EP4399346A1 - Appareil et procédé de production de peroxyde d'hydrogène - Google Patents

Appareil et procédé de production de peroxyde d'hydrogène

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Publication number
EP4399346A1
EP4399346A1 EP22830454.9A EP22830454A EP4399346A1 EP 4399346 A1 EP4399346 A1 EP 4399346A1 EP 22830454 A EP22830454 A EP 22830454A EP 4399346 A1 EP4399346 A1 EP 4399346A1
Authority
EP
European Patent Office
Prior art keywords
cathode
layer
gas
hydrogen peroxide
gas diffusion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22830454.9A
Other languages
German (de)
English (en)
Inventor
Rajath SATHYADEV RAJMOHAN
Rasmus FRYDENDAL
VERDAGUER CASADEVALL Arnau
Ziv Gottesfeld
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hpnow Aps
Original Assignee
Hpnow Aps
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP21212606.4A external-priority patent/EP4190943A1/fr
Priority claimed from US17/889,599 external-priority patent/US20240060195A1/en
Application filed by Hpnow Aps filed Critical Hpnow Aps
Publication of EP4399346A1 publication Critical patent/EP4399346A1/fr
Pending legal-status Critical Current

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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
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/722—Oxidation by peroxides
    • 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
    • C25B1/28—Per-compounds
    • C25B1/30—Peroxides
    • 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
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
    • C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
    • C25B11/031—Porous electrodes
    • C25B11/032—Gas diffusion electrodes
    • 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
    • C25B9/13—Single electrolytic cells with circulation of an electrolyte
    • C25B9/15—Flow-through 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
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/30—Treatment of water, waste water, or sewage by irradiation
    • C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/78—Treatment of water, waste water, or sewage by oxidation with ozone
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46133—Electrodes characterised by the material
    • C02F2001/46138—Electrodes comprising a substrate and a coating
    • C02F2001/46142—Catalytic coating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
    • C02F2103/023—Water in cooling circuits
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus
    • C02F2201/46105—Details relating to the electrolytic devices
    • C02F2201/46115—Electrolytic cell with membranes or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/04—Disinfection
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/02—Specific form of oxidant
    • C02F2305/023—Reactive oxygen species, singlet oxygen, OH radical
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/02—Specific form of oxidant
    • C02F2305/026—Fenton's reagent

Definitions

  • the present invention relates to an apparatus and a method for producing hydrogen peroxide.
  • the present invention further relates to a system using the apparatus to produce hydroxyl radicals, and to a method of producing the apparatus. More precisely, the present invention relates to an improved apparatus and method that employs oxygen reduction for producing hydrogen peroxide.
  • Hydrogen peroxide is a versatile chemical, used as an oxidant in industries such as pulp and paper, water treatment and agriculture.
  • the on-site production of hydrogen peroxide from readily available compounds is highly attractive for these industries, as it would enable supply independence and would be more sustainable.
  • Electrolysis cells offer unique advantages in generating chemicals in decentralized facilities with the use of electricity as input energy rather than requiring large chemical production plants. Advantages are, among others, the generation of chemicals where and when they are needed, thereby removing the need for transportation and storage, and facilitating the use of energy produced by sustainable means, such as wind power and solar.
  • Electrochemical production of hydrogen peroxide has strong advantages over the traditional Anthraquinone process that takes place in centralized chemical facilities to produce hydrogen peroxide.
  • the Anthraquinone process involves a large amount of energy, CO2 emissions and chemical waste.
  • Natural gas is the main source of hydrogen in today’s anthraquinone plants. Since production is centralized, hydrogen peroxide needs to be transported to the point of use. For economic reasons, hydrogen peroxide is shipped at concentrations typically between 30 and 70 %, which is hazardous and poses safety concerns. Once it reaches the point of use, it often needs to be diluted to concentrations ⁇ 3 %.
  • Electrochemical production can take place using water and oxygen from the atmosphere to form H2O2 and only electricity is required as energy input, meaning that it can be a CO2 emissions-free process when using CO2-neutral electricity.
  • low concentrations below 3 wt% are needed which means safety concerns can be avoided altogether if the solutions are produced with low concentrations from the beginning.
  • the first approach has been to use liquid state ion conductors, usually in the form of an alkaline or neutral salt solution, as described for example in crizodian and Continuous Production of Hydrogen Peroxide with 93% Selectivity Using a Fuel-Cell System”, Angewandte Chemie 2003.
  • This approach has led to high efficiency and concentrations for hydrogen peroxide production, but purity is low since it is hard to separate the salts from the generated hydrogen peroxide.
  • Dissolved oxygen in water - water helps extract hydrogen peroxide, which results in high faradaic efficiencies, but on the other hand the low solubility of oxygen in water means current densities are low. Overall throughputs of hydrogen peroxide are low.
