INTEGRATED DIRECT AIR CAPTURE AND ELECTROCHEMICAL REDUCTION

OF CARBON DIOXIDE

CROSS-REFERENCE

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

BACKGROUND

[0002] There is an increasing level of carbon-containing compounds, such as carbon monoxide (CO) and carbon dioxide (CO2), in the atmosphere. Such increase in the level of carbon-containing compounds may be adversely impacting the global temperature, leading to global warming.

SUMMARY

[0003] The present disclosure provides systems and methods for an integrated direct air capture of reactants from the atmosphere for use in an aqueous electrochemical carbon dioxide (CO2) reduction process. An integrated method of direct air capture of CO2 may be used to achieve the cost-effective production of fuels and materials by electrochemical conversion of CO2.

[0004] Recognized herein is an increased need for efficient methods of producing fuels and other chemical commodities from non-petroleum sources and reducing the level of CO2 in the atmosphere. Electrocatalytic reduction of CO2 into fuels and materials (e.g., building materials) has long been known to be technically feasible, but it has not been economically practical, in part due to the low efficiency of catalysts for the most useful products (like liquid transportation fuels or polymer monomers), but also due to the cost of capturing CO2 from the atmosphere, separating the reduced carbon materials (for example water miscible products requiring distillation, such as ethanol), and upgrading reduced products into finished end products.

[0005] Carbon species that may be produced from the electrochemical reduction (i.e., adding of electrical energy in the form of chemical bonds) of CO2are many, including carbon monoxide, hydrocarbon gases, alcohols, aldehydes, organic acids, and to a lesser degree longer chain hydrocarbons. Of these, many have a high a potential for conversion to useful products, including transportation fuels and polymers. Methods of capturing CO2 from the air have included the use of materials sufficient to capture CO2 brought in contact with the air to capture CO2, which is present in low concentrations but has relatively high chemical reactivity. A material sufficient to capture CO2 may be an adsorbent or absorbent material. In some instances, a material sufficient to capture CO2 may be a solvent configured to dissolve CO2. Adsorbents may include solid adsorbents with reactive functional groups. Absorbents may include aqueous hydroxide solutions, non-aqueous reactive liquids. In some instances, a material sufficient to capture CO2 may be an electrolyte solution. In some instances, an electrolyte solution may be aqueous or non-aqueous. In previous cases, the goal has been to produce a pure CO2 gas stream, which involves a high degree of change in the entropy of the gas. An integrated CO2 capture process that results in the dissolution of CO2 into an electrolyte, such as bicarbonate/carbonate solutions, would require much less change in entropy than converting it into a pure gas. This can result in large energy savings. Additionally, by capturing CO2 into an electrolyte that will be used in an electrochemical CO2 reduction process, significant reductions in capital equipment and process complexity may be achieved.

[0006] In an aspect, described herein is a method for integrated direct air capture of carbon dioxide (C02) for aqueous electrochemical reduction of C02, comprising: (a) contacting input air stream with an electrolyte solution, wherein the input air stream comprises C02, to capture at least a subset of the C02 from the input air stream into the electrolyte solution; and (b) reducing the at least the subset of the C02 using the electrolyte solution to generate reduced carbon products.

[0007] In some embodiments, the capture of the at least the subset of the C02 comprises absorption or adsorption by the electrolyte solution.

[0008] In some embodiments, the input air stream has a C02 concentration of at most 1000 ppm. In some embodiments, the input air stream has a C02 concentration of at most 500 ppm. In some embodiments, the input air stream has a C02 concentration of at most 420 ppm.

[0009] In some embodiments, the input air stream comprises water (H20), and subsequent to (a), at least a subset of the H20 is absorbed by the electrolyte solution. In some embodiments, the method further comprises controlling a temperature or range thereof of the electrolyte solution to facilitate capture of the H20. [0010] In some embodiments, the reducing in (b) is in the absence of an independent hydrogen feed to the electrolyte solution.

[0011] In some embodiments, (a) comprises subjecting the electrolyte solution to flow from a first electrolyte reservoir to a contactor, wherein the input air stream and the electrolyte solution is contacted at the contactor. In some embodiments, the method further comprises 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 C02 to facilitate adsorption of the at least the subset of the C02 from the input air stream. In some embodiments, the material sufficient to capture C02 comprises water. In some embodiments, the material sufficient to capture C02 comprises a solid substrate comprising reactive chemical adsorbents. In some embodiments, the material sufficient to capture C02 comprises a polystyrene bead functionalized with amines. In some embodiments, the material sufficient to capture C02 comprises activated or nanostructured carbon materials. In some embodiments, the activated or nanostructured carbon materials comprise carbon nanotubes (CNTs), Buckminster fullerene, and graphene.

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

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

[0015] In some embodiments, the method further comprises controlling a pH or range thereof of the electrolyte solution subsequence to the contacting of the input air stream and the electrolyte solution. In some embodiments, the controlling comprises adjusting or maintaining a pH range of the electrolyte solution to between 7-10.

[0016] In some embodiments, the method further comprises using a pH controlling unit to adjust a pH or range thereof of the electrolyte solution (i) prior to or (ii) subsequent to the contacting of the input air stream and the electrolyte solution. In some embodiments, the pH controlling unit comprises (i) a bipolar membrane stack configured to increase a pH of the electrolyte solution when flowed through the pH controlling unit in a first direction and decrease the pH of the electrolyte solution when flowed through the pH controlling unit in a second direction different from the first direction, (ii) an electrochemical stack configured to reduce the at least the subset of the C02 and hydrogen while generating oxygen, such that a pH of the electrolyte solution increases when flowed through the pH controlling unit in a first direction and the pH of the electrolyte solution decrease when flowed through the pH controlling unit in a second direction different from the first direction. In some embodiments, the pH controlling unit comprises an acid and base supplying unit, wherein the acid and base supplying unit is configured to (i) supply an acidic solution to the electrolyte solution subsequent to the contacting of the air stream and the electrolyte solution to decrease a 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 stream and the electrolyte solution to increase a pH or range thereof of the electrolyte solution.

[0017] In some embodiments, the method further comprises prior to (a), contacting a first electrolyte solution with a C02 containing liquid material sufficient to capture C02 to output the electrolyte solution. In some embodiments, subsequent to (b), the electrolyte solution is contacted with the first electrolyte solution. In some embodiments, the liquid material sufficient to capture C02 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 the liquid material sufficient to capture C02 is contacted at a bipolar membrane stack containing an anion exchange membrane or a cation exchange membrane stack or both, wherein the bipolar membrane stack or the cation exchange membrane stack is configured to facilitate transport of carbon containing species from the liquid material sufficient to capture C02 to the first electrolyte solution.

[0018] In some embodiments, the reducing at least subset of the carbon dioxide using the electrolyte solution generates the reduced carbon products.

[0019] In some embodiments, the reduced carbon products comprise fuel. [0020] In another aspect, described herein is a composition, comprising a hydrocarbon mixture having carbon at an isotopic distribution of greater than -25%» Δ ¹³ C.

[0021] In some embodiments, the hydrocarbon mixture has carbon at an isotopic distribution of between -6%o and -9%· Δ ¹³ 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 an aspect, described herein is method for integrated direct air capture of carbon dioxide (CO ₂ ) for aqueous electrochemical reduction of CO ₂ , comprising: providing a housing comprising an electrochemical reduction system comprising an electrolyte solution, an anode, and a cathode; directing an input air stream to the housing to bring the input air stream in contact with the electrolyte solution in the housing, wherein the input air stream comprises CO ₂ , thereby capturing the CO ₂ from the input air stream into the electrolyte solution to generate a first bicarbonate ion; and while a voltage is applied between the cathode and the anode, reducing the first bicarbonate ion to generate a carbon product, wherein the electrochemical reduction system is used to adjust a pH of the electrolyte solution to facilitate capture of the CO ₂ into the electrolyte solution or facilitate CO ₂ reduction, wherein generation of the carbon product in (c): (1) produces a hydroxide ion, wherein the hydroxide ion shifts a second bicarbonate ion to a carbonate ion, and (2) regenerates carbonate ion or bicarbonate ion to maintain (i) an optimal pH for reducing additional CO ₂ , or (ii) an optimal concentration of carbonate ion or bicarbonate ion for reducing additional CO ₂ .

[0023] In some embodiments, the capture of the CO ₂ comprises absorption by the electrolyte solution. In some embodiments, the input air stream has a CO ₂ concentration of at most 500 parts per million (ppm). In some embodiments, the input air stream comprises H ₂ O, and wherein subsequent to (b), at least a subset of the H ₂ O is absorbed by the electrolyte solution. In some embodiments, the method further comprises controlling a temperature or range thereof of the electrolyte solution to facilitate capture of the H ₂ O. In some embodiments, the reducing in (c) is in the absence of an independent hydrogen feed to the electrolyte solution.

[0024] In some embodiments, the housing comprises a contactor, and in (b), the input air stream and the electrolyte solution are contacted at the contactor. In some embodiments, the method further comprises directing the electrolyte solution to an electrolyte reservoir. In some embodiments, the contactor comprises an adsorbent to facilitate capture of the CO2 from the input air stream into the electrolyte solution. In some embodiments, the adsorbent comprises a solid substrate comprising reactive chemical adsorbents selected from the group consisting of polystyrene bead functionalized with amines, carbon nanotubes (CNTs), Buckminster fullerene, and graphene. In some embodiments, the contactor comprises one or more members selected from the group consisting of: a membrane contactor, random or structured gas-liquid contacting packing, film fill, splash packing, packed falling film device, cooling tower, fluidized bed, liquid shower in contact with gases, and nanostructured or activated carbon material. In some embodiments, the membrane contactor comprises a carbon nanotube membrane, wherein a plurality of nanotubes of the carbon nanotube membrane function as pores and wherein a plurality of openings of the plurality of nanotubes are functionalized with adsorbing functional groups.

[0025] In some embodiments, the pH controlling unit adjusts or maintains a pH range of the electrolyte solution to between 9-15 or between 7-10. In some embodiments, the pH controlling unit comprises (i) a bipolar membrane stack, (ii) an electrochemical stack configured to reduce the CO2 and hydrogen while generating oxygen, such that a pH of the electrolyte solution increases when flowed through the pH controlling unit in a first direction and the pH of the electrolyte solution decrease when flowed through the pH controlling unit in a second direction different from the first direction, or (iii) an acid and base supplying unit, wherein the acid and base supplying unit is configured to (1) supply an acidic solution to the electrolyte solution subsequent to the contacting of the air stream and the electrolyte solution to decrease a pH or range thereof of the electrolyte solution and (2) supply a basic solution to the electrolyte solution prior to the contacting of the air stream and the electrolyte solution to increase a pH or range thereof of the electrolyte solution.

[0026] In some embodiments, the method further comprises, prior to (b), contacting a 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, subsequent to (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 comprises a membrane. In some embodiments, the membrane comprises a plurality of pores. In some embodiments, the membrane comprises a catalyst. In some embodiments, a pH controlling unit is separate from the housing. In some embodiments, the housing comprises compartments. [0027] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

INCORPORATION BY REFERENCE

[0028] 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 publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and/or take precedence over any such contradictory material.

BRIEF DESCRIPTION OF THE DRAWINGS

[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 “Figure” and “FIG.” herein) of which:

[0030] FIG. 1 illustrates a schematic diagram of a method for capturing CO2, in accordance with embodiments.

[0031] FIG. 2 illustrates an additional schematic diagram of a method for capturing CO2, including a method for pH control, in accordance with embodiments.

[0032] FIG. 3 illustrates an additional schematic diagram of a method for capturing CO2, including two methods for pH control, in accordance with embodiments.

