Selectable fuel compositions

Abstract

Described herein are methods for generating fuel compositions through electrochemical reduction of carbon dioxide, or carbon containing material, where the resulting mixture of hydrocarbons in the fuel composition have a mean number carbon atoms and at least 50% of the hydrocarbons in the mixture have a number of carbon atoms that is within 5 carbon atoms of the mean number. Also described herein are methods for identifying a source of a fuel composition measuring a carbon isotope signature of the fuel composition.

Description

WSGR Docket No.56520-706.601 SELECTABLE FUEL COMPOSITIONS CROSS REFERENCE

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 600,428, filed November 17, 2023, the entire content of which is incorporated herein. BACKGROUND

[0002] Various types of reduced carbon products may be generated from the electrochemical reduction of carbon dioxide (“CO2”) including but not limited to alcohols, aldehydes, ketones, and linear, branched, and cyclic alkanes and alkenes. In some cases, reduced carbon products can be useful products, including transportation fuels and polymers. SUMMARY

[0003] The present disclosure provides systems and methods for generating fuel compositions.

[0004] In one aspect, provided herein is a method for generating a fuel composition, comprising: (a) contacting a gaseous stream comprising carbon dioxide (CO2) with an electrolyte solution to capture at least a subset of the CO2 into the electrolyte solution, thereby obtaining an electrolyte solution comprising captured CO2; and (b) in an electrochemical reduction system, reducing the captured CO2 to generate a fuel composition comprising a mixture of hydrocarbons, wherein at least 50% of hydrocarbons in the mixture comprise a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the fuel composition.

[0005] In another aspect, provided herein is a method for generating a fuel composition, comprising: (a) receiving a request for the fuel composition; and (b) in an electrochemical reduction system, reducing carbon dioxide (CO2) to generate the fuel composition comprising a mixture of hydrocarbons, wherein at least 50% of hydrocarbons in the mixture comprise a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the fuel composition, thereby fulfilling the request. In some embodiments, the request specifies the mean number of carbon atoms in the fuel composition.

[0006] In some embodiments, the mean number of carbon atoms in the fuel composition is from about 1 to about 40. In some embodiments, the mean number of carbon atoms in the fuel composition is from about 2 to about 13. In some embodiments, the meanWSGR Docket No.56520-706.601 number of carbon atoms in the fuel composition is from about 8 to about 20. In some embodiments, the mean number of carbon atoms in the fuel composition is from about 12 to about 24. In some embodiments, the mean number of carbon atoms in the fuel composition is from about 20 to about 32. In some embodiments, the mean number of carbon atoms in the fuel composition is from about 18 to about 34.

[0007] In some embodiments, at least 70% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition. In some embodiments, at least 80% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition. In some embodiments, at least 90% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition.

[0008] In some embodiments, at least 50% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition. In some embodiments, at least 50% of hydrocarbons in the mixture are within 1 carbon atoms of the mean number of carbon atoms in the fuel composition.

[0009] In some embodiments, the electrochemical reduction system comprises an electrochemical stack. In some embodiments, the electrochemical stack comprises a surface area. In some embodiments, the surface area of the electrochemical stack has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a larger surface area yields a higher mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical stack comprising a smaller surface area.

[0010] In some embodiments, the electrochemical reduction system operates under a set of one or more parameters selected from the group consisting of: a composition of the electrolyte solution, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, a distance between active sites on a catalyst in the electrochemical reduction system, a residence time of the captured CO2 in the electrochemical reduction system, a voltage applied to the electrochemical reduction system, a pH of the electrolyte solution, and a concentration of total inorganic carbon (TIC) in the electrolyte solution.

[0011] In some embodiments, at least one parameter of the one or more parameters are selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.WSGR Docket No.56520-706.601

[0012] In some embodiments, the at least one parameter comprises the temperature of the electrochemical reduction system. In some embodiments, the temperature of the electrochemical reduction system is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms. In some embodiments, the temperature of the electrochemical reduction system has a negative correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher temperature yields a smaller mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical reduction stack operating at a relatively lower temperature.

[0013] In some embodiments, the at least one parameter comprises the distance between active sites on the catalyst in the electrochemical reduction system. In some embodiments, the distance between active sites on the catalyst in the electrochemical reduction system is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms. In some embodiments, the distance between active sites on the catalyst in the electrochemical reduction system has a negative correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a catalyst comprising a relatively shorter distance between active sites yields a larger mean carbon atom number in the fuel composition than an otherwise similar catalyst comprising a relatively longer distance between active sites.

[0014] In some embodiments, the catalyst composition comprises copper, nickel, platinum, iridium, ruthenium, palladium, tin, silver, or gold.

[0015] In some embodiments, the at least one parameter comprises the residence time of the captured CO2 in the electrochemical reduction system. In some embodiments, the residence time of the captured CO2 in the electrochemical reduction system is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms. In some embodiments, the residence time of the captured CO2 in the electrochemical reduction system has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively shorter residence time of the captured CO2 in the electrochemical reduction system yields a smaller mean carbon atom number in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively longer residence time.

[0016] In some embodiments, the at least one parameter comprises the voltage applied to the electrochemical reduction system. In some embodiments, the voltage is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms. In someWSGR Docket No.56520-706.601 embodiments, the voltage applied to the electrochemical reduction system has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher voltage yields a larger mean carbon atom numbers in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively lower voltage.

[0017] In some embodiments, the at least one parameter comprises the pH of the electrolyte solution. In some embodiments, the pH of the electrolyte solution is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.In some embodiments, the pH of the electrolyte solution has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher pH of the electrolyte solution yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively lower pH.

[0018] In some embodiments, the at least one parameter comprises the concentration of the TIC in the electrolyte solution. In some embodiments, the concentration of the TIC in the electrolyte solution is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms. In some embodiments, the concentration of the TIC in the electrolyte solution has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher concentration of TIC yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively lower concentration of TIC.

[0019] In some embodiments, the electrolyte solution comprising captured CO2 comprises carbonate ions, bicarbonate ions, or a combination thereof. In some embodiments, the captured CO2 comprises bicarbonate ions.

[0020] In some embodiments, the electrolyte solution comprises water. In some embodiments, the electrolyte solution further comprises a potassium ion, sodium ion, or a combination thereof.

[0021] In some embodiments, the gaseous stream comprises CO2 from an atmosphere (e.g., ambient air) or a biological process or an industrial process. In some embodiments, the gaseous stream comprising CO2 comprises air.

[0022] In some embodiments, the fuel composition is obtained in absence of distillation.

[0023] In another aspect, provided herein is a method for identifying a source of a fuel composition, comprising measuring a carbon isotope signature of the fuel composition,WSGR Docket No.56520-706.601 wherein the carbon isotope signature indicates whether the source comprises atmospheric CO2.

[0024] In some embodiments, the carbon isotope signature comprises (i) a ratio of 12C isotope to 13C isotope in the fuel composition, (ii) a concentration of 13C isotope in the fuel composition, or (iii) a concentration of 14C isotope in the fuel composition.

[0025] In some embodiments, the carbon isotope signature comprises a ratio of 12C isotope to 13C isotope in the fuel composition. In some embodiments, the carbon isotope signature comprises a concentration of 13C isotope in the fuel composition. In some embodiments, the carbon isotope signature comprises a concentration of 14C isotope in the fuel composition.

[0026] In some embodiments, the carbon isotope signature indicates whether the source is a fossil fuel or biofuel. In some embodiments, the carbon isotope signature indicates whether the fuel composition is a carbon neutral fuel.

[0027] In some embodiments, the measuring occurs onboard a vehicle configured to operate on the fuel composition. In some embodiments, the measuring occurs at a pump configured to dispense the fuel composition.

[0028] 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

[0029] 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.WSGR Docket No.56520-706.601 BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The novel features of the systems and methods described herein are set forth with particularity in the appended claims. A better understanding of the features and advantages of the systems and methods described herein will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the systems and methods described herein are utilized, and the accompanying drawings (also “Figure” and “FIG.” herein) of which:

[0031] FIG.1 illustrates a schematic diagram of a method for generating a fuel composition using an electrochemical reduction stack, in accordance with some embodiments.

[0032] FIG.2 illustrates an additional schematic diagram of a method for generating a fuel composition in the absence of an electrochemical reduction stack, in accordance with some embodiments.

[0033] FIG.3 shows a computer system that is programmed or otherwise configured to implement methods provided herein. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] 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.WSGR Docket No.56520-706.601

[0037] As used herein, the term “about” generally refers to within ±1%, 5%, of 10% of a value. For example, if it is stated, “a temperature of about 100 degrees Celsius”, it can be implied that the temperature may be from 90°C to 110°C.