  • the present invention addresses the above discussed challenges exhibited by the production of hydrogen peroxide by providing an improved apparatus for producing hydrogen peroxide, an improved system the formation of hydroxyl radicals, a method of producing hydrogen peroxide using the apparatus of the invention and a method of producing the apparatus of the present invention. At least these and other aspects of the invention are described in detail in the appended claims.
  • the design proposed herewith for the electrochemical cell for the production of hydrogen peroxide of the present invention improves current collection and gas delivery, while at the same time facilitating hydrogen peroxide extraction from the cathode through the presence of water or a forced water flow. This optimizes utilization of the available electrode area, which results in higher throughputs, higher faradaic efficiencies and longer electrode lifetime.
  • Other benefits are a low high frequency resistance (HFR), as well as a very homogeneous distribution of current collection over the whole electrode area.
  • An apparatus comprises at least one and preferred a plurality of neighboring electrochemical cells, each electrochemical cell comprising an electrode assembly comprising at least one cathode gas diffusion layer, at least one cathode catalyst layer, at least one ion exchange membrane, at least one anode catalyst layer, and at least one anode current collector, the at least one cathode catalyst layer, the at least one ion exchange membrane and the at least one anode catalyst layer being disposed neighboring each other within the electrode assembly, being disposed in succession along an horizontal axis of the membrane electrode assembly, the apparatus further comprising at least one gas transport layer disposed neighboring the cathode gas diffusion layer, the gas transport layer being capable of facilitating a flow of oxygen-containing gas towards the cathode gas diffusion layer and being capable of current collection, the cathode gas diffusion layer comprising water.
  • a system comprises the apparatus in accordance with the present invention according to any of its aspects discussed herein, and a device facilitating the combination of hydrogen peroxide generated by the apparatus and ultra-violet light or ozone to facilitate the formation of hydroxyl radicals.
  • a method of producing hydrogen peroxide using the apparatus of the present invention, according to yet another aspect of the present invention and a method of producing the apparatus of the present invention are also discussed herewith in detail.
  • the present invention proposes at least incorporating an electrically conductive porous gas transport layer that simultaneously collects current from the cathode, and uniformly delivers oxygen gas to the cathode, while at the same time having water present in the cathode gas diffusion layer.
  • This configuration maximizes the electrode surface utilized for hydrogen peroxide generation, and facilitates extraction of the generated hydrogen peroxide, resulting in improved performance compared to the configurations already known from the art.
  • Such an apparatus enables the generation of hydrogen peroxide at the point of use, using only readily available substances such as oxygen (from the air), and water. This has numerous advantages over purchasing bulk hydrogen peroxide, including supply security, CO2 neutrality and safety.
  • FIG. 1 is a schematic representation of a portion of the apparatus of the present invention, exhibiting an electrically conductive porous gas transport layer along with components of a membrane-electrode assembly, in accordance with an embodiment of the present invention.
  • FIG. 2 is a schematic view of a design for an electrochemical cell, in accordance with another embodiment of the present invention.
  • FIG. 3 is a further schematic view of a configuration for an electrochemical cell design, in accordance with yet another embodiment of the present invention.
  • FIG. 4 is an exploded view of the electrochemical cell design of figure 1.
  • FIG. 5 is a flow representation of a method for making hydrogen peroxide while employing the apparatus of the present invention.
  • the phrase “electrochemical cell,” refers to, for example, a device that includes at least a positive electrode, a negative electrode, and an electrolyte therebetween which conducts ions (e.g., H+ ) but electrically insulates the positive and negative electrodes.
  • the device may include multiple positive electrodes and/or multiple negative electrodes enclosed in one container.
  • the phrase “positive electrode,” refers to the electrode from which positive ions, e.g. H+ , conduct, flow or move.
  • the phrase “negative electrode” refers to the electrode towards which positive ions, e.g. , H+ , flow or move during discharge of the electrochemical cell.
  • the application of heat and pressure ensures that the cathode and membrane are physically attached and the anode and the membrane are physically attached.
  • electrolyte refers to an electrolyte in the form of a cation exchange membrane, for example Nafion, which allows ions, e.g., H+ , to migrate there through but which does not allow electrons to conduct therethrough
  • direct contacts refers to the juxtaposition of two materials such that the two materials contact each other sufficiently to conduct either an ionic or electronic current.
  • direct contact refers to two materials in physical contact with each other and which do not have any third material positioned between the two materials which are in direct contact.
  • porous refers to a material that includes pores, e.g., nanopores, mesopores, or micropores.
  • making refers to the process or method of forming or causing to form the object that is made.
  • making an energy storage electrode includes the process, process steps, or method of causing the electrode of an energy storage device to be formed.
