Low voltage electrolyser and method of use thereof

Abstract

Low voltage electrolyzers and methods and systems for using those low voltage electrolyzers are disclosed herein. In particular, the electrolyzer may include a pH buffer in the catholyte and / or anolyte of the electrolyzer and generate a gas at the cathode or anode that is consumed at the other of the cathode or anode to reduce the open circuit potential.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 366,943, filed on June 24, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to low voltage electrolyzers and systems and methods using the same. More specifically, the present disclosure relates to low voltage electrolyzers in which the cathode electrolyte and / or the anode electrolyte act as a pH buffer and the gas evolved at one electrode is consumed at the other electrode. Background Art

[0004] Electrolyzers use electricity to initiate chemical reactions. In some cases, the products of these reactions can then be sold or used in downstream processes to generate other chemicals and / or products. Summary of the invention

[0005] Disclosed herein are low voltage electrolyzers and systems and methods for using these low voltage electrolyzers. Specifically, due to the reduced voltage required to drive the electrochemical process of the electrolyzer, the electrolyzer disclosed herein may have reduced energy consumption compared to conventional chlor-alkali electrolyzers or other salt splitting electrolyzers. In order to reduce the total voltage required to drive the electrochemical process, the electrolyzer may include a pH buffer in the cathode electrolyte and / or the anode electrolyte and / or be configured so that the gas generated at the cathode or anode compartment can be consumed at another of the cathode or anode compartments to generate acid and / or alkali. The pH buffer may allow the anode electrolyte and / or the cathode electrolyte to help retain the anions and / or cations of the generated acid and / or alkali in the anode electrolyte and / or the cathode electrolyte, rather than allowing these anions and / or cations to pass through the ion selective barrier separating the anode compartment from the cathode compartment. In other words, the pH buffer may reduce or mitigate the migration of protons and / or hydroxides through the ion selective barrier separating the anode compartment from the cathode compartment. This combination of features may allow the electrolyser to operate with significantly lower energy consumption compared to current technology.

[0006] For example, in some embodiments, hydrogen can be generated in the cathode compartment of the electrolyzer and then sent to the anode compartment of the electrolyzer. The hydrogen at the anode compartment can be oxidized to produce hydronium ions or protons, which can be used to generate acids in the anode electrolyte compartment. The pH buffer in the anode electrolyte can help retain those hydronium ions or protons in the anode electrolyte compartment, rather than letting them pass through the ion selective barrier to the cathode electrolyte compartment and lose them. This can reduce the total voltage required to drive the electrochemical process of the electrolyzer.

[0007] In some embodiments, the method includes generating hydrogen in a cathode compartment of an electrolyzer, wherein the cathode compartment includes a cathode electrolyte and a cathode; sending hydrogen to an anode-containing compartment of the electrolyzer, wherein the anode-containing compartment includes an anode and is separated from an anode electrolyte compartment including a pH buffer by a first ion selective barrier, and the anode electrolyte compartment is separated from the cathode compartment by a second ion selective barrier; oxidizing hydrogen in the anode-containing compartment to generate protons; and generating an acid in the anode electrolyte compartment using the protons received through the ion selective barrier. In some embodiments, the open circuit potential of the electrolyzer is less than 1 volt. In some embodiments, the pH buffer includes a weak acid and its conjugate base. In some embodiments, the weak acid includes acetic acid, bicarbonate, or bisulfate, and the conjugate base includes acetate, carbonate, or sulfate. In some embodiments, the method includes dissolving a feedstock material including a target element with an acid and precipitating and / or electrodepositing the target element from the dissolved feedstock material. In some embodiments, the precipitation and / or electrodeposition of the target element from the dissolved feedstock material uses a cathode electrolyte. In some embodiments, the method includes separating hydrogen from the cathode electrolyte. In some embodiments, the method includes capturing acid gas from the gas mixture with a cathode electrolyte and delivering the cathode electrolyte with the captured acid gas to the anode electrolyte compartment. In some embodiments, the method includes generating the acid gas in the anode electrolyte compartment. In some embodiments, the method includes separating the acid gas from the anode electrolyte.

[0008] In some embodiments, the system comprises an electrolyzer, the electrolyzer comprising: a cathode compartment comprising a cathode electrolyte and a cathode; and an anode compartment comprising an anode electrolyte compartment and an anode-containing compartment, the anode electrolyte compartment comprising a pH buffer, the anode-containing compartment comprising an anode, wherein: the cathode compartment is separated from the anode compartment by a first ion selective barrier, and the anode electrolyte compartment is separated from the anode-containing compartment by a second ion selective barrier; the cathode compartment is configured to generate hydrogen; the anode-containing compartment is configured to receive hydrogen and oxidize hydrogen to generate protons; and the anode electrolyte compartment is configured to receive protons passing through the second ion selective barrier and generate acid. In some embodiments, the system includes a dissolution reactor, the dissolution reactor is configured to receive an acid from the anode electrolyte compartment and dissolve a feedstock material comprising a target element. In some embodiments, the system includes a precipitation reactor, the precipitation reactor is configured to receive dissolved feedstock material and precipitate the target element from the dissolved feedstock material. In some embodiments, the system includes a gas / liquid separator configured to receive a cathode electrolyte outlet flow from a cathode compartment and separate the cathode electrolyte outlet flow into hydrogen and a cathode electrolyte. In some embodiments, hydrogen from the gas / liquid separator is sent to a compartment containing an anode. In some embodiments, at least a portion of the cathode electrolyte from the gas / liquid separator is sent to the cathode compartment. In some embodiments, at least a portion of the cathode electrolyte from the gas / liquid separator is sent to a precipitation reactor to precipitate a target element from a dissolved feedstock material. In some embodiments, the system includes an absorber configured to receive a portion of the cathode electrolyte from the gas / liquid separator, receive a gas mixture containing an acidic gas, and capture the acidic gas in the cathode electrolyte. In some embodiments, the cathode electrolyte with captured acidic gas is sent to the anode electrolyte compartment. In some embodiments, the anode electrolyte compartment is configured to generate acidic gas. In some embodiments, the system includes a second gas / liquid separator, which is configured to receive an anode electrolyte product and separate the anode electrolyte product into an acidic gas and an anode electrolyte. In some embodiments, at least a portion of the anolyte from the second gas / liquid separator is sent to the anolyte compartment. In some embodiments, the electrolyzer has an open circuit potential of less than 1 volt. In some embodiments, the pH buffer comprises a weak acid and its conjugate base. In some embodiments, the weak acid comprises acetic acid, bicarbonate or bisulfate, and the conjugate base comprises acetate, carbonate or sulfate.

[0009] In some embodiments, the electrolyzer comprises: a cathode compartment comprising a cathode electrolyte and a cathode; and an anode compartment comprising an anode electrolyte compartment and an anode-containing compartment, the anode electrolyte compartment comprising a pH buffer, the anode-containing compartment comprising an anode, wherein: the cathode compartment is separated from the anode compartment by a first ion selective barrier, and the anode electrolyte compartment is separated from the anode-containing compartment by a second ion selective barrier; the cathode compartment is configured to generate hydrogen; the anode-containing compartment is configured to receive hydrogen and oxidize hydrogen to generate protons; and the anode electrolyte compartment is configured to receive protons passing through the second ion selective barrier and generate acid. In some embodiments, the electrolyzer has an open circuit potential of less than 1 volt. In some embodiments, the pH buffer comprises a weak acid and its conjugate base. In some embodiments, the weak acid comprises acetic acid, bicarbonate, or bisulfate, and the conjugate base comprises acetate, carbonate, or sulfate.

[0010] The embodiments disclosed above are examples only, and the scope of the present disclosure is not limited thereto. Specific embodiments may include all, some or none of the components, elements, features, functions, operations or steps of the embodiments disclosed above. Embodiments according to the present invention are particularly disclosed in the appended claims directed to methods, systems and electrolyzers, wherein any feature mentioned in one claim category (e.g., method) may also be claimed in another claim category (e.g., system). Dependencies or back references in the appended claims are selected only for formal reasons. However, any subject matter obtained by intentional back references to any previous claim (especially multiple dependencies) may also be claimed, so that any combination of claims and their features is disclosed and may be claimed, regardless of the dependencies selected in the appended claims. The subject matter that may be claimed includes not only the combination of features as set forth in the appended claims, but also any other combination of features in the claims, wherein each feature mentioned in the claims may be combined with any other feature or combination of other features in the claims. In addition, any embodiments and features described or depicted herein may be claimed in separate claims and / or in any combination with any embodiment or feature described or depicted herein or with any feature of the appended claims.

[0011] Other advantages will be apparent to those skilled in the art from the following detailed description.The examples and descriptions herein are to be regarded as illustrative rather than restrictive.

[0012] All publications cited in this application, including patent documents, scientific papers, and databases, are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication was individually incorporated by reference. If definitions set forth herein are contrary to or inconsistent with definitions set forth in patents, applications, published applications, and other publications incorporated herein by reference, the definitions set forth herein take precedence over the definitions incorporated herein by reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention will now be described, by way of example only, with reference to the accompanying drawings.

[0014] Figure 1A An example of a dissolution and precipitation system according to some embodiments disclosed herein is illustrated.

[0015] Figure 1B Another example of a dissolution and precipitation system according to some embodiments disclosed herein is illustrated.

[0016] Figure 1C A third example of a dissolution and precipitation system according to some embodiments disclosed herein is illustrated.

[0017] Figure 2 An electrolyzer diagram is illustrated showing example reactions of a dissolution and precipitation system according to some embodiments disclosed herein.

[0018] Figure 3A An example of a gas separation system according to some embodiments disclosed herein is illustrated.

[0019] Figure 3B Another example of a gas separation system according to some embodiments disclosed herein is illustrated.

[0020] Figure 3C A third example of a gas separation system according to some embodiments disclosed herein is illustrated.

[0021] Figure 4 An electrolyzer diagram is illustrated showing example reactions for a gas separation system according to some embodiments disclosed herein.

[0022] Figure 5 An example of a metal leaching system according to some embodiments disclosed herein is illustrated.

[0023] Fig. 6A An example of a silica leaching / upgrading system according to some embodiments disclosed herein is illustrated.

[0024] Figure 6B Another example of a silica leaching / upgrading system according to some embodiments disclosed herein is illustrated.

[0025] Figure 7 An electrolyzer diagram is illustrated showing example reactions of a silica leaching / upgrading system according to some embodiments disclosed herein.

[0026] Figure 8 An exemplary apparatus tested in a laboratory setting to simulate the performance of an electrolyzer described in calcium leaching according to some embodiments disclosed herein is illustrated.

[0027] Fig. 9 Some embodiments disclosed herein are illustrated Figure 8 Measure pH changes of the system's catholyte and anolyte over time.

[0028] Fig.10 Some embodiments disclosed herein are illustrated Figure 8 Variation of the electrolyzer voltage of the system with time.

[0029] Fig.11 An exemplary apparatus tested in a laboratory setting to simulate the performance of an electrolyzer described in gas separation according to some embodiments disclosed herein is illustrated.

[0030] Fig.12 Some embodiments disclosed herein are illustrated Fig.11 Measure pH changes of the system's catholyte and anolyte over time.

[0031] Fig.13 Some embodiments disclosed herein are illustrated Fig.11 Variation of the electrolyzer voltage of the system with time.

[0032] Fig.14 An exemplary apparatus tested in a laboratory setting to simulate the performance of an electrolyzer described in metal leaching according to some embodiments disclosed herein is illustrated.

[0033] Fig.15 Some embodiments disclosed herein are illustrated Fig.14 The CO2 evolution of the system changes with time.

[0034] Fig.16 Some embodiments disclosed herein are illustrated Fig.14 Variation of the electrolyzer voltage of the system with time.