[0038] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and / or” unless the content clearly dictates otherwise.

[0039] 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 (C1), two carbon atoms (C2), etc. C1+ compounds include, without limitation, alkanes (e.g., methane, CH4), alkenes (e.g., ethylene, C2H2), alkynes and aromatics containing two or more carbon atoms. In some cases, C1`+ 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 (RCP) or reduced carbon material, as used herein. In some embodiments, a C1+ product or an RCP comprises a hydrocarbon.

[0040] The term “hydrocarbon” as used herein, generally refers to a compound comprising carbon atoms and hydrogen atoms. Hydrocarbons may include alkanes, alkenes, alkynes, and / or aromatic compounds. A hydrocarbon may comprise one or more carbon atoms (e.g., C1 to C40).

[0041] The term “fuel composition” as used herein, generally refers to a solution comprising one or more hydrocarbons. A fuel composition may comprise a mixture of hydrocarbons.

[0042] 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).

[0043] The term “carbon-containing material,” as used herein, generally refers to any material comprising at least one carbon atom. In some examples, 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 asWSGR Docket No.56520-706.601 bicarbonate or bicarbonate ions. Provided herein are systems, devices, and methods for the electrochemical reduction of CO2into fuel compositions comprising one or more hydrocarbons. 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, and organic acids. Additionally, hydrocarbons with longer chain lengths, may have a high a potential for conversion to useful products, including transportation fuels and polymers. A longer chain hydrocarbon can be produced from the electrochemical reduction of CO2. The carbon length of the hydrocarbon can be modified by selecting or adjusting one or more parameters of the electrochemical reduction system or method.

[0044] In one aspect, provided herein is a method for generating a fuel composition, comprising: (a) contacting a gaseous stream comprising carbon dioxide (CO2) with an electrolyte solution to capture at least a subset of the CO2into the electrolyte solution, thereby obtaining an electrolyte solution comprising captured CO2; and(b) in an electrochemical reduction system, reducing the captured CO2to generate a fuel composition comprising a mixture of hydrocarbons, wherein at least 50% of hydrocarbons in the mixture comprise a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the fuel composition.

[0045] In one aspect, provided herein is a method for generating a fuel composition, comprising: (a) receiving a request for the fuel composition; and (b) in an electrochemical reduction system, reducing carbon dioxide (CO2) to generate the fuel composition comprising a mixture of hydrocarbons, wherein at least 50% of hydrocarbons in the mixture comprise a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the fuel composition, thereby fulfilling the request. In some cases, the CO2is captured in an electrolyte solution prior to the reducing in (b).

[0046] An electrochemical reduction system for the conversion of CO2into other chemicals may comprise various components to facilitate the reduction of CO2. In some instances, an electrochemical reduction system may be referred to as a chemical conversion system. Components may include electrochemical stacks, cathodes, anodes, contactors, extractors, pumps, vapor-liquid separators (e.g., micro- or nanostructured membranes), and ion exchange membranes. In some embodiments, an electrochemical reduction system comprises an electrochemical stack. In some embodiments, an electrochemical reduction system comprises a cathode and an anode. In some embodiments, an electrochemicalWSGR Docket No.56520-706.601 reduction system comprises a cathode, an anode, and an ion-exchange membrane, In some embodiments, the cathode comprises a catalyst. 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.

[0047] An electrochemical reduction system may comprise a cathode, an anode and an electrolyte solution that collectively provide the necessary components for the reduction of carbon dioxide to other chemical species. The electrolyte may comprise an aqueous salt solution that is composed with an optimal ionic strength and pH for the electrochemical reduction of CO or CO2. An electrolyte may comprise an aqueous salt solution comprising bicarbonate and / or carbonate ions. In some embodiments, the electrolyte comprises an aqueous salt comprising bicarbonate and / or carbonate ions in proportion to a specific pH. In some instances, an electrolyte may comprise an aqueous solution of sodium bicarbonate and / or sodium carbonate or potassium bicarbonate and / or potassium carbonate. In some embodiments, the electrolyte solution comprises water. In some embodiments, the electrolyte solution comprises an aqueous solution comprising potassium ions, sodium ions, or a combination thereof. In some instances, bicarbonate ions and / or carbonate ions may dissociate in the presence of one or more catalysts to produce CO or CO2molecules for a reduction reaction.In some instances, bicarbonate ion and / or carbonate ions are reduced directly to reduced carbon products. The dissolution of CO or CO2into the electrolyte solution may regenerate or maintain the optimal concentration of bicarbonate ions and / or carbonate ions (to achieve a specific pH, carbon concentration, and / or ionic strength) for the production of a fuel composition.

[0048] An electrochemical reduction system may be configured to operate at an optimal voltage for the reduction of CO or CO2to reduced products. An electrochemical reduction system may be arranged in a stack or series configuration to tailor the system voltage to an optimal value. In some embodiments, an electrochemical reduction system may have an operating voltage of about 2 volts (V) to about 6 V.

[0049] An electrochemical reduction system may have an operating voltage of about 2 volts (V) to about 3 V. An electrochemical reduction system may have an operating voltageWSGR Docket No.56520-706.601 of about 2 V to about 2.1 V, about 2 V to about 2.2 V, about 2 V to about 2.3 V, about 2 V to about 2.4 V, about 2 V to about 2.5 V, about 2 V to about 2.6 V, about 2 V to about 2.7 V, about 2 V to about 2.8 V, about 2 V to about 2.9 V, about 2 V to about 3 V, about 2.1 V to about 2.2 V, about 2.1 V to about 2.3 V, about 2.1 V to about 2.4 V, about 2.1 V to about 2.5 V, about 2.1 V to about 2.6 V, about 2.1 V to about 2.7 V, about 2.1 V to about 2.8 V, about 2.1 V to about 2.9 V, about 2.1 V to about 3 V, about 2.2 V to about 2.3 V, about 2.2 V to about 2.4 V, about 2.2 V to about 2.5 V, about 2.2 V to about 2.6 V, about 2.2 V to about 2.7 V, about 2.2 V to about 2.8 V, about 2.2 V to about 2.9 V, about 2.2 V to about 3 V, about 2.3 V to about 2.4 V, about 2.3 V to about 2.5 V, about 2.3 V to about 2.6 V, about 2.3 V to about 2.7 V, about 2.3 V to about 2.8 V, about 2.3 V to about 2.9 V, about 2.3 V to about 3 V, about 2.4 V to about 2.5 V, about 2.4 V to about 2.6 V, about 2.4 V to about 2.7 V, about 2.4 V to about 2.8 V, about 2.4 V to about 2.9 V, about 2.4 V to about 3 V, about 2.5 V to about 2.6 V, about 2.5 V to about 2.7 V, about 2.5 V to about 2.8 V, about 2.5 V to about 2.9 V, about 2.5 V to about 3 V, about 2.6 V to about 2.7 V, about 2.6 V to about 2.8 V, about 2.6 V to about 2.9 V, about 2.6 V to about 3 V, about 2.7 V to about 2.8 V, about 2.7 V to about 2.9 V, about 2.7 V to about 3 V, about 2.8 V to about 2.9 V, about 2.8 V to about 3 V, or about 2.9 V to about 3 V. An electrochemical reduction system may have an operating voltage of about 2 V, about 2.1 V, about 2.2 V, about 2.3 V, about 2.4 V, about 2.5 V, about 2.6 V, about 2.7 V, about 2.8 V, about 2.9 V, or about 3 V. An electrochemical reduction system may have an operating voltage of at least about 2 V, about 2.1 V, about 2.2 V, about 2.3 V, about 2.4 V, about 2.5 V, about 2.6 V, about 2.7 V, about 2.8 V, or about 2.9 V. An electrochemical reduction system may have an operating voltage of at most about 2.1 V, about 2.2 V, about 2.3 V, about 2.4 V, about 2.5 V, about 2.6 V, about 2.7 V, about 2.8 V, about 2.9 V, or about 3 V. In some cases, the voltage may be increased or decreased by 0.05 V to achieve control over the fuel composition.

