Systems and methods for tandem hydrogen production and carbon dioxide capture

Abstract

Disclosed herein are systems and methods for tandem hydrogen (H2) production and carbon dioxide (CO2) capture. For example, described herein are methods comprising tandem H2 production and CO2 capture and conversion to a carbonate mineral. In some examples, the method is an electrochemical method. In some examples, the method comprises dissolving CO2 in water and applying an electrochemical potential sufficient to drive the H2 evolution reaction, thereby producing H2 and CO3 2-. In some examples, the methods further comprise contacting the CO3 2- with a cation to thereby form an insoluble carbonate compound.

Description

[0001] SYSTEMS AND METHODS FOR TANDEM HYDROGEN PRODUCTION AND CARBON DIOXIDE CAPTURE

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 593,589, filed October 27, 2023, which is hereby incorporated herein by reference in its entirety.

[0004] BACKGROUND

[0005] The electrochemical H2 evolution reaction represents a potentially clean, renewable source of H2. However, this process requires the input of sufficient electrical energy to drive the demanding water splitting reaction. Systems and methods with improved properties, for example reducing the electrical energy required for H2 production from water, are needed. The methods and systems discussed herein addresses these and other needs.

[0006] SUMMARY

[0007] In accordance with the purposes of the disclosed methods and systems as embodied and broadly described herein, the disclosed subject matter relates to systems and methods for tandem hydrogen (H2) production and carbon dioxide (CO2) capture.

[0008] For example, described herein are methods comprising tandem H2 production and CO2 capture and conversion to a carbonate mineral. In some examples, the method is an electrochemical method. In some examples, the method comprises dissolving CO2 in water and applying an electrochemical potential sufficient to drive the H2 evolution reaction, thereby producing H2 and CCh2'. In some examples, the methods further comprise contacting the CCh2' with a cation to thereby form an insoluble carbonate compound.

[0009] In some examples, the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, or a combination thereof.

[0010] In some examples, the method further comprises dissolving a salt comprising the cation. In some examples, the salt is dissolved in the presence of the CCh2'. In some examples, after dissolving the salt, the cation is subsequently contacted with the CCh2'.

[0011] In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCl2, MnO, Mn(0H)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, CO3O4, CO(OH)2, C0CI2, NiO, Ni(0H)2, NiCh, CuO, Cu2O, Cu(OH)2, CuCh, ZnO, Zn(OH)2, ZnCb, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(0H)2, MgCh, FeCh, PbCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(0H)2, MgCh, or a combination thereof. In some examples, the salt comprises CaCh, MgCh, or a combination thereof. In some examples, the salt is provided by ocean water, brine, or a combination thereof.

[0012] In some examples, the energy required for H2 production from water is lowered by electrochemically coupling the reaction with the formation of the carbonate mineral.

[0013] Also disclosed herein are systems for performing any of the methods described herein.

[0014] Also disclosed herein are systems comprising an electrochemical cell comprising: a cathodic compartment comprising CO2 dissolved in water; a power source configured to apply a potential across the system sufficient to drive H2 evolution reaction, thereby producing H2 and COs2'; an anodic compartment; optionally a mixing compartment; wherein the anodic compartment and / or the mixing compartment comprise an aqueous solution comprising a cation capable of forming an insoluble carbonate compound; and a means for transporting the COs2' anions and / or the cations, such that the COs2' anions contact the cations to thereby form an insoluble carbonate compound.

[0015] In some examples, the CO2 is pre-dissolved in the water. In some examples, the CO2 is directly purged or bubbled in the water within the cathodic compartment.

[0016] In some examples, the means for transporting the COs2' anions comprises physical mixing, an ion exchange membrane (e.g., a cation exchange membrane), a bipolar membrane, or a combination thereof.

[0017] In some examples, the system comprises the mixing compartment, wherein the COs2' anions contact the cations within the mixing compartment to thereby form the insoluble carbonate compound.

[0018] In some examples, the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, or a combination thereof.

[0019] In some examples, the cation is provided by dissolving a salt comprising the cation. In some examples, the salt comprises CaO, Ca(0H)2, CaCh, MgO, Mg(0H)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCh, MnO, Mn(OH)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, CO3O4, CO(OH)2, C0CI2, NiO, Ni(OH)2, NiCh, CuO, Cu2O, Cu(OH)2, CuCh, ZnO, Zn(0H)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, FeCh, PbCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(0H)2, MgCh, or a combination thereof. In some examples, the salt comprises CaCh, MgCh, or a combination thereof. In some examples, the salt is provided by ocean water, brine, or a combination thereof.

