WO2022226589A1 - Capture électrochimique de dioxyde de carbone et production de minéral de carbonate - Google Patents

Capture électrochimique de dioxyde de carbone et production de minéral de carbonate Download PDF

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WO2022226589A1
WO2022226589A1 PCT/AU2022/050385 AU2022050385W WO2022226589A1 WO 2022226589 A1 WO2022226589 A1 WO 2022226589A1 AU 2022050385 W AU2022050385 W AU 2022050385W WO 2022226589 A1 WO2022226589 A1 WO 2022226589A1
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gas permeable
gas
permeable cathode
mineral
liquid
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Chong-Yong Lee
Gordon George Wallace
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University Of Wollongong
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    • 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
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    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • C—CHEMISTRY; METALLURGY
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/60—Preparation of carbonates or bicarbonates in general
    • C—CHEMISTRY; METALLURGY
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    • 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
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    • C25B1/26—Chlorine; Compounds thereof
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    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
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    • 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
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/069—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of at least one single element and at least one compound; consisting of two or more compounds
    • 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
    • C25B15/083—Separating products
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    • 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
    • C25B15/087—Recycling of electrolyte to electrochemical cell
    • 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
    • C—CHEMISTRY; METALLURGY
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    • 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
    • C25B1/14—Alkali metal compounds
    • 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
    • C25B1/18—Alkaline earth metal compounds or magnesium compounds
    • 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
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

  • the embodiments described herein broadly relate to electrochemical mineral carbonation cells and the electrochemical capture of carbon dioxide, and particularly to electrochemical capture of carbon dioxide and production of carbonate mineral.
  • Example embodiments relate to electrochemical cells and electrochemical systems including electrochemical cells for capturing carbon dioxide, and to methods of electrochemically capturing carbon dioxide using electrochemical cells.
  • Carbon dioxide gas (C0 2 (g)) is accepted to have a major influence on climate, and production of CO2 needs to be reduced and existing CO2 needs to be removed from the environment.
  • C0 2 (g) Carbon dioxide gas
  • CO2 due to net global deforestation and growing demand for carbon as a resource, CO2 will otherwise continue to be emitted and accumulate in the environment. Thus, technologies for CO2 capture and utilization are required and are critically important.
  • amine- scrubbing carbon capture technology using a relatively costly capture agent, amine and it derivatives such as monoethanolamine (MEA), is approximately ten times more expensive than calcium based carbon capture agents, such as calcium chloride and calcium hydroxide.
  • the use of amine organic-based carbon capture agents also involves costly regeneration processes, expensive infrastructure, and suffers from oxidative and thermal degradation.
  • carbonate minerals are stable and abundant forms of inorganic material.
  • An electrochemical cell produces one or more chemical materials over sustained periods of time, typically for use outside of the electrochemical cell.
  • the chemical materials may be in the form of gases, liquids and/or solids.
  • currently known processes involve direct injection of gaseous CO2 into an aqueous electrolyte. Since the CO2 solubility in aqueous solution is low (0.033 M at ambient atmosphere), the kinetics of the CO2 mineralisation is a rate limiting factor and is another problem that needs to be overcome.
  • an electrochemical cell for the electrochemical capture of carbon dioxide.
  • an electrochemical cell for the electrochemical capture of carbon dioxide and the production of carbonate mineral.
  • an electrochemical system including at least one electrochemical cell, for the electrochemical capture of carbon dioxide and/or the production of carbonate mineral.
  • a method of electrochemically capturing carbon dioxide and/or the production of carbonate mineral using an electrochemical cell is an electrochemical flow cell.
  • an electrochemical mineral carbonation cell for capturing carbon dioxide, the electrochemical cell comprising a gas permeable cathode, wherein carbon dioxide gas is able to pass into an outer surface of and at least partially through the gas permeable cathode to react with a liquid catholyte.
  • An anode is provided, wherein a voltage difference is able to be applied between the gas permeable cathode and the anode.
  • a membrane is positioned between the gas permeable cathode and the anode.
  • the liquid catholyte is positioned between the gas permeable cathode and the membrane, the liquid catholyte including mineral ions, for example preferably calcium ions, sodium ions, potassium ions, and/or lithium ions, either individually or in any combination.
  • a liquid anolyte is positioned between the anode and the membrane. In operation, the liquid catholyte flows along an inner surface of the gas permeable cathode and a carbonate mineral is produced at or near the inner surface of the gas permeable cathode and is at least partially transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the liquid catholyte flows along an inner surface of the gas permeable cathode and a carbonate mineral is produced by being precipitated at the inner surface of the gas permeable cathode and the carbonate mineral is at least partially transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the carbonate mineral may be produced by being precipitated on the inner surface of the gas permeable cathode, and the carbonate mineral may be at least partially removed (from the inner surface of the gas permeable cathode) and transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the carbonate mineral that is produced by being precipitated at or on the inner surface of the gas permeable cathode is insoluble or substantially insoluble in the liquid catholyte.
  • an example carbonate mineral that is produced by being precipitated is calcium carbonate.
  • the liquid catholyte flows along an inner surface of the gas permeable cathode and a carbonate mineral is produced in solution in the liquid catholyte at the inner surface of the gas permeable cathode and the carbonate mineral is at least partially transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the carbonate mineral that is produced in solution in the liquid catholyte at the inner surface of the gas permeable cathode is soluble or substantially soluble in the liquid catholyte.
  • the soluble carbonate mineral can be produced in an aqueous form.
  • example carbonate minerals that are produced in solution in the liquid catholyte are sodium carbonate, potassium carbonate, or lithium carbonate.
  • the mineral ions can be, or can include, magnesium ions, strontium ions, and/or barium ions.
  • the produced carbonate minerals can be magnesium carbonate, strontium carbonate or barium carbonate.
  • an electrochemical system for capturing carbon dioxide comprising a stack of a plurality of electrochemical cells.
  • At least one, or each, electrochemical mineral carbonation cell comprises a gas permeable cathode, an anode, a membrane positioned between the gas permeable cathode and the anode.
  • a carbon dioxide gas source introduces carbon dioxide gas into an outer surface of and at least partially through the gas permeable cathode.
  • a power supply applies a voltage difference between the gas permeable cathode and the anode.
  • a liquid catholyte source supplies a liquid catholyte as a liquid catholyte flow between the gas permeable cathode and the membrane, the liquid catholyte including mineral ions, for example preferably calcium ions, sodium ions, potassium ions and/or lithium ions.
  • An anolyte source supplies a liquid anolyte between the anode and the membrane.
  • the liquid catholyte flows along an inner surface of the gas permeable cathode, and carbonate mineral is produced at or near the inner surface of the gas permeable cathode and is at least partially transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the carbonate mineral formed depends on the mineral ions used, for example the carbonate mineral can be calcium carbonate, sodium carbonate, potassium carbonate and/or lithium carbonate.
  • the carbonate mineral can be calcium carbonate, sodium carbonate, potassium carbonate and/or lithium carbonate.
  • calcium carbonate is insoluble or substantially insoluble and is produced as a precipitate
  • sodium carbonate, potassium carbonate and lithium carbonate are soluble or substantially soluble and are produced in solution without forming a precipitate.
  • the liquid catholyte flows along the inner surface of the gas permeable cathode, and the carbonate mineral is produced by being precipitated on the inner surface of the gas permeable cathode and the carbonate mineral is at least partially removed and transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the carbonate mineral is in the form of calcium carbonate, sodium carbonate, potassium carbonate or lithium carbonate, which are stable inorganic materials that can permanently store carbon dioxide.
  • the method including introducing carbon dioxide gas into the outer surface of the gas permeable cathode and allowing the carbon dioxide gas to pass at least partially through the gas permeable cathode to react with the liquid catholyte including mineral ions.
  • the method also includes applying a voltage difference between the anode and the gas permeable cathode, and flowing the liquid catholyte along the inner surface of the gas permeable cathode.
  • soluble carbonate mineral for example sodium carbonate, potassium carbonate or lithium carbonate
  • carbonate mineral precipitate for example calcium carbonate precipitate
  • carbonate mineral precipitate is formed on the inner surface of the gas permeable cathode, and is at least partially removed (from the inner surface of the gas permeable cathode) and transported away from the inner surface of the gas permeable cathode by the flowing liquid catholyte (i.e. by the liquid catholyte flow).
  • the carbonate mineral is in the form of sodium carbonate, potassium carbonate or lithium carbonate, which have high solubility in the liquid electrolyte (i.e. liquid catholyte) and can permanently store carbon dioxide.
  • An example method also includes introducing carbon dioxide gas into the outer surface of the gas permeable cathode and allowing the carbon dioxide gas to pass at least partially through the gas permeable cathode to react with the liquid catholyte including mineral ions.
  • the method also includes applying a voltage difference between the anode and the gas permeable cathode, and flowing the liquid catholyte along the inner surface of the gas permeable cathode.
  • the produced carbonate mineral that is soluble or substantially soluble for example sodium carbonate, potassium carbonate or lithium carbonate, is formed at, or on, the inner surface of the gas permeable cathode, and is transported away from the inner surface of the gas permeable cathode by the flowing liquid catholyte (i.e. by the liquid catholyte flow).
  • the carbon dioxide is stored, and regenerated calcium ions, sodium ions, potassium ions, or lithium ions are reused to participate in the electrochemical carbon capture process.
  • the regeneration method including a chemical reaction between calcium carbonate, sodium carbonate, potassium carbonate, or lithium carbonate and hydrochloric acid to form a mineral chloride (e.g.
  • the source of hydrochloric acid can be fully or partially derived from the anodic process within the same electrochemical cell, such as chloride oxidation, or externally from, for example, industry plants with hydrochloric acid emitted as a waste, or externally outsource chemical reagent.
  • a method and system of regenerating carbonate mineral in an electrochemical mineral carbonation cell to capture carbon dioxide Carbon dioxide gas is introduced into an outer surface of a gas permeable cathode, and the carbon dioxide gas is allowed to pass at least partially through the gas permeable cathode to react with a liquid catholyte including mineral ions, for example calcium ions, sodium ions, and/or potassium ions, either individually or in any combination.
  • the liquid catholyte is positioned between an inner surface of the gas permeable cathode and a membrane, the membrane positioned between the gas permeable cathode and an anode, and a liquid anolyte positioned between the anode and the membrane.
  • a voltage difference is applied between the anode and the gas permeable cathode.
  • the liquid catholyte flows along the inner surface of the gas permeable cathode.
  • the liquid anolyte flows along an inner surface of the anode.