  • the end result of the steps constituting the making of the energy storage electrode is the production of a material that is functional as an electrode.
  • providing refers to the provision of, generation or, presentation of, or delivery of that which is provided.
  • solvent refers to a liquid that is suitable for dissolving or solvating a component or material described herein.
  • a solvent includes a liquid, e.g., toluene, which is suitable for dissolving a component, e.g., the binder, used in the garnet sintering process.
  • water oxidation reaction refers to a reaction such as
  • Alternative anode reactions include water oxidation to hydrogen peroxide or ozone, hydrogen oxidation or oxidation of alcohols.
  • oxygen reduction reaction refers to a reaction such as 2O 2 + 4H + + 4e ⁇ - ⁇ 2H 2 O 2
  • Oxygen sources include air, oxygen generated on site (for example through a pressure swing adsorption system), and oxygen gas cylinders.
  • the apparatus of the present invention comprises a plurality of electrochemical cells, each electrochemical cell 1 comprising at least an electrode assembly 4.
  • the electrode assembly 4 may be a membrane electrode assembly.
  • the membrane electrode assembly comprises electrodes at which electrochemical reactions take place.
  • the membrane electrode assembly comprises in its most general configuration of an anode, a cation exchange membrane, and a cathode that are in contact with each other. Distinct from configurations known from the art, in the configuration proposed by the present invention, no porous ionically conductive layer is present between the cation exchange membrane and cathode.
  • the anode acts as a proton source for the cathode, and while water is the most common electrolyte reactant, other electrolytes (proton sources) such as alcohols (e.g. methanol, ethanol) or molecular hydrogen are envisioned to be used in accordance with the present invention. If alternative proton sources to water are used, the overall cell reaction and half-cell reaction are modified as needed.
  • proton sources such as alcohols (e.g. methanol, ethanol) or molecular hydrogen are envisioned to be used in accordance with the present invention. If alternative proton sources to water are used, the overall cell reaction and half-cell reaction are modified as needed.
  • Anodes for water oxidation to oxygen are well-known to those versed in the art. These typically consist of iridium oxide nanoparticles deposited directly on a polymer exchange membrane or a current collector, forming the anode catalyst layer 16.
  • the ion exchange membrane 15 or polymer exchange membrane 15 should be a proton conducting membrane, exemplarily a NafionTM ion exchange membrane.
  • the thickness of the membrane is between 10 pm to 1500 pm, preferably between 100 and 500 pm.
  • the anode current collector 17 may comprise a Titanium layer or a Titanium felt, with thickness ranging from 50 pm to 3000 pm.
  • the layer or felt comprises porosity to allow an escape path for the oxygen gas generated at the anode catalyst layer 16.
  • the sintered Titanium layer or Titanium felt can also be coated with other materials, such as Platinum or Gold, to improve electrical contact.
  • Iridium oxide nanoparticles can be combined or replaced with ruthenium oxide, platinum and other metals. Deposition of the nanoparticles occurs via spray coating, tape casting and other suitable methods, and it can take place directly at the polymer exchange membrane 15, forming a catalyst coated membrane (CCM) 15 or at the current collector 17, forming a GDE.
  • CCM catalyst coated membrane
  • the polymer exchange membrane 15 and the sintered Titanium layer or Titanium felt 17 can be attached to each other in a manner that the anode catalyst layer 16 is located in between.
  • the attachment can be mediated by the application of ionomer solution, and the application of heat and/or pressure.
  • the oxygen may be sourced from air, an oxygen concentrator or from a cylinder of compressed gas.
  • Cathodes consist of a cathode catalyst layer 14 and a cathode gas diffusion layer 13, layers 13 and 14 are in contact with each other.
  • the cathode gas diffusion layer 13 is porous and made of an electrically conducting material to enable transport of oxygen, water and hydrogen peroxide to/from the cathode catalyst layer 14.
  • the cathode gas diffusion layer 13 consists of carbon cloth or fibers.
  • Other suitable cathode gas diffusion layers include metallic foams or meshes, for example made of Titanium or other metals, or other electrically conductive foams such as reticulated vitreous carbon (RVC) or graphene oxide.
  • RVC reticulated vitreous carbon
  • the thickness of the cathode gas diffusion layer is between 0.05 mm to 10 mm, preferably between 0.1 to 5 mm, even more preferably between 0.5 to 2 mm.
  • the cathode gas diffusion layer 14 can be coated on either one or both sides with PTFE or other materials, to modify its properties.
  • the cathode catalyst layer 14 contains the catalyst where the electrochemical reaction takes place, and it is placed between the cathode gas diffusion layer 13 and the ion polymer exchange membrane 15.
  • a catalyst ink may be deposited onto the cathode gas diffusion layer 13, forming a gas diffusion electrode.