[0020] In some examples, the system is configured to perform any of the methods described herein.

[0021] In some examples, the system comprises that shown schematically in Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, or a combination thereof.

[0022] In some examples, the system further comprises a cation exchange membrane, an anion exchange membrane, a gas diffusion electrode, or a combination thereof.

[0023] Also disclosed herein are methods of use of any of the systems described herein. For example, using the system to perform any of the methods described herein.

[0024] Additional advantages of the disclosed systems and methods will be set forth in part in the description which follows, and in part will be obvious from the description. The advantages of the disclosed systems and methods will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed devices and methods, as claimed.

[0025] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

[0026] BRIEF DESCRIPTION OF THE FIGURES

[0027] The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure, and together with the description, serve to explain the principles of the disclosure.

[0028] Figure 1. A schematic diagram of an example reactor design which has no membrane, only physical mixing.

[0029] Figure 2. A schematic diagram of an example reactor design which includes a single membrane (no bipolar membrane).

[0030] Figure 3. A schematic diagram of an example reactor design that is similar to that of Figure 2, but with mixing directly in the cathode compartment.

[0031] Figure 4. A schematic diagram of an example reactor design that includes bipolar membranes. Figure 5. A schematic diagram of an example reactor design using CaCE and / or MgCE, potentially from ocean water and / or brine, as the Ca2+ / Mg2+source.

[0032] Figure 6. XRD of CaCCh produced from precipitation with CaCE.

[0033] Figure 7. XRD of MgCCh produced from precipitation with MgCE.

[0034] Figure 8. XRD of FeCCh produced from precipitation with FeCE.

[0035] Figure 9. XRD of PbCCh produced from precipitation with PbCE.

[0036] Figure 10. XRD of CaCCh produced from precipitation with Ca(OH)2.

[0037] Figure 11 shows the energy required for EE production in Electrolyte A with N2 only (Baseline value), with CO2 (Method 1), and with CO2 and Ca(OH)2 (Method 2).

[0038] Figure 12 shows the energy required for EE production in Electrolyte B with N2 only (Baseline value), with CO2 (Method 1), and with CO2 and Ca(OH)2 (Method 2).

[0039] Figure 13 shows the energy savings provided by this technology calculated as the reduction in energy per kg of EE produced by Methods 1 and 2 as measured in both Electrolytes A and B.

[0040] Figure 14 shows the energy savings provided by this technology calculated as the reduction in energy per kg of CO2 captured by Capture Methods 1 and 2 as measured in both Electrolytes A and B.

[0041] DETAILED DESCRIPTION

[0042] The systems and methods described herein may be understood more readily by reference to the following detailed description of specific aspects of the disclosed subject matter and the Examples included therein.

[0043] Before the present systems and methods are disclosed and described, it is to be understood that the aspects described below are not limited to specific synthetic methods or specific reagents, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0044] Also, throughout this specification, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which the disclosed matter pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.

[0045] In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings. Throughout the description and claims of this specification the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps.

[0046] As used in the description and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a composition” includes mixtures of two or more such compositions, reference to “an agent” includes mixtures of two or more such agents, reference to “the component” includes mixtures of two or more such components, and the like.

[0047] “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0048] Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. By “about” is meant within 5% of the value, e.g., within 4, 3, 2, or 1% of the value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0049] Values can be expressed herein as an “average” value. “Average” generally refers to the statistical mean value.

[0050] By “substantially” is meant within 5%, e.g., within 4%, 3%, 2%, or 1%.

[0051] “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0052] It is understood that throughout this specification the identifiers “first” and “second” are used solely to aid in distinguishing the various components and steps of the disclosed subject matter. The identifiers “first” and “second” are not intended to imply any particular order, amount, preference, or importance to the components or steps modified by these terms.

[0053] References in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound. A weight percent (wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

[0054] The term “or combinations thereof’ as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof’ is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CAB ABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

[0055] Systems and Methods

[0056] Disclosed herein are systems and methods for tandem hydrogen (H2) production and carbon dioxide (CO2) capture.

[0057] For example, disclosed herein are methods comprising tandem H2 production and CO2 capture and conversion to a carbonate mineral.

[0058] In some examples, the method is an electrochemical method.

