Integrated direct air capture and electrochemical reduction of carbon dioxide.

Abstract

The present disclosure provides systems and methods for integrated direct air capture of reactants from the atmosphere for use in aqueous electrochemical CO reduction processes. Using integrated direct air capture methods for CO, cost-effective production of fuels and materials can be achieved through the electrochemical conversion of CO.

Description

[Technical field]

[0001] cross reference This application claims the benefit of U.S. Provisional Patent Application No. 63 / 151,303, filed February 19, 2021, U.S. Provisional Patent Application No. 63 / 188,238, filed May 13, 2021, U.S. Provisional Patent Application No. 63 / 217,207, filed June 30, 2021, and U.S. Provisional Patent Application No. 17 / 317,686, filed May 11, 2021, each of which is incorporated by reference in its entirety. [Background technology]

[0002] The levels of carbon-containing compounds such as carbon monoxide (CO) and carbon dioxide (CO2) in the atmosphere are increasing. These increasing levels of carbon-containing compounds can have a negative impact on the Earth's temperature, which can lead to global warming. Summary of the Invention

[0003] The present disclosure provides systems and methods for integrated direct air capture of reactants from the atmosphere for use in aqueous electrochemical carbon dioxide (CO2) reduction processes. Using integrated direct air capture of CO2, cost-effective production of fuels and materials through electrochemical conversion of CO2 can be achieved.

[0004] It is recognized herein that there is a growing need for efficient methods to produce fuels and other chemicals from non-petroleum based resources and reduce atmospheric CO2 levels. Although it has long been known that the electrocatalytic reduction of CO2 to fuels and materials (e.g., building materials) is technically feasible, it has not been economically practical, in part, due to low catalytic efficiency for the most useful products (such as liquid transportation fuels and polymer monomers), and due to the costs of capturing CO2 from the atmosphere, separating the reduced carbon materials (e.g., water-miscible products that require distillation, such as ethanol), and upgrading the reduced products to end products.

[0005] Carbon species that may be produced by electrochemical reduction of CO2 (i.e., the addition of electrical energy in the form of chemical bonds) include many hydrocarbon gases (such as carbon monoxide), alcohols, aldehydes, organic acids, and, to a lesser extent, long-chain hydrocarbons. Of these, many may have potential for conversion to useful products such as transportation fuels and polymers. Methods for capturing CO2 from air have included the use of a material sufficient to capture CO2 in contact with air to capture CO2 that is present in low concentrations but has a relatively high chemical reactivity. The material sufficient to capture CO2 can be a sorbent or absorbent material. In some cases, the material sufficient to capture CO2 may be a solvent configured to dissolve CO2. The sorbent may include a solid sorbent having reactive functional groups. The absorbent may include an aqueous hydroxide solution, a non-aqueous reactive liquid, and the like. In some cases, the material sufficient to capture CO2 may be an electrolyte solution. In some cases, the electrolyte solution may be aqueous or non-aqueous. In previous examples, the goal was to produce a pure CO2 gas stream, which involved a high degree of change in the entropy of the gas. An integrated CO2 capture process in which CO2 is dissolved in an electrolyte such as a bicarbonate / carbonate solution would require a much smaller entropy change than converting it to a pure gas. This could result in significant energy savings. Furthermore, capturing CO2 in the electrolyte used in the electrochemical CO2 reduction process could significantly reduce capital equipment and process complexity.

[0006] In one aspect, described herein is an integrated direct air capture method of carbon dioxide (CO) for aqueous electrochemical reduction of CO, the method comprising: (a) capturing at least a portion of the CO from an incoming air stream, the incoming air stream comprising CO, by contacting the incoming air stream with an electrolyte solution; and (b) reducing at least a portion of the CO using the electrolyte solution to produce a reduced carbon product.

[0007] In some embodiments, the capture of at least a portion of the CO2 comprises absorption or adsorption by the electrolyte solution.

[0008] In some embodiments, the incoming air stream has a CO2 concentration of up to 1000 ppm. In some embodiments, the incoming air stream has a CO2 concentration of up to 500 ppm. In some embodiments, the incoming air stream has a CO2 concentration of up to 420 ppm.

[0009] In some embodiments, the incoming air stream includes water (HO), and subsequent to (a), at least a portion of the HO is absorbed by the electrolyte solution. In some embodiments, the method further includes controlling a temperature or range of the electrolyte solution to facilitate capture of the HO.

[0010] In some embodiments, the reduction in (b) is in the absence of an independent hydrogen supply to the electrolyte solution.

[0011] In some embodiments, (a) includes flowing the electrolyte solution from a first electrolyte reservoir to a contactor, where the incoming air stream and the electrolyte solution are contacted at the contactor. In some embodiments, the method further includes directing the electrolyte solution to a second electrolyte reservoir. In some embodiments, the first electrolyte reservoir is different from the second electrolyte reservoir. In some embodiments, the first electrolyte reservoir is the same as the second electrolyte reservoir.

[0012] In some embodiments, the contactor comprises a material sufficient to capture CO2 and facilitate adsorption of at least a portion of the CO2 from the incoming air stream. In some embodiments, the material sufficient to capture CO2 comprises water. In some embodiments, the material sufficient to capture CO2 comprises a solid substrate comprising a reactive chemical sorbent. In some embodiments, the material sufficient to capture CO2 comprises polystyrene beads functionalized with amines. In embodiments, the material sufficient to capture CO2 comprises an activated or nanostructured carbon material. In embodiments, the activated or nanostructured carbon material comprises carbon nanotubes (CNTs), buckminsterfullerenes, and graphene.

[0013] In some embodiments, the contactor comprises one or more components selected from the group consisting of a membrane contactor, a random or structured gas-liquid contacting packing, a film fill, a splash packing, a packed falling film device, a cooling tower, a fluidized bed, a liquid shower in contact with a gas, and a nanostructured or activated carbon material. In some embodiments, the contactor comprises a carbon nanotube membrane, a plurality of nanotubes of the carbon nanotube membrane function as pores, and a plurality of openings of the plurality of nanotubes are functionalized with an adsorptive functional group.

[0014] In some embodiments, the method further comprises controlling a pH or range thereof of the electrolyte solution (i) before or (ii) after said contacting of the incoming air stream and the electrolyte solution. In some embodiments, the controlling comprises adjusting or maintaining a pH range of the electrolyte solution between 9 and 15. In some embodiments, the controlling comprises adjusting or maintaining a pH range of the electrolyte solution between 7 and 10.

[0015] In some embodiments, the method further comprises controlling a pH or range thereof of the electrolyte solution after said contacting of the incoming air stream and the electrolyte solution, in some embodiments, said controlling comprises adjusting or maintaining a pH range of the electrolyte solution between 7 and 10.

[0016] In some embodiments, the method further includes adjusting a pH or range thereof of the electrolyte solution (i) before or (ii) after the contacting of the incoming air stream and the electrolyte solution with a pH control unit. In some embodiments, the pH control unit includes (i) a bipolar membrane stack configured to increase the pH of the electrolyte solution when flowing through the pH control unit in a first direction and to decrease the pH of the electrolyte solution when flowing through the pH control unit in a second direction different from the first direction, and (ii) an electrochemical stack configured to increase the pH of the electrolyte solution when flowing through the pH control unit in a first direction and to decrease the pH of the electrolyte solution when flowing through the pH control unit in a second direction different from the first direction by reducing at least a portion of the CO2 and hydrogen while generating oxygen. In some embodiments, the pH control unit includes an acid and base supply unit configured to (i) supply an acidic solution to the electrolyte solution following the contacting of the air flow and the electrolyte solution to lower the pH or range thereof of the electrolyte solution, and (ii) supply a basic solution to the electrolyte solution prior to the contacting of the air flow and the electrolyte solution to raise the pH or range thereof of the electrolyte solution.

[0017] In some embodiments, the method further includes, prior to (a), contacting a first electrolyte solution with a CO2-containing liquid material sufficient to capture CO2 and outputting the electrolyte solution. In some embodiments, following (b), contacting the electrolyte solution with the first electrolyte solution. In some embodiments, the liquid material sufficient to capture CO2 comprises one or more members selected from the group consisting of an aqueous hydroxide solution, an amine solution, and an ionic liquid. In some embodiments, the first electrolyte solution and the liquid material sufficient to capture CO2 are contacted with a bipolar membrane stack including an anion exchange membrane or a cation exchange membrane stack or both, the bipolar membrane stack or the cation exchange membrane stack configured to facilitate transport of carbon-containing species from the liquid material sufficient to capture CO2 to the first electrolyte solution.

[0018] In some embodiments, at least a portion of the carbon dioxide is reduced using the electrolyte solution to produce reduced carbon products.

[0019] In some embodiments, the reduced carbon products include a fuel.

[0020] In another embodiment, those described herein have a -25‰Δ 13 It is a composition that contains a mixture of hydrocarbons that contain carbon with an isotopic distribution higher than C.

[0021] In some embodiments, the hydrocarbon mixture has a viscosity of -6‰ to -9‰Δ 13 In some embodiments, the hydrocarbon mixture has carbon with an isotopic distribution of 10 to 150 C. In some embodiments, the hydrocarbon mixture has no detectable sulfur. In some embodiments, the hydrocarbon mixture has no detectable aromatic compounds. In some embodiments, the hydrocarbon mixture has no detectable metal compounds.

[0022] In one aspect, described herein is a method for producing a gas turbine engine comprising: providing an enclosure including an electrochemical reduction system including an electrolyte solution, an anode, and a cathode; directing an incoming air stream into the enclosure thereby contacting the incoming air stream with the electrolyte solution in the enclosure, wherein the incoming air stream includes CO2. ], capturing the CO2 from the incoming air stream in the electrolyte solution to generate first bicarbonate ions; and reducing the first bicarbonate ions to generate a carbon product while applying a voltage between the cathode and the anode, wherein the electrochemical reduction system is used to adjust the pH of the electrolyte solution to facilitate capture of the CO2 in the electrolyte solution or to facilitate CO2 reduction, and the generation of the carbon product in (c) (1) produces hydroxide ions, which convert second bicarbonate ions to carbonate ions, and (2) regenerate carbonate or bicarbonate ions to maintain (i) an optimal pH for reducing additional CO2, or (ii) an optimal concentration of carbonate or bicarbonate ions for reducing additional CO2.

[0023] In some embodiments, the capture of the CO2 includes absorption by an electrolyte solution. In some embodiments, the incoming air stream has a CO2 concentration of up to 500 parts per million (ppm). In some embodiments, the incoming air stream includes HO, and after (b), at least a portion of the HO is absorbed by an electrolyte solution. In some embodiments, the method further includes controlling a temperature or range of the electrolyte solution to facilitate capture of the HO. In some embodiments, the reduction in (c) is performed in the absence of an independent hydrogen supply to the electrolyte solution.

[0024] In some embodiments, the housing includes a contactor, and in (b), the inlet air stream and the electrolyte solution are contacted at the contactor. In some embodiments, the method further includes directing the electrolyte solution to an electrolyte reservoir. In some embodiments, the contactor includes a sorbent to facilitate capture of the CO2 from the inlet air stream into the electrolyte solution. In some embodiments, the sorbent includes a solid substrate including a reactive chemical sorbent selected from the group consisting of polystyrene beads functionalized with amines, carbon nanotubes (CNTs), buckminsterfullerenes, and graphene. In some embodiments, the contactor includes one or more components selected from the group consisting of a membrane contactor, a random or structured gas-liquid contacting packing, a film fill, a splash packing, a packed falling film device, a cooling tower, a fluidized bed, a liquid shower in contact with a gas, and a nanostructured or activated carbon material. In some embodiments, the membrane contactor includes a carbon nanotube membrane, a plurality of nanotubes of the carbon nanotube membrane function as pores, and a plurality of openings of the plurality of nanotubes are functionalized with an adsorptive functional group.

[0025] In some embodiments, the pH control unit adjusts or maintains a pH range of the electrolyte solution between 9 and 15 or between 7 and 10. In some embodiments, the pH control unit includes (i) a bipolar membrane stack, (ii) an electrochemical stack configured to reduce CO2 and hydrogen while generating oxygen to increase the pH of the electrolyte solution when flowing through the pH control unit in a first direction and to decrease the pH of the electrolyte solution when flowing through the pH control unit in a second direction different from the first direction, or (iii) an acid and base supply unit configured to (1) supply an acidic solution to the electrolyte solution after the contact of the air stream and the electrolyte solution to decrease the pH or range thereof of the electrolyte solution, and (2) supply a basic solution to the electrolyte solution before the contact of the air stream and the electrolyte solution to increase the pH or range thereof of the electrolyte solution.

[0026] In some embodiments, the method further includes contacting the first electrolyte solution with a solution comprising one or more members selected from the group consisting of an aqueous hydroxide solution, an amine solution, and an ionic liquid to output the electrolyte solution. In some embodiments, after (c), the electrolyte solution is contacted with the first electrolyte solution. In some embodiments, the first electrolyte solution and the solution are contacted at a bipolar membrane stack. In some embodiments, the electrochemical reduction system includes a membrane. In some embodiments, the membrane includes a plurality of pores. In some embodiments, the membrane includes a catalyst. In some embodiments, a pH control unit is separate from the housing. In some embodiments, the housing includes a compartment.

[0027] Further aspects and advantages of the present disclosure will become readily apparent to those skilled in the art from the following detailed description, in which only illustrative embodiments of the present disclosure are shown and described. As will be understood, the present disclosure is capable of other and different embodiments, and its several details are capable of modification in various obvious respects, all without departing from the present disclosure. Accordingly, the drawings and description should be regarded as illustrative in nature, and not restrictive.

[0028] Incorporation by Reference All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent that the publications and patents or patent applications incorporated by reference conflict with the disclosure contained in this specification, the specification shall take precedence and / or supersede any such conflicting content.

