Oronzio Denora Impianti Elettrochimici S.p.a.

Diamond Shamrock Technologies S.a.

Other

De Nora Permelec S.p.a.

Oronzio De Nora Impianti Electtrochimici S.p.a.

Oronzio Denora S.a.

S.e.r.e. S.r.l.

Oronzio De Nora Implanti Elettrochimici S.p.a.

Electronor Corporation

Oronzio Denora Technologies, Inc.

Oronzio De Nora Impianti Elettrochimici

Oronzio De Nora

Vittorio De Nora

Antonio Nidola

Placido M Spaziante

Luigi Giuffre

Giovanni Modica

Giuseppe Bianchi

Carlo Traini

Gian N Martelli

Ulderico Nevosi

Giovanni Meneghini

Richard Eric Loftfield

Renato Schira

James W Bess, Sr

Vittorio DeNora

Giovanni Trisoglio

A process for the electrolytic recovery of metals from solutions containing metal ions and fluorides and/or anionic flurocomplexes in diaphragmless cells wherein the deposition of the metals at the cathodes and the oxygen evolution at the anodes is effected, the improvement comprising the use of insoluble anodes made of sintered powders of doped tin dioxide optionally provided with coating of zirconyl phosphate and metal oxides which prevents the deposition of metal oxides on the anode surface and catalyze the oxygen evolution reaction.

Process for the electrolytic deposition of metals

The present invention relates to metal anodes for oxygen evolution from solutions containing fluorides or artionic fluorocomplexes such as tetrafluoroborates and hexafluorosilicates, the anodes having a metal substrate or matrix selected in the group comprising nickel-copper alloys with a copper content in the range of 2.5 and 30% by weight, tungsten or tantalum, niobium or titanium, combinations thereof or alloys of the same with palladium, nickel or yttrium. The anodes further comprise electrocatalytic compounds for oxygen evolution dispersed in the metal matrix. In the case of nickel- copper alloys, useful electrocatalytic compounds are cerium or tin dioxides, with suitable additives, while for tungsten, cobalt added with nickel, iron, copper or palladium may be used. The same electrocatalytic compounds may be advantageously applied to said metal substrate or matrix in the form of a coating using the conventional technique of thermal decomposition of paints containing suitable precursors or by thermal deposition such as plasma-spray.

Metal anodes for electrolytic acid solutions containing fluorides or

In a process for the electrolysis of alkali metal chloride conducted in a cell comprising a porous, gas and liquid permeable anode and a porous, gas and liquid permeable cathode separated by an ion exchange polymeric membrane impervious to the hydrodynamic flow, wherein the electrodes are in contact or in any way close to the membrane surface in order to reduce the interelectrodic gap, the insertion of a thin porous sheet, fluid permeable and highly hydrophilic, between the membrane and the cathode surfaces, allows for the considerable reduction of the cell voltage.

Membrane cell for the electrolysis of alkali metal chloride and process

An anode comprising an electroconductive substrate, whose external surface at least is selected from the group consisting of vanadium, niobium, tantalum and tungsten, alloys of said metals with each other and alloys of said metals with at least one metal selected from the group consisting of metals of groups IIIB and IV of the Periodic Table, lanthanides, actinides, the external surface having a corrosion resistant electrocatalytic coating of at least one member of the group consisting of noble metals and alloys thereof, noble metal oxides and non-noble metal oxieds, characterized in that the coating also contains at least one compound of an element selected from the group consisting of arsenic, antimony, bismuth, tin, for metal recovery from acid solutions based on fluodide-containing complex anions and an electrochemical cell.

Permanent anode

A cell is provided having an anode and cathode separated by an ion permeable membrane or diaphragm wherein an electrode layer is bonded to or otherwise embedded in on at least one and usually to both sides of the membrane. Polarity is imparted to a bonded or embedded electrode by pressing a crinkled resiliently compressible fabric against the membrane carrying the electrode layer. This fabric is substantially coextensive with the electrode layer and is constructed so that when compressed it exerts a substantially uniform elastic reaction pressure against the membrane carrying the electrode layer or a pliable foraminous sheet, i.e. screen, interposed between the membrane carrying the electrode layer and the resiliently compressible fabric. The resiliently compressible fabric has the ability of also transmitting pressure laterally so that pressure applied may distribute across the entire area of the layer and tendency to have local areas of too low of too high pressure is minimized or reduced. Chlorine or other halogen is produced by feeding an aqueous alkali metal halide or aqueous hydrogen halide to the anode chamber. Alkali is produced in the cathode chamber and withdrawn.

