High flow rate cell design for the electrochemical production of hydrogen and carbon dioxide.

Abstract

An apparatus for producing carbon dioxide and hydrogen from water having carbonate species is disclosed. The apparatus includes an anode compartment having an anode disposed on a first side of the anode compartment, and a cathode compartment having a cathode disposed on a first side of the cathode compartment. The apparatus further includes a first cation permeable fluid separator disposed on a second side of the anode compartment, and a second cation permeable fluid separator disposed on a second side of the cation compartment. A central compartment is defined between the first cation permeable fluid separator and the second cation permeable fluid separator. The apparatus further includes a flow control system configured to independently control the flow of water through each of the anode compartment, the cathode compartment, and the central compartment. A method for producing hydrogen, carbon dioxide, and oxygen from seawater using the apparatus is also disclosed.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 63 / 186,905, entitled "HIGH FLUID VELOCITY CELL DESIGN FOR THE ELECTROCHEMICAL GENERATION OF HYDROGEN AND CARBON DIOXIDE," filed May 11, 2021, and U.S. Provisional Application No. 63 / 187,519, entitled "METHOD OF OPERATING ELECTROCHEMICAL HYDROGEN AND CARBON DIOXIDE GENERATOR," filed May 12, 2021, each of which is incorporated by reference in its entirety for all purposes.

[0002] Aspects and embodiments disclosed herein provide a method for the production of seawater by acidifying seawater to produce carbon dioxide (CO 2 ) and hydrogen (H 2 The present invention relates to an apparatus and method for generating and capturing Summary of the Invention

[0003] According to one aspect, an apparatus for producing carbon dioxide and hydrogen from water having carbonate species is provided. The apparatus may include an anode compartment having an anode disposed on a first side of the anode compartment and a cathode compartment having a cathode disposed on a first side of the cathode compartment. The apparatus may include a first cation permeable fluid separator disposed on a second side of the anode compartment. The apparatus may further include a second cation permeable fluid separator disposed on the second side of the cathode compartment. The apparatus may further include a central compartment defined between the first cation permeable fluid separator and the second cation permeable fluid separator. The apparatus may further include a flow control system configured to independently control the flow of water through each of the anode compartment, the cathode compartment, and the central compartment.

[0004] In further embodiments, the apparatus may include a water source, e.g., seawater, fluidly connectable to each of the anode compartment, the cathode compartment, and the central compartment.

[0005] In further embodiments, the apparatus may include a pH sensor disposed downstream of the central compartment and configured to measure the pH of the effluent from the central compartment. In certain embodiments, the apparatus may include a controller configured to receive a measurement of the pH of the effluent from the central compartment from the pH sensor and adjust one or both of the flow rate of water through the central compartment or the current applied across the anode and cathode to maintain the pH of the effluent from the central compartment at a predetermined level. The predetermined level may be when a majority of the carbonate species in the effluent from the central compartment is carbonate, i.e., H. 2 CO 3 This is the level at which it exists.

[0006] In some embodiments, the controller can be configured to maintain the pH of the effluent from the central compartment within a range of about 2.5 to about 6.5.

[0007] In a further embodiment, the apparatus may further include a conductivity sensor constructed and arranged to measure the conductivity of one or more effluents from the anode, the cathode, and the central compartment. In a further embodiment, the controller may be configured to adjust the flow rate of water through the cathode compartment in response to the conductivity measurements from the conductivity sensor. In a further embodiment, the controller may be configured to adjust the flow rate of effluent from the anode compartment to the cathode compartment in response to the conductivity measurements from the conductivity sensor. In a further embodiment, the controller may be configured to adjust the flow rate of water through the cathode compartment to a flow rate that does not result in the formation of scale on the cathode. In a further embodiment, the controller may be configured to adjust the flow rate of water through the anode compartment in response to the conductivity measurements from the conductivity sensor. In a further embodiment, the controller may be configured to minimize the flow rate of water through the anode compartment to a flow rate that does not result in blinding of the anode.

[0008] In a further embodiment, the apparatus may include a recirculation line configured to recirculate at least a portion of the effluent from the anode compartment to the inlet of the anode compartment.

[0009] In further embodiments, the apparatus may include a recirculation line configured to recirculate at least a portion of the effluent from the cathode compartment to the inlet of the cathode compartment. In further embodiments, the apparatus may include a second recirculation line configured to recirculate at least a portion of the effluent from the anode compartment to the inlet of the cathode compartment.

[0010] In further embodiments, the apparatus may include a recirculation line configured to recirculate at least a portion of the effluent from the central compartment to an inlet of the central compartment. In further embodiments, the apparatus may include a recirculation line configured to recirculate at least a portion of the effluent from the central compartment to an inlet of one or both of the anode and cathode compartments.

[0011] In further embodiments, the apparatus may include a gas recovery system configured to remove one or more of hydrogen, carbon dioxide, or oxygen from one or more of the effluents from one or more of the anode compartment, the cathode compartment, or the central compartment. In some embodiments, the gas recovery system may include one or more vacuum strippers.

[0012] In some embodiments, the anode comprises an oxygen evolving coating comprising one of iridium oxide or Magneli phase titanium suboxide, hi some embodiments, the anode may comprise stainless steel, iridium-cobalt (Ir-Co), iridium-tantalum (Ir-Ta), or an alloy comprising one of the other iridium or tantalum species.

