Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/01—Products
  • C25B1/02—Hydrogen or oxygen
  • C25B1/04—Hydrogen or oxygen by electrolysis of water
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/50—Processes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B15/00—Operating or servicing cells
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B15/00—Operating or servicing cells
  • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B5/00—Electrogenerative processes, i.e. processes for producing compounds in which electricity is generated simultaneously
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
  • C25B9/70—Assemblies comprising two or more cells
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/06—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/06—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese
  • C25C1/08—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese of nickel or cobalt
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/06—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese
  • C25C1/10—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese of chromium or manganese
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/12—Electrolytic production, recovery or refining of metals by electrolysis of solutions of copper
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/14—Electrolytic production, recovery or refining of metals by electrolysis of solutions of tin
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/16—Electrolytic production, recovery or refining of metals by electrolysis of solutions of zinc, cadmium or mercury
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/20—Electrolytic production, recovery or refining of metals by electrolysis of solutions of noble metals
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/22—Electrolytic production, recovery or refining of metals by electrolysis of solutions of metals not provided for in groups C25C1/02 - C25C1/20
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the field of the invention is that of the electrochemical production of gaseous hydrogen under pressure.
• the invention relates to an electrochemical process for producing gaseous hydrogen by electrolysis and electrochemical conversion of H + ions to hydrogen gas, either by depolarization with production of electrical energy (battery), or by catalytic means, or by electrolysis.
• the invention also relates to a device for the implementation of such a process for producing hydrogen, and a kit comprising the device and all or part of consumables useful in said method.
• Hydrogen is the cleanest and most efficient fuel for producing energy both in a fuel cell and in an internal combustion engine.
• the storage of energy in the form of hydrogen under pressure is also particularly advantageous.
• Hydrogen is an invisible gas that is odorless and non-toxic. Its consumption in a fuel cell produces only electrical energy and water. In the same way, its combustion also leads to water and no harmful by-products.
• the most economical and therefore most widely used method of producing hydrogen is the reforming of natural gas to steam.
• hydrogen appears to be the most appropriate energy carrier to support the energy transition, in particular to allow clean mobility as well as energy storage.
• the conventional method is to compress the gas with a mechanical compressor; it is an expensive operation and requires many maintenance operations.
• patent application US20040211679A1 discloses a method of performing electrochemical compression at the outlet of the electrolyser, in a second apparatus. This technical proposal has the drawback of making the production process more complex, and therefore more expensive.
• a metal salt (zinc, nickel or manganese) is used in an electrolytic cell to decouple the electrolysis reaction from water in two steps.
• the method makes it possible to store electricity by depositing a metal on the cathode and releasing oxygen at the anode of the electrolytic cell.
• the electrolytic cell operates in battery mode, allowing the dissolution of said metal and the production of hydrogen. This process is used to store electricity and return it as hydrogen.
• the present invention aims to satisfy at least one of the objectives set out below.
• One of the essential objectives of the present invention is to provide an improved method of producing gaseous hydrogen gas under electrochemically pressure, in a decoupled manner, to achieve high hydrogen gas pressures for example> 80 bar.
• One of the essential objectives of the present invention is to provide an improved and simple process for the production of gaseous hydrogen gas under electrochemical pressure in a decoupled manner.
• One of the essential objectives of the present invention is to provide an improved method of producing gaseous hydrogen gas electrochemically under pressure, without decoupling, and without sacrificing industrial safety requirements.
• One of the essential objectives of the present invention is to provide an improved and economical process for the electrochemically generated production of gaseous hydrogen gas in a decoupled manner.
• One of the essential objectives of the present invention is to provide an improved method of producing gaseous hydrogen under pressure electrochemically, decoupled and in compliance with environmental constraints.
• One of the essential objectives of the present invention is to provide an improved method for the production of gaseous hydrogen gas under electrochemical pressure in a decoupled manner and whose implementation is possible in a non-industrial and non-controlled environment. specialized operators, that is to say on a gaseous hydrogen distribution site, completely autonomously.
• One of the essential objectives of the present invention is to provide an industrial device, reliable, efficient, economical and robust, for the implementation of the method as referred to in one of the above objectives.
• an electrochemical process for the production of gaseous hydrogen under pressure characterized in that it consists essentially of implementing, in a decoupled manner, the least one electrolysis step E ? of an electrolyte preferably aqueous, this electrolysis step E ? producing gaseous oxygen in an enclosure E ? and at least one step of electrochemically converting H + ions into gaseous hydrogen in an enclosure C ° which is the same or different from the enclosure E1 and which contains a liquid phase L and a gaseous phase G undissolved in this liquid phase;
• Electrolysis step E ? involves at least one cathode on which at least one ionic species is reduced electrochemically and an anode on which at least one oxygen evolution reaction takes place;
• the hydrogen gas produced in the conversion step C ° is partly present in the sky of the enclosure C ° and in the state of bubbles in the electrolyte and partly dissolved in the electrolyte which is found thus saturated, or even supersaturated, in hydrogen;
• the electrolyte comprises at least one redox couple (A / B) forming at least one intermediate vector enabling decoupling of the steps E '& C ° , with:
• the interface between the undissolved gas phase G and the liquid phase L-hereinafter called the G / L-interface is increased at least during step C °, so as to accelerate the diffusion, of the liquid phase to the gaseous phase, dissolved hydrogen that can oversaturate the electrolyte;
• the process according to the invention is particularly efficient and advantageous in that it consists in carrying out an electrochemical compression integrated into the electrolysis of an electrolyte, preferably aqueous, and, more preferably still water, so as to directly produce water.