[0035] In the drawings, like reference numerals refer to like parts unless otherwise specified herein. DETAILED DESCRIPTION

[0036] Disclosed herein are low voltage electrolyzers and systems and methods for using these low voltage electrolyzers. Specifically, due to the reduced voltage required to drive the electrochemical process of the electrolyzer, the electrolyzer disclosed herein may have reduced energy consumption compared to conventional chlor-alkali electrolyzers or other salt decomposition electrolyzers. In some embodiments, the electrolyzer disclosed herein may reduce the open circuit potential by about 50% or more and reduce the total energy (compared to conventional chlor-alkali electrolyzers or other salt decomposition electrolyzers). In some embodiments, the efficiency of the electrolyzer disclosed herein may be increased by about 10-40% (compared to conventional chlor-alkali electrolyzers or other salt decomposition electrolyzers). In order to reduce the total voltage required to drive the electrochemical process, the pH buffer in the cathode electrolyte and / or the anode electrolyte can reduce or mitigate the migration of hydronium ions or protons and / or hydroxides through the ion selective barrier separating the anode compartment from the cathode compartment. In addition, the gas generated at the cathode compartment or the anode compartment can be consumed at another electrode to generate acid and / or alkali in the cathode electrolyte or the anode electrolyte. This combination of features may allow the electrolyser to operate with significantly lower energy consumption compared to current technology.

[0037] Examples of electrolyzers that generate acid and / or base and systems for chemical dissolution and precipitation using acid and base are described in U.S. Patent Application No. 62 / 818,604, filed on March 14, 2019; U.S. Patent Application No. 62 / 887,143, filed on August 15, 2019; U.S. Patent Application No. 62 / 962,061, filed on January 16, 2020; PCT Application No. PCT / US2020 / 022672, filed on March 13, 2020; and PCT Application No. PCT / US2020 / 01387, filed on January 16, 2020, all of which are hereby incorporated by reference in their entirety. In addition, an example of an electrochemical reactor for the purpose of cyclic acid gas scrubbing is described in U.S. Patent No. 10,625,209, the entirety of which is hereby incorporated by reference.

[0038] In some embodiments, the chemical reaction initiated by the electrolyzer can be used as a reversible reactant and / or catalytic cycle such as dissolution / precipitation cycle, gas absorption and desorption cycle and / or as a regenerable catalyst. When carrying out the cyclic process, it may be advantageous to minimize the energy consumption of the electrolyzer while still achieving the desired performance. Minimization can be achieved by the efficient design of the electrolyzer (for example, reducing the loss caused by overpotential and ionic resistance) and / or by appropriately selecting the electroactive species reduced in the cathode and oxidized in the anode. An example of energy minimization in the non-cyclic process can be the use of an oxygen depolarized cathode in chlorine production. In the oxygen depolarized cathode, the reaction can consume oxygen, rather than traditional hydrogen generation, thereby resulting in lower energy demand.

[0039] In many cyclic processes, the desired performance can be achieved by sequentially adding acid and then base, or sequentially adding base and then acid. When hydrochloric acid is formed from the hydrogen and chlorine produced from the well-known chlor-alkali process, the acid and base can be generated from the electrolyzer in the process. However, this chlor-alkali process can be highly energy intensive, and the use of an oxygen depolarized cathode can eliminate the necessary hydrogen required to form the hydrochloric acid.

[0040] Other electrolyzer designs based on hydrogen depolarized anodes have been proposed to reduce energy requirements, but these may require the use of both cation and anion exchange membranes and multiple compartments, resulting in significant ohmic potential drops and high energy requirements. One such example is disclosed in U.S. Pat. No. 7,993,500, which is hereby incorporated by reference in its entirety. Additional ion selective membranes and compartments may be required to prevent undesirable back migration of acidic (protons or hydronium ions) and alkaline (hydroxyl ion) species, which would reduce the Faradaic efficiency and increase the overall energy consumption. If additional ion selective membranes and compartments are not added, the maximum concentration of acid and / or base that can be generated may be limited, as shown in data from U.S. Pat. No. 4,561,945 (which is hereby incorporated by reference in its entirety), where only 12% NaOH and 11.1% H2SO4 concentrations were achieved and were achieved at low Faradaic efficiencies (60-80%).

[0041] In addition, Tang et al., Hydrogen-motivated electrolysis of sodium carbonate with extremely low cell voltage (Chemical Communications), February 2018 (the entire text of which is hereby incorporated by reference), also describes a hydrogen depolarized electrode in which sodium hydroxide (NaOH) is produced in the cathode electrolyte and sodium carbonate (Na2CO3) is consumed in the anode electrolyte to produce sodium bicarbonate and / or CO2. This process produces significantly lower energy consumption, but is not a cyclic process and is therefore not suitable for many large-scale processes where the cost of purchasing and / or disposing of byproducts would be prohibitive.

[0042] In some embodiments, the systems disclosed herein may include an electrolyzer. In some embodiments, the electrolyzer may include a cathode compartment and an anode compartment. For example, in the accompanying drawings, electrolyzer 1 may include cathode compartment 2 and anode compartment 3.

[0043] In some embodiments, the anode compartment and the cathode compartment can be separated by an ion selective barrier 6. In some embodiments, the ion selective barrier can be a cation selective barrier or an anion selective barrier. In some embodiments, the cation selective barrier can use sulfonic acid groups, carboxylic acid groups, and / or phosphate groups to create a cation selective environment and include products manufactured by Chemours under the trade name Nafion TM In some embodiments, the anion selective barrier can be a variety of materials. In some embodiments, similarly, the anion selective barrier can use acidic functional groups to create an anion selective environment. In some embodiments, the ion selective barrier can be in the form of a membrane, a supported membrane, a gel, a resin and / or a coating. In some embodiments, the anode compartment and the cathode compartment can be separated by a non-ion selective barrier. Barriers that are not ion selective may be porous or non-porous and may include asbestos diaphragms, Zirfon separators, salt bridges, polymer membranes, gels and / or coatings.

[0044] In some embodiments, the cathode compartment may include a cathode and a cathode electrolyte. In some embodiments, the cathode electrolyte may be a solution in liquid or aqueous form. In some embodiments, the cathode may be in contact with the cathode electrolyte. In some embodiments, the cathode may be immersed in the cathode electrolyte. For example, some of the accompanying drawings illustrate cathodes 4 in cathode compartments. In some embodiments, the cathode compartment may include a cathode-containing compartment containing a cathode and a cathode electrolyte compartment containing a cathode electrolyte. In some embodiments, the cathode-containing compartment and the cathode electrolyte compartment may be separated by an ion or non-ion selective barrier. The ion or non-ion selective barrier may be any of those disclosed herein. In some embodiments, the ion or non-ion selective barrier between the cathode-containing compartment and the cathode electrolyte compartment may prevent the cathode-containing compartment from being flooded by the cathode electrolyte and / or prevent the cathode from being poisoned by the cathode electrolyte. For example, the cathode-containing compartment may be configured to receive a gas (e.g., oxygen), and the barrier may prevent flooding of the cathode-containing gas compartment. In some embodiments, the cathode in the cathode-containing compartment is adjacent to or in direct contact with the ion or non-ion selective barrier between the cathode-containing compartment and the cathode electrolyte compartment.

[0045] In some embodiments, the cathode may support the hydrogen evolution reaction (HER). In some embodiments, the cathode may be a depolarized cathode. In some embodiments, the cathode may be an oxygen depolarized cathode or other gas (e.g., chlorine) depolarized cathode. In some embodiments, the depolarized cathode can reduce the energy demand of the electrolyzer by reducing or eliminating unnecessary energy-intensive net generation of hydrogen. In some embodiments, the cathode may be composed of steel, nickel, carbon, or other conductive materials. In some embodiments, the cathode may be a conductive material known in the art of alkaline electrolyzers that promotes HER, in which hydronium ions and / or water are reduced to form hydrogen, water, and hydroxide ions. In some embodiments, the cathode in contact with the cathode electrolyte may be an electrode suitable for promoting HER as described above, or an oxygen depolarized cathode that consumes oxygen.

[0046] In some embodiments, the cathode electrolyte can be part of the electrolyte adjacent to the cathode. In some embodiments, the cathode electrolyte can include an alkali. In some embodiments, the cathode electrolyte can include a strong base (e.g., an alkali metal base such as sodium hydroxide or potassium hydroxide or an alkaline earth metal base). In some embodiments, the cathode electrolyte and / or the anode electrolyte can act as a pH buffer to prevent significant changes in pH when adding or removing acidic or alkaline components.

[0047] In some embodiments, the cathode electrolyte may include or may be a pH buffer. In some embodiments, the cathode electrolyte may have dissolved components therein, which may act as a pH buffer. The pH buffer may maintain the pH at an almost constant value when a certain amount of acid and / or alkali is added to (or produced in) the pH buffer. In some embodiments, the pH buffer may prevent the pH of the cathode electrolyte from changing significantly when an acidic or alkaline component is added or removed. In some embodiments, the cathode electrolyte may include ammonium acetate.

[0048] In some embodiments, the cathode electrolyte pH buffer may include a weak base and a conjugate acid of a weak base. In some embodiments, the weak base may have a pKa less than or equal to 13 and greater than or equal to 1 or less than or equal to 12 and greater than or equal to 5. In some embodiments, the weak base may include ammonia, amines, carbonates, bicarbonates, dibasic phosphates, tribasic phosphates, borates, thiols, phenols, etc., or a combination thereof. In some embodiments, the conjugate acid may include ammonium, protonated amines, bicarbonates, carbonic acid, dibasic phosphates, monobasic phosphates, boric acid, protonated thiols, and / or phenolates. For example, in some embodiments, the inlet cathode electrolyte of the cathode compartment may include a salt of a weak base (e.g., ammonia), a conjugate acid of a weak base (e.g., ammonium chloride). In some embodiments, the cathode electrolyte may also include an inert dissociated salt to increase the conductivity of the cathode electrolyte. In some embodiments, the inert dissociated salt may be a chloride salt such as sodium chloride or potassium chloride, a nitrate, a sulfate, a perchlorate, etc., and / or a combination thereof. In some embodiments, the fraction of weak base in its conjugate acid form may be greater than about 0%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80% or about 90%. In some embodiments, the fraction of weak base in its conjugate acid form may be less than about 110%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80% or about 90%. In some embodiments, cathode electrolyte and anode electrolyte may be separated by an anion selective barrier that may allow anions such as chloride or nitrate to carry ionic current from the anode electrolyte to the cathode electrolyte.

[0049] In some embodiments, the anode compartment may include an anode and an anode electrolyte. In some embodiments, the anode electrolyte may be a solution in a liquid or aqueous form. In some embodiments, the anode may be in contact with the anode electrolyte. In some embodiments, the anode may be immersed in the anode electrolyte. For example, some drawings illustrate an anode 5 in an anode compartment 3. In some embodiments, the anode compartment may include: an anode-containing compartment (e.g., an anode-containing compartment 7) including an anode and an anode electrolyte compartment (e.g., an anode electrolyte compartment 8) including an anode electrolyte. In some embodiments, the anode-containing compartment and the anode electrolyte compartment may be separated by an ion or non-ion selective barrier (e.g., an ion or non-ion selective barrier 6b). The ion or non-ion selective barrier may be any of those disclosed herein. In some embodiments, the ion or non-ion selective barrier between the anode-containing compartment and the anode electrolyte compartment may prevent the anode-containing compartment from being flooded by the anode electrolyte and / or prevent the anode from being poisoned by the anode electrolyte. For example, the anode-containing compartment may be configured to receive a gas (e.g., hydrogen), and the barrier may prevent the flooding of the anode-containing gas compartment. In some embodiments, the anode in the anode-containing compartment is adjacent to or in direct contact with an ion or non-ion selective barrier located between the anode-containing compartment and the anode electrolyte compartment.

[0050] In some embodiments, the anode can be a hydrogen depolarized anode. In some embodiments, the anode can be an anode similar to the anode present in a proton exchange membrane (PEM) fuel cell. In some embodiments, for example, the anode can oxidize the hydrogen produced in the cathode to produce acidic species, which can convert the salt of the conjugate base of a weak acid (e.g., sodium acetate) into a weak acid (acetic acid). In some embodiments, the anode can include various porous materials, including carbon paper, carbon felt, graphite paper, graphite felt, titanium fabric, titanium felt and / or other porous materials. In some embodiments, the porous anode can be doped with a catalyst, including platinum, ruthenium, nickel or a combination thereof.

