Abstract: The invention relates to an amalgam decomposer for mercury cathode chlor-alkali cells. The amalgam decomposer of the invention contains a filling of carbon steel rings whose external surface is provided with a catalytic coating for amalgam decomposition consisting of one or more electrically conductive metals carbides. The internal surface of the rings is free of catalytic coating and wettable by the amalgam, while the external carbide catalytic coating is not wettable by the amalgam thereby favouring hydrogen evolution.

Abstract: The invention relates to a device for breaking the electrical continuity of the stream of caustic soda produced in mercury-cathode chlor-alkali plants.

Abstract: There is disclosed an inlet and outlet end-box design for mercury cathode chlor-alkali electrolysis cells of extended lifetime, comprising a composite mechanical structure consisting of a carbon steel bottom entirely supporting the mechanical solicitations, a plastic cover, and a hydraulic head device for washing the mercury and the amalgam. The device is partially extractable thereby allowing the withdrawal of foreign materials accumulated during operation with no need for opening the end-boxes.

Abstract: A system for the electrolytic production of sodium chlorate having a sodium chloride brine buffered with phosphate and having a reduced or zero chromium content is disclosed. The system comprises electrolytic cells of the undivided type with intercalated cathodes and anodes. The cathodes can comprise steel perforated sheets activated with a Fe—Mo alloy coating.

Abstract: There is disclosed a process of electrochemical reduction, optionally coupled to a final stage of chemical finishing, of solutions containing hexavalent chromium. The electrochemical reduction is carried out making use of a cell of cylindrical geometry with tangential solution inlet and outlet, which establishes and maintains a spiral flow across the whole electrolysis bulk, achieving effective mass transport conditions.

Abstract: There is disclosed a cathodic protection system of reinforced concrete structures with discrete anodes obtained starting from a corrugated planar substrate welded to a longitudinal current collector. The anodes of the invention are particularly suitable for being installed rolled in cylinders, with their axis parallel to the current collectors, positioned inside holes made in the concrete of the structure to be protected.

Abstract: The invention concerns a proton exchange membrane comprising a perfluorosulfonic acid having silica particles embedded therein in a concentration by weight comprised between 0.01 and 50% by weight and dimensions comprised between 0.001 and 10 micrometers, characterized in that said membrane comprises both an amorphous and a crystalline phase and the ratio thereof is adjusted by means of a controlled thermal treatment at a temperature higher than the glass transition temperature, controlled by an X-ray spectrometer. The invention further concerns an electrochemical cell using said membrane, in particular a fuel cell and the method of operating the same.

Abstract: This invention pertains to improved formulations of platinum-molybdenum alloys for use as anode catalysts. These electrocatalysts find utility as a constituent of gas diffusion electrodes for use in fuel cells that operate at less than 180° C. or in applications whereupon hydrogen is oxidized in the presence of carbon monoxide or other platinum inhibiting substances. The new formulations derive unexpected activity through creating highly dispersed alloy particles of up to approximately 300 Å on carbon supports. The desired activity is achieved by carefully controlling the platinum to molybdenum ratio during preparation and judiciously selecting a proper loading of alloy on the carbon support.

Abstract: The invention relates to a novel rhodium sulfide catalyst for the reduction of oxygen in industrial electrolyzers. The catalyst is highly resistant towards corrosion and poisoning by organic species, thus resulting particularly suitable for use in aqueous hydrochloric acid electrolysis, when technical grade acid containing organic contaminants is employed.

Abstract: The invention concerns a diaphragm chlor-alkali electrolysis cell comprising a cover, a conductive base for supporting the anodes and a cathode in the form of a box provided with internal wall, external wall and tubular fingers made of a mesh or perforated sheet covered with a porous diaphragm. One or more copper sheets for electric current distribution are fixed to the cathode external walls. The connection between the copper sheets and the cathode external walls is made by means of bolts with the interposition of a conductive and deformable element provided with residual elasticity under compression. The weldings for the assembling of the cathode walls are free from internal stresses.

Abstract: The invention describes a method for applying an electrocatalytic or a protective coating to a metal substrate or repairing a damaged area of the same, consisting in a thermal treatment of a precursor of said catalytic coating by means of a hot air jet from a blower. The temperature of the substrate is locally controlled by means of surface temperature sensors or by an infrared measuring system. The metal substrate may be an exhausted electrode structure, in which case the reactivation is easily carried out at the plant site without any need of sending the structure to the producer. The method of the invention is particularly useful for reactivating anodes for oxygen evolution as it permits to avoid the risky procedure of detaching the anode from the current conductor.