[0033] FIG. 4 illustrates an additional schematic diagram of a method for capturing CO2, including a method for pH control that raises the pH of one input stream and lowers the pH of another input stream, in accordance with embodiments.

[0034] FIG. 5 illustrates an additional schematic diagram of a method for capturing CO2, including two methods for pH control and a separate method of creating acid and base streams, in accordance with embodiments. [0035] FIG. 6 illustrates an additional schematic diagram of a method for capturing CO2, including a contactor that contains a material sufficient to capture CO2, in accordance with embodiments.

[0036] FIG. 7 illustrates an additional schematic diagram of a method for capturing CO2, including a pH controller and two contactors, in accordance with embodiments.

[0037] FIG. 8 illustrates an additional schematic diagram of a method for capturing CO2, including two contactors. In one of the contactors a liquid material sufficient for capturing CO2 is contacted with a CO2 containing fluid, in accordance with embodiments. [0038] FIG. 9 illustrates the surface of a carbon nanotube membrane, with tubes acting as pores through an inert material substrate, in accordance with embodiments.

[0039] FIG. 10 illustrates a hollow fiber carbon nanotube membrane, in accordance with embodiments.

[0040] FIG. 11 illustrates a carbon nanotube pore functionalized with a desired functional group, in accordance with embodiments.

[0041] FIG. 12 illustrates a schematic of a computer system as utilized for the present invention, in accordance with embodiments.

[0042] FIGs. 13A-C illustrate examples of a separation unit of an electrochemical reduction system comprising a first compartment with a cathode and a second compartment with an anode. FIG. 13A depicts a schematic view of a separation unit where the anode and cathode are electrically coupled by a voltage source. FIG. 13B depicts a schematic view of a separation unit where the anode and the cathode are separated by a membrane. FIG. 13C depicts a schematic view of a separation unit comprising an extractor.

DETAILED DESCRIPTION

[0043] While various embodiments of the invention have been shown and described herein, it will be obvious 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 invention described herein may be employed.

[0044] Whenever the term “at least,” “greater than,” or “greater than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “at least,” “greater than” or “greater than or equal to” applies to each of the numerical values in that series of numerical values. For example, greater than or equal to 1, 2, or 3 is equivalent to greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3. [0045] Whenever the term “no more than,” “less than,” or “less than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “no more than,” “less than,” or “less than or equal to” applies to each of the numerical values in that series of numerical values. For example, less than or equal to 3, 2, or 1 is equivalent to less than or equal to 3, less than or equal to 2, or less than or equal to 1.

[0046] The terms “C1+” and “C1+ compound,” as used herein, generally refer to a compound comprising one or more carbon atoms, e.g., one carbon atom (Cl), two carbon atoms (C2), etc. C1+ compounds include, without limitation, alkanes (e.g., methane, CFk), alkenes (e.g., ethylene, C2H2), alkynes and aromatics containing two or more carbon atoms. In some cases, Cl' + compounds include aldehydes, ketones, esters and carboxylic acids. Examples of C1+ compounds include, without limitation, methane, ethane, ethylene, acetylene, propane, propene, butane, butylene, etc. A C1+ compound may also be referred to as a reduced carbon product or reduced carbon material, as used herein [0047] The term “unit,” as used herein, generally refers to a unit operation, which is a basic operation in a process. Unit operations may involve a physical change or chemical transformation, such as, for example, separation, crystallization, evaporation, filtration, polymerization, isomerization, transformation, and other reactions. A given process may require one or a plurality of unit operations to obtain the desired product(s) from a starting material(s), or feedstock(s).

[0048] The term “carbon-containing material,” as used herein, generally refers to any material comprising at least one carbon atom. In some example, a carbon-containing material is carbon monoxide (CO), carbon dioxide (CO2), or a mixture of CO and CO2. The carbon- containing material may be a material derived from CO and/or CO2, such as bicarbonate or bicarbonate ions.

[0049] The term “pH controlling unit” as used herein, generally refers to any unit operation that is used to adjust the pH of one or more input streams. In some examples, a pH controlling unit is a bipolar membrane stack. In some embodiments, a pH controlling unit is an electrochemical stack that reduces CO2. In some embodiments, a pH controlling unit is an acid or base supplying unit.

[0050] Provided herein are systems, devices, and methods for direct capture of CO2 from air, and processing thereof. The present invention may comprise an integrated CO2 capture process that results in the dissolution of CO2 into an electrolyte. An input air stream comprising CO2 may be drawn into an electrochemical reduction system that converts CO2 into hydrocarbons. [0051] The present invention may comprise contacting the input air stream with an electrolyte solution, wherein the input air stream comprises CO2, to capture at least a subset of the CO2 rom the input air stream in the electrolyte solution, and reducing the at least the subset of the CO2 using the electrolyte solution to generate reduced carbon products, such as to generate fuel. In some instances, the electrolyte solution may be regenerated subsequent to generation of reduced carbon products. In some embodiments, regenerated electrolyte may be recycled within the system to facilitate additional capture of CO2. The described systems may include one or more additional chemical conversion processes that allow the conversion of CO2-derived reduced carbon products into hydrocarbon fuels or other useful chemical products.

[0052] The method may comprise contacting the input air stream with an electrolyte solution, wherein the input air stream comprises CO2, to capture at least a subset of the CO2 from the input air stream in the electrolyte solution and reducing the at least the subset of the CO2 using the electrolyte solution to generate reduced carbon products, such as fuels or other useful chemical products.

[0053] The input air stream may comprise atmospheric air, such as air from an outdoor or indoor environment. The input air stream may comprise ambient air. The input air stream may comprise relatively low CO2 levels. For example, the CO2 concentration in the input air stream may be at most about 2000 parts per million (ppm), 1800 ppm, 1600 ppm, 1400 ppm, 1200 pm, 1000 ppm, 800 ppm, 600 ppm, 400 ppm, or less. The CO2 concentration in the input air stream may be no more than an ambient concentration of CO2 in outdoor atmospheric air (e.g., 410 ppm). Alternatively, the input air stream may comprise non- atmospheric air. The non-atmospheric air may comprise a CO2 concentration that is at most about 2000 ppm, 1800 ppm, 1600 ppm, 1400 ppm, 1200 pm, 1000 ppm, 800 ppm, 600 ppm, 400 ppm, or less. Alternatively, the input air stream may have a CO2 concentration of more than about 2000 ppm. In some embodiments, an input air stream may be directed into a compartment (e.g., first compartment or chamber) of the system. In some embodiments, the input air stream may be in contact with an electrolyte solution.

[0054] The present disclosure provides chemical conversion systems that convert CO2 to other chemicals via an electrochemical reduction system. The electrochemical reduction system may generate bicarbonate ions via the capture of CO2 from atmospheric CO2. In some instances, a CO2 reduction system may utilize a feed stream comprising CO2without the need for further purification. In some instances, a CO2 reduction system may utilize a feed stream comprising CO2 without the need for additional separation processes that enrich the CO2 composition of the feed stream. A feed stream to an electrochemical reduction system may comprise CO2 on a molar basis of 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. A feed stream to an electrochemical reduction system may comprise CO2 on a molar basis of 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. A feed stream to an electrochemical reduction system may comprise CO2 on a molar basis of 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% or less.

[0055] An electrochemical reduction system may produce reduced carbon products (e.g., hydrocarbons) at a specific rate based upon the available surface area for electrochemical reduction. An electrochemical reduction system may produce reduced carbon products at a rate of about 10 kilograms/meter squared/hour (kg/m ² /hr), 20 kg/m ² /hr, 30 kg/m ² /hr, 40 kg/m ² /hr, 50 kg/m ² /hr, 60 kg/m ² /hr, 70 kg/m ² /hr, 80 kg/m ² /hr, 90 kg/m ² /hr, 100 kg/m ² /hr, 150 kg/m ² /hr, or about 200 kg/m ² /hr. An electrochemical reduction system may produce reduced carbon products at a rate of at least about 10 kg/m ² /hr, 20 kg/m ² /hr, 30 kg/m ² /hr, 40 kg/m ² /hr, 50 kg/m ² /hr, 60 kg/m ² /hr, 70 kg/m ² /hr, 80 kg/m ² /hr, 90 kg/m ² /hr, 100 kg/m ² /hr, 150 kg/m ² /hr, or about 200 kg/m ² /hr or more. An electrochemical reduction system may produce reduced carbon products at a rate of no more than about 200 kg/m ² /hr, 150 kg/m ² /hr, 100 kg/m ² /hr, 90 kg/m ² /hr, 80 kg/m ² /hr, 70 kg/m ² /hr, 60 kg/m ² /hr, 50 kg/m ² /hr, 40 kg/m ² /hr, 30 kg/m ² /hr, 20 kg/m ² /hr, or 10 kg/m ² /hr or less.

[0056] An electrochemical reduction system may have a selectivity for the conversion of CO2 to one or more chemical species. In some instances, a 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 a product species. For example, a selectivity of 50% may indicate that 50% of entering CO2 molecules were converted to a reduced carbon species in a reactor, system or unit. In some instances, a selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are converted to a chemical species within a particular class, weight range, carbon number range, or other characteristic. For example, a selectivity of 50% Cl - C4 may indicate that 50% of entering CO2 molecules were converted to a Cl to C4 reduced carbon product. A selectivity may be a single-pass selectivity. A single-pass selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are captured and converted to a reduced carbon product on a single pass through the reactor, system, or unit. A selectivity may be a recycled selectivity. A recycled selectivity may be defined as the percentage of carbon atoms entering a reactor, system, or unit that are converted to a hydrocarbon product on two or more passes through the reactor, system, or unit.

[0057] An electrochemical reduction system may have a selectivity of about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or about 99%. An 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. An electrochemical reduction system may have a selectivity of no more than 99%, 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% or less.

[0058] An electrochemical reduction system for the conversion of CO2 into other chemicals may comprise various components that may be necessary for the reduction of CO2. Components may include cathodes, anodes, contactors, extractors, pumps, vapor-liquid separators, and ion exchange membranes. In some instances, some components may be included or excluded from a chemical reduction system depending upon the preferred embodiment of the device. In some instances, a chemical reduction system may be a single, stand-alone, or fully integrated system that performs all processes in the electrochemical reduction of CO2. In other instances, an electrochemical reduction system may comprise at least two or more operatively linked unit operations that collectively perform the necessary processes in the electrochemical reduction of CO2.

[0059] An electrochemical reduction system may comprise a housing. The housing may provide various functions to the electrochemical reduction system, including without limitation: securing components (e.g., membranes), physically containing fluids, separating differing fluids within a single unit, retaining temperature or pressure, and/or providing insulation. The housing may comprise any suitable material, including metals, ceramics, refractories, insulations, plastics, and glasses. The housing may comprise one unit of an electrochemical reduction system (e.g., a cathode). The housing may comprise two or more units of an electrochemical reduction system (e.g., a cathode and anode). A complete electrochemical reduction system may be contained within a single housing.

[0060] 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 shapes or combinations of shapes thereof. The housing may be single-piece or formed of multiple pieces (e.g., pieces welded together). The housing may include a coating on an interior portion thereof. Such coating may prevent reaction with a surface in the interior portion of the housing, such as corrosion or an oxidation/reduction reaction with the surface.