[0013] According to one aspect, a method of producing hydrogen, carbon dioxide, and oxygen from seawater is provided. The method may include introducing seawater into each of an anode compartment, a cathode compartment, and a central compartment of an electrolysis cell. The method may include maintaining one or both of a flow rate through the central compartment or a current across the anode and cathode at a level that results in an effluent from the central compartment exhibiting a pH within a predetermined range. The method may further include maintaining a flow rate through the cathode compartment at a level that mitigates formation of scale on the cathode. The method may further include maintaining a flow rate through the anode compartment at a level that mitigates clogging of the anode. The method may further include removing one or more of hydrogen, carbon dioxide, or oxygen from the respective effluents from one or more of the anode compartment, the central compartment, or the cathode compartment. The electrolysis cell may include an anode, a cathode, a first cation permeable fluid separator spaced apart from the anode and defining an anode compartment, a second cation permeable fluid separator spaced apart from the cathode and defining a cathode compartment, a central compartment defined between the first and second cation permeable fluid separators, and a flow control system configured to independently control a flow of seawater through each of the anode compartment, the cathode compartment, and the central compartment.

[0014] In a further embodiment, the method may include maintaining a flow rate through the cathode compartment at a minimum level that mitigates the formation of scale on the cathode.

[0015] In a further embodiment, the method may include maintaining the flow rate through the anode compartment at a minimum level that mitigates clogging of the anode.

[0016] In a further embodiment, the method may include introducing a portion of the effluent from the anode compartment into the inlet of the anode compartment along with the seawater introduced into the anode compartment.

[0017] In a further embodiment, the method may include introducing a portion of the effluent from the anode compartment into the inlet of the cathode compartment along with the seawater introduced into the anode compartment.

[0018] In a further embodiment, the method may include introducing a portion of the effluent from the central compartment into an inlet of the central compartment along with the seawater introduced into the central compartment.

[0019] In further embodiments, the method may include maintaining a flow rate through at least one of the anode compartment, the cathode compartment, or the central compartment at a different level than another of the at least one of the anode compartment, the cathode compartment, or the central compartment.

[0020] In a further embodiment, the method may include maintaining a flow rate through the cathode compartment at a higher flow rate than the flow rate through the central compartment. [Brief description of the drawings]

[0021] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like reference numeral. For purposes of clarity, not every component is labeled in every drawing. [Figure 1] FIG. 1 illustrates an existing electrochemical cell containing ion exchange media for producing carbon dioxide and hydrogen from water having carbonate species. [Diagram 2] FIG. 1 illustrates an apparatus for producing carbon dioxide and hydrogen from water having carbonate species, according to one embodiment. [Diagram 3] FIG. 1 illustrates an apparatus for producing carbon dioxide and hydrogen from water having carbonate species according to an alternative embodiment. [Figure 4A] 4A-4C illustrate anode and cathode configurations for devices according to different embodiments, with FIG. 4A showing a parallel plate arrangement. [Figure 4B]4A-4C illustrate anode and cathode configurations for devices according to different embodiments, with FIG. 4B showing a concentric tube arrangement. [Figure 4C] 4A-4C illustrate anode and cathode configurations for devices according to different embodiments, with FIG. 4C showing a spirally wound configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The total carbon content of the world's oceans is about 38,000 gigatons (GT). More than 95% of this carbon is in the form of dissolved bicarbonate ions (HCO 3 - ) This bicarbonate ion is in the form of carbonate ion (CO 3 2- ), they act to buffer (neutralize) and maintain the ocean's pH, which remains relatively constant within the first 100 meters of ocean depth. Dissolved bicarbonate and carbonate ions present in the ocean effectively bind CO 2 and the sum of the concentrations of these species is dissolved gaseous CO 2 The total carbon dioxide concentration in seawater [CO 2 ] T Represents.

[0023] At a typical ocean pH of 7.8, which is kept relatively constant by a complex bicarbonate-carbonate buffer system, [CO 2 ] T is about 2000 μmol / kg near the surface and about 2400 μmol / kg at depths of less than 300 meters. This is a [CO 2 ] T equivalent to the total CO in the ocean. 2 Of this, approximately 2-3% is dissolved gaseous CO 2 Approximately 1% exists as dissolved carbonate ions, and the remaining 96% exists as dissolved bicarbonate ions. 2 It is known that the equilibrium state and concentration of water containing various ionic forms of H and H+ depend on the pH of the water. For example, at pH 4.5 in seawater, 99% of all carbonate species in seawater are carbonic acid, H 2 CO 3Therefore, HCO 3 - H 2 CO 3 The pH of seawater can be lowered to convert it to

[0024] Dissolved CO in water 2 is expressed as H 2 CO 3 is in equilibrium with CO 2 +H 2 O ⇔ H 2 CO 3 (1)

[0025] The hydration equilibrium constant is 1.70 × 10 -3 This is H 2 CO 3 is not stable in water and gaseous CO 2 dissociates readily at pH 4.5, which causes seawater to become acidic, resulting in CO 2 is easily removed by degassing or stripping, and the unstable H 2 CO 3 is deprotonated to the predominant carbonate species.

[0026] Electrochemical cells are used in marine, offshore, municipal, industrial, and commercial applications. Electrochemical cell design parameters, such as electrode spacing, electrode thickness and coating density, electrode area, method of electrical connection, etc., can be selected for different implementations. The aspects and embodiments disclosed herein are not limited to the number of electrodes, the spacing between electrodes, the electrode material, the material of any spacers between the electrodes, the number of passes in the electrochemical cell, or the electrode coating material.