• an electrolyte preferably aqueous, and, more preferably still water, so as to directly produce water.
• hydrogen under very high pressure decoupled, by means of an intermediate vector consisting of a pair of redox (A / B), in 2 independent steps: electrolysis with evolution of oxygen and oxidation of B to A with release of hydrogen.
• This method overcomes the difficulty related to the desired increase of the hydrogen gas pressure.
• This overpressure causes two problems.
• the first problem is the solubilization of hydrogen in the electrolyte, in particular in the electrolyte formed by an aqueous solution containing ions.
• the second problem is the possible supersaturation of the electrolyte in dissolved hydrogen. This supersaturation is defined as the ratio between the dissolved gas concentration and its solubility, that is, the equilibrium concentration.
• the method of the invention conveniently remedies this by implementing operations and associated means, allowing the increase of the G / L interface at least during step C °, preferably only during this step C °, in promoting diffusion desorption of the dissolved gas supersaturating the electrolyte.
• the increase of the interface is carried out by implementing at least one of the following operations: (i) the forced circulation which preferably consists in generating an electrolyte flow in the enclosure EC ° or C °, more preferably, using at least one pump so as to evacuate and renew the bubbles of gases present on the electrode or the electrodes or the catalyst (s) and on any roughness of the enclosure E3 ⁇ 4 ° or C °;
• At least one depolarization preferably at least one localized depolarization of the electrolyte, which preferably consists of accelerating the kinetics of the hydrogen formation reaction to locally increase the supersaturation and promote the formation of bubbles ,
• the present invention relates to devices for implementing the method.
• kits for carrying out the method comprising a device and at least a part of the components for the preparation of the electrolyte or electrolytes intended to be contained in the enclosure or the enclosures of the device
• any singular denotes indifferently a singular or a plural.
• E ° standard potential.
• the standard potentials E ° referred to in this presentation are all measured under the same conditions (reference, temperature, concentrations).
• the electrochemical compression specific to the process according to the invention is integrated in a decoupled and independent 2-step process, namely, on the one hand, the electrolysis of at least one of the ions contained in the electrolyte (preferably an aqueous solution ), and, on the other hand, the oxidation of at least one of the reduced species to the cathode during electrolysis, concomitantly with the production of hydrogen, by reduction of H + ions contained in the electrolyte.
• Spray the electrolyte is sprayed into the gaseous atmosphere of the reactor.
• Hot point the solubility of hydrogen decreases with temperature. By applying a hot spot or several hot spots in the electrolyte, the supersaturation is locally increased, and in doing so, the appearance of bubbles is promoted.
• the principle here is to make bubbles appear by generating ultrasound in the supersaturated electrolyte, in a similar way to the phenomenon of acoustic cavitation.
• the bubbles thus generated absorb the supersaturant electrolyte gas and remain stable.
• the electrolyte is preferably an acidic or basic aqueous solution, or an ionic liquid.
• the electrolyte is such that the species [ions Y y + , Y y , H + , OH] that it contains, other than A & B, are not reduced or oxidized before A and B.
• these species other than A & B do not react electrochemically in a potential window bounded by the potential of the electrode on which the A / B couple reacts and the potential of the electrode on which the 0 2 / H 2 0 reacts. in an acidic medium or 0 2 / 0Ll in basic medium.
• A is present in the electrolyte in a concentration range between 0.1 and 15 mol.L 1 , preferably between 0.2 and 10 mol.L 1
• step C ° for the implementation of step C °:
• At least one hydrogen electrode is immersed in the electrolyte and allows the production of hydrogen gas by reduction of the H + ions of the electrolyte;
• the electrolyte comprises at least one catalyst.
• the decoupling is made possible by the implementation of an intermediate vector consisting of at least one Redox couple (A / B).
• This redox couple (A / B) is advantageously characterized by the following two properties:
• thermodynamic potential of the redox pair E th (A / B) is preferably lower than that of the pair (0 2 / H 2 0) [E th (A / B) ⁇ E th (0 2 / H 2 0] in medium acid, and lower than that of the pair (0 2 / OH) [E th (A / B) ⁇ E th (0 2 / OH)] in basic medium.
• the potential difference in absolute value between these two redox couples A / B and 0 2 / OH or 0 2 / H 2 0 is ideally greater than or equal to 100 mV. This potential difference in absolute value may for example be between 0.2 and 2V.
• B may comprise at least one solid species.
• at least one hydrogen electrode is immersed in the electrolyte and allows the production of hydrogen gas by reduction of H + ions of the electrolyte.