[0059] In some examples, the method comprises dissolving CO2 in water and applying an electrochemical potential sufficient to drive the H2 evolution reaction, thereby producing H2 and CO32’. In some examples, the methods further comprise contacting the CO32' with a cation to thereby form an insoluble carbonate compound.

[0060] In some examples, the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, or a combination thereof.

[0061] In some examples, the methods further comprise dissolving a salt comprising the cation. In some examples, the salt is dissolved in the presence of the CO32'. In some examples, after dissolving the salt, the cation is subsequently contacted with the CO32'.

[0062] In some examples, the salt comprises CaO, Ca(0H)2, CaCh, MgO, Mg(0H)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCl2, MnO, Mn(OH)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, Co3O4, Co(OH)2, C0CI2, NiO, Ni(OH)2, NiCh, CuO, Cu2O, Cu(OH)2, CuCh, ZnO, Zn(0H)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(0H)2, CaCh, MgO, Mg(0H)2, MgCh, FeCh, PbCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(0H)2, CaCh, MgO, Mg(0H)2, MgCh, or a combination thereof. In some examples, the salt comprises CaCh, MgCh, or a combination thereof. In some examples, the nitrate or sulfates salts are used with or in place of the corresponding chloride salts. In some examples, the cation can be formed by oxidizing the corresponding metallic species at the anode.

[0063] In some examples, the salt is provided by ocean water, brine, or a combination thereof. For example, the methods can further comprise water purification, such as water desalination.

[0064] In some examples, the CO2 is provided by ambient air, a flue gas, or a combination thereof.

[0065] In some examples, the energy required for H2 production from water in the methods described herein is lowered by electrochemically coupling the reaction with the formation of the carbonate mineral.

[0066] Also described herein are systems for performing any of the methods described herein.

[0067] Also disclosed herein are systems comprising an electrochemical cell comprising: a cathodic compartment comprising CO2 dissolved in water. The systems can further comprise a power source configured to apply a potential across the system sufficient to drive H2 evolution reaction, thereby producing H2 and CCh2'. The systems further comprise an anodic compartment and optionally a mixing compartment, wherein the anodic compartment and / or the mixing compartment comprise an aqueous solution comprising a cation capable of forming an insoluble carbonate compound. The systems further comprise a means for transporting the CCh2' anions and / or the cations, such that the CCh2' anions contact the cations to thereby form an insoluble carbonate compound.

[0068] In some examples, the CO2 is pre-dissolved in the water. In some examples, the CO2 is directly purged or bubbled in the water within the cathodic compartment.

[0069] In some examples, the CO2 is provided by ambient air, a flue gas, or a combination thereof.

[0070] In some examples, the means for transporting the CCh2' anions comprises physical mixing, an ion exchange membrane (e.g., a cation exchange membrane), a bipolar membrane, or a combination thereof.

[0071] In some examples, the system further comprises the mixing compartment, wherein the CO32’ anions contact the cations within the mixing compartment to thereby form the insoluble carbonate compound.

[0072] In some examples, the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof. In some examples, the cation comprises Ca2+, Mg2+, or a combination thereof.

[0073] In some examples, the cation is provided by dissolving a salt comprising the cation. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(0H)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCh, MnO, Mn(OH)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCl2, CoO, CO3O4, CO(OH)2, C0CI2, NiO, Ni(OH)2, NiCh, CuO, Cu2O, Cu(OH)2, CuCh, ZnO, Zn(0H)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(0H)2, MgCh, FeCh, PbCh, or a combination thereof. In some examples, the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(0H)2, MgCh, or a combination thereof. In some examples, the salt comprises CaCh, MgCh, or a combination thereof. In some examples, the nitrate or sulfates salts are used with or in place of the corresponding chloride salts. In some examples, the cation can be formed by oxidizing the corresponding metallic species at the anode. In some examples, the salt is provided by ocean water, brine, or a combination thereof.

[0074] In some examples, the system comprises the system shown schematically in Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, or a combination thereof.

[0075] In some examples, the system utilizes a cation exchange membrane, an anion exchange membrane, a gas diffusion electrode, or a combination thereof.

[0076] Also disclosed herein are methods of use of any of the systems described herein. For example, the method can comprise using the system to perform any of the methods described herein.

[0077] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

[0078] The examples below are intended to further illustrate certain aspects of the devices and methods described herein, and are not intended to limit the scope of the claims.