[0027] Electrochemical cells containing ion exchange media within compartments enclosed by membranes have been used to produce carbon dioxide and hydrogen from water with carbonate species, such as the existing electrochemical cell shown in FIG. 1. In operation, when an electric current is applied, sodium ions present in the water are exchanged for hydrogen ions as the water passes through two cation exchange membranes that form compartments containing cation (positive ion) exchange resin. At the cathode side of the electrochemical cell, sodium hydroxide and hydrogen gas are produced, and at the anode side, oxygen gas is produced. The hydrogen ions enter the central compartment of the electrochemical cell, which contains an inert medium, e.g., ceramic particles, improving the ion transfer efficiency of the cation exchange membranes and causing the acidification of seawater.

[0028] Although the present disclosure describes various embodiments of electrochemical cells and electrochemical devices, the disclosure is not limited to electrochemical cells or devices, and the aspects and embodiments disclosed herein are applicable to electrolysis cells and electrochemical cells used for any one of a number of purposes.

[0029] In certain non-limiting embodiments, the present disclosure describes an electrochemical cell for continuous acidification of water having carbonate species and recovery of dissolved carbon dioxide with continuous hydrogen gas production. The influent to the electrochemical cell is water having carbonate species, e.g., salt water, e.g., seawater, brackish water, or process water, without the need for upstream treatment to reduce the concentration of species such as salts in the water prior to acidification. As used herein, "saline" is water containing a high concentration of dissolved solids or salts, e.g., a concentration of dissolved salts of about 500 ppm to about 35,000 ppm. The electrochemical cell described in the present disclosure includes an anode compartment having an anode disposed on a first side of the anode compartment and a cathode compartment having a cathode disposed on a first side of the cathode compartment. The anode compartment and the cathode compartment contain no electrolyte or medium, allowing for a higher flow of water having carbonate species through the compartment. The higher flow rate of water having carbonate species through the compartment reduces the possibility of scale formation on structural elements of the compartment, such as the anode and cathode. As used herein, flow rate is a measure of how fast water directed to the inlet of one or more compartments travels, measured as a distance per unit time. Flow rate is a measure of the amount of water delivered per unit time. The flow rate of water containing carbonate species is generally determined by the distribution of ions across the permeable separator, i.e., the acidification of the water and the removal of O from the device. 2 , H 2 , and CO 2 Generally, other variables that can be measured or quantified, such as flow rate, aspect ratios of the various equipment components, and friction coefficients between the water being treated and the various equipment components, affect the rate at which water flows through the sections of the equipment.

[0030] The electrochemical cell includes a first cation permeable fluid separator disposed on the second side of the anode compartment and a second cation permeable fluid separator disposed on the second side of the cathode compartment. A central compartment is defined between the first cation permeable fluid separator and the second cation permeable fluid separator. The central compartment may be free of media. The electrochemical cell may be part of an apparatus that includes a flow control system constructed and arranged to independently control the flow of water having carbonate species through each of the anode compartment, the cathode compartment, and the central compartment.

[0031] During operation, a current applied to the device with water having carbonate species as the influent produces hydrogen gas (H 2 ) in the anode compartment via water splitting without the need for any medium, such as an ion exchange resin, present in either compartment. + ) is generated. H + The ions pass through the first cation permeable fluid separator into the central compartment, lowering the pH of the water having carbonate species flowing therethrough. The central compartment does not require the use of an inert medium, such as ceramic particles, to enhance the ion transport capacity or performance of the first cation permeable fluid separator or the second cation permeable fluid separator, since the flow rate of the water having carbonate species through the device is sufficient to reduce scaling and performance degradation. This reduction in pH of the water having carbonate species causes the carbonate (CO2) present in the water having carbonate species to dissolve, as dictated by the equilibrium defined in equation (1). 3 2- ) and bicarbonate (HCO 3 - ) ions of carbon dioxide (CO 2 ) gas. It reduces the pH of water containing carbonate species and also increases the amount of CO 2 No additional electrical current or power or ion exchange media is required to generate the

[0032] The reactions occurring in the anode compartment, cathode compartment, and center compartment include equations (2)-(4), respectively: 2H2 O → 4H + +O 2 +4e￣ (2) 4H 2 O+4Na + +4e￣ → 4NaOH+2H 2 (3) 4NaHCO 3 +4H + → 4Na + +4H 2 CO 3 (4) Therefore, the overall reaction (equation 5) for the device is: 2H 2 O+4NaHCO 3 → 4CO 2 +4NaOH+8H 2 +O 2 (5) It becomes. Where CO 2 is formed in the central compartment according to the equilibrium in equation (1), and NaOH and H 2 is formed in the cathode compartment, and O 2 is formed in the anode compartment. These reaction products can be captured or otherwise collected and used as feedstock for related processes such as energy production, organic synthesis, and water oxygenation (e.g., for aquaculture applications).

[0033] One embodiment of an apparatus for producing carbon dioxide and hydrogen from water with a carbonate species source is shown in Figure 2. In Figure 2, the apparatus 100 includes an anode compartment 102 having an anode 102a disposed on a first side of the anode compartment 102 and a cathode compartment 104 having a cathode 104a disposed on a first side of the cathode compartment. A first cation permeable fluid separator 106 is disposed on a second side of the anode compartment 102 and a second cation permeable fluid separator 108 is disposed on a second side of the cathode compartment 104. The apparatus 100 includes a central compartment 110 defined between the first cation permeable fluid separator 106 and the second cation permeable fluid separator 108.