[0050] An electrochemical reduction system may have an operating voltage of about 3 volts (V) to about 4 V. An electrochemical reduction system may have an operating voltage of about 3 V to about 3.1 V, about 3 V to about 3.3 V, about 3 V to about 3.3 V, about 3 V to about 3.4 V, about 3 V to about 3.5 V, about 3 V to about 3.6 V, about 3 V to about 3.7 V, about 3 V to about 3.8 V, about 3 V to about 3.9 V, about 3 V to about 3 V, about 3.1 V to about 3.2 V, about 3.1 V to about 3.3 V, about 3.1 V to about 3.4 V, about 3.1 V to about 3.5 V, about 3.1 V to about 3.6 V, about 3.1 V to about 3.7 V, about 3.1 V to about 3.8 V, about 3.1 V to about 3.9 V, about 3.1 V to about 3 V, about 3.2 V to about 3.3 V, about 3.2 V toWSGR Docket No.56520-706.601 about 3.4 V, about 3.2 V to about 3.5 V, about 3.2 V to about 3.6 V, about 3.2 V to about 3.7 V, about 3.2 V to about 3.8 V, about 3.2 V to about 3.9 V, about 3.2 V to about 4 V, about 3.4 V to about 3.4 V, about 3.4 V to about 3.5 V, about 3.4 V to about 3.6 V, about 3.4 V to about 3.7 V, about 3.4 V to about 3.8 V, about 3.4 V to about 3.9 V, about 3.4 V to about 4 V, about 3.4 V to about 3.5 V, about 3.4 V to about 3.6 V, about 3.4 V to about 3.7 V, about 3.4 V to about 3.8 V, about 3.4 V to about 3.9 V, about 3.4 V to about 4 V, about 3.5 V to about 3.6 V, about 3.5 V to about 3.7 V, about 3.5 V to about 3.8 V, about 3.5 V to about 3.9 V, about 3.5 V to about 4 V, about 3.6 V to about 3.7 V, about 3.6 V to about 3.8 V, about 3.6 V to about 3.9 V, about 3.6 V to about 4 V, about 3.7 V to about 3.8 V, about 3.7 V to about 3.9 V, about 3.7 V to about 4 V, about 3.8 V to about 3.9 V, about 3.8 V to about 4 V, or about 3.9 V to about 4 V. An electrochemical reduction system may have an operating voltage of about 2 V, about 3.1 V, about 3.2 V, about 3.4 V, about 3.4 V, about 3.5 V, about 3.6 V, about 3.7 V, about 3.8 V, about 3.9 V, or about 4 V. An electrochemical reduction system may have an operating voltage of at least about 3 V, about 3.1 V, about 3.2 V, about 3.3 V, about 3.4 V, about 3.5 V, about 3.6 V, about 3.7 V, about 3.8 V, or about 3.9 V. An electrochemical reduction system may have an operating voltage of at most about 3.1 V, about 3.2 V, about 3.3 V, about 3.4 V, about 3.5 V, about 3.6 V, about 3.7 V, about 3.8 V, about 3.9 V, or about 4 V. In some cases, the voltage may be increased or decreased by 0.05 V to achieve control over the fuel composition.

[0051] An electrochemical reduction system may have an operating voltage of about 4 volts (V) to about 5 V. An electrochemical reduction system may have an operating voltage of about 4 V to about 4.1 V, about 4 V to about 4.4 V, about 4 V to about 4.5 V, about 4 V to about 4.4 V, about 4 V to about 4.5 V, about 4 V to about 4.6 V, about 4 V to about 4.7 V, about 4 V to about 4.8 V, about 4 V to about 4.9 V, about 4 V to about 5 V, about 4.1 V to about 4.4 V, about 4.1 V to about 4.5 V, about 4.1 V to about 4.4 V, about 4.1 V to about 4.5 V, about 4.1 V to about 4.6 V, about 4.1 V to about 4.7 V, about 4.1 V to about 4.8 V, about 4.1 V to about 4.9 V, about 4.1 V to about 5 V, about 4.4 V to about 4.5 V, about 4.4 V to about 4.4 V, about 4.4 V to about 4.5 V, about 4.4 V to about 4.6 V, about 4.4 V to about 4.7 V, about 4.4 V to about 4.8 V, about 4.4 V to about 4.9 V, about 4.4 V to about 5 V, about 4.5 V to about 4.4 V, about 4.5 V to about 4.5 V, about 4.5 V to about 4.6 V, about 4.5 V to about 4.7 V, about 4.5 V to about 4.8 V, about 4.5 V to about 4.9 V, about 4.5 V to about 5 V, about 4.4 V to about 4.5 V, about 4.4 V to about 4.6 V, about 4.4 V to about 4.7 V, about 4.4 V to about 4.8 V, about 4.4 V to about 4.9 V, about 4.4 V to about 5 V, about 4.5 V toWSGR Docket No.56520-706.601 about 4.6 V, about 4.5 V to about 4.7 V, about 4.5 V to about 4.8 V, about 4.5 V to about 4.9 V, about 4.5 V to about 5 V, about 4.6 V to about 4.7 V, about 4.6 V to about 4.8 V, about 4.6 V to about 4.9 V, about 4.6 V to about 5 V, about 4.7 V to about 4.8 V, about 4.7 V to about 4.9 V, about 4.7 V to about 5 V, about 4.8 V to about 4.9 V, about 4.8 V to about 5 V, or about 4.9 V to about 5 V. An electrochemical reduction system may have an operating voltage of about 4 V, about 4.1 V, about 4.4 V, about 4.5 V, about 4.4 V, about 4.5 V, about 4.6 V, about 4.7 V, about 4.8 V, about 4.9 V, or about 5 V. An electrochemical reduction system may have an operating voltage of at least about 4 V, about 4.1 V, about 4.4 V, about 4.5 V, about 4.4 V, about 4.5 V, about 4.6 V, about 4.7 V, about 4.8 V, or about 4.9 V. An electrochemical reduction system may have an operating voltage of at most about 4.1 V, about 4.4 V, about 4.5 V, about 4.4 V, about 4.5 V, about 4.6 V, about 4.7 V, about 4.8 V, about 4.9 V, or about 5 V. In some cases, the voltage may be increased or decreased by 0.05 V to achieve control over the fuel composition.

[0052] An electrochemical reduction system may have an operating voltage of about 5 volts (V) to about 6 V. An electrochemical reduction system may have an operating voltage of about 5 V to about 5.1 V, about 5 V to about 5.5 V, about 5 V to about 5.6 V, about 5 V to about 5.4 V, about 5 V to about 5.5 V, about 5 V to about 5.6 V, about 5 V to about 5.7 V, about 5 V to about 5.8 V, about 5 V to about 5.9 V, about 5 V to about 6 V, about 5.1 V to about 5.5 V, about 5.1 V to about 5.6 V, about 5.1 V to about 5.4 V, about 5.1 V to about 5.5 V, about 5.1 V to about 5.6 V, about 5.1 V to about 5.7 V, about 5.1 V to about 5.8 V, about 5.1 V to about 5.9 V, about 5.1 V to about 6 V, about 5.5 V to about 5.6 V, about 5.5 V to about 5.4 V, about 5.5 V to about 5.5 V, about 5.5 V to about 5.6 V, about 5.5 V to about 5.7 V, about 5.5 V to about 5.8 V, about 5.5 V to about 5.9 V, about 5.5 V to about 6 V, about 5.6 V to about 5.4 V, about 5.6 V to about 5.5 V, about 5.6 V to about 5.6 V, about 5.6 V to about 5.7 V, about 5.6 V to about 5.8 V, about 5.6 V to about 5.9 V, about 5.6 V to about 6 V, about 5.4 V to about 5.5 V, about 5.4 V to about 5.6 V, about 5.4 V to about 5.7 V, about 5.4 V to about 5.8 V, about 5.4 V to about 5.9 V, about 5.4 V to about 6 V, about 5.5 V to about 5.6 V, about 5.5 V to about 5.7 V, about 5.5 V to about 5.8 V, about 5.5 V to about 5.9 V, about 5.5 V to about 6 V, about 5.6 V to about 5.7 V, about 5.6 V to about 5.8 V, about 5.6 V to about 5.9 V, about 5.6 V to about 6 V, about 5.7 V to about 5.8 V, about 5.7 V to about 5.9 V, about 5.7 V to about 6 V, about 5.8 V to about 5.9 V, about 5.8 V to about 6 V, or about 5.9 V to about 6 V. An electrochemical reduction system may have an operating voltage of about 5 V, about 5.1 V, about 5.5 V, about 5.6 V, about 5.4 V, about 5.5 V, aboutWSGR Docket No.56520-706.601 5.6 V, about 5.7 V, about 5.8 V, about 5.9 V, or about 6 V. An electrochemical reduction system may have an operating voltage of at least about 5 V, about 5.1 V, about 5.5 V, about 5.6 V, about 5.4 V, about 5.5 V, about 5.6 V, about 5.7 V, about 5.8 V, or about 5.9 V. An electrochemical reduction system may have an operating voltage of at most about 5.1 V, about 5.5 V, about 5.6 V, about 5.4 V, about 5.5 V, about 5.6 V, about 5.7 V, about 5.8 V, about 5.9 V, or about 6 V. In some cases, the voltage may be increased or decreased by 0.05 V to achieve control over the fuel composition.