  • Carbonate minerals such as calcium carbonate, sodium carbonate, potassium carbonate and/or lithium carbonate are produced or formed, as precipitated material or soluble material, at, near or on the inner surface of the gas permeable cathode.
  • the carbonate mineral is at least partially transported away from the inner surface of the gas permeable cathode by the flowing liquid catholyte (i.e. by the liquid catholyte flow).
  • the mineral ions are regenerated in the liquid catholyte by reacting at least some of the carbonate mineral that has been transported with hydrochloric acid or chlorine gas to form mineral chloride in solution in water.
  • the hydrochloric acid can be produced at the anode.
  • the regeneration also includes storing released CO2 gas when forming the mineral chloride in solution in water.
  • Figure 1 illustrates an example electrochemical mineral carbonation cell with a gas permeable cathode to produce carbonate mineral.
  • Figure 2 illustrates example processes occurring at or in the vicinity of the gas- phase, solid-phase and liquid-phase interface of the example electrochemical mineral carbonation cell illustrated in Figure 1.
  • Figure 3 illustrates another example electrochemical mineral carbonation cell with a gas permeable cathode to produce carbonate mineral.
  • the anode is a gas permeable anode, and a produced gas, for example hydrogen gas, can be transferred from a cathodic compartment to an anodic compartment.
  • Figure 4 illustrates a flowchart of an example electrochemical process of the production of a carbonate mineral from aqueous mineral ions in the presence of CO2.
  • Figure 5 illustrates a flowchart of an example electrochemical process of the production of calcium carbonate from aqueous calcium ions in the presence of CO2.
  • Figure 6 is a schematic diagram showing electrochemically generated carbonate mineral accumulating on the surface of a gas permeable cathode in a static liquid electrolyte (i.e. catholyte).
  • a static liquid electrolyte i.e. catholyte
  • Figure 7 is a schematic diagram showing electrochemically generated carbonate mineral not accumulating on the surface of a gas permeable cathode in an electrolyte flow (i.e. a catholyte flow) (contrasted to Figure 6).
  • Figure 8 is a schematic diagram showing electrochemically generated carbonate mineral not accumulating on the surface of a gas permeable cathode in an alternating electrolyte flow (i.e. an alternating catholyte flow) (contrasted to Figure 6).
  • Figure 9 illustrates an example stack of electrochemical mineral carbonation cells including multiple electrochemical cell units to capture carbon dioxide as carbonate mineral.
  • Each electrochemical cell includes a gas permeable cathode.
  • the configuration represents individually independent and separable electrochemical cells.
  • Figure 10 illustrates another example stack of electrochemical mineral carbonation cells including multiple electrochemical cell units to capture carbon dioxide as carbonate mineral.
  • Each electrochemical cell includes a gas permeable cathode.
  • the configuration represents an integrated stack configuration including each cathodic or anodic compartment sharing the same current collector.
  • Figure 11 illustrates another example stack of electrochemical mineral carbonation cells including multiple electrochemical cell units to capture carbon dioxide as carbonate mineral.
  • the configuration represents an integrated stack configuration including each cathodic or anodic compartment sharing the same current collector.
  • Each electrochemical cell includes a gas permeable cathode.
  • the anodic compartment of each electrochemical cell also includes a gas permeable anode.
  • Figure 12 illustrates an example electrochemical system including a stack of electrochemical mineral carbonation cells with gas permeable cathodes and associated example components to capture carbon dioxide as carbonate mineral, and mineral-sorbent regeneration process.
  • Figure 13 illustrates part of an example electrochemical system including a stack of electrochemical mineral carbonation cells with gas permeable cathodes (to capture carbon dioxide as carbonate mineral) and gas permeable anodes (where hydrogen oxidation reaction is taking place that used to produce acid at anode, which the acid is employable to regenerate CO2.
  • Figure 14 shows a representative SEM image of calcium carbonate produced and collected from an example electrochemical mineral carbonation cell including a gas permeable cathode.
  • Figure 15 shows representative XRD and Raman spectroscopies confirming the formation of high purity calcium carbonate from an example electrochemical mineral carbonation cell including a gas permeable cathode.
  • Figure 16 shows representative Raman spectrum confirming the formation of lithium carbonate from an example electrochemical mineral carbonation cell including a gas permeable cathode.
  • Embodiments relate to electrochemical cells and electrochemical systems for the electrochemical capture of carbon dioxide, and for the production of a carbonate mineral, preferably for the production of sodium carbonate, potassium carbonate, lithium carbonate or calcium carbonate, and to methods of electrochemically capturing carbon dioxide and preferably to the production of carbonate mineral using an electrochemical cell.
  • the electrochemical cell is an electrochemical flow cell, meaning that liquid electrolyte in the electrochemical cell is flowing or moving past one or more electrodes in the electrochemical cell.
  • gas permeable cathode As used herein, reference to a “gas permeable cathode”, or a “gas permeable anode” or a “gas permeable electrode”, is to be read as not needing to be made of a single material or continuous materials providing both gas permeability and acting as a conductor.
  • a gas permeable cathode/anode/electrode can be formed of separate components or separate layers that are joined together, such as providing a laminate structure, or positioned adjacent each other, or provided as a contiguous layered structure.
  • a gas permeable cathode/anode/electrode can be provided as a gas diffusion electrode (GDE), or as a layered structure which includes separate conducting and non conducting layers, such as including a non-conducting polymeric gas permeable membrane provided as a layer of the gas permeable cathode/anode/electrode with a separate conducting layer provided.
  • GDE gas diffusion electrode
  • a layered structure which includes separate conducting and non conducting layers, such as including a non-conducting polymeric gas permeable membrane provided as a layer of the gas permeable cathode/anode/electrode with a separate conducting layer provided.
  • reference to the electrolyte preferably a liquid electrolyte
  • reference to CO2 gas is to be read as a reference to pure CO2 gas or any gas mixture containing CO2 gas at any level of concentration and with any combination of other gas or gases.
  • reference to a flow of CO2 gas is to be read as a reference to a flow of pure gas or gas mixture including CO2 gas at some level of greater than 0 % up to 100% by volume.
  • reference to CO2 gas includes but is not limited to ambient air, compressed air, industry waste gas containing CO2, pure CO2, and intentional or unintentional prepared gas mixtures containing CO2.
  • carbonate mineral and “mineral carbonate” are intended to have the same meaning and are therefore interchangeable terms.
  • an electrochemical cell that (directly or indirectly) produce a carbonate mineral (for example as a product, or by-product) may also be referred to as an "electrochemical mineral carbonation cell".
  • the one or more type of carbonate mineral produced in these embodiments may be soluble or insoluble.
  • Embodiments also relate to methods to capture CO2, to produce carbonate mineral, and for regeneration of a carbon dioxide (CO2) capture agent or sorbent.
  • electrochemical-driven carbonate mineral for example sodium carbonate Na 2 C0 3 , potassium carbonate K2CO3, lithium carbonate L ⁇ CCE or calcium carbonate CaCCE
  • Example embodiments relate to efficient processes including introducing gaseous CO2 (or a gaseous mixture including CO2) via a gas permeable cathode, for example a gas diffusion electrode (GDE) which can be provided with a catalyst, for example as a catalyst layer, or for example a gas permeable membrane with an integrated conductive catalyst, so as to interact with the catalyst and with liquid-phase mineral ions within an electrolyte, and to thereby produce carbonate mineral, either in solution or as precipitated carbonate mineral.
  • GDE gas diffusion electrode
  • the operating electrochemical system includes a stack of integrated electrochemical cells.
  • the process produces, and optionally collects, soluble or precipitated carbonate mineral, preferably continuously, and preferably additionally the regeneration of the CO2 capture agent or sorbent, being liquid- phase mineral ions within the electrolyte.
  • the mineral ions are calcium ions, sodium ions, potassium ions, lithium ions, magnesium ions, strontium ions and/or barium ions.
  • the carbonate mineral is calcium carbonate (when calcium ions are utilised), sodium carbonate (when sodium ions are utilised), potassium carbonate (when potassium ions are utilised), lithium carbonate (when lithium ions are utilised), magnesium carbonate (when magnesium ions are utilised), strontium carbonate (when strontium ions are utilised) and/or barium carbonate (when barium ions are utilised).
  • the mineral ions are calcium ions and the carbonate mineral is calcium carbonate.
  • the mineral ions are sodium ions and the carbonate mineral is sodium carbonate.
  • the mineral ions are potassium ions and the carbonate mineral is potassium carbonate.
  • the mineral ions are lithium ions and the carbonate mineral is lithium carbonate.
  • gas permeable cathode As the cathode in an electrochemical cell.
  • the gas permeable cathode can be, for example, a gas diffusion electrode (GDE), most preferably provided with a catalyst or catalyst layer, or a non- conductive polymeric gas permeable membrane provided with an integrated conductive catalyst or a conductive catalyst layer.
  • GDE gas diffusion electrode
  • the gas permeable cathode can include a cathodic catalyst layer that is conductive.
  • the gas permeable cathode can include a cathodic catalyst layer that is provided on or adjacent a separate conductive material layer, for example a conductive material (e.g. a metal) that is deposited on or positioned adjacent a non-conductive polymeric gas permeable membrane of the gas permeable cathode.
  • Example non-conductive polymeric gas permeable membrane materials include polytetrafluoroethylene (PTFE), polyethylene (PE) and polypropylene (PP).
  • the gas permeable cathode is in contact with an electrolyte containing mineral ions, preferably though not necessarily containing calcium ions, sodium ions, potassium ions, and/or lithium ions which provides an excellent solid-liquid interface so that CO2 gas, supplied either as pure CO2 gas or as a gaseous mixture including CO2 gas, can be introduced to participate in the mineral carbonation reaction by passing through the gas permeable cathode to interact with the electrolyte.
  • the flow of CO2 gas through the gas permeable cathode offers an improved and continuous supply pathway of the reactant (CO2 gas) for the mineral carbonation process.
  • gas permeable cathode can also be provided with a catalyst, for example as a catalyst layer, in contact with the electrolyte.
  • Reducing the cost of a regeneration process for the carbon capture agent or sorbent that is used is another problem that needs to be overcome.
  • the inventors have also developed an integrated electrochemical process for mineral ions regeneration, for example calcium, sodium, potassium or lithium ions regeneration, at room temperature to reduce the cost of the regeneration process for the carbon capture agent or sorbent (e.g. as calcium ions, sodium ions, potassium ions or lithium ions in the electrolyte).