[0079] EXAMPLES

[0080] The following examples are set forth below to illustrate the methods and results according to the disclosed subject matter. These examples are not intended to be inclusive of all aspects of the subject matter disclosed herein, but rather to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the present invention which are apparent to one skilled in the art. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric. There are numerous variations and combinations of measurement conditions, e.g., component concentrations, temperatures, pressures and other measurement ranges and conditions that can be used to optimize the described process.

[0081] Example 1 - Tandem H2 Production and CO2 Capture / Conversion to Carbonate Mineral

[0082] The electrochemical H2 evolution reaction represents a potentially clean, renewable source of H2. However, this process requires the input of sufficient electrical energy to drive the demanding water splitting reaction. It has been demonstrated that H2 production from the reduction of H2CO3 and HCCU to CCh2' proceeds at lower overpotentials and at a faster rate compared to H2 production from water.

[0083] H2CO3 and HCCU is produced spontaneously by dissolving gaseous CO2 in water. As H2CO3 and HCCU is converted to CCh2' via electrochemical H2 production, the solution becomes basic. This further favors the dissolution of CO2 resulting in additional CCh2' formation. As the concentration of CCh2' increases, the H2 evolution reaction becomes hindered due to increase in solution pH and the depletion of H2CO3 and HCCU. However, during this process CO2 has been converted to CCh2' and captured in the solution. This can be described by the following two reactions:

[0084] CO2 + H2O H2CO3 (1)

[0085] H2CO3 + 2e H2+ CO32’ (2)

[0086] Addition of aqueous Ca2+would result in the precipitation of CaCCh due to its very low solubility. Aqueous CaCh is one potential source of Ca2+, which could be obtained from ocean water or brine. This would decrease the solution pH and allow the continued formation of H2CO3 and HCCU from gaseous CO2 enabling the continuous, efficient production of H2. Importantly, the biproduct of this reaction is the conversion of gaseous CO2 to CaCCh. CaCCh is a stable mineral resulting in the permanent removal of CO2 from the atmosphere. CaCCh is also known as limestone and has commercial value as a primary ingredient in cement and other building materials. This process is shown in the following reaction:

[0087] CaCh + CO32’ CaCOsw + 2C1’ (3) The above three equations describe the chemistry proceeding in the cathodic half-cell. In the corresponding anodic half-cell of the electrochemical system, the following reaction proceeds:

[0088] H2O ¥2 O2 + 2H++ 2e (4)

[0089] The resulting net reaction can be written as:

[0090] CO2 + CaCh + 2H2O H2+ 72O2 + CaCO3w + 2HC1 (5 - Net Reaction)

[0091] The overall result of this process is thus the tandem production of H2 from water and the capture and conversion of gaseous CO2 to mineral CaCCh. Both of these tandem processes have significant commercial potential, especially considering that the energy requirement for this net reaction is even less than for traditional water splitting. This means that the production of H2 can occur at a potential that is even lower than the traditionally accepted thermodynamic limit for water splitting. This occurs by driving the reaction forward by the tandem capture and mineralization of CO2, or in other words CO2 capture at a negative energy cost during efficient, sustainable H2 production.

[0092] Note that this process is not specific to Ca2+. An analogous process could occur using Mg2+or other cations that form insoluble salts with CCh2' in place of or in addition to Ca2+. The process is also not specific to CT. A similar process could occur using other sources of Ca2+or Mg2+in place of or in addition to CaCh or MgCh.

[0093] Example 2 - Tandem H2 Production and CO2 Capture / Conversion to Carbonate Mineral

[0094] Cathodic reaction:

[0095] Anodic reaction:

[0096] Net reaction:

[0097] Alternative net: Replacing CaCh with Ca(0H)2: (or CaCO3+ H2O)

[0098] Equivalent to above since:

[0099] In summary:

[0100] CO2 + salt water - H2 + limestone

[0101] Could combine H2 and O2 to purify water, i.e., water desalination and CO2 capture.

[0102] Advantages over existing technologies:

[0103] Combines CO2 capture with H2 production, producing 1 mol H2 per mole of CO2 captured;

[0104] - Uses electrochemical current to sustain the pH gradient needed for CO2 capture (CO2 typically acidifies the solution, which must be kept basic for continued capture);

[0105] - Energy input to maintain pH gradient is not lost - it is recovered as H2.

[0106] Example 3

[0107] This technology can be simply described as reducing the electrical energy required for H2 production from water by electrochemically coupling this reaction with the formation of carbonate mineral (e.g., CaCO3, MgCO3). When CO2 serves as the C source for this process, the result of these coupled reactions is tandem production of H2 and mineralization of CO2.