[0029] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also referred to herein as "FIG."). [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram of a method for capturing CO2, according to an embodiment. [Diagram 2] FIG. 13 is an additional schematic diagram of a method for capturing CO2 including a pH control method, according to an embodiment. [Diagram 3] FIG. 13 is an additional schematic diagram of a method for capturing CO2 including a pH control method, according to an embodiment. [Figure 4] FIG. 13 is an additional schematic diagram of a CO2 capture method including a pH control method to increase the pH of one input stream and decrease the pH of another input stream, according to an embodiment. [Diagram 5] FIG. 13 is an additional schematic diagram of a method for capturing CO2, including two methods for pH control and separate methods for generating acid and base streams, according to an embodiment. [Figure 6] 2 is an additional schematic diagram of a method of capturing CO2, including a contactor that includes a material sufficient to capture CO2, according to an embodiment. [Figure 7] FIG. 13 is an additional schematic diagram of a method for capturing CO2, including a pH control device and two contactors, according to an embodiment. [Figure 8] 1 is an additional schematic diagram of a method for capturing CO2, including two contactors, in one of which a liquid material sufficient to capture CO2 is contacted with a CO2-containing liquid, according to an embodiment. [Figure 9] 1A-1C show a surface of a carbon nanotube film in which the tubes act as pores through an inert material matrix, according to an embodiment. [Figure 10] 1A-1D illustrate hollow fiber carbon nanotube membranes, according to embodiments. [Figure 11]FIG. 2 illustrates a carbon nanotube pore functionalized with a desired functional group, according to an embodiment. [Figure 12] 1 is a schematic diagram of a computer system utilized in the present invention, according to an embodiment; [Figure 13A] 13A is a schematic diagram of an example of a separation unit of an electrochemical reduction system including a first compartment having a cathode and a second compartment having an anode, in which the anode and cathode are electrically coupled by a power source. [Figure 13B] 13A and 13B are schematic diagrams of an example of a separation unit of an electrochemical reduction system including a first compartment having a cathode and a second compartment having an anode, in which the anode and cathode are separated by a membrane; [Figure 13C] 13A-13C are schematic diagrams of an example of a separation unit of an electrochemical reduction system including a first compartment having a cathode and a second compartment having an anode, and FIG 13C is a schematic diagram of a separation unit including an extractor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] While various embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the present invention described herein may be used.

[0032] Whenever the term "at least," "more than," or "more than or equal to" appears before the first number in a series of two or more numbers, the term "at least," "more than," or "more than or equal to" applies to every number in the series. For example, 1, 2, or 3 or more is equivalent to 1 or more, 2 or more, or 3 or more.

[0033] Whenever the term "no more than", "less than" or "less than or equal to" appears before the first number in a series of two or more numbers, the term "no more than", "less than" or "less than or equal to" applies to every number in the series. For example, 3, 2 or 1 or less is equivalent to 3 or less, 2 or less, or 1 or less.

[0034] As used herein, the terms "C1+" and "C1+ compound" generally refer to compounds containing one or more carbon atoms, e.g., one carbon atom (C1), two carbon atoms (C2), etc. C1+ compounds include, but are not limited to, alkanes (e.g., methane, CH4), alkenes (e.g., ethylene, C2H2), alkynes, and aromatics containing two or more carbon atoms.

[0035] In some cases, C1+ compounds include aldehydes, ketones, esters, and carboxylic acids. Examples of C1+ compounds include, but are not limited to, methane, ethane, ethylene, acetylene, propane, propene, butane, butylene, etc. C1+ compounds may also be referred to as reduced carbon products or reduced carbon materials as used herein.

[0036] The term "unit" as used herein generally refers to a unit operation, which is a fundamental operation in a process. A unit operation may include, for example, a physical or chemical change, such as separation, crystallization, evaporation, filtration, polymerization, isomerization, conversion, and other reactions. In a given process, one or more unit operations may be required to obtain a desired product(s) from a starting material(s) or feedstock(s).

[0037] As used herein, the term "carbon-containing material" generally refers to any material that includes at least one carbon atom. In certain examples, the carbon-containing material is carbon monoxide (CO), carbon dioxide (CO2), or a mixture of CO and CO2. The carbon-containing material can be a material derived from CO and / or CO2, such as bicarbonate or bicarbonate ions.

[0038] As used herein, the term "pH control unit" generally refers to a unit operation used to adjust the pH of one or more input streams. In some examples, the pH control unit is a bipolar membrane stack. In some embodiments, the pH control unit is an electrochemical stack that reduces CO2. In some embodiments, the pH control unit is an acid or base delivery unit.

[0039] Provided herein are systems, devices and methods for the direct capture of CO2 from air, and processes thereof. The invention can include an integrated CO2 capture process in which CO2 is dissolved in an electrolyte. An incoming air stream containing CO2 can be withdrawn and placed into an electrochemical reduction system, which converts the CO2 into hydrocarbons.

[0040] The invention can include contacting the incoming air stream with an electrolyte solution, the incoming air stream including CO2, capturing at least a portion of the CO2 from the incoming air stream into the electrolyte solution, and using the electrolyte solution to reduce the at least a portion of the CO2 to produce a reduced carbon product, e.g., to produce a fuel. In some cases, the electrolyte solution can be regenerated after production of the reduced carbon product. In some embodiments, the regenerated electrolyte can be recycled within the system to facilitate additional CO2 capture. The described systems can include one or more additional chemical conversion processes that enable conversion of the CO2-derived reduced carbon products to hydrocarbon fuels or other useful chemical products.

[0041] The method can include contacting the incoming air stream with an electrolyte solution, the incoming air stream including CO, capturing at least a portion of the CO from the incoming air stream into the electrolyte solution, and reducing the at least a portion of the CO using the electrolyte solution to produce reduced carbon products, such as fuels or other useful chemical products.

[0042] The incoming air stream can include ambient air, such as air from an outdoor environment or an indoor environment. The incoming air stream can include ambient air. The incoming air stream can include a relatively low CO2 level. For example, the CO2 concentration in the incoming air stream can be up to about 2000 parts per million (ppm), 1800 ppm, 1600 ppm, 1400 ppm, 1200 ppm, 1000 ppm, 800 ppm, 600 ppm, 400 ppm, or less. The CO2 concentration in the incoming air stream can be equal to or less than the ambient concentration of CO2 in outdoor ambient air (e.g., 410 ppm). Alternatively, the incoming air stream can include non-ambient air. The non-ambient air can include a CO2 concentration that is up to about 2000 ppm, 1800 ppm, 1600 ppm, 1400 ppm, 1200 ppm, 1000 ppm, 800 ppm, 600 ppm, 400 ppm, or less. Alternatively, the incoming air stream can have a CO2 concentration of greater than about 2000 ppm. In some embodiments, the incoming air stream can be directed into a compartment (e.g., a first compartment or chamber) of the system. In some embodiments, the incoming air stream can be in contact with an electrolyte solution.

[0043] The present disclosure provides a chemical conversion system that converts CO2 to other chemicals via an electrochemical reduction system. The electrochemical reduction system can generate bicarbonate ions via capture of CO2 from atmospheric CO2. In some cases, the CO2 reduction system can utilize a feed stream that includes CO2 without the need for further purification. In some cases, the CO2 reduction system can use a feed stream that includes CO2 without the need for additional separation processes to enrich the CO2 composition of the feed stream. The feed stream to the electrochemical reduction system can include about 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.5%, 1%, 5%, 10%, 20%, 50%, 90%, 95% or more CO2 on a molar basis. The feed stream to the electrochemical reduction system can contain at least about 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.5%, 1%, 5%, 10%, 20%, 50%, 90%, 95% or more CO2 on a molar basis. The feed stream to the electrochemical reduction system can contain no more than about 95%, 90%, 50%, 20%, 10%, 5%, 1%, 0.5%, 0.2%, 0.1%, 0.09%, 0.08%, 0.07%, 0.06%, 0.05%, 0.04%, 0.03%, 0.02%, or 0.01% CO2 on a molar basis.

[0044] Electrochemical reduction systems can produce reduced carbon products (e.g., hydrocarbons) at a specific rate based on the surface area available for electrochemical reduction. Electrochemical reduction systems can produce reduced carbon products (e.g., hydrocarbons) at a rate of approximately 10 kg / m2 / hour (kg / m 2 / hour), 20kg / m 2 / hour, 30kg / m 2 / hour, 40kg / m 2 / hour, 50kg / m 2 / hour, 60kg / m 2 / hour, 70kg / m 2 / hour, 80kg / m 2 / hour, 90kg / m 2 / hour, 100kg / m 2 / hour, 150kg / m2 / hour, or about 200 kg / m 2 The electrochemical reduction system can produce reduced carbon products at a rate of at least about 10 kg / m 2 / hour, 20kg / m 2 / hour, 30kg / m 2 / hour, 40kg / m 2 / hour, 50kg / m 2 / hour, 60kg / m 2 / hour, 70kg / m 2 / hour, 80kg / m 2 / hour, 90kg / m 2 / hour, 100kg / m 2 / hour, 150kg / m 2 / hour, or about 200 kg / m 2 The electrochemical reduction system can produce reduced carbon products at rates of about 200 kg / m 2 / hour, 150kg / m 2 / hour, 100kg / m 2 / hour, 90kg / m 2 / hour, 80kg / m 2 / hour, 70kg / m 2 / hour, 60kg / m 2 / hour, 50kg / m 2 / hour, 40kg / m 2 / hour, 30kg / m 2 / hour, 20kg / m 2 / hour, or 10kg / m 2 Reduced carbon products can be produced at rates of up to 1 / hr.

[0045] An electrochemical reduction system may have a selectivity for converting CO2 to one or more chemical species. In some cases, selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are captured from the feed stream and converted to product species. For example, a selectivity of 50% may indicate that 50% of the incoming CO2 molecules are converted to reduced carbon species within the reactor, system, or unit. In some cases, selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are converted to species within a particular class, weight range, carbon number range, or other property. For example, a selectivity of 50% C1-C4 may indicate that 50% of the incoming CO2 molecules are converted to C1 to C4 reduced carbon products. The selectivity may be a single pass selectivity. The single pass selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are captured and converted to reduced carbon products in one pass through the reactor, system, or unit. The selectivity may be a recycle selectivity. Recycle selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are converted to hydrocarbon products in two or more passes through the reactor, system, or unit.

[0046] The electrochemical reduction system may have a selectivity of about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or about 99%. The electrochemical reduction system may have a selectivity of at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or about 99% or more. The electrochemical reduction system may have a selectivity of 99% or less, 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% or less.

[0047] An electrochemical reduction system for converting CO2 to other chemicals may include various components that may be necessary for the reduction of CO2. The components may include cathodes, anodes, contactors, extractors, pumps, gas-liquid separators, and ion exchange membranes. In some cases, some components may be included or excluded from the chemical reduction system depending on the preferred embodiment of the device. In some cases, the chemical reduction system may be a single standalone or fully integrated system that performs the entire process of electrochemical reduction of CO2. In other cases, the electrochemical reduction system may include at least two or more operably linked unit operations that collectively perform the processes necessary in the electrochemical reduction of CO2.

[0048] The electrochemical reduction system may include a housing. The housing may provide various functions to the electrochemical reduction system, such as, but not limited to, securing components (e.g., membranes), physically containing fluids, separating different fluids within a single unit, maintaining temperature or pressure, and / or providing insulation. The housing may include any suitable material, including metal, ceramic, refractory, insulating material, plastic, and glass. The housing may include one unit of the electrochemical reduction system (e.g., a cathode). The housing may include two or more units of the electrochemical reduction system (e.g., a cathode and an anode). The complete electrochemical reduction system may be contained within a single housing.

[0049] The housing may include one or more walls. The housing may include one or more compartments. The housing may have a cross-section that is circular, triangular, square, rectangular, pentagonal, hexagonal, or partial shaped, or a combination of shapes. The housing may be a single piece or may be formed from multiple pieces (e.g., pieces welded together). The housing may include a coating therein. Such a coating may prevent reactions with the interior surface of the housing, such as corrosion or oxidation / reduction reactions with the surface.

[0050] The electrochemical reduction system may include one or more compartments or chambers. A compartment or chamber may be defined as a closed volume in the electrochemical reduction system where mass transfer occurs. For example, the electrochemical reduction system may include a first compartment (or chamber) where the C1+ product is produced and a second compartment or chamber where the C1+ product is extracted, separated, or otherwise transferred from the first compartment. In some embodiments, the first compartment or chamber and the second compartment or chamber may include an electrolyte. In some embodiments, the one or more compartments or chambers may include an anode, a cathode, a membrane, or a combination thereof. In some embodiments, the second compartment or chamber may include an anode, a cathode, or a combination of cholera.

[0051] The electrochemical reduction system can include a contactor as described in Figures 1, 2, 3, 4, 5, 7, and 8, and can further include one or more compartments or chambers. A compartment or chamber can be defined as an enclosed volume within the electrochemical reduction system where mass transfer occurs. For example, the electrochemical reduction system can include a compartment or chamber in which the C1+ product is produced and another compartment or chamber in which the C1+ product is extracted, separated, or otherwise transferred from the first compartment.