  • a method including the steps of introducing CO2 gas, or a gas mixture containing CO2 gas, through or via the gas permeable cathode, for example being a gas diffusion electrode (GDE) provided with a catalyst layer, or a gas permeable membrane provided with an integrated conductive catalyst, to an electrolyte-cathode interface, so as to participate in the formation of carbonate mineral.
  • GDE gas diffusion electrode
  • a gas permeable membrane provided with an integrated conductive catalyst
  • any reference to CO2 gas passing into and through the gas permeable cathode means the CO2 gas passes into and at least partially through (i.e. internal to) the gas permeable cathode.
  • a gas permeable cathode/anode/electrode can be provided as a gas diffusion electrode (GDE) or as a layered structure which includes a non-conducting gas permeable membrane as a non-conductive layer and one or more separate conductive layers.
  • GDE gas diffusion electrode
  • a gas permeable cathode (or a gas permeable anode) could be formed by, for example:
  • a conformal conductive catalyst layer on or adjacent a non-conductive gas permeable membrane, typically a non- conductive polymeric gas permeable membrane, such as a porous PFTE membrane.
  • a conductive (current collector) layer on a non- conductive gas permeable membrane, typically a non-conductive polymeric gas permeable membrane, such as a porous PFTE membrane, and depositing or positioning a catalyst layer on or adjacent the conductive layer.
  • a conductive (current collector) layer on a non- conductive gas permeable membrane, typically a non-conductive polymeric gas permeable membrane, such as a porous PFTE membrane, and depositing or positioning a catalyst layer on or adjacent the conductive layer.
  • GDE gas diffusion electrode
  • FIG. 1 illustrates a configuration of an example electrochemical cell 100.
  • the electrochemical cell 100 is an electrochemical flow cell, meaning the electrolyte flows past an electrode in the electrochemical cell.
  • Gas permeable cathode 110 is preferably liquid-impermeable so as to contain liquid electrolyte, i.e.
  • liquid catholyte although liquid electrolyte can penetrate gas permeable cathode 110 to a certain extent which may improve liquid-gas phase electrochemical interaction.
  • gas permeable membrane materials include polytetrafluoroethylene (PTFE), polyethylene (PE) and polypropylene (PP).
  • Gas permeable cathode 110 includes a cathodic catalyst layer 120, i.e. a catalyst layer or a first catalyst, that faces and contacts liquid electrolyte, i.e. liquid catholyte 130, at a solid-liquid-gas interface layer 125.
  • a cathodic catalyst layer 120 i.e. a catalyst layer or a first catalyst, that faces and contacts liquid electrolyte, i.e. liquid catholyte 130, at a solid-liquid-gas interface layer 125.
  • Cathodic catalyst layer 120 can be provided as part of gas permeable cathode 110 by conventional means, for example by being deposited on the surface of or joined to another layer, such as a non-conductive polymeric gas permeable membrane (if the catalyst is itself conductive or part of a conductive mixture) or a conductive support layer provided on the non-conductive polymeric gas permeable membrane, in which cases the cathodic catalyst layer 120 is provided as an integrated layer of overall gas permeable cathode 110.
  • Liquid catholyte 130 contains mineral ions, which in particular examples are calcium ions, sodium ions, potassium ions or lithium ions.
  • a membrane 140 which can be a separator, is positioned between gas permeable cathode 110 and anode 160 and provides electrochemical cell 100 with an anodic compartment 165 separated from a cathodic compartment 135 by membrane 140.
  • a liquid anolyte 150 is provided to flow adjacent to anode 160 and between membrane 140 and anode 160, in anodic compartment 165.
  • Liquid catholyte 130 is provided to flow adjacent to gas permeable cathode 110 and between membrane 140 and gas permeable cathode 110, in cathodic compartment 135.
  • liquid anolyte 150 is provided to flow adjacent to anode 160 and between membrane 140 and anode 160, in anodic compartment 165.
  • liquid anolyte 150 flows along an inner surface of anode 160 as a liquid catholyte flow.
  • Membrane 140 separates liquid catholyte 130 and liquid anolyte 150 into distinct regions or compartments.
  • liquid catholyte 130 and liquid anolyte 150 provide the liquid electrolyte of the electrochemical cell 100.
  • Anode 160 is also preferably provided with an anodic catalyst that can be provided as part of anode 160 by convention means, for example by being deposited as an anodic catalyst layer on the surface of anode 160 facing anolyte 150 or by being provided as an integrated layer of anode 160.
  • the liquid anolyte flow rate is variable, and can be reversible in direction.
  • a flow direction of the liquid anolyte flow can be in the same direction as the liquid catholyte flow.
  • the liquid anolyte flow is in the opposite direction to the liquid catholyte flow.
  • Catholyte 130 containing mineral ions flows into electrochemical cell 100 as illustrated as a catholyte flow, preferably during operation catholyte 130 continuously flows into electrochemical cell 100.
  • Catholyte 130 flows along the surface (the inner surface, or a second surface) of gas permeable cathode 110 that faces catholyte 130 and that is preferably provided with cathodic catalyst layer 120.
  • Carbonate mineral i.e. produced or generated carbonate mineral, either in solution or as a precipitate, e.g. such as calcium carbonate if calcium ions are utilised
  • carbonate mineral with catholyte 130, continuously flows out of electrochemical flow cell 100 as exit flow 170 of catholyte 130 and carbonate mineral.
  • the carbonate mineral may not be a precipitate. That is, the carbonate mineral remains in solution in the catholyte.
  • Liquid anolyte 150 flows along the surface (the inner surface) of anode 160 that faces liquid anolyte 150 and that is preferably provided with an anodic catalyst layer. Liquid anolyte 150 flows out of anodic compartment 165 as at least part of an anodic compartment exit flow 175.
  • An electrical supply 190 is used to provide a desired voltage difference (i.e. voltage potential) between gas permeable cathode 110 and anode 160, or a desired current flow through gas permeable cathode 110.
  • Electrochemical cell 100 includes an anodic compartment 165 separated from a cathodic compartment 135 by membrane 140, preferably being an anion exchange membrane, a cation exchange membrane, an ion selective membrane or a bipolar membrane.
  • Input CO2 gas 105, or a mixture including CO2 gas is introduced into gas chamber 115 that faces the outer surface of gas permeable cathode 110, and output flow 180 of CO2 gas 105, or a mixture including CO2 gas, exits from gas chamber 115 or could be recirculated within gas chamber 115.
  • Anode 160 can be a gas permeable anode, e.g. a gas diffusion electrode, or can be a gas impermeable electrode, e.g. a solid metallic electrode.
  • Figure 2 illustrates an example of at least some electrochemical processes occurring at or in the vicinity of the gas-phase and liquid-phase interface of the electrochemical flow cell 100 illustrated in Figure 1.
  • Solid-liquid-gas interface 125 is the interface of the solid gas permeable cathode 110 / solid cathodic catalyst layer 120, liquid catholyte 130 and CO2 gas 105 having passed into gas permeable cathode 110.
  • Occurring at solid-liquid-gas interface 125 is an electrocatalytic reduction process that generates OH and reacts with Ca 2+ in the electrolyte.
  • Carbonate is formed from the CO2 gas being continuously supplied at least partially through gas permeable cathode 110 to chemically precipitate as solid carbonate mineral (CaC0 3 (s)) on the inner surface of gas permeable cathode 110 (the surface of gas permeable cathode 110 facing the liquid catholyte 130).
  • CO2 gas is transported or held in a gas chamber or a gas supply to be introduced to gas permeable cathode 110.
  • CO2 gas moves into and at least partially through gas permeable cathode 110 to interface 125 where it undergoes an electrochemical reaction.
  • Catholyte 130 is transported or held in a liquid catholyte chamber 135 or a liquid catholyte region to be introduced to gas permeable cathode 110 at interface 125.
  • Gas permeable cathode 110 is liquid impermeable so as to confine liquid catholyte 130 to the liquid catholyte chamber 130 or the liquid catholyte region.
  • the electrochemical cell may optionally be enclosed in a liquid-impermeable and gas-impermeable external housing (not illustrated).
  • the external housing may incorporate liquid conduit(s) that form inlet(s) and outlet(s) to allow for the ingress and egress of liquid electrolyte(s).
  • the liquid conduits may be connected to or in fluid communication with a liquid storage system(s), preferably an external liquid storage system that contains the liquid electrolyte(s). That is, optionally, at least one external liquid conduit is in fluid communication with an external liquid storage system for externally storing the liquid electrolyte(s).
  • the cathode and the anode are connected to an external electrical circuit, e.g.
  • the first electrical connection or the second electrical connection or the external electrical circuit itself may penetrate the external housing without compromising its gas- and liquid-impermeable nature.
  • the external electrical circuit can supply electrical energy to the cell.
  • FIG. 3 illustrates a configuration of another example electrochemical cell 300.
  • the electrochemical cell 300 is an electrochemical flow cell, meaning the electrolyte flows past an electrode in the electrochemical cell.
  • An input supply or flow of CO2 gas 305, or a mixture including CO2 gas, during operation continuously passes into a surface (the outer surface, or a first surface) of and at least partially through a gas permeable cathode 310, for example being a gas diffusion electrode (GDE) preferably provided with a cathodic catalyst, e.g. as a cathodic catalyst layer, or being a gas permeable membrane provided with a conducting layer including a cathodic catalyst.
  • GDE gas diffusion electrode
  • gas permeable cathode 310 faces the input supply of CO2 gas 305, or a mixture including CO2 gas.
  • Gas permeable cathode 310 is preferably liquid-impermeable so as to contain liquid electrolyte, i.e. liquid catholyte, although liquid electrolyte can penetrate gas permeable cathode 310 to a certain extent which may improve liquid-gas phase electrochemical interaction.
  • gas permeable membrane materials include polytetrafluoroethylene (PTFE), polyethylene (PE) and polypropylene (PP).
  • Gas permeable cathode 310 includes a cathodic catalyst layer 320, i.e. a catalyst layer or a first catalyst, that faces and contacts liquid electrolyte, i.e. liquid catholyte 330, at a solid-liquid-gas interface layer 325.
  • a cathodic catalyst layer 320 i.e. a catalyst layer or a first catalyst, that faces and contacts liquid electrolyte, i.e. liquid catholyte 330, at a solid-liquid-gas interface layer 325.