  • the catalyst ink contains ionomer and a catalyst, mixed with a solvent. Typical ionomers include Nafion dispersion. Solvents include alcohols and/or water.
  • Cathode catalysts should be selective towards oxygen reduction to hydrogen peroxide, and include Pt-Hg, Pd-Hg, Cu-Hg, Ag-Hg, Ag, Au, carbon, graphene, nitrogen doped carbon, sulphur doped carbon, cobalt porphyrins and phthalocyanines, transition metal sulfides and nitrides and any combinations thereof.
  • Catalyst materials are in a nanoparticle form in order to increase surface area and facilitate deposition procedures.
  • catalyst ink is sprayed directly on the polymer exchange membrane, forming a catalyst coated membrane, with the gas diffusion layer added afterwards. It is also possible to combine both a catalyst coated membrane and a gas diffusion electrode.
  • the cathode is placed with its catalyst layer 14 facing the ion polymer exchange membrane 15.
  • it is the application of heat and pressure that ensures that the cathode and membrane are physically attached. The same is valid for the application of heat and pressure for ensuring the attachment between the anode and the membrane.
  • Typical values for temperature and pressure are 80-130 C, and 20-2000 kg/cm 2 , which are usually maintained from 2 to 20 minutes.
  • a binder material may be used to ensure the attachment of these layers.
  • the anode current collector 17 may also be pressed or bound with a binder on the opposite side of the membrane 15 in a single-step pressing.
  • the result is a single mechanical entity containing cathode and anode electrodes, as well as a polymer exchange membrane.
  • the entity is the membrane-electrode assembly (MEA) or the electrode assembly 4.
  • the electrode assembly 4 is mechanically assembled in an electrochemical cell 1, which provides the right environment in terms of current collection, gas and water delivery and peroxide extraction.
  • the components of the electrode assembly 4 and a gas transport layer 3 that is also comprised by the apparatus of the present invention as assembled are shown in the figures and discussed in more detail in connection with the figures.
  • the gas transport layer 3 must be both electrically conductive, and porous.
  • the electrochemical cell 1 in accordance with an embodiment of the present invention comprises a configuration as follows: an electrically conductive porous gas transport layer 3, placed in direct contact with the cathode side of the membrane-electrode assembly 4, and serves the dual purpose of both providing a uniform flow of oxy gen-containing gas throughout its surface, as well as serving as a current collector.
  • the electrically conductive porous gas transport layer 3 could be made by either one of aluminum, titanium, graphite, other metals or post-transition metals.
  • the porosity of the electrically conductive porous gas transport layer 3 should be adapted to overall gas flow and gas pressure.
  • Preferred pressure drop across the electrically conductive porous gas transport layer in the through-plane direction is of at least 1 mbar, and preferably above 20 mbar, and even more preferably above 30 mbar for a 400 cm 2 area.
  • Thickness of the electrically conductive porous gas transport layer is between 0.5 and 10 mm, preferably between 1 and 5 mm and even more preferably between 1 and 3 mm.
  • Pore size of the electrically conductive porous gas transport layer is between 0.1 and 100 um, preferably between 0.13 and 10 um, and even more preferably between 0.2 and 5 um.
  • the electrically conductive porous gas transport layer should cover at least 10 % of the cathode surface, preferably at least 70 % and even more preferably at least 95 %.
  • water should not penetrate inside the electrically conductive porous gas transport layer, as this would block some of the gas pathways, and oxygen would not be delivered uniformly to the cathode gas diffusion layer surface. This is prevented by the small porosity of the electrically conductive porous gas transport layer, which creates a naturally hydrophobic surface that repels water, and prevents water from entering inside the electrically conductive porous gas transport layer and saturating its pores.
  • Oxygen-containing gas flows to the cathode side of the electrode assembly 4 through the porous gas transport layer 3, going through the cathode gas diffusion layer 13 in the through-plane direction and reaches the cathode catalyst layer 14. Water flows through the cathode gas diffusion layer 13 in its in-plane direction. In this manner, the cathode has simultaneous access to oxygen containing gas, water, and electricity. The hydrogen peroxide generated at the cathode is dissolved in the flowing water, and is pushed out of the cathode catalyst layer 14. As a result, hydrogen peroxide decomposition is minimized and faradaic efficiency and throughput are improved.
  • the electrically conductive porous gas transport layer 3 provides important advantages on cell assembly and repeatability over previous designs that relied on gas dispersers, where a single gas disperser that is not assembled properly or is outside of the required tolerance could lead to cell failure.
  • another advantage is that the electrically conductive porous gas transport layer serves the dual purpose of collecting current from the cathode electrode, as well as delivering the oxygen gas reactant to the cathode electrode, while gas dispersers would typically only disperse the gas and additional components would be required for current collection.