[0051] In some embodiments, the depolarized anode may be optionally separated from the anolyte solution by a membrane, an ion selective membrane, a coating or other barrier to prevent flooding of the gas compartment and poisoning of the anode catalyst by the components of the anolyte, as described above. In some embodiments, the anode may support the oxygen evolution reaction (OER) instead of the depolarized anode, which generates oxygen that can be used to depolarize the depolarized cathode. In some embodiments, the anode supporting the OER may be an anode similar to the anode used in an alkaline electrolyzer or a PEM electrolyzer. In some embodiments, the oxygen consumed by the cathode may be all or part of the oxygen generated by the anode, or may be oxygen from another source such as ambient air. In some embodiments, the anode may be a hydrogen depolarized anode as described above or an electrode that promotes OER.

[0052] In some embodiments, the anode and / or cathode can be a depolarized electrode. Examples of such depolarized electrodes can include an oxygen depolarized cathode or a hydrogen depolarized anode. The depolarized electrode can reduce the energy requirements of the battery by eliminating the unnecessary net generation of energy-intensive hydrogen. Those skilled in the art will appreciate that the depolarized electrode can also be used with other gases such as chlorine.

[0053] As described above, at least one of cathode electrolyte or anolyte can act as pH buffer to prevent pH from changing significantly when adding or removing acidic or alkaline components. Low energy consumption can be achieved using pH buffered anolyte and / or cathode electrolyte, because it can prevent or mitigate the significant accumulation of hydronium ions (e.g., protons) and / or hydroxide ions in cathode electrolyte, anolyte or both. The absence of significant accumulation of hydronium ions and / or hydroxide ions can prevent or mitigate the poor reverse migration of these species without adding additional fluid chambers and / or additional ion or non-ion selective barriers. The absence of additional chambers and / or additional barriers can reduce ohmic potential losses. Therefore, in some embodiments, there may be only one anode compartment and one cathode compartment in the electrolyzer. In some embodiments, the faradaic efficiency of the electrolyzer may be higher than about 90%, about 93%, about 95%, about 97%, about 98% or about 99%. In some embodiments, the faradaic efficiency of the electrolyzer may be less than 100%.

[0054] In some embodiments, the cathode electrolyte and the anode electrolyte may have the same or different compositions. In some embodiments, the anode electrolyte may be part of the electrolyte adjacent to the anode. In some embodiments, the anode may include an acid. In some embodiments, the anode electrolyte may include a strong acid. In some embodiments, the anode electrolyte may include or may be a pH buffer. In some embodiments, the anode electrolyte may have dissolved components therein, which may act as a pH buffer. The pH buffer may maintain the pH at an almost constant value when a certain amount of acid and / or base is added to the pH buffer. In some embodiments, the pH buffer may prevent the pH of the anode electrolyte from changing significantly when an acidic or alkaline component is added or removed.

[0055] In some embodiments, the anode electrolyte pH buffer may include a weak acid and a conjugate base of a weak acid. In some embodiments, a weak acid may have a pKa greater than or equal to 1 and less than or equal to 13 or greater than or equal to 1.8 and less than or equal to 12. In some embodiments, a weak acid may include acetic acid, lactic acid, carbonic acid, bicarbonate, carbonate, benzoic acid, bisulfite, bisulfate, monobasic phosphate, dibasic phosphate, tribasic phosphate, citric acid, hydrofluoric acid, oxalic acid, sulfurous acid, etc. or a combination thereof. In some embodiments, a conjugate base may include acetate, citrate, carbonate, bisulfate, monobasic phosphate, dibasic phosphate, tribasic phosphate, oxalate and / or sulfate. For example, in some embodiments, the inlet anode electrolyte of the anode compartment (or the anode electrolyte compartment of the anode compartment) may include a salt of a weak acid (e.g., acetic acid) and a conjugate base of a weak acid (e.g., sodium acetate). In some embodiments, the anode electrolyte may also include an inert dissociated salt to increase the conductivity of the anode electrolyte. In some embodiments, inert dissociated salts may include sodium chloride or potassium chloride salts, nitrates, sulfates, perchlorates, etc. and / or combinations thereof. In some embodiments, the anode electrolyte may contain other additives such as surfactants, reducing agents, oxidants, antimicrobial agents, etc. or combinations thereof. In some embodiments, the fraction of weak acid in the form of its conjugate base may be greater than about 0%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90%. In some embodiments, the fraction of weak acid in the form of its conjugate base may be less than about 100%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90%. In some embodiments, the cathode electrolyte and the anode electrolyte may be separated by a cation selective barrier that will allow cations such as sodium or potassium to carry ionic current from the anode electrolyte to the cathode electrolyte. In some embodiments, the cathode electrolyte and the anode electrolyte may be buffered as described above. In some embodiments, the buffer component may be the same in the cathode electrolyte and the anode electrolyte or may differ between the two.

[0056] In some embodiments, the cathode compartment can be configured to generate gas. In some embodiments, the gas can include hydrogen. In some embodiments, the anode compartment can be configured to receive gas and oxidize gas, thereby generating hydronium ions and / or protons. In some embodiments, the anode-containing compartment of the anode compartment can be configured to receive gas and oxidize gas, thereby generating hydronium ions and / or protons. In some embodiments, the anode compartment can generate acid with hydronium ions and / or protons. In some embodiments, the anode electrolyte compartment of the anode compartment is configured to receive hydronium ions and / or protons through an ion selective barrier and generate acid.

[0057] For example, Figure 2 , 4 7 and 8 illustrate exemplary electrolyzer diagrams showing various example reactions that may occur in the electrolyzer. These diagrams include at least one anode electrolyte inlet stream 9, at least one cathode electrolyte inlet stream 11, at least one anode electrolyte outlet stream 10, at least one cathode electrolyte outlet stream 12, and at least one gas inlet stream 13. Thus, in some embodiments, the anode compartment can receive at least one anode electrolyte inlet stream and have at least one anode electrolyte outlet stream. In some embodiments, the anode electrolyte compartment of the anode compartment can receive the at least one anode electrolyte inlet stream and have the at least one anode electrolyte outlet stream. In other words, the anode electrolyte compartment (and cathode compartment or cathode electrolyte compartment) can act as a flow chamber. In some embodiments, the anode compartment can receive the at least one gas inlet stream. In some embodiments, the anode-containing compartment of the anode compartment can receive the at least one gas inlet stream.

[0058] like Figure 2 , 4 As shown in Figures 1 and 7, in some embodiments, an oxidation reaction may occur in the anode compartment (e.g., at the anode of the anode compartment), and in some embodiments, a reduction reaction may occur in the cathode compartment (e.g., at the cathode of the cathode compartment). In some embodiments, the cathode electrolyte may be in direct contact with the cathode or in contact with the cathode through a barrier. In some embodiments, the anode electrolyte may be in direct contact with the anode or in contact with the anode through a barrier.

[0059] In some embodiments, the cathode compartment can receive at least one cathode electrolyte inlet flow and have at least one cathode electrolyte outlet flow. In some embodiments, the cathode electrolyte compartment of the cathode compartment can receive the at least one cathode electrolyte inlet flow and have the at least one cathode electrolyte outlet flow. In other words, the cathode electrolyte compartment can act as a flow chamber. In some embodiments, the cathode compartment can receive the at least one gas inlet flow. In some embodiments, the cathode-containing compartment of the cathode compartment can receive the at least one gas inlet flow.

[0060] In some embodiments, the at least one anode electrolyte inlet stream may have a higher pH than the at least one anode electrolyte outlet stream. In some embodiments, the at least one anode electrolyte outlet stream may have a pH of less than 6. In other words, an acid may be generated in the anode compartment so that the anode electrolyte may have a lower pH when leaving the anode compartment. In some embodiments, the at least one cathode electrolyte inlet stream may have a lower pH than the at least one cathode electrolyte outlet stream. In some embodiments, the at least one cathode electrolyte outlet stream may have a pH higher than 7. In other words, a base may be generated in the cathode compartment so that the cathode electrolyte may have a higher pH when leaving the cathode compartment. In some embodiments, the at least one anode electrolyte inlet stream may have a lower pH than the at least one anode electrolyte outlet stream, and the at least one cathode electrolyte inlet stream may have a higher pH than the at least one cathode electrolyte outlet stream.

[0061] In some embodiments, the anode compartment can be configured to generate gas. In some embodiments, the gas can include oxygen. In some embodiments, the cathode compartment can be configured to receive gas and reduce gas, thereby generating hydroxide ions. In some embodiments, the cathode-containing compartment of the cathode compartment can be configured to receive gas and reduce gas, thereby generating hydroxide ions. In some embodiments, the cathode compartment can generate alkali with hydroxide ions. In some embodiments, the cathode electrolyte compartment of the cathode compartment is configured to receive hydroxide ions through the ion selective barrier and generate alkali.

[0062] In some embodiments, the gas (e.g., hydrogen) generated in the cathode compartment can be sent to the compartment containing the anode. In some embodiments, the gas generated in the cathode compartment can be consumed in the anode compartment. In some embodiments, the gas generated in the cathode compartment can be oxidized in the anode compartment. In some embodiments, the oxidized gas can generate hydronium ions and / or protons. In some embodiments, hydronium ions and / or protons can be used to generate acid. In some embodiments, the acid generated can be any acid disclosed herein (e.g., strong acid and / or weak acid). In some embodiments, the acid generated can be formed by the conjugate base reaction of hydronium ions and / or protons with the weak acid in the anode electrolyte. In some embodiments, acid can be generated in the anode electrolyte compartment after receiving hydronium ions and / or protons through the barrier between the anode electrolyte compartment and the compartment containing the anode in the anode compartment.

[0063] In some embodiments, the gas (e.g., oxygen) generated in the anode compartment can be sent to the compartment containing the cathode. In some embodiments, the gas generated in the anode compartment can be consumed in the cathode compartment. In some embodiments, the gas generated in the anode compartment can be reduced in the anode compartment. In some embodiments, the reduced gas can generate hydroxide ions. In some embodiments, the hydroxide ions can be used to generate alkali. In some embodiments, the alkali generated can be any alkali disclosed herein (e.g., strong base and / or weak base). In some embodiments, the alkali generated can be formed by the conjugate acid reaction of hydroxide ions with the weak base in the cathode electrolyte. In some embodiments, alkali can be generated in the cathode electrolyte compartment after receiving hydroxide ions that pass through the barrier between the cathode electrolyte compartment and the compartment containing the cathode in the cathode compartment.

[0064] Without being bound by any particular theory or explanation, the electrolyzer designed herein may have reduced energy consumption compared to conventional chlor-alkali electrolyzers or other salt decomposition electrolyzers due to the reduced voltage required to drive the electrochemical process. For example, before considering the overpotential (also called the open circuit potential), the voltage required to drive the chlor-alkali electrolyzer is about 2.2 volts. In some embodiments, the open circuit potential may refer to the decomposition voltage, before or without the overpotential. In contrast, in some embodiments, the open circuit potential to drive the electrolyzer as described herein can be estimated to be about 70 mV multiplied by the pH difference between the cathode electrolyte and the anode electrolyte at a typical operating temperature. For example, the expected voltage of a system operating with concentrated sodium hydroxide (pH = 15) in the cathode electrolyte and a mixture of acetic acid and sodium acetate (pH = 4.5) in the anode electrolyte is expected to be around 0.74 volts, or one-third of the voltage of the chlor-alkali electrolyzer. In some embodiments, depending on the pH difference between the anode electrolyte and the cathode electrolyte, the open circuit potential of the electrolyzer described herein may be less than about 0.2 volts, about 0.5 volts, about 1 volt, or about 2 volts. In some embodiments, the open circuit potential of an electrolyzer described herein may be greater than about 0.001 volts, about 0.05 volts, about 0.1 volts, about 0.2 volts, or about 0.5 volts.

[0065] As described above, pH buffered electrolyzers (i.e., the cathode electrolyte and / or the anode electrolyte act as a pH buffer) can significantly reduce the undesirable migration of acidic and / or alkaline streams across between the anode electrolyte and the cathode electrolyte, thereby improving the current efficiency of the electrolyzer. Current efficiency may sometimes be referred to as Faraday efficiency.