[0052] 13A-13C show various examples of compartment or chamber configurations within the scope of the present invention. In some embodiments, the chamber or compartment can further include additional chambers or compartments. FIG. 13A depicts a schematic diagram of an electrochemical reduction system 1000 in which a first compartment or chamber 100 includes a cathode 140 and a second compartment or chamber 200 includes an anode 160, the anode 140 and the cathode 160 being electrically connected by a power source 130. The first compartment or chamber 100 is separated from the second compartment or chamber 200 by a micro- or nano-structured membrane 150 that controls the movement of the C1+ product from the first compartment or chamber 100 to the second compartment or chamber 200. FIG. 13B depicts a schematic diagram of an electrochemical reduction system 1000 including a cathode unit 240 and an anode unit 220. The cathode unit 240 includes a first compartment or chamber 100 including a cathode 140 electrically connected to an anode 160 in the anode unit 220 by a power supply 130. The first compartment or chamber 100 is separated from a second compartment or chamber 200 by a microstructured or nanostructured membrane 150 that controls the movement of the C1+ product from the first compartment 100 to a second compartment or chamber 200 in the cathode unit 240. FIG. 13C shows a schematic diagram of an electrochemical reduction system 1000 including a cathode unit 240, an anode unit 220, and an extractor 230. The cathode unit includes a cathode 140 and a first compartment 100. The cathode 140 is electrically connected to an anode 160 in the anode unit 220 by a power supply 130. The C1+ product is produced in a first compartment or chamber of the cathode unit 240 and is conveyed by stream C1+ to an extraction device that includes a second compartment or chamber 200. The C1+ product is transferred from stream C1+ to the second compartment or chamber 200 by passing through a micro- or nano-structured membrane 150.In some embodiments, the electrochemical reduction system can include a pH control unit within the chamber containing the contactor. In some embodiments, the electrochemical reduction system can include a pH control unit external to the chamber containing the contactor.

[0053] The electrochemical reduction system can include a cathode, an anode, and an electrolyte solution that collectively provide the necessary components for reducing CO2 to other chemical species. The electrolyte solution can include an aqueous salt solution configured to have an optimal ionic strength and pH for the electrochemical reduction of CO2. The electrolyte solution can include an aqueous salt solution including bicarbonate ions. In some cases, the electrolyte solution can include an aqueous solution of sodium bicarbonate or potassium bicarbonate. In some cases, the bicarbonate ions can dissociate in the presence of one or more catalysts to generate CO2 molecules for the reduction reaction. Dissolution of CO2 into the electrolyte solution can regenerate or maintain an optimal concentration of bicarbonate ions. The electrolyte solution can include an aqueous species including carbonate ions. The electrolyte solution can include an aqueous species including formate ions. Electrochemical conversion of bicarbonate compounds to reduced carbon products can produce hydroxide ions, which can shift some of the remaining bicarbonate ions to carbonate ions. Absorption of CO2 can shift the carbonate ions back to bicarbonate ions. Reduced organic salts, such as formates or acetates, can be further reduced to the desired reduced carbon products. Optionally, the electrolyte solution can be regenerated after generation of reduced carbon products. In some embodiments, the regenerated electrolyte can be recycled within the system to facilitate additional capture of CO2.

[0054] The anode can include elemental metals such as nickel, tin, or gold. The anode can comprise a wire mesh, metal foam, or other permeable structure of the selected anode material. The anode material may be in operative contact with an anion exchange membrane material or another physical separator that prevents contact with the cathode.

[0055] The cathode may include any suitable material. In some cases, the cathode may include copper nanoparticles and / or N-doped carbon nanomaterials. In some cases, the cathode may include a microstructured or nanostructured membrane material. In some cases, the cathode may include one or more catalysts for electrochemical reduction of CO or CO2, or other chemical reactions. The cathode material may be in operative contact with an anion exchange membrane material or another physical separator that prevents contact with the cathode. In some cases, the distance between the cathode and the anode may be minimized to reduce resistance. In some cases, forced convection of electrolyte between the electrodes may further reduce electrical resistance and / or further increase the distance between the electrodes. In some cases, the electrodes may be in different housings, chambers, or compartments. In some cases, the anode and cathode may have a minimal distance with an ion selective membrane between them. In some cases, an ion selective membrane may not be used.

[0056] The electrochemical reduction system can be configured to operate at an optimal voltage to reduce CO or CO2 to reduction products. The electrochemical reduction system can be arranged in a stacked configuration or a direct arrangement to adjust the system voltage to an optimal value. The electrochemical reduction system can have an operating voltage of about 0.1 volts (V), 0.2V, 0.3V, 0.4V, 0.5V, 0.75V, 1.0V, 2.0V, 3.0V, 4.0V, 5.0V, 10V, 15V, or about 20V. The electrochemical reduction system can have an operating voltage of at least about 0.1 volts (V), 0.2V, 0.3V, 0.4V, 0.5V, 0.75V, 1.0V, 2.0V, 3.0V, 4.0V, 5.0V, 10V, 15V, or about 20V or more. The electrochemical reduction system can have an operating voltage of about 20V, 15V, 10V, 5.0V, 4.0V, 3.0V, 2.0V, 1.0V, 0.75V, 0.5V, 0.4V, 0.3V, 0.2V, or about 0.1V or less.

[0057] The electrochemical reduction system can have an optimal cathode current density. In some cases, the cathode current density can determine the rate of CO or CO2 reduction at the cathode. The cathode can be characterized by an overall electrochemical efficiency. The overall electrochemical efficiency can be defined as the percentage of electrical energy that is converted to chemical energy. The cathode can have an optimal current density of about 10 milliamps per square centimeter (mA / cm 2 ), 50mA / cm 2 , 100mA / cm 2 , 150mA / cm 2 , 200mA / cm 2 , 250mA / cm 2 , 300mA / cm 2 , 350mA / cm 2 , 400mA / cm 2 , 450mA / cm 2 , 500mA / cm 2 , 600mA / cm 2 , 700mA / cm 2 , 800mA / cm 2 , 900mA / cm 2 , or about 1000mA / cm 2 The cathode can have a cathode current density of at least about 10 mA / cm 2 , 50mA / cm 2 , 100mA / cm 2 , 150mA / cm 2 , 200mA / cm 2 , 250mA / cm 2 , 300mA / cm 2 , 350mA / cm 2 , 400mA / cm 2 , 450mA / cm 2 , 500mA / cm 2 , 600mA / cm 2 , 700mA / cm 2 , 800mA / cm 2 , 900mA / cm 2 , or about 1000mA / cm 2 The cathode can have a cathode current density of about 1000 mA / cm or more. 2 , 900mA / cm 2, 800mA / cm 2 , 700mA / cm 2 , 600mA / cm 2 , 500mA / cm 2 , 450mA / cm 2 , 400mA / cm 2 , 350mA / cm 2 , 300mA / cm 2 , 250mA / cm 2 , 200mA / cm 2 , 150mA / cm 2 , 100mA / cm 2 , 50mA / cm 2 , 10mA / cm 2 The cathode current density may be:

[0058] The cathode in the electrochemical reduction system can have a total electrochemical efficiency. The cathode can have a total electrochemical efficiency of about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more. The cathode can have a total electrochemical efficiency of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more. The cathode may have an overall electrochemical efficiency of about 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or less.

[0059] The electrolyte solution can include a solution having a particular ionic strength or molarity. The electrolyte can have an ionic strength of about 0.01 moles per liter (M), 0.05M, 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, 1.0M, 1.1M, 1.2M, 1.3M, 1.4M, 1.5M, 2.0M, 2.5M, or about 3.0M. The electrolyte solution can have an ionic strength of at least about 0.01 M, 0.05 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, 1.5 M, 2.0 M, 2.5 M, or at least about 3.0 M or more. The electrolyte solution can have an ionic strength of about 3.0 M, 2.5 M, 2.0 M, 1.5 M, 1.4 M, 1.3 M, 1.2 M, 1.1 M, 1.0 M, 0.9 M, 0.8 M, 0.7 M, 0.6 M, 0.5 M, 0.4 M, 0.3 M, 0.2 M, 0.1 M, 0.05 M or less, or about 0.01 M or less. The salt in the electrolyte solution can have a molar concentration of about 0.01 moles per liter (M), 0.05 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, 1.5 M, 2.0 M, 2.5 M, or about 3.0 M. The salt in the electrolyte solution can have a molar concentration of at least about 0.01 M, 0.05 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, 1.5 M, 2.0 M, 2.5 M, or at least about 3.0 M or more. The salt in the electrolyte solution can have a molarity of about 3.0M, 2.5M, 2.0M, 1.5M, 1.4M, 1.3M, 1.2M, 1.1M, 1.0M, 0.9M, 0.8M, 0.7M, 0.6M, 0.5M, 0.4M, 0.3M, 0.2M, 0.1M, 0.05M or less, or about 0.01M or less.The salt in the electrolyte solution may have a molar concentration in the range of about 0.01M to about 0.1M, about 0.01M to about 0.2M, about 0.01M to about 0.5M, about 0.01M to about 1.0M, about 0.01M to about 3.0M, about 0.1M to about 0.2M, about 0.1M to about 0.5M, about 0.1M to about 1.0M, about 0.1M to about 3.0M, about 0.2M to about 0.5M, about 0.2M to about 1.0M, about 0.2M to about 3.0M, about 0.25M to about 0.5M, about 0.25M to about 1M, about 0.25M to about 3M, about 0.5M to about 1.0M, about 0.5M to about 3.0M, or about 1.0M to about 3.0M.

[0060] The electrolyte solution can have an optimal pH for the electrochemical reduction of CO2. The electrolyte can have a pH of about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or about 14. The electrolyte can have a pH of at least about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more. The electrolyte solution can have a pH of about 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 or less. The electrolyte solution may have a pH in the range of about 0 to about 2, about 0 to about 3, about 0 to about 4, about 0 to about 5, about 0 to about 7, about 0 to about 10, about 0 to about 14, about 2 to about 3, about 2 to about 4, about 2 to about 5, about 2 to about 7, about 2 to about 10, about 2 to about 14, about 3 to about 4, about 3 to about 5, about 3 to about 7, about 3 to about 10, about 3 to about 14, about 4 to about 5, about 4 to about 7, about 4 to about 10, about 4 to about 14, about 5 to about 7, about 5 to about 10, about 5 to about 14, about 7 to about 10, about 7 to about 14, or about 10 to about 14.

[0061] The electrolyte solution in the electrochemical reduction system can be a non-aqueous electrolyte solution. Optionally, the electrolyte solution can be an aqueous electrolyte solution. Optionally, the electrolyte solution can include an ionic liquid with a dissolved salt. The ionic liquid can include, but is not limited to, midazolium-based fluorinated anion ionic liquids, acetate, midazolium fluoroacetates, pyrrolidinium-based ionic liquids, or any combination thereof. The aqueous electrolyte solution can be water or an electrolyte dissolved in water. Optionally, the electrolyte can include an aqueous salt solution.

[0062] Described herein are various chemical products and reaction mixtures generated via electrochemical reduction of CO2 captured from an incoming air stream. Electrochemical reduction involves the application of electrical energy in the form of chemical bonds. Electrochemical reduction can produce carbon species consisting of one or more components selected from carbon monoxide, hydrocarbon gases, alkanes, alkenes, alcohols, aldehydes, organic acids, and other organic molecules of various chain lengths. The products of the described electrochemical reduction systems can be further processed into useful products such as transportation fuels and polymers.

[0063] Described herein are various chemical products and reaction mixtures produced via electrochemical reduction of CO2 derived from a gas source. The gas source can be the atmosphere. The gas source can be any CO2-containing gas stream. The chemical product can include any process stream discharged from a chemical processing system or any process stream that does not undergo further reaction processing. The reaction mixture can include any process mixture, reagent or compound within a chemical reactor, reactor system, or process stream between chemical reactors or reactor systems. The chemical products and reaction mixtures of the present invention can include organic molecules in which one or more of the constituent carbon atoms are derived from CO2. In some cases, the chemical product or reaction mixture can include only carbon atoms derived from CO2. In other cases, the chemical product can include carbon atoms derived from CO2 and carbon atoms derived from other sources (e.g., biofuels). In some cases, the chemical products of the present invention can have a unique carbon isotope signature that matches the carbon isotope signature of CO2 derived from the atmosphere. In some cases, the chemical products and reaction mixtures of the present invention can have a unique carbon isotope signature that matches the carbon isotope signature of CO2 derived from a non-atmospheric source, such as the combustion of fossil fuels. The carbon isotopic signature of a chemical product or reaction mixture is 14 C: 12 C or 13 C: 12 In some cases, the isotopic signature of a chemical product or reaction mixture can be measured as the per mille difference between the natural isotope ratio of carbon and the measured isotope ratio. 14 C, Δ 14 For C, the per mille difference between the natural and measured isotope ratios of carbon can be calculated as follows:

number

[0064] 13 C, Δ 13 For C, the per mille difference between the natural and measured isotope ratios of carbon can be calculated as follows:

number

[0065] The chemical product or reaction mixture may have a Δ 14 The chemical product or reaction mixture may have a ΔC of at least about -100‰, -10‰, 0‰, 5‰, 10‰, 20‰, 30‰, 40‰, 45‰, 50‰, or at least about 100‰ or more. 14 The chemical product or reaction mixture may have a ΔC of up to about -100‰, -10‰, 0‰, 5‰, 10‰, 20‰, 30‰, 40‰, 45‰, 50‰, or up to about 100‰ or less. 14 The chemical product or reaction mixture can have a ΔC of about -40‰, -35‰, -30‰, -28‰, -26‰, -24‰, -22‰, -20‰, -15‰, -10‰, -8‰, or about -5‰. 13 The chemical product or reaction mixture may have a ΔC of at least about -40‰, -35‰, -30‰, -28‰, -26‰, -24‰, -22‰, -20‰, -15‰, -10‰, -8‰, or at least about -5‰ or more. 13 The chemical product or reaction mixture may have a C of up to about -40‰, -35‰, -30‰, -28‰, -26‰, -24‰, -22‰, -20‰, -15‰, -10‰, -8‰, or up to about -5‰ or less Δ 13 In this specification, ΔC is greater than -25‰. 13 In one embodiment, a product or reaction mixture is provided that includes a composition having Δ 13 C can correspond to the value of the environmental temperature at which CO2 is captured (e.g., -8‰). 13 C may differ from the isotopic signature of products derived from, for example, fossil fuels or biological (e.g., plant-based) fuels. 13 C levels are lower than atmospheric levels, Δ 13 C can be -25‰. In another example, for fossil fuels (e.g., from petroleum, coal, etc.), Δ 13C can be even lower than plant-based fuels, i.e., less than -25‰. Alternatively, or in addition, the products or reaction mixtures described herein can include compositions having no detectable sulfur, metals, and / or aromatics. Detectable levels, in one example, can refer to compositions up to an order of magnitude of 1%, 0.1%, 0.01%, 0.001%, 0.0001%, 0.00001% or less by weight. The products or reaction mixtures of the present disclosure can include hydrocarbon mixtures including C1+ products.