  • At least one additional gas diffusion layer 20 is inserted between the cathode gas diffusion layer 13 and the electrically conductive porous gas transport layer 3, to facilitate water or gas transport, or favor hydrophilicity or hydrophobicity.
  • the first and last of the inserted gas diffusion layers are in contact with the electrically conductive porous gas transport layer 3 and the cathode, respectively.
  • the gas diffusion layer 13 adjacent to the electrically conductive porous gas transport layer 3 is of hydrophobic nature.
  • the gas diffusion layers could also be patterned with Teflon or other substances to have select preferential areas of hydrophobicity. These preferred hydrophobicity areas could be in-plane, or through-plane or both of the gas diffusion layer.
  • any inserted gas diffusion layers could cover an area of at least 10 % of the cathode, preferably at least 70 % and even more preferably at least 95 %.
  • the cathode gas diffusion layer should have a pore size larger than the electrically conductive porous gas transport layer to facilitate water flow through it.
  • the first and all gas diffusion layers should have a pore size between 1 and 1000 um, preferably between 50 and 1000 um and even more preferably between 100 and 1000 um.
  • the permeability of the cathode gas diffusion layer should be between 50 to 1000 L/m 2 s, preferably between 100 to 600 L/m 2 s and even more preferably between 150 and 500 L/m 2 s.
  • a cathode plate is placed on the side of the electrically conductive porous gas transport layer 3 opposite of the electrode assembly 4. Its role is to provide mechanical support and electrical contact to the electrically conductive porous gas transport layer 3 and the membrane electrode assembly 4.
  • the cathode plate is made of an electrically conductive material, such as aluminum, titanium, stainless steel or graphite. A combination of injection molded plastic and conductive material is also suitable for the cathode plate.
  • the cathode plate may have a dedicated gas inlet, and gas is directed to an internal cavity from which is homogeneously delivered to the electrically conductive porous gas transport layer 3. Similarly, the cathode plate also contains liquid inlets and outlets.
  • the cathode plate and electrically conductive porous gas transport layer 3 have inlets and outlets in the through-plane direction constituting internal manifolds.
  • the cathode plate gas cavity could have electrically conductive pillars, a coarse porous material or a mesh, that are in direct contact with the electrically conductive porous gas transport layer 3.
  • gas and liquid inlets and outlets can be incorporated in respective gaskets without affecting the nature of the invention.
  • Suitable gasket materials include PTFE, EPDM and other polymer-based substances, as well as ABS, PA and other plastics.
  • the electrically conductive porous gas transport layer could be physically attached to the cathode housing, by means for example of soldering or welding. In some other embodiments, the electrically conductive porous gas transport layer 3 and the cathode housing are simply pressed against each other during assembly. An O-ring, gasket or sealant products can be used between the two in order to prevent gas leakage.
  • An anode chamber collecting electrical current from the electrode assembly, and contains the inputs and outputs to the anode side of the electrode assembly may also be part of the apparatus of the present invention.
  • the anode chamber contains an anode input and an anode output.
  • the anode input serves to introduce water inside the anode chamber, and the output directs excess water not consumed by the anode and oxygen gas generated during the electrochemical reaction outside of the housing.
  • the anode chamber may be in electrical contact with the anode side of the electrode assembly 4. This can be facilitated by pillars or other structures that allow water flow through, while at the same time being in direct contact with the anode. In other embodiments, porous metals or mesh structures could also be used as a separate component.
  • the cathode and anode plates may be treated as a single piece, a bipolar plate.
  • oxygen-containing gas is introduced at the cathode with a flow between 0.01 to 100 mL/min/cm 2 of electrode area, to obtain a pressure between 0.01 and 10 bar.
  • the source of oxygen-containing gas may be one of ambient air, a pressurized oxygen bottle or an oxygen concentrator.
  • Water is introduced to the anode with a water flow between 0.01 to 50 ml/min/cm 2 of electrode area.
  • the water used is deionized, with a conductivity under 20 pS/cm, and even more preferably with a conductivity under 1 pS/cm. This flow can be continuous or pulsating so as to only refill the anode compartment periodically.
  • Water is also introduced at the cathode chamber in a suitable flow, typically between 0.01 to 50 ml/min/cm 2 of electrode area.
  • Voltage is applied between the cathode and anode electrodes, between 0.6 and 10 V per cell, preferably between 1.2 and 5 V and even more preferably between 1.2 and 3.5 V.
  • Current from the cell ranges between 20 mA/cm 2 to 1500 mA/cm 2 . This results in hydrogen peroxide being generated at the cathode.
  • the generated concentration is between 200 mg/L to 200000 mg/L, preferably between 1000 to 30000 mg/L.
  • the output concentration can be varied depending on the applied current and the water flow in the cathode chamber. It is also possible to combine one or more cells in series, in parallel or a combination of both to generate higher throughputs.