Abstract: The present invention discloses a new design of elements for ion exchange membrane electrolyzers for the electrolysis of brine to produce chlorine, hydrogen and caustic soda. This new design solves the problems affecting prior art, by both minimizing the electrolyte concentration and temperature gradients, and the pressure fluctuation resorting to components which are easy to be installed and may be obtained through automated production cycles.

Abstract: It is described a novel type of electrode suitable for use as an anode for oxygen evolution from electrolytes containing sulphuric acid, or sulphates, in the presence of manganese, in electrometallurgical processes for the production of zinc, copper, nickel and cobalt and galvanic processes for the deposition of chromium, nickel and noble metals. The anode of the invention comprises a titanium substrate provided with an electrocatalytic coating for oxygen evolution made of iridium and bismuth oxides. In an alternative embodiment of the invention the coating comprises doping agents selected from the groups IV A, V A and V B, particularly tin and/or antimony.

Abstract: This invention pertains to improved formulations of platinum--molybdenum alloys for use as anode catalysts. These electrocatalysts find utility as a constituent of gas diffusion electrodes for use in fuel cells that operate at less than 180.degree. C. or in applications whereupon hydrogen is oxidized in the presence of carbon monoxide or other platinum inhibiting substances. The new formulations derive unexpected activity through creating highly dispersed alloy particles of up to approximately 300 .ANG. on carbon supports. The desired activity is achieved by carefully controlling the platinum to molybdenum ratio during preparation and judiciously selecting a proper loading of alloy on the carbon support.

Abstract: A proton exchange membrane comprising a perfluorosulfonic acid having silica particles embedded therein at a concentration of 0.01 to 5% by weight, said particles having a dimension of 0.001 to 10 micrometers, the membrane having a crystalline phase and an amorphous phase in a ratio adjusted by controlled thermal treatment at a temperature higher than the glass transition temperature, an electrochemical cell containing said membrane and a process for oxidizing a fuel in said electrochemical cell.

Abstract: The invention relates to a novel rhodium sulfide catalyst for the reduction of oxygen in industrial electrolyzers. The catalyst is highly resistant towards corrosion and poisoning by organic species, thus resulting particularly suitable for use in aqueous hydrochloric acid electrolysis, when technical grade acid containing organic contaminants is employed.

Abstract: Gas Diffusion Electrodes (GDES) play a pivotal role in clean energy production as well as in electrochemical processes and sensors. These gas-consuming electrodes are typically designed for liquid electrolyte systems such as phosphoric acid and alkaline fuel cells, and are commercially manufactured by hand or in a batch process. However, GDEs using the new electrolytes such as conductive polymer membranes demand improved electrode structures.This invention pertains to GDEs and gas diffusion media with new structures for systems using membrane electrode assemblies (MEAs), and automated methods of manufacture that lend themselves to continuous mass production Unexpected improvements in gas and vapor transport through the electrode are realized by incorporating a new dispersion process in the construction, reformulating the applied mix with solution additives, and creating a novel coating structure on a conductive web.

Abstract: A new electrocatalytic coating to be applied onto a titanium matrix, suitable for oxygen evolution from acid electrolytes containing manganese and fluorides, comprising:a) an external coating for oxygen evolution at controlled potential, immune to manganese electrochemical precipitation and capable of promoting the spontaneous removal of the same during operation, consisting of ruthenium and iridium as the major components (60-85%), tin and cobalt (2-10%) and titanium and tantalum at intermediate concentrations with respect to the previous groups of components.b) an optional interlayer acting as an electroconductive system and protecting the titanium matrix against corrosion caused by fluorides, made of titanium and tantalum as the major components (<95%) and iridium (>5%) as the minor component.At least part of the above elements are in the form of oxides.

Abstract: The invention concerns a diaphragm chlor-alkali electrolysis cell comprising a cover, a conductive base for supporting the anodes and a cathode in the form of a box provided with internal wall, external wall and tubular fingers made of a mesh or perforated sheet covered with a porous diaphragm. One or more copper sheets for electric current distribution are fixed to the cathode external walls. The connection between the copper sheets and the cathode external walls is made by means of bolts with the interposition of a conductive and deformable element provided with residual elasticity under compression. The weldings for the assembling of the cathode walls are free from internal stresses.

Abstract: The invention is to a dual beam process for providing an ion-conducting membrane with a thin metal or metal-oxide film. The process includes the cleaning of a membrane surface with a low energy electron beam followed by the deposition of the metal or metal-oxide film by a high energy electron beam of ions.