[0066] The chemical products or reaction mixtures of the present invention may include gaseous, liquid or solid substances. The chemical products and reaction mixtures of the present invention may include one or more organic compounds. The chemical products and reaction mixtures may be miscible or immiscible with water. The chemical products and reaction mixtures may be polar or non-polar. The chemical products and reaction mixtures may be acidic, basic or neutral. The organic compounds may include alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, cycloalkynes, substituted alkanes, substituted alkenes, substituted alkynes, alcohols, esters, carboxylic acids, ethers, amines, amides, aromatics, heteroaromatics, sulfides, sulfones, sulfates, thiols, aldehydes, ketones, amides and halogenated compounds. The chemical products and reaction mixtures may include branched or linear compounds. The chemical products and reaction mixtures can include oxygen, methane, ethane, ethylene, propane, butane, hexane, octane, decane, carbon monoxide, methanol, ethanol, propanol, butanol, hexanol, octanol, and formates. The chemical products and reaction mixtures can include organometallic compounds. The chemical products and reaction mixtures of the present disclosure can include compounds intended for consumer or industrial use, such as fuels, solvents, additives, polymers, food additives, dietary supplements, pharmaceuticals, fertilizers, pesticides, coatings, lubricants, and building materials. The chemical products and reaction mixtures of the present disclosure can include precursors, components, substituents, or substrates of products produced by subsequent processing.

[0067] The organic compounds of the present disclosure can contain one or more carbon atoms. In some cases, the organic compounds can contain about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, or about 70 carbon atoms. In some cases, the organic compounds can contain at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, or about 70 or more carbon atoms. In some cases, the organic compound can contain up to about 70, 65, 60, 55, 50, 45, 40, 35, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 or less carbon atoms. The organic compounds of the present disclosure can contain one or more carbon atoms derived from CO or CO2. In some cases, the organic compound can include about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, or about 70 carbon atoms derived from CO or CO2. In some cases, the organic compound can contain at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, or about 70 or more carbon atoms derived from CO or CO2. In some cases, the organic compound can contain about 70 or less, 65, 60, 55, 50, 45, 40, 35, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 or less carbon atoms derived from CO or CO2.

[0068] The chemical product or reaction mixture of the present disclosure can include multiple chemical species. The chemical product or reaction mixture can be a mixture of about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or about 100 detectable chemical compounds. The chemical product or reaction mixture can be a mixture of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or about 100 or more detectable chemical compounds. The chemical product or reaction mixture can be a mixture of about 100 or less, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, or about 3 or less detectable chemical compounds.

[0069] A chemical product or reaction mixture of the present disclosure can include a particular compound at a particular weight percent or molar percent of the total chemical product or reaction mixture. For example, a particular chemical product can include at least about 50% ethanol by weight. In another example, a particular chemical product can include about 1% water or less by weight. In some cases, at least about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more of a chemical product or reaction mixture can be a particular chemical compound on a weight or molar basis. In some cases, about 99% or less, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or about 10% or less of the chemical product or reaction mixture on a weight or molar basis is a particular chemical compound.

[0070] The chemical products or reaction mixtures of the present disclosure can include compounds within a particular range of molecular weights or carbon numbers. In some cases, at least about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more of the chemical product or reaction mixture can include compounds within a particular molecular weight or carbon number range. In some cases, about 99% or less, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or about 10% or less of a chemical product or reaction mixture can comprise compounds within a particular molecular weight or carbon number range.The chemical product or reaction mixture may be from about 15 g / mol to about 30 g / mol, from about 15 g / mol to about 60 g / mol, from about 15 g / mol to about 100 g / mol, from about 15 g / mol to about 200 g / mol, from about 15 g / mol to about 400 g / mol, from about 15 g / mol to about 600 g / mol, from about 15 g / mol to about 1000 g / mol, from about 30 g / mol to about 6 ... ol~about 100g / mol, about 30g / mol~about 200g / mol, about 30g / mol~about 400g / mol, about 30g / mol~about 600g / mol, about 30g / mol~about 1000 g / mol, about 60g / mol to about 100g / mol, about 60g / mol to about 200g / mol, about 60g / mol to about 400g / mol, about 60g / mol to about 600g / mol, about 60 g / mol~about 1000g / mol, about 100g / mol~about 200g / mol, about 100g / mol~about 400g / mol, about 100g / mol~about 600g / mol, about 100g / m ol~about 1000g / mol, about 200g / mol~about 400g / mol, about 200g / mol~about 600g / mol, about 200g / mol~about 1000g / mol, about 400g / mol~ It can include compounds within a molecular weight range of about 600 g / mol, about 30 g / mol to about 1000 g / mol, about 30 g / mol to about 100 g / mol, about 30 g / mol to about 200 g / mol, about 30 g / mol to about 400 g / mol, about 30 g / mol to about 600 g / mol, about 400 g / mol to about 1000 g / mol, or about 600 g / mol to about 1000 g / mol.The chemical product or reaction mixture can contain compounds within a carbon number range of about C1 to about C2, about C1 to about C3, about C1 to about C4, about C1 to about C5, about C1 to about C6, about C1 to about C8, about C1 to about C10, about C1 to about C20, about C1 to about C30, about C1 to about C40, about C2 to about C3, about C2 to about C4, about C2 to about C5, about C2 to about C6, about C2 to about C8, about C2 to about C10, about C2 to about C20, about C2 to about C30, about C2 to about C40, about C3 to about C4, about C3 to about C5, about C3 to about C6, about C3 to about C8, about C3 to about C10, about C3 to about C20, about C3 to about C30, about C3 to about C40, about C4 to about C5, about C4 to about C6, about C4 to about C8, about C4 to about C10, about C4 to about C20, about C4 to about C30, about C4 to about C40, about C5 to about C6, about C5 to about C8, about C5 to about C10, about C5 to about C20, about C5 to about C30, about C5 to about C40, about C6 to about C8, about C6 to about C10, about C6 to about C20, about C6 to about C30, about C6 to about C40, about C8 to about C10, about C8 to about C20, about C8 to about C30, about C8 to about C40, about C10 to about C20, about C10 to about C30, about C10 to about C40, about C20 to about C30, about C20 to about C40, or about C30 to about C40.

[0071] The chemical product or reaction mixture of the present disclosure may include one or more impurities. The impurities may originate from reactant streams, reactor contaminants, decomposition products of organic compounds produced, catalyst compounds, or side reactions within the electrochemical reduction system or other chemical conversion systems described herein. The chemical product or reaction mixture may include one or more organic impurities, such as formates or high molecular weight alcohols. The chemical product or reaction mixture may include carbon or non-carbon nanomaterial impurities. The chemical product or reaction mixture may include one or more inorganic impurities originating from sources such as decomposition of catalysts or leaching and corrosion of process equipment. Inorganic impurities may include sodium, magnesium, potassium, calcium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, silicon, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tantalum, tungsten, osmium, platinum, gold, mercury, and lead. The inorganic impurities may be present in an oxidized or reduced oxidation state. Inorganic impurities may be present in the form of organometallic complexes. Impurities in chemical products or reaction mixtures may be detectable by any common analytical technique, such as gas or liquid chromatography, mass spectrometry, IR or UV-Vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, or other methods. One or more impurities may be detectable in an amount of at least about 1 ppb, 5 ppb, 10 ppb, 50 ppb, 100 ppb, 250 ppb, 500 ppb, 750 ppb, 1 ppm, 5 ppm, 10 ppm, 50 ppm, 100 ppm, or more. One or more impurities may be detectable in an amount of about 100 ppm or less, 50 ppm, 10 ppm, 5 ppm, 1 ppm, 750 ppb, 500 ppb, 250 ppb, 100 ppb, 50 ppb, 10 ppb, 5 ppb, or about 1 ppb or less or less.

[0072] The chemical product may have a particular level of purity. In some cases, the chemical product may have sufficient purity to achieve a particular grade or standard. The chemical product may be ACS grade, reagent grade, USP grade, NF grade, laboratory grade, refined grade, or technical grade. The chemical product may have a purity above the azeotropic composition, for example, >95% ethanol. The gaseous chemical product of the present invention may have a purity grade of about N1.0, N2.0, N3.0, N4.0, N5.0, N6.0, or higher. The chemical product may achieve a purity level according to a prescribed international standard, for example, the ASTM D-1152 / 97 standard for methanol purity.

[0073] In some cases, the chemical product or reaction mixture obtained from the electrochemical reduction system may not have detectable amounts of certain impurities. In some cases, the chemical product or reaction mixture may not have detectable amounts of biomolecules or derivatives thereof. The chemical product or reaction mixture may not contain detectable amounts of lipids, sugars, proteins, nucleic acids, amino acids, spores, bacteria, viruses, protozoa, fungi, animal or plant cells, or any components thereof.

[0074] The electrochemical reduction system can capture CO2 and convert it to reduced carbon products. In one example, the system can be introduced into an air stream containing CO2. In some examples, the incoming air stream containing CO2 can interact with an electrolyte solution. In some embodiments, the interaction of the incoming air stream containing CO2 with the electrolyte solution occurs in a contactor. In some cases, the interaction of the incoming air stream containing CO2 with the electrolyte solution can result in capture of CO2 in the electrolyte. In some examples, capture of CO2 can occur as adsorption of CO2 to the electrolyte or absorption of CO2 into the electrolyte. In some examples, capture of CO2 can occur as a physical interaction (e.g., electrostatic interaction, adsorption, absorption) between the CO2 and the electrolyte. In some examples, capture of CO2 can occur as a chemical interaction between the CO2 and the electrolyte. In some examples, the captured CO2 molecule can be in the form of bicarbonate ions. For example, the air stream containing CO2 can interact with water to produce carbonic acid, which further dissociates in water to produce bicarbonate ions and hydronium ions (e.g., H + , H3O + , or proton). [ka]

[0075] In such an example, the pH of the electrolyte solution may decrease (e.g., increase acidity) due to the generation of bicarbonate and hydronium ions. In some embodiments, CO2 may be transported to a separate chamber or compartment while being captured in the electrolyte solution. In some embodiments, CO2 is reduced in this separate chamber. In some examples, the captured CO2 molecules (e.g., bicarbonate ions) may be directly reduced in the presence of a voltage to generate a reduced carbon product. In some cases, the captured CO2 may not require release (e.g., desorption) from the captured CO2 material before being reduced to a reduced carbon product. For example, the captured CO2 may be bicarbonate ions, which may be directly reduced to a reduced carbon product without the need for an additional step that requires desorption of CO2 from the bicarbonate ions. In one example, captured CO2 in the form of bicarbonate may be reduced to ethanol in the presence of a voltage according to the following reaction scheme: [ka]

[0076] The reduced carbon products may include alcohols, aldehydes, alkenes, alkanes, acids, or combinations thereof. The alcohols may include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tertbutanol, pentanol, isopentanol, hexanol, isohexanol, or any other straight-chain or branched alcohol. The aldehydes may include methanal, ethanal, propanal, isopropanal, butanal, isobutanal, or any other straight-chain or branched aldehyde. The alkene or alkane may be a straight-chain or branched alkene or alkane. In some embodiments, the alkene or alkane includes an alkyl chain that is at least 1 carbon, 2 carbons, 3 carbons, 4 carbons, 5 carbons, 6 carbons, 7 carbons, or more in length. In some embodiments, the reduced carbon products may be further reduced in the presence of a voltage and / or an electrolyte to form additional reduced carbon products (e.g., alcohols or aldehydes). For example, an alcohol or aldehyde can be reduced in the presence of a voltage to produce a longer chain reduced carbon product. In some embodiments, the conversion of CO2 to ethanol and hydroxide ions occurs according to the following chemical reaction, where CO2 and HCO3 - is in equilibrium in solution. [ka]

[0077] In some examples, the production of hydroxide ions increases the pH of the solution (e.g., becomes less acidic or more basic). In some embodiments, application of a voltage to the captured CO2 solution can convert at least about 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, 99%, or 100% of the captured CO2 solution to reduced carbon products.

[0078] In some examples, the reduced carbon product may be separated from a mixture that includes the reduced carbon product, captured CO2, electrolyte, carbon dioxide, hydroxide ions, or hydronium ions. In some examples, the reduced carbon product is separated from the mixture by passing through a membrane. In some examples, separating the reduced carbon product from the mixture by passing from a first side of the membrane to a second side of the membrane relatively increases the pH of the solution on the first side of the membrane (e.g., increases the relative concentration of hydroxide ions).

[0079] In some examples, the electrolyte solution can be regenerated for further capture and reduction cycles. For example, hydroxide ions produced as a by-product of the reduction of captured CO can interact with bicarbonate ions (e.g., bicarbonate ions that were not converted to reduced carbon products) to produce carbonate ions and water according to the following reaction scheme: [ka]

[0080] In some embodiments, the water generated by the interaction of bicarbonate ions and hydroxide ions can capture additional CO2 from the air stream. Thus, the ability of the electrolyte solution (e.g., water) to capture CO2 can be regenerated. In some examples, the hydroxide ions generated by the reduction of CO2 can diffuse through the anion exchange layer of the membrane stack and migrate toward the anode. In such examples, the pH of the electrolyte solution in contact with the anode can increase. In some embodiments, the increase in pH of the electrolyte solution promotes further capture of CO2. In some examples, the regenerated electrolyte solution can be recycled and reused to capture additional CO2 from the air stream.