[0108] Various methods can exist for electrochemically coupling these reactions. Many of these will share the following common features:

[0109] 1. Presence of dissolved CO2 / H2CO3 / HCO37CO32' in the cathodic compartment where the H2 evolution half reaction occurs. This can be accomplished by direct CO2 purging into the cathodic compartment or by pre-saturation of the electrolyte with CO2.

[0110] 2. Using the H2 evolution half-reaction to shift the equilibrium of these carbonate species toward the fully deprotonated CO32' anion.

[0111] 3. Subsequent removal of CO32' by precipitation with a counter cation. Candidate cations for precipitation are Ca2+and / or Mg2+, but there may be others.

[0112] Examples exist of separately implementing one or two of the above conditions; however, the combination of these three conditions are sufficient to define a new technology.

[0113] The benefits of electrochemical H2 evolution using this method that are not realized in traditional electrochemical cells for water splitting include: 1. Reducing the thermodynamics potential required for H2 production from water by electrochemically coupling this reaction with the formation of carbonate mineral (e.g., CaCCh, MgCCh). Note that this is a thermodynamic advantage.

[0114] 2. Reducing the overpotential required for H2 evolution. This is realized because reduction of H2CO3 and HCCh' is kinetically favored over reduction of H2O, especially at low overpotentials. Note that this is a kinetic advantage.

[0115] 3. Tandem capture and mineralization of CO2 during H2 production. Note that in this process CO2 capture does not require excess energy; rather it contributes energetically to the H2 evolution reaction. Therefore, this process represents CO2 capture and mineralization at a negative energy cost.

[0116] The cation utilized to precipitate CCh2' is a consumable of the reaction. Multiple cations may be used for this process. A requirement is that the cation must form a solid precipitate with CO32’. Cations can be utilized either as solids (e.g., oxides or hydroxides) or as aqueous solutions. For example, Ca2+can be obtained from solid CaO and / or Ca(0H)2. Similarly, Mg2+can be obtained from solid MgO and / or Mg(0H)2. Alternatively, Ca2+and / or Mg2+may be obtained from ocean water as CaCh and MgCh, respectively. Straightforward variations of this process are easily envisioned depending on the source and form of Ca2+, Mg2+, or other cation.

[0117] Examples of Reactor Designs. Specific examples of various reactor schemes for reducing this technology to practice are shown in Figure 1 - Figure 5. Some of these designs include the use of ion exchange membranes (e.g., a cation exchange membrane, CEM) and / or bipolar membranes (BPM, bipolar membrane), while others do not. Each of these share the three common features described above.

[0118] The reactor design in Figure 1 has no membrane, only physical mixing.

[0119] The reactor design in Figure 2 includes a single membrane (no bipolar membrane).

[0120] The reactor design in Figure 3 is similar to that of Figure 2, but with mixing directly in the cathode compartment.

[0121] The reactor design in Figure 4 includes bipolar membranes.

[0122] The reactor design in Figure 5 is an example of using CaCh and / or MgCh, potentially from ocean water and / or brine, as the Ca2+ / Mg2+source.

[0123] Ho et al. describes the circular indirect carbonation of coal fly ash for carbon dioxide capture and utilization (Ho et al. Journal of Environmental Chemical Engineering, 2022, 10 108269). However, the reactor scheme described by Ho et al. does not include the presence of dissolved CO2 / H2CO3 / HCO37CO32' in the cathodic compartment. Consequently, the implementation of Ho et al. does not benefit from a reduction in electrical energy required for H2 production since the H2 evolution and CO2 mineralization reactions are not electrochemically coupled in Ho et al. as described herein.

[0124] Example 4 - Tandem H2 Evolution and CO2 Capture

[0125] Hydrogen (H2) was produced by electrolysis using platinum electrodes in two different electrolytes, designated below as Electrolyte A and Electrolyte B. In both cases, the energy consumed by H2 production was measured with only nitrogen (N2) and electrolyte present in the anode and cathode cells. This measurement in N2 represents a baseline energy consumption required for H2 production without the benefit of the present invention.