[0066] Depending on the choice of buffered electrolyte (e.g., cathode electrolyte and / or anolyte), the electrolyzer may have certain other advantages in terms of selectivity of the separation process, in addition to energy consumption, compared to electrolyzers that generate strong acids and strong bases (such as chlor-alkali processes). For example, as further described herein, weak acids may selectively dissolve some components of minerals or ash (such as calcium), but will not significantly dissolve other metals (such as iron or aluminum). Similarly, electrolyzers that generate weak bases (such as ammonia or amines) may be able to precipitate some materials (e.g., magnesium hydroxide), but not other materials (such as calcium hydroxide). For gas scrubbing, depending on the weak base selected, it may absorb some acidic gases (such as sulfur dioxide), but not other gases (such as carbon dioxide).

[0067] In addition, it is well known that electrolyzers (such as chlor-alkali electrolyzers) are extremely sensitive to certain impurities (such as calcium cations). Due to the different pH of the electrolyte and the presence of certain buffer salts, the electrolyzers described herein may be less susceptible to contamination by certain impurities. Similarly, due to the presence of less corrosive electrolytes, the electrolyzers may be less susceptible to corrosion during sudden power outages and / or during power cycle operations. In some embodiments, it may be desirable to operate the power cycle during a period of using a cheaper and / or less carbon-intensive source of electricity.

[0068] In some embodiments, the equipment capital cost of the electrolyzer disclosed herein may be lower than other electrochemical systems (such as chlor-alkali electrolyzers) for acid and base production. In some embodiments, the electrolyzer disclosed herein may produce weak acids and / or weak bases. In some embodiments, the electrolyzer disclosed herein may produce acids and / or bases of moderate concentrations or moderate pH values, such as bases of pH <14, pH <13, pH <12, pH <11, or pH <10, and / or acids of pH>0, pH>1, pH>2, pH>3, and / or pH>4. In some embodiments, relatively inexpensive materials of construction may be able to prevent corrosion and / or other forms of degradation or damage to the electrolyzer. Although chlor-alkali electrolyzers may require expensive, difficult to machine or manufacture metals or alloys such as titanium, titanium alloys, or nickel alloys, may require precious metal coatings on these alloys to prevent oxygen evolution, and may require piping made of expensive chlorine-compatible fiber-reinforced plastics (FRPs), the electrolyzers disclosed herein can be made of cheaper, more easily machined / manufactured materials such as carbon steel, stainless steel, graphite, or cheaper plastics (with or without fiber reinforcement), or combinations thereof.

[0069] The acid and / or base generated from the electrolyzer disclosed herein can be used to perform many different cyclic processes, including dissolution, precipitation, electrodeposition, gas absorption, liquid extraction, solute extraction, reaction catalysis and / or neutralization. In some embodiments, once the acid and base are mixed to produce a neutralized solution, the solution can be used in whole or in part as a feed to the cathode and / or anode compartment. In some embodiments, the electrolyzer disclosed herein can be used for several electrolyte treatment steps, including but not limited to precipitation, clarification, filtration, ion exchange, activated carbon treatment, evaporation, gas stripping and / or the placement of additive chemicals.

[0070] In some embodiments, the acidic (e.g., weak or strong acid) anolyte produced by the electrolyzer disclosed herein can be used to dissolve solids (soluble in acid), absorb gases (soluble in acid), extract liquids (soluble in acid), extract solutes (soluble in acid), serve as an anti-solvent to precipitate solids, catalyze reactions accelerated by the presence of acid, and / or neutralize the generated base. In some embodiments, the acidic anolyte produced by the electrolyzer disclosed herein can be used to neutralize the base (e.g., weak or strong base) generated after using a base to dissolve solids (soluble in base), absorb gases (soluble in base), extract liquids (soluble in base), extract solutes (soluble in base), serve as an anti-solvent to precipitate solids, or catalyze reactions accelerated by the presence of base. In some embodiments, the alkaline (e.g., weak or strong base) cathode electrolyte produced by the electrolyzer disclosed herein can be used to dissolve solids (soluble in base), absorb gases (soluble in base), extract liquids (soluble in base), extract solutes (soluble in base), use as an anti-solvent to precipitate solids, catalyze reactions accelerated by the presence of base, and / or neutralize the generated acid. In some embodiments, the alkaline cathode electrolyte produced by the electrolyzer disclosed herein can be used to neutralize the acid (e.g., weak or strong acid) generated after using an acid to dissolve solids (soluble in acid), absorb gases (soluble in acid), extract liquids (soluble in acid), extract solutes (soluble in acid), use as an anti-solvent to precipitate solids, or catalyze reactions accelerated by the presence of acid.

[0071] In some embodiments, if an acidic anolyte is used to perform the task, it may be neutralized by a base from the cathode electrolyte, or if an alkaline cathode electrolyte is used to perform the task, it may be neutralized by an acidic anolyte. In some embodiments, the neutralized mixture can then be used in whole or in part as a feed to the cathode compartment and / or the anode compartment (e.g., the at least one cathode electrolyte inlet stream and / or the at least one anode electrolyte inlet stream).

[0072] Some embodiments disclosed herein may allow for the dissolution of metal oxides from limestone (high calcium, dolomitic or magnesian), dolomite, calcite, aragonite, wollastonite, fly ash, bottom ash, pond ash, blast furnace slag, high oxygen furnace slag, electric arc furnace slag, slag from municipal waste, olivine, and / or other similar sources (such as waste and mined rocks).

[0073] Some embodiments disclosed herein may be directed to an electrolyzer having a weakly acidic carbonate or bicarbonate anode electrolyte and a strong base cathode electrolyte, which can be used to capture carbon dioxide from a dilute stream including ambient air. In some embodiments, a strong base can be contacted with a flowing air stream to produce a weakly acidic solution of carbonates and bicarbonates. Carbonates / bicarbonates can then be supplied in part or in whole as an anode electrolyte stream of a weakly acidic electrolyzer. As the anode electrolyte is acidified, bicarbonates and carbonates can be converted into carbonic acid, which can result in the precipitation of carbon dioxide, which can be captured as a nearly pure stream to be sealed or utilized in a manner well known to those skilled in the art. The decarbonized anode electrolyte can then be returned to the cathode compartment, where it can partially or completely form at least one cathode electrolyte inlet stream to be converted back to a strong base. In some embodiments, some buffered electrolytes (anode electrolytes and / or cathode electrolytes) in the anode electrolyte, cathode electrolyte, or both suitable for use in the present invention can contain dissolved gases (carbon dioxide, sulfur dioxide, ammonia, chlorine, etc.), which can be absorbed and evaporated, or can be solids in a similarly dissolved form, which can be dissolved and precipitated. Other buffered electrolytes may be soluble in the anolyte and / or catholyte but are less likely to evaporate or precipitate, such as acetates, citrates, ethanolamines, phenols, benzoates, chlorates, hypochlorites, and / or phosphates.

[0074] Similar to the examples described above using carbon dioxide, some embodiments disclosed herein may include regenerating a desulfurization absorbent such as lime, limestone and / or amines by acidifying the spent absorbent in the anode compartment and / or by releasing the captured sulfur as sulfur dioxide through contact with the anode electrolyte and then regenerating the desulfurized absorbent in the cathode compartment.

[0075] In some embodiments, one or more reactors or one or more electrolyzers can be operated using intermittent renewable electricity. In some embodiments, the acid and / or base stream produced by the electrolyzer can be stored for later use. In some embodiments, electricity can be used to operate the reactor and produce acid and / or base when low cost, which can be stored and used to operate the chemical dissolution and precipitation process when electricity cost is high.

[0076] In some embodiments, the methods disclosed herein may include dissolving a feedstock material comprising a target element and precipitating (and / or electrodepositing) the target element from the feedstock material. In some embodiments, the feedstock material may be dissolved using an acid and / or base generated by an electrolyzer disclosed herein. In some embodiments, the acid and / or base may be in an anode electrolyte and / or cathode electrolyte from an electrolyzer disclosed herein. In some embodiments, the target element may be precipitated (and / or electrodeposited) from the dissolved feedstock material using an acid and / or base generated by an electrolyzer disclosed herein. In some embodiments, the acid and / or base may be in an anode electrolyte and / or cathode electrolyte from an electrolyzer disclosed herein.

[0077] In some embodiments, the feedstock material may be a calcium salt such as calcium carbonate (e.g., CaCO3), calcium silicate (e.g., CaSiO3), calcium aluminosilicate, slag, ash, recycled concrete, reclaimed concrete, minerals, etc., and / or combinations thereof. In some embodiments, the target material may be calcium (to form calcium hydroxide), magnesium (to form magnesium hydroxide), high-value metals (e.g., nickel, copper, or manganese), and / or silicon dioxide. In some embodiments, two or more products may be produced based on separation of insoluble materials and selective precipitation and / or electrodeposition of multiple dissolved compounds.

[0078] Figures 1A-1C A system for dissolving and precipitating feedstock materials using an electrolyzer disclosed herein according to some embodiments may be illustrated. In some embodiments, Figure 2 An electrolyzer diagram is illustrated, showing example reactions that can be used in the dissolution and precipitation of feedstock materials. In some embodiments, the electrolyzer 1 may include an anode 5 (e.g., a depolarized anode) in an anode-containing compartment 7 of the anode compartment 3. In some embodiments, the anode may be separated from the anode electrolyte compartment 8 (e.g., a flow chamber) via a barrier 6b (e.g., a cation selective membrane). In some embodiments, the anode electrolyte compartment includes an anode electrolyte comprising a weak acid (e.g., acetic acid) and its conjugate base (e.g., sodium acetate). In some embodiments, the anode compartment is separated from the cathode compartment 2 via a barrier 6 (e.g., a cation selective membrane). In some embodiments, the cathode compartment includes a cathode electrolyte comprising an alkali (e.g., sodium hydroxide) and a cathode 4. In some embodiments, the cathode compartment may support a gas generation reaction (e.g., a hydrogen evolution reaction). In some embodiments, the electrolyzer may include a power source (e.g., power source 14) that can power the electrolyzer.

[0079] In some embodiments, the gas generated by the reaction at the cathode can leave the electrolyzer together with at least one cathode electrolyte outlet stream 12 (i.e., cathode electrolyte product stream). In some embodiments, the system may include a gas / liquid separator 15 configured to separate gas from liquid. In some embodiments, the gas / liquid separator may be configured to receive the at least one cathode electrolyte outlet stream and separate the gas (e.g., hydrogen) from the cathode electrolyte (e.g., sodium hydroxide). In some embodiments, the separated gas (e.g., at least one gas inlet stream 13) from the cathode electrolyte outlet stream can be sent to the anode compartment (e.g., a compartment containing an anode). In some embodiments, the gas can be sent to the anode compartment (if there is no anode-containing compartment, then to the anode electrolyte compartment) so that it bubbles into the anode compartment. In some embodiments, the separated gas (e.g., hydrogen) can be oxidized by the anode to generate hydronium ions and / or protons. In some embodiments, these hydronium ions and / or protons can be transferred through the barrier 6b separating the anode-containing compartment and the anode electrolyte compartment. In some embodiments, the hydronium ions and / or protons can react with the anode electrolyte (e.g., the conjugate base of the anode electrolyte (e.g., sodium acetate)) to form an acid (e.g., acetic acid). In some embodiments, the at least one anode electrolyte outlet stream 10 can comprise a lower pH than the at least one anode electrolyte inlet stream 9. In some embodiments, the at least one anode electrolyte outlet stream 10 can comprise a weak acid (e.g., acetic acid) wherein the amount of residual conjugate base (e.g., sodium acetate) is lower than the at least one anode electrolyte inlet stream. In some embodiments, the cathode compartment can be configured to receive at least a portion of the separated cathode electrolyte from the gas / liquid separator as the at least one cathode electrolyte inlet stream 11.