[0034] Anodes and cathodes, as used herein, are generally understood to refer to electrodes formed from, including, or consisting of one or more metals, such as titanium, aluminum, nickel, other metals, or alloys thereof. In some embodiments, the anode and / or cathode may include multiple layers of different metals. Metal electrodes utilized in any one or more of the embodiments disclosed herein may include a core of highly conductive metal, such as copper or aluminum, coated with a metal or metal oxide that is highly resistant to chemical attack by water having carbonate species, such as titanium, platinum, mixed metal oxides (MMOs), magnetite phase titanium (e.g., Ti 4 O 7 The anode or cathode may include, for example, but not limited to, an oxidation resistant coating such as platinum, MMO, magnetite, ferrite, cobalt spinel, tantalum, palladium, iridium, silver, gold, or other coating material. The mixed metal oxides utilized in the embodiments disclosed herein may include one or more oxides of ruthenium, rhodium, tantalum (optionally alloyed with antimony and / or manganese), titanium, iridium, zinc, tin, antimony, titanium-nickel alloy, titanium-copper alloy, titanium-iron alloy, titanium-cobalt alloy, or other suitable metal or alloy.

[0035] The anodes utilized in the embodiments disclosed herein may be coated with one or more oxides of platinum and / or iridium, ruthenium, tin, rhodium, or tantalum, optionally alloyed with antimony and / or manganese. The cathodes utilized in the embodiments disclosed herein may be coated with platinum and / or iridium (e.g., IrO 2 ), ruthenium, and titanium, such as Magneli phase titanium (e.g., Ti 4 O 7) may be coated with an oxide of one or more of the following: titanium, tantalum, zirconium, niobium, tungsten, and / or silicon. The electrodes of any of the electrochemical cells in the devices disclosed herein may be formed as or from plates, sheets, foils, extrudates, and / or sinters. The anodes and cathodes may be solid electrodes, mesh electrodes, or patterned electrodes.

[0036] With continued reference to FIG. 2, the anode 102a and cathode 104a may be in any suitable arrangement within the device 100. For example, the anode 102a and cathode 104a may each be arranged in a plate and frame arrangement, a concentric tube arrangement, or a spiral wound arrangement, as shown in FIGS. 4A-4C. The plate and frame arrangement of FIG. 4A includes a set of electrodes at each end electrically connected in parallel, one set connected to a positive output from a DC power supply and the other set connected to a negative output. The electrodes in between are bipolar. The concentric tube arrangement of FIG. 4B includes an anode and cathode (or an anode-cathode pair) that are constructed and arranged to direct substantially all or all of the water having carbonate species passing through the active area or gap between the anode and cathode in a direction that is nearly or completely axially through the active area. The generally or entirely axial direction through the active area may be parallel or nearly parallel to the central axis of the electrochemical cell and / or the anode and cathode (or anode-cathode pair). Water having carbonate species flowing through the active area of ​​the anode 102a and cathode 104a may still be considered to flow generally or entirely axially through the active area even if the flow of water having carbonate species exhibits turbulence and / or eddies while passing through the active area.

[0037] The first cation permeable fluid separator 106 and the second cation permeable fluid separator 108 may be any suitable separation media capable of providing the desired ionic transport and physical properties for high flow rates and pressures during use of the device 100. For example, the materials used to fabricate one or both of the first cation permeable fluid separator 106 and the second cation permeable fluid separator 108 may be selected for high wear resistance, flexibility, and selective ion exchange, and the materials used to fabricate the fluid separators may incorporate one or more different materials. High wear resistance may be imparted by incorporating ceramic or oxide materials, flexibility may be imparted by incorporating polymeric species, and selective ion exchange may be achieved by specific chemical functionalization. In some embodiments, one or both of the cation permeable fluid separator 106 and the second cation permeable fluid separator 108 may be a cation exchange membrane. Alternatively, one or both of the cation permeable fluid separator 106 and the second cation permeable fluid separator 108 can be hard ceramic separators manufactured using processes such as low temperature hydrothermal liquid phase densification. Fluid separators manufactured using these processes can be formed into geometries that vary the functional surface area to volume ratio to improve device efficiency for acidification of water with carbonate species and product gas generation.

[0038] The apparatus 100 further includes a flow control system 101 constructed and arranged to independently control the flow of water having carbonate species through each of the anode compartment 102, the cathode compartment 104, and the central compartment 110. The flow control system 101 may be operatively coupled to elements used to control the flow of fluids, such as pumps 105 or valves, disposed throughout the apparatus 100. The apparatus 100 includes a flow meter or flow sensor 111 operatively coupled to the flow control system and disposed upstream or downstream of one or both of the anode compartment 102, the cathode compartment 104, and the central compartment 110. As illustrated, the flow meter or flow sensor 111 is disposed upstream of the anode compartment 102, the cathode compartment 104, and the central compartment 110, although the present disclosure also contemplates substantially equivalent flow meters or flow sensors disposed downstream of the anode compartment 102, the cathode compartment 104, and the central compartment 110.

[0039] 2, the apparatus 100 is connectable to a water source having carbonate species, e.g., saline water, e.g., seawater, brackish water, treated water retentate, or process water, as an inflow to each of the anode compartment 102, the cathode compartment 104, and the central compartment 110. The water source having carbonate species may be an independent water source 107a, 107b, or 107c connectable to the anode compartment 102, the cathode compartment 104, and the central compartment 110, respectively. Alternatively, the anode compartment 102, the cathode compartment 104, and the central compartment 110 may each be connectable to a single water source having carbonate species, in which case the water sources 107a, 107b, and 107c may each be the same water source having carbonate species.

