Abstract: Provided is a gas diffusion electrode equipped ion exchange membrane electrolyzer including an anode, an ion exchange membrane, and a cathode chamber in which a gas diffusion electrode is disposed, wherein the ion exchange membrane and a cathode chamber inner space in which the gas diffusion electrode is disposed are separated by a liquid retaining member, the outer periphery of the liquid retaining member is held in a void formed in a gasket or a cathode chamber frame constituting the cathode chamber, or the outer periphery and the end face of the outer periphery of the liquid retaining member are sealed, or the outer periphery of the liquid retaining member is joined to and integrated with the gasket.

Abstract: Provided is a gas diffusion electrode equipped ion exchange membrane electrolyzer including an anode, an ion exchange membrane, and a cathode chamber in which a gas diffusion electrode is disposed, wherein the ion exchange membrane and a cathode chamber inner space in which the gas diffusion electrode is disposed are separated by a liquid retaining member, the outer periphery of the liquid retaining member is held in a void formed in a gasket or a cathode chamber frame constituting the cathode chamber, or the outer periphery and the end face of the outer periphery of the liquid retaining member are sealed, or the outer periphery of the liquid retaining member is joined to and integrated with the gasket.

Abstract: An electrode for electrochemical processes for gas production, which in the installed state is located parallel and opposite to an ion exchange membrane and consists of a multitude of horizontal lamellar elements which are structured and three-dimensionally shaped and are in contact with only one surface with the membrane, wherein the lamellar elements have grooves and holes, the major part of the holes being placed in the grooves and the surfaces of such holes or part thereof are located in the grooves or extend into the grooves whereby the holes are ideally placed in the contact area of the respective lamellar element with the membrane.

Abstract: Chlorine is produced by electrolysis of aqueous HCl, in a membrane electrolyzer, using cathodic mediators such as Fe(III) and/or Cu(II) chlorides and a non-catalysed 3-dimensional cathode, with the real surface area at least ten times higher than its projected area. The HCl electrolysis section is combined with an oxidizer for regeneration of the mediator, product water removal step and optional HCl recovery step. Under optimized conditions chlorine can be produced at very high current densities of 30 kA/m2, without initiating undesired H2 evolution reaction at the cathode.

Abstract: A rhodium sulfide electrocatalyst formed by heating an aqueous solution of rhodium salt until a steady state distribution of isomers is obtained and then sparging hydrogen sulfide into the solution to form the rhodium sulfide and a membrane electrode assembly with the said electrode and a process for electrolyzing hydrochloric acid.

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: A gas diffusion electrode comprising an electrically conductive web provided on at least one side thereof with a coating containing a rhodium--rhodium oxide catalyst on a carbon black support and a method for the preparation of the rhodium--rhodium oxide catalyst.

Abstract: The improved method for the production of chlorine from aqueous solutions of hydrochloric acid in a membrane electrolysis cell comprises a cathode compartment equipped with a gas diffusion cathode fed with air or enriched air or oxygen and an anodic compartment with an anode provided with an electrocatalytic coating for chlorine evolution. Said anode compartment is fed with an aqueous solution of hydrochloric acid having a maximum concentration of 20% and a maximum temperature of 60.degree. C., and containing an oxidizing compound having a redox potential of at least 0 Volts NHE and preferably 0.3-0.6 Volts NHE. A suitable oxidizing compound is trivalent iron in concentrations comprised in the range of 100-10,000 ppm. Both the anodic and cathodic compartment of the cell and their internal structures are made of titanium or alloys thereof, such as 0.2%. titanium-palladium.

Abstract: The invention relates to a process for electrochemically converting anhydrous hydrogen halide, such as hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, to essentially dry halogen gas, such as chlorine, fluorine, bromine and iodine gas, respectively. In a preferred embodiment, the present invention relates to a process for electrochemically converting anhydrous hydrogen chloride to essentially dry chlorine gas. This process allows the production of high-purity chlorine gas. In this process, molecules of essentially anhydrous hydrogen chloride are transported through an inlet of an electrochemical cell. The molecules of the essentially anhydrous hydrogen chloride are oxidized at the anode of the cell to produce essentially dry chlorine gas and protons, which are transported through the membrane of the cell. The transported protons are reduced at the cathode to form either hydrogen gas or water.