[0053] An anode may comprise an elemental metal such as nickel, iron, or iridium. 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 ion exchange membrane material or another physical separator that prevents contact with the cathode.

[0054] A cathode may comprise any appropriate material. In some embodiments, a cathode may comprise a catalyst. In some embodiments the cathode comprises a membrane comprising the catalyst. In some embodiments, the catalyst is used to reduce the carbon- containing material in the electrolyte. In some instances, a cathode may comprise copper nanoparticles and / or N-doped carbon nanomaterials. In some instances, a cathode may comprise alloys of two or more metals. 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 CO2or other chemical reactions. A cathode material may be in operative contact with an ion 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, the distance between the cathode and separator and / or the distance between the anode and separator may be adjusted (e.g., shortened or lengthened) to control reactions and products. In some instances, forced convective flow of electrolyte between the electrodes may further reduce electrical resistance and / or may involve greater distance between the electrodes. In some instances, the electrodes may be in different housings. 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. In some instances, a porous separator may be used.

[0055] An electrochemical reduction system may comprise one or more extractor units. An extractor unit may comprise any unit operation or separation unit that selectively separates one or more chemical species from a feed stream. In some instances, an extractorWSGR Docket No.56520-706.601 may comprise a membrane separator. In some instances, an extractor may comprise a micro- or nanostructured membrane. In some instances, an extractor may extract one or more chemical species derived from the reduction of carbon dioxide. In some instances, an extractor may extract one or more chemical species derived from the reduction of CO,CO2, carbonate ion, bicarbonate ions, or a reduced carbon species from an electrolyte solution. In other instances, an extractor may separate one or more chemical species derived from the subsequent reaction of carbon dioxide electrochemical reduction products.

[0056] 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 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. 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 electrical conductivity. 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 pore size of about 2 nm or less. In some instances, mesopores may be characterized as having an average pore size of between about 2 nm and about 20 nm. In some instances, micropores may be characterized as having an average pore size 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). Pores may have circular, oval, non- circular or irregular pore shapes or pore cross-section profiles. A pore size may be characterized as an average characteristic cross-sectional dimension (e.g., pore diameter or cross-sectional area). A membrane may comprise pores (e.g., micropores or nanopores) with an average cross-sectional dimension of at least about 0.5 nm, 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 100 nm, 250 nm, 500 nm, 1 micron (µm), or at least about 5 µm or more. A membrane may comprise pores with an average cross-sectional dimension of noWSGR Docket No.56520-706.601 more than about 5 µm, 1 µm, 500 nm, 250 nm, 100 nm, 50 nm, 40 nm, 30 nm, 20 nm, 15 nm, 10 nm, 5 nm, 1 nm, 0.5 nm or less.

[0057] 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 CO or CO2from 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.

[0058] An electrochemical reduction system may comprise one or more contactor units. A contactor unit 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. Such contactors may share design features with cooling towers. 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 carbon dioxide from a feed stream. In some instances, a contactor may separate CO or CO2from a feed stream and dissolve the CO or CO2in 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 CO2in a gas contactor may beWSGR Docket No.56520-706.601 enhanced by the presence of hydroxide ions generated within the electrochemical reduction system.

[0059] In some embodiments, the electrochemical reduction system comprises a voltage source configured to supply voltage to the electrochemical reduction system. In some embodiments, a carbon containing material (e.g., bicarbonate or carbonate) is reduced to a C1+ product in the electrochemical reduction system while a voltage is applied

[0060] Described herein are various chemical products and reaction mixtures generated via the electrochemical reduction of CO2captured from an input air stream. Electrochemical reduction comprises the addition of electrical energy (e.g., voltage) 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. In some embodiments, electrochemical reduction may produce carbon species comprising a chain length of 1 to 40 carbons. The products of the described electrochemical reduction systems may be further processed into useful products, including transportation fuels and polymers.

[0061] Described herein are various chemical products and reaction mixtures generated via the electrochemical reduction of CO2derived from a gas source. In some embodiments, a gaseous stream comprising CO2that contacts an electrolyte solution as described elsewhere herein comprises CO2from the atmosphere. In some embodiments, the gas source is the atmosphere. In some embodiments, a gaseous stream comprising CO2that contacts an electrolyte solution as described elsewhere herein comprises CO2from an industrial process. The gas source may be any CO2-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 systems and methods described herein may include organic molecules where one or more of the constituent carbon atoms are derived from CO2.

[0062] 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 CO2and carbon atoms derived from other sources (e.g. biogenic sources such as waste digesters or fermentation processes). In some instances, chemical products ofWSGR Docket No.56520-706.601 the systems and methods described herein may have a distinct carbon isotope signature that is consistent with the carbon isotope signature of CO2derived from the atmosphere. In some instances, chemical products and reaction mixtures of the systems and methods described herein may have a distinct carbon isotope signature that is not consistent with the carbon isotope signature of CO2derived from a non-atmospheric source such as the combustion of fossil fuels or the conversion of biological material into biofuels, allowing for identification of atmospheric CO2 fuels without requiring a chain of custody of production.

[0063] In some embodiments, provided herein is a method of a source of a fuel composition comprising measuring a carbon isotope of the fuel composition. In some embodiments, the methods verifies a fuel composition is produced from a particular source, such as atmospheric carbon dioxide. In some embodiments, the carbon isotope signature indicates whether a source comprises atmospheric carbon dioxide. In some embodiments, the carbon isotope signature indicates whether a source comprises a fossil fuel or a biofuel, as described elsewhere herein. In some embodiments, the carbon isotope signature indicates whether a fuel composition comprises a carbon neutral fuel.

[0064] In some embodiments, measuring a carbon isotope signature occurs onboard a vehicle configured to operate on a fuel composition. In some embodiments, measuring a carbon isotope signature occurs at a pump configured to dispense a fuel composition. In some embodiments, measuring a carbon isotope signature occurs on any system configured to operate on or dispense a fuel composition.

[0065] In some embodiments, the carbon isotope signature comprises a ratio of12C isotope to13C isotope, a concentration of13C isotope, a concentration (e.g., level) of14C isotope, or a combination thereof. In some embodiments, the carbon isotope signature comprises a ratio of12C isotope to13C isotope. In some embodiments, the carbon isotope signature comprises a concentration of13C isotope. In some embodiments, the carbon isotope signature comprises a concentration (e.g., level) of14C isotope The carbon isotope signature of a chemical product or reaction mixture may be measured by an isotopic ratio of14C:12C or13C:12C (e.g., expressed as a per mille difference). 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 for14C, Δ14C, may be calculated as:WSGR Docket No.56520-706.601

[0066] A per mille difference between the natural isotopic ratio of carbon and the measured isotopic ratio for13C, Δ13C, may be calculated as:A chemical product, reaction mixture, fuel composition may have a Δ14C of about -30 parts per thousand (‰), -25‰, -20‰, -15‰, -10‰, -5‰, 0‰, 5‰, 10‰, 20‰, or 30‰. A chemical product, reaction mixture, fuel composition may have a Δ14C of about -30 parts per thousand (‰), about -25‰, about -20‰, about -15‰, about -10‰, about -5‰, or about 0‰. A chemical product, reaction mixture, or fuel composition may have a Δ14C of at least about - 30‰, -25‰, -20‰, -15‰, -10‰, -5‰, 0‰, 5‰, 10‰, 20‰, 30‰, or more. A chemical product, reaction mixture, or fuel composition may have a Δ14C of at least about -30‰, about -25‰, about -20‰, about -15‰, about -10‰, about -5‰, about 0‰, or more. A chemical product, reaction mixture, or fuel composition may have a Δ14C of at most about -30‰, - 25‰, -20‰, -15‰, -10‰, -5‰, 0‰, 5‰, 10‰, 20‰, 30‰, or less. A chemical product, reaction mixture, or fuel composition may have a Δ14C of at most about -30‰, about -25‰, about -20‰, about -15‰, about -10‰, about -5‰, about 0‰, or less. A chemical product, reaction mixture, or fuel composition may have a Δ13C of about -30‰, about -28‰, about -26‰, about -25‰, about -24‰, about -22‰, about -20‰, about -15‰, about -10‰, about -8‰, or about -5‰. A chemical product, reaction mixture, or fuel composition may have a Δ13C of at least about -30‰, about -28‰, about -26‰, about -25‰, about -24‰, about -22‰, about -20‰, about -15‰, about -10‰, about -8‰, about -5‰ or more. A chemical product, reaction mixture, or fuel composition may have a Δ13C of at most about -30‰, about -28‰, about -26‰, about -25‰, about -24‰, about -22‰, about -20‰, about -15‰, about -10‰, about -8‰, about -5‰, or less. Provided herein are products or reaction mixtures comprising a composition that has a Δ13C of greater than -25‰ (e.g., from about -25‰ to about -8‰). In some embodiments, a chemical product, reaction mixture, orWSGR Docket No.56520-706.601 fuel composition may have a Δ13C of about -25‰ to about -1‰. In some embodiments, a chemical product, reaction mixture, or fuel composition may have a Δ13C of about -15‰ to about -1‰. In some embodiments, a chemical product, reaction mixture, or fuel composition may have a Δ13C of about -10‰ to about -5‰. In one example, the Δ13C may correspond to that of the ambient concentrations of the air from which CO2is captured (e.g., -8‰). Such Δ13C 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,13C levels are less than that of the atmosphere, and Δ13C may be -25‰. In another example, in fossil fuel (e.g., from oil, coal, etc.), the Δ13C may be even less than plant-based fuel, i.e., less than - 25‰. In some embodiments, a fossil fuel does not contain14C. In some embodiments, a fuel generated from atmosphere comprises a detectible level (e.g., concentration) of C14 isotopes. 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 (e.g., concentration) 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.