[0081] The incoming air stream can contact the electrolyte solution. This contact can be facilitated by a contactor. The electrochemical reduction system can include one or more contactor units. The contactor can include any unit operation or separation unit that selectively separates one or more chemical species from the feed stream. In some cases, the contactor can include a gas adsorption column. In other examples, the contactor can include packing to increase the surface area of ​​the solution and a fan to increase the passage of gas at the liquid interface. In other examples, the contactor can consist of or include a membrane. Such contactors can share design features with cooling towers. In some embodiments, a compartment or chamber of the system can include a contactor. In some examples, a first compartment or chamber of the system can include a contactor.

[0082] The electrochemical reduction system may have one or more ion exchange membranes. The ion exchange membrane may be a cation exchange membrane, an anion exchange membrane, or a bipolar membrane. The ion exchange membrane may be in operative contact with the cathode, the anode, or both the cathode and the anode. In some cases, the electrochemical reduction system may not have an ion exchange membrane. In some cases, the ion exchange membrane may be configured to minimize the distance between the anode and the cathode. The ion exchange membrane may have a thickness of about 1 micrometer (μm), 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 125 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 750 μm, 1 mm, or more than 1 mm. The ion exchange membrane may have a thickness of at least about 1 μm, 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 125 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 750 μm, 1 millimeter (mm), or more. The ion exchange membrane may have a thickness of about 1 mm or less, 750 μm, 500 μm, 400 μm, 300 μm, 250 μm, 200 μm, 150 μm, 125 μm, 100 μm, 50 μm, 25 μm, 10 μm, 5 μm, 1 μm, or less.

[0083] The bipolar membrane may be a bipolar membrane stack. The bipolar membrane stack may include a cation exchange layer (e.g., a membrane) and an anion exchange layer (e.g., a layer). Optionally, the bipolar membrane stack may further include a mechanical reinforcement between the cation exchange layer and the anion exchange layer. The bipolar membrane stack may be configured such that the cation exchange layer is disposed toward the cathode and the anion exchange layer is disposed toward the anode. Optionally, a directional voltage may be applied to promote dissociation or regeneration of the electrolyte. Optionally, a reverse voltage bias may be applied, and the electrolyte may dissociate into cations and anions when passing through the bipolar membrane under the applied voltage. For example, water may dissociate into hydroxide ions and hydronium ions when passing through the membrane under the applied voltage. In such an example, the hydronium ions may diffuse through the cation exchange layer toward the cathode and the hydroxide ions may diffuse through the anion exchange layer toward the anode. Optionally, a forward voltage bias can be applied and hydroxide and hydronium ions can diffuse through the cation and anion exchange layers toward the interface of the two layers to produce water. Optionally, the produced water can diffuse out of the cation exchange layer, the anion exchange layer, or a combination thereof.

[0084] In some embodiments, the membrane stack may be a bipolar membrane stack. In some examples, the bipolar membrane may dissociate water into hydroxide ions and hydronium ions at or near the interface between the anion exchange layer and the cation exchange layer, with the hydroxide ions migrating toward and through the anion exchange layer and the hydronium ions migrating toward and through the cation exchange layer. In some embodiments, the membrane stack may include an anion exchange layer separator. In such embodiments, the hydroxide ions may migrate toward and through the anion exchange layer and toward the anode. In some embodiments, the membrane stack may include a cation exchange layer separator. In such examples, the hydronium ions may migrate from the anode side to the cathode side of the compartment.

[0085] The contactor may include a cation exchange membrane stack. The contactor may include a bipolar membrane that selectively allows transport of carbon-containing species into the electrolyte. The contactor may also be used to regulate the pH of the electrolyte stream.

[0086] Optionally, the contactor may include an extractor. In another example, the extractor may include a membrane separator. Optionally, the extractor may include a microstructured or nanostructured membrane. Optionally, the contactor may extract one or more chemical species from the feed stream. Optionally, the contactor may extract CO2 from the feed stream. Optionally, the contactor may separate CO or CO2 from the feed stream and dissolve the CO or CO2 in an electrolyte solution. Optionally, the feed stream may be air. Optionally, the feed stream may be filtered before use. Such filtration may optionally remove particulate material and / or volatile organic material and / or various types of undesirable material. The capture of CO or CO2 in the gas contactor may be facilitated by the presence of hydroxide ions generated in the electrochemical reduction system. The contactor may be a membrane contactor, a random or structured gas-liquid contacting packing such as a film fill or splash packing, a packed falling film device such as a cooling tower, a fluidized bed, a shower of liquid in contact with a gas, or the like. In some embodiments, the contactor can be made of a nanostructured carbon material, such as the carbon nanotube film shown in Figure 9. In some embodiments, the contactor 903 can be the carbon nanotube film 901 shown in Figure 9, can have nanotubes 1002 functioning as pores as shown in Figure 10, and can have the openings of the nanotubes 1102 functionalized with adsorptive functional groups 1104, such as amines, as shown in Figure 11.

[0087] The present disclosure can provide reactors and separation systems that include microstructured or nanostructured membranes. The microstructured or nanostructured membranes can be utilized to effect selective separation of one or more chemical species from a mixture that includes multiple chemical species. The microstructured or nanostructured membranes can also provide additional applications in chemical processing systems, including the physical separation of product streams and the electrical cathode or anode components of electrochemical systems.

[0088] The electrochemical conversion system may include one or more unit operations for separation. Separation unit operations may include distillation columns, reactive distillation columns, gas absorption columns, stripping columns, additional catalysis operations using, for example, catalyst packed columns, flash tanks, humidifiers, percolation units, liquid-liquid extraction units, dryers, adsorption systems, ion exchange columns, membrane separation units, filtration units, precipitation units, and crystallization units. The chemical conversion system may include one or more unit operations for heat transfer. Heat transfer unit operations may include mantle heaters, cartridge heaters, tape heaters, pad heaters, resistance heaters, radiant heaters, fan heaters, shell-and-tube heat exchangers, plate-type heat exchangers, expanded surface heat exchangers, scraped surface heat exchangers, condensers, vaporizers, and evaporators. The chemical conversion system may include one or more unit operations for fluid movement. Fluid movement devices may include piping, tubing, fittings, valves, pumps, fans, blowers, compressors, stirrers, agitators, and blenders. The pumping equipment may be operated at pressures above atmospheric pressure or may be used to draw a vacuum. The chemical conversion system may comprise one or more chemical reaction units apart from the electrochemical reduction reactor. The chemical reaction units may include plug flow reactors, continuous stirred tank reactors, packed bed columns, fluidized bed reactors and batch reactors. The chemical reactors may be utilized for a variety of upgrading and conversions including dehydrogenation, hydrogenation, cracking, dehydration, decarbonation, carboxylation, amination, deamination, alkylation, dealkylation, oxidation, reduction, polymerization and depolymerization.

[0089] An electrochemical conversion system including one or more microstructured or nanostructured membranes can reduce or eliminate the energy consumption associated with one or more unit operations. For example, a gas separator including one or more microstructured or nanostructured membranes can eliminate the need for a distillation column or a separate adsorption system to separate CO or CO2 from air. In some cases, the use of a unit operation including a microstructured or nanostructured membrane can eliminate one or more pumps, compressors, heat exchangers, separators, or reactors from an electrochemical reduction system. The use of one or more microstructured or nanostructured membranes can reduce the energy consumption of a process step or component by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or more.

[0090] A microstructured or nanostructured membrane can include one or more microscale or nanoscale material features (e.g., positive features such as microscale or nanoscale structures, and / or negative features such as microscale and nanoscale pores or microscale and nanoscale recesses). In some cases, the membrane can include carbon nanotubes, carbon nanospheres, carbon nano-onions, graphene-like materials, or pyrolyzed porous carbon materials (see Figures 9 and 10). The membrane can include microstructured or nanostructured materials synthesized from non-carbon materials. The membrane can include carbon nanomaterials doped with other elements such as nitrogen, sulfur, and boron. The microstructured or nanostructured materials can be embedded, fixed, or otherwise bonded to one or more other substrates or materials to construct the membrane. The microstructured or nanostructured materials embedded in the substrate or material can create pores in the structured membrane. The pores can allow the selective passage of certain chemical species. The other substrates or materials in the membrane can be selected for material properties including stiffness, strength, and / or electrical conductivity. Other substrates or materials within the microstructured or nanostructured membrane can include polymers, such as polysulfones, metals, and ceramics. Microscale or nanoscale features can have a maximum dimension of at least about 0.4 nanometers (nm), 0.6 nm, 0.8 nm, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.5 nm, 3.0 nm, 3.5 nm, 4.0 nm, 4.5 nm, 5.0 nm, 5.5 nm, 6.0 nm, 6.5 nm, 7.0 nm, 7.5 nm, 8.0 nm, 8.5 nm, 9.0 nm, 9.5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 micrometer, 10 micrometers, 100 micrometers or more.In some cases, the maximum dimension can be up to about 100 micrometers, 10 micrometers, 1 micrometer, 900 nm, 800 nm, 700 nm. 600 nm, 500 nm, 400 nm, 300 nm, 200 nm, 100 nm, 90 nm, 80 nm, 70 nm, 60 nm, 50 nm, 40 nm, 30 nm, 20 nm, 10 nm, 9.5 nm, 9.0 nm, 8.5 nm, 8 nm, 7.5 nm, 7.0 nm, 6.5 nm, 6.0 nm, 5.5 nm, 5.0 nm, 4.5 nm, 4.0 nm, 3.5 nm, 3.0 nm, 2.5 nm, 2.0 nm, 1.8 nm, 1.6 nm, 1.4 nm, 1.2 nm, 1.0 nm, 0.8 nm, 0.6 nm, or 0.4 nm or less.

[0091] A microstructured or nanostructured membrane may have a particular shape and / or structure depending on its application. In some cases, the membrane may have a cylindrical structure, for example having a hollow fiber membrane format (see Figures 9 and 10), or may have a substantially flat sheet structure. The membrane may partially or completely enclose a volume or void space. The surface area of ​​the membrane disposed toward the enclosed or void space may be defined as the luminal side of the membrane. In some cases, mass transfer across the membrane may be driven by chemical potential, pressure difference, and / or temperature difference between the luminal and abluminal sides of the membrane. The membrane may further have additional structures, such as a frame or fittings that secure the membrane to other parts of the described system.

[0092] A microstructured or nanostructured membrane may be composed of micro- or nano-materials embedded to create pores in the membrane. The micro- or nano-material may be selected based on the characteristic pore size it can create. Without wishing to be bound by theory, a pore may be defined as a void space or volume in a solid material through which liquid or gas molecules may flow or diffuse. A micro- or nano-material may have a characteristic length scale, such as a diameter, (average) pore size, or layer spacing, sufficient to allow chemical species to pass through the void space in the material. In some cases, the characteristic length may be at least about 0.4 nanometers (nm), 0.6 nm, 0.8 nm, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.5 nm, 3.0 nm, 4.0 nm, 5.0 nm, or more. In some cases, the characteristic length may be about 5.0 nm or less, 4.0 nm, 3.0 nm, 2.5 nm, 2.0 nm, 1.8 nm, 1.6 nm, 1.4 nm, 1.2 nm, 1.0 nm, 0.8 nm, 0.6 nm, or about 0.4 nm or less. The pore may have a diameter greater than the length. The pore may have a length greater than the diameter. The pore may have an aspect ratio of about 1:10, 1:5, 1:2, 1:1, 2:1, 5:1, 10:1, 100:1, or about 1000:1. The pore may have an aspect ratio of at least about 1:10, 1:5, 1:2, 1:1, 2:1, 5:1, 10:1, 100:1, or about 1000:1. The pores may have an aspect ratio of about 1000:1 or less, 100:1, 10:1, 5:1, 2:1, 1:1, 1:2, 1:5, or about 1:10 or less. The pores may comprise substantially straight paths, such as carbon nanotubes, or spaces between layers of horizontal graphene-like materials. The pores may have tilted, oblique, or tortuous paths in some materials, such as mesoporous or nanoporous carbons.

[0093] The membrane can include materials having a characterized porous structure. The materials can include nanopores, mesopores, and micropores. In some cases, the nanopores can be characterized as having an average diameter of about 2 nm or less. In some cases, the mesopores can be characterized as having an average pore size of about 2 nm to about 20 nm. In some cases, the micropores can be characterized as having an average pore size of about 20 nm or more. The membrane can include structures having pore sizes across a range of pore sizes (e.g., nanopores and mesopores). The membrane can include structures having pore sizes from within a particular classification of pore sizes (e.g., only mesopores). The membrane can include pores (e.g., micropores or nanopores) having an average diameter of at least about 0.5 nm, 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 100 nm, 250 nm, 500 nm, 1 micron (μm), or at least about 5 μm or more. The membrane can include pores having an average diameter of about 5 μm or less, 1 μm, 500 nm, 250 nm, 100 nm, 50 nm, 40 nm, 30 nm, 20 nm, 15 nm, 10 nm, 5 nm, 1 nm, 0.5 nm or less.