• the thermodynamic potential of the pair A / B is lower than that of the hydrogen evolution reaction (H + / H 2 ).
• This redox couple (A / B) is then defined as follows:
• A is composed of at least one metal ion of the metal M
• B is composed of at least metal M
• M preferably selected from metals, and more preferably still in the group consisting of - ideally consisting of -: Zn; Cd; Sn, Ni, Mn, Fe, Pb, Co; Zn being particularly preferred.
• the metal is chosen so that it can be deposited during the electrolysis step E ? on the cathode, with the electrolyte considered, with the best possible yield.
• the metal salt A can take the form of hydrated or complex ions.
• A is electrolyzed on a suitable cathode, which leads to a deposition of B on this cathode.
• the particularly preferred redox A / B pairs are: Zn 2+ / Zn, Cd 2+ / Cd, Sn 2+ / Sn.
• the electrolysis step E ? and the conversion step C ° are carried out in at least one same enclosure EC ° containing electrolyte in which are immersed at least 3 electrodes, namely at least one cathode on which the reduced metal M is deposited during the electrolysis step E 1, at least one anode in the vicinity of which is produced the gaseous oxygen resulting from the oxidation of the water during the electrolysis step E ? and at least one inactive hydrogen electrode during the electrolysis step E ? in the vicinity of which is produced hydrogen gas from the reduction of H + ions of the electrolyte during the conversion step C °;
• a power supply connected to the cathode and the anode delivers an electric current, so that the metal M is deposited on the cathode and oxygen gas is released at the anode;
• the cathode of step E ? becoming the anode of step C ° is connected to the hydrogen electrode by an electrical conductor so as to function as a battery being discharged, so that the metal M solubilizes in the electrolyte to the anode of C ° and that hydrogen gas emerges and is compressed in the sky of the enclosure E'C ° close,
• ⁇ and means for increasing the interface G / L are operable to facilitate the transformation of the dissolved gas, particularly hydrogen, in the electrolyte in undissolved gas.
• the electrolyte is an aqueous saline solution comprising at least one metal salt M preferably chosen from: sulphates, nitrates, chlorides, citrates, phosphates, carbonates, fluorides, bromides, oxides, aqueous solutions of alkali metal hydroxide or alkaline earth metal or mixtures thereof; as well as an acid or Bronsted base;
• metal salt M preferably chosen from: sulphates, nitrates, chlorides, citrates, phosphates, carbonates, fluorides, bromides, oxides, aqueous solutions of alkali metal hydroxide or alkaline earth metal or mixtures thereof; as well as an acid or Bronsted base;
• the cathode is made from a material allowing the deposition of the metal M with a Faraday yield of at least 30%, preferably at least 50%, this material being preferably chosen from the group of metals and / or metal alloys, comprising - and ideally composed of: Al, Pb and Pb alloys, carbon, nickel, and / or iron materials, stainless steels, and combinations of these materials;
• o the anode is made from a chosen material:
• metals and / or metal alloys comprising and ideally composed of: Pb and Pb alloys, in particular Pb-Ag-Ca or Pb-Ag alloys, steels, iron, nickel;
• oxides preferably metal oxides, or oxides of perovskite structure
• DS A Dimensionally Stable Anode
• the hydrogen electrode is made from a material chosen from transition metals, lanthanides and / or alkaline earths and, more preferably still, from the group comprising and ideally composed of platinum and platinoids in the form of metal or oxide, tungsten, molybdenum, titanium or zirconium in the form of oxides, carbides, sulphides or borides, silver, nickel, iron, cobalt and alloys at least one or these elements, the composites formed by one of these elements or an alloy with an oxide, the carbon-based materials (eg fine carbon particles, organometallic material, graphene) and the combinations of these materials.
• transition metals lanthanides and / or alkaline earths
• platinum and platinoids in the form of metal or oxide, tungsten, molybdenum, titanium or zirconium in the form of oxides, carbides, sulphides or borides, silver, nickel, iron, cobalt and alloys at least one or these elements, the composites formed by one of these elements or
• the invention uses the property that certain metals or alloys kinetically block the release of hydrogen is the phenomenon called hydrogen surge, leading to an electrochemical state out of equilibrium.
• This era the step E? consists in performing an electrolysis between the cathode and the anode, which leads to an evolution of oxygen and to a local variation of the pH of the electrolyte at the anode resulting from the non-evolution of hydrogen gas and an accumulation of energy corresponding to the non-equilibrium state.
• the cathode is the seat of an electrochemical reduction from A to B.
• the cathode material advantageously has a high overvoltage for the hydrogen evolution reaction with the electrolyte of interest.
• This overvoltage may, for example, be greater than or equal to 50 mV.
• the cathode material may be aluminum, a lead-based alloy, a nickel-based alloy, and / or iron, a stainless steel, a carbon-based material or a combination of these materials.
• the cathode and the anode both plunge into the same electrolyte, without physical separation between them.