  • Cathodic catalyst layer 320 can be provided as part of gas permeable cathode 310 by conventional means, for example by being deposited on the surface of or joined to another layer, such as a non-conductive polymeric gas permeable membrane (if the catalyst is itself conductive or part of a conductive mixture) or a conductive support layer provided on the non-conductive polymeric gas permeable membrane, in which cases the cathodic catalyst layer 320 is provided as an integrated layer of overall gas permeable cathode 310.
  • Liquid catholyte 330 contains mineral ions, which in a particular example are calcium ions.
  • a membrane 340 which can be a separator, is positioned between gas permeable cathode 310 and gas permeable anode 360 and provides electrochemical cell 300 with an anodic compartment 365 separated from a cathodic compartment 335 by membrane 340.
  • a liquid anolyte 350 is provided to flow adjacent to gas permeable anode 360 and between membrane 340 and gas permeable anode 360, in anodic compartment 365.
  • Liquid catholyte 330 is provided to flow adjacent to gas permeable cathode 310 and between membrane 340 and gas permeable cathode 310, in cathodic compartment 335.
  • liquid anolyte 350 is provided to flow adjacent to gas permeable anode 360 and between membrane 340 and gas permeable anode 360, in anodic compartment 365.
  • liquid anolyte 350 flows along an inner surface of gas permeable anode 360 as a liquid catholyte flow.
  • Membrane 340 separates liquid catholyte 330 and liquid anolyte 350 into distinct regions or compartments.
  • liquid catholyte 330 and liquid anolyte 350 provide the liquid electrolyte of the electrochemical cell 300.
  • Gas permeable anode 360 is also preferably provided with an anodic catalyst that can be provided as part of gas permeable anode 360 by conventional means, for example by being deposited as an anodic catalyst layer on the surface of gas permeable anode 360 facing anolyte 350 or by being provided as an integrated layer of gas permeable anode 360.
  • the liquid anolyte flow rate is variable, and can be reversible in direction.
  • a flow direction of the liquid anolyte flow can be in the same direction as the liquid catholyte flow.
  • the liquid anolyte flow is in the opposite direction to the liquid catholyte flow.
  • Catholyte 330 containing mineral ions flows into electrochemical cell 300 as illustrated as a catholyte flow, preferably during operation catholyte 330 continuously flows into electrochemical cell 300.
  • Catholyte 330 flows along the surface (the inner surface, or a second surface) of gas permeable cathode 310 that faces catholyte 330 and that is preferably provided with cathodic catalyst layer 320.
  • Carbonate mineral i.e. produced or generated carbonate mineral, such as: sodium carbonate if sodium ions are utilised, potassium carbonate if potassium ions are utilised, or lithium carbonate if lithium ions are utilised
  • Liquid anolyte 350 flows along the surface (the inner surface) of gas permeable anode 360 that faces liquid anolyte 350 and that is preferably provided with an anodic catalyst layer. Liquid anolyte 350 flows out of anodic compartment 365 as at least part of an anodic compartment exit flow 375.
  • a flow of gas 385 such as hydrogen gas for example, can be directed to from cathode gas chamber 315 to an anode gas chamber so that flow of gas 385 is passed through the gas permeable anode 360 to react with the liquid anolyte.
  • An electrical supply 390 is used to provide a desired voltage difference (i.e. voltage potential) between gas permeable cathode 310 and gas permeable anode 360, or a desired current flow through gas permeable cathode 310 and/or gas permeable anode 360.
  • Electrochemical cell 300 includes an anodic compartment 365 separated from a cathodic compartment 335 by membrane 340, preferably being an anion exchange membrane, a cation exchange membrane, an ion selective membrane or a bipolar membrane.
  • Input CO2 gas 305, or a mixture including CO2 gas is introduced into cathode gas chamber 315 that faces the outer surface of gas permeable cathode 310, and output flow 380 of CO2 gas 305, or a mixture including CO2 gas, exits from cathode gas chamber 315 or could be recirculated within cathode gas chamber 315.
  • Gas permeable anode 360 can be a gas diffusion electrode.
  • FIG. 4 shows a flowchart of an example method 400 including the electrochemical induction of carbonate mineral from aqueous mineral ions (M) in the presence of CO2 gas continuously introduced into a gas permeable cathode, for example a gas diffusion electrode with a catalyst layer, or a non-conducting polymeric gas permeable membrane with an integrated conductive catalyst layer (i.e. a cathodic catalyst layer), or a non-conducting polymeric gas permeable membrane with a conductive layer and a cathodic catalyst layer.
  • the mineral ions (M) are or comprise: calcium ions, sodium ions, potassium ions, and/or lithium ions.
  • Method 400 includes the steps of:
  • the carbonate mineral may be in solution with the catholyte or a solid precipitate.
  • FIG. 5 shows a flowchart of another example method 500 including the electrochemical induction of calcium carbonate from aqueous calcium ions in the presence of CO2 gas continuously introduced into a gas permeable cathode, for example a gas diffusion electrode with a catalyst layer, or a non-conducting polymeric gas permeable membrane with an integrated conductive catalyst layer (i.e. a cathodic catalyst layer), or a non-conducting polymeric gas permeable membrane with a conductive layer and a cathodic catalyst layer.
  • Method 300 includes the steps of:
  • One side of the gas permeable cathode is in contact with the electrolyte containing a liquid-phase mineral, preferably calcium ions, sodium ions, potassium ions, and/or lithium ions.
  • the electrolyte containing a liquid-phase mineral can be any type of electrolyte that contains one or more minerals, such as for example calcium, sodium, potassium, lithium, magnesium, strontium and/or barium.
  • the electrolyte containing a liquid -phase mineral is preferably continuously flowing, i.e. there is a continuous flow of electrolyte past the gas permeable cathode, and fresh electrolyte or injection of electrolyte containing minerals, such as calcium chloride, can be introduced into an electrolyte chamber.
  • the electrolyte containing a liquid-phase mineral can include mineral ions, and/or other additive(s), preferably with one or more functionalities, such as:
  • gas permeable cathode 110, 310 allows introduction of CO2 gas, or a gas mixture including CO2 gas, preferably under continuous flow of gas, to the gas permeable membrane.
  • the CO2 gas is passed at least partially through the solid- phase gas permeable cathode 110, 310 which is in contact with the liquid-phase electrolyte (i.e. liquid-phase catholyte 130, 330).
  • the CO2 gas either remains as gas-phase CO2 or is converted to dissolved forms, such as carbonate and bicarbonate ions, within the electrolyte matrix containing one or more types of minerals.
  • the electrolyte includes mineral ions, for example calcium ions, sodium ions, potassium ions, and/or lithium ions, together with dissolved carbonate and/or bicarbonate derived from CO2 gas introduced via gas permeable cathode 110, 310, and then electrochemically reacts inducing hydroxide ions to form a carbonate mineral, for example calcium carbonate, sodium carbonate, potassium carbonate, and/or lithium carbonate.
  • mineral ions for example calcium ions, sodium ions, potassium ions, and/or lithium ions
  • an electrochemical mineral carbonation cell 100, 300 for capturing carbon dioxide 105, 305 the electrochemical cell 100, 300 comprising a gas permeable cathode 110, 310 wherein carbon dioxide gas 105, 305 is able to pass into an outer surface of and at least partially through the gas permeable cathode 110, 310 to react with a liquid catholyte 130, 330.
  • An anode 160, 360 is provided, wherein a voltage difference is able to be applied between the gas permeable cathode 110, 310 and the anode 160, 360.
  • a membrane 140, 340 is positioned between the gas permeable cathode 110, 310 and the anode 160, 360.
  • the liquid catholyte 130, 330 is positioned between the gas permeable cathode 110, 310 and the membrane 140, 340, the liquid catholyte including mineral ions.
  • a liquid anolyte 150, 350 is positioned between the anode 160, 360 and the membrane 140, 340.
  • the liquid catholyte 130, 330 flows along an inner surface of the gas permeable cathode 110, 310 and carbonate mineral is produced (for example upon reaction between electrochemically generated hydroxide and carbon dioxide) at, near or on the inner surface of the gas permeable cathode 110, 310 and is at least partially transported away from the inner surface of the gas permeable cathode 110, 310 by the liquid catholyte flow 130, 330.
  • Examples may include: sodium carbonate, potassium carbonate and/or lithium carbonate.
  • the mineral ions being used may be or may comprise sodium ions, potassium ions, and/or lithium ions.
  • Utilising sodium ions produces sodium carbonate.
  • Utilising potassium ions produces potassium carbonate.
  • Utilising lithium ions produces lithium carbonate.
  • the carbonate mineral may at least be partially removed and transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • Such carbonate mineral may include, for example, calcium carbonate.
  • the mineral ions being used may be or may comprise calcium ions. Utilising calcium ions produces calcium carbonate.
  • the carbon dioxide gas continuously passes at least partially through the gas permeable cathode 110, 310 and carbonate mineral is continuously produced at or near, or precipitated on, the inner surface of the gas permeable cathode 110, 310 and is continuously transported away from the inner surface of the gas permeable cathode 110,310 by continuous liquid catholyte flow 130, 330.
  • the gas permeable cathode 110, 310 is a gas diffusion electrode provided with a cathodic catalyst layer 120, 320.
  • the gas permeable cathode 110, 310 comprises a conductive cathodic catalyst layer, or the gas permeable cathode 110, 310 is a gas permeable membrane, preferably a non-conductive polymeric gas permeable membrane, provided with a conductive cathodic catalyst layer, or the gas permeable cathode 110, 310 is a gas permeable membrane, preferably a non- conductive polymeric gas permeable membrane, provided with a cathodic catalyst layer provided on a conductive layer that is deposited on, or positioned adjacent to, the gas permeable membrane.
  • the cathodic catalyst is provided as a cathodic catalyst layer 120, 320 at the inner surface of the gas permeable cathode 110, 310.
  • the cathodic catalyst layer is formed of or includes a hydrogen evolution catalyst.
  • the cathodic catalyst layer is formed of or includes an oxygen reduction catalyst.
  • the cathodic catalyst layer is formed of or includes a bi-functional catalyst or a multifunctional catalyst.
  • the cathodic catalyst layer is formed of or includes one or more metals selected from the group of noble metals (e.g. Pt, Ag), earth-abundant metals (e.g.
  • the cathodic catalyst layer is formed of or includes a hydrophobic material. In another example, the cathodic catalyst layer is formed of or includes a hydrophilic material.
  • the anode 160, 360 includes an anodic catalyst, preferably as an anodic catalyst layer.
  • the anodic catalyst layer is formed of or includes an oxygen evolution catalyst.
  • the anodic catalyst layer is formed of or includes a hydrogen oxidation catalyst.