Electrolysis method of electrolyzing halides

Monopolar and bipolar electrolyzer and electrodic structures thereof

Halogen is produced by electrolyzing an aqueous halide in a specially designed cell. The cell comprises an anolyte chamber and a catholyte chamber separated by a permeable membrane or diaphragm, notably an ion exchange (generally cation exchange) polymer. At least one electrode comprises at least two sections. One section comprises a gas and electrolyte permeable layer, sheet or mat having a catalytic surface, i.e. one having a low overvoltage, (low hydrogen overvoltage if the cathode and low halogen overvoltage if the anode). This layer is spaced from the membrane by a second portion comprising an electroconductive resiliently compressible layer or mat, which is in contact with the membrane on one side thereof, the other side thereof being in contact with the main cathode. This second or spacer section advantageously has an electrode surface having a higher overvoltage than the first electrode surface. Preferably the cathode has the above construction. Upon electrolysis of alkali metal chloride or other halide in such a cell and with a cathode of the type described above, a low voltage is obtained even at high current densities and the cathode efficiency is high.

Electrolysis cell and method of generating halogen

Anodes made of lead or lead alloys, used for the evolution of oxygen from sulphuric acid solutions, particularly in metal electrowinning processes, are made more catalytic by treating them in an oxidizing bath of hydrated molten salts, in particular comprising highly oxidizing persalts or nitrates, of cobalt, iron and nickel. After treatment, the anodes exhibit an extraordinary low oxygen overvoltage and allow a considerable saving of energy in comparison with untreated anodes.

Low oxygen overvoltage lead anodes

An advantageous anodic structure, particularly useful for cathodic protection of metal structures having a large linear extension, is made of an insulated power cable having suitable terminal at least at one end for the electrical connection to the positive pole of the electrical source and of a series of anodic segments distributed over the length of the power cable, coaxial with the cable itself and electrically connected through a leak-proof connection with the conductive core of the insulated power cable without interruption of the core continuity.

Method of making electrical connection to an anode

Electrolysis cell

Anodic structure for cathodic protection

Halogen is produced by electrolyzing an aqueous halide in a specially designed cell. The cell comprises an anolyte chamber and a catholyte chamber separated by a permeable membrane or diaphragm, notably an ion exchange (generally cation exchange) polymer. At least one electrode comprises at least two sections. One section comprises a gas and electrolyte permeable layer, sheet or mat having a catalytic surface, i.e. one having a low overvoltage, (low hydrogen overvoltage if the cathode and low halogen overvoltage if the anode). This layer is spaced from the membrane by a second section comprising a thin intermediate electroconductive layer, screen or coating which is in contact with the membrane on one side thereof, the other side thereof being in contact with the main cathode. This second or spacer section advantageously has an electrode surface having a higher overvoltage than the first electrode surface. Preferably the cathode has the above construction. Upon electrolysis of alkali metal chloride or other halide in such a cell and with a cathode of the type described above, a low voltage is obtained even at high current densities and the cathode efficiency is high. The spacer may be in the form of a thin porous coating of metal or the like bonded to or in close contact with the membrane or it may be in the form of a gas and electrolyte permeable screen interposed between the membrane and the lower overvoltage section.

An electrolysis cell comprising a housing containing a plurality of alternating anode units and cathode units and an ion permeable membrane sheet disposed therebetween and having bonded to opposite sides of the membrane sheet a porous anode and a porous cathode, said cathode units comprising a pair of spaced foraminous electrical current cathode distributors of the same polarity forming a space for catholyte therebetween and means for flowing aqueous electrolyte through the catholyte space of the cathode unit and means for removing electrolysis products, the anode units comprising a pair of spaced foraminous electrical current anode distributors forming a space for anolyte therebetween, means for flowing aqueous halide solution through the said anolyte space and means for removing electrolysis products therefrom and means for uniformly compressing the units and membranes together whereby the current distributors are in firm electrical contact with their respective electrodes and to a novel method of generating halogens by electrolysis of aqueous halide solutions.

Novel electrolysis cell

A cell is provided having an anode and cathode separated by an ion permeable membrane or diaphragm wherein an electrode layer is bonded to or otherwise embedded in on at least one and usually to both sides of the membrane. Polarity is imparted to a bonded or embedded electrode by pressing a crinkled resiliently compressible fabric against the membrane carrying the electrode layer. This fabric is substantially coextensive with the electrode layer and is constructed so that when compressed it exerts a substantially uniform elastic reaction pressure against the membrane carrying the electrode layer or a pliable foraminous sheet, i.e. screen, interposed between the membrane carrying the electrode layer and the resiliently compressible fabric. The resiliently compressible fabric has the ability of also transmitting pressure laterally so that pressure applied may distribute across the entire area of the layer and tendency to have local areas of too low or too high pressure is minimized or reduced. Chlorine or other halogen is produced by feeding an aqueous alkali metal halide or aqueous hydrogen halide to the anode chamber. Alkali is produced in the cathode chamber and withdrawn.

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Milan, Italy

Oronzio De Nora