  • the generated hydrogen peroxide solution can be stored in a reservoir for subsequent use or be directly injected in a pipe. Examples of suitable uses are within wastewater treatment, irrigation water treatment or cooling tower water treatment, or any other applications where hydrogen peroxide is used as an oxidant, biocide and / or oxygen source.
  • Generated hydrogen peroxide can also be combined with UV light, Fenton-like agents (such as iron ions) or ozone to create OH radicals, which have a higher oxidation potential and are the basis for advanced oxidation processes. It can also be combined with acetic acid on-site to generate peracetic acid.
  • Several of the electrochemical cells in this configuration can be arranged in parallel or series, which would enable a higher overall throughput. A particularly attractive arrangement is a series connection between cell in a compact fashion, also called a stack or stacking.
  • each electrochemical cell 1 comprises an electrode assembly 4 comprising at least one cathode gas diffusion layer 13, at least one cathode catalyst layer 14, at least one ion exchange membrane 15, at least one anode catalyst layer 16, and at least one anode current collector 17.
  • the at least one cathode catalyst layer 14, the at least one ion exchange membrane 15 and the at least one anode catalyst layer 16 are disposed neighboring each other within the electrode assembly 4, being disposed in succession along an horizontal axis of the membrane electrode assembly 4.
  • the electrochemical cell 1 also comprises at least one electrically conductive gas transport layer 3 disposed neighboring the cathode gas diffusion layer 13, the gas transport layer 3 being capable of facilitating a flow of oxy gen-containing gas towards the cathode gas diffusion layer 13 and being capable of current collection.
  • the cathode gas diffusion layer 13 contains water, which is preferably flowing.
  • the cathode catalyst layer 14 comprised by the apparatus of the present invention comprises one or a plurality of catalysts
  • the anode catalyst layer 16 comprised by the apparatus of the present invention comprises as well one or a plurality of catalysts.
  • a first side of the ion exchange membrane 15 is bound against a second side of the cathode catalyst layer 14 and the anode catalyst layer 16 is bound against a second, opposing side of the ion exchange membrane 15.
  • At least one gas transport layer 3 is an electrically conductive porous gas transport layer 3 that is in direct contact with a first side of cathode gas diffusion layer 13.
  • the configuration of the apparatus permits water comprised in the cathode gas diffusion layer 13 to flow in an in-plane direction in the cathode gas diffusion layer 13.
  • the surface of the gas diffusion layer 13 (or additional gas diffusion layer 20) adjacent to gas transport layer 3 is covered at least in proportion of 10 % with the gas transport layer 3, preferably at least 70 % and even more preferably at least 95 %.
  • a porosity of the electrically conductive porous gas transport layer 3 is between about 0,1 micrometers and 100 micrometers.
  • a pressure drop induced by the electrically conductive porous gas transport layer 3 between a gas cavity from which the oxygencontaining gas is sourced and the cathode gas diffusion layer 13 is of at least 1 mbar, preferably at least 20 mbar and even more preferably 100 mbar.
  • the electrically conductive porous gas transport layer 3 comprises one of porous transition metals, post-transition metals, carbon comprising materials or a combination thereof.
  • the current density at the membrane electrode assembly 4 is between about 30 mA/cm 2 and 900 mA/cm 2 .
  • a voltage applied between the at least one cathode catalyst layer 14 and the at least one anode catalyst layer 16 is between about 1.2 and about 3.5 V.
  • FIG. 1 is a schematic representation a portion of the apparatus of the present invention, exhibiting an electrically conductive porous gas transport layer, along with components of a membrane-electrode assembly, in accordance with an embodiment of the present invention.
  • the apparatus of figure 1 comprises the electrically conductive porous gas transport with the membrane-electrode assembly, while with numeral 3 is indicated the electrically conductive porous gas transport layer, with numeral 13 is indicated the cathode gas diffusion layer, with numeral 14 is indicated the cathode catalyst layer, with numeral 15 is indicated the polymer exchange membrane, with numeral 16 is indicated the anode catalyst layer and with numeral 17 is indicated the anode current collector.
  • the electrically conductive porous gas transport layer delivers gas to the cathode gas diffusion layer, while at the same time serving as the cathode current collector.
  • the cathode gas diffusion layer has a water flow in the in-plane direction, as indicated by the arrow, and gas bubbles from the electrically conductive porous gas transport layer navigate through the water to reach the cathode catalyst layer.
  • the cathode catalyst layer reduces oxygen to hydrogen peroxide, which rapidly exits the catalyst layer and dissolves in the water flowing through the cathode gas diffusion layer.
  • the anode catalyst layer oxidizes water into protons, which cross the polymer exchange membrane to reach the cathode catalyst layer.