[0067] A chemical product or reaction mixture may include gaseous, liquid, or solid substances. Chemical products and reaction mixtures 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,WSGR Docket No.56520-706.601 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.

[0068] An organic compound (e.g., C1+ product) 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.

[0069] In some embodiments, a C1+ product may comprise about 1 carbon atom to about 40 carbon atoms. In some embodiments, a C1+ product may comprise about 1 carbon atom to about 30 carbon atoms. In some embodiments, a C1+ product may comprise about 1 carbon atom to about 20 carbon atoms. In some embodiments, a C1+ product may comprise about 10 carbon atom to about 20 carbon atoms. In some embodiments, a C1+ product may comprise about 12 carbon atom to about 20 carbon atoms.

[0070] 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,WSGR Docket No.56520-706.601 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.

[0071] 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.

[0072] 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 60WSGR Docket No.56520-706.601 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 C1 to about C2, about C1 to about C3, about C1 to about C4, about C1 to about C5, about C1 to about C6, about C1 to about C8, about C1 to about C10, about C1 to about C20, about C1 to about C30, about C1 to about C40, about C2 to about C3, about C2 to about C4, about C2 to about C5, about C2 to about C6, about C2 to about C8, about C2 to about C10, about C2 to about C20, about C2 to about C30, about C2 to about C40, about C3 to about C4, about C3 to about C5, about C3 to about C6, about C3 to about C8, about C3 to about C10, about C3 to about C20, about C3 to about C30, about C3 to about C40, about C4 to about C5, about C4 to about C6, about C4 to about C8, about C4 to about C10, about C4 to about C20, about C4 to about C30, about C4 to about C40, about C5 to about C6, about C5 to about C8, about C5 to about C10, about C5 to about C20, about C5 to about C30, about C5 to about C40, about C6 to about C8, about C6 to about C10, about C6 to about C20, about C6 to about C30, about C6 to about C40, about C8 to about C10, about C8 to about C20, about C8 to about C30, about C8 to about C40, about C10 to about C20, about C10 to about C30, about C10 to about C40, about C20 to about C30, about C20 to about C40, or about C30 to about C40.

[0073] 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,WSGR Docket No.56520-706.601 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.

[0074] 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 described herein 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-1152 / 97 standard for methanol purity.

[0075] 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.

[0076] An electrochemical reduction system may capture CO2and convert the CO2into 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 CO2may interact with an electrolyte solution. In some embodiments, the electrolyte solution comprises water. In some embodiments, the interaction of the input air stream comprising CO2and electrolyte solution takes place in a contactor. In some cases, interaction of the input air stream comprising CO2WSGR Docket No.56520-706.601 with the electrolyte solution may result in the capture of the CO2in the electrolyte. In some examples, the capture of CO2may occur as adsorption of the CO2onto the electrolyte or absorption of the CO2into the electrolyte. In some examples, the capture of CO2may occur as a physical interaction between CO2and the electrolyte (e.g., electrostatic interaction, adsorption, absorption). In some examples, capture of CO2may occur as a chemical interaction between CO2and the electrolyte, such as with an acid base reaction (e.g., . reaction with hydroxide ions or carbonate ions in the electrolyte). In some embodiments, captured CO2comprises a bicarbonate ion or a carbonate ion. In some embodiments, captured CO2comprises a bicarbonate ion and / or a carbonate ion. In some embodiments, the electrolyte solution comprises water. For example, an air stream comprising CO2may interact with water to yield carbonic acid which may further dissociate in water to a bicarbonate ion and a hydronium ion (e.g., H+, H3O+, or proton), as shown in the following reaction scheme:

[0077] 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, CO2may be transported to a separate chamber or compartment while captured in electrolyte solution. In some embodiments, the CO2is reduced in this separate chamber. In some examples, a captured CO2molecule (e.g., bicarbonate ion or carbonate ion) may be directly reduced in the presence of voltage to yield a reduced carbon product. In some instances, a captured CO2may not require release (e.g., desorption) from the captured CO2material prior to reduction into a reduced carbon product. For example, a captured CO2may be a bicarbonate ion or carbonate ion, and the bicarbonate or carbonate ion may directly be reduced to a reduced carbon product without an additional step requiring desorption of CO2from the bicarbonate or carbonate ion. In an example, captured CO2in the form of bicarbonate may be reduced to ethanol in the presence of a voltage according to the following reaction scheme:

[0078] A reduced carbon product may comprise an alcohol, aldehyde, alkene, alkane, acid, ketone, 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,WSGR Docket No.56520-706.601 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, 8 carbons, 9 carbons, 10 carbons, 11 carbons, 12 carbons, 13 carbons, 14 carbons, 15 carbons, 16 carbons, 17 carbons, 18 carbons, 19 carbons, 20 carbons, 30 carbons, 40 carbons, or more in length.

[0079] A reduced carbon product may comprise a hydrocarbon. A hydrocarbon may comprise an alkane, an alkene, an alkyne, an aromatic compound having only carbon and hydrogen atoms, or a combination thereof. In some embodiments, a hydrocarbon comprises an alkane with one or more carbon atoms (e.g., C1 to C40). In some embodiments, a hydrocarbon comprises an alkene with one or more carbon atoms (e.g., C1 to C40). In some embodiments, a hydrocarbon comprises an alkyne with one or more carbon atoms (e.g., C1 to C40). In some embodiments, a hydrocarbon comprises an aromatic compound with one or more carbon atoms (e.g., C1 to C40). In some embodiments, a hydrocarbon comprises at least 1 carbon, 2 carbons, 3 carbons, 4 carbons, 5 carbons, 6 carbons, 7 carbons, 8 carbons, 9 carbons, 10 carbons, 11 carbons, 12 carbons, 13 carbons, 14 carbons, 15 carbons, 16 carbons, 17 carbons, 18 carbons, 19 carbons, 20 carbons, 30 carbons, 40 carbons, or more.

[0080] In some embodiments, a fuel composition comprises a mixture of hydrocarbons. In some embodiments, a fuel composition comprises a mixture of hydrocarbons, each hydrocarbon having at least 1 carbon, 2 carbons, 3 carbons, 4 carbons, 5 carbons, 6 carbons, 7 carbons, 8 carbons, 9 carbons, 10 carbons, 11 carbons, 12 carbons, 13 carbons, 14 carbons, 15 carbons, 16 carbons, 17 carbons, 18 carbons, 19 carbons, 20 carbons, 30 carbons, 40 carbons, or more.

[0081] In some embodiments, a fuel composition comprises a mixture of hydrocarbons having a range of carbon atoms from about 1 carbon atom to about 40 carbon atoms. In some embodiments, the range of carbon atoms within the hydrocarbons of a fuel composition is selected depending upon the purpose of the fuel composition. For example, a fuel composition comprising about C4 to about C12 hydrocarbons can be used as gasoline. For example, a fuel composition comprising about C8 to about C17 hydrocarbons can be used as jet fuel. For example, a fuel composition comprising about C8 to about C20 hydrocarbons can be used as diesel fuel. For example, a fuel composition comprising about C20 to about C30 hydrocarbons can be used as lubricants. For example, a fuel composition comprising about C20 to about C50 hydrocarbons, or more, can be used as wax.