• the second step C ° of this variant No. 1 of the first embodiment consists in implementing the solutions for restoring the equilibrium state by releasing the energy accumulated during step E ⁇ , c 'is to say:
• This second step C ° comprises, according to the invention, the implementation of specific operations and associated means, to release the release of gaseous hydrogen under pressure from two obstacles, namely: the blocking of the electrochemical kinetics and the solubilization of hydrogen in the electrolyte.
• step E1 It is inactive during the electrolysis phase (step E1) and is polarized during the conversion step C °, by discharge between itself and the electrode on which the metal is deposited.
• This 3rd hydrogen electrode is, for example, made from platinum or other platinum group metals as metal or tungsten carbide.
• R, T and F are respectively the perfect gas constant, the electrolyte temperature and the Faraday constant.
• x 5 is related to its equilibrium value with the gas phase by the expression a * 3 ⁇ 4 _ fs "3 ⁇ 4 ⁇ At a given measured pressure, it is therefore possible to measure this supersaturation from the offset of the potential of the hydrogen electrode with respect to its equilibrium value:
• this voltage shift is 24mV, which is in the measuring range of a reference electrode.
• desorption of the supersaturated gas is observed, which is generally accompanied by an increase in pressure.
• the decrease in the level of supersaturation is related both to the decrease in the concentration of dissolved gas and also to the increase in its solubility due to the increase in pressure.
• the potential shift tends to 0 once the dissolved gas concentration has reached equilibrium with the gas phase.
• the objective of increasing the pressure of gaseous oxygen produced thus causes the appearance of two phenomena namely, on the one hand the increase in solubility and, on the other hand, the appearance of a supersaturation. In both cases, this leads to a trapping of hydrogen in the electrolyte.
• the arrangement according to the invention for increasing the G / L interface to increase the diffusion of the electrolyte supersaturated hydrogen gas contributes to the elimination of these antagonistic phenomena.
• the Redox couple is an ion / ion pair.
• This redox couple (A / B) is then defined as follows:
• A is composed of at least one ion I A of number of electrons of valence V 1;
• I B is composed of at least one ion I B of number of electrons of valence V2 ⁇ VI; with I preferably selected from ions from atoms selected from the group consisting of - ideally composed of -: Fe; U; Cr; S; V; iron and vanadium being particularly preferred.
• a and B each comprise at least one ionic species
• the electrolyte comprises at least one hydrogen electrode and / or at least one catalyst during step C °.
• This variant No. 2 can be executed according to 3 sub-variants.
• the return to equilibrium is achieved through a hydrogen electrode, while in a 2nd sub Alternatively, the return to equilibrium takes place with a catalyst; 3rd sub variant being a combination of the first two.
• Sub-variant No. 1 (Fl.2.1): Use of a hydrogen electrode for the conversion step C °.
• the following modalities are preferably selected:
• a power supply connected to the cathode and the anode delivers an electric current, so that the ions I A are reduced to ions I B at the cathode and so that the oxidation water leads to a release of gaseous oxygen at the anode;
• the chamber is hermetically sealed E'c 0, ⁇ the cathode of step E ? becoming the anode of step C °, is connected to the hydrogen electrode by an electrical conductor so as to operate as a battery being discharged, in the EC ° enclosure, thereby catalyzing the oxidation reaction I B ions in I A ions in the compartment (J) concomitant with a reduction of H + ions contained in the compartment (K) in gaseous hydrogen, which disengages and compresses in the sky of the enclosure E'C ° close,
• ⁇ and means for increasing the interface G / L are operable to facilitate the transformation of the dissolved gas, particularly hydrogen, in the electrolyte in undissolved gas;
• step C ° the H 2 electrode is disconnected from the cathode of step E 1 .
• Sub-variant No. 2 (Fl.2.2): Use of a catalyst for the conversion step C °.
• This enclosure E'C ° includes:
• a power supply connected to the cathode and to the anode delivers an electric current, so that the ions I A are reduced to ions I B at the cathode and so that the oxidation water leads to a release of gaseous oxygen at the anode;
• a catalyst is introduced into the catholyte in the compartment (D) of the enclosure E'c ° hermetically sealed, to catalyze the oxidation reaction of ions I B ions I A concomitant with a reduction of H + ions contained in the catholyte in gaseous hydrogen, which is disengaged and compressed in the sky of the enclosure E'C ° close,
• ⁇ and means for increasing the interface G / L are operable to facilitate the transformation of the dissolved gas, particularly hydrogen, in the electrolyte in undissolved gas;
• step C ° the catalyst is extracted from the enclosure E'C °.
• the enclosure E ? comprises:
• a power supply connected to the cathode and the anode delivers an electric current, so that the ions I A are reduced to ions I B at the cathode and so that the oxidation water leads to a release of gaseous oxygen at the anode;
• the catholyte was transferred to a chamber C ° hermetically sealed, which contains at least one oxidation reaction catalyst ions I B ions I Co A to a reduction of H + ions contained in the catholyte by hydrogen gas, which disengages and compresses itself in the sky of the enclosure C ° close,
• the catholyte resulting from the conversion step C ° is preferably re-transferred to the enclosure E ? for a new electrolysis E ⁇
• the electrolysis step E ? and the conversion step C ° are performed in two separate enclosures E 1 and C 0.