[0061] An electrochemical reduction system may comprise one or more compartments or chambers. Compartments or chambers may be defined as enclosed volumes within the electrochemical reduction system where mass transfer occurs. For example, an electrochemical reduction system may comprise a first compartment (or chamber) where a C1+ product is produced, and a separate second compartment (or chamber) where C1+ product is extracted, separated, or otherwise transferred from the first compartment. In some embodiments, a first compartment or chamber and a second compartment or chamber may comprise an electrolyte. In some embodiments, one or more compartments or chambers may comprise an anode, a cathode, a membrane, or a combination thereof. In some embodiments, a second compartment or chamber comprises an anode, a cathode, or a combination thereof. [0062] An electrochemical reduction system may comprise a contactor as described in FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 7, and FIG. 8, and may further comprise one or more compartments or chambers. Compartments or chambers may be defined as enclosed volumes within the electrochemical reduction system where mass transfer occurs. For example, an electrochemical reduction system may comprise a compartment or chamber where a C1+ product is produced, and a separate compartment or chamber where C1+ product is extracted, separated, or otherwise transferred from the first compartment.

[0063] FIGs. 13A - 13C show various examples of configurations of compartments or chambers within the scope of the present invention. In some embodiments, a chamber or compartment may further comprise additional chambers or compartments. FIG. 13A depicts a schematic view of an electrochemical reduction system 1000 where a first compartment or chamber 100 comprises a cathode 140 and a second compartment or chamber 200 comprise an anode 160, where the anode 140 and cathode 160 are electrically coupled by a voltage source 130. The first compartment or chamber 100 is separated from the second compartment or chamber 200 by a micro- or nanostructured membrane 150, which controls the transfer of C1+ product from the first compartment or chamber 100 to the second compartment or chamber 200. FIG. 13B depicts a schematic view of an electrochemical reduction system 1000 containing a cathode unit 240 and an anode unit 220. The cathode unit 240 comprises a first compartment or chamber 100 containing the cathode 140 that is electrically coupled by a voltage source 130 to an anode 160 in the anode unit 220. The first compartment or chamber 100 is separated from a second compartment or chamber 200 by a micro- or nanostructured membrane 150, which controls the transfer of C1+ product from the first compartment 100 to the second compartment or chamber 200 within the cathode unit 240. FIG. 13C depicts a schematic view of an electrochemical reduction system 1000 comprising a cathode unit 240, an anode unit 220, and an extractor 230. The cathode unit comprises a cathode 140 and a first compartment 100. The cathode 140 is electrically coupled to the anode 160 in the anode unit 220 by a voltage source 130. A C1+ product is produced in the first compartment or chamber of the cathode unit 240 and is transferred by stream C1+ to the extractor, which comprises a second compartment or chamber 200. The C1+ product is transferred from stream C1+ into the second compartment or chamber 200 by passage through a micro- or nanostructured membrane 150. In some embodiments, an electrochemical reduction system may comprise a pH controlling unit within the chamber comprising a contactor. In some embodiments, an electrochemical reduction system may comprise a pH controlling unit external to the chamber comprising a contactor.

[0064] An electrochemical reduction system may comprise a cathode, an anode and an electrolyte solution that collectively provide the necessary components for the reduction of CO2 to other chemical species. The electrolyte solution may comprise an aqueous salt solution that is composed with an optimal ionic strength and pH for the electrochemical reduction of CO2. An electrolyte solution may comprise an aqueous salt solution comprising bicarbonate ions. In some instances, an electrolyte solution may comprise an aqueous solution of sodium bicarbonate or potassium bicarbonate. In some instances, bicarbonate ions may dissociate in the presence of one or more catalysts to produce CO2 molecules for a reduction reaction. The dissolution of CO2 into the electrolyte solution may regenerate or maintain the optimal concentration of bicarbonate ions. The electrolyte solution may comprise an aqueous species comprising carbonate ions. The electrolyte solution may comprise an aqueous species comprising formate ions. The electrochemical conversion of bicarbonate to reduced carbon products may produce hydroxide ions, which can shift a portion of the remaining bicarbonate ions into carbonate ions. Absorption of CO2 may shift the carbonate ions back to bicarbonate ions. Reduced organic salts such as formate or acetate may be further reduced into desired reduced carbon products. In some instances, the electrolyte solution may be regenerated subsequent to generation of reduced carbon products. In some embodiments, regenerated electrolyte may be recycled within the system to facilitate additional capture of CO2.

[0065] An anode may comprise an elemental metal such as nickel, tin, or gold. An anode may comprise a wire mesh, metal foam or other permeable structure of the chosen anode material. An anode material may be in operative contact with an anion exchange membrane material or another physical separator that prevents contact with the cathode.

[0066] A cathode may comprise any appropriate material. In some instances, a cathode may comprise copper nanoparticles and / orN-doped carbon nanomaterials. In some instances, a cathode may comprise a micro- or nanostructured membrane material. In some instances, a cathode may comprise one or more catalysts for the electrochemical reduction of CO or CO2 or other chemical reactions. A 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 instances, the distance between the cathode and anode may be minimized to reduce resistance. In some instances, forced convective flow of electrolyte between the electrodes may further reduce electrical resistance and / or may allow for greater distance between the electrodes. In some instances, the electrodes may be in different housings, chambers, or compartments. In some instances, the anode and cathode may have a minimal distance with an ion selective membrane between them. In some instances, no ion selective membrane may be used.

[0067] An electrochemical reduction system may be configured to operate at an optimal voltage for the reduction of CO or CO2 to reduced products. An electrochemical reduction system may be arranged in a stack or series configuration to tailor the system voltage to an optimal value. An electrochemical reduction system may 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, 10 V, 15V, or about 20V. An electrochemical reduction system may 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, 10 V,

15V, or about 20V or more. An electrochemical reduction system may have an operating voltage of no more than about 20V, 15V, 10V, 5.0V, 4.0V, 3.0V, 2.0V, 1.0V, 0.75V, 0.5V, 0.4V, 0.3 V, 0.2V, or about 0.1V or less.

[0068] An electrochemical reduction system may have an optimal cathode current density. In some instances, the cathode current density may determine the rate of CO or CO2 reduction at the cathode. A cathode may be characterized by an overall electrochemical efficiency. An overall electrochemical efficiency may be defined as the percentage of electrical energy converted into chemical energy. A cathode may have a cathode current density of about 10 milli Amps/square centimeter (mA/cm ² ), 50 mA/cm ² , 100 mA/cm ² , 150 mA/cm ² , 200 mA/cm ² , 250 mA/cm ² , 300 mA/cm ² , 350 mA/cm ² , 400 mA/cm ² , 450 mA/cm ² , 500 mA/cm ² , 600 mA/cm ² , 700 mA/cm ² , 800 mA/cm ² , 900 mA/cm ² , or about 1000 mA/cm ² . A cathode may have a cathode current density of at least about 10 mA/cm ² , 50 mA/cm ² , 100 mA/cm ² , 150 mA/cm ² , 200 mA/cm ² , 250 mA/cm ² , 300 mA/cm ² , 350 mA/cm ² , 400 mA/cm ² , 450 mA/cm ² , 500 mA/cm ² , 600 mA/cm ² , 700 mA/cm ² , 800 mA/cm ² , 900 mA/cm ² , or about 1000 mA/cm ² or more. A cathode may have a cathode current density of no more than about 1000 mA/cm ² , 900 mA/cm ² , 800 mA/cm ² , 700 mA/cm ² , 600 mA/cm ² , 500 mA/cm ² , 450 mA/cm ² , 400 mA/cm ² , 350 mA/cm ² , 300 mA/cm ² , 250 mA/cm ² , 200 mA/cm ² , 150 mA/cm ² , 100 mA/cm ² , 50 mA/cm ² , 10 mA/cm ² or less.

[0069] A cathode in an electrochemical reduction system may have an overall electrochemical efficiency. A cathode may have an overall 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. A cathode may have an overall 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. A cathode may have an overall electrochemical efficiency of no more than about 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or less.

[0070] An electrolyte solution may comprise a solution with a particular ionic strength or molarity. An electrolyte may have an ionic strength of about O.Olmoles/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. An electrolyte solution may have an ionic strength of at least about 0.01M, 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 at least about 3.0M or more. An electrolyte solution may have an ionic strength of no more than 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 no more than about 0.01M or less. A salt in an electrolyte solution may have a molarity of about O.Olmoles/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. A salt in an electrolyte solution may have a molarity of at least about 0.01M, 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 at least about 3.0M or more. A salt in an electrolyte solution may have a molarity of no more than 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 no more than about 0.01M or less. A salt in an electrolyte solution may have a molarity in a range from 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 O.OlM to about 3.0M, about 0.1M to about 0.2M, about 0.1M to about 0.5M, about O.lM 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 0.25 M to about 0.5 M, about 0.25 M to about 1 M, about 0.25 M to about 3 M, about 0.5M to about 1.0M, about 0.5M to about 3.0M, or about

I .0M to about 3.0M.

[0071] An electrolyte solution may have an optimal pH for the electrochemical reduction of CO2. An electrolyte may have a pH of about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or about 14. An electrolyte may have a pH of at least about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,

II, 12, 13, 14 or more. An electrolyte solution may have a pH of no more than about 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 or less. An electrolyte solution may have a pH in a range from 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 from about 10 to about 14.

[0072] An electrolyte solution in an electrochemical reduction system may be a non- aqueous electrolyte solution. In some cases, an electrolyte solution may be an aqueous electrolyte solution. In some instances, an electrolyte solution may comprise an ionic liquid with a dissolved salt. An ionic liquid may include, but is not limited to, midazolium-based fluorinated anion ionic liquids, midazolium acetates, midazolium fluoroacetates, pyrrolidinium ionic liquids, or any combination thereof. An aqueous electrolyte solution may be water or any electrolyte dissolved in water. In some instances, an electrolyte may comprise an aqueous salt solution.

[0073] Described herein are various chemical products and reaction mixtures generated via the electrochemical reduction of CO2 captured from an input air stream. Electrochemical reduction comprises the addition of electrical energy in the form of chemical bonds. The electrochemical reduction may produce carbon species comprising of one or more members selected from the group consisting of carbon monoxide, hydrocarbon gases, alkanes, alkenes, alcohols, aldehydes, organic acids, and other organic molecules of varying chain lengths. The products of the described electrochemical reduction systems may be further processed into useful products, including transportation fuels and polymers.