  • the anodic catalyst layer is formed of or includes a chlorine evolution catalyst.
  • the gas permeable cathode 110, 310 includes a carbon protective layer.
  • a flow rate of the liquid catholyte flow is variable, preferably when the carbonate mineral is insoluble.
  • the liquid catholyte flow alternates between flowing in a first direction and flowing in a second direction past the inner surface of the gas permeable cathode.
  • the carbon dioxide gas 105, 305 is selected from the group of: pure carbon dioxide gas, substantially pure carbon dioxide gas, a gas mixture including carbon dioxide gas, ambient air, compressed air, industry waste gas including carbon dioxide, and a prepared gas mixture including carbon dioxide gas.
  • mineral containing liquid catholyte 130, 330 has an acidic to alkaline pH.
  • mineral containing liquid catholyte 130, 330 is at or about neutral pH.
  • the liquid catholyte (with for example 0.5 M NaCl and with DI water) may be, for example, about pH 5.0, about pH 5.5, about pH 6.0, about pH 6.5, about pH 7.0, about pH 7.5, about pH 8.0, about pH 8.5, or about pH 9.0, or from about pH 5.0 to about pH 9.0, or from about pH 5.0 to about pH 8.0, or from about pH 6.0 to about pH 8.0.
  • the liquid catholyte becomes more acidic, for example about pH 5.0.
  • the liquid anolyte 150, 350 is an electrolyte containing various concentration of proton and hydroxide ions, and the membrane 140, 340 is an ion exchange or ion selective membrane.
  • the liquid anolyte 150, 350 is an alkaline electrolyte and the membrane 140, 340 is an anion exchange, cation exchange or bipolar membrane.
  • the liquid anolyte 150, 350 is an acidic electrolyte and the membrane 140, 340 is a cation exchange, anion exchange or a bipolar membrane.
  • the liquid anolyte 150, 350 includes sodium chloride and has neutral pH and the membrane 140, 340 is a cation exchange, anion exchange, or a bipolar membrane.
  • the selection of type of membrane is dependent on both the catholyte and anolyte, and the ions preferred to be transferred.
  • an electrochemical system for capturing carbon dioxide that includes at least one electrochemical cell as described herein.
  • the electrochemical system includes a carbon dioxide gas source to supply the carbon dioxide gas 105, 305, and a power supply 190, 390 to apply the voltage difference between the gas permeable cathode 110, 310 and the anode 160, 360.
  • a liquid catholyte source supplies the liquid catholyte 130, 330, and an anolyte source supplies the liquid anolyte 150, 350.
  • a separation unit removes the carbonate mineral from the liquid catholyte flow.
  • a method of operating the electrochemical mineral carbonation cell 100, 300 to capture carbon dioxide and produce carbonate mineral including introducing carbon dioxide gas into the outer surface of the gas permeable cathode 110, 310 and allowing the carbon dioxide gas 105, 305 to pass at least partially through the gas permeable cathode 110, 310 to react with the liquid catholyte 130, 330 including mineral ions.
  • the liquid catholyte 130, 330 is positioned between an inner surface of the gas permeable cathode 110, 310 and the membrane 140, 340, and the membrane 140, 340 is positioned between the gas permeable cathode 110, 310 and the anode 160, 360.
  • the liquid anolyte 150, 350 is positioned between the anode 160, 360 and the membrane 140, 340.
  • the method also includes applying a voltage difference between the anode 160, 360 and the gas permeable cathode 110, 310, and flowing the liquid catholyte 130, 330 along the inner surface of the gas permeable cathode 110, 310.
  • carbonate mineral precipitate is formed (for example upon reaction between electrochemically generated hydroxide and carbon dioxide) on the inner surface of the gas permeable cathode 110, 310, and is at least partially removed and transported away from the inner surface of the gas permeable cathode 110, 310 by the flowing liquid catholyte 130, 330.
  • carbonate mineral is produced in solution at or near the inner surface of the gas permeable cathode 110, 310, and is at least partially transported away from the inner surface of the gas permeable cathode 110, 310 by the flowing liquid catholyte 130, 330.
  • the method further includes continuously circulating the liquid catholyte into and out of the electrochemical cell 100, 300. In another example, the method further includes continuously circulating the liquid anolyte into and out of the electrochemical cell 100, 300. In another example, the method further includes continuously introducing carbon dioxide gas into the outer surface of the gas permeable cathode 110, 310, and continuously removing and transporting away the carbonate mineral precipitate from the inner surface of the gas permeable cathode 110, 310 by the continuously flowing liquid catholyte 130, 330.
  • the method further includes continuously introducing carbon dioxide gas into the outer surface of the gas permeable cathode 110, 310, and continuously transporting away the carbonate mineral produced at or near the inner surface of the gas permeable cathode 110, 310 by the continuously flowing liquid catholyte 130, 330.
  • the method further includes a reductive catalytic process that generates localized alkalinity at the surface of the gas permeable cathode.
  • the method further includes that the carbonate mineral precipitate is removed from the flowing liquid catholyte and is collected.
  • the method further includes that the carbonate mineral in solution is removed from the flowing liquid catholyte and is collected.
  • the method further includes that a rate of carbonate mineral formation is changed by altering the applied voltage difference and/or by altering a current density through the gas permeable cathode.
  • the method operates at ambient air temperature and ambient air pressure.
  • hydroxide ions are formed by an electro-catalytic reaction, the hydroxide ions reacting with the mineral ions in the liquid catholyte and reacting with bicarbonate formed from the carbon dioxide gas.
  • the method includes regenerating the capture agent or sorbent, for example which are mineral ions being calcium ions, sodium ions, potassium ions or lithium ions, in the liquid catholyte.
  • Another example includes regenerating the mineral ions in the liquid catholyte by: (1) Reacting the carbonate mineral that has been collected with hydrochloric acid to form mineral chloride, CO2 and water. CO2 is stored as chemical feedstock with resale value.
  • the source of HC1 can be obtained fully or partially from anodic process within the electrochemical cell such as hydrogen oxidation, as following: H2(g) 2H + + 2e (aq).
  • Chloride from cathodic compartment is migrated through anion exchange membrane to the anodic compartment to form HC1: H + + Cl HC1.
  • Another process is chloride oxidation at the anode, where chlorine gas then react with water to form hydrochloric acid and hypochlorous acid, as following: Ck(g) + H2O (aq) HC1 (aq) + HOC1 (aq).
  • Hypochlorous acid is further transform to HC1 under light illumination, as following: 2HOC1 (aq) 2HC1 (aq) + 02(g).
  • hydrochloric acid can be an external outsourced chemical reagent or obtained from industry plants that emitted it as a waste.
  • the method includes regenerating the capture agent or sorbent, for example which is calcium ions in the liquid catholyte.
  • Another example includes regenerating the calcium ions in the liquid catholyte by: (1) Reacting the calcium carbonate that has been collected with hydrochloric acid to form calcium chloride, CO2 and water. CO2 is stored as chemical feedstock with resale value.
  • the source of HC1 can be obtained fully or partially from anodic process within the electrochemical cell such as chloride oxidation, as following: 2CT (aq) Cb (g) + 2e .
  • Chlorine gas then react with water to form hydrochloric acid and hypochlorous acid, as following: Ch(g) + H2O (aq) HC1 (aq) + HOC1 (aq).
  • Hypochlorous acid is further transform to HC1 under light illumination, as following: 2HOC1 (aq) 2HC1 (aq) + O2 (g).
  • 2HOC1 (aq) 2HC1 (aq) + O2 (g) when dilute HC1 is employed at the anode, an electrochemical reaction in the presence of 3 ⁇ 4 gas and chloride ions (supply across membrane from cathodic compartment) facilitates the formation of concentrated HC1.
  • chlorine gas at the anode can be reacted with the hydrogen generated at the cathode to form hydrochloric acid.
  • hydrochloric acid can be an external outsourced chemical reagent or obtained from industry plants that emitted it as a waste.
  • a first side (i.e. an outer side or an outer surface) of the solid gas permeable cathode allows continuous introduction of CO2 gas, or a gaseous mixture containing CO2 gas, as the gas is preferably under continuous flow.
  • the CO2 gas, or gas mixture is flown through the gas permeable cathode which on a second side (i.e. an inner side or an inner surface) is coated or impregnated with the catalyst (or one or more catalysts) and is in contact with liquid- phase electrolyte.
  • the electrolyte preferably contains mineral ions.
  • the CO2 gas or a gaseous mixture containing CO2 gas, either remains in gas phase or dissolves in forms such as carbonate and bicarbonate ions in the electrolyte matrix.
  • the reaction for example when using calcium ion being Ca 2+ + HCO3- + OH CaC0 3 + H2O, takes place in close proximity to, or adjacent to, or at, or near, or on, the gas permeable cathode and the produced carbonate mineral, for example when using calcium ions being deposited solid CaC0 3 , would otherwise cover the gas permeable cathode reducing its efficiency.
  • liquid electrolyte or at least the liquid catholyte
  • the gas permeable cathode to, in the case of a carbonate mineral that is produced as a precipitate such as calcium carbonate, transport away, remove, scrub or wash off the deposited solid carbonate mineral, for example CaCC .
  • liquid electrolyte or at least the liquid catholyte
  • the liquid electrolyte, or at least the liquid catholyte flows past or flows along, for example continuously flows past, or continuously flows along, the gas permeable cathode to, in the case of a carbonate mineral that is produced in solution, such as sodium carbonate, potassium carbonate or lithium carbonate, transport away, remove, flush or wash away the carbonate mineral in solution.
  • a carbonate mineral that is produced in solution such as sodium carbonate, potassium carbonate or lithium carbonate
  • the method of introducing CO2 gas via the gas permeable cathode is efficient and sensitive.
  • the conversion to calcium carbonate occurs under several examined conditions, including from using a 100 % high purity CO2 gas, to using a gas mixture including CO2 as low as 1 % by volume (mixed with inert gas such as Argon), to using atmospheric ambient air of 0.04 % CO2 by volume.
  • inert gas such as Argon
  • the presence of O2 is found to have a positive impact in increasing current densities due to an oxygen reduction reaction also contributing to hydroxide ion generation.
  • the formed carbonate mineral is continuously removed from the surface of the gas permeable cathode facing the continuous electrolyte flow, and the removed carbonate mineral is collected at a catholic reservoir. This is achieved by utilising one or more of the following factors:
  • the electrochemical cell design includes a selected spacing and volume of the cathodic electrolyte compartment, incorporating cathodic electrolyte inlets and outlets that improve the electrolyte flow and the collection of the carbonate mineral.