  • the anode current collector provides electrical signal to the anode catalyst layer.
  • FIG. 2 is a schematic view of a design for an electrochemical cell, in accordance with another embodiment of the present invention.
  • the apparatus of figure 2 comprises an electrochemical cell, while with numeral 1 is indicated the electrochemical cell, with numeral 2 is indicated the cathode plate, with numeral 3 is indicated the electrically conductive porous gas transport layer, with numeral 4 is indicated the membrane electrode assembly, with numeral 5 is indicated the anode chamber, with numeral 6 is indicated the gas inlet, with numeral 7 is indicated the cathode water inlet, with numeral 8 is indicated the cathode water, oxygen and peroxide outlet, with numeral 9 is indicated the anode input and with numeral 10 is indicated the anode output.
  • Oxy gen-containing gas is introduced through the gas inlet, and goes through the electrically conductive porous gas transport layer to be dispersed homogeneously over the cathode side of the membrane electrode assembly.
  • Water is inserted through the cathode water inlet, and flows in the in-plane direction of the cathode gas diffusion layer. Excess gas, water and hydrogen peroxide exit through the cathode outlet. Water is also inserted through the anode input to enter the anode chamber, where it is oxidized to oxygen, and excess water exits through the anode output. A voltage difference is applied between the anode and cathode sides of the membrane electrode assembly.
  • FIG. 3 is a further schematic view of a configuration for an electrochemical cell design, in accordance with yet another embodiment of the present invention.
  • the apparatus of figure 3 comprises an electrochemical cell, while with numeral 1 is indicated the electrochemical cell, with numeral 2 is indicated the cathode plate, with numeral 3 is indicated the electrically conductive porous gas transport layer, with numeral 4 is indicated the membrane electrode assembly, with numeral 5 is indicated the anode chamber, with numeral 6 is indicated the gas inlet, with numeral 9 is indicated the anode water inlet and with numeral 10 is indicated the anode water outlet.
  • the cathode water inlet 11 and the cathode outlet 12 are placed through the electrically conductive porous gas transport layer, as indicated by the dotted lines.
  • Oxy gen-containing gas is introduced through the gas inlet, and is directed through dedicated openings towards the electrically conductive porous gas transport layer to be dispersed homogeneously over the cathode side of the membrane electrode assembly.
  • Water is inserted through the cathode water inlet, passes through dedicated paths through the cathode plate and the electrically conductive porous gas transport layer and flows in the in-plane direction of the cathode gas diffusion layer. Excess gas, water and hydrogen peroxide exit through the cathode outlet. Water is also inserted through the anode input to enter the anode chamber, where it is oxidized to oxygen, and excess water exits through the anode output. A voltage difference is applied between the anode and cathode sides of the membrane electrode assembly.
  • FIG. 4 is an exploded view of the electrochemical cell design of figure 1.
  • the apparatus of figure 4 comprises an electrochemical cell, while with numeral 1 is indicated the electrochemical cell, with numeral 2 is indicated the cathode plate, with numeral 3 is indicated the electrically conductive porous gas transport layer, with numeral 4 is indicated the membrane electrode assembly, with numeral 5 is indicated the anode chamber, with numeral 18 is indicated the cathode end plate, with numeral 19 is indicated the cathode current collector, with numeral 20 is indicated one or more additional cathode gas diffusion layers, with numeral 21 is indicated the anode gasket and with numeral 22 is indicated the anode end plate. It has been found, that one or even more additional cathode gas diffusion layers significantly improves the performance of the cell.
  • FIG. 5 is a flow diagram of the method comprised in the present application, while with numeral 1 is indicated the electrochemical cell, with numeral 23 the cathode pump, controlling the water flow to the cathode, with numeral 24 the gas pump, oxygen concentrator or air compressor delivering gas to the electrochemical cell, with numeral 25 the cathode outlet containing water, gas and hydrogen peroxide, with numeral 26 the anode pump, with numeral 27 the anode outlet, with numeral 28 the power supply and with numeral 29 the hydrogen peroxide sensor.
  • the hydrogen peroxide sensor measures concentration at the outlet, which is used to automatically regulate the flow delivered by the cathode pump 23 and the current at the power supply in keeping a constant concentration.
  • the anode of the electrochemical cell 1 is prepared by depositing Iridium oxide nanoparticles on a cation polymer exchange membrane.
  • the thickness of the polymer exchange membrane is 135 pm, but thicker or thinner membranes may also be used without affecting the resulting abilities of the electrochemical cell.
  • the membrane is between 5 and 500 pm in thickness and more preferably between 20 and 200 pm.
  • a current collector is placed on the anode side of the membrane in direct contact with the iridium oxide nanoparticles.