[0074] Described herein are various chemical products and reaction mixtures generated via the electrochemical reduction of CO2 derived from a gas source. The gas source may be the atmosphere. The gas source may be any CCh-bearing gas stream. Chemical products may include any process stream that is exported from a chemical processing system or any process stream that undergoes no further reactive processes. A reaction mixture may include any process mixture, reagent, or compound within the confines of a chemical reactor, reactor system, or in a process stream between chemical reactors or reactor systems. The chemical products and reaction mixtures of the present invention may include organic molecules where one or more of the constituent carbon atoms are derived from CO2. In some instances, a chemical product or reaction mixture may contain only carbon atoms derived from CO2. In other instances, a chemical product may contain carbon atoms derived from CO2 and carbon atoms derived from other sources (e.g. bio fuels). In some instances, chemical products of the present invention may have a distinct carbon isotope signature that is consistent with the carbon isotope signature of CO2 derived from the atmosphere. In some instances, chemical products and reaction mixtures of the present invention may have a distinct carbon isotope signature that is consistent with the carbon isotope signature of CO2 derived from a non- atmospheric source such as the combustion of fossil fuels. The carbon isotope signature of a chemical product or reaction mixture may be measured by an isotopic ratio of ¹⁴ C: ¹² C or 1 ³ C: ¹² C. In some instances, the isotopic signature of a chemical product or reaction mixture may be measured as a per mille difference between the natural isotopic ratio of carbon and the measured isotopic ratio. A per mille difference between the natural isotopic ratio of carbon and the measured isotopic ratio for ¹⁴ C, Δ ¹⁴ C, may be calculated as:

[0075] A per mille difference between the natural isotopic ratio of carbon and the measured isotopic ratio for ¹³ C, Δ ¹³ C, may be calculated as:

A chemical product or reaction mixture may have a A ^I4 C of about -100 parts per thousand

(%o), -10%o, 0%o, 5%o, 10%0, 20%0, 30%o, 40%0, 45%o, 50%o or about 100%o. A chemical product or reaction mixture may have a Δ ^I4 C of at least about -100%o, -10%o, 0%o, 5%o, 10%o, 20%o, 30%o, 40%o, 45%o, 50%o or at least about 100%o or more. A chemical product or reaction mixture may have a Δ ^I4 C of at most about -100%o, -10%o, 0%o, 5%o, 10%o, 20%G, 30%o, 40%o, 45%o, 50%» or at most about 100%o or less. A chemical product or reaction mixture may have a Δ ¹³ C of about -40%o, -35%o, -30%o, -28%o, -26%o, -24%o, -22%o, -20%o, - 15%O, -10%o, -8%o, or about -5%o. A chemical product or reaction mixture may have a A ¹³ C of at least about -40%o, -35%o, -30% _> o, -28%o, -26%o, -24%o, -22%o, -20%o, - 15%o, -10%o, -8%o, or at least about -5%o or more. A chemical product or reaction mixture may have a A ^I3 C of at most about -40%o, -35%o, -30%», -28%o, -26%o, -24%o, -22%o, -20%o, -15%», -10%o, -8%o, or at most about -5%o or less. Provided herein are products or reaction mixtures comprising a composition that has a Δ ^{I 3} C of greater than -25%o. In one example, the Δ ^{I 3} C may correspond to that of the ambient temperature from which CO2 is captured (e.g., -8%o). Such Δ ^{I 3} C may be distinct from the isotopic signature of products derived from, for example, fossil-based fuel or bio (e.g., plant-based) fuel. In plant-based fuel, ¹³ C levels are less than that of the atmosphere, and Δ ¹³ C may be -25%o. In another example, in fossil fuel (e.g., from oil, coal, etc.), the Δ ¹³ C may be even less than plant-based fuel, i.e., less than -25%o. Alternatively, or in addition, products or reaction mixtures described herein may comprise a composition that does not have detectable sulfur, metals, and/or aromatics. Detectable levels may refer to, in one example, a composition of at most 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 may comprise a hydrocarbon mixture comprising C1+ products.

[0076] A chemical product or reaction mixture of the present invention may include gaseous, liquid, or solid substances. Chemical products and reaction mixtures of the current invention may include one or more organic compounds. Chemical products and reaction mixtures may be miscible or immiscible in water. Chemical products and reaction mixtures may be polar or nonpolar. Chemical products and reaction mixtures may be acidic, basic, or neutral. 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. Chemical products and reaction mixtures may include branched or linear compounds. Chemical products and reaction mixtures may comprise oxygen, methane, ethane, ethylene, propane, butane, hexanes, octanes, decanes, carbon monoxide, methanol, ethanol, propanol, butanol, hexanol, octanol, and formate. Chemical products and reaction mixtures may include organometallic compounds. Chemical products and reaction mixtures of the present disclosure may include compounds intended for consumer use or industrial use, such as fuels, solvents, additives, polymers, food additives, food supplements, pharmaceuticals, fertilizers, agricultural chemicals, coatings, lubricants, and building materials. Chemical products and reaction mixtures of the present disclosure may comprise a precursor, component, substituent, or substrate for a product produced by further processing.

[0077] An organic compound of the present disclosure may comprise one or more carbon atoms. In some instances, an organic compound may comprise 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 instances, an organic compound may comprise 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 instances, an organic compound may comprise no more than 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. An organic compound of the present disclosure may comprise one or more carbon atoms derived from CO or CO2. In some instances, an organic compound may comprise 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 that are derived from CO or CO2. In some instances, an organic compound may comprise 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 that are derived from CO or CO2. In some instances, an organic compound may comprise no more than 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 that are derived from CO or CO2.

[0078] A chemical product or reaction mixture of the present disclosure may comprise more than one chemical species. A chemical product or reaction mixture may 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. A chemical product or reaction mixture may 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. A chemical product or reaction mixture may be a mixture of no more than about

100, 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 no more than about 3 or less detectable chemical compounds.

[0079] A chemical product or reaction mixture of the present disclosure may comprise a particular compound at a particular weight percentage or molar percentage of the total chemical product or reaction mixture. For example, a particular chemical product may include at least about 50 wt% ethanol. In another example, a particular chemical product may include no more than about 1 wt% water. In some instances, 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 may be a specific chemical compound on a weight or molar basis. In some instances, no more than about 99%, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or no more than about 10% or less of a chemical product or reaction mixture be a specific chemical compound on a weight or molar basis.

[0080] A chemical product or reaction mixture of the present disclosure may include compounds within a particular range of molecular weights or carbon numbers. In some instances, 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 may include compounds within a particular molecular weight range or carbon number range. In some instances, no more than about 99%, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or no more than about 10% or less of a chemical product or reaction mixture may include compounds within a particular molecular weight range or carbon number range. A chemical product or reaction mixture may include compounds within a molecular weight range from about 15 g/mol to about 30 g/mol, about 15 g/mol to about 60 g/mol, about 15 g/mol to about 100 g/mol, about 15 g/mol to about 200 g/mol, about 15 g/mol to about 400 g/mol, about 15 g/mol to about 600 g/mol, about 15 g/mol to about 1000 g/mol, about 30 g/mol to about 60 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 30 g/mol to about 1000 g/mol, about 60 g/mol to about 100 g/mol, about 60 g/mol to about 200 g/mol, about 60 g/mol to about 400 g/mol, about 60 g/mol to about 600 g/mol, about 60 g/mol to about 1000 g/mol, about 100 g/mol to about 200 g/mol, about 100 g/mol to about 400 g/mol, about 100 g/mol to about 600 g/mol, about 100 g/mol to about 1000 g/mol, about 200 g/mol to about 400 g/mol, about 200 g/mol to about 600 g/mol, about 200 g/mol to about 1000 g/mol, about 400 g/mol to 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. A chemical product or reaction mixture may include compounds within a carbon number range from about Cl to about C2, about Cl to about C3, about Cl to about C4, about Cl to about C5, about Cl to about C6, about Cl to about C8, about Cl to about CIO, about Cl to about C20, about Cl to about C30, about Cl 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 CIO, 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 CIO, 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 CIO, 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 CIO, about C5 to about C20, about C5 to about C30, about C5 to about C40, about C6 to about C8, about C6 to about CIO, about C6 to about C20, about C6 to about C30, about C6 to about C40, about C8 to about CIO, about C8 to about C20, about C8 to about C30, about C8 to about C40, about CIO to about C20, about CIO to about C30, about CIO to about C40, about C20 to about C30, about C20 to about C40, or about C30 to about C40.

[0081] A chemical product or reaction mixture of the present disclosure may comprise one or more impurities. Impurities may derive from reactant streams, reactor contaminants, breakdown or decomposition products of produced organic compounds, catalyst compounds, or side reactions in the electrochemical reduction system or other chemical conversion systems described herein. A chemical product or reaction mixture may comprise one or more organic impurities such as formate or higher molecular weight alcohols. A chemical product or reaction mixture may include carbon or non-carbon nanomaterial impurities. A chemical product or reaction mixture may comprise one or more inorganic impurities derived from sources such as catalyst degradation or leaching and corrosion of processing equipment. An inorganic impurity may comprise 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. Inorganic impurities may be present in oxidized or reduced oxidation states. Inorganic impurities may be present in the form of organometallic complexes. An impurity in a chemical product or reaction mixture may be detectable by any common analysis 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 at an amount of at least about 1 part per billion (ppb), 5 ppb, 10 ppb, 50 ppb, 100 ppb, 250 ppb, 500 ppb, 750 ppb, 1 part per million (ppm), 5 ppm, 10 ppm, 50 ppm, 100 ppm or more. One or more impurities may be detectable at an amount of no more than about 100 ppm, 50 ppm, 10 ppm, 5 ppm, 1 ppm, 750 ppb, 500 ppb, 250 ppb, 100 ppb, 50 ppb, 10 ppb, 5 ppb, or no more than about 1 ppb or less.

[0082] A chemical product may have a particular level of purity. In some instances, a chemical product may have sufficient purity to achieve a particular grade or standard. A chemical product may be ACS grade, reagent grade, USP grade, NF grade, laboratory grade, purified grade or technical grade. A chemical product may have a purity that exceeds an azeotropic composition, e.g. >95% ethanol. A gaseous chemical product of the current invention may have a purity rating of about N1.0, N2.0, N3.0, N4.0, N5.0, N6.0 or greater. A chemical product may achieve a purity level according to a defined international standard.

E.g. the ASTM D-l 152/97 standard for methanol purity.

[0083] In some instances, a chemical product or reaction mixture from an electrochemical reduction system may have no detectable amount of certain impurities. In some instances, a chemical product or reaction mixture may have no detectable amount of biological molecules or derivatives thereof. A chemical product or reaction mixture may contain no detectable amount of lipids, saccharides, proteins, nucleic acids, amino acids, spores, bacteria, viruses, protozoa, fungi, animal or plant cells, or any component thereof. [0084] An electrochemical reduction system may capture CO2 and convert the CCbinto a reduced carbon product. In an example, a system may be introduced to a stream of air comprising CO2. In some examples, the input air stream comprising CChmay interact with an electrolyte solution. In some embodiments, the interaction of the input air stream comprising CO2 and electrolyte solution takes place in a contactor. In some cases, interaction of the input air stream comprising CChwith the electrolyte solution may result in the capture of the CChin the electrolyte. In some examples, the capture of CO2 may occur as adsorption of the CO2 onto the electrolyte or absorption of the CChinto the electrolyte. In some examples, the capture of CO2 may occur as a physical interaction between CChand the electrolyte (e.g., electrostatic interaction, adsorption, absorption). In some examples, capture of CO2 may occur as a chemical interaction between CChand the electrolyte. In some examples, captured CO2 molecule may be in the form of a bicarbonate ion. For example, an air stream comprising CO2 may interact with water to yield carbonic acid which may further dissociate in water to a bicarbonate ion and a hydronium ion (e.g., H ⁺ , H ₃ 0 ⁺ , or proton), as shown in the following reaction scheme:

[0085] In such examples, generation of a bicarbonate ion and hydronium ion may decrease the pH (e.g., increase acidity) of the electrolyte solution. In some embodiments, CO2 may be transported to a separate chamber or compartment while captured in electrolyte solution. In some embodiments, the CO2 is reduced in this separate chamber. In some examples, a captured CO2 molecule (e.g., bicarbonate ion) may be directly reduced in the presence of voltage to yield a reduced carbon product. In some instances, a captured CO2 may not require release (e.g., desorption) from the captured CO2 material prior to reduction into a reduced carbon product. For example, a captured CO2 may be a bicarbonate ion, and the bicarbonate ion may directly be reduced to a reduced carbon product without an additional step requiring desorption of CO2 from the bicarbonate ion. In an 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:

[0086] A reduced carbon product may comprise an alcohol, aldehyde, alkene, alkane, acid, or combination thereof. An alcohol may comprise methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tertbutanol, pentanol, isopentanol, hexanol, isohexanol, or any other straight or branched alcohol. An aldehyde may comprise methanal, ethanal, propanal, isopropanal, butanal, isobutanal, or any other straight or branched aldehyde. An alkene or alkene may be a straight-chain or branched alkene or alkane. In some embodiments, an alkene or alkane comprises 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, a reduced carbon product may further be reduced in the presence of a voltage and/or electrolyte to form additional reduced carbon products (e.g., alcohol or aldehyde) For example, an alcohol or aldehyde may be reduced in the presence of a voltage to yield longer chain reduced carbon products. In some embodiments, the conversion of C02 to ethanol and hydroxide ions is according to the following chemical reaction, where CO2 and HCO3 ^' are in equilibrium within the solution :

In some examples, generation of hydroxide ions raises the pH of the solution (e.g., decreases acidity or increases basicity). In some embodiments, applying a voltage to a captured CO2 solution may convert at least about 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, 99%, or 100% of the captured CO2 into a reduced carbon product.