[0080] In some embodiments, the system may include at least one dissolution reactor 16. In some embodiments, a raw material material 17 containing a target element may be dissolved in the at least one dissolution reactor. In some embodiments, the at least one anode electrolyte outlet stream may be mixed with the raw material in the at least one dissolution reactor. In some embodiments, the at least one dissolution reactor may be configured to receive the raw material and the at least one anode electrolyte outlet stream (i.e., the anode electrolyte product stream). In some embodiments, at least a portion of the raw material (e.g., at least the target material) may be dissolved by the anode electrolyte outlet stream (e.g., acetic acid) in the at least one dissolution reactor (e.g., calcium is dissolved into calcium acetate). In some embodiments, the acid generated in the anode compartment may be used to dissolve at least a portion of the raw material. In some embodiments, during the dissolution process, some products may be removed in the waste stream 18. For example, if the raw material material is carbonated (e.g., calcium carbonate), carbon dioxide may be formed during the dissolution process and may leave in the waste stream. In some embodiments, if the raw material material includes silicon, silicon oxide (e.g., silicon dioxide) may be formed during the dissolution process and may leave in the waste stream.

[0081] In some embodiments, the system may include at least one precipitation reactor 19. In some embodiments, a portion of the dissolved feedstock material 20 (e.g., dissolved target material) may be sent to the at least one precipitation reactor. In some embodiments, the at least one precipitation reactor may precipitate components of the dissolved feedstock material. In some embodiments, the at least one precipitation reactor may be configured to receive a portion of the separated cathode electrolyte 21 (e.g., sodium hydroxide) and precipitate the target element from the dissolved feedstock material. In some embodiments, the at least one precipitation reactor is configured to receive a portion of the separated cathode electrolyte from the gas / liquid separator. In some embodiments, the portion of the separated cathode electrolyte (e.g., sodium hydroxide) from the gas / liquid separator may be mixed with the dissolved feedstock material (e.g., calcium acetate) to precipitate the target material (e.g., calcium hydroxide). As described above, a portion of the separated cathode electrolyte from the gas / liquid separator may be recycled back to the at least one cathode electrolyte inlet stream as the cathode compartment. In some embodiments, the reaction between the separated cathode electrolyte (e.g., sodium hydroxide) and the dissolved feedstock material (e.g., calcium acetate) may precipitate the target material 22 (e.g., calcium in the form of calcium hydroxide), which may be removed as a slurry in some embodiments. In some embodiments, the overflow of the at least one precipitation reactor may be sent to the anode compartment to serve as the at least one anode electrolyte inlet stream.In some embodiments, depending on the dissolved salts, various solids may be recovered as target materials, such as silica.

[0082] Although the above description describes that the gas is generated in the cathode compartment and oxidized in the anode compartment, wherein the dissolution is completed by the acid formed in the anode compartment, in some embodiments, the system can be used to generate gas (e.g., oxygen) in the anode compartment and reduce in the cathode compartment, wherein the dissolution is completed by the base formed in the cathode compartment (and the precipitation reaction is caused by the acid from the anode compartment). In other words, the system described in conjunction with the accompanying drawings can also be applied to alkaline dissolution and acid precipitation reactions, wherein the gas / liquid separator is fluidly connected to the anode compartment. Therefore, the at least one dissolution reactor can be fluidly connected to the anode compartment (or anode electrolyte compartment) and / or the cathode compartment (or cathode electrolyte compartment), the at least one precipitation reactor can be fluidly connected to the anode compartment (or anode electrolyte compartment) and / or the cathode compartment (or cathode electrolyte compartment), the gas / liquid separator can be fluidly connected to the anode compartment (or anode electrolyte compartment or anode-containing compartment) and / or cathode compartment (or cathode electrolyte compartment or cathode-containing compartment), and / or the at least one precipitation reactor can be fluidly connected to the gas / liquid separator.

[0083] In some embodiments, the methods disclosed herein may include capturing gases (e.g., acid gases) from a gas mixture. In other words, the methods disclosed herein may include a gas separation process (e.g., a carbon dioxide gas separation process). In some embodiments, the acid gas may be carbon dioxide, sulfur dioxide, and / or hydrogen sulfide. In some embodiments, the gas mixture may be air (e.g., ambient air), post-combustion gas, natural gas, and / or other hydrocarbon vapors. In some embodiments, the gas may be an alkaline gas, such as ammonia and / or methylamine.

[0084] Figures 3A-3C A system for performing a gas separation process using an electrolyzer disclosed herein according to some embodiments may be illustrated. In some embodiments, Figure 4 An electrolyzer diagram is illustrated, which shows an example reaction that can be used in a gas separation process. In some embodiments, the electrolyzer 1 may include an anode electrolyte compartment 8 containing an anode electrolyte (e.g., an aqueous solution of potassium bicarbonate), separated from an anode-containing compartment 7 by a barrier 6b (e.g., a cation selective membrane). In some embodiments, the anode electrolyte may include a weak acid (e.g., potassium bicarbonate) and its conjugate base (e.g., potassium carbonate). In some embodiments, the anode-containing compartment 8 may include an anode 5 (e.g., a porous platinum-containing carbon anode). In some embodiments, the anode compartment 3 may be separated from the cathode compartment 2 via a barrier 6 (e.g., a cation selective membrane). In some embodiments, the cathode compartment may include a cathode electrolyte containing an alkali (e.g., potassium hydroxide) and a (contacting) cathode 4 (e.g., a porous nickel cathode) (which may support HER reactions). In some embodiments, a power source 14 may supply power to the electrolyzer.

[0085] In some embodiments, the gas generated by the reaction at the cathode can leave the electrolyzer together with at least one cathode electrolyte outlet stream 12 (i.e., cathode electrolyte product stream). In some embodiments, the system may include a gas / liquid separator 15 configured to separate gas from liquid. In some embodiments, the gas / liquid separator may be configured to receive the at least one cathode electrolyte outlet stream and separate the gas (e.g., hydrogen) from the cathode electrolyte (e.g., potassium hydroxide). In some embodiments, the separated gas (e.g., at least one gas inlet stream 13) from the cathode electrolyte outlet stream can be sent to the anode compartment (e.g., a compartment containing an anode). In some embodiments, the gas can be sent to the anode compartment (if there is no anode-containing compartment, then to the anode electrolyte compartment) so that it bubbles into the anode compartment. In some embodiments, the separated gas (e.g., hydrogen) can be oxidized by the anode to generate hydronium ions and / or protons. In some embodiments, these hydronium ions and / or protons can be transferred through the barrier 6b separating the anode-containing compartment and the anode electrolyte compartment. In some embodiments, the hydronium ions and / or protons can react with the anode electrolyte (e.g., the conjugate base of the anode electrolyte (e.g., potassium carbonate)) to form an acid (e.g., potassium bicarbonate). In some embodiments, the at least one anode electrolyte outlet stream 10 can comprise a lower pH than the at least one anode electrolyte inlet stream 9. In some embodiments, the at least one anode electrolyte outlet stream 10 can comprise a weak acid (e.g., potassium bicarbonate) wherein the amount of residual conjugate base (e.g., potassium carbonate) is lower as compared to the at least one anode electrolyte inlet stream. In some embodiments, the cathode compartment can be configured to receive at least a portion of the separated cathode electrolyte from the gas / liquid separator as the at least one cathode electrolyte inlet stream 11.

[0086] In some embodiments, the system may include at least one gas absorber 24 (e.g., a packed bed absorber) configured to receive a gas mixture 25 (e.g., air, flue gas, exhaust gas, CO2-rich gas, etc.). In some embodiments, the gas absorber can remove the target gas (e.g., acid gas) from the gas mixture. In some embodiments, the gas absorber can capture the gas (e.g., acid gas) in the liquid. In some embodiments, the at least one gas absorber can be configured to receive a portion of the separated cathode electrolyte (e.g., potassium hydroxide) from the gas / liquid separator. In some embodiments, the at least one gas absorber can be configured to capture acidic gas in the separated cathode electrolyte from the gas / liquid separator. In some embodiments, the separated cathode electrolyte portion from the gas / liquid separator can be sent to the top of the absorber, where it contacts the gas mixture (e.g., a gas stream containing carbon dioxide, such as air or industrial process gas) in countercurrent. Clean gas or lean gas 26 from which most of the target gas (e.g., carbon dioxide) has been removed can leave the absorber. In some embodiments, the cathode electrolyte in the absorber can capture the target gas. For example, potassium hydroxide may be carbonated to form a mixture of residual potassium hydroxide, potassium carbonate, and potassium bicarbonate.

[0087] In some embodiments, the captured target gas stream 27 can be sent to the anode compartment (the anode electrolyte compartment of the anode compartment) and / or the cathode compartment. In some embodiments, the captured target gas stream can be one of the anode electrolyte inlet streams 9. As described above, in some embodiments, the separated gas (e.g., hydrogen) can be oxidized at the anode to generate hydronium ions and / or protons. In some embodiments, these hydronium ions and / or protons can be transferred through the barrier 6b separating the anode-containing compartment from the anode electrolyte compartment. In some embodiments, the anode compartment (or the anode electrolyte compartment of the anode compartment) can be configured to generate gas (e.g., acidic gas). In some embodiments, the hydronium ions and / or protons can react with the anode electrolyte (e.g., acidification), thereby releasing gas (e.g., carbon dioxide) from the anode electrolyte.

[0088] In some embodiments, the gas generated in the anode electrolyte can leave the electrolyzer together with the at least one anode electrolyte outlet stream 10. In some embodiments, the system may include another gas / liquid separator 15b configured to separate the gas from the liquid. In some embodiments, the gas / liquid separator can be configured to receive the at least one anode electrolyte outlet stream and separate the gas (e.g., acidic gas such as carbon dioxide) from the anode electrolyte (e.g., potassium bicarbonate, potassium carbonate and / or an inert electrolyte such as sodium chloride / potassium chloride). In some embodiments, the separated gas 28 (e.g., acidic gas) from the anode electrolyte outlet stream can be sent for purification, compression, storage and / or utilization. In some embodiments, the cathode compartment and / or the anode compartment can be configured to receive at least a portion of the separated anode electrolyte from the gas / liquid separator as the at least one anode electrolyte inlet stream 9 and / or the at least one cathode electrolyte inlet stream 11.

[0089] In some embodiments, any gas / liquid separator can be fluidly connected to the anode compartment (or anode electrolyte compartment or anode-containing compartment) and / or cathode compartment (or cathode electrolyte compartment or cathode-containing compartment). In some embodiments, the gas absorber can be fluidly connected to the gas / liquid separator, cathode compartment (or cathode electrolyte compartment or cathode-containing compartment) and / or anode compartment (or anode electrolyte compartment or anode-containing compartment).

[0090] As described above, in some embodiments, the methods disclosed herein may include dissolving a feedstock material comprising a target element and precipitating (and / or electrodepositing) the target element from the feedstock material. In some embodiments, the feedstock material may be dissolved using an acid and / or base generated by an electrolyzer disclosed herein. In some embodiments, the acid and / or base may be in an anode electrolyte and / or cathode electrolyte from an electrolyzer disclosed herein. In some embodiments, the target element may be precipitated (and / or electrodeposited) from the dissolved feedstock material using an acid and / or base generated by an electrolyzer disclosed herein. In some embodiments, the acid and / or base may be in an anode electrolyte and / or cathode electrolyte from an electrolyzer disclosed herein.

[0091] In some embodiments, the feedstock material may be a metal ore, such as copper ore, nickel ore, olivine, slag, ash, laterite, and / or a combination thereof. In some embodiments, the metal ore may include copper, nickel, iron, manganese, calcium, aluminum, magnesium, silicon, and / or a combination thereof. In some embodiments, the target material may be a metal in a metal ore, such as nickel, copper, or a combination thereof.

[0092] Figure 5A system for performing a metal leaching process using an electrolyzer disclosed herein according to some embodiments is illustrated. In some embodiments, the electrolyzer 1 may include an anode (e.g., a depolarized anode) in an anode-containing compartment 7 of the anode compartment 3. In some embodiments, the anode may be separated from the anode electrolyte compartment 8 (e.g., a flow chamber) via a barrier 6b (e.g., a cation selective membrane). In some embodiments, the anode electrolyte compartment includes an anode electrolyte comprising a weak acid (e.g., sodium bisulfate) and its conjugate base (e.g., sodium sulfate). In some embodiments, the anode compartment is separated from the cathode compartment 2 via a barrier 6 (e.g., a cation selective membrane). In some embodiments, the cathode compartment includes a cathode electrolyte comprising an alkali (e.g., sodium hydroxide) and a cathode 4. In some embodiments, the cathode compartment may support a gas generation reaction (e.g., a hydrogen evolution reaction). In some embodiments, the electrolyzer may include a power supply that can supply power to the electrolyzer.