  • FIG. 6 is a schematic diagram showing electrochemically generated carbonate mineral 410 accumulating over time on or at an inner surface 125, 325 of gas permeable cathode 110, 310.
  • carbonate mineral 410 accumulates on the inner surface 125, 325 of gas permeable cathode 110, 310, resulting in a mass transfer issue, which lowers the process efficiency and reduces the quantity of produced carbonate mineral.
  • Figure 7 is a schematic diagram showing electrochemically generated carbonate mineral 510 being removed and transported away over time from an inner surface 125, 325 of gas permeable cathode 110, 310.
  • carbonate mineral 510 does not accumulate on or at the inner surface 125, 325 of gas permeable cathode 110, 310, which improves the process efficiency and increases the quantity of produced carbonate mineral.
  • the flow of electrolyte 520 provides an effective force to remove or wash away electrochemically generated carbonate mineral 510 from the inner surface 125, 325 of gas permeable cathode 110, 310 (contrasted to Figure 4).
  • the removed carbonate mineral 510 for example solid carbonate mineral, can be transported away and subsequently collected.
  • FIG. 8 is a schematic diagram showing electrochemically generated carbonate mineral 510 being removed from an inner surface 125, 325 of a gas permeable cathode 110, 310.
  • electrolyte 520 i.e. the electrolyte is flowing past the gas permeable cathode 110, 310
  • carbonate mineral 510 does not accumulate on or concentrate at the inner surface 125, 325 of gas permeable cathode 110, 310, which improves the process efficiency and increases the quantity of produced carbonate mineral.
  • the alternating flows of electrolyte 520 provides an effective force to remove or wash away electrochemically generated carbonate mineral 510 from the inner surface 125, 325 of gas permeable cathode 110, 310 (contrasted to Figure 4).
  • the alternating flows of electrolyte 520 alternates between flowing in a first direction and flowing in a second direction past the inner surface 125, 325 of gas permeable cathode 110, 310. Alternating the direction of flow of electrolyte 520, and/or flow rates, can enhance the mass transfer of carbonate mineral.
  • the removed carbonate mineral 510 for example solid carbonate mineral, can be transported away and subsequently collected.
  • the gas permeable cathode can be constructed or modified, preferably in any one or more the following ways: (1) Using a catalyst. For example, by applying a coating, preferably as a thin layer, of catalyst made of metallic, organic, inorganic or its hybrid materials, preferably by but not limited to air brushing, spray coating, electrodeposition, atomic layer deposition, chemical bathing or chemical vapour deposition.
  • a hydrophobic material for example PTFE
  • a hydrophilic material for example the Nafion ® membrane supplied by the Chemours company, which is a sulfonated tetrafluoroethylene based fluoropolymer- copolymer membrane
  • a mixture containing a hydrophobic material or a hydrophilic material during catalyst preparation that acts as a binder, and thereby improves the efficiency of channels for gas diffusion within the gas permeable cathode.
  • the collection of carbonate mineral in the catholyte reservoir includes a separation system, for example a filter system, to separate carbonate mineral from the liquid electrolyte (i.e. from the catholyte).
  • the separation system preferably uses a gravimetric process of carbonate mineral sedimentation (i.e. a gravimetric separation system), and/or uses a filter or filtering membrane.
  • Other separation systems that are known to the skilled person can be used for different types of carbonate minerals, for example if the carbonate mineral remains in solution.
  • the electrochemical cell 100, 300 includes an anodic compartment 165, 365 separated from a cathodic compartment 135, 335 by membrane 140, 340, preferably being an anion exchange membrane, a cation exchange membrane, an ion selective membrane or a bipolar membrane.
  • Anode 160, 360 can be a gas permeable anode, e.g. a gas diffusion electrode, or can be a gas impermeable electrode, e.g. a solid metallic electrode.
  • the gas permeable cathode has a catalyst layer, with the catalyst layer in contact with mineral containing electrolyte (initially neutral pH), coupled to the anode in an alkaline electrolyte separated by an anion exchange membrane.
  • the OH ions migrate to the gas permeable cathode and the pH of the unbuffered catholyte could change to become slightly alkaline.
  • the gas permeable cathode has a catalyst layer, with the catalyst layer in contact with mineral containing electrolyte at neutral pH, coupled to the anode in an acidic electrolyte separated by a cation exchange membrane.
  • pH of the catholyte remains neutral. If dilute HC1 is employed at the anode, an electrochemical reaction in the presence of 3 ⁇ 4 and chloride ions can facilitate the formation of concentrated HC1.
  • the gas permeable cathode has a catalyst layer, with the catalyst layer in contact with mineral containing electrolyte at neutral pH, coupled to the anode in an electrolyte containing sodium chloride at neutral pH separated by an ion-selective membrane.
  • chlorine gas is generated at the anode, as well as dissolved HC1 and HOC1.
  • the pH of the anolyte becomes acidic, and the pH of the catholyte remains near neutral.
  • Electrochemical cells in the stack can be connected in series or parallel depending on the preferable electrical configuration.
  • FIG. 9 illustrates an example configuration of a stack 700 of a plurality of electrochemical cells including multiple electrochemical cell units to produce carbonate mineral.
  • the configuration represents individually independent and separable electrochemical cells.
  • An electrochemical cell is repeated in the stack 700 and each electrochemical cell includes a gas permeable cathode 710, catholyte 730 that includes mineral ions and in which carbonate mineral is produced, membrane 740 separating catholyte 730 and anolyte 750.
  • Catholyte 730 is provided as a continuous flow and anolyte 750 is provided as a continuous flow.
  • Catholyte exit flow 770 contains the produced carbonate mineral, and preferably catholyte flow 770 is continuous during operation of the stack 700 of a plurality of electrochemical cells.
  • the multiple cathodes 710 of each cell can share a common electrical current collector.
  • FIG. 10 illustrates an example configuration of a stack 800 of a plurality of electrochemical cells including multiple electrochemical cell units to produce carbonate mineral.
  • the configuration represents an integrated stack configuration including each cathodic or anodic compartment sharing the same current collector.
  • An electrochemical cell includes a gas permeable cathode 810, where a cathode shares a current collector with patterned gas channels at both a front side and a back side, with each side in contact with the gas permeable cathode 810.
  • Anodes 860 share a current collector.
  • a voltage difference is applied across anodes 860, which are supplied with a relative positive electric potential, and cathodes 810, which are supplied with a relative negative electric potential.
  • Catholyte exit flow 870 contains the produced carbonate mineral, and preferably catholyte flow 870 is continuous during operation of the stack 800 of a plurality of electrochemical cells.
  • the cathode and anode are configurable with a shared cathodic current collector plate, and a shared anodic current collector plate, respectively.
  • the gas flow current collector at the cathode is patterned at both front and back sides, whereby both sides of the current collector are in contact with two gas permeable cathodes.
  • the flow of CO2 gas therefore shares the same common gas channel, hence having the same inlet gas flow and outlet gas flow for two electrochemical cells.
  • the anodes share the same current collector for two electrochemical cells.
  • FIG 11 illustrates an example configuration of a stack 900 of a plurality of electrochemical cells including multiple electrochemical cell units to produce carbonate mineral.
  • the configuration represents an integrated stack configuration including each cathodic or anodic compartment sharing the same current collector.
  • An electrochemical cell includes a gas permeable cathode 910, where a cathode shares a current collector with patterned gas channels at both a front side and a back side, with each side in contact with the gas permeable cathode 910.
  • An electrochemical cell also includes a gas permeable anode 960, where an anode shares a current collector with patterned gas channels at both a front side and a back side, with each side in contact with the gas permeable anode 960.
  • Catholyte exit flow 970 contains the produced carbonate mineral, and preferably catholyte flow 970 is continuous during operation of the stack 900 of a plurality of electrochemical cells.
  • the catholyte at the cathode for each individual cell is connected in parallel, having separate individual outlet channel facilitates for the collection of carbonate mineral, and for maintenance of a cell.
  • the anolyte flow is separated (connected in parallel channels) or is continuous (connected in series channels) for the stack of cells.
  • the regeneration process involves the recovery of mineral chloride (such as calcium chloride, sodium chloride, potassium chloride and/or lithium chloride for example) as a precursor electrolyte medium used to capture CO2 in the form of carbonate mineral (such as calcium carbonate, sodium carbonate, potassium carbonate and/or lithium carbonate for example).
  • mineral chloride such as calcium chloride, sodium chloride, potassium chloride and/or lithium chloride for example
  • carbonate mineral such as calcium carbonate, sodium carbonate, potassium carbonate and/or lithium carbonate for example
  • calcium carbonate, sodium carbonate, potassium carbonate, or lithium carbonate is reacted with hydrochloric acid to form calcium chloride, sodium carbonate, potassium carbonate or lithium carbonate respectively, as well as form CO2 and water.
  • the released CO2 is captured and stored, and potentially used as a chemical feedstock or a commodity product with resale value.
  • Mineral chloride and the associated electrolyte is reused for electrochemical CO2 capture.
  • concentrated hydrochloric acid is collected from an anodic reaction.
  • hydrochloric acid or chlorine gas is produced at the anode (within the same electrochemical cell) using a chloride oxidation reaction at the anode.
  • hydrogen at the cathode or external hydrogen is supplied to anode generates hydrochloric acid through hydrogen oxidation reaction.
  • Chloride ions can be transferred from cathodic to anodic compartment through an anion exchange membrane.
  • chloride oxidation occurs to generate chlorine, and chlorine is dissolved to form hydrochloric acid and hypochlorous acid. Hypochlorous acid is further reduced to hydrochloric acid by light illumination.
  • chlorine gas can be reacted with the hydrogen generated at the cathode to form hydrochloric acid.
  • chlorine gas can react directly with CaC0 3 to form CaC
  • calcium carbonate is heated to form calcium oxide, releasing CO2. Calcium oxide is then reacted with hydrochloric acid to form calcium chloride, CO2 and water.
  • Figure 12 illustrates an example electrochemical system 1000 including a stack 1010 of electrochemical cells, and associated example components to electrochemically capture CO2 in the form of carbonate mineral, optionally including regeneration of mineral ions.
  • the CO2 capture system 1000 comprises of a stack 1010 of a plurality of electrochemical cells, a power supply 1020 to supply a voltage differential to the cathodes/anodes of stack 1010, and containing tanks such as mineral tank 1030, chloride tank 1040, dilute hydrochloric acid tank (not shown).