[0087] In some examples, a reduced carbon product may be separated from a mixture comprising the reduced carbon product, captured CO2, electrolyte, carbon dioxide, hydroxide ions, or hydronium ions. In some examples, a reduced carbon product is separated from a mixture by passing through a membrane. In some examples, separating a reduced carbon product from a mixture by passing from a first side of a membrane to a second side of a membrane relatively increases the pH of the solution (e.g., relative concentration of hydroxide ions increases) on the first side of the membrane.

[0088] In some examples, an electrolyte solution may be regenerated for further cycles of capture and reduction. For example, hydroxide ions generated as a byproduct of reduction of captured CO2 may interact with bicarbonate ions (e.g., bicarbonate ions which were not converted to a reduced carbon product) to yield carbonate ions and water according to the following reaction scheme:

In some embodiments, water produced by the interaction of bicarbonate ions and hydroxide ions may capture additional CO2 from an air stream. Thus, the ability of the electrolyte solution (e.g., water) to capture CO2 may be regenerated. In some examples, hydroxide ions produced by the reduction of CO2 may diffuse through an anion exchange layer of a membrane stack and migrate towards an anode. In such examples, the pH of electrolyte solution that contacts the anode may increase. In some embodiments, the increased pH of the electrolyte solution facilitates additional capture of CO2. In some examples, a regenerated electrolyte solution may be recycled and reused to capture additional CO2 from an air stream. [0089] An input air stream may come into contact with an electrolyte solution. This contact may be facilitated by a contactor. An electrochemical reduction system may comprise one or more contactor units. A contactor may comprise any unit operation or separation unit that selectively separates one or more chemical species from a feed stream. In some instances, a contactor may comprise a gas adsorption column. In other instances, a contactor may comprise packing to increase a liquid solutions surface area and a fan to increase gas passage at the liquid interface. In other instances, a contactor may comprise of or contain a membrane. Such contactors may share design features with cooling towers. In some embodiments, a compartment or chamber of the system may comprise a contactor. In some examples, a first compartment or chamber of the system may comprise a contactor. [0090] An electrochemical reduction system may comprise one or more ion exchange membranes. An ion exchange membrane may comprise a cation exchange membrane, an anion exchange membrane, or a bipolar membrane. An ion exchange membrane may be in operative contact with a cathode, an anode, or both a cathode and anode. In some instances, an electrochemical reduction system may comprise no ion exchange membranes. In some instances, an ion exchange membrane may be configured to minimize the distance between the anode and the cathode. An ion exchange membrane may have a thickness of about 1 micrometer (pm), 5 pm, 10 pm, 25 pm, 50 pm, 100 pm, 125 pm, 150 pm, 200 pm, 250 pm, 300 pm, 400 pm, 500 pm, 750 pm, 1 mm, or more than 1 mm. An ion exchange membrane may have a thickness of at least about 1 pm, 5 pm, 10 pm, 25 pm, 50 pm, 100 pm, 125 pm, 150 pm, 200 pm, 250 pm, 300 pm, 400 pm, 500 pm, 750 pm, 1 millimeter (mm), or more. An ion exchange membrane may have a thickness of no more than about 1 mm, 750 pm, 500 pm, 400 pm, 300 pm, 250 pm, 200 pm, 150 pm, 125 pm, 100 pm, 50 pm, 25 pm, 10 pm, 5 pm, 1 pm, or less.

[0091] A bipolar membrane may be a bipolar membrane stack. A bipolar membrane stack may comprise a cation exchange layer (e.g., membrane) and an anion exchange layer (e.g., layer). In some instances, a bipolar membrane stack may further comprise a mechanical reinforcement between the cation exchange layer and anion exchange layer. A bipolar membrane stack may be configured such that the cation exchange layer is positioned towards a cathode and the anion exchange layer is positioned towards an anode. In some instances, a directional voltage may be applied to facilitate dissociation or regeneration of an electrolyte. In some instances, a reverse voltage bias may be applied and an electrolyte may be dissociated into a cation and anion when passing through the bipolar membrane with an applied voltage. For example, water may dissociate into hydroxide and hydronium ions when passing through the membrane with an applied voltage. In such example, the hydronium ions may diffuse through the cation exchange layer and migrate towards the cathode, and the hydroxide ions may diffuse through the anion exchange layer and migrate towards the anode. In some instances, a forward voltage bias may be applied and hydroxide ions and hydronium ions may diffuse through the cation exchange layer and anion exchange layer towards the interface of the two layers and generate water. In some instances, the generated water may diffuse out of the cation exchange layer, anion exchange layer, or a combination thereof. [0092] In some embodiments, a membrane stack may be a bipolar membrane stack. In some examples, a bipolar membrane may dissociate water into hydroxide and hydronium ions at or near the interface between the anion exchange layer and cation exchange layer, where hydroxide ions migrate towards and through the anion exchange layer and hydronium ions migrate towards and through the cation exchange layer. In some embodiments, a membrane stack may comprise an anion exchange layer separator. In such embodiments, hydroxide ions may migrate towards and through the anion exchange layer and migrate towards the anode. In some embodiments, a membrane stack may comprise a cation exchange layer separator. In such examples, hydronium ions may migrate from the anode side to the cathode side of the compartment.

[0093] The contactor may comprise a cation exchange membrane stack. The contactor may comprise a bipolar membrane that selectively allows the transport of carbon containing species to the electrolyte. The contactor may also be used adjust the pH of electrolyte streams.

[0094] In some instances, a contactor may comprise an extractor. In other instances, an extractor may comprise a membrane separator. In some instances, an extractor may comprise a micro- or nanostructured membrane. In some instances, a contactor may extract one or more chemical species from a feed stream. In some instances, a contactor may extract CO2from a feed stream. In some instances, a contactor may separate CO or CO2 from a feed stream and dissolve the CO or CO2 in an electrolyte solution. In some cases, a feed stream may be air. In some cases, the feed stream may be filtered prior to use. Such filtering may in some cases remove particulate matter and / or volatile organic materials and / or undesired materials of various kinds. The uptake of CO or C02 in a gas contactor may be enhanced by the presence of hydroxide ions generated within the electrochemical reduction system. The contactor(s) may be a membrane contactor(s), random or structured gas-liquid contacting packing such as film fill or splash packing, packed falling film device(s) such as a cooling tower, fluidized beds, shower(s) of liquid(s) in contact with gas(es), and the like. In some embodiments, the contactors may consist of nanostructured carbon materials such as carbon nanotube membranes, shown in FIG. 9. In some embodiments, the contactor 903 may be a carbon nanotube membrane 901 , shown in FIG. 9 and may have nanotubes 1002 functioning as pores, as shown in FIG. 10, and may have openings of the nanotubes 1102 functionalized with an adsorbing functional group 1104, such as an amine, shown in FIG. 11.

[0095] The present disclosure may provide reactor and separation systems that comprise micro- or nanostructured membranes. A micro- or nanostructured membrane may be utilized to perform a selective separation of one or more chemical species from a mixture comprising more than one chemical species. A micro- or nanostructured membrane may also provide additional utility in a chemical processing system including physically separating product streams and comprising a component of an electrical cathode or anode in an electrochemical system.

[0096] An electrochemical conversion system may comprise one or more unit operations for separations. Separation unit operations may include distillation columns, reactive distillation columns, gas absorption columns, stripping columns, additional catalysis operations, such as with catalyst packed columns, flash tanks, humidifiers, leaching units, liquid-liquid extraction units, dryers, adsorption systems, ion-exchange columns, membrane separation units, filtration units, sedimentation units, and crystallization units. A chemical conversion system may comprise one or more unit operations for heat transfer. Heat transfer unit operations may include mantle heaters, cartridge heaters, tape heaters, pad heaters, resistive heaters, radiative heaters, fan heaters, shell-and-tube heat exchangers, plate-type heat exchangers, extended- surface heat exchangers, scraped-surface heat exchangers, condensers, vaporizers, and evaporators. A chemical conversion system may comprise one or more unit operations for fluid transfer. Fluid transfer devices may include piping, tubing, fittings, valves, pumps, fans, blowers, compressors, stirrers, agitators, and blenders. Pumping equipment may be operated at pressures above atmospheric pressure or used to draw a vacuum. A chemical conversion system may comprise one or more chemical reaction units aside from an electrochemical reduction reactor. Chemical reaction units may include plug flow reactors, continuous-stirred tank reactors, packed bed columns, fluidized bed reactors, and batch reactors. Chemical reactors may be utilized for various upgrading and conversions including dehydrogenation, hydrogenation, cracking, dehydration, decarboxylation, carboxylation, amination, deamination, alkylation, dealkylation, oxidation, reduction, polymerization, and depolymerization.

[0097] An electrochemical conversion system comprising one or more micro- or nanostructured membranes may reduce or eliminate the energy consumption associated with one or more unit operations. For example, a gas separator comprising one or more micro- or nanostructured membranes may eliminate the need for a distillation column or separate adsorption system to separate CO or C02 from air. In some instances, the utilization of unit operations comprising micro- or nanostructured membranes may eliminate one or more pumps, compressors, heat exchangers, separators, or reactors from an electrochemical reduction system. The utilization of one or more micro-or nanostructured membranes may reduce the energy consumption of a processing step or processing 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. [0098] A micro- or nanostructured membrane may comprise one or more microscale or nanoscale materials features (e.g., including positive features, such as microscale or nanoscale structures, and/or negative features, such as microscale and nanoscale pores or microscale and nanoscale depressions). In some instances, a membrane may comprise carbon nanotubes, carbon nanospheres, carbon nano-onions, graphene-like materials, or pyrolyzed porous carbon materials (see FIG. 9 and FIG. 10). A membrane may comprise micro- or nanostructured material synthesized from non-carbon materials. A membrane may comprise carbon nanomaterials doped with other elements such as nitrogen, sulfur, and boron. A micro- or nanostructured material may be embedded, fixed, or otherwise bound to one or more other substrates or materials to construct a membrane. A micro- or nanostructured material embedded in a substrate or material may create pores within the structured membrane. The pores may permit the selective passage of certain chemical species. Other substrates or materials in the membrane may be selected for material properties including rigidity, strength, and/or electrical conductivity. Other substrates or materials in a micro- or nanostructured membrane may include polymers, e.g., polysulfones, metals, and ceramics. The microscale or nanoscale features may 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 larger. In some instances, the maximum dimension may be at most 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.

[0099] A micro- or nanostructured membrane may comprise a particular shape and/or structure depending upon its application. In some instances, a membrane may have a cylindrical structure (see FIG. 9 and FIG. 10), such as with a hollow fiber membrane format or have a substantially flat sheet structure. A membrane may partially or fully enclose a volume or void space. The surface area of a membrane disposed toward an enclosed or void space may be defined as a lumen side of the membrane. In some instances, mass transfer across a membrane may be driven by chemical potential, pressure difference, and/or temperature difference between a lumen side and a non-lumen side of a membrane. A membrane may further comprise additional structures such as frames or fittings that secure the membrane to other portions of the described systems.