[0093] In some embodiments, the gas generated by the reaction at the cathode can leave the electrolyzer together with at least one cathode electrolyte outlet stream 12 (i.e., cathode electrolyte product stream). In some embodiments, the system may include a gas / liquid separator 15 configured to separate gas from liquid. In some embodiments, the gas / liquid separator may be configured to receive the at least one cathode electrolyte outlet stream and separate the gas (e.g., hydrogen) from the cathode electrolyte (e.g., sodium hydroxide). In some embodiments, the separated gas (e.g., at least one gas inlet stream 13) from the cathode electrolyte outlet stream can be sent to the anode compartment (e.g., a compartment containing an anode). In some embodiments, the gas can be sent to the anode compartment (if there is no anode-containing compartment, then to the anode electrolyte compartment) so that it bubbles into the anode compartment. In some embodiments, the separated gas (e.g., hydrogen) can be oxidized by the anode to generate hydronium ions and / or protons. In some embodiments, these hydronium ions and / or protons can be transferred through the barrier 6b separating the anode-containing compartment and the anode electrolyte compartment. In some embodiments, the hydronium ions and / or protons can react with the anode electrolyte (e.g., the conjugate base of the anode electrolyte (e.g., sodium sulfate)) to form an acid (e.g., sodium bisulfate). In some embodiments, the at least one anode electrolyte outlet stream 10 can comprise a lower pH than the at least one anode electrolyte inlet stream. In some embodiments, the at least one anode electrolyte outlet stream 10 can comprise a weak acid (e.g., sodium bisulfate) wherein the amount of residual conjugate base (e.g., sodium sulfate) (and potentially a small amount of sulfuric acid) is lower than the at least one anode electrolyte inlet stream. In some embodiments, the cathode compartment can be configured to receive at least a portion of the separated cathode electrolyte (e.g., sodium hydroxide) from the gas / liquid separator as the at least one cathode electrolyte inlet stream 11.

[0094] In some embodiments, the system may include at least one dissolution reactor 16. In some embodiments, a feedstock material 17 containing a target element may be dissolved in the at least one dissolution reactor. In some embodiments, the at least one anode electrolyte outlet stream may be mixed with the feedstock material in the at least one dissolution reactor. In some embodiments, the at least one dissolution reactor may be configured to receive the feedstock material and the at least one anode electrolyte outlet stream (i.e., an anode electrolyte product stream). In some embodiments, at least a portion of the feedstock material (e.g., at least the target material) may be dissolved (e.g., dissolved metal (nickel, copper, or a combination thereof)) by the anode electrolyte outlet stream (e.g., bisulfate, acid) in the at least one dissolution reactor. In some embodiments, the acid generated in the anode compartment may be used to dissolve at least a portion of the feedstock material. For example, in some embodiments, the anode electrolyte outlet stream may leach the target element from the feedstock material as a dissolved metal salt (e.g., dissolved sulfate).

[0095] In some embodiments, the dissolved feedstock material, including the dissolved target material (e.g., dissolved metal salts), can be processed by a solvent extractor and / or an electrodepositor 29. In some embodiments, the sulfate salts can be processed by means known in the art, such as solvent extraction (using solvent stream 31) and / or electrodeposition to concentrate the target element (e.g., target metal nickel, copper, or a combination thereof) into target stream 30.

[0096] In some embodiments, the system may include at least one precipitation reactor 19. In some embodiments, the remaining lean solution 32 from which the target material or a majority thereof has been removed may be sent to the at least one precipitation reactor. In some embodiments, the at least one precipitation reactor may precipitate components of the remaining lean solution. In some embodiments, the at least one precipitation reactor may be configured to receive a portion of the separated cathode electrolyte 21 (e.g., sodium hydroxide) and precipitate materials (e.g., hydroxides and / or oxides) from the remaining lean solution. In some embodiments, the at least one precipitation reactor is configured to receive a portion of the separated cathode electrolyte from a gas / liquid separator. In some embodiments, the portion of the separated cathode electrolyte (e.g., sodium hydroxide) from the gas / liquid separator may be mixed with the remaining lean solution to precipitate materials (e.g., hydroxides and / or oxides). As described above, a portion of the separated cathode electrolyte from the gas / liquid separator may be recycled back to the at least one cathode electrolyte inlet stream as the cathode compartment. In some embodiments, the reaction between the separated cathode electrolyte (e.g., sodium hydroxide) and the remaining lean solution (e.g., sulfates of iron, calcium, aluminum, magnesium, etc.) can precipitate materials 33 (e.g., hydroxides and oxides of metals), which in some embodiments can be removed as a slurry. In some embodiments, the overflow of the at least one precipitation reactor (e.g., sodium sulfate) can be sent to the anode compartment to serve as the at least one anode electrolyte inlet stream. In some embodiments, various tailings solids 34 can be recovered from the at least one dissolution reactor, depending on the dissolved salts.

[0097] In some embodiments, the at least one dissolution reactor can be fluidly connected to the anode compartment (or anode electrolyte compartment) and / or the cathode compartment (or cathode electrolyte compartment), the at least one precipitation reactor can be fluidly connected to the anode compartment (or anode electrolyte compartment) and / or the cathode compartment (or cathode electrolyte compartment), the gas / liquid separator can be fluidly connected to the anode compartment (or anode electrolyte compartment or anode-containing compartment) and / or cathode compartment (or cathode electrolyte compartment or cathode-containing compartment), and / or the at least one precipitation reactor can be fluidly connected to the gas / liquid separator. In some embodiments, a solvent extractor and / or an electrodepositor can be fluidly connected to the at least one dissolution reactor and / or the at least one precipitation reactor.

[0098] In some embodiments, the raw material may be a silicon-containing material, such as silicon oxide (eg, silica / silicon dioxide). In some embodiments, the raw material may be silicon dioxide having high crystallinity. Figure 6A-6BA system for performing a silica leaching or silica upgrading process using an electrolyzer disclosed herein according to some embodiments may be illustrated. In some embodiments, Figure 7 An electrolyzer diagram is illustrated, which shows an example reaction that can be used in a silica leaching or silica upgrading process. In some embodiments, the electrolyzer 1 may include an anode (e.g., a porous anode) in an anode-containing compartment 7 of the anode compartment 3. In some embodiments, the anode may be separated from the anode electrolyte compartment 8 (e.g., a flow chamber) via a barrier 6b (e.g., a cation selective membrane). In some embodiments, the anode electrolyte compartment includes an anode electrolyte comprising a weak acid (e.g., acetic acid) and its conjugate base (e.g., sodium acetate). In some embodiments, the anode electrolyte compartment only includes the conjugate base of the weak acid (e.g., sodium acetate). In some embodiments, the anode compartment is separated from the cathode compartment 2 via a barrier 6 (e.g., a cation selective membrane). In some embodiments, the cathode compartment includes a cathode electrolyte comprising an alkali (e.g., ammonium acetate) and a cathode 4. In some embodiments, a power source 14 can drive electrons from the anode to the cathode. In some embodiments, the cathode compartment can support a gas generation reaction (e.g., a hydrogen evolution reaction). In some embodiments, the cathode compartment can be configured to generate a second gas (e.g., ammonia). For example, in some embodiments, at the cathode, base can be released such that aqueous ammonium cations deprotonate and become volatile ammonia, which forms a gas phase along with hydrogen.

[0099] In some embodiments, one or more gases (e.g., hydrogen and / or ammonia) generated by the reaction at the cathode can exit the electrolyzer with at least one cathode electrolyte outlet stream 12 (i.e., cathode electrolyte product stream). In some embodiments, the system can include a gas / liquid separator 15 configured to separate one or more gases from a liquid. In some embodiments, the gas / liquid separator can be configured to receive the at least one cathode electrolyte outlet stream and separate the gas (e.g., hydrogen and / or ammonia) from the reacted cathode electrolyte (e.g., sodium acetate solution). In some embodiments, the anode compartment (e.g., the anode electrolyte compartment) can be configured to receive the separated reacted cathode electrolyte (e.g., sodium acetate) from the gas / liquid separator as the at least one anode electrolyte inlet stream 9.

[0100] In some embodiments, the separated gas 36 from the gas / liquid separator can be sent to the at least one precipitation reactor 19. In some embodiments, the separated gas (e.g., hydrogen and / or ammonia) can enter the precipitation reactor, where it can contact with the dissolved silicon fluoride composite stream 37 (which contains the dissolved silicon fluoride composite). In some embodiments, when contacted with a portion of the separated gas (e.g., ammonia), silica can precipitate and can be removed in the silica product stream (e.g., amorphous silica) 38. In some embodiments, the solution of the precipitator (e.g., NH4HF2) can leave the precipitation reactor as stream 39 with the remaining gas stream 40 (e.g., mainly hydrogen) and be sent to the dissolution reactor 16. In some embodiments, the feed material 17 (e.g., silica with high crystallinity) can be dissolved in the at least one dissolution reactor. In the dissolution reactor, the remaining gas stream 40 (e.g., mainly hydrogen) can strip ammonia from the dissolution reactor, which can help dissolution. The combined gas stream 41 (e.g., hydrogen and ammonia) can leave the dissolution reactor and go to the gas absorber 24 (e.g., a packed bed absorber). In some embodiments, the gas absorber can be configured to receive the combined gas stream and can be configured to remove the target gas (e.g., ammonia) from the combined gas stream. In some embodiments, the gas absorber can capture the gas (e.g., ammonia) in the liquid. In some embodiments, the at least one gas absorber can be configured to receive the anode electrolyte outlet stream (e.g., acetic acid (with some sodium acetate)). In some embodiments, the gas absorber can be configured to capture the target gas in the anode electrolyte outlet stream. In some embodiments, the anode electrolyte outlet stream can be sent to the top of the absorber, where it contacts the combined gas stream (e.g., ammonia and hydrogen) countercurrently. Clean gas or lean gas (e.g., hydrogen) with most of the target gas (e.g., ammonia) removed can leave the absorber. In some embodiments, the anode electrolyte in the absorber can capture the target gas. For example, a loaded ammonium acetate solution can leave the gas absorber to be sent to the cathode compartment (to be the cathode electrolyte inlet stream 11).

[0101] In some embodiments, the clean gas or lean gas can be sent to the anode compartment (e.g., a compartment containing an anode). In some embodiments, the gas can be sent to the anode compartment (if there is no compartment containing an anode, it can be sent to the anode electrolyte compartment) so that it bubbles into the anode compartment. In some embodiments, the clean gas or lean gas (e.g., hydrogen) can be oxidized by the anode to generate hydronium ions and / or protons. In some embodiments, these hydronium ions and / or protons can be transferred through the barrier 6b separating the anode-containing compartment and the anode electrolyte compartment. In some embodiments, the hydronium ions and / or protons can react with the anode electrolyte (e.g., the conjugate base of the anode electrolyte (e.g., sodium acetate)) to form an acid (e.g., acetic acid). In some embodiments, the at least one anode electrolyte outlet flow 10 can include a lower pH than the at least one anode electrolyte inlet flow 9. In some embodiments, the at least one anode electrolyte outlet flow 10 can include a weak acid (e.g., acetic acid), wherein the amount of the residual conjugate base (e.g., sodium acetate) is lower than the at least one anode electrolyte inlet flow.

[0102] In some embodiments, the at least one precipitation reactor may be fluidly connected to the anode compartment (or anode electrolyte compartment) and / or cathode compartment (or cathode electrolyte compartment). In some embodiments, the at least one gas absorber may be fluidly connected to the anode compartment (or compartment containing anode) and / or cathode compartment (or cathode electrolyte compartment). In some embodiments, the gas / liquid separator may be fluidly connected to the cathode compartment (or cathode electrolyte compartment) and / or the precipitation reactor. In some embodiments, the dissolution reactor may be fluidly connected to the precipitation reactor and / or the gas absorber.