• the electrolysis step E ? and the conversion step C ° are performed in the same chamber EC °.
• This variant No. 2 may also be characterized by at least one of the following specifications:
• the catholyte is an aqueous saline solution comprising at least one ion salt A whose counterion is preferably chosen from the following ions: S0 4 2 , NO 3 , their mixtures;
• the anolyte is an acidic or basic aqueous salt solution
• the cathode is made from an electronically conductive material, this material preferably being chosen from the group of metals and / or metal alloys, comprising -and ideally composed of: Al, Pb and Pb alloys, materials with base of carbon, nickel, and / or iron, stainless steels, and combinations of these materials;
• metals and / or metal alloys comprising and ideally composed of: Pb and Pb alloys, in particular Pb-Ag-Ca or Pb-Ag alloys, or steels, iron, nickel;
• oxides preferably metal oxides, or even oxides of perovskite structure
• DSA Dimensionally Stable Anode
• the hydrogen electrode is made from a material chosen from transition metals, lanthanides and / or alkaline earths and, more preferably still, from the group comprising and ideally composed of platinum and the platinum compounds in the form of metal or oxide, tungsten, titanium, zirconium or molybdenum in the form of oxide, carbide, sulphide or borides, silver, nickel, iron, cobalt and base alloys at least one or these elements, the composites formed by one of these elements or an alloy with an oxide, the carbon-based materials (fine particles of carbon, organometallic material, graphene) and the combinations of these materials;
• the catalyst comprises at least one material chosen from transition metals, lanthanides and / or alkaline earths and, more preferably still, from the group comprising and ideally composed of: platinum and platinoids in the form of metal or of oxide, tungsten, titanium, zirconium or molybdenum in the form of oxides, carbides, sulphides or borides, silver, nickel, iron, cobalt and alloys based on at least one or of these elements, the composites formed by one of these elements or alloy with an oxide, the carbon-based materials (fine carbon particles, organometallic material, graphene) and the combinations of these materials.
• step E ? of variant No. 2 A is electrochemically reduced to B at the cathode.
• the cathode and the anode as well as their respective electrolytes will be physically separated by a membrane, and this couple A / B is present only in the catholyte.
• a / B pair mention may be made of: V 3+ / V 2+ , Fe (CN) 6 3 7 Fe (CN) 6 4 .
• step C ° of this variant No. 2 it consists in implementing the solutions enabling the state of equilibrium to be restored by releasing the energy accumulated during the step E ⁇ , that is -to say :
• the acceleration of the hydrogen evolution kinetics is effected by means of at least one hydrogen electrode, the electrode material is chosen according to the same criteria as in variant No. 1.
• the acceleration of the hydrogen evolution kinetics is carried out by means of at least one catalyst.
• the catalyst is chosen for its good electrocatalytic properties and low overvoltage for the hydrogen evolution reaction (eg platinoids and their derivatives, carbides and sulphides of tungsten or molybdenum, nickel, etc.).
• thermodynamic potential of the A / B pair is greater than that of the hydrogen evolution reaction (H + / H 2 ) [E th (A / B)> E th H + / H 2 )] in an acid electrolyte, and higher than that of the pair (H 2 0 / H 2 ) [E th (A / B)> E th (H 2 O / H 2 )] in a basic electrolyte, and is less than that of oxygen evolution.
• This redox couple (A / B) is then defined as follows:
• A is composed of at least one metal ion of the metal M
• B is composed of at least metal M
• M preferably selected from metals, and more preferably still in the group comprising - ideally composed of -: Cu, Mn, Ag; Cu being particularly preferred.
• the metal is chosen so that it can be deposited during the electrolysis step E ? on the cathode, with the electrolyte considered, with the best possible yield.
• the metal salt A may take the form of hydrated or complex ions.
• A is electrolyzed on a suitable cathode, which leads to a deposition of B on this cathode.
• the following modalities are preferably selected: the electrolysis step E ⁇ and the conversion step C ° are carried out in a single enclosure E'C °;
• a power supply connected to the cathode and the anode delivers an electric current, so that Mm + ions are deposited in the form of metal M at the cathode and so that the oxidation water leads to a release of gaseous oxygen at the anode;
• the cathode of step E ? becoming the anode of step C ° is connected to the hydrogen electrode by a power supply that delivers an electric current so that the metal M is oxidized to M + ions in the compartment (J) concomitant to a reduction H + ions contained in the compartment (K) in gaseous hydrogen, which disengages and compresses in the sky of the enclosure E'C ° close,
• ⁇ and means for increasing the interface G / L are operable to facilitate the transformation of the dissolved gas, particularly hydrogen, in the electrolyte in undissolved gas;
• step C ° the H 2 electrode is disconnected from the cathode of step E.
• Variant No. 2 (F2.2): The Redox couple is an ion / ion pair.