[0100] A micro- or nanostructured membrane may be composed with micro- or nanomaterials embedded so as to create pores within the membrane. The micro- or nanomaterial may be chosen based upon a characteristic pore size that it may create. Without wanting to be bound by theory, a pore may be defined as a void space or volume within a solid material through which a liquid or gas molecule may flow or diffuse. A micro- or nanomaterial may have a characteristic length scale such as a diameter, (average) pore size, or layer spacing that is sufficient to permit the passage of chemical species through a void space in the material. In some instances, a 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 larger. In some instances, a characteristic length may be no more than about 5.0 nm, 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. A pore may have a larger diameter than length. A pore may have a larger length than diameter. A pore may have a length to width ratio of about 1:10, 1:5, 1:2, 1:1, 2:1, 5:1, 10:1, 100:1, or about 1000:1. A pore may have a length to width 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. A pore may have a length to width ratio of no more than about 1000:1, 100:1, 10:1, 5:1, 2:1, 1:1, 1:2, 1:5, or about 1 : 10 or less. A pore may comprise a substantially straight path such as a carbon nanotube or the space between layers of horizontal graphene-like materials. A pore may have a diagonal, skewed, or tortuous path in some materials, such as meso- or nanoporous carbons. [0101] A membrane may comprise a material with a characterized porous structure. Materials may include nanopores, mesopores, and micropores. In some instances, nanopores may be characterized as having an average diameter of about 2 nm or less. In some instances, mesopores may be characterized as having an average diameter of between about 2 nm and about 20 nm. In some instances, micropores may be characterized as having an average diameter of about 20 nm or more. A membrane may comprise structures with pore sizes across a range of pores sizes (e.g., nanopores and mesopores). A membrane may comprise structures with pores sizes from within a particular classification of pores sizes (e.g., only mesopores). A membrane may comprise pores (e.g., micropores or nanopores) with 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 (pm), or at least about 5 pm. A membrane may comprise pores with an average diameter of no more than about 5 pm, 1 pm, 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. A membrane comprising a micro- or nanostructured material may permit mass transport of one or more chemical species across the membrane. A membrane comprising a micro- or nanostructured material may be selective for particular species. In some instances, a membrane comprising micro- or nanostructured materials may selectively transfer CO2 from a gas stream. In some instances, a membrane comprising micro- or nanostructured materials may selectively transfer gaseous ethylene or ethanol from a gas mixture. In some instances, a membrane comprising micro- or nanostructured materials may selectively transfer hydrocarbons from an aqueous liquid mixture. A membrane comprising a micro- or nanostructured material may transfer particular chemical species by diffusive or convective mass transport. In some instances, mass transfer may be enhanced by the application of an external force or field. In particular instances, mass transfer may be driven or enhanced by the application of a magnetic or electrical field. In other instances, mass transfer may be driven by a pressure gradient (e.g. pulling a vacuum on one side of the membrane). In some instances, the selectivity of a membrane can be reversed by reversing an applied field or force. In other instances, a membrane may have a unidirectional or invariant mass transfer selectivity. A voltage bias may be present in some cases due to the electrochemical reduction process being performed. A voltage bias may be used to change the selectivity of a membrane, for example from being alcohol-selective to being water-selective. Magnetic fields can be present when electrical fields are present, and can be used to affect the concentration of ions. A magnetic field can be affected to favorably increase availability of reactants or intermediates at a catalyst surface.

[0102] The micro- or nanostructured membrane may have an optimal or preferred operation temperature and operation pressure. In some instances, a system comprising a micro- or nanostructured membrane may be operated at an ambient pressure or temperature. In some instances, a system comprising a micro- or nanostructured membrane may be operated at an elevated pressure or under a vacuum or reduced pressure. A pressure gradient may be utilized to drive mass transfer across a membrane system. A micro- or nanostructured membrane may be utilized in a system with 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. A micro- or nanostructured membrane may be utilized in a system with an operating temperature 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 about 80°C or more. A micro- or nanostructured membrane may be utilized in a system with an operating temperature of no more than about 80°C, 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 about -30°C or less.

[0103] A micro- or nanostructured membrane may be utilized in a system with an operating pressure 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. A micro- or nanostructured membrane may be utilized in a system with an operating pressure 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. A micro- or nanostructured membrane may be utilized in a system with an operating pressure of no more than about 50 bar, 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.

[0104] A micro- or nanostructured membrane may be capable of permitting a particular flux of CO2 across the membrane. A flux of CO2 may be driven by a pressure gradient across the membrane. In some instances, a pressure gradient may be driven by a gas stream comprising CO2 at a pressure elevated above ambient pressure. In other instances, a pressure gradient may exist by pulling a vacuum on one side of the membrane, e.g. the lumen side. A micro- or nanostructured membrane may permit a CO2 flux of about 0.1 kilogram gas/m ² of membrane/hr (kg/m ² /hr), 0.5 kg/m ² /hr, 1 kg/m ² /hr, 2 kg/m ² /hr, 3 kg/m ² /hr, 4 kg/m ² /hr, 5 kg/m ² /hr, 6 kg/m ² /hr, 7 kg/m ² /hr, 8 kg/m ² /hr, 9 kg/m ² /hr, or about 10 kg/m ² /hr. A micro- or nanostructured membrane may permit a CO2 flux of at least about 0.1kg/m ² /hr, 0.5 kg/m ² /hr,

1 kg/m ² /hr, 2 kg/m ² /hr, 3 kg/m ² /hr, 4 kg/m ² /hr, 5 kg/m ² /hr, 6 kg/m ² /hr, 7 kg/m ² /hr, 8 kg/m ² /hr, 9 kg/m ² /hr, or at least about 10 kg/m ² /hr. A micro- or nanostructured membrane may permit a CO2 flux of no more than about 10 kg/m ² /hr, 9 kg/m ² /hr, 8 kg/m ² /hr, 7 kg/m ² /hr, 6 kg/m ² /hr, 5 kg/m ² /hr, 4 kg/m ² /hr, 3 kg/m ² /hr, 2 kg/m ² /hr, 1 kg/m ² /hr, 0.5 kg/m ² /hr, or about 0.1 kg/m ² /hr or less.

[0105] A micro- or nanostructured membrane may be capable of permitting a particular flux of hydrocarbons across the membrane. A flux of hydrocarbons may be driven by a pressure gradient across the membrane. In some instances, a pressure gradient may be driven by a gas or liquid stream comprising hydrocarbons at a pressure elevated above ambient pressure. In other instances, a pressure gradient may exist by pulling a vacuum on one side of the membrane, e.g., the lumen side. A micro- or nanostructured membrane may permit a hydrocarbon flux of about 0.1 kilogram hydrocarbon/m ² of membrane/hr (kg/m ² /hr), 0.5 kg/m ² /hr, 1 kg/m ² /hr, 2 kg/m ² /hr, 3 kg/m ² /hr, 4 kg/m ² /hr, 5 kg/m ² /hr, 6 kg/m ² /hr, 7 kg/m ² /hr,

8 kg/m ² /hr, 9 kg/m ² /hr, or about 10 kg/m ² /hr. A micro- or nanostructured membrane may permit a hydrocarbon flux of at least about O.lkilogram kg/m ² /hr, 0.5 kg/m ² /hr, 1 kg/m ² /hr, 2 kg/m ² /hr, 3 kg/m ² /hr, 4 kg/m ² /hr, 5 kg/m ² /hr, 6 kg/m ² /hr, 7 kg/m ² /hr, 8 kg/m ² /hr, 9 kg/m ² /hr, or at least about 10 kg/m ² /hr. A micro- or nanostructured membrane may permit a hydrocarbon flux of no more than about 10 kg/m ² /hr, 9 kg/m ² /hr, 8 kg/m ² /hr, 7 kg/m ² /hr, 6 kg/m ² /hr, 5 kg/m ² /hr, 4 kg/m ² /hr, 3 kg/m ² /hr, 2 kg/m ² /hr, 1 kg/m ² /hr, 0.5 kg/m ² /hr, or about 0.1 kg/m ² /hr or less.

[0106] A membrane with an enhanced selectivity for one or more chemical species may enhance the chemical conversion rate or phase equilibrium of a conversion system. Without wanting to be bound to theory, selective enrichment for one or more chemical species within the void or pore space of the micro- or nanostructured component of a membrane may increase the volumetric concentration of the one or more chemical species within the void or pore space. In some instances, a kinetic rate enhancement or shift in phase equilibrium for a particular chemical reaction may be driven by one or more chemical species having higher volumetric concentrations within the membrane than may be predicted by their bulk phase concentrations on either side of the membrane. In a particular instance, the selective mass transfer of one or more chemical species through a membrane may cause an increased concentration of the one or more chemical species in a boundary layer adjacent to the surface of the membrane. An increase in the boundary layer concentration of the one or more chemical species may increase the availability of one or more chemical species to a catalyst deposited at the surface of the membrane. In another instance, a material sufficient to capture CO2with affinity for a target species may be part of the membrane surface or pore entrances and may enhance the concentration of the target species at the surface to facilitate selective transport, e.g., amines. In another instance, a catalyst may be deposited within the void or pore space of a micro- or nanostructured material within a membrane, allowing direct transfer of an increased mass transfer of one or more chemical species to the catalyst by bulk flow. [0107] The mass transfer selectivity of a membrane for one or more chemical species may cause a measurable enhancement of the rate of reaction for one or more chemical reactions in a chemical conversion system that comprises such a membrane. In some instances, the rate of reaction for 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 instances, the rate of reaction for one or more chemical reactions may be higher than may be predicted by the use of measured reactant concentrations due to other synergistic effects such as electric field enhancement of catalyst activity. In some instances, the mass transfer selectivity of a membrane for one or more chemical species may cause a measurable reduction in the rate of reaction for one or more chemical unwanted reactions (e.g., side reactions, degradation reactions) in a chemical conversion system that comprises such a membrane. In some instances, the rate of reaction for one or more unwanted chemical reactions may decrease by at least about 5%, 10%, 20%, 30%, 40%, 50%, 75%, 100%, 150%, 200%, 500%, or about 1000% or more.

[0108] A membrane comprising a micro- or nanostructured material may further comprise one or more catalyst materials. A catalyst material may be attached, bonded, deposited, or functionalized to the surface of a micro- or nanostructured material. In some instances, a catalyst may be located on a surface of a membrane. A catalyst may be localized in particular areas of a membrane or on particular areas of a micro- or nanostructured material to control where a catalyzed chemical reaction may occur. A catalyst may be located within a pore or pore-like structure in a membrane. A chemical reaction catalyzed by a catalyst may occur on a particular area of the membrane or within the pore or pore-like space of the membrane. A catalyst may comprise a metal atom, metal complex, or metal particle. A catalyst may comprise a metal 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 instances, a doped carbon nanomaterial may comprise a catalyst. In a particular instance, N-doped carbon nanotubes may comprise a catalyst. In another instance, carbon nanotubes with electrodeposited platinum, nickel, or copper nanoparticles may comprise a catalyst (see FIG. 11). A membrane may comprise more than one catalyst. In some instances, one or more catalysts may be deposited on one or more areas or surfaces of a membrane, and one or more differing catalysts may be deposited on one or more differing areas or surfaces of a membrane. A membrane may be capable of catalyzing one or more chemical reactions when mass transfer occurs in a particular direction across the membrane, and may be capable of catalyzing one or more differing chemical reactions when mass transfer occurs in a differing direction across the membrane.