[0082] In some embodiments, a fuel composition is produced upon a request. In some embodiments, a request is provided by an individual or a computer. In some embodiments, aWSGR Docket No.56520-706.601 request comprises one or more details of a fuel composition comprising purpose (e.g., intended use or application), range of carbon atoms in mixture of hydrocarbons, mean number of carbon atoms in mixture of hydrocarbons, or an amount (mass or volume) of the fuel composition. For example, an individual may request a fuel composition suitable for jet fuel, and one or more parameters of the systems and methods described herein can be selected or adjusted to produce a fuel composition suitable for the request (jet fuel). In another example, an individual may request a fuel composition with a mean number of carbon atoms (of the hydrocarbons) of 12 (e.g., C12), and one or more parameters of the systems and methods described herein can be selected or adjusted to produce a fuel composition with a mean carbon number of 12. In another example, an individual may request a fuel composition with hydrocarbons ranging from about C2 to about C10, and one or more parameters of the systems and methods described herein can be selected or adjusted to produce a fuel composition with hydrocarbons ranging from about C2 to about C10.

[0083] The systems and methods described herein may produce a fuel composition comprising a mixture of hydrocarbons, where at least a given amount of the hydrocarbons in the mixture comprise a number of carbon atoms within a range of carbon atoms of a mean number of carbon atoms in the fuel composition. In some embodiments, the fuel composition is obtained in the absence of distillation. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. For example, a fuel composition having a mixture of hydrocarbons where the mean number of carbon atoms hydrocarbons is 7 may consist of at least 50% of the hydrocarbons in the mixture having a number of carbon atoms between 2 and 12.

[0084] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 10 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 8 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a meanWSGR Docket No.56520-706.601 number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 4 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 1 carbon atom of a mean number of carbon atoms in the mixture of hydrocarbons.

[0085] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 10 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 8 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 4 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture ofWSGR Docket No.56520-706.601 hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 1 carbon atom of a mean number of carbon atoms in the mixture of hydrocarbons.

[0086] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 10 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 8 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 4 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 1 carbon atom of a mean number of carbon atoms in the mixture of hydrocarbons.

[0087] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 10 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 8 carbon atoms of a mean number ofWSGR Docket No.56520-706.601 carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 4 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 1 carbon atom of a mean number of carbon atoms in the mixture of hydrocarbons.

[0088] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 10 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 8 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 4 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. InWSGR Docket No.56520-706.601 some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 1 carbon atom of a mean number of carbon atoms in the mixture of hydrocarbons.

[0089] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 10 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 8 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 4 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 95% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 1 carbon atom of a mean number of carbon atoms in the mixture of hydrocarbons.

[0090] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 20% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atomsWSGR Docket No.56520-706.601 in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 30% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 40% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 3 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons.

[0091] In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 20% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 30% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 40% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuelWSGR Docket No.56520-706.601 composition comprising a mixture of hydrocarbons will comprise at least 50% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 60% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 70% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 80% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons. In some embodiments, the fuel composition comprising a mixture of hydrocarbons will comprise at least 90% of hydrocarbons in the mixture of hydrocarbons having a number of carbon atoms within 2 carbon atoms of a mean number of carbon atoms in the mixture of hydrocarbons.

[0092] In some embodiments, the mean number of carbon atoms in a fuel composition is from about 1 to about 40. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 1 to about 12. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 4 to about 12. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 5 to about 14. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 6 to about 16. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 8 to about 21. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 18 to about 34. In some embodiments, the mean number of carbon atoms in a fuel composition is from about 18 to about 40.

[0093] In some embodiments, a reduced carbon product (RCP) may further be reduced in the presence of a voltage and / or electrolyte to form additional reduced carbon products (e.g., an upgraded RCP). In some embodiments, a RCP comprising an amine, hydride, alkyne, alkene, or cyclic functional groups may be further converted to an upgraded RCP no longer comprising one or more of the original functional groups.

[0094] In some embodiments, an upgraded RCP is a reduced carbon product comprising at least one additional carbon, hydrogen, or oxygen atom relative to the parentWSGR Docket No.56520-706.601 RCP. In some embodiments, an upgraded RCP may be referred to as an enlarged RCP herein. In some embodiments, the term “upgrading” may be referred to as “enlarging” herein.

[0095] In some embodiments, the electrochemical system is configured to produce alkanes, alkenes, or a combination thereof. In some embodiments, the electrochemical system produces alkanes, alkenes, alcohols (e.g., compounds comprising one or more hydroxyl groups), ketones, aldehydes, or a combination thereof. In some instances, aldehydes, ketones, and alcohols may undergo secondary reactions (e.g., further reactions) to yield upgraded RCPs.

[0096] In some embodiments, the conversion of CO2to ethanol and hydroxide ions is according to the following chemical reaction, where CO2and HCO3- are in equilibrium within the solution:

[0097] 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 CO2solution may convert at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, 99%, or 100% of the captured CO2into a reduced carbon product.

[0098] 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. In some embodiments, a separation unit includes gas adsorption columns. In some embodiments, separation unit includes adsorption systems. In some embodiments, separation units include membranes. In some embodiments, separation is achieved in the absence of distillation. In some embodiments, the fuel compositions described herein are obtained in the absence of distillation.

[0099] 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 includeWSGR Docket No.56520-706.601 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 conversion reactions including dehydrogenation, hydrogenation, cracking, dehydration, decarboxylation, carboxylation, amination, deamination, alkylation, dealkylation, oxidation, reduction, polymerization, and depolymerization.

[0100] A chemical conversion system may comprise one or more electrochemical reduction units (e.g., stacks). In some embodiments, a chemical conversion system comprises one stack. In some embodiments, a chemical conversion system comprises two or more stacks. In some embodiments, stacks are used to generate a RCP and / or upgrade a RCP. For example, in a system comprising one stack, RCPs may be generated in the stack while a voltage is applied, and at least a portion of the RCPs may be recirculated back to the stack for upgrading (e.g., into larger RCPs). In another example, in a system comprising two stacks, RCPs may be generated in a first stack and at least a portion of the RCPs may be directed to a second stack for upgrading (e.g., into larger RCPs).

[0101] In the electrochemical reduction of CO2, various reduced carbon products (“RCPs”) may be generated, including but not limited to C1-C40 alcohols, C1-C40 aldehydes, C1-C40 ketones, C1-C40 linear alkanes, C1-C40 linear alkenes, C1-C40 branched alkanes, C1-C40 branched alkenes, C1-C40 cyclic alkanes, and C1-40 cyclic alkenes, or a combination thereof. In some cases, allowing these reduced carbon products to be retained within the electrochemical reactor may allow for their enlargement, such that further carbon, hydrogen, and in some cases oxygen atoms are added to them, along with electrons, increasing their size and energy and changing their combustion characteristics. For example, ethanol may be produced as an initial RCP of a CO2reduction reaction. By remaining in the electrochemical stack for a longer period of time (e.g., in a taller stack, in a wider stack, a lower flow rate, with longer residence time), the ethanol may act as a reactant for further reduction reactions (such as ethanol to butanol), thereby producing a larger RCP.

[0102] In some embodiments, an upgraded RCP is a carbon product that comprises at least one additional carbon atom, hydrogen atom, or oxygen atom, or combination thereof from the corresponding, original RCP (e.g., parent RCP). In some embodiments, an upgradedWSGR Docket No.56520-706.601 RCP may be referred to as an enlarged RCP herein. In some embodiments, an upgraded RCP comprises at least one additional carbon atom from the corresponding original RCP. For example, an upgraded RCP may be dodecane, while the original RCP is butane. In some embodiments, an upgraded RCP comprises at least one additional oxygen atom from the corresponding original RCP. For example, an upgraded RCP may be a C12 ketone, while the original RCP is a C10 alkene.

[0103] In some instances, upgrading RCPs comprises introducing additional oxygen to the RCP (e.g., hydroxyl group). In some embodiments, an increased number of oxygen atoms in an RCP correlates to a greater solubility of the RCP in an aqueous phase.

[0104] In some embodiments, upgrading comprises oligomerization of two or more RCPs. For example, two C2RCPs may react during an electrochemical reduction process (e.g., upgrading process) to yield one C4RCP. In some embodiments, upgrading comprises reacting with additional electrolyte (e.g., bicarbonate). For example, a C3RCP may react with bicarbonate in an electrochemical stack during an upgrading process to yield a C4RCP. In some embodiments, two or more RCPs are generated that have chemical reactivity such that the two or more RCPs oligomerize without receiving electrons from a cathode. For example, two butanal molecules could undergo an aldol condensation reaction to form 2 ethyl hexanol, or similar reactions to form enlarged products.