  • a carbon dioxide gas source 1060 supplies carbon dioxide gas to a gas valve and/or gas flow meter 1070, where the carbon dioxide gas (or a gas mixture containing carbon dioxide gas) is supplied to stack of a plurality of electrochemical cells 1010.
  • a hydrogen gas source and/or a carbon feedstock source 1080 supplies hydrogen gas and/or carbon feedstock to the stack 1010 of a plurality of electrochemical cells.
  • Excess or unreacted carbon dioxide gas (or a gas mixture containing carbon dioxide gas) is reintroduced through gas line 1090 to be re input to stack 1010.
  • Pumps 1100 are used to draw material from tanks 1030, 1040 to supply materials, if desired, to stack 1010.
  • Separation unit 1110 (for example a filtration unit if the carbonate mineral is a solid precipitate) removes carbonate mineral from catholyte that can be held in carbonate mineral storage unit 1120.
  • regeneration unit 1050 uses hydrochloric acid and carbonate mineral from carbonate mineral storage unit 1120 for mineral ions regeneration supplied along pipe 1130 to mineral tank 1030. Any produced carbon dioxide can be stored in carbon dioxide tank 1140.
  • CO2 capture system 1000 thus provides two important aspects:
  • a system and method for carbon capture and storage that is CO2 stored as a carbonate mineral, such as calcium carbonate, sodium carbonate, potassium carbonate or lithium carbonate.
  • a system and method for regenerative carbon capture that is a carbonate mineral, such as calcium carbonate, sodium carbonate, potassium carbonate or lithium carbonate, can be regenerated to form mineral ions to again capture CO2.
  • a carbonate mineral such as calcium carbonate, sodium carbonate, potassium carbonate or lithium carbonate
  • the chemical reagent for mineral ion (e.g. calcium ion) regeneration e.g. HC1
  • HC1 a closed system of regeneration possible.
  • some CO2 emission plants generate HC1 which could be utilised for regeneration.
  • System 1000 includes carbon capture agent or sorbent source sub-system 1210, carbon capture sub system 1220, and regeneration sub-system 1230.
  • carbon dioxide gas is introduced into an outer surface of the gas permeable cathode, and the carbon dioxide gas is allowed to pass at least partially through the gas permeable cathode to react with a liquid catholyte including mineral ions.
  • the liquid catholyte is positioned between an inner surface of the gas permeable cathode and a membrane, the membrane positioned between the gas permeable cathode and an anode, and a liquid anolyte positioned between the anode and the membrane.
  • a voltage difference is applied between the anode and the gas permeable cathode.
  • the liquid catholyte flows along the inner surface of the gas permeable cathode.
  • the liquid anolyte flows along an inner surface of the anode.
  • Carbonate mineral is produced (for example upon reaction between electrochemically generated hydroxide and carbon dioxide).
  • Carbonate mineral may be a precipitate formed on the inner surface of the gas permeable cathode.
  • the carbonate mineral may be in an aqueous form. That is, the carbonate mineral is in solution in the catholyte, with the carbonate mineral soluble or partially soluble in the catholyte.
  • the carbonate mineral is at least partially transported away from the inner surface of the gas permeable cathode by the flowing liquid catholyte.
  • the mineral ions are regenerated in the liquid catholyte by reacting at least some of the removed carbonate mineral with hydrochloric acid or chlorine gas to form mineral chloride in solution in water.
  • the hydrochloric acid or the chlorine gas is produced at the anode.
  • the regeneration also includes storing released CO2 gas when forming the mineral chloride in solution in water.
  • an electrochemical system 1000 for capturing carbon dioxide comprising a stack 1010 of a plurality of electrochemical cells. At least one, or each, electrochemical mineral carbonation cell comprises a gas permeable cathode, an anode, a membrane positioned between the gas permeable cathode and the anode.
  • a carbon dioxide gas source 1060 introduces carbon dioxide gas into an outer surface of and at least partially through the gas permeable cathode.
  • a power supply 1020 applies a voltage difference between the gas permeable cathode and the anode.
  • a liquid catholyte source 1030 supplies a liquid catholyte as a liquid catholyte flow between the gas permeable cathode and the membrane, the liquid catholyte including mineral ions.
  • An anolyte source 1040 supplies a liquid anolyte between the anode and the membrane.
  • the liquid catholyte flows along an inner surface of the gas permeable cathode, and carbonate mineral is produced (for example upon reaction between electrochemically generated hydroxide and carbon dioxide) at or near, or on, the inner surface of the gas permeable cathode and is at least partially transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • the carbonate mineral may be precipitated on the inner surface of the gas permeable cathode and is at least partially removed and transported away from the inner surface of the gas permeable cathode by the liquid catholyte flow.
  • a separation unit 1110 removes the carbonate mineral from the liquid catholyte flow.
  • a liquid electrolyte pump 1100 forces the liquid catholyte flow between the gas permeable cathode and the membrane. In one example, the liquid electrolyte pump 1100 forces an alternating bi-directional flow of the liquid electrolyte. In one example, the liquid electrolyte pump 1100 provides a constant flow rate of the liquid electrolyte. In one example, the liquid electrolyte pump 1100 provides a variable flow rate of the liquid electrolyte.
  • FIG. 13 illustrates another example electrochemical system 1300.
  • the electrochemical system comprises an electrochemical cell 1310 containing any features as described with reference to any of the previously described embodiments of electrochemical cells, but additionally or alternatively may comprise other features that will be described with reference to Figure 13.
  • the electrochemical cell 1310 of Figure 13 can be configured to regenerate carbon dioxide after the electrochemical capture of carbon dioxide. This can be done through carbonation and/or acidification.
  • the regeneration of carbon dioxide through carbonation may be described as follows.
  • the electrochemical cell 1310 receives a gas stream 1315 containing carbon dioxide.
  • the carbon dioxide gas is captured by the electrochemical cell 1310 by reacting with the hydroxide ions contained in the catholyte 1320 (that is, the cation containing electrolyte) to generate carbonate mineral, thus resulting in the electrochemical capture of carbon dioxide.
  • the carbonate mineral produced from the electrochemical capture reaction of carbon dioxide gas in the cathodic compartment may be stored in a reservoir 1325 to be set aside for the regeneration of carbon dioxide gas.
  • it is pure carbon dioxide gas that is regenerated.
  • Carbon dioxide gas may be additionally or alternatively regenerated through acidification as follows. Hydrogen gas from the cathodic compartment or externally supplied can be passed into the anolyte 1330 for a hydrogen oxidation reaction that results in the concentrating of protons. For example, in producing hydrochloric acid, chloride can be transferred from the cathodic compartment through an anion exchange membrane. In the carbon dioxide regeneration process, the acid reservoir is then reacted with the carbonate and bicarbonate mineral to form carbon dioxide, water and mineral ions. Cation-based mineral ions can be reused for carbon dioxide capture process.
  • Hydrogen gas from the cathodic compartment or externally supplied can be passed into the anolyte 1330 for a hydrogen oxidation reaction that results in the concentrating of protons.
  • chloride can be transferred from the cathodic compartment through an anion exchange membrane.
  • the acid reservoir is then reacted with the carbonate and bicarbonate mineral to form carbon dioxide, water and mineral ions. Cation-based mineral ions can be reused for carbon
  • Figure 14 shows a representative SEM image of a sample of solid calcium carbonate produced and collected from an example electrochemical cell having a gas permeable cathode.
  • Figure 15 shows representative XRD and Raman spectroscopies confirming the formation of high purity calcium carbonate from the example electrochemical cell having a gas permeable cathode.
  • the sample of solid calcium carbonate was produced from an example electrochemical cell having a gas permeable cathode, constructed and operated as follows.
  • the gas permeable cathode was constructed of a gas diffusion electrode, (Sigracet 39 BCTM), deposited with 2 mg cm 2 10 wt % Pt on carbon black as a cathode catalyst containing Nafion dispersion as a binder.
  • Sigracet 39 BCTM is a non-woven carbon paper gas diffusion media with a Microporous Layer (MPL) that has been PTFE treated to 5%. It has a total thickness of 325 pm (microns).
  • the anode material is a nickel foam coated with a layer of nickel-iron layered double hydroxide catalyst prepared by hydrothermal method.
  • the gas permeable cathode and NiFe-LDH anode were assembled in a two-electrode full cell system as depicted in Figure 1.
  • the catholyte was 0.2 M CaCl 2 .2H 2 0 with 4 M NaCl as a supporting electrolyte, while the anolyte was 1 M KOH, supplied from two separate electrolyte reservoirs each with a volume of 15 ml. Both compartments were separated by an anion exchange membrane (Fumasep FAB-PK-130).
  • both catholyte and anolyte Prior to applying voltage, both catholyte and anolyte were circulated at a flow rate of 17.5 ml min 1 using a peristaltic pump (BT100-2J, Thermoline).
  • the CO2 gas (> 99.99 % purity) was introduced into the outer layer of the gas diffusion electrode at the cathodic chamber at a flow rate of 40 mL min 1 . All the experiments were performed at room temperature at ambient atmosphere. In one instance, the applied fixed voltage of 2.0 V resulted in current densities of ⁇ 70 mA cm 2 . In another instance, the applied fixed voltage of 3.0 V resulted in current densities of ⁇ 40 mA cm 2 . Within 10 min, the white calcium carbonate precipitation appears within the flow catholyte from the electrochemical cell to the catholyte reservoir, and the catholyte gradually became cloudy over the time due to accumulation of calcium carbonate.
  • the rate of calcium carbonate precipitation was significantly dependant on the applied current or voltage. For example, a current density of 100 mA cm 2 accelerates the calcium carbonate formation by completing carbonation in less than 20 min.
  • the operation voltages of each individual cell was varied, for example, between about 1.5 V to about 6 V.
  • the minimal current density of about 20 mA cm 2 was required to initiate sufficient amount of hydroxide ions, that reacts to form calcium carbonate.
  • the applied voltage and hence generated current densities also depends on the cell configuration with respect to geometry. For example, distance between gas permeable cathode and anode was about 1 cm for the above experiment. A shorter distance between cathode and anode will reduce the cell resistance, hence reducing the applied voltage.
  • Potential catalysts for the cathodic reaction are preferably, but not limited to, platinum, nickel, nickel phosphine, nickel chalcogenide, cobalt, cobalt phosphine, cobalt chalcogenide and metal alloys (such as PtNi).
  • platinum nickel, nickel phosphine, nickel chalcogenide, cobalt, cobalt phosphine, cobalt chalcogenide and metal alloys (such as PtNi).