[0126] Following baseline measurement, carbon dioxide (CO2) was introduced to the system and began to be captured. Two capture methods were demonstrated, and results were compared. In the first capture method, CO2 was captured by the electrolyte as carbonate (CO32). CCh2' can then be mineralized by precipitation with any metal cation forming an insoluble carbonate salt. Examples of calcium carbonate (CaCCh), magnesium carbonate (MgCCh), iron carbonate (FeCCh), and lead carbonate (PbCCh) formed by precipitation with calcium chloride (CaCh), magnesium chloride (MgCh), iron chloride (FeCh), and lead chloride (PbCh), respectively, were specifically demonstrated, and X-ray diffraction patterns of the resulting minerals are shown in Figure 6 - Figure 9.

[0127] In the second capture method, calcium hydroxide (Ca(0H)2) was added to the system, which dissolved in the anode cell to produce Ca2+. The Ca2+thus produced was then used to precipitate CCh2' as calcium carbonate (CaCCh) by mixing the anode and cathode solutions. The X-ray diffraction pattern of the resulting CaCCh mineral is provided as Figure 10.

[0128] Figure 11 shows the energy required for H2 production in Electrolyte A with N2 only (Baseline value), with CO2 (Method 1), and with CO2 and Ca(OH)2 (Method 2). Figure 12 shows the same results for Electrolyte B. Dark grey bars show the best (i.e., lowest) energy consumption observed for H2 production during the CO2 capture process, while the sum of dark grey and light grey bars show the average energy consumption observed during the entire capture process.

[0129] Figure 13 shows the energy savings provided by this technology calculated as the reduction in energy per kg of H2 produced by Methods 1 and 2 as measured in both Electrolytes A and B. Dark grey bars show the average energy reduction observed during the CO2 capture process, while the sum of dark grey and light grey bars show the highest energy reduction observed during the entire capture process. Figure 14 shows the energy savings provided by this technology calculated as the reduction in energy per kg of CO2 captured by Capture Methods 1 and 2 as measured in both Electrolytes A and B. To quantify the amount of CO2 captured, a stoichiometry of one CO2 molecule captured per H2 molecule produced was assumed as given by the net electrochemical reaction (see Equation 5 above). Dark grey bars show the average energy reduction observed during the CO2 capture process, while the sum of dark grey and light grey bars show the best (i.e., highest) energy reduction observed during the capture process.

[0130] EXEMPLARY ASPECTS

[0131] In view of the described compositions, devices, systems, and methods, herein below are described certain more particularly described aspects of the inventions. The particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0132] Example 1 : A method comprising tandem H2 production and CO2 capture and conversion to a carbonate mineral.

[0133] Example 2: The method of any examples herein, particularly example 1, wherein the method is an electrochemical method.

[0134] Example 3 : The method of any examples herein, particularly example 1 or example 2, wherein the method comprises: dissolving CO2 in water and applying an electrochemical potential sufficient to drive the H2 evolution reaction, thereby producing H2 and CCh2'; and contacting the CCh2' with a cation to thereby form an insoluble carbonate compound.

[0135] Example 4: The method of any examples herein, particularly example 3, wherein the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof.

[0136] Example 5: The method of any examples herein, particularly example 3 or example 4, wherein the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof.

[0137] Example 6: The method of any examples herein, particularly examples 3-5, wherein the cation comprises Ca2+, Mg2+, or a combination thereof.

[0138] Example 7: The method of any examples herein, particularly examples 3-6, wherein the method further comprises dissolving a salt comprising the cation.

[0139] Example 8: The method of any examples herein, particularly example 7, wherein the salt is dissolved in the presence of the CCh2'. Example 9: The method of any examples herein, particularly example 7, wherein, after dissolving the salt, the cation is subsequently contacted with the CCh2'.

[0140] Example 10: The method of any examples herein, particularly examples 7-9, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCh, MnO, Mn(0H)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, Co3O4, Co(OH)2, C0CI2, NiO, Ni(OH)2, NiCh, CuO, Cu2O, Cu(OH)2, CuCh, ZnO, Zn(OH)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCh, or a combination thereof.

[0141] Example 11 : The method of any examples herein, particularly examples 7-10, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, FeCh, PbCh, or a combination thereof.

[0142] Example 12: The method of any examples herein, particularly examples 7-11, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, or a combination thereof.

[0143] Example 13: The method of any examples herein, particularly examples 7-12, wherein the salt comprises CaCh, MgCh, or a combination thereof.

[0144] Example 14: The method of any examples herein, particularly examples 7-13, wherein the salt is provided by ocean water, brine, or a combination thereof.

