Abstract: An electrolysis cell for chlor-alkali electrolysis, including an anode chamber for accommodating an anode and for accommodating an electrolytic solution, wherein the anode chamber includes a circulation structure for improving circulation of the electrolytic solution and at least one baffle plate for improving horizontal homogeneity of the electrolytic solution.

Abstract: Demand-based closed-loop control is used in an electrochemical plant that has modules and a control unit, with each module being individually controlled by the control unit and supplied with a module-specific electric operating current. For each module to generate a separate product flow, product flows of the individual modules, connected in parallel, are merged to form a total product flow. When a start condition occurs, the control unit records a current total product flow demand, records a current efficiency of the modules based on a ratio of respective operating current and product flow, determines operationally ready modules, determines module-specific target operating currents for the operationally ready modules to cover the demand from a range of permissible module-specific target operating currents based on the efficiency of the modules and the demand, and sets the operating currents of the operationally ready modules to the determined module-specific target operating currents.

Abstract: An electrolysis device for the electrolytic treatment of liquids has an anode chamber and a cathode chamber which are separated from one another via an ion exchange membrane. The chambers are provided with an inlet opening and an outlet opening for the flowing electrolyte, each with one electrode. The inner space of the anode chamber and/or of the cathode chamber are/is subdivided by webs or ribs extending transversely with respect to the electrodes. The webs or ribs are provided at least regionally with holes or cut outs. The webs or ribs include at least one lower region free of holes or cut outs. The electrolysis device provides sufficient mixing in the upper foam phase in the longitudinal direction and also at the same time the airlift pump effect is maintained by way of ascending gas bubbles in the lower region.

Abstract: An electrolysis device for the electrolytic treatment of liquids has an anode chamber and a cathode chamber which are separated from one another via an ion exchange membrane. The chambers are provided with an inlet opening and an outlet opening for the flowing electrolyte, each with one electrode. The inner space of the anode chamber and/or of the cathode chamber are/is subdivided by webs or ribs extending transversely with respect to the electrodes. The webs or ribs are provided at least regionally with holes or cut outs. The webs or ribs include at least one lower region free of holes or cut outs. The electrolysis device provides sufficient mixing in the upper foam phase in the longitudinal direction and also at the same time the airlift pump effect is maintained by way of ascending gas bubbles in the lower region.

Abstract: The present invention concerns a method of retrofitting of a membrane electrolysis cell, wherein a rigid cathode is shaped by plastic deformation of the regions in correspondence of cathodic supports; a pre-shaped conductive elastic element having compressed regions in correspondence of said cathodic supports is overlaid onto said rigid cathode; a flexible planar cathode provided with a catalytic coating is overlaid onto said conductive elastic element. The invention also concerns a correspondingly retrofitted electrolysis cell.

Abstract: An electrolysis cell provided with a separator, suitable for chlor-alkali electrolysis, has a planar flexible cathode kept in contact with the separator by an elastic conductive element pressed by a current distributor and an anode consisting of a punched sheet or mesh supporting the separator suitable for being individually pre-assembled and used as elementary unit of a modular arrangement to form an electrolyzer whose terminal cells only are connected to the electric power supply; the electrical continuity between adjacent cells being assured by conductive contact strips secured to the external anodic walls of the shells delimiting each cell with the stiffness of the cathode current distributor and of the anodic structure and the elasticity of the conductive element cooperate in maintaining a uniform cathode to separator contact with a homogeneous pressure distribution meanwhile ensuring a suitable mechanical load on the contact strips.

Abstract: An electrolysis cell provided with a separator, suitable for chlor-alkali electrolysis, has a planar flexible cathode kept in contact with the separator by an elastic conductive element pressed by a current distributor and an anode consisting of a punched sheet or mesh supporting the separator suitable for being individually pre-assembled and used as elementary unit of a modular arrangement to form an electrolyser whose terminal cells only are connected to the electric power supply; the electrical continuity between adjacent cells being assured by conductive contact strips secured to the external anodic walls of the shells delimiting each cell with the stiffness of the cathode current distributor and of the anodic structure and the elasticity of the conductive element cooperate in maintaining a uniform cathode to separator contact with a homogeneous pressure distribution meanwhile ensuring a suitable mechanical load on the contact strips.

Abstract: The invention relates to an anode comprising a titanium alloy substrate coated with noble metals by thermal decomposition of precursors thereof. The alloy of the substrate includes elements which can be oxidised during the thermal decomposition step, allowing electrical energy savings and a prolonged duration in industrial electrolytic processes. The anode of the invention is suitable for chlor-alkali electrolysis, allowing to produce chlorine with a lower oxygen content and a lower energy consumption than the anodes of the prior art.

Abstract: The invention relates to a gas-diffusion electrode for chlor-alkali electrolysis cells integrated in a percolator of plastic porous material suitable for being vertically crossed by a downward flow of electrolyte. The electrode comprises a catalytic composition based on silver and/or nickel mixed to a polymeric binder, directly supported on the percolator without any interposed reticulated metal current collector.

Abstract: It is described a bipolar plate consisting of a single wall and a perimetrical sealing frame obtained by folding and provided with a planar abutment surface for the frame-to-wall welding. The wall is further provided with projections on one face thereof preferably obtained by moulding, and with supports on the other face consisting of sheet strips housed in the recesses formed by the concave part of the projections. The projections substantially extend along the entire length of the bipolar plate. The projections and supports are connected to electrodes or current distributors. The projections, the supports, the single wall and the perimetrical frame are made of the same metal or alloy. The electrode or current distributor supported by the projections, the same projections and the supports are welded together by a single pass of arc-welding or preferably laser-welding.