[0105] In some cases, reduced carbon products may be separated from the electrolyte stream and introduced into a separate electrochemical reactor where they may undergo further reduction which may allow for their enlargement, such that further carbon, hydrogen, and in some cases oxygen atoms are added to them, along with electrons, increasing their size and energy and changing their combustion characteristics. For example, ethanol may be produced as an initial RCP of a CO2reduction reaction, be directed to a second, separate electrochemical reactor which may comprise an electrochemical stack, and be further reduced to butanol, thereby producing a larger RCP. For example, a mixture of C1-C15 RCPs may be produced in a first stack, where RCPs comprising 6 carbon atoms or more may be separated from the mixture through a micro- or nanostructured membrane (e.g., a membrane comprising carbon nanotubes), and RCPs comprising 5 carbon atoms or less may be directed to a second stack (or recirculated back to the first stack) for further reacting and upgrading.

[0106] In some embodiments, a RCP may comprise a molar heat of combustion at 298K and constant pressure of at least about -15,000 kilojoules per mol (kJ / mol), -14,000 kJ / mol, -13,000 kJ / mol, -12,000 kJ / mol, -11,000 kJ / mol, -10,000 kJ / mol, -9,000 kJ / mol, -WSGR Docket No.56520-706.601 8,000 kJ / mol, -7,000 kJ / mol, -6,000 kJ / mol, -5,000 kJ / mol, -4,000 kJ / mol, -3,000 kJ / mol, - 2,000 kJ / mol, -1000 kJ / mol, -900 kJ / mol, -800 kJ / mol, -700 kJ / mol, -600 kJ / mol, -500 kJ / mol, -400 kJ / mol, -300 kJ / mol, -200 kJ / mol, -100 kJ / mol or less.

[0107] In some embodiments, a mixture of RCPs (e.g., a fuel composition) may comprise a molar heat of combustion at 298K and constant pressure of at least about -15,000 kilojoules per mol (kJ / mol), -14,000 kJ / mol, -13,000 kJ / mol, -12,000 kJ / mol, -11,000 kJ / mol, -10,000 kJ / mol, -9,000 kJ / mol, -8,000 kJ / mol, -7,000 kJ / mol, -6,000 kJ / mol, -5,000 kJ / mol, - 4,000 kJ / mol, -3,000 kJ / mol, -2,000 kJ / mol, -1000 kJ / mol, -900 kJ / mol, -800 kJ / mol, -700 kJ / mol, -600 kJ / mol, -500 kJ / mol, -400 kJ / mol, -300 kJ / mol, -200 kJ / mol, -100 kJ / mol or less.

[0108] In some embodiments, an upgraded RCP may comprise a molar heat of combustion at 298K and constant pressure of at least about -15,000 kilojoules per mol (kJ / mol), -14,000 kJ / mol, -13,000 kJ / mol, -12,000 kJ / mol, -11,000 kJ / mol, -10,000 kJ / mol, - 9,000 kJ / mol, -8,000 kJ / mol, -7,000 kJ / mol, -6,000 kJ / mol, -5,000 kJ / mol, -4,000 kJ / mol, - 3,000 kJ / mol, -2,000 kJ / mol, -1000 kJ / mol, -900 kJ / mol, -800 kJ / mol, -700 kJ / mol, -600 kJ / mol, -500 kJ / mol, -400 kJ / mol, -300 kJ / mol, -200 kJ / mol, -100 kJ / mol or less.

[0109] In some embodiments, a RCP may comprise a molar heat of combustion that is more than (e.g., less negative than) the molar heat of combustion of an upgraded RCP. For example, if the molar heat of combustion is about -1,000 kJ / mol of a RCP, then the heat of combustion for a corresponding upgraded RCP will be less than -1,000 kJ / mol (e.g., <-1,000 kJ / mol).

[0110] The residence time of a RCP in an electrochemical reduction system may affect the size (e.g., molar weight) of the RCP. In some embodiments, the residence time of a RCP in a stack is determined as a factor of the dimension of the stack. In some embodiments, a taller (vertical height) electrochemical reduction stack results in longer residence times, compared to a relatively shorter stack. In some embodiments, a shorter (vertical height) electrochemical reduction stack results in shorter residence times, compared to a relatively taller stack. In some embodiments, a wider (horizontal) electrochemical reduction stack results in a longer residence time, compared to a relatively narrower stack. In some embodiments, a narrower (horizontal) electrochemical reduction stack results in a shorter residence time, compared to a relatively wider stack.

[0111] Depending on the objective of operating the electrochemical reduction system, it may be desirable to have a RCP reside within the electrochemical reduction system for shortWSGR Docket No.56520-706.601 or long periods of time. For example, a goal may be to separate the RCPs in a vapor phase, so a shorter residence time will suffice in order to yield smaller RCPs (e.g., less than 6 carbons) that may easily be vaporized. On the other hand, for example, a goal may be to yield RCPs with higher energy density (e.g., for increased compatibility with engines designed to run on diesel or jet fuel), so a longer residence time in the electrochemical reduction system is required to yield the longer carbon chain (e.g., higher molecular weight) RCPs. In some embodiments, a longer residence time may be completed in a single electrochemical reduction unit. In some embodiments, a longer residence time may be completed in two or more electrochemical reduction units. For example, a RCP may be produced in a first electrochemical reduction unit (e.g., stack) in a fixed amount of time and directed to a second electrochemical reduction unit for further reduction in an additional fixed amount of time. The second electrochemical reduction unit may be referred to as a second electrochemical stack, upgrading stack, oligomerization stack, or cyclization stack herein. The fixed amount of time may be the same or different.

[0112] There may be opposing objectives in operating a CO2electrochemical reduction system with respect to the size and residence time of RCPs. On one hand, it may be desirable to separate the reduced carbon products in the vapor phase, which operates best on smaller carbon products, for example on RCPs that have less than 6 carbon atoms. However, it can be desirable to produce longer carbon chain products (“enlarged” RCPs) due to their increased energy density and increased compatibility with engines designed to run on diesel or jet fuels, for example.

[0113] It may be particularly useful to remove, or separate out, RCPs continuously while operating an integrated direct air capture (DAC) and electrochemical stack system. Continuously separating and removing RCPs during operation may allow for a minimal number of RCPs to remain in the stream that is directed back to the DAC unit, a minimal number of RCPs that are vaporized and lost to the air during additional capture of CO2, and may allow for yielding larger (e.g., higher molecular weight) RCPs through additional electrochemical reduction. Disclosed herein are systems and methods for continuously removing (or separating) RCPs in order to minimize the number of RCPs lost to the air while also producing larger RCPs.

[0114] In some embodiments, one or more parameters of an electrochemical stack system may be selected or adjusted for selectively producing a fuel composition. In some embodiments, a composition of the electrolyte solution, a pH of the electrolyte solution, aWSGR Docket No.56520-706.601 concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition .

[0115] In some embodiments, a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0116] In some embodiments, at least two of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0117] In some embodiments, at least three of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.WSGR Docket No.56520-706.601

[0118] In some embodiments, at least four of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0119] In some embodiments, at least five of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0120] In some embodiments, at least six of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0121] In some embodiments, at least seven of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system,WSGR Docket No.56520-706.601 electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0122] In some embodiments, at least eight of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0123] In some embodiments, at least nine of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition..

[0124] In some embodiments, all of the following parameters are adjusted to yield an RCP of a desired size: a composition of the electrolyte solution, a pH of the electrolyte solution, a concentration of the total inorganic carbon (TIC) in the electrolyte solution, flow rate of electrolyte solution (with dissolved CO2), a residence time of the captured CO2in the electrochemical reduction system, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, electrochemical stack dimension, catalyst design (e.g., distance between active sites on the catalyst), a voltage applied to the electrochemical reduction system, or a combination thereof are adjusted to yield a fuel composition.

[0125] In some embodiments, an electrochemical reduction system described herein operates under a set of one or more parameters selected from the group consisting of: a composition of the electrolyte solution, a temperature of the electrochemical reductionWSGR Docket No.56520-706.601 system, a composition of a catalyst in the electrochemical reduction system, a distance between active sites on a catalyst in the electrochemical reduction system, a residence time of the captured CO2in the electrochemical reduction system, a voltage applied to the electrochemical reduction system, a pH of the electrolyte solution, and a concentration of total inorganic carbon (TIC) in the electrolyte solution.