• This redox couple (A / B) is then defined as follows:
• A is composed of at least one ion I A of number of electrons of valence V 1;
• I B is composed of at least one ion I B of number of electrons of valence V2 ⁇ VI; with I preferably selected from ions from atoms selected from the group consisting of - ideally composed of -: Fe, V, Mn; iron and vanadium being particularly preferred.
• a and B each comprise at least one ionic species.
• a power supply connected to the cathode and to the anode delivers an electric current, so that the ions I A are reduced to ions I B at the cathode and so that the oxidation of the water leads to a release of gaseous oxygen at the anode;
• ⁇ the cathode of step E ? becoming the anode of step C °, is connected to the hydrogen electrode by a power supply so as to carry out the electrochemical oxidation reaction of ions I B in ion I A concomitant with an electrochemical reduction of H + ions contained in the anolyte of gaseous hydrogen, which is disengaged and compressed in the sky of the enclosure E'C ° close, ⁇ and means for increasing the interface G / L are operable to facilitate the transformation of the dissolved gas, particularly hydrogen, in the electrolyte in undissolved gas;
• step C ° the electrode at H 2 is disconnected from the cathode of step E '.
• This variant No. 2 may also be characterized by at least one of the following specifications:
• the catholyte is an aqueous saline solution comprising at least one ion salt A whose counterion is preferably chosen from the following ions: S0 4 2 , NO 3 , their mixtures;
• the anolyte is an acidic or basic aqueous salt solution
• the cathode is made from an electronically conductive material, this material preferably being chosen from the group of metals and / or metal alloys, comprising -and ideally composed of: Al, Pb and Pb alloys, materials with base of carbon, nickel, and / or iron, stainless steels, and combinations of these materials;
• metals and / or metal alloys comprising and ideally composed of: Pb and Pb alloys, in particular Pb-Ag-Ca or Pb-Ag alloys, steels, iron, nickel;
• oxides preferably metal oxides, or even oxides of perovskite structure
• DSA Dimensionally Stable Anode
• the hydrogen electrode is made from a material chosen from transition metals, lanthanides and / or alkaline earths and, more preferably still, from the group comprising and ideally composed of platinum and platinoids in the form of metal or oxide, tungsten, titanium, zirconium or molybdenum in the form of oxide, carbide, sulphide or borides, silver, nickel, iron, cobalt and alloys of at least one or these elements, the composites formed by one of these elements or alloy with an oxide, the materials carbon-based (fine carbon particles, organo-metallic material, graphene) and the combinations of these materials.
• step E 'of this variant No. 2 A is reduced electrochemically in the form of B at the cathode.
• the cathode and the anode as well as their respective electrolytes will be physically separated by a membrane, and this couple A / B is present only in the catholyte.
• a / B pair mention may be made of: V0 2 + / V0 2+ , V0 2+ / V 3+ , Fe (CN) 6 3 VFe (CN) 6 4 .
• step C ° of this variant No. 2 it consists in implementing the solutions enabling the state of equilibrium to be restored by releasing the energy accumulated during the step E ⁇ , that is -to say :
• a power supply connected to the cathode and the anode delivers an electric current, so that the A ions are reduced in the form of B to the cathode and so that the oxidation water leads to a release of gaseous oxygen at the anode;
• ⁇ the enclosure E'C ° is hermetically closed, ⁇ the cathode of step E 'becomes the anode of the step C °, is connected to the hydrogen electrode by a power supply which supplies an electric current so that the gear B are oxidized to ions in the A compartment (J) concomitant with a reduction of the H + ions contained in the compartment (K) in gaseous hydrogen, which is disengaged and compressed in the sky of the enclosure E'C ° close,
• ⁇ and means for increasing the interface G / L are operable to facilitate the transformation of the dissolved gas, particularly hydrogen, in the electrolyte in undissolved gas.
• the acceleration of the hydrogen evolution kinetics is effected by means of at least one hydrogen electrode, the electrode material is chosen according to the same criteria as in variant No. 1 of the first embodiment of the invention. artwork.
• This arrangement is also a possible operation to increase the G / L interface according to the invention.
• the present invention relates to devices for implementing the method.