  • hydrophobic polymeric membranes made of polytetrafluoroethylene and polyethylene can serve as a gas permeable membrane.
  • the catalyst can be deposited directly on the membrane or between a layer of conductor applied on the membrane.
  • Potential catalysts for the anodic reaction include, depending on the employed electrolytes: an alkaline solution (e.g. KOH), preferably but not limited to NiFe, Ni, Co, and metal alloys; an acidic solution (e.g. HC1), preferably but not limited to Pt, IrC , RuC ; or a neutral solution (e.g. NaCl) for chlorine generation, preferably but not limited to a range of dimensional stable electrodes containing mixed metal oxides such as Ti02:Ru02, or T1O2: IrC , or Ti02:Ru02:Ir02.
  • Soluble potassium and sodium carbonate were produced from an example electrochemical cell having a gas permeable cathode, constructed and operated as follows.
  • the gas permeable cathode comprised a gas diffusion electrode, (Sigracet 39 BCTM), deposited with 2 mg cm 2 10 wt % Pt on carbon black as a cathode catalyst containing Nafion dispersion as a binder.
  • the anode material is a nickel foam coated with a layer of nickel-iron layered double hydroxide catalyst prepared using a hydrothermal method.
  • the gas permeable cathode and NiFe-LDH anode were assembled in a two- electrode full cell system as depicted in Figure 1.
  • the catholyte was 4 M NaCl or KC1, while the anolyte was 1 M KOH, supplied from two separate electrolyte reservoirs each with a volume of 15 ml. Both compartments were separated by an anion exchange membrane (Fumasep FAB-PK-130) or a nafion membrane (NafionTM 117). Prior to applying voltage, both catholyte and anolyte were circulated at a flow rate of 17.5 ml min 1 using a peristaltic pump (BT100-2J, Thermo line).
  • the CO2 gas (> 99.99 % purity) or mixed CO2 with N2 gas or compressed air was introduced into the outer layer of the gas diffusion electrode at the cathodic chamber at a flow rate of 40 mL min 1 . All experiments were performed at room temperature at ambient atmosphere. The applied voltage between 1.5 V to 2.5 V resulting in current densities of 50 to 150 mA cm 2 . The carbonate formation was verified by titration with HC1 resulting in released of CO2. [0137] In another configuration, the Pt/C coated gas permeable electrode that served as a cathode as described above, was also used as an anode. The assembly of the two- electrode full cell was as shown in Figure 3.
  • the flowed catholyte was 4 M NaCl, and the flowed anolyte was 1M NaCl or diluted HC1 (e.g. 0.1 M).
  • the anolyte and catholyte was separated by an anion exchange membrane (Fumasep FAB -PK- 130) that promotes transfer of chloride ions and inhibits proton cross-over. Under an applied voltage, the hydrogen generated at the cathode or from an external source would be passed through the gas permeable anode to allow hydrogen oxidation process occurs at the cathode. This subsequently concentrating the acid.
  • a stream of CO2 containing gas (high purity CO2, mixed CO2 with N2 gas or compressed air) passed through the gas permeable cathode produced sodium carbonate.
  • CO2 containing gas high purity CO2, mixed CO2 with N2 gas or compressed air
  • sodium carbonate or sodium bicarbonate reacted with hydrochloric acid generated at anode, regeneration of carbon dioxide is achieved.
  • the lithium carbonate (soluble at room temperature) was produced from an example electrochemical cell having a gas permeable cathode, constructed and operated as follows.
  • the gas permeable cathode was constructed of a gas diffusion electrode, (Sigracet 39 BCTM), deposited with 2 mg cm 2 of 10 wt % Pt on carbon black as a cathode catalyst containing Nafion dispersion as a binder.
  • the anode material was a dimensionally stable (DSA) anode consists of IrC -TiC coated on titanium electrode.
  • DSA dimensionally stable
  • the flow through catholyte reservoir was comprised of 0.5 M L1CI2 and 0.5 M NaCl, and the flow through anolyte reservoir was 4 M NaCl.
  • a stream of CO2 containing gas such as high purity CO2 passed through the gas permeable cathode.
  • the applied fixed current e.g. 100 mA cm 2
  • lithium carbonate was produced.
  • Figure 16 shows example of Raman Spectra of the produced lithium carbonate in compared to that obtained from commercially available lithium carbonate sample.
  • a closed-loop CO2 capture system can be implemented using the as described electrochemical cell CO2 capture system for utilisation in CO2 gas emitted industrial processes, such as coal based power generation, cement production, steel production, and hydrogen production plants to capture emitted CO2 with a concentration range between about 10 % to about 30 % CO2 by volume.
  • the captured CO2 can be stored via the calcium regeneration strategy, and the calcium capture agent or sorbent can be reused for subsequent electrochemical CO2 mineral carbonation.
  • the as described electrochemical cell CO2 capture system is capable of handling a very low level of CO2, including utilising ambient air as an input gas feedstock.
  • the described CO2 capture system and method can act as a standalone, or component part, of direct air carbon capture technology.
  • the as described electrochemical cell CO2 capture system can be utilised to produce precipitated calcium carbonate for a wide range of applications, including for example as building and construction material, as a filler in paper, in plastics, in paints and coatings, and in personal heath and food production.
  • the as described electrochemical cell CO2 capture system and methods can be coupled to an existing cement production plant to directly capture CO2 for conversion to building materials.
  • calcium ions are extracted from the building and construction waste to recycle into calcium carbonate. High purity CO2 and calcium ions are applicable in this method to generate high purity calcium carbonate for use in applications that require high purity calcium carbonate.
  • Hard water is a common water problem found in the domestic and industry, particularly for countries/states with water supply of water hardness classified as hard water (e.g. dissolved hardness minerals of 7 to 10.5 grains per gallon) and very hard water (e.g. dissolved hardness minerals above 10.5 grains per gallon).
  • the most common hardness causing minerals are calcium and magnesium which are dissolved in a water supply.
  • the as described electrochemical cell CO2 capture system can be utilised to treat the water hardness by removing the dissolved minerals such as calcium and magnesium ions.
  • a CO2 source can be obtained from, for example, ambient air or a gas cylinder. This method offers a new strategy to the common approach of chemical treatment such as the use of water softeners, and a small quantity of sodium chloride may need to be added to improve the water electrical conductivity.
  • Oceans are the largest reservoir of carbon on earth. A large portion of anthropogenic CO2 dissolves in the seawater and is converted in equilibrium between hydrogen carbonate and carbonate ions.
  • the inventors have found that an in-situ CO2 storage process depends on the applied current density from CO2 electrolysis, in which higher current promotes the generation of hydroxide ions and hence calcification.
  • the electrochemical flow cell as previously described in figure 1 is utilised, with an exception that a three-electrode configuration was employed. In this configuration, the cathode is a working electrode, the anode is a counter electrode, and with an addition of a Ag/AgCl reference electrode located at the cathodic compartment.
  • the reported potential is converted to the Reversible Hydrogen Electrode (RHE).
  • RHE Reversible Hydrogen Electrode
  • GDE gas diffusion electrode
  • Example experiments employed the nano particulate Ag as a model catalyst.
  • Ag was deposited as a catalyst on the gas permeable layer (acting as the cathode) Sigracet 39 BCTM (Ag-GDL) by air brushing about 100 nm Ag dispersion containing Nafion ® (a membrane supplied by the Chemours company, which is a sulfonated tetrafluoroethylene based fluoropolymer-copolymer membrane, or also a proton-conductive polymer film), and was employed as a working cathode.
  • Nafion ® a membrane supplied by the Chemours company, which is a sulfonated tetrafluoroethylene based fluoropolymer-copolymer membrane, or also a proton-conductive polymer film

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Abstract

L'invention concerne une cellule électrochimique, un système et une méthode de capture de dioxyde de carbone. Dans un exemple, la cellule électrochimique de carbonatation minérale comprend une cathode perméable aux gaz et du dioxyde de carbone gazeux peut passer dans une surface extérieure et au moins partiellement à travers la cathode perméable aux gaz pour réagir avec un catholyte liquide. Une différence de tension peut être appliquée entre la cathode perméable aux gaz et une anode. Une membrane est positionnée entre la cathode perméable aux gaz et l'anode. Le catholyte liquide est positionné entre la cathode perméable aux gaz et la membrane et le catholyte liquide comprend des ions minéraux, par exemple des ions sodium, potassium, lithium ou calcium, un anolyte liquide est positionné entre l'anode et la membrane. Lors du fonctionnement de la cellule, le catholyte liquide s'écoule le long d'une surface interne de la cathode perméable aux gaz, et un minéral de carbonate, par exemple du carbonate de sodium, du carbonate de potassium, du carbonate de lithium ou du carbonate de calcium, est produit au niveau ou à proximité de la surface interne de la cathode perméable aux gaz et est au moins partiellement transporté à l'opposé de la surface interne de la cathode perméable aux gaz par le flux de catholyte liquide.
PCT/AU2022/050385 2021-04-28 2022-04-27 Capture électrochimique de dioxyde de carbone et production de minéral de carbonate WO2022226589A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5651875A (en) * 1992-03-13 1997-07-29 Eka Chemicals Oy Process for producing alkali metal hydroxide
US20180127886A1 (en) * 2016-11-04 2018-05-10 Korea Institute Of Energy Research Apparatus and method of preparing carbonate and/or formate from carbon dioxide
US20180195184A1 (en) * 2015-07-03 2018-07-12 Siemens Aktiengesellschaft Electrolytic System And Reduction Method For Electrochemical Carbon Dioxide Utilization, Alkali Carbonate Preparation And Alkali Hydrogen Carbonate Preparation
US20190256988A1 (en) * 2016-06-30 2019-08-22 Siemens Aktiengesellschaft System and Method for the Electrolysis of Carbon Dioxide

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5651875A (en) * 1992-03-13 1997-07-29 Eka Chemicals Oy Process for producing alkali metal hydroxide
US20180195184A1 (en) * 2015-07-03 2018-07-12 Siemens Aktiengesellschaft Electrolytic System And Reduction Method For Electrochemical Carbon Dioxide Utilization, Alkali Carbonate Preparation And Alkali Hydrogen Carbonate Preparation
US20190256988A1 (en) * 2016-06-30 2019-08-22 Siemens Aktiengesellschaft System and Method for the Electrolysis of Carbon Dioxide
US20180127886A1 (en) * 2016-11-04 2018-05-10 Korea Institute Of Energy Research Apparatus and method of preparing carbonate and/or formate from carbon dioxide

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