[0103] Example

[0104] Figure 8An exemplary device tested in a laboratory environment to simulate the performance of the electrolyzer described in the calcium leaching embodiment is illustrated. The electrolyzer 1 includes a depolarized anode in an anode-containing compartment 7 supplied with hydrogen 13, and the compartment 7 is separated from the anode electrolyte compartment 8 by a cation exchange membrane 6b. The anode electrolyte in the anode electrolyte compartment 8 is a sodium acetate and acetic acid anode electrolyte. The anode electrolyte is also in contact with a cation selective membrane 6. On the opposite side of the membrane is a sodium hydroxide cathode compartment 2, which contains a cathode electrolyte and a cathode that can support HER. The hydrogen generated by the reaction at the cathode can leave the electrolyzer together with the cathode electrolyte outlet stream 12 and enter the gas / liquid separator 15. Hydrogen 13 can leave the gas / liquid separator and be injected into the anode compartment 3 (specifically, the anode-containing compartment 7). The hydrogen can be oxidized at the hydrogen depolarized anode to generate protons, which can react with the sodium acetate in the anode electrolyte to form acetic acid. Therefore, the anode electrolyte leaving the electrolyzer in stream 10 contains acetic acid and sodium acetate and is retained in a reservoir 23. In this electrolyser test rig, the acid can be recycled from the reservoir back to the electrolyser as stream 9, where the sodium acetate can be further converted to acetic acid. The sodium hydroxide stream 11 leaving the gas / liquid separator can be recycled back as the catholyte feed to the electrolyser, where it is further concentrated.

[0105] Fig. 9 Shows Figure 8 The system is at 1kA / m 2 A 10 cm carbon paper anode with a platinum catalyst and a nickel foam cathode was used. 2 Measured pH changes of the catholyte and anolyte over time during operation of the area electrolyzer. The initial solution on both sides of the electrolyzer was 4M sodium acetate and maintained at approximately 77°C. Fig. 9 As can be seen, the pH of the cathode electrolyte increases, indicating the concentration of NaOH, while the pH of the anode electrolyte decreases towards the pKa of acetic acid, indicating the conversion of acetic acid over time. Fig.10 The voltage of the electrolyzer running continuously at 2.2 volts for 33 hours in the test is shown.

[0106] Fig.11An exemplary device tested in a laboratory environment is illustrated to simulate the performance of an electrolyzer described in a carbon dioxide separation embodiment. The electrolyzer 1 includes a depolarized anode in an anode-containing compartment 7 supplied with hydrogen 13, and the compartment 7 is separated from the anode electrolyte compartment 8 by a cation exchange membrane 6b. The anode electrolyte in the anode electrolyte compartment 8 contains potassium carbonate and potassium bicarbonate solutions. The anode electrolyte is also in contact with a cation selective membrane 6. On the opposite side of the membrane is a potassium hydroxide cathode compartment 2, which contains a cathode electrolyte and a cathode that can support HER. The hydrogen generated by the reaction at the cathode can leave the electrolyzer together with the cathode electrolyte outlet stream (exit in stream) 12 and enter the gas / liquid separator 15. Hydrogen 13 can leave the gas / liquid separator and can be injected into the anode compartment 3 (specifically, the anode-containing compartment 7). Hydrogen can be oxidized at the hydrogen depolarized anode to generate protons, which can react with potassium carbonate and potassium bicarbonate in the anode electrolyte to release carbon dioxide and form water, while potassium cations can pass through the cation exchange membrane 6 toward the cathode compartment. Thus, the anolyte exiting the electrolyzer as stream 10 contains gaseous and dissolved carbon dioxide when it enters the gas / liquid separator 15b (e.g., an anolyte flash tank and reservoir). In this electrolyzer test setup, the anolyte can be recycled back to the electrolyzer where additional carbonates and bicarbonates can be converted to carbon dioxide. Potassium hydroxide 11 can exit the gas / liquid separator 15 and can be recycled back as the cathode electrolyte inlet stream 11 of the electrolyzer where it can be further concentrated.

[0107] Fig.12 Shows Fig.11 The system is at 1kA / m 2 A 10 cm carbon paper anode with a platinum catalyst and a nickel foam cathode was used. 2 Measured pH changes of the catholyte and anolyte over time during operation of the area electrolyzer. The initial solution on both sides of the electrolyzer was 1 M sodium sulfate and maintained at approximately 70°C. Fig.12 As can be seen, the pH of the cathode electrolyte increases, indicating the concentration of NaOH, while the pH of the anode electrolyte decreases toward the pKa of sodium bisulfate, indicating the conversion of sulfate to bisulfate over time. Fig.13 The voltage is shown for an electrolyzer operating at approximately 4-5 volts during testing. The voltage can be lowered by using a higher concentration of electrolyte, which will lower the ohmic potential.

[0108] Fig.14An exemplary apparatus tested in a laboratory environment to simulate the performance of the electrolyzer described in the metal leaching embodiment is illustrated. The electrolyzer 1 includes a depolarized anode in an anode-containing compartment 7 supplied with hydrogen 13, and the compartment 7 is separated from the anode electrolyte compartment 8 by a cation exchange membrane 6b. The anode electrolyte in the anode electrolyte compartment 8 contains sodium sulfate and sodium bisulfate. The anode electrolyte is also in contact with the cation selective membrane 6. On the opposite side of the membrane is a potassium hydroxide cathode compartment 2, which contains a cathode electrolyte and a cathode that can support HER. The hydrogen generated by the reaction at the cathode can leave the electrolyzer together with the cathode electrolyte outlet stream 12 and enter the gas / liquid separator 15. Hydrogen 13 can leave the gas / liquid separator and can be injected into the anode compartment 3 (specifically, the anode-containing compartment 7). The hydrogen can be oxidized at the hydrogen depolarized anode to generate protons, which can react with the sodium sulfate in the anode electrolyte to form sodium bisulfate. Thus, the anolyte exiting the electrolyzer as stream 10 contains sodium bisulfate and sodium sulfate and is sent to the anolyte reservoir 35. In this electrolyzer test setup, the anolyte can be recycled from the reservoir back to the electrolyzer where the additional sodium sulfate can be converted to sodium bisulfate. Sodium hydroxide can exit the gas / liquid separator 15 and be recycled back as the catholyte inlet stream 11 of the electrolyzer where it can be further concentrated.

[0109] Fig.15 Shows Fig.14 The system should be at 0.2kA / m 2 A 10 cm carbon paper anode with a platinum catalyst and a nickel foam cathode was used. 2 Figure 3. Evolution of CO2 over time during operation of an area electrolyzer. The cathode electrolyte used in this experiment was 2M potassium hydroxide and the anode electrolyte was 1M potassium bicarbonate. The tests were performed at 25°C to highlight the generation of carbon dioxide electrochemically rather than from the thermal decomposition of bicarbonate. Fig.15 As can be seen in Figure 5, the current induced the release of about 3.6 mL / min of CO2 from the bicarbonate solution, which is consistent with the conversion of one electron to one proton to decompose one molecule of CO2. Fig.16 The voltage of an electrolyzer operating during testing at approximately 3-4 volts is shown. Lower voltages may be achieved by operating at higher temperatures and using a more concentrated electrolyte.

[0110] List of implementation plans

[0111] The following examples represent some aspects of the present disclosure:

[0112] Embodiment 1: A method for conducting a chemical or biological reaction affected by pH, comprising: an electrolyzer comprising an anode compartment and a cathode compartment; an anode in the anode compartment where an oxidation reaction occurs; a cathode in the cathode compartment where a reduction reaction occurs; a cathode electrolyte solution in direct contact with the cathode or through an ion conductive barrier, the cathode electrolyte solution leaving the cathode compartment at a higher pH than when it entered the cathode compartment; an anolyte solution in direct contact with the anode or through an ion conductive barrier, the anolyte solution leaving the anode compartment at a lower pH than when it entered the anode compartment; an ion conductive barrier separating the anode compartment from the cathode compartment; dissolved components in the anode electrolyte, the cathode electrolyte, or both, which act as a pH buffer; a gas evolved from one electrode which is consumed at the other electrode; a second ion conductive barrier separating the electrode consuming the gas from a liquid anode electrolyte or cathode electrolyte; using an anode electrolyte or cathode electrolyte flow to conduct a pH-affected reaction; and combining portions of the anode electrolyte flow and the cathode electrolyte flow into a neutralized flow and then feeding the neutralized flow back to the electrolyzer.

[0113] Embodiment 2: The method of Embodiment 1, wherein the anode electrolyte comprises an organic acid.

[0114] Embodiment 3: The method of Embodiment 1, wherein the anode electrolyte comprises an inorganic acid.

[0115] Embodiment 4: The method of Embodiment 1, wherein acetate is converted to acetic acid in the anode compartment.

[0116] Embodiment 5: The method of Embodiment 1, wherein the carbonate is acidified resulting in the release of carbon dioxide.

[0117] Embodiment 6: The method of Embodiment 1, wherein hydrogen is evolved at the cathode and consumed in the anode.

[0118] Embodiment 7: The method of Embodiment 1, wherein oxygen is evolved at the anode and consumed at the cathode.

[0119] Embodiment 8: The method of Embodiment 1, wherein the cathode electrolyte comprises ammonia and / or ammonium.

[0120] Embodiment 9: The method of Embodiment 1, wherein the cathode electrolyte comprises an amine.

[0121] Embodiment 10: The method of Embodiment 1, wherein the cathode electrolyte comprises an organic base.

[0122] Embodiment 11: The method of Embodiment 1, wherein the cathode electrolyte comprises an inorganic base.

[0123] Embodiment 12: The method of Embodiment 1, wherein the anolyte exiting the anode compartment is used to extract acid or base soluble species.

[0124] Embodiment 13: A method for capturing and concentrating acidic gases, comprising: an electrolyzer, the electrolyzer comprising an anode compartment and a cathode compartment; an anode in the anode compartment, where an oxidation reaction occurs; a cathode in the cathode compartment, where a reduction reaction occurs; a cathode electrolyte solution directly in contact with the cathode or through an ion conductive barrier, the cathode electrolyte solution leaving the cathode compartment at a pH greater than 7; an anode electrolyte solution directly in contact with the anode or through an ion conductive barrier, the anode electrolyte solution leaving the anode at a pH less than 6; a cation exchange membrane separating the anode compartment from the cathode compartment; acidic gases being evolved in the anode electrolyte compartment; hydrogen evolved from the cathode being consumed at the anode; a cation exchange membrane separating the hydrogen and the anode from the anode electrolyte; a cathode electrolyte that captures and absorbs acidic gases; and using an acidic gas-rich cathode electrolyte as an anode electrolyte feed for the electrolyzer.

[0125] Embodiment 14: The method of Embodiment 13, wherein the carbon capture system is used to capture CO2 directly from air.

[0126] Embodiment 15: The method of Embodiment 14, wherein the cathode electrolyte comprises a hydroxide at a concentration of 1 mol / L or greater.

[0127] Embodiment 16: The method of Embodiment 13, wherein the carbon capture system is used to capture CO2 from a stream having a carbon dioxide content greater than 1% by volume.

[0128] Embodiment 17: The method of Embodiment 16, wherein the cathode electrolyte comprises a carbonate or an amine or a combination thereof.

[0129] Embodiment 18: A method for extracting valuable components from a raw material, comprising: an electrolyzer, the electrolyzer comprising an anode compartment and a cathode compartment; an anode in the anode compartment, where an oxidation reaction occurs; a cathode in the cathode compartment, where a reduction reaction occurs; a cathode electrolyte solution directly in contact with the cathode or through an ion conductive barrier, the cathode electrolyte solution leaving the cathode compartment at a pH greater than 7; an anode electrolyte solution directly in contact with the anode or through an ion conductive barrier, the anode electrolyte solution leaving the anode at a pH less than 6; a cation exchange membrane separating the anode compartment from the cathode compartment; hydrogen evolved from the cathode is consumed at the anode; a cation exchange membrane separating the hydrogen and the anode from the anode electrolyte; using the cathode electrolyte or the anode electrolyte as a leaching solution and placing it in contact with a raw material having a first concentration of a target element; extracting a portion of the target element into the leaching solution; separating the leaching solution from the residue of the raw material; recovering the target element from the leaching solution; and recycling the leaching solution to the electrolyzer.

[0130] Embodiment 19: The method of Embodiment 18, wherein an anode electrolyte is used as the leaching solution and comprises an organic acid.