[0040] The apparatus 100 includes one or more sensors located upstream or downstream of the anode compartment, the cathode compartment, and the central compartment constructed and arranged to measure one or more parameters of the water having carbonate species influent 107a, 107b, or 107c and / or effluent 109a, 109b, and 109c. The one or more sensors may include, for example, a flow meter, a water level sensor, a conductivity meter, a resistivity meter, a chemical concentration meter, a turbidity monitor, a chemical species ratio concentration sensor, a temperature sensor, a pH sensor, an oxidation-reduction potential (ORP) sensor, a pressure sensor, or any other sensor, probe, or scientific instrument useful for providing an indication of a desired property or parameter of the water having carbonate species entering any one or more of the anode, cathode, and central compartments, or the water having effluent therefrom. As shown in FIG. 2, the apparatus 100 includes a pH sensor 120 located downstream of the central compartment 110 and configured to measure the pH of the effluent 109c from the central compartment 110. The pH sensor 120 may be any type of suitable pH sensor. The apparatus 100 further includes a conductivity sensor 122 constructed and arranged to measure the conductivity between the anode 102a and the cathode 104a.

[0041] 2, the device 100 includes a controller 103 generally constructed and arranged to control the operation of the device 100. In some embodiments, the controller 103 is configured to receive a measurement of the pH of the effluent 109c from the central compartment 110 from the pH sensor 120. The controller 103 is configured to adjust, for example, by communicating with the flow control system 101, one or both of the flow rate of water having carbonate species from a water source having carbonate species 107c for the central compartment through the central compartment 110, or the current applied across the anode 102a and the cathode 104a to maintain the pH of the effluent 109c from the central compartment 110 at a predetermined level. This predetermined pH level is typically about 2.5 to about 6.5, for example, about 2.5, about 3, about 3.5, about 4, about 4.5, about 5, about 5.5, about 6, or about 6.5. The water having carbonate species effluents 109a, 109b, and 109c includes carbonate species, the predetermined level being determined when the majority of the carbonate species in the effluent 109c from the central section 110 is CO, as shown in equation (1). 2 and H 2 Carbonate H in equilibrium with O 2 CO 3 Without wishing to be bound by any particular theory, the production of hydrogen ions in the anode compartment and the consumption of hydrogen ions in the central compartment are correlated with the flow of water through the respective compartments. Thus, by controlling the flow of water through these compartments, it is possible to control the pH of the central compartment effluent 109c.

[0042] In some embodiments, the output from the conductivity sensor 122 is transmitted to the controller 103 and used by the controller 103 to determine whether to adjust the flow rate of one or more waters having carbonate species through the apparatus 100. Adjusting the flow rate of the water having carbonate species into and out of the apparatus 100 can adjust the production of acidified water having carbonate species, i.e., pH, through the central compartment 110, improve the efficiency of the apparatus 100, reduce the energy consumption of the apparatus 100, and reduce maintenance downtime. In some embodiments, the controller 103 is configured to adjust the flow rate of the water having carbonate species from the cathode inflow 107b through the cathode compartment 104 in response to the conductivity measurements from the conductivity sensor 122.

[0043] In some embodiments, the controller 103 may receive conductivity measurements from one or more conductivity sensors positioned to measure the conductivity of one or more of the effluents 109a, 109b, and 109c from the anode compartment, the cathode compartment, and the central compartment, respectively. The conductivity measurements from the effluents 109a, 109b, and 109c from the anode compartment, the cathode compartment, and the central compartment, respectively, are used by the controller 103 to control the acidification of the water in the central compartment and the CO 2 It may be determined how to regulate the flow of water through each compartment individually, or through a combination of individual compartments, to control the production of.

[0044] The measurements from the conductivity sensor 122 are indicative of the formation of ionic scale on the cathode 104a, and increasing the flow rate through the cathode compartment 104 reduces the likelihood of further scaling on the cathode 104a. In some embodiments, the controller 103 is configured to adjust the flow rate of the effluent 109a from the anode compartment 102 to the cathode compartment 104 in response to the conductivity measurements from the conductivity sensor 120. The measurements from the conductivity sensor 122 are indicative of the formation of ionic scale on the cathode 104a, and increasing the flow rate of the effluent 109a from the anode compartment 102 to the cathode compartment 104 reduces the likelihood of further scaling on the cathode 104a. In addition, as shown in equations (2)-(4), the chemical reaction in the cathode compartment 104 produces NaOH, which is caustic and may cause degradation of the second cation permeable fluid separator 108 or degradation of the cathode 104a. Recirculating water from recirculation line 118 to the cathode compartment 104 reduces the NaOH concentration therein, reducing scaling on the cathode 104a and extending the life of the apparatus 100. In some embodiments, the controller 103 is configured to minimize the flow rate of water having carbonate species from the cathode inflow 107b through the cathode compartment 104 to a flow rate at which no scale forms on the cathode. As used in the context of this disclosure, scale on the cathode generally can include any coating on the electrode that forms from precipitating species such as precipitated carbonates and oxides that form as the pH of the water changes during processing. As scale forms on the cathode, the surface area of ​​the active area of ​​the cathode is reduced, reducing the amount of H2O produced by the reduction of water. 2 The efficiency of the cathode for gas formation may be reduced. The flow rate and / or velocity of the water through the cathode compartment may be adjusted to reduce the amount of H in the center compartment while maintaining sufficient flow through the device to reduce the deposition of scale that may adsorb on the cathode. 2 The formation of CO 2 The flow rate can be adjusted, ie, reduced, to balance the gas production.