• the reference device for the first mode of operation (F 1) L comprises: a. at least one closed enclosure E'C ° intended to contain at least one electrolyte; b. at least one cathode intended to be immersed in the electrolyte;
• vs. at least one anode intended to be immersed in the electrolyte
• At least one hydrogen electrode for being immersed in the electrolyte; e. a power supply for connecting the cathode to the anode;
• the preferred device for the subvariant _N ° 1 _ (F 1.2.1) __________________ variant_ 2 variant FJL.2) of the first mo dc dc dd dc dccji -vrç_ (F 1_) comprises:
• At least one enclosure E'C ° close comprising:
• step E b at least one cathode of step E ⁇ intended to be immersed in the catholyte; vs'. at least one anode of the step E 'intended to be immersed in the anolyte; of. at least one electrode to H 2 to be placed in the 2nd electrochemical compartment (K) and operative when electrically connected to the cathode of step E ⁇ become anode of step C ° to behave like a stack during discharge, the oxidation reaction of I B ions into I A ions; e. a power supply for connecting the cathode of step E 'to the anode of step E1;
• h optionally means for circulating the electrolyte or electrolytes in the enclosure E'C °;
• pour_la_s_o_us_-yari_ante # 2 ( ⁇ ⁇ J2.2 ⁇ irst _aJtc_rnatiy: c_ (FliL2, the 2_ e "variant _ (F_1_ .2), the first _mgde_de mise_en_ Artwork (Fl) comprises!:
• catholyte including the redox couple (A / B),
• ⁇ at least one ion exchange membrane, preferably cationic, separating the two compartments;
• step E at least one anode from step E to be immersed in the anolyte;.? d" .l. a power supply for connecting the cathode of step E ? at the anode of step E1;
• f'.l. optionally means for circulating the electrolyte or electrolytes in the enclosure E'C °;
• the preferred device for _a_ squ s-ya_r [an t c_N / J 2_ (F 1.2.2 second alternat iyc fF 1.2.2.2), the _2_ em ! ariant JTL ⁇ ⁇ the first modejde niise _EN_ Artwork (Fl) comprises: a ".2. at least one enclosure E ? comprising:
• catholyte including the redox couple (A / B), and at least one electrochemical compartment (K) for containing an anolyte
• At least one membrane preferably cationic, separating these two compartments
• step E1 intended to be immersed in the catholyte
• step E1 at least one anode of step E1 to be immersed in the anolyte; a power supply for connecting the cathode of step E ? at the anode of step E1;
• f'.2. means for increasing the G / L interface
• . g ".2 means for circulating the electrolyte or electrolytes between the speakers and E ° C;
• At least one enclosure E 1 C ° close comprising:
• ⁇ at least one membrane, preferably cationic, separating the two compartments;
• step E ⁇ intended to be immersed in the electrolyte of the compartment (J);
• At least one hydrogen electrode intended to be immersed in the electrolyte of the compartment (K);
• step E ? at least one power supply for connecting the cathode of step E ? at the anode (d) of step E1; af. at least one power supply for connecting the cathode of step E ? , become the anode of step C °, to the hydrogen electrode;
• ag. means for increasing the G / L interface
• electrolyte including the redox couple (A / B),
• ⁇ at least one membrane, preferably cationic, separating these two
• step E ⁇ intended to be immersed in the electrolyte compartment (J);
• At least one hydrogen electrode intended to be immersed in the electrolyte of the compartment (K);
• step E1 at least one power supply for connecting the cathode of step E ? at the anode (d) of step E1;
• ah ' optionally means for circulating the electrolyte or electrolytes in the enclosures E ? and C °;
• electrolyte including the redox couple (A / B),
• ion exchange membrane preferably cationic
• ad at least one hydrogen electrode to be immersed in the electrolyte of compartment K;
• the present invention also relates to a kit for implementing the method.
• This kit is characterized in that it comprises:
• This kit which forms a packaging unit for sale, may also include an explanatory note for the implementation of the method using the device and components contained in this kit.
• Figure 1A is a schematic representation of the device implemented in the electrolysis step of Example 1;
• Figure 1B is a schematic device representation implemented in the electrochemical conversion step C ° of Example 1;
• Figure 2A is a schematic representation of the device implemented in the electrolysis step E ? of Example 2;
• FIG. 2B is a schematic device representation implemented in the electrochemical conversion step C ° of example 2.
• Figure 3A is a schematic representation of the device implemented in the electrolysis step E ? of Example 3;
• FIG. 3B is a schematic device representation implemented in the electrochemical conversion step C ° of example 3.
• EXAMPLE 1 1st Implementation Mode / Variant No. 1: F1
• hydrogen was produced at 200 bar in the device represented in FIG. 1 A.
• This device is a electrochemical reactor composed of a closed chamber 1 in which there are three electrodes 3,4,5 bathed in an acidic aqueous solution (electrolyte) 2.
• the three surface electrodes 1 m 2 are as follows:
• Electrolyte 2 is composed of zinc ions (concentration 1.5 mMol) and sulfuric acid (2.55 moles / L). It is prepared by mixing 67 kg of sulfuric acid (37.5%, Brenntag) in 28.6 L of deionized water, and then adding to this mixture 45 kg of zinc sulphate (ZnSO 4 , 7H 2 O) (97, 5%, Platret).
• the reactor 1 is equipped with heating means 6 constituted by exchangers and which make it possible to maintain the temperature of the electrolyte 2 at 30 ° C.
• Reactor 1 is provided with a conduit 8 gas outlet, which conduit is subdivided into a pipe 11 for evacuation of oxygen gas and a pipe 10 for evacuation of hydrogen gas.
• Each line 10, 11 is equipped with a valve 9, 12 respectively valve 0 2 and valve H 2 , allowing independent extraction of these 2 gases out of the enclosure 1 high pressure.
• a power supply 7 connected to the cathode 3 and the anode 4 provides a current density of 595 A / m 2 for 5 hours, which allows to deposit 3267 g of zinc on the cathode ( with a Faraday yield of 90%).
• the second step C ° is a step of converting into electricity the electrochemical energy stored in the form of zinc deposited on the cathode (FIG. 1B).