[0131] Embodiment 20: The method of Embodiment 18, wherein the anode electrolyte is used as the leaching solution and comprises a mineral acid.

[0132] Embodiment 21: The method of Embodiment 19, wherein the organic acid comprises acetic acid.

[0133] Embodiment 22: The method of Embodiment 20, wherein the inorganic acid comprises a bisulfate salt.

[0134] Embodiment 23: The method of Embodiment 18, wherein the leach solution is an anolyte, the target element is magnesium or calcium, and is recovered by precipitation as a hydroxide by adding a catholyte to the leach solution.

[0135] Embodiment 24: The method of Embodiment 18, wherein the leaching solution is an anolyte and the target element is a transition metal such as nickel, copper, cobalt, chromium or manganese and is recovered by electrowinning.

[0136] Embodiment 25: The method of Embodiment 18, wherein the leaching solution is a cathode electrolyte and comprises potassium hydroxide or sodium hydroxide.

[0137] Embodiment 26: The method of Embodiment 25, wherein the target element is aluminum.

[0138] Embodiment 27: The method of Embodiment 25, wherein the target element is a platinum group metal or a rare earth metal.

[0139] Embodiment 28: The method of Embodiment 18, wherein the anode electrolyte exiting the anode compartment is used to dissolve slag generated by a furnace or boiler.

[0140] Embodiment 29: The method of Embodiment 18, wherein the anode electrolyte exiting the anode compartment is used to dissolve ash generated by a furnace or boiler.

[0141] Embodiment 30: The method of Embodiment 18, wherein the anode electrolyte exiting the anode compartment is used to dissolve naturally occurring rock or stone.

[0142] Embodiment 31: The method of Embodiment 18, wherein the anode electrolyte exiting the anode compartment is used to dissolve a material containing a metal salt, and the cathode electrolyte exiting the cathode compartment is used to precipitate the dissolved material into one or more metal hydroxides or metal oxides.

[0143] Embodiment 32: The method of Embodiment 31, which is used to produce calcium hydroxide from calcium-containing materials.

[0144] Embodiment 33: The method of Embodiment 32, wherein the calcium hydroxide is produced for use in making a cementitious product.

[0145] Embodiment 34: The method of Embodiment 13, which is used to separate acid gases.

[0146] Embodiment 35: The method of Embodiment 13, which is used to separate sulfur oxide gases.

[0147] Embodiment 36: The method of Embodiment 13 is used to separate nitrogen oxide gas.

[0148] Embodiment 37: The method of Embodiment 13, which is used to separate reduced sulfur gases including hydrogen sulfide.

[0149] Embodiment 38: A method for capturing and concentrating alkaline gases, comprising: an electrolyzer, the electrolyzer comprising an anode compartment and a cathode compartment; an anode in the anode compartment, where an oxidation reaction occurs; a cathode in the cathode compartment, where a reduction reaction occurs; a cathode electrolyte solution directly in contact with the cathode or through an ion conductive barrier, the cathode electrolyte solution leaving the cathode compartment at a pH greater than 7; an anode electrolyte solution directly in contact with the anode or through an ion conductive barrier, the anode electrolyte solution leaving the anode at a pH less than 6; an ion conductive barrier separating the anode compartment from the cathode compartment; precipitating alkaline gases in the cathode electrolyte compartment; hydrogen gas precipitated from the cathode being consumed at the anode; a cation exchange membrane separating the hydrogen and the anode from the anode electrolyte; using the anode electrolyte to capture and absorb acidic gases; using an anode electrolyte rich in alkaline gases as a cathode electrolyte feed for the electrolyzer.

[0150] Embodiment 39: The method of Embodiment 38, which is used to separate alkaline gases.

[0151] Embodiment 40: The method of Embodiment 38, which is used to separate and / or concentrate ammonia.

[0152] Embodiment 41: The method of Embodiment 40 for dissolving and precipitating silica.

[0153] Embodiment 42: The method of Embodiment 40 for dissolving and precipitating alumina.

[0154] Embodiment 43: The method of Embodiment 40 for dissolving and precipitating aluminosilicates.

[0155] Embodiment 44: The method of Embodiment 1, wherein chlorine is evolved at the anode and consumed at the cathode.

[0156] Embodiment 45: A method comprising operating a system and / or an apparatus according to any one of Embodiments 1-44.

[0157] Embodiment 46: A system and / or apparatus configured to perform the operations of the method of any one of Embodiments 1-44.

[0158] Additional Definitions

[0159] Unless otherwise defined, all technical terms, symbols and other technical and scientific terms or nouns used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which the claimed subject matter belongs. In some cases, terms with commonly understood meanings are defined herein for clarity and / or for ease of reference, and the inclusion of such definitions herein should not necessarily be construed as indicating a substantial difference from what is generally understood in the art.

[0160] Reference herein to "about" a certain value or parameter includes (and describes) changes to the value or parameter itself. For example, a description referring to "about X" includes a description of "X". In addition, reference to a string of values ​​or parameters followed by a statement "less than", "greater than", "at most", "at least", "less than or equal to", "greater than or equal to" or other similar statements is intended to apply the statement to each value or parameter in the string of values ​​or parameters. For example, a statement that a weak acid can exist in the form of its conjugate base less than about 100%, about 90% or about 80% is intended to indicate that a weak acid can exist in the form of its conjugate base less than about 100%, less than about 90% or less than about 80%.

[0161] The present application discloses several numerical ranges in the text and drawings. The disclosed numerical ranges inherently support any range or value within the disclosed numerical ranges, including endpoints, even if the specification does not verbatim state the precise range limitations, because the present disclosure can be implemented within the entire disclosed numerical range.

[0162] As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that, as used herein, the term "and / or" refers to and encompasses any and all possible combinations of one or more of the associated listed items. It should also be understood that when used herein, the terms "includes", "including", "comprises", and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, components, and / or units, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0163] The scope of the present disclosure covers all changes, substitutions, variations, alterations and modifications to the example embodiments described or illustrated herein that will be understood by those of ordinary skill in the art. The scope of the present disclosure is not limited to the example embodiments described or illustrated herein. In addition, it will be understood by those of ordinary skill in the art that although the present disclosure describes and illustrates the various embodiments herein as including specific parts, elements, features, functions, operations or steps, any of these embodiments may include any combination or arrangement of any parts, elements, features, functions, operations or steps described or illustrated anywhere herein. In addition, the references to devices or systems or parts of devices or systems suitable for, arranged to, capable of, configured to, enabled to, operable to or operated to perform specific functions in the appended claims include the device, system, component, whether it or the specific function is activated, switched on or unlocked, as long as the device, system or component is so suitable, arranged, capable, configured, enabled, operable or operated. In addition, although the present disclosure describes or illustrates specific embodiments as providing specific advantages, specific embodiments may not provide any of these advantages, provide some of these advantages or provide all of these advantages.

Claims

1. A method, comprising: generating hydrogen gas in a cathode compartment of an electrolyzer, wherein the cathode compartment comprises a cathode electrolyte and a cathode; delivering the hydrogen gas to an anode-containing compartment of the electrolyzer, wherein the anode-containing compartment comprises an anode and is separated from an anode electrolyte compartment comprising a pH buffer by a first ion-selective barrier, and the anode electrolyte compartment is separated from the cathode compartment by a second ion-selective barrier; oxidizing the hydrogen gas in the anode-containing compartment to generate protons; as well as Acid is generated in the anode electrolyte compartment using the protons received through the ion selective barrier.

2. The method of claim 1, wherein the open circuit potential of the electrolyzer is less than 1 volt.

3. The method of any one of claims 1-2, wherein the pH buffer comprises a weak acid and its conjugate base.

4. The method of claim 3, wherein the weak acid comprises acetic acid, bicarbonate, or bisulfate, and the conjugate base comprises acetate, carbonate, or sulfate.

5. The method according to any one of claims 1 to 4, further comprising dissolving a feedstock material containing a target element with the acid, and precipitating and / or electrodepositing the target element from the dissolved feedstock material.

6. The method of claim 5, wherein precipitating and / or electrodepositing the target element from the dissolved feedstock material uses the cathode electrolyte.

7. The method of any one of claims 1-6, further comprising separating the hydrogen from the cathode electrolyte.

8. The method of any one of claims 1-7, further comprising capturing acid gases from a gas mixture with the cathode electrolyte and delivering the cathode electrolyte with the captured acid gases to the anode electrolyte compartment.

9. The method of any one of claims 1-8, further comprising generating an acid gas in the anode electrolyte compartment.

10. The method of claim 9, further comprising separating the acid gas from the anode electrolyte.

11. A system, comprising: An electrolyzer, the electrolyzer comprising: a cathode compartment comprising a cathode electrolyte and a cathode; and an anode compartment comprising an anode electrolyte compartment comprising a pH buffer and an anode-containing compartment comprising an anode, in: The cathode compartment is separated from the anode compartment by a first ion selective barrier, and the anolyte compartment is separated from the anode-containing compartment by a second ion selective barrier; The cathode compartment is configured to generate hydrogen; The anode-containing compartment is configured to receive the hydrogen gas and oxidize the hydrogen gas to generate protons; and The anode electrolyte compartment is configured to receive the protons that pass through the second ion selective barrier and generate an acid.

12. The system of claim 11, further comprising a dissolution reactor configured to receive the acid from the anode electrolyte compartment and dissolve a feedstock material comprising a target element.

13. The system of claim 12, further comprising a precipitation reactor configured to receive dissolved feedstock material and precipitate the target element from the dissolved feedstock material.

14. The system according to any one of claims 11-13, further comprising a gas / liquid separator, which is configured to receive a cathode electrolyte outlet flow from the cathode compartment and separate the cathode electrolyte outlet flow into hydrogen gas and the cathode electrolyte.

15. The system of claim 14, wherein hydrogen from the gas / liquid separator is sent to the anode-containing compartment.

16. The system of any one of claims 14-15, wherein at least a portion of the cathode electrolyte from the gas / liquid separator is sent to the cathode compartment.

17. The system of any one of claims 14-16, wherein at least a portion of the cathode electrolyte from the gas / liquid separator is sent to a precipitation reactor to precipitate a target element from dissolved feedstock material.

18. The system of any one of claims 14-17, further comprising an absorber configured to receive a portion of the cathode electrolyte from the gas / liquid separator, receive a gas mixture comprising an acidic gas, and capture the acidic gas in the cathode electrolyte.

19. The system of claim 18, wherein the cathode electrolyte with captured acid gas is delivered to the anode electrolyte compartment.

20. The system of any one of claims 11-19, wherein the anode electrolyte compartment is configured to generate acid gas.

21. The system of claim 20, further comprising a second gas / liquid separator configured to receive an anolyte product and separate the anolyte product into an acid gas and the anolyte.

22. The system of claim 21, wherein at least a portion of the anode electrolyte from the second gas / liquid separator is sent to the anode electrolyte compartment.

23. The system of any one of claims 11-22, wherein the electrolyzer has an open circuit potential of less than 1 volt.

24. The system of any one of claims 11-13, wherein the pH buffer comprises a weak acid and its conjugate base.

25. The system of claim 24, wherein the weak acid comprises acetic acid, bicarbonate, or bisulfate, and the conjugate base comprises acetate, carbonate, or sulfate.

26. An electrolyzer, comprising: a cathode compartment comprising a cathode electrolyte and a cathode; as well as an anode compartment comprising an anode electrolyte compartment comprising a pH buffer and an anode-containing compartment comprising an anode, in: The cathode compartment is separated from the anode compartment by a first ion selective barrier, and the anolyte compartment is separated from the anode-containing compartment by a second ion selective barrier; The cathode compartment is configured to generate hydrogen; The anode-containing compartment is configured to receive the hydrogen gas and oxidize the hydrogen gas to generate protons; and The anode electrolyte compartment is configured to receive the protons that pass through the second ion selective barrier and generate an acid.

27. The electrolyzer of claim 26, wherein the electrolyzer has an open circuit potential of less than 1 volt.

28. The electrolyser of any one of claims 26-27, wherein the pH buffer comprises a weak acid and its conjugate base.

29. The electrolyzer of claim 28, wherein the weak acid comprises acetic acid, bicarbonate, or bisulfate, and the conjugate base comprises acetate, carbonate, or sulfate.

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