[0145] Example 15: The method of any examples herein, particularly examples 1-14, wherein the energy required for Eh production from water is lowered by electrochemically coupling the reaction with the formation of the carbonate mineral.

[0146] Example 16: A system for performing the methods of any examples herein, particularly examples 1-15.

[0147] Example 17: A system comprising an electrochemical cell comprising: a cathodic compartment comprising CO2 dissolved in water; a power source configured to apply a potential across the system sufficient to drive Eh evolution reaction, thereby producing Eh and CCh2'; an anodic compartment; optionally a mixing compartment; wherein the anodic compartment and / or the mixing compartment comprise an aqueous solution comprising a cation capable of forming an insoluble carbonate compound; and a means for transporting the CCh2' anions and / or the cations, such that the CCh2' anions contact the cations to thereby form an insoluble carbonate compound.

[0148] Example 18: The system of any examples herein, particularly example 17, wherein the CO2 is pre-dissolved in the water.

[0149] Example 19: The system of any examples herein, particularly example 17 or example 18, wherein the CO2 is directly purged or bubbled in the water within the cathodic compartment. Example 20: The system of any examples herein, particularly examples 17-19, wherein the means for transporting the CCh2' anions comprises physical mixing, an ion exchange membrane (e.g., a cation exchange membrane), a bipolar membrane, or a combination thereof.

[0150] Example 21 : The system of any examples herein, particularly examples 17-20, further comprising the mixing compartment, wherein the CCh2' anions contact the cations within the mixing compartment to thereby form the insoluble carbonate compound.

[0151] Example 22: The system of any examples herein, particularly examples 17-21, wherein the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof.

[0152] Example 23: The system of any examples herein, particularly examples 17-22, wherein the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof.

[0153] Example 24: The system of any examples herein, particularly examples 17-23, wherein the cation comprises Ca2+, Mg2+, or a combination thereof.

[0154] Example 25: The system of any examples herein, particularly examples 17-24, wherein the cation is provided by dissolving a salt comprising the cation.

[0155] Example 26: The system of any examples herein, particularly example 25, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCh, MnO, Mn(0H)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, Co3O4, Co(OH)2, C0CI2, NiO, Ni(0H)2, NiCh, CuO, Cu2O, Cu(OH)2, CuCh, ZnO, Zn(OH)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCh, or a combination thereof.

[0156] Example 27: The system of any examples herein, particularly example 25 or example 26, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, FeCh, PbCh, or a combination thereof.

[0157] Example 28: The system of any examples herein, particularly examples 25-27, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, or a combination thereof.

[0158] Example 29: The system of any examples herein, particularly examples 25-28, wherein the salt comprises CaCh, MgCh, or a combination thereof.

[0159] Example 30: The system of any examples herein, particularly examples 25-29, wherein the salt is provided by ocean water, brine, or a combination thereof.

[0160] Example 31 : The system of any examples herein, particularly examples 17-30, wherein the system is configured to performing the methods of any examples herein, particularly examples 1-15. Example 32: The system of any examples herein, particularly examples 16-31, comprising the system shown schematically in Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, or a combination thereof.

[0161] Example 33: The system of any examples herein, particularly examples 16-32, wherein the system further comprises a cation exchange membrane, an anion exchange membrane, a gas diffusion electrode, or a combination thereof.

[0162] Example 34: A method of use of the system of any examples herein, particularly examples 16-33, the method comprising using the system to perform the method of any examples herein, particularly examples 1-15.

[0163] Other advantages which are obvious and which are inherent to the invention will be evident to one skilled in the art. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

[0164] The methods and systems of the appended claims are not limited in scope by the specific methods and systems described herein, which are intended as illustrations of a few aspects of the claims and any methods and systems that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the methods and systems in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative method steps disclosed herein are specifically described, other combinations of the method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

Claims

CLAIMSWhat is claimed is:

1. A method comprising tandem H2 production and CO2 capture and conversion to a carbonate mineral.

2. The method of claim 1, wherein the method is an electrochemical method.

3. The method of claim 1 or claim 2, wherein the method comprises: dissolving CO2 in water and applying an electrochemical potential sufficient to drive the H2 evolution reaction, thereby producing H2 and CCh2'; and contacting the CCh2' with a cation to thereby form an insoluble carbonate compound.