[0045] In some embodiments, the controller 103 is configured to adjust the flow rate of the water having carbonate species from the anode influent 107a through the anode compartment 102 in response to the conductivity measurements from the conductivity sensor 120. In some embodiments, the controller 103 adjusts the flow rate of the water having carbonate species from the anode influent 107a through the anode compartment 102 in response to the conductivity measurements from the conductivity sensor 120. In some embodiments, the controller 103 adjusts the flow rate of the water having carbonate species from the anode influent 107a through the anode compartment 102 in response to the conductivity measurements from the conductivity sensor 120 in response to the conductivity measurements from the conductivity sensor 120. 2 The flow rate is configured to minimize flow rates that do not result in clogging of the anode 102a by oxygen. As used herein, clogging on an electrode generally refers to gas bubbles attaching to a portion of the active area of ​​an electrode, e.g., the active area of ​​an anode, reducing the efficiency of further gas production when energized. Anode clogging can generally be assessed by measuring the volume of gas produced from an electrochemical process and comparing the measured volume to that theoretically predicted based on the relevant half-reactions, or by measuring the conductance across the anode / cathode pair. The water flow rate and / or flow rate through the anode compartment is adjusted to minimize O2 generation in the central compartment while maintaining sufficient flow through the device to reduce the formation of bubbles that may adsorb on the anode. 2 Gas formation followed by CO 2 The flow rate can be adjusted, ie, reduced, to balance the formation of gas.

[0046] Without wishing to be bound by any particular theory, an increase in flow rate generally reduces the residence time of the water with carbonate species in the cathode compartment, thereby reducing the time that ions in the water with carbonate species are in contact with the charged surface of the cathode. This reduces the O2 concentration on the anode due to the reduced residence time through the anode compartment. 2For example, the flow rate of water having carbonate species through the device is about 0.1 m / s to about 10 m / s, e.g., about 0.1 m / s to about 10 m / s, about 0.5 m / s to about 9 m / s, about 1 m / s to about 8 m / s, about 2 m / s to about 7 m / s, about 3 m / s to about 6 m / s, or about 4 m / s to about 5 m / s, e.g., about 0.1 m / s, about 0.5 m / s , about 1 m / s, about 1.5 m / s, about 2 m / s, about 2.5 m / s, about 3 m / s, about 3.5 m / s, about 4 m / s, about 4.5 m / s, about 5 m / s, about 5.5 m / s, about 6 m / s, about 6.5 m / s, about 7 m / s, about 7.5 m / s, about 8 m / s, about 8.5 m / s, about 9 m / s, about 9.5 m / s, or about 10 m / s. In certain embodiments, the flow rate of the water having carbonate species through the device may be between about 2 m / s and 3 m / s.

[0047] The controller 103 may be implemented using one or more computer systems. The computer system may be, for example, a general-purpose computer, such as a computer based on an Intel CORE® type processor, an Intel XEON® type processor, an Intel CELERON® type processor, an AMD FX type processor, an AMD RYZEN® type processor, an AMD EPYC® type processor, and an AMD R-series or G-series processor, or other types of processors, or a combination thereof. Alternatively, the computer system may include a programmable logic controller (PLC), specially programmed dedicated hardware, such as an application specific integrated circuit (ASIC), or a controller for an analytical system. In some embodiments, the controller 103 may be operably connected or connectable to a user interface constructed and arranged to allow a user or operator to view relevant operating parameters of the device 100, adjust said operating parameters, and / or stop operation of the device 100 as needed. The user interface may include a graphical user interface (GUI) including a display configured to be interacted with by a user or service provider and to output status information of the device 100.

[0048] The controller 103 may include one or more processors typically connected to one or more memory devices, e.g., disk drive memory, which may comprise any one or more of disk drive memory, flash memory devices, RAM memory devices, or other devices for storing data. The one or more memory devices may be used to store programs and data during operation of the apparatus 100. For example, the memory devices may be used to store historical data regarding parameters over a period of time. Software including programming code implementing embodiments of the present invention may be stored in a computer-readable and / or writable non-volatile recording medium and then typically copied to one or more memory devices and executed by one or more processors. Such program code may be written in any of a number of programming languages, e.g., ladder logic, Python, Java, Swift, Rust, C, C#, or C++, G, Eiffel, VBA, or various combinations thereof.

[0049] 2, the apparatus 100 includes one or more recirculation lines constructed and arranged to return a portion of the effluent from one or more of the anode effluent 109a, the cathode effluent 109b, and the central effluent 109c to one or more inlets of the anode compartment 102, the cathode compartment 104, and / or the central compartment 110. In some embodiments, the apparatus 100 includes a recirculation line 112 configured to recirculate at least a portion of the effluent 109a from the anode compartment 102 to the inlet of the anode compartment 102. In an alternative embodiment, as shown in FIG. 3, a portion of the effluent 109c from the central compartment 110 may be directed to an inlet of one of both the anode compartment 102 via conduit 115a and the cathode compartment 104 via conduit 115b. The effluent 109c from the central compartment 110 can be used to reduce the pH of the influent to the anode compartment 102, which can improve the efficiency of oxygen generation, e.g., H+ availability, in the anode compartment 102. The effluent 109c from the central compartment 110 can be used to reduce the total carbonate species concentration in the cathode compartment 104, which can reduce scale formation on the cathode 104a.

[0050] In some embodiments, the apparatus 100 includes a recirculation line 114 configured to recirculate at least a portion of the effluent 109b from the cathode compartment 104 to the inlet of the cathode compartment 104. The recirculation line 114 from the effluent 109b from the cathode compartment 104 to the inlet of the cathode compartment 104 may further include an in-line treatment system 124 to reduce the concentration of divalent species present in the cathode compartment effluent 109b. For example, the in-line treatment system 124 may include, but is not limited to, one or more of nanofiltration, reverse osmosis, ion exchange treatment, nanobead treatment, electrodeionization, and electrostatic deionization. An in-line treatment system may be used to reduce the scaling potential of the cathode 104a if it is determined that the high water velocity through the cathode compartment 104 is not sufficient to reduce the scaling potential. In some embodiments, the apparatus 100 includes a second recirculation line 116 configured to recirculate at least a portion of the effluent 109a from the anode compartment to the inlet of the cathode compartment 104. In some embodiments, the apparatus 100 includes a recirculation line 117 configured to recirculate at least a portion of the effluent from the central compartment 109c to the inlet of the central compartment 110.