  • the material of the current collector is selected to withstand oxidizing conditions and is preferably Titanium and/or its oxides, tantalum and/or its oxides, gold, carbon, stainless steel or platinum, among others.
  • the current collector material may also be an electrically conducting material, coated with platinum, iridium and its oxides, titanium and its oxides or tantalum and its oxides. The purpose of this coating is to obtain suitable electrical contact to the anode catalyst, which could be facilitated by the application of pressure and/or temperature during the cell fabrication process.
  • a Titanium felt was used as an anode current collector.
  • the cathodes were obtained by coating a gas diffusion layer with a suitable catalyst material.
  • Gas diffusion layers could be hydrophilic or hydrophobic and contain coatings of PTFE or other substances in order to control the hydrophobicity.
  • Coating was done by dispersing suitable catalyst nanoparticles in ethanol, water and ionomer to form a catalyst ink, which can then be sprayed or deposited by other means onto the gas diffusion layer.
  • Suitable cathode catalysts should be selective towards oxygen reduction to hydrogen peroxide, and include Pt-Hg, Pd-Hg, Cu-Hg, Ag-Hg, Ag, Au, carbon, graphene, nitrogen doped carbon, Sulphur doped carbon, Cobalt porphyrins and phthalocyanines, transition metal sulfides and nitrides and any combinations thereof.
  • the membrane electrode assembly was placed in a suitable cell housing, as shown in Figure 2.
  • the cell housing consists of an anode chamber, where the anode side of the cell is placed, an electrically conductive porous gas transport layer, where the cathode side of the cell is placed, and a cathode housing that provides mechanical support for the electrically conductive porous gas transport layer.
  • the electrically conductive porous gas transport layer is flat, and that it homogeneously contacts the cathode gas diffusion layer. This is very important as any deviations would facilitate water escaping from the desired path in-plane of the cathode gas diffusion layer, and taking a path outside of it as it offers less resistance and pressure drop. This would result in a lower efficiency in the removal of hydrogen peroxide from the cathode catalyst layer, and overall lower performance of the electrochemical cell.
  • the cathode side of the cell is fed with a gas flow of 22 ml/min/cm 2 , normalized to electrode area, with a preferred range of 0.01 to 100 mL/min/cm 2 .
  • the pressure at the cathode is set between 0.01 and 10 bar.
  • the anode was fed a water flow at 0.3 ml/min/cm 2 , normalized to electrode area and can be varied in the range of 0.01 to 50 ml/min/cm 2 .
  • Water was also fed in between the cathode electrode and the ion exchange membrane in a suitable flow to produce a hydrogen peroxide concentration of 1000 to 3000 mg/L, and preferably the concentration can be set between 200 mg/L to 50000 mg/L, even more preferably between 5000 to 30000 mg/L.
  • the current density was set to 100 mA/cm 2 but can preferably be set in the range of 10 to 500 mA/cm 2 .
  • the potential corresponding to the 100 mA/cm 2 was measured to 1.9 V.

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Abstract

La présente invention concerne un appareil de production de peroxyde d'hydrogène, comprenant une ou plusieurs cellules électrochimiques, l'appareil comprenant en outre au moins une couche de transport de gaz poreuse électriquement conductrice disposée à côté d'une couche de diffusion de gaz de cathode, la couche de transport de gaz étant conçue pour distribuer un flux de gaz contenant de l'oxygène vers la couche de diffusion de gaz de cathode et étant conçue pour collecter du courant, et comprenant de l'eau qui doit s'écouler à travers la couche de transport de gaz poreuse.
EP22830454.9A 2021-12-06 2022-12-04 Appareil et procédé de production de peroxyde d'hydrogène Pending EP4399346A1 (fr)

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Application Number Priority Date Filing Date Title
EP21212606.4A EP4190943A1 (fr) 2021-12-06 2021-12-06 Cellule électrochimique améliorée pour la réduction de l'oxygène en peroxyde d'hydrogène
US17/889,599 US20240060195A1 (en) 2022-08-17 2022-08-17 Apparatus and method for producing hydrogen peroxide
PCT/EP2022/084324 WO2023104680A1 (fr) 2021-12-06 2022-12-04 Appareil et procédé de production de peroxyde d'hydrogène

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US5972196A (en) 1995-06-07 1999-10-26 Lynntech, Inc. Electrochemical production of ozone and hydrogen peroxide
US5770033A (en) 1993-07-13 1998-06-23 Lynntech, Inc. Methods and apparatus for using gas and liquid phase cathodic depolarizers
US7892408B2 (en) 2007-11-06 2011-02-22 Lynntech, Inc. Cathodic electrocatalyst layer for electrochemical generation of hydrogen peroxide
US9551076B2 (en) 2011-05-31 2017-01-24 Clean Chemistry, Inc. Electrochemical reactor and process
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