4. The method of claim 3, wherein the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof.

5. The method of claim 3 or claim 4, wherein the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof.

6. The method of any one of claims 3-5, wherein the cation comprises Ca2+, Mg2+, or a combination thereof.

7. The method of any one of claims 3-6, wherein the method further comprises dissolving a salt comprising the cation.

8. The method of claim 7, wherein the salt is dissolved in the presence of the CCh2'.

9. The method of claim 7, wherein, after dissolving the salt, the cation is subsequently contacted with the CCh2'.

10. The method of any one of claims 7-9, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, SrO, Sr(OH)2, SrCl2, BaO, Ba(OH)2, BaCh, MnO, Mn(0H)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, Co3O4, Co(OH)2, C0CI2, NiO, Ni(0H)2, NiCh, CuO, Cu2O, CU(OH)2, CuCh, ZnO, Zn(OH)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCl2, or a combination thereof.

11. The method of any one of claims 7-10, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, FeCh, PbCh, or a combination thereof.

12. The method of any one of claims 7-11, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, or a combination thereof.

13. The method of any one of claims 7-12, wherein the salt comprises CaCh, MgCh, or a combination thereof.

14. The method of any one of claims 7-13, wherein the salt is provided by ocean water, brine, or a combination thereof.

15. The method of any one of claims 1-14, wherein the energy required for H2 production from water is lowered by electrochemically coupling the reaction with the formation of the carbonate mineral.

16. A system for performing the methods of any one of claims 1-15.

17. A system comprising an electrochemical cell comprising: a cathodic compartment comprising CO2 dissolved in water; a power source configured to apply a potential across the system sufficient to drive H2 evolution reaction, thereby producing H2 and CCh2'; an anodic compartment; optionally a mixing compartment; wherein the anodic compartment and / or the mixing compartment comprise an aqueous solution comprising a cation capable of forming an insoluble carbonate compound; and a means for transporting the CCh2' anions and / or the cations, such that the CCh2' anions contact the cations to thereby form an insoluble carbonate compound.

18. The system of claim 17, wherein the CO2 is pre-dissolved in the water.

19. The system of claim 17 or claim 18, wherein the CO2 is directly purged or bubbled in the water within the cathodic compartment.

20. The system of any one of claims 17-19, wherein the means for transporting the CCh2' anions comprises physical mixing, an ion exchange membrane (e.g., a cation exchange membrane), a bipolar membrane, or a combination thereof.

21. The system of any one of claims 17-20, further comprising the mixing compartment, wherein the CCh2' anions contact the cations within the mixing compartment to thereby form the insoluble carbonate compound.

22. The system of any one of claims 17-21, wherein the cation comprises Ca2+, Mg2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, or a combination thereof.

23. The system of any one of claims 17-22, wherein the cation comprises Ca2+, Mg2+, Fe2+, Pb2+, or a combination thereof.

24. The system of any one of claims 17-23, wherein the cation comprises Ca2+, Mg2+, or a combination thereof.

25. The system of any one of claims 17-24, wherein the cation is provided by dissolving a salt comprising the cation.

26. The system of claim 25, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, SrO, Sr(OH)2, SrCh, BaO, Ba(OH)2, BaCh, MnO, Mn(0H)2, MnCh, FeO, Fe2O3, Fe(OH)2, FeCh, CoO, Co3O4, Co(OH)2, C0CI2, NiO, Ni(0H)2, NiCh, CuO, Cu2O, CU(OH)2, CuCh, ZnO, Zn(OH)2, ZnCh, PbO, Pb(OH)2, PbCh, CdO, Cd(OH)2, CdCl2, or a combination thereof.

27. The system of claim 25 or claim 26, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, FeCh, PbCh, or a combination thereof.

28. The system of any one of claims 25-27, wherein the salt comprises CaO, Ca(OH)2, CaCh, MgO, Mg(OH)2, MgCh, or a combination thereof.

29. The system of any one of claims 25-28, wherein the salt comprises CaCh, MgCh, or a combination thereof.

30. The system of any one of claims 25-29, wherein the salt is provided by ocean water, brine, or a combination thereof.

31. The system of any one of claims 17-30, wherein the system is configured to perform the methods of any one of claims 1-15.

32. The system of any one of claims 16-31, comprising the system shown schematically in Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, or a combination thereof.

33. The system of any one of claims 16-32, wherein the system further comprises a cation exchange membrane, an anion exchange membrane, a gas diffusion electrode, or a combination thereof.

34. A method of use of the system of any one of claims 16-33, the method comprising using the system to perform the method of any one of claims 1-15.

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