided Group VIII or Group I-B metal with an attached current collector) is modified by a sulfur treatment, using an oxidized sulfur species of average sulfur oxidation state of about 4 or less, e.g. SO.sub.2 dissolved in aqueous acid. Treatment of the transition metal with SO.sub.2 or the like typically provides up to 100% coverage of the surface electrocatalyst sites with chemisorbed sulfur-containing species and perhaps subsurface effects as well, but washing or other non-electrochemical techniques can remove 5-90% (e.g. 25-70%) of the chemisorbed SO.sub.2 or the like from the surface, leaving substantially only a very strongly bound form of the sulfur-containing species. The strongly bound sulfur-containing species can then be reduced to form a highly beneficial, selectivity-improving pattern of sites containing reduced --S (e.g. sulfur or sulfide) on the electrocatalyst surface.

Abstract: A method for reclaiming gold in metallic form from gold-containing scrap, including gold-containing base metal alloys and articles in which base metals are at least partially covered with a layer of gold. The method includes the steps of exposing the gold-containing scrap under an inert atmosphere to a leaching solution. The leaching solution has dissolved therein an oxidizing agent including metal ions capable of assuming at least two oxidation states, a portion of the metal ions being in the higher of the two oxidation states. The leaching solution also contains a complexing agent including halide ions in aqueous solution. By so exposing the gold-containing scrap to the leaching solution, base metal contained therein is dissolved to leave a solid metallic residue enriched in gold. The solid metallic residue then is collected mechanically.

Abstract: Nitrogen oxides, such as nitric oxide with hydrogen separated by acid electrolytes, are reacted at porous catalytic electrodes in a configuration to generate electrical energy and selectively reduce the nitric oxide to ammonia, hydroxylamine and other products. Product distribution and reaction rate can be controlled with electrocatalyst, external load and other parameters. The electrogenerative process is applied to the reduction of other gases.

Abstract: In the disclosed process, the winning of noble or relatively electronegative metals (e.g. Au, Ag, Cu, Ni, etc.) from substantially aqueous solutions containing ions of the metal through the use of relatively electropositive precipitant metals (e.g. Fe, Zn, Al, etc.) is carried out along with recovery or utilization of some of the energy which can be produced by chemical or electrochemical action. In this process, an electrochemical primary cell-like arrangement with a one-fluid or two-fluid electrolyte (wherein the precipitant metal can be an anode) can also provide improvements in the character (orderliness, efficiency, purity of product, etc.) and control of the cementation reactions. For example, bright (high purity) copper can be obtained in a cathode compartment in a two-fluid cell using a scrap iron anode, a pregnant hydrometallurgical cuprous or cupric leach solution as the catholyte, and an external circuit connecting the cathode to the anode.

Abstract: In the disclosed process, relatively pure copper is efficiently recovered from metallic alloy, scrap or cement, by electrochemical dissolution and deposition (as the relatively pure copper) under special conditions. In a halide solution, in a cell free from oxygen, the contaminated or alloyed copper is transferred from the impure state and separated by means of a substantially one electron process for the copper involved. The process can be operated in a one-fluid, or a two-fluid cell with diaphragm, depending on the composition of alloy or metal to be purified. For instance, in the case of copper-zinc alloys or mixtures, the copper is readily recovered in a one-fluid cell by suitable arrangement. Particularly with more complex alloys or mixtures, however, it can be advantageous to use a two-fluid cell and an intermediate purification stage between direct dissolution and electrodeposition. Concomitant metals may be recovered in either the metallic state or as chemical compounds.