• the cathode 3 is electrically connected to the hydrogen electrode 5 via an electronic charge 13.
• the hydrogen evolution rate is 350 mol / h / m 2 and it takes 4 hours 40 minutes to produce 50 mol of hydrogen . In the absence of a device for suppressing the supersaturation, it reaches a rate of about 6. This results in a shift in the potential of the hydrogen electrode, measured using a reference electrode, of 24 mV with respect to its equilibrium value, and a pressure reached of about 85 bar, with about 70% of the hydrogen produced trapped in dissolved form.
• Ultrasound is then applied by a piezoelectric generator 14 in a frequency range corresponding to the appearance of the acoustic cavitation phenomenon.
• the supersaturation rate is reduced to 1, the offset of the equilibrium potential of the hydrogen electrode to 0 and the pressure then reaches about 200 bars, with a quantity of hydrogen trapped in dissolved form which is only about 26%.
• the device represented in FIG. 2A comprises an enclosure E ! which is an electrochemical cell 1 consisting of two compartments (J, K), respectively containing a cathode 4 and an anode 5, each having a surface of 150 cm 2 , and an electrolyte (catholyte 2 and anolyte 3) of 250 ml each .
• the two electrolytes 2 and 3 are separated by a cationic membrane 6 made of Nafion 125.
• the electrodes are made of carbon felt.
• a power supply 7 is connected to the cathode 4 and to the anode 5.
• the catholyte 2 is prepared from sodium polysulfide Na 2 S.9H 2 O (1.6 mol.L 1 ), and the anolyte 3 is a sulfuric acid solution at 1 mol.L 1 .
• the catholyte is prepared by mixing 96.1 g of Na 2 S, 9H 2 O (99.99%, Sigma Aldrich) and 185 g of deionized water.
• the anolyte is prepared by mixing 66 g of sulfuric acid (37.5%, Brenntag) in 200 mL of deionized water.
• This oxygen is evacuated via a pipe 8 equipped with a valve 9.
• the power supply 7 allows to apply a current of 50 mA / cm 2 for 2h20.
• the yield of Faraday is 80%, and the concentration of S 4 2 ions is 0.6 mo 1 / L at the end of this step E '.
• the catholyte is transferred via a pipe 10 equipped with a valve 1 1 to the chamber where the second step takes place.
• Step C ° ( Figure 2B) allows the production of hydrogen; the catholyte 2 is sent via a pump 13 into a chemical reactor 12 containing tungsten carbide balls 14. Two simultaneous reactions take place:
• the concentration of sulfide ions 2 S 4 is again 1.6 mol / L, and 0.25 g of H 2 are generated.
• this hydrogen makes it possible to inflate a small cartridge of 15 ml at about 110 bar, with a potential shift of the hydrogen electrode of 24mV, measured with the aid of a reference electrode.
• Alumina nanoparticles present in the reactor 12 make it possible to accelerate the nucleation of the hydrogen gas and to reduce the degree of supersaturation to 1. The desorption of hydrogen then makes it possible to reach 250 bars in the cartridge.
• This device is a reactor / closed electrochemical chamber 1 composed of two compartments (J, K) of 1 L each.
• the I. J compartment contains a carbon electrode 2 (which acts as the cathode during the electrolysis step st E 1).
• the 2nd K compartment contains an electrode on which oxygen is released when the era electrolysis step E1 (anode) alloy lead-silver-calcium 3 and an electrode on which hydrogen at untap of the 2 nd step ° C (hydrogen electrode) in plate 4.
• the surface of each electrode is 155 cm 2 .
• a National 125® 5 membrane separates the electrodes from each compartment.
• the electrolyte (catholyte) 6 of blue color contained in 1 is composed of vanadium ions VO 2 + (concentration 2 mol / L) and sulfuric acid (2 mol / L). It is prepared by mixing 520 g of sulfuric acid (37.5%, Brenntag) in 590 ml of deionized water, and then adding to this mixture 325 g of hydrated vanadium sulfate oxide (V0SO 4 xH 2 0; 99.9% Alfa Aesar).
• the electrolyte (anolyte) 7 contained in the second compartment K is a 2 mol / l sulfuric acid solution. It is prepared by mixing 520 g of sulfuric acid (37.5%, Brenntag) in 590 ml of deionized water.
• a power supply 8 connected to the cathode 2 and to the anode 3 provides a current density of 300 A / m 2 for 1 h.
• the oxygen is evacuated via the pipe 9 controlled by the valve 10.
• the cathode 2 (which then acts as an anode) and the electrode to H 2 4 are connected to the power supply 8 which supplies 300 A / m 2 during lh. 1.2 g of hydrogen at 16 bar are produced.
• the hydrogen released alone then rises under pressure as electrolysis progresses.
• Localized heating 11 makes it possible to increase the temperature of the electrolyte in a localized manner, which leads to desaturation of the electrolyte.
• the hydrogen gas formed is discharged through the pipe 12 controlled by the valve 13 when the target pressure (16 bar) is reached.

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