[0094] Membranes including micro- or nano-structured materials may allow mass transport of one or more chemical species across the membrane. Membranes including micro- or nano-structured materials may be selective for certain species. In some cases, membranes including micro- or nano-structured materials may selectively transfer CO2 from a gas stream. In some cases, membranes including micro- or nano-structured materials may selectively transfer gaseous ethylene or ethanol from a gas mixture. In some cases, membranes including micro- or nano-structured materials may selectively transfer hydrocarbons from an aqueous liquid mixture. Membranes including micro- or nano-structured materials may transfer certain chemical species by diffusion or convection mass transport. In some cases, mass transfer may be enhanced by the application of an external force or field. In certain cases, mass transfer may be facilitated or enhanced by the application of a magnetic or electric field. In other cases, mass transfer may be facilitated by a pressure gradient (e.g., drawing a vacuum against one side of the membrane). In some cases, the selectivity of the membrane may be reversed by reversing the applied field or force. In other cases, the membrane may have unidirectional or unaltered mass transfer selectivity. A voltage bias may be present as the electrochemical reduction process is carried out. The voltage bias may be used to change the selectivity of the membrane, for example, from alcohol selectivity to water selectivity. When an electric field is present, a magnetic field may also be present, which can be used to affect the concentration of ions. The magnetic field may be influenced to favorably increase the availability of reactants or intermediates at the catalyst surface.

[0095] The microstructured or nanostructured membrane may have an optimal or preferred operating temperature and pressure. In some cases, the system with the microstructured or nanostructured membrane may be operated at ambient pressure or temperature. In some cases, the system with the microstructured or nanostructured membrane may be operated at high pressure or under vacuum or reduced pressure. A pressure gradient may be used to facilitate mass transfer across the membrane system. The microstructured or nanostructured membrane may be utilized in a system having an operating temperature of about -30°C, -20°C, -10°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, or about 80°C. Microstructured or nanostructured films may be utilized in systems having operating temperatures of at least about -30°C, -20°C, -10°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, or greater than about 80°C. Microstructured or nanostructured films may be utilized in systems having operating temperatures of about 80°C or less, 75°C, 70°C, 65°C, 60°C, 55°C, 50°C, 45°C, 40°C, 35°C, 30°C, 25°C, 20°C, 15°C, 10°C, 5°C, 0°C, -5°C, -10°C, -20°C, or less than about -30°C.

[0096] The microstructured or nanostructured membranes may be utilized in systems having operating pressures of about 0 bar, 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, 7 bar, 8 bar, 9 bar, 10 bar, 15 bar, 20 bar, 30 bar, 40 bar, 50 bar or more. The microstructured or nanostructured membranes may be utilized in systems having operating pressures of at least about 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, 7 bar, 8 bar, 9 bar, 10 bar, 15 bar, 20 bar, 30 bar, 40 bar, 50 bar or more. The microstructured or nanostructured membranes may be utilized in systems having operating pressures of about 50 bar or less, 40 bar, 30 bar, 20 bar, 15 bar, 10 bar, 9 bar, 8 bar, 7 bar, 6 bar, 5 bar, 4 bar, 3 bar, 2 bar, 1 bar or less.

[0097] The micro- or nanostructured membrane may be capable of allowing a specific flow of CO2 across the membrane. The flow of CO2 may be driven by a pressure gradient across the membrane. In some cases, the pressure gradient may be driven by a gas flow containing CO2 at a pressure higher than ambient pressure. In other cases, the pressure gradient may be present by drawing a vacuum against one side of the membrane, e.g., the luminal side. Micro- or nanostructured membranes may be capable of allowing a specific flow of CO2 across the membrane, e.g., about 0.1 kilograms of gas per meter of membrane. 2 / hour(kg / m 2 / hour), 0.5kg / m 2 / hour, 1kg / m 2 / hour, 2kg / m 2 / hour, 3kg / m 2 / hour, 4kg / m 2 / hour, 5kg / m 2 / hour, 6kg / m 2 / hour, 7kg / m 2 / hour, 8kg / m 2 / hour, 9kg / m 2 / hour, or about 10 kg / m 2 The microstructured or nanostructured membrane may be capable of a CO flux of at least about 0.1 kg / m 2 / hour, 0.5kg / m 2 / hour, 1kg / m 2 / hour, 2kg / m 2 / hour, 3kg / m 2 / hour, 4kg / m 2 / hour, 5kg / m 2 / hour, 6kg / m 2 / hour, 7kg / m 2 / hour, 8kg / m 2 / hour, 9kg / m 2 / hour, or at least about 10 kg / m 2 A microstructured or nanostructured membrane can allow for a CO flux of about 10 kg / m 2 / hour or less, 9kg / m 2 / hour, 8kg / m 2 / hour, 7kg / m 2 / hour, 6kg / m 2 / hour, 5kg / m 2 / hour, 4kg / m 2 / hour, 3kg / m 2 / hour, 2kg / m 2 / hour, 1kg / m2 / hour, 0.5kg / m 2 / hour, or approximately 0.1 kg / m 2 This may allow for CO2 fluxes of up to 1 / hr.

[0098] The micro- or nano-structured membrane may be capable of allowing a specific flow of the hydrocarbon across the membrane. The flow of the hydrocarbon may be driven by a pressure gradient across the membrane. In some cases, the pressure gradient may be driven by a gas or liquid flow containing the hydrocarbon at a pressure higher than the ambient pressure. In other cases, the pressure gradient may be present by drawing a vacuum against one side of the membrane, e.g., the luminal side. The micro- or nano-structured membrane may be capable of allowing a specific flow of the hydrocarbon across the membrane, e.g., about 0.1 kilograms of hydrocarbon per meter of membrane. 2 / hour(kg / m 2 / hour), 0.5kg / m 2 / hour, 1kg / m 2 / hour, 2kg / m 2 / hour, 3kg / m 2 / hour, 4kg / m 2 / hour, 5kg / m 2 / hour, 6kg / m 2 / hour, 7kg / m 2 / hour, 8kg / m 2 / hour, 9kg / m 2 / hour, or about 10 kg / m 2 The microstructured or nanostructured membrane may be capable of a hydrocarbon flow of at least about 0.1 kilogram kg / m 2 / hour, 0.5kg / m 2 / hour, 1kg / m 2 / hour, 2kg / m 2 / hour, 3kg / m 2 / hour, 4kg / m 2 / hour, 5kg / m 2 / hour, 6kg / m 2 / hour, 7kg / m 2 / hour, 8kg / m 2 / hour, 9kg / m 2 / hour, or at least about 10 kg / m 2 The microstructured or nanostructured membrane can allow for a hydrocarbon flow of about 10 kg / m 2 / hour or less, 9kg / m 2 / hour, 8kg / m 2 / hour, 7kg / m 2 / hour, 6kg / m 2 / hour, 5kg / m 2 / hour, 4kg / m 2 / hour, 3kg / m 2 / hour, 2kg / m 2 / hour, 1kg / m 2 / hour, 0.5kg / m 2 / hour, or approximately 0.1 kg / m 2 This may allow for hydrocarbon flows of up to 1 / hour.

[0099] A membrane with improved selectivity for one or more chemical species may improve the chemical conversion rate or phase equilibrium of a conversion system. Without wishing to be bound by theory, selective enrichment of one or more chemical species within the void or pore space of the microstructured or nanostructured components of the membrane may increase the volume concentration of one or more chemical species within the void or pore space. In some cases, an improvement in the kinetic rate or a change in phase equilibrium of a particular chemical reaction may be promoted by one or more chemical species having a higher volume concentration within the membrane than may be predicted by the bulk phase concentrations on either side of the membrane. In certain cases, selective mass transfer of one or more chemical species through the membrane may increase the concentration of one or more chemical species at a boundary layer adjacent the surface of the membrane. An increase in the boundary layer concentration of one or more chemical species may increase the availability of one or more chemical species to a catalyst deposited on the surface of the membrane. In other cases, a material sufficient to capture CO2 with affinity for the target chemical species may be part of the membrane surface or pore inlet, and increasing the concentration of the target chemical species, e.g., amines, at the surface may promote selective transport. In other cases, a catalyst may be deposited within the void or pore space of a microstructured or nanostructured material within the membrane, allowing for enhanced mass transfer of one or more chemical species directly to the catalyst via bulk flow.

[0100] The mass transfer selectivity of the membrane for one or more chemical species may cause a measurable increase in the reaction rate of one or more chemical reactions in a chemical conversion system comprising such membrane. In some cases, the reaction rate of one or more chemical reactions may increase by at least about 5%, 10%, 20%, 30%, 40%, 50%, 75%, 100%, 150%, 200%, 500%, or about 1000% or more. In some cases, the reaction rate of one or more chemical reactions may be higher than would be predicted by the use of measured reactant concentrations due to other synergistic effects such as electric field enhancement of catalytic activity. In some cases, the mass transfer selectivity of the membrane for one or more chemical species may cause a measurable decrease in the reaction rate of one or more chemically undesirable reactions (e.g., side reactions, decomposition reactions) in a chemical conversion system comprising such membrane. In some cases, the reaction rate of one or more undesired chemical reactions may be reduced by at least about 5%, 10%, 20%, 30%, 40%, 50%, 75%, 100%, 150%, 200%, 500%, or about 1000% or more.

[0101] A membrane comprising a microstructured or nanostructured material may further comprise one or more catalytic materials. The catalytic material may be attached, bonded, deposited or functionalized to the surface of the microstructured or nanostructured material. In some cases, the catalyst may be disposed on the surface of the membrane. The catalyst may be localized in a specific region of the membrane or on a specific region of the microstructured or nanostructured material to control where the catalyzed chemical reaction may occur. The catalyst may be disposed within the pores or pore-like structures of the membrane. The chemical reaction catalyzed by the catalyst may occur on a specific region of the membrane or within the pore or pore-like spaces of the membrane. The catalyst may comprise metal atoms, metal complexes or metal particles. The catalyst may include metals such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, silicon, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tantalum, tungsten, osmium, platinum, gold, mercury, or lead. In some cases, doped carbon nanomaterials may include the catalyst. In certain cases, N-doped carbon nanotubes may include the catalyst. In other cases, carbon nanotubes electrodeposited with platinum, nickel, or copper nanoparticles may include the catalyst (see FIG. 11). The membrane may include multiple catalysts. In some cases, one or more catalysts may be deposited on one or more regions or surfaces of the membrane, and one or more different catalysts may be deposited on one or more different regions or surfaces of the membrane. The membrane may catalyze one or more chemical reactions when mass transfer occurs in a particular direction across the membrane, and one or more different chemical reactions when mass transfer occurs in different directions across the membrane.

[0102] Electrochemical reduction processes utilizing microstructured or nanostructured catalyst membranes may utilize methods or components to minimize catalyst poisoning. Catalyst-containing microstructured or nanostructured membranes may be refreshed or regenerated to mitigate the effects of catalyst poisoning and deposition of other undesirable species. In some cases, the membrane may be removed from the electrochemical reduction system for catalyst regeneration. In other cases, the membrane may be flushed with acid to dissolve or remove the catalyst particles, followed by deposition of new catalyst particles on the membrane or nanoparticle surface.

[0103] Membranes including microstructured or nanostructured materials may have enhanced electrical properties. In some embodiments, the membrane may be conductive due to the electrical properties of the microstructured or nanostructured materials. In some cases, the membrane may be semiconducting (e.g., carbon nanotubes of a particular chirality). The membrane may be configured to function as an electrode in an electrochemical system. The membrane may be capable of transmitting an electric current to one or more catalysts bound thereto. The electric current may enhance the reactivity of the catalyst for a particular catalytic chemical reaction. In some cases, the selective mass transfer of certain chemical species across the microstructured or nanostructured membrane may increase the current density achieved at the membrane electrode.

[0104] Membranes comprising microstructured or nanostructured materials may be utilized for a variety of purposes. In some cases, the membrane may allow for mass transfer of a chemical species from a first gas mixture to a second gas mixture. In some cases, the membrane may allow for mass transfer of a chemical species from a gas phase to a liquid phase. In some cases, the membrane may allow for mass transfer of a chemical species from a first liquid mixture to a second liquid mixture. In some cases, the membrane may allow for mass transfer of a chemical species to a catalytic site where a chemical reaction may occur. In some cases, the membrane may be utilized to perform both chemical separation and catalysis. In some cases, the membrane may be cycled between separation and catalysis by the directional application of an electric field or other field or force. In other cases, the membrane may perform simultaneous catalysis and chemical separation.

[0105] In some cases, heat exchangers and cooling or heating systems can be used to maintain the desired temperature within the various reservoirs, stacks, and other unit elements. In some cases, the contactor unit in which the chemical reduction occurs can include a microstructured or nanostructured membrane. The microstructured or nanostructured membrane may include one or more catalysts. In other cases, the catalysis process can include a traditional electrochemical "stack" that includes an anode and a cathode in the same housing. In some cases, ion exchange membranes may be used. In some cases, various catalytic membranes can be used, or alternatively, other reduction methods may achieve the desired reduction of CO2. Oxygen and other oxidizing species are also produced by such processes and can be released to the atmosphere or used for beneficial purposes.

[0106] An example system and method for capturing captured CO2 from air using an electrolyte solution is provided.

[0107] Various embodiments of the integrated CO2 capture process are possible, which will result in dissolving CO2 in the electrolyte. Optionally, as depicted in FIG. 1, an electrolyte stream 102 containing an electrolyte solution for use in the electrochemical CO2 reduction process can flow from a reservoir 101 to a contactor 103 where it contacts a CO2-containing gas. The CO2-containing gas may be air from the atmosphere. Optionally, the pH of the electrolyte stream 102 can be controlled so that CO2 is captured from the CO2-containing gas into the electrolyte solution. Optionally, the temperature of the electrolyte stream 102 can be controlled so that CO2 is absorbed from the CO2-containing gas into the electrolyte solution. After leaving the contactor 103, the electrolyte stream 110 can be directed to a second electrolyte reservoir 108. Optionally, the CO2-containing gas also contains water, which may also be absorbed by the electrolyte stream. The temperature of the electrolyte stream 102 or any other component of the contactor 103 can be controlled to facilitate, among other things, the capture of water. Since water may be a reactant in the conversion of CO2 to hydrocarbons, water may be fed to the reaction from different sources, such as capture with air and / or CO2 from another source. If the temperature of the absorption fluid is lowered below the dew point of the CO2-containing gas source (e.g., air), water may be simultaneously captured by condensation from the air.