[0109] An electrochemical reduction process utilizing a micro- or nanostructured catalyst membrane may utilize methods or components to minimize catalyst poisoning. A micro- or nanostructured membrane comprising a catalyst may be refreshed or regenerated to mitigate the impact of catalyst poisoning and the deposition of other unwanted species. In some instances, a membrane may be removed from an electrochemical reduction system for catalyst regeneration. In other instances, a membrane may be flushed with acid to dissolve or remove catalyst particles, followed thereafter by deposition of new catalyst particles on the membrane surface or nanoparticle surface. [0110] A membrane comprising a micro- or nanostructured material may have enhanced electrical properties. In some aspects, the membrane may be conductive, due to the electrical properties of the micro- or nanostructured materials. In some instances, a membrane may be semiconducting (e.g., carbon nanotubes of a particular chirality). A membrane may be configured to act as an electrode in an electrochemical system. A membrane may allow an electrical current to be conveyed to one or more catalysts associated with it. An electrical current may enhance the reactivity of a catalyst for particular catalyzed chemical reactions. In some instances, the selective mass transfer of particular chemical species across a micro- or nanostructured membrane may increase the current density achieved at the membrane electrode.

[0111] A membrane comprising a micro- or nanostructured material may be utilized for various purposes. In some instances, a membrane may permit mass transfer of a chemical species from a first gas mixture into a second gas mixture. In some instances, a membrane may permit mass transfer of a chemical species from a gas phase into a liquid phase. In some instances, a membrane may permit mass transfer of a chemical species from a first liquid mixture into a second liquid mixture. In some instances, a membrane may permit mass transfer of a chemical species to a catalytic site where a chemical reaction may occur. In some instances, a membrane may be utilized to perform both chemical separations and catalysis. In some instances, a membrane may be cycled between separation and catalysis by the directional application of electric fields or other fields or forces. In other instances, a membrane may be capable of simultaneously catalyzing and performing a chemical separation.

[0112] In some instances, heat exchangers and cooling or heating systems may be used to maintain desired temperatures in the various reservoirs, stack, or other unit elements. In some instances, the contactor unit, where the chemical reduction happens, may comprise a micro- or nanostructured membrane. The micro- or nanostructured membrane may comprise one or more catalysts. In other instances, a catalysis process may comprise a conventional electrochemical “stack”, comprising an anode and cathode within the same housing. In some instances, an ion exchange membrane may be used. In some instances, various catalytic membranes may be used, or otherwise achieve the desired reduction of CO2 by other methods of reduction. Oxygen or other oxidized species may also be produced by such a process and released to the atmosphere or directed to beneficial use.

[0113] Provided are example systems and methods for capturing and CO2, captured from air, using an electrolyte solution. [0114] Various embodiments of an integrated CO2 capture process that results in the dissolution of CO2 into an electrolyte may be conceived. In some instances, as depicted in FIG. 1, an electrolyte stream 102, containing an electrolyte solution for use in an electrochemical CO2 reduction process, may flow from a reservoir 101 to a contactor 103 where it is contacted with a CO2 containing gas. The CO2 containing gas may be air from the atmosphere. In some instances, the pH of the electrolyte stream 102 may be controlled such that CO2 is captured from the CO2 containing gas into the electrolyte solution. In some instances, the temperature of the electrolyte stream 102 may be controlled such that CO2 is absorbed from the CO2 containing gas into the electrolyte solution. After leaving the contactor 103, the electrolyte stream 110 may be directed to a second electrolyte reservoir 108. In some instances, 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 may be controlled particularly to facilitate the capture of water. Water may be a reactant in the conversion of CO2 into hydrocarbons, so water may be supplied to the reaction from different sources, such as by capture with CO2 from the air and/or from another source. Decreasing the temperature of the absorbing fluid below the dew point of the CO2-containing gas source (e.g., air) can result in the simultaneous capture of water due to condensation from the air.

[0115] In another example, depicted in FIG. 2, an electrolyte stream 202, containing an electrolyte solution for use in an electrochemical CO2 reduction process, may be directed from an electrolyte reservoir 201 to a pH controlling unit 204. The pH of the electrolyte stream 202 may be adjusted to facilitate CO2 capture. The pH controlling unit 204 may increase the pH of the electrolyte stream 202 to between 10 - 15. For example, stream 211 may have a pH of about 10, 11, 12, 13, 14, or 15 after passing the pH controlling unit 204. In some instances, the electrolyte stream 211 may enter a contactor 203 where it is contacted with a CO2 containing fluid. In some instances, the CO2 containing fluid is the atmospheric air. The capture of CO2 in the contactor 203 may cause the pH of the electrolyte to be reduced to between 7 - 9. For example, stream 210 may have a pH of about 7, 8, or 9 after capture of CO2 in the contractor 203. After leaving the contactor 203, the electrolyte stream 210 may continue to a second electrolyte reservoir 208. In some instances, the CO2 containing gas also contains water which may also be absorbed. In some instances, the temperature of the electrolyte stream(s) or any other component of the contactor 203 may be controlled particularly to facilitate the capture of water. In some embodiments, CO2 is reduced in the pH controlling unit. In some embodiments, the pH controlling unit is in a separate housing than the contactor. In some embodiments, the pH controlling unit and contactor are in the same housing. In some embodiments, the housing comprises multiple compartments or chambers. In some embodiments, the pH controlling unit is in a compartment or chamber separate from the compartment or chamber comprising the contactor. In some embodiments, the pH controlling unit is in the same chamber as the contactor. In some embodiments, the pH controlling unit is comprised within a membrane. [0116] In another example, depicted in FIG. 3, an electrolyte stream 302, containing an electrolyte solution for use in an electrochemical CO2 reduction process, may be directed from an electrolyte reservoir 301 to a pH controlling unit 304. The pH of the electrolyte stream 302 may be adjusted to facilitate CO2 capture. The pH controlling unit 304 may adjust the pH of the electrolyte stream to between 10 - 15. For example, stream 311 may have a pH of about 10, 11, 12, 13, 14, or 15 after passing the pH controlling unit 304. In some instances, the electrolyte stream 311 may enter a contactor 303 where it is contacted with a CO2 containing fluid. In some instances, the CO2 containing fluid is the atmosphere. After leaving the contactor 303, the electrolyte stream 312 may continue to a second pH controlling unit

307. The pH of the electrolyte stream 312 may be adjusted to facilitate CO2 reduction. The second pH controlling unit 307 may adjust the pH of the electrolyte stream to between 7 - 10. For example, stream 310 may have a pH of about 7, 8, 9, or 10 after capture of CO2 in the contractor 307. The electrolyte stream 310 may continue to a second electrolyte reservoir

308. In some instances, the CO2 containing gas also contains water which may also be absorbed. In some instances, the temperature of the electrolyte stream or any other component of the contactor 303 may be controlled particularly to facilitate the capture of water. In some embodiments, CO2 is reduced in the pH controlling unit. In some embodiments, the electrolyte stream 310 may also contain a reduced carbon product. In some embodiments, the reduced carbon product is separated from the electrolyte stream 310. In some embodiments, the electrolyte stream 310 may be reused in the electrochemical reduction system. In some embodiments, the pH controlling unit is in a separate housing than the contactor. In some embodiments, the pH controlling unit and contactor are in the same housing. In some embodiments, the housing comprises multiple compartments or chambers. In some embodiments, the pH controlling unit is in a compartment or chamber separate from the compartment or chamber comprising the contactor. In some embodiments, the pH controlling unit is in the same chamber as the contactor. In some embodiments, the pH controlling unit is comprised within a membrane. [0117] In another example, depicted in FIG. 4, an electrolyte stream 402, containing an electrolyte solution for use in an electrochemical CO2 reduction process, may be directed from an electrolyte reservoir 401 to a pH controlling unit 406. The pH controlling unit 406 may adjust the pH of electrolyte stream 402 to facilitate CO2 capture. The pH controlling unit 406 may adjust the pH of the electrolyte stream to between 10 - 15. For example, stream 411 may have a pH of about 10, 11, 12, 13, 14, or 15 after passing the pH controlling unit 406. In some instances, the electrolyte stream 411 may enter a contactor 403 where it is contacted with a CO2 containing fluid. In some instances, the CO2 containing fluid is the atmosphere. After leaving the contactor 403, the electrolyte stream 412 may reenter the pH controlling unit 406. The pH controlling unit 406 may adjust the pH of the electrolyte stream 412 to facilitate CO2 reduction. The pH controlling unit 406 may adjust the pH of the electrolyte stream to between 7 - 10. Stream 410 may have a pH of about 7, 8, 9, or 10 after passing the pH controlling unit 406. The electrolyte stream 410 may continue to a second electrolyte reservoir 408. In some instances, the CO2 containing gas also contains water which may also be absorbed. In some instances, the temperature of the electrolyte stream or any other component of the contactor 403 may be controlled particularly to facilitate the capture of water. The pH controlling unit 406 may be a bipolar membrane stack or electrochemical stack that may cause one input stream 402 to raise in pH and the other input stream 412 to lower in pH. 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 controlling unit 406 may be an electrochemical stack that may reduce CO2 _. CO2 may be captured in the electrolyte stream 412 and be in the form of bicarbonate or carbonate ions. The reduction reaction, which may take place in the electrochemical stack 406, may produce hydroxide ions. The hydroxide ions may diffuse through the anion exchange layer of the membrane stack and migrate towards the anode. The anode may be in contact with the input electrolyte stream 402. The hydroxide ions may be added to stream 402. The addition of hydroxide ions may raise the pH of stream 402. and decrease the pH of stream 412. In some embodiments, the electrolyte stream 410 may also contain a reduced carbon product. In some embodiments, the reduced carbon product is separated from the electrolyte stream 410. In some embodiments, the electrolyte stream 410 may be reused in the electrochemical reduction system. This electrochemical stack 406 may not be optimized for CO2 reduction, but rather for pH adjustment. In some embodiments, CO2 is reduced in the pH controlling unit. In some embodiments, the pH controlling unit is in a separate housing than the contactor. In some embodiments, the pH controlling unit and contactor are in the same housing. In some embodiments, the housing comprises multiple compartments or chambers. In some embodiments, the pH controlling unit is in a compartment or chamber separate from the compartment or chamber comprising the contactor. In some embodiments, the pH controlling unit is in the same chamber as the contactor. In some embodiments, the pH controlling unit is comprised within a membrane.