Abstract: A membrane electrolysis cell comprising an anodic compartment and a cathodic compartment is described, wherein at least one of the two compartments contains an electrode fed with gas and a porous planar element is interposed between the membrane and the gas-fed electrode. A flow of chemically aggressive electrolyte crosses the porous planar element downwards under the effect of the gravity force. The planar element consists in a plastic element withstanding the aggressive operative conditions: The use of perfluorinated plastics such as ECTFE, PTEFE, FEP, PFA is preferred, even though they are strongly hydrophobic. When the gas-fed electrode is a cathode and the gas contains oxygen, the gas crosses the cathodic compartment upwardly so as to minimize the risk of hydrogen build up. The cell equipped with the oxygen cathode is particularly advantageous for the sodium chloride electrolysis.

Abstract: The invention relates to an anode comprising a titanium alloy substrate coated with noble metals by thermal decomposition of precursors thereof. The alloy of the substrate includes elements which can be oxidised during the thermal decomposition step, allowing electrical energy savings and a prolonged duration in industrial electrolytic processes. The anode of the invention is suitable for chlor-alkali electrolysis, allowing to produce chlorine with a lower oxygen content and a lower energy consumption than the anodes of the prior art.

Abstract: An electrolysis cell comprising an anodic compartment and a cathodic compartment separated by an ion-exchange membrane, at least one of said compartments equipped with a gas-diffusion electrode having two major surfaces, the first major surface of said gas-diffusion electrode facing the membrane and being in contact with a planar porous element to be traversed by an electrode flow, the second major surface of said gas-diffusion electrode being in contact with a current distributor comprising a multiplicity of elastic conductive protrusions for compressing said gas-diffusion electrode against said planar porous element.

Abstract: The invention relates to a gas-diffusion electrode for chlor-alkali electrolysis cells integrated in a percolator of plastic porous material suitable for being vertically crossed by a downward flow of electrolyte. The electrode comprises a catalytic composition based on silver and/or nickel mixed to a polymeric binder, directly supported on the percolator without any interposed reticulated metal current collector.

Abstract: It is described a bipolar plate consisting of a single wall and a perimetrical sealing frame obtained by folding and provided with a planar abutment surface for the frame-to-wall welding. The wall is further provided with projections on one face thereof preferably obtained by moulding, and with supports on the other face consisting of sheet strips housed in the recesses formed by the concave part of the projections. The projections substantially extend along the entire length of the bipolar plate. The projections and supports are connected to electrodes or current distributors. The projections, the supports, the single wall and the perimetrical frame are made of the same metal or alloy. The electrode or current distributor supported by the projections, the same projections and the supports are welded together by a single pass of arc-welding or preferably laser-welding.

Abstract: An oxygen-depolarized cathode for aqueous hydrochloric acid electrolysis membrane cells is described, the cathode being in contact with the membrane and capable of preventing the release of hydrogen into oxygen even at the highest current densities. Hydrochloric acid may also be of technical grade with a concentration limited to 15%, whereas the operating temperature must not exceed 60° C. The cathode contains a mixture of rhodium sulphide and a metal of the platinum group applied in a single layer or alternatively applied separately in two distinct layers.

Abstract: A bipolar assembly for filter-press type electrolyzers is described comprising a single sheet, whose two faces work respectively as anodic and cathodic wall, characterised by a design of perimetral flanges which greatly simplifies its construction enhancing its reliability. The peripheral flanges are made of a first flange obtained by folding the peripheral portion of the single sheet and of a second flange formed by a rod or a tube with quadrangular section or, alternatively, the first and second flange are pre-formed by folding of adequate strips subsequently fixed to the single sheet. The electrolyser resulting from the assemblage of a multiplicity of assemblies of the invention is particularly suited to the process of electrolysis of hydrochloric acid solutions carried out with chlorine-evolving anodes and oxygen-consuming cathodes.

Abstract: A membrane electrolysis cell comprising an anodic compartment and a cathodic compartment is described, wherein at least one of the two compartments contains an electrode fed with gas and a porous planar element is interposed between the membrane and the gas-fed electrode. A flow of chemically aggressive electrolyte crosses the porous planar element downwards under the effect of the gravity force. The planar element consists in a plastic element withstanding the aggressive operative conditions: The use of perfluorinated plastics such as ECTFE, PTEFE, FEP, PFA is preferred, even though they are strongly hydrophobic. When the gas-fed electrode is a cathode and the gas contains oxygen, the gas crosses the cathodic compartment upwardly so as to minimise the risk of hydrogen build up. The cell equipped with the oxygen cathode is particularly advantageous for the sodium chloride electrolysis.

Abstract: A bipolar assembly for filter-press type electrolysers is described comprising a single sheet, whose two faces work respectively as anodic and cathodic wall, characterised by a design of perimetral flanges which greatly simplifies its construction enhancing its reliability. The peripheral flanges are made of a first flange obtained by folding the peripheral portion of the single sheet and of a second flange formed by a rod or a tube with quadrangular section or, alternatively, the first and second flange are pre-formed by folding of adequate strips subsequently fixed to the single sheet. The electrolyser resulting from the assemblage of a multiplicity of assemblies of the invention is particularly suited to the process of electrolysis of hydrochloric acid solutions carried out with chlorine-evolving anodes and oxygen-consuming cathodes.

Abstract: An oxygen-depolarised cathode for aqueous hydrchloric acid electrolysis membrane cells is described, the cathode being in contact with the membrane and capable of preventing the release of hydrogen into oxygen even at the highest current densities. Hydrochloric acid may also be of technical grade with a concentration limited to 15%, whereas the operating temperature must not exceed 60° C. The cathode contains a mixture of rhodium sulphide and a metal of the platinum group applied in a single layer or alternatively applied separately in two distinct layers.