[0051] In some embodiments, the apparatus 100 includes gas recovery systems 113a, 113b, 113c constructed and arranged to remove one or more dissolved gases from the effluent from one or more of the anode compartment 102, the cathode compartment 104, or the central compartment 110. As shown in Figure 2, the effluents 109a, 109b, and 109c from the anode compartment 102, the cathode compartment 104, or the central compartment 110 have gas recovery systems 113a, 113b, and 113c. Alternatively, the apparatus 100 may include one gas recovery system connectable to each of the outlets for the effluents 109a, 109b, and 109c from the anode compartment 102, the cathode compartment 104, or the central compartment 110, respectively. The gas recovery system 113a, 113b, 113c can be any suitable system capable of removing dissolved gases from the water, including, but not limited to, a forced draft degasser, a barrier tank, a vacuum stripper, an air stripper, or a membrane degasser. In certain embodiments, the gas recovery system includes one or more vacuum strippers. The gas recovery system removes H, 109a, 109b, 109c from one or more of the effluents 109a, 109b, 109c from the anode compartment 102, the cathode compartment 104, and / or the central compartment 110. 2 , CO 2 , and O 2 The gas recovery system is constructed and arranged to remove one or more of the following: H 2 , CO 2 , and / or O 2 In certain embodiments, the gas recovery system may be configured to remove at least 80% of the H from one or more of the effluents 109a, 109b, 109c from one or more of the anode compartment 102, the cathode compartment 104, or the central compartment 110. 2 , CO 2 , and O 2 The antibody may be configured to remove at least 90%, at least 95%, at least 99%, at least 99.9%, at least 99.99%, 99.999%, or 100% of the antibody.

[0052] According to one aspect, a method of producing hydrogen, carbon dioxide, and oxygen from seawater is provided. The method may include introducing seawater into each of an anode compartment, a cathode compartment, and a central compartment of an electrolysis cell. The method may include maintaining one or both of a flow rate through the central compartment or a current across the anode and cathode at a level that results in an effluent from the central compartment having a pH within a predetermined range. The method may further include maintaining a flow rate through the cathode compartment at a level that mitigates the formation of scale on the cathode. The method may further include maintaining a flow rate through the anode compartment at a level that mitigates clogging of the anode. The method may further include removing one or more of hydrogen, carbon dioxide, or oxygen from an effluent from each of one or more of the anode compartment, the central compartment, or the cathode compartment. The electrolysis cell may include an anode, a cathode, a first cation permeable fluid separator spaced from the anode and defining an anode compartment, a second cation permeable fluid separator spaced from the cathode and defining a cathode compartment, a central compartment defined between the first and second cation permeable fluid separators, and a flow control system configured to independently control the flow of seawater through each of the anode compartment, the cathode compartment, and the central compartment.

[0053] In some embodiments, the method may further include maintaining a flow rate through the cathode compartment at a minimum level that mitigates the formation of scale on the cathode. In some embodiments, the method may further include maintaining a flow rate through the anode compartment at a minimum level that mitigates gas clogging of the anode.

[0054] The method of producing hydrogen, carbon dioxide, and oxygen from seawater may further include introducing a portion of the effluent from the anode compartment to an inlet of the anode compartment together with the seawater introduced to the anode compartment to reduce gas production and clogging of the anode by the generated gas. In some embodiments, the method may further include introducing a portion of the effluent from the anode compartment to an inlet of the cathode compartment together with the seawater introduced to the anode compartment to reduce the concentration of caustic species generated in the cathode compartment. In some embodiments, the method may further include introducing a portion of the effluent from the cathode compartment to an inlet of the cathode compartment together with the seawater introduced to the cathode compartment to reduce the formation of scale on the cathode. In some embodiments, the method may further include introducing a portion of the effluent from the central compartment to an inlet of the central compartment together with the seawater introduced to the central compartment to balance the CO 2 The method may further include the step of shifting the direction of gas generation.

[0055] A method for producing hydrogen, carbon dioxide, and oxygen from seawater may include maintaining a flow rate through at least one of the anode compartment, the cathode compartment, or the central compartment at a different level than at least one other of the anode compartment, the cathode compartment, or the central compartment. In some embodiments, the method may further include maintaining the flow rate through the cathode compartment at a higher flow rate than the flow rate through the central compartment to reduce scaling on the cathode and reduce the concentration of caustic species, e.g., NaOH, formed in the cathode compartment.

[0056] The phrases and terms used herein are for purposes of description and should not be considered limiting. As used herein, the term "plurality" refers to two or more items or components. The terms "comprising," "including," "carrying," "having," "containing," and "involving," whether in the specification or claims, are intended to be open-ended terms, i.e., "including, but not limited to." Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases "consisting of" and "consisting essentially of" are closed or semi-closed transitional phrases, respectively, with respect to the claims. The use of ordinal terms such as "first," "second," "third," etc. in the claims to modify a claim element does not, in and of itself, imply a priority, seniority, or ordering of one claim element over another claim element, or the temporal order in which method operations are performed, nor does it imply any importance over another claim element or the temporal order in which method operations are performed, but is merely used as a marker to distinguish one claim element having a particular name from another element having the same name (but for the use of ordinal terms) in order to distinguish the claim elements.