[0118] In another example, depicted in FIG. 5, an electrolyte stream 502, containing an electrolyte solution for use in an electrochemical CO ₂ reduction process, may be directed from an electrolyte reservoir 501 to a pH controlling unit 504. The pH of the electrolyte stream 502 may be adjusted to facilitate CO ₂ capture. In some instances, after passing the pH controlling unit 504, the electrolyte stream 511 may enter a contactor 503 where it is contacted with a CO ₂ containing fluid. In some instances, the CO ₂ containing fluid is the atmosphere. After leaving the contactor 503, the electrolyte stream 512 may continue to a second pH controlling unit 507. In some embodiments, CO ₂ is reduced in the pH controlling unit 507. In some embodiments, the electrolyte stream 510 may also contain 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 may be reused in the electrochemical reduction system. The pH of the electrolyte stream 512 may be adjusted to facilitate CO ₂ reduction. After the passing the pH controlling unit 507, the electrolyte stream 510 may continue to a second electrolyte reservoir 508. A separate method of creating acid and base streams 509 may be used to create acid 513 and base 514 which are used to adjust pH in the pH controlling unit 507 and 504, respectively. In some instances, the CO ₂ containing gas also contains water which may also be absorbed. In some instances, the temperature of the electrolyte stream or any other component of the contactor 503 may be controlled particularly to facilitate the capture of water. In some embodiments, CO ₂ is reduced in the pH controlling unit. In some embodiments, the pH controlling unit is in a separate housing than the contactor. In some embodiments, the pH controlling unit and contactor are in the same housing. In some embodiments, the housing comprises multiple compartments or chambers. In some embodiments, the pH controlling unit is in a compartment or chamber separate from the compartment or chamber comprising the contactor. In some embodiments, the pH controlling unit is in the same chamber as the contactor. In some embodiments, the pH controlling unit is comprised within a membrane. [0119] In another example, depicted in FIG. 6, an electrolyte stream 602, containing an electrolyte solution for use in an electrochemical CO ₂ reduction process, may flow from a reservoir 601 to a contactor 605 where it is contacted with a CO ₂ containing gas. The CO ₂ containing gas may be the atmosphere. In some instances, the pH of the electrolyte stream 602 may be controlled such that CO2 is captured from the CO2 containing gas into the electrolyte solution. In some instances, the temperature of the electrolyte stream 602 may be controlled such that CO2 is captured from the CO2 containing gas into the electrolyte solution. The contactor 605 may include a material to facilitate the capture of CO2 from the CO2 containing gas. In some embodiments, that material is a solid adsorbent. In some instances, the material is a solid substrate for reactive chemical adsorbents. One example of such a material is polystyrene beads functionalized with amines. Another example is activated or nanostructured carbon materials such as carbon nanotubes, Buckminster fullerene, or graphene. After leaving the contactor 605, the electrolyte stream 610 may proceed to a second electrolyte reservoir 608. In some instances, 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 particularly to facilitate the capture of water.

[0120] In another example, depicted in FIG. 7, an electrolyte stream 702, containing an electrolyte solution for use in an electrochemical CO2 reduction process, may be directed from an electrolyte reservoir 701 to a pH controlling unit 706. The pH of the electrolyte stream 702 may be adjusted to facilitate CO2 capture. The pH controlling unit 706 may adjust the pH of the electrolyte stream to between 10 - 15. Stream 711 may have a pH of about 10, 11, 12, 13, 14, or 15 after passing the pH controlling unit 706. In some instances, the pH- adjusted electrolyte stream 711 may enter a contactor 703 and may be contacted with a liquid material sufficient for capture of CO2. The liquid material may be an aqueous hydroxide solution, an amine solution, an ionic liquid, or any other liquid material sufficient for capture of CO2 . The lean CO2 capturing liquid 715 may leave the contactor 703 and be directed to a contactor 705 where it may be contacted with a CO2 containing fluid. The CO2 containing fluid may be the atmosphere. The CO2 rich capturing liquid 716 may leave the contactor 705 and be directed to the contactor 703 where it may be contacted with the electrolyte stream 711. The CO2 enriched electrolyte stream 712 may leave the contactor 703 and be directed to a pH controlling unit 706. The pH of the electrolyte stream 712 may be optimized to facilitate CO2 reduction. The pH controlling unit 706 may adjust the pH of the electrolyte stream to between 7 - 10. For example, stream 710 may have a pH of about 7, 8, 9, or 10 after passing the pH controlling unit 706. The pH-adjusted electrolyte stream 710 may continue to a second electrolyte reservoir 708. In some embodiments, the electrolyte stream 710 may also contain a reduced carbon product. In some embodiments, the reduced carbon product is separated from the electrolyte stream 710. In some embodiments, the electrolyte stream 710 may be reused in the electrochemical reduction system. In some instances, the CO ₂ containing gas also contains water which may also be absorbed. In some instances, the temperature of the electrolyte stream or any other component of the contactor 703 may be controlled particularly to facilitate the capture of water. The pH controlling unit 706 may be a bipolar membrane stack or electrochemical stack that may cause one input stream 702 to raise in pH and the other input stream 712 to lower in pH. 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 controlling unit 706 may be an electrochemical stack that may reduce CO _2. The CO ₂ may be captured in the electrolyte solution and 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 towards the anode, raisingthe pH of stream 702 and decreasing the pH of stream 712. This electrochemical stack 706 may not be optimized for CO ₂ reduction, but rather for pH adjustment. In some embodiments, CO ₂ is reduced in the pH controlling unit. In some embodiments, the pH controlling unit is in a separate housing than the contactor. In some embodiments, the pH controlling unit and contactor are in the same housing. In some embodiments, the housing comprises multiple compartments or chambers. In some embodiments, the pH controlling unit is in a compartment or chamber separate from the compartment or chamber comprising the contactor. In some embodiments, the pH controlling unit is in the same chamber as the contactor. In some embodiments, the pH controlling unit is comprised within a membrane.

[0121] In another example, depicted in FIG. 8, an electrolyte stream 802, containing an electrolyte solution for use in an electrochemical CO ₂ reduction process, may be directed from an electrolyte reservoir 801 to a contactor 805 where it may be contacted with a liquid material sufficient for capturing CO ₂ . The liquid material may be an aqueous hydroxide solution, an amine solution, an ionic liquid, or any other liquid material. The lean CO ₂ capturing liquid 811 may leave the contactor 805 and be directed to a contactor 803 where it may be contacted with a CO ₂ containing fluid. The CO ₂ containing fluid may be the atmosphere. The CO ₂ rich capturing liquid 812 may leave the contactor 803 and be directed to the contactor 805 where it may be contacted with the electrolyte stream 802. The CO ₂ enriched electrolyte stream 810 may leave the contactor 805 and continue to a second electrolyte reservoir 808. In some instances, the CO ₂ containing gas also contains water which may also be absorbed. In some instances, the temperature of the electrolyte stream or any other component of the contactor 805 may be controlled particularly to facilitate the capture of water. The contactor 805 may be a bipolar membrane stack containing 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 the transport of carbon- containing species from the CO2 rich capturing liquid 812 to the electrolyte stream 802. The contactor 805 may also adjust the pH of input streams 802 and 812.

[0122] In some embodiments, a contactor, a pH controlling unit, and an electrochemical reduction system comprising the anode and the cathode may be in the same housing. In some embodiments, a contactor may be in a separate housing from the pH controlling unit and the electrochemical reduction system comprising the anode and the cathode. In some embodiments, the pH controlling unit and the electrochemical reduction system comprising the anode and the cathode may be within the same housing. In some embodiments, the contactor, the pH controlling unit, and the electrochemical reduction system comprising the anode and the cathode may be housed in separate housings. In some embodiments, the electrochemical reduction system comprising the anode and the cathode may further comprise additional chambers or compartments that house the anode, the cathode, voltage source, membrane, or a combination thereof.

Computer systems

[0123] The present disclosure provides computer systems that are programmed to implement methods of the disclosure. FIG. 12 shows a computer control system 1201 that is programmed or otherwise configured to control a chemical reduction system or a process within a 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, methods of producing a reduced carbon product or monitoring for potentially hazardous operating conditions. The computer control system 1201 can be implemented on an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

[0124] The computer system 1201 includes a central processing unit (CPU, also “processor” and “computer processor” herein) 1205, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 1201 also includes memory or memory location 1210 (e.g., random-access memory, read-only memory, flash memory), electronic storage unit 1215 (e.g., hard disk), communication interface 1220 (e.g., network adapter) for communicating 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, storage unit 1215, interface 1220 and peripheral devices 1225 are in communication with the CPU 1205 through a communication bus (solid lines), such as a motherboard. The storage unit 1215 can be a data storage unit (or data repository) for storing data. The computer system 1201 can be operatively coupled to a computer network (“network”) 1230 with the aid of the communication interface 1220. The network 1230 can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. The network 1230 in some cases is a telecommunication and/or data network. The network 1230 can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network 1230, in some cases with the aid of the computer system 1201, can implement a peer-to-peer network, which may enable devices coupled to the computer system 1201 to behave as a client or a server.

[0125] The CPU 1205 can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 1210. The instructions can be directed to the CPU 1205, which can subsequently program or otherwise configure the CPU 1205 to implement methods of the present disclosure. Examples of operations performed by the CPU 1205 can include fetch, decode, execute, and writeback.

[0126] The CPU 1205 can be part of a circuit, such as an integrated circuit. One or more other components of the system 1201 can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

[0127] The storage unit 1215 can store files, such as drivers, libraries and saved programs. The storage unit 1215 can store user data, e.g., user preferences and user programs. The computer system 1201 in some cases 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 is in communication with the computer system 1201 through an intranet or the Internet.

[0128] The computer system 1201 can communicate with one or more remote computer systems through the network 1230. For instance, 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 personal computers (e.g., portable PC), slate or tablet PC’s (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user can access the computer system 1201 via the network 1230 [0129] Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 1201, such as, for example, on the memory 1210 or electronic storage unit 1215. The machine executable or machine readable code can be provided in the form of software.

During use, the code can be executed by the processor 1205. In some cases, the code can be retrieved from the storage unit 1215 and stored on the memory 1210 for ready access by the processor 1205. In some situations, the electronic storage unit 1215 can be precluded, and machine-executable instructions are stored on memory 1210.

[0130] The code can be pre-compiled and configured for use with a machine having a processor adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a pre-compiled or as-compiled fashion.

[0131] Aspects of the systems and methods provided herein, such as the computer system 1201, can be embodied in programming. Various aspects of the technology may be thought of as “products” or “articles of manufacture” typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machine-executable code can be stored on an electronic storage unit, such as memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. “Storage” type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non- transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted 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. [0132] Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform.

Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise 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 therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting 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.

[0133] The computer system 1201 can include or be in communication with an electronic display 1235 that comprises a user interface (EΊ) 1240 for providing, for example, the pH and/or temperature of electrolyte streams. Examples of UFs include, without limitation, a graphical user interface (GET) and web-based user interface.

[0134] Methods and systems of the present disclosure can be implemented by way of one or more algorithms. An algorithm can be implemented by way of software upon execution by the central processing unit 1205. The algorithm can, for example, regulate the flow rate of a gas stream comprising CO ₂ through a contactor to optimize the pH or bicarbonate concentration of an electrolyte solution. As another example, the algorithm can regulate the electric field applied to a micro- or nanostructured membrane to control the selectivity of the membrane for a particular chemical species.

[0135] EXAMPLE: Conversion of CO2 to Ethanol

[0136] In an example, CO ₂ is captured from an input air stream and reduced to ethanol. In this example, an input air stream comprising CO ₂ is directed into the contactor of an electrochemical reduction system. An electrolyte solution may also be directed into the contactor. The electrolyte solution may comprise water. Upon contacting the air stream with water, CO2 may react with water to form bicarbonate and hydronium ions, by way of carbonic acid. At this point, CO2 may be captured by a water molecule as a bicarbonate ion.

A stream of water, including bicarbonate ions, is directed to a compartment comprising a membrane and voltage source. Bicarbonate ions are converted to form ethanol and hydroxide ions when a voltage is applied (e.g., reduction). In some cases, the reduced carbon product, ethanol, may pass through the membrane in order to be separated from unreacted bicarbonate ions and hydroxide ions, among other species. Upon passage of reduced carbon product through the membrane, the pH of the solution on the original side of the membrane may increase. The increase in pH may facilitate conversion of unreacted bicarbonate ions into carbonate ions and water. Additionally, the solution with increased pH may further facilitate capture of CO2 from an input air stream into water. As such, through generation of water and/or hydroxide ions, the electrolyte is regenerated and may be used to repeat the cycle of carbon dioxide capture and reduction one or more times.

[0137] Methods and systems of the present disclosure may be combined with or modified by other methods and systems, such as, for example, those disclosed in U.S. Patent No. 10,590,548 and WO/2020/131837, each of which is entirely incorporated herein by reference.

[0138] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.