[0108] In another example, as shown in FIG. 2, an electrolyte stream 202 containing an electrolyte solution for use in an electrochemical CO2 reduction process can be directed from an electrolyte reservoir 201 to a pH control unit 204. The pH of the electrolyte stream 202 can be adjusted to facilitate capture of CO2. The pH control unit 204 can raise the pH of the electrolyte stream 202 to between 10 and 15. For example, the stream 211 can have a pH of about 10, 11, 12, 13, 14, or 15 after passing through the pH control unit 204. Optionally, the electrolyte stream 211 can enter a contactor 203 where it contacts a CO2-containing fluid. Optionally, the CO2-containing fluid is air. Capture of CO2 in the contactor 203 can reduce the pH of the electrolyte to between 7 and 9. For example, after capture of CO2 in the contractor 203, the stream 210 can have a pH of about 7, 8, or 9. After exiting the contactor 203, the electrolyte stream 210 may continue into a second electrolyte reservoir 208. Optionally, the CO2-containing gas also contains water, which may also be absorbed. Optionally, the temperature of the electrolyte stream or any other component of the contactor 203 may be controlled to facilitate, among other things, water capture. In some embodiments, the CO2 is reduced in a pH control unit. In some embodiments, the pH control unit is in a separate housing from the contactor. In some embodiments, the pH control unit and the contactor are in the same housing. In some embodiments, the housing has multiple compartments or chambers. In some embodiments, the pH control unit is in a separate compartment or chamber from the compartment or chamber containing the contactor. In some embodiments, the pH control unit is in the same chamber as the contactor. In some embodiments, the pH control unit is contained within the membrane.

[0109] In another example, as shown in FIG. 3, an electrolyte stream 302 containing an electrolyte solution used in an electrochemical CO2 reduction process can be directed from an electrolyte reservoir 301 to a pH control unit 304. The pH of the electrolyte stream 302 can be adjusted to facilitate the capture of CO2. The pH control unit 304 can adjust the pH of the electrolyte stream to 10-15. For example, the stream 311 can have a pH of about 10, 11, 12, 13, 14, or 15 after passing through the pH control unit 304. Optionally, the electrolyte stream 311 can enter a contactor 303 where it contacts a CO2-containing fluid. Optionally, the CO2-containing fluid is air. After exiting the contactor 303, the electrolyte stream 312 can subsequently enter a second pH control unit 307. The pH of the electrolyte stream 312 can be adjusted to facilitate the reduction of CO2. The second pH control unit 307 can adjust the pH of the electrolyte stream to 7-10. For example, the stream 310 may have a pH of about 7, 8, 9, or 10 after capturing the CO2 in the contractor 307. The electrolyte stream 310 may continue to a second electrolyte reservoir 308. In some cases, the CO2-containing gas also contains water, which may also be absorbed. In some cases, the temperature of the electrolyte stream or any other component of the contactor 303 may be controlled to facilitate capture of water, among other things. In some embodiments, the CO2 is reduced in the pH control unit. In some embodiments, the electrolyte stream 310 may also contain reduced carbon products. In some embodiments, the reduced carbon products are separated from the electrolyte stream 310. In some embodiments, the electrolyte stream 310 may be recycled in an electrochemical reduction system. In some embodiments, the pH control unit is in a separate housing from the contactor. In some embodiments, the pH control unit and the contactor are in the same housing. In some embodiments, the housing has multiple compartments or chambers. In some embodiments, the pH control unit is in a separate compartment or chamber from the compartment or chamber containing the contactor. In some embodiments, the pH control unit is in the same chamber as the contactor, hi some embodiments, the pH control unit is contained within the membrane.

[0110] In another example, as shown in FIG. 4, an electrolyte stream 402 containing an electrolyte solution used in an electrochemical CO2 reduction process can be directed from an electrolyte reservoir 401 to a pH control unit 406. The pH control unit 406 can adjust the pH of the electrolyte stream 402 to facilitate the capture of CO2. The pH control unit 406 can adjust the pH of the electrolyte stream 402 to between 10 and 15. For example, the stream 411 can have a pH of about 10, 11, 12, 13, 14, or 15 after passing through the pH control unit 406. Optionally, the electrolyte stream 411 can enter a contactor 403 where it can contact a CO2-containing fluid. Optionally, the CO2-containing fluid is ambient air. After exiting the contactor 403, the electrolyte stream 412 can re-enter the pH control unit 406. The pH control unit 406 can adjust the pH of the electrolyte stream 412 to facilitate the reduction of CO2. The pH control unit 406 can adjust the pH of the electrolyte stream 412 to between 7 and 10. After passing through the pH control unit 406, the stream 410 may have a pH of about 7, 8, 9, or 10. The electrolyte stream 410 may continue into a second electrolyte reservoir 408. Optionally, the CO2-containing gas also contains water, which may also be absorbed. Optionally, the temperature of the electrolyte stream or any other component of the contactor 403 may be controlled to specifically facilitate the capture of water. The pH control unit 406 may be a bipolar membrane stack or an electrochemical stack that can increase the pH of one input stream 402 and decrease the pH of the other input stream 412. For example, the pH of stream 402 may be lower than the pH of stream 411, and the pH of stream 412 may be higher than the pH of stream 410. The pH control unit 406 may be an electrochemical stack that can reduce CO2. The CO2 is captured in the electrolyte stream 412 and may be in the form of bicarbonate or carbonate ions. A reduction reaction that may occur within the electrochemical stack 406 may produce hydroxide ions. The hydroxide ions may diffuse through the anion exchange layer of the membrane stack and migrate toward the anode, which may be in contact with the input electrolyte stream 402. Hydroxide ions may be added to stream 402. The addition of hydroxide ions may increase the pH of stream 402 and decrease the pH of stream 412.In some embodiments, the electrolyte stream 410 may also include reduced carbon products. In some embodiments, the reduced carbon products are separated from the electrolyte stream 410. In some embodiments, the electrolyte stream 410 may be reused in the electrochemical reduction system. The electrochemical stack 406 may not be optimized for CO2 reduction, but rather for pH adjustment. In some embodiments, the CO2 is reduced in the pH control unit. In some embodiments, the pH control unit is in a separate housing from the contactor. In some embodiments, the pH control unit and the contactor are in the same housing. In some embodiments, the housing has multiple compartments or chambers. In some embodiments, the pH control unit is in a separate compartment or chamber from the compartment or chamber containing the contactor. In some embodiments, the pH control unit is in the same chamber as the contactor. In some embodiments, the pH control unit is contained within the membrane.

[0111] In another example, as shown in FIG. 5, an electrolyte stream 502 containing an electrolyte solution used in the electrochemical CO2 reduction process can be directed from an electrolyte reservoir 501 to a pH control unit 504. The pH of the electrolyte stream 502 can be adjusted to facilitate the capture of CO2. Optionally, after passing through the pH control unit 504, the electrolyte stream 511 can enter a contactor 503 where it contacts a CO2-containing fluid. Optionally, the CO2-containing fluid is ambient air. After leaving the contactor 503, the electrolyte stream 512 can subsequently enter a second pH control unit 507. In some embodiments, the CO2 is reduced in the pH control unit 507. In some embodiments, the electrolyte stream 510 can also include a reduced carbon product. In some embodiments, the reduced carbon product is separated from the electrolyte stream 510. In some embodiments, the electrolyte stream 510 can be reused in the electrochemical reduction system. The pH of the electrolyte stream 512 can be adjusted to facilitate the reduction of CO2. After passing through the pH control unit 507, the electrolyte stream 510 may continue into a second electrolyte reservoir 508. Alternative methods of generating acid and base streams 509 may be used to generate the acid 513 and base 514 used to adjust the pH in the pH control units 507 and 504, respectively. Optionally, the CO2-containing gas also contains water, which may also be absorbed. Optionally, the temperature of the electrolyte stream or any other component of the contactor 503 may be controlled to facilitate, among other things, the capture of water. In some embodiments, the CO2 is reduced in the pH control unit. In some embodiments, the pH control unit is in a separate housing from the contactor. In some embodiments, the pH control unit and the contactor are in the same housing. In some embodiments, the housing has multiple compartments or chambers. In some embodiments, the pH control unit is in a separate compartment or chamber from the compartment or chamber containing the contactor. In some embodiments, the pH control unit is in the same chamber as the contactor. In some embodiments, the pH control unit is contained within the membrane.

[0112] In another example, as depicted in FIG. 6, an electrolyte stream 602 containing an electrolyte solution used in an electrochemical CO2 reduction process can flow from a reservoir 601 to a contactor 605 where it contacts a CO2-containing gas. The CO2-containing gas can be atmospheric air. Optionally, the pH of the electrolyte stream 602 can be controlled so that CO2 is captured from the CO2-containing gas into the electrolyte solution. Optionally, the temperature of the electrolyte stream 602 can be controlled so that CO2 is captured from the CO2-containing gas into the electrolyte solution. The contactor 605 can include a material that promotes the capture of CO2 from the CO2-containing gas. In some embodiments, the material is a solid adsorbent. Optionally, the material is a solid substrate for a reactive chemical adsorbent. One example of such a material is polystyrene beads functionalized with amines. Another example is activated or nanostructured carbon materials such as carbon nanotubes, buckminsterfullerene, or graphene. After exiting the contactor 605, the electrolyte stream 610 can proceed to a second electrolyte reservoir 608. In some cases, the CO2-containing gas also contains water, which may also be absorbed. The temperature of the electrolyte stream 602 or any other component of the contactor 605 may be controlled to specifically facilitate water capture.

[0113] In another example, as depicted in FIG. 7, an electrolyte stream 702 containing an electrolyte solution for use in an electrochemical CO2 reduction process can be directed from an electrolyte reservoir 701 to a pH control unit 706. The pH of the electrolyte stream 702 can be adjusted to facilitate capture of CO2. The pH control unit 706 can adjust the pH of the electrolyte stream to between 10 and 15. The stream 711 can have a pH of about 10, 11, 12, 13, 14, or 15 after passing through the pH control unit 706. Optionally, the pH adjusted electrolyte stream 711 can enter a contactor 703 and be contacted with a liquid material sufficient to capture CO2. The liquid material can be an aqueous hydroxide solution, an amine solution, an ionic liquid, or other liquid material sufficient to capture CO2. The dilute CO2 capture liquid 715 can exit the contactor 703 and be directed to a contactor 705 where it can be contacted with a CO2-containing fluid. The CO2-containing fluid can be atmospheric air. The CO2-rich capture liquid 716 can exit the contactor 705 and be directed to the contactor 703 where it can contact the electrolyte stream 711. The CO2-enriched electrolyte stream 712 can exit the contactor 703 and be directed to the pH control unit 706. The pH of the electrolyte stream 712 can be optimized to promote the reduction of CO2. The pH control unit 706 can adjust the pH of the electrolyte stream to between 7 and 10. For example, the stream 710 can have a pH of about 7, 8, 9, or 10 after passing through the pH control unit 706. The pH-adjusted electrolyte stream 710 can then enter the second electrolyte reservoir 708. In some embodiments, the electrolyte stream 710 can also include reduced carbon products. In some embodiments, the reduced carbon products are separated from the electrolyte stream 710. In some embodiments, the electrolyte stream 710 can be reused in the electrochemical reduction system. In some cases, the CO2-containing gas also includes water, which can also be absorbed. Optionally, the temperature of the electrolyte stream or any other component of the contactor 703 can be controlled to facilitate, among other things, water capture. The pH control unit 706 can be a bipolar membrane stack or an electrochemical stack that can increase the pH of one input stream 702 and decrease the pH of the other input stream 712.For example, the pH of stream 702 may be lower than the pH of stream 711, and the pH of stream 712 may be higher than the pH of stream 710. The pH control unit 706 may be an electrochemical stack capable of reducing CO2. The CO2 may be captured in an electrolyte solution and may be in the form of bicarbonate or carbonate ions. The reduction reaction in 706 may produce hydroxide ions. The hydroxide ions may diffuse through the anion exchange layer of the electrochemical stack and migrate toward the anode, increasing the pH of stream 702 and decreasing the pH of stream 712. This electrochemical stack 706 may not be optimized for CO2 reduction, but rather for pH adjustment. In some embodiments, the CO2 is reduced in the pH control unit. In some embodiments, the pH control unit is in a separate housing from the contactor. In some embodiments, the pH control unit and the contactor are in the same housing. In some embodiments, the housing has multiple compartments or chambers. In some embodiments, the pH control unit is in a separate compartment or chamber from the compartment or chamber containing the contactor. In some embodiments, the pH control unit is in the same chamber as the contactor, hi some embodiments, the pH control unit is contained within the membrane.

[0114] In another example, as depicted in FIG. 8, an electrolyte stream 802 containing an electrolyte solution for use in an electrochemical CO2 reduction process can be directed from an electrolyte reservoir 801 to a contactor 805 where it can be contacted with a liquid material sufficient to capture CO2. The liquid material can be an aqueous hydroxide solution, an amine solution, an ionic liquid, or other liquid material. A dilute CO2 capture liquid 811 can exit the contactor 805 and be directed to a contactor 803 where it can be contacted with a CO2-containing fluid. The CO2-containing fluid can be atmospheric air. A CO2-rich capture liquid 812 can exit the contactor 803 and be directed to a contactor 805 where it can be contacted with the electrolyte stream 802. A CO2-rich electrolyte stream 810 can exit the contactor 805 and continue into a second electrolyte reservoir 808. In some cases, the CO2-containing gas also contains water, which can also be absorbed. In some cases, the temperature of the electrolyte stream or any other component of the contactor 805 can be controlled to facilitate capture of water, among other things. The contactor 805 may be a bipolar membrane stack, including an anion exchange membrane, a cation exchange membrane, or a bipolar membrane stack. The contactor 805 may also have a membrane that may selectively allow transport of carbon-containing species from the CO2-rich capture liquid 812 to the electrolyte stream 802. The contactor 805 may also adjust the pH of the input streams 802 and 812.