[0057] Having thus described several aspects of at least one embodiment, it should be understood that various changes, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such changes, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0058] Those of ordinary skill in the art should understand that the parameters and configurations described herein are exemplary and that the actual parameters and / or configurations will depend on the particular application for which the disclosed methods and materials are used. Those of ordinary skill in the art should also recognize, or be able to ascertain using no more than routine experimentation, equivalents to the specific embodiments disclosed.

Claims

1. An apparatus for producing carbon dioxide and hydrogen from water having a carbonate species containing NaCl and / or NaHCO3, A scattered section and an anode located on the first side of the anode section, Cathode section and, A cathode located on the first side of the cathode compartment, A first cation exchange membrane is disposed on the second side of the anode section, A second cation exchange membrane is disposed on the second side of the cathode compartment, A central compartment defined between the first cation exchange membrane and the second cation exchange membrane, A flow control system configured to independently control the flow of water through each of the anode section, the cathode section, and the central section, A conductivity sensor configured to measure the conductivity of one or more outflows from the anode section, the cathode section, and the central section, A controller configured to adjust the flow rate of the water passing through the cathode section in response to the conductivity measurement value from the conductivity sensor, A device equipped with the following features.

2. The apparatus according to claim 1, further comprising a water source that can be fluidly connected to each of the anode section, the cathode section, and the central section.

3. The apparatus according to claim 1, further comprising a pH sensor disposed downstream of the central compartment and configured to measure the pH of the outflow from the central compartment.

4. The apparatus according to claim 3, further comprising a controller configured to receive a pH measurement of the effluent from the central compartment from the pH sensor, and to adjust either or both of the flow rate of the water passing through the central compartment or the current applied across the anode and cathode, thereby maintaining the pH of the effluent from the central compartment at a predetermined level.

5. In the apparatus according to claim 4, the predetermined level is such that the majority of carbonate species in the outflow from the central compartment is H ２ CO ３ And the device is at a level where CO2 exists.

6. The apparatus according to claim 4, wherein the controller is configured to maintain the pH of the outflow from the central compartment within the range of 2.5 to 6.

5.

7. The apparatus according to claim 1, wherein the controller is further configured to adjust the flow rate of the water passing through the cathode section to a flow rate that does not cause scale formation on the cathode.

8. The apparatus according to claim 1, wherein the controller is further configured to adjust the flow rate of the water passing through the anode section in response to a conductivity measurement from the conductivity sensor.

9. The apparatus according to claim 1, further comprising a recirculation line configured to recirculate at least a portion of the outflow from the anode compartment to the inlet of the anode compartment.

10. The apparatus according to claim 1, further comprising a recirculation line configured to recirculate at least a portion of the outflow from the cathode compartment to the inlet of the cathode compartment.

11. The apparatus according to claim 10, further comprising a second recirculation line configured to recirculate at least a portion of the outflow from the anode section to the inlet of the cathode section.

12. The apparatus according to claim 11, wherein the controller is further configured to adjust the flow rate of at least a portion of the effluent from the anode section that is recirculated to the inlet of the cathode section via the second recirculation line in response to conductivity measurements from the conductivity sensor.

13. The apparatus according to claim 1, further comprising a recirculation line configured to recirculate at least a portion of the outflow from the central compartment to the inlet of the central compartment.

14. The apparatus according to claim 1, further comprising a recirculation line configured to recirculate at least a portion of the outflow from the central compartment to one or both of the inlets of the anode compartment and the cathode compartment.

15. The apparatus according to claim 1, further comprising a gas recovery system configured to remove one or more of hydrogen, carbon dioxide, or oxygen from one or more of the effluents from the anode section, the cathode section, or the central section.

16. The apparatus according to claim 15, wherein the gas recovery system includes one or more vacuum strippers.

17. The apparatus according to claim 1, wherein the anode includes an oxygen-evolving coating comprising iridium suboxide, magnesium phase titanium dioxide, stainless steel, iridium-cobalt (Ir-Co), iridium-tantalum (Ir-Ta), or one of other iridium or tantalum species.

18. A method for producing hydrogen, carbon dioxide, and oxygen from seawater, The step involves introducing seawater into the anode, cathode, and central compartments of the electrolytic cell, and the electrolytic cell is, A-scatter, Cathode and, A first cation exchange membrane is spaced apart from the anode and defines the anode compartment, A second cation exchange membrane is spaced apart from the cathode and defines the cathode compartment, A central compartment defined between the first cation exchange membrane and the second cation exchange membrane, and A flow control system configured to independently control the flow of seawater through each of the anode section, the cathode section, and the central section, The steps include introducing the seawater, A step of removing one or more of hydrogen, carbon dioxide, or oxygen from the effluent from one or more of the anode compartment, the central compartment, or the cathode compartment, respectively. The steps include measuring the conductivity of one or more of the outflows from the anode section, the cathode section, and the central section, The steps include adjusting the flow rate of the water passing through the cathode section in response to the conductivity measurement value from the conductivity sensor, A method that includes [a certain feature].

19. A method according to claim 18, further comprising the step of introducing a portion of the outflow from the anode compartment into the inlet of the anode compartment together with the seawater introduced into the anode compartment.

20. A method according to claim 18, further comprising the step of introducing a portion of the outflow from the anode compartment into the inlet of the cathode compartment together with the seawater introduced into the cathode compartment.

21. A method according to claim 18, further comprising the step of introducing a portion of the outflow from the central compartment into the entrance of the central compartment together with the seawater introduced into the central compartment.

22. A method according to claim 18, further comprising the step of maintaining the flow rate through at least one of the anode section, the cathode section, or the central section at a different level from the other of the at least one of the anode section, the cathode section, or the central section.

23. A method according to claim 22, further comprising the step of maintaining the flow rate through the cathode section at a higher flow rate than the flow rate through the central section.

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