[0115] In some embodiments, the contactor, the pH control unit, and the electrochemical reduction system including the anode and the cathode may be in the same housing. In some embodiments, the contactor may be in a separate housing from the pH control unit and the electrochemical reduction system including the anode and the cathode. In some embodiments, the pH control unit and the electrochemical reduction system including the anode and the cathode may be in the same housing. In some embodiments, the contactor, the pH control unit, and the electrochemical reduction system including the anode and the cathode may be housed in separate housings. In some embodiments, the electrochemical reduction system having the anode and the cathode may further include an additional chamber or compartment that houses the anode, the cathode, a power source, a membrane, or a combination thereof.

[0116] Computer Systems The present disclosure provides a computer system programmed to implement the methods of the present disclosure. Figure 12 shows a computer control system 1201 programmed or otherwise configured to control a chemical reduction system or a process within the chemical reduction system (e.g., controlling and balancing the pH of an electrolyte stream). The computer control system 1201 can regulate various aspects of the methods of the present disclosure, such as, for example, a method of producing a reduced carbon product or a method of monitoring potentially dangerous operating conditions. The computer control system 1201 can be implemented on a user's electronic device or a computer system located remotely relative to the electronic device. The electronic device can be a portable electronic device.

[0117] The computer system 1201 includes a central processing unit (CPU, herein "processor" and "computer processor") 1205, which may be a single-core or multi-core processor, or multiple processors for parallel processing. The computer system 1201 also includes memory or memory locations 1210 (e.g., random access memory, read-only memory, flash memory), an electronic storage unit 1215 (e.g., hard disk), a communication interface 1220 (e.g., network adapter) for communication with one or more other systems, and peripheral devices 1225, such as cache, other memory, data storage, and / or electronic display adapters. The memory 1210, the storage unit 1215, the interface 1220, and the peripheral devices 1225 communicate with the CPU 1205 via a communication bus (solid lines), such as a motherboard. The storage unit 1215 may be a data storage unit (or data repository) for storing data. The computer system 1201 may be operatively coupled to a computer network ("network") 1230 with the aid of the communication interface 1220. The network 1230 may be the Internet, an Internet and / or an extranet, or an intranet and / or an extranet in communication with the Internet. In some cases, the network 1230 is a telecommunications and / or data network. The network 1230 may include one or more computer servers that may enable distributed computing, such as cloud computing. In some cases, the network 1230 may implement a peer-to-peer network with the aid of the computer system 1201, which may enable devices coupled to the computer system 1201 to operate as clients or servers.

[0118] The CPU 1205 may execute a sequence of machine-readable instructions, which may be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 1210. The instructions may be directed to the CPU 1205, which may then program or configure the CPU 1205 to implement the methods of the present disclosure. Examples of operations performed by the CPU 1205 may include fetch, decode, execute, and writeback.

[0119] The CPU 1205 may be part of a circuit, such as an integrated circuit. One or more other components of the system 1201 may be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

[0120] The storage unit 1215 can store files such as drivers, libraries, and saved programs. The storage unit 1215 can store user data, such as user preferences and user programs. In some cases, the computer system 1201 can include one or more additional data storage units that are external to the computer system 1201, such as located on a remote server that communicates with the computer system 1201 via an intranet or the Internet.

[0121] The computer system 1201 can communicate with one or more remote computer systems via the network 1230. For example, the computer system 1201 can communicate with a remote computer system of a user (e.g., a user monitoring the pH and temperature of an electrolyte stream). Examples of remote computer systems include a personal computer (e.g., a portable PC), a slate or tablet PC (e.g., Apple® iPad®, Samsung® Galaxy Tab), a phone, a smartphone (e.g., Apple® iPhone®, Android-enabled device, Blackberry®), or a personal digital assistant. The user can access the computer system 1201 via the network 1230.

[0122] The methods described herein may be implemented by machine (e.g., computer processor) executable code stored in electronic storage locations of the computer system 1201, such as, for example, memory 1210 or electronic storage unit 1215. The machine executable or machine readable code may be provided in the form of software. During use, the code may be executed by the processor 1205. In some cases, the code may be retrieved from the storage unit 1215 and stored in the memory 1210 for easy access by the processor 1205. In some circumstances, the electronic storage unit 1215 may be omitted and the machine executable instructions are stored in the memory 1210.

[0123] The code may be pre-compiled and configured for use with a machine having a processor configured to execute the code, or it may be compiled at run-time. The code may be provided in a programming language that may be selected to render the code executable in a pre-compiled or as-compiled manner.

[0124] Aspects of the systems and methods provided herein, such as computer system 1201, may be embodied in programming. Various aspects of the technology may be considered as "products" or "articles of manufacture," typically in the form of machine (or processor) executable code and / or associated data carried or embodied on some type of machine-readable medium. The machine-executable code may be stored in an electronic storage unit, such as a memory (e.g., read-only memory, random access memory, flash memory) or a hard disk. A "storage" type medium may include any or all of the tangible memory of a computer, processor, etc., or its associated modules, such as various semiconductor memories, tape drives, disk drives, etc., that may provide non-transitory storage for software programming at any given time. All or portions of the software may at times be communicated over the Internet or various other telecommunications networks. Such communication may, for example, enable loading of the software from one computer or processor to another, such as a management server or host computer to the computer platform of an application server. Thus, other types of media that may carry software elements include light waves, radio waves, and electromagnetic waves, such as those used across physical interfaces between local devices, through wired and optical landline telephone networks, and over various air links. For example, the physical elements that carry such waves, such as wired or wireless links, optical links, etc., may also be considered software-bearing media. As used herein, unless limited to non-transitory tangible "storage" media, terms such as computer or machine "readable medium" refer to any medium that participates in providing instructions to a processor for execution.

[0125] Thus, a machine-readable medium such as a computer executable code may take many forms, including but not limited to tangible storage media, carrier wave media, or physical transmission media. Non-volatile storage media include optical or magnetic disks, such as any of the storage devices of any (one or more) computer, such as may be used to implement, for example, the databases shown in the figures. Volatile storage media include dynamic memory, such as the main memory of such a computer platform. Tangible transmission media include coaxial cables, copper wire and optical fibers, including the wiring that makes up a bus within a computer system. Carrier wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer readable media thus include, for example, a floppy disk, a flexible disk, a hard disk, a magnetic tape, any other magnetic medium, a CD-ROM, a DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium having a pattern of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave carrying data or instructions, a cable or link carrying such a carrier wave, or any other medium from which a computer may read programming code and / or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[0126] The computer system 1201 can include or communicate with an electronic display 1235 that includes a user interface (UI) 1240 for providing, for example, the pH and / or temperature of the electrolyte stream. Examples of UIs include, but are not limited to, a graphical user interface (GUI) and a web-based user interface.

[0127] The methods and systems of the present disclosure can be implemented by one or more algorithms. The algorithms can be implemented by software when executed by the central processing unit 1205. The algorithms can, for example, adjust the flow rate of a gas stream containing CO2 through a contactor to optimize the pH or bicarbonate concentration of an electrolyte solution. As another example, the algorithms can adjust the electric field applied to a microstructured or nanostructured membrane to control the selectivity of the membrane to a particular chemical species. EXAMPLES

[0128] Converting CO2 to ethanol In one example, CO2 is captured from an incoming air stream and reduced to ethanol. In this example, the incoming air stream containing CO2 is directed into a contactor of an electrochemical reduction system. An electrolyte solution can also be directed to the contactor. The electrolyte solution can include water. When the air stream is contacted with the water, CO2 can react with the water to form bicarbonate ions and hydronium ions via carbonic acid. At this point, CO2 can be captured by the water molecules as bicarbonate ions. The water stream containing bicarbonate ions is directed to a compartment with a membrane and a power source. The bicarbonate ions are converted to form ethanol ions and hydroxide ions when a voltage is applied (e.g., reduction). In some cases, the reduced carbon product, ethanol, can pass through the membrane to be separated, among other things, from unreacted bicarbonate and hydroxide ions. As the reduced carbon product passes through the membrane, the pH of the solution on the original side of the membrane can increase. The increased pH can promote the conversion of unreacted bicarbonate ions to carbonate ions and water. Additionally, the increased pH solution can further promote the capture of CO2 from the incoming air stream into the water. Thus, through the production of water and / or hydroxide ions, the electrolyte is regenerated and can be used to repeat the cycle of carbon dioxide capture and reduction one or more times.

[0129] The methods and systems of the present disclosure may be combined with or modified by other methods and systems, such as those disclosed in U.S. Pat. No. 10,590,548 and WO / 2020 / 131837, each of which is incorporated by reference in its entirety.

[0130] While preferred embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the present invention be limited by the specific examples provided herein. Although the present invention has been described with reference to the above specification, the description and illustration of the embodiments herein are not intended to be construed in a limiting sense. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the present invention. Furthermore, it will be understood that all aspects of the present invention are not limited to the specific figures, configurations or relative proportions described herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the present invention described herein may be used in carrying out the present invention. It is therefore contemplated that the present invention shall encompass any such alternatives, modifications, variations or equivalents. It is intended that the appended claims define the scope of the present invention, and that methods and structures within the scope of these claims and their equivalents are covered thereby.

Claims

1. Carbon Dioxide (CO ２ 1. A method for the electrochemical reduction of (a) directing a first flow comprising an electrolyte solution toward a contactor; (b) In the contactor, CO ２ contacting an incoming air stream containing ２ to obtain a second stream comprising the electrolyte solution and one or more bicarbonate ions; and (c) directing the second flow from the contactor to an electrochemical stack including an anode and a cathode; (d) reducing the one or more bicarbonate ions in the electrochemical stack by applying a voltage between the cathode and the anode to produce a reduced carbon product, thereby obtaining a third stream comprising the electrolyte solution and the reduced carbon product; (e) separating at least a portion of said carbon product from said third stream, thereby obtaining (i) a separated reduced carbon product and (ii) a fourth stream comprising said electrolyte solution; (f) directing the fourth stream back to the electrochemical stack, adjusting the pH of the fourth stream, and removing additional CO from the incoming air stream. ２ wherein the electrochemical stack adjusts a pH of the fourth stream without introducing additional electrolyte, additional acidic solution, or additional basic solution into the electrolyte solution.

2. 2. The method of claim 1, wherein in (d), one or more hydroxide ions are generated, which shift bicarbonate ions to carbonate ions, thereby maintaining an optimal pH in the electrochemical stack for further CO2 reduction.

3. The method of claim 2 , wherein the pH of the first stream is greater than the pH of the fourth stream.

4. 4. The method of claim 3, wherein in (f), the fourth stream contacts the one or more hydroxide ions.

5. 5. The method of claim 4, wherein the pH of the first stream is between about 10 and about 15.

6. 10. The method of claim 1, wherein in (d) one or more hydrogen ions or other acidic species are generated.

7. The method of claim 6 , wherein the pH of the second stream is greater than the pH of the third stream.

8. 8. The method of claim 7, wherein in (d), the second stream contacts the one or more hydrogen ions or the other acidic species.

9. 9. The method of claim 8, wherein the pH of the third stream is between about 7 and about 10.

10. The method of claim 1 , wherein in (c), the second flow enters the electrochemical stack in a first direction.

11. 11. The method of claim 10, wherein in (f), the fourth flow enters the electrochemical stack in a second direction, the second direction being opposite to the first direction.

12. 12. The method of claim 11, wherein the electrochemical stack comprises a bipolar membrane stack configured to increase a pH of the fourth stream when the fourth stream flows in the first direction through the electrochemical stack and to decrease a pH of the second stream when the second stream flows in the second direction through the electrochemical stack.

13. The temperature or range of the first stream is controlled to remove H from the incoming air stream. ２ 10. The method of claim 1, further comprising promoting absorption of O.

14. 14. The method of claim 13, wherein controlling the temperature or range thereof of the first stream comprises using a heat exchanger or a cooling or heating system.

15. Controlling the temperature or range thereof includes reducing a temperature of the first flow below a dew point of the incoming air stream, thereby reducing the H from the incoming air stream. ２ 14. The method of claim 13, wherein condensation of O and said absorption is promoted.

16. The contactor removes the CO from the incoming air stream. ２ 10. The method of claim 1, further comprising: a sorbent to facilitate said capture of said ions, said sorbent comprising a solid substrate comprising a reactive chemisorbent selected from the group consisting of amine-functionalized polystyrene beads, carbon nanotubes, buckminsterfullerene, and graphene.

17. 10. The method of claim 1, wherein the reduced carbon products comprise compounds having two or more carbon atoms.

18. 10. The method of claim 1 , wherein the separating in (e) comprises passing the third stream through a membrane comprising carbon nanotubes, carbon nanospheres, carbon nano-onions, graphene-like materials, or pyrolyzed porous carbon materials, or any combination thereof.

19. The reduced carbon product is CO ２ 2. The method of claim 1, wherein the carbon isotope signature of the nucleophile comprises a unique carbon isotope signature that matches a carbon isotope signature of

20. the unique carbon isotope signature of the reduced carbon product is greater than -25‰; １３ 20. The method of claim 19, comprising the per mille difference between the natural isotope ratio of carbon and the measured isotope ratio for C.

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