[0126] In some embodiments, at least one parameter of an electrochemical reduction system is selected or adjusted to yield a fuel composition comprising a mean number of carbon atoms. For example, a request is received for a fuel composition having a mean number of carbon atoms of 12, so at least one parameter (described herein) of any electrochemical reduction system is selected or adjusted to yield a fuel composition comprising a mean number of carbon atoms of 12. In another example, a request is received for a fuel composition having a mean number of carbon atoms of 12, so the residence time of the captured CO2in the electrochemical reduction system is selected to yield a fuel composition comprising a mean number of carbon atoms of 12. In yet another example, a request is received for a fuel composition having a mean number of carbon atoms of 12, the pH of the electrolyte solution is adjusted to yield a fuel composition comprising a mean number of carbon atoms of 12.

[0127] In some embodiments, an electrochemical reduction system comprises an electrochemical stack as described elsewhere herein. In some embodiments, the electrochemical stack comprises a surface area. In some embodiments, the surface area of the electrochemical stack has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a larger surface area yields a higher mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical stack comprising a smaller surface area. In some embodiments, a smaller surface area yields a lower mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical stack comprising a larger surface area. In some cases, a short and wide stack yields a higher mean number of carbon atoms in the fuel composition than a tall and thin stack. In some embodiments, the dimensions of the stack are positively correlated with residence time of an electrolyte solution in the stack during reduction. In some cases, a stack with a larger surface area (e.g., short and wide) may allow for an increased residence time of the electrolyte solution than a stack with a smaller surface area.

[0128] In some embodiments, the one or more parameters comprises a residence time of the captured CO2in the electrochemical reduction system. In some embodiments, theWSGR Docket No.56520-706.601 residence time of the captured CO2in the electrochemical reduction system is selected or adjusted to yield a fuel composition comprising a specific mean number of carbon atoms. In some embodiments, the residence time of the captured CO2in the electrochemical reduction system has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively shorter residence time of the captured CO2in the electrochemical reduction system yields a smaller mean carbon atom number in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively longer residence time. In some embodiments, a relatively longer residence time of the captured CO2in the electrochemical reduction system yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively shorter residence time. For example, a residence time for an electrolyte solution of about 1 minute may yield a fuel composition having a mean number of carbon atoms of 2, depending on the other conditions, whereas a residence time of about 5 minutes may yield a fuel composition having a mean number of carbon atoms of 6, depending on other conditions.

[0129] In some embodiments, the one or more parameters comprises a temperature of the electrochemical reduction system. In some embodiments, the temperature of the electrochemical reduction system is selected or adjusted to yield a fuel composition having a specific mean number of carbon atoms. In some embodiments, the temperature of the electrochemical reduction system has a negative correlation to the mean number of carbon atoms yielded in the fuel composition. In some embodiments, a relatively higher temperature yields a smaller mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical reduction stack operating at a relatively lower temperature. In some embodiments, a relatively lower temperature yields a larger mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical reduction stack operating at a relatively higher temperature. For example, an electrochemical reduction system operating at 15°C may yield a fuel composition with a mean number of carbon atoms of 3, depending on other conditions, whereas the same electrochemical reduction system operating at 40°C may yield a fuel composition with a mean number of carbon atoms of 2, depending on other conditions.

[0130] In some embodiments, the one or more parameters comprises a voltage applied to the electrochemical reduction system. In some embodiments, the voltage is selected or adjusted to yield a fuel composition comprising a specific mean number of carbon atoms. InWSGR Docket No.56520-706.601 some embodiments, the voltage applied to the electrochemical reduction system has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher voltage yields a larger mean carbon atom numbers in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively lower voltage. In some embodiments, a relatively lower voltage yields a smaller mean carbon atom numbers in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively higher voltage. For example, a voltage of about 3 V applied to the electrochemical reduction system may yield a fuel composition having a mean number of carbon atoms of 2, depending on other conditions, whereas a voltage of about 4V applied to the electrochemical reduction system may yield a fuel composition having a mean number of carbon atoms of 4, depending on other conditions.

[0131] The pH of an electrochemical stack can be adjusted or selected to tune the identity or molecular weight of an RCP. The pH of a stack can be adjusted by adding acidic solution or basic solution to the stack. The pH of a stack can be adjusted by adding or subtracting electrolyte solution from a stack. In some embodiments, an electrochemical stack is operated at a pH of about 9 to about 14. In some embodiments, an electrochemical stack is operated at a pH of about 5, about 6, about 7, about 8, about 9, about10, about 11, about 12, about 13, or about 14. In some embodiments, an electrochemical stack is operated at a pH of at least 10. The specific pH may be selected to tune the identity or molecular weight of an RCP. For example, a stack operated at a higher pH may yield an RCP with a greater amount of carbons (e.g., fuel composition having a higher mean number of carbon atoms) as compared to a stack with a relatively lower pH. Operating the pH of a stack at an increased pH, either individually or in conjunction with adjusting at least one other parameter of the stack, may result in a fuel composition having a specific mean number of carbon atoms, depending on other conditions.

[0132] In some embodiments, the one or more parameters comprises a pH of the electrolyte solution. In some embodiments, the pH of the electrolyte solution is selected or adjusted to yield a fuel composition comprising a specific mean number of carbon atoms. In some embodiments, the pH of the electrolyte solution has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher pH of the electrolyte solution yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively lower pH. In some embodiments, a relatively lower pH of the electrolyte solution yields a smaller meanWSGR Docket No.56520-706.601 carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively higher pH. For example, an electrolyte solution comprising a pH of about 6 may yield a fuel composition having a mean number of carbon atoms of 1, depending on other conditions, whereas an electrolyte solution comprising a pH of about 12 may yield a fuel composition having a mean number of carbon atoms of 4, depending on other conditions.

[0133] In some embodiments, the total inorganic carbon within an electrochemical stack may be selected to tune the identity or molecular weight of an RCP. In some cases, the TIC in an electrochemical stack is about 0.5 mol / L (M) to about 2.5 M. In some cases, the TIC in an electrochemical stack is about 0.5 M to about 1 M, about 0.5 M to about 1.25 M, about 0.5 M to about 1.5 M, about 0.5 M to about 1.75 M, about 0.5 M to about 2 M, about 0.5 M to about 2.5 M, about 1 M to about 1.25 M, about 1 M to about 1.5 M, about 1 M to about 1.75 M, about 1 M to about 2 M, about 1 M to about 2.5 M, about 1.25 M to about 1.5 M, about 1.25 M to about 1.75 M, about 1.25 M to about 2 M, about 1.25 M to about 2.5 M, about 1.5 M to about 1.75 M, about 1.5 M to about 2 M, about 1.5 M to about 2.5 M, about 1.75 M to about 2 M, about 1.75 M to about 2.5 M, or about 2 M to about 2.5 M. In some cases, the TIC in an electrochemical stack is about 0.5 M, about 1 M, about 1.25 M, about 1.5 M, about 1.75 M, about 2 M, or about 2.5 M. The specific pH may be selected to tune the identity or molecular weight of an RCP. In some cases, a stack operated with a higher TIC may yield an RCP with a greater amount of carbons as compared to a stack with a relatively lower TIC. Operating the pH of a stack at an increased TIC concentration, either individually or in conjunction with adjusting at least one other parameter of the stack, may result in a fuel composition having a specific mean number of carbon atoms.

[0134] In some embodiments, the one or more parameters comprises a concentration of total inorganic carbon (TIC) in the electrolyte solution. In some embodiments, the concentration of the TIC in the electrolyte solution is selected or adjusted to yield a fuel composition comprising a specific mean number of carbon atoms. In some embodiments, the concentration of the TIC in the electrolyte solution has a positive correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a relatively higher concentration of TIC yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively lower concentration of TIC. In some embodiments, a relatively lower concentration of TIC yields a smaller mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively higher concentration of TIC. For example, a solution having a TIC ofWSGR Docket No.56520-706.601 about 0.1M may yield a fuel composition having a mean number of carbon atoms of 2, depending on other conditions, whereas a solution having a TIC of about 1.5 M may yield a fuel composition having a mean number of carbon atoms of 4, depending on other conditions.

[0135] In some embodiments, the flow rate or flow profile of the electrolyte solution or other fluids throughout an electrochemical stack is reduced to eliminate turbulent flow. In some cases, an electrolyte solution has a laminar flow profile within an electrochemical stack. In some cases, flow of the electrolyte solution throughout the electrochemical stack is characterized by a Reynolds' number of about 500 to about 3,000. In some cases, flow of the electrolyte solution throughout the electrochemical stack is characterized by a Reynolds' number of about 500 to about 1,000, about 500 to about 1,500, about 500 to about 2,000, about 500 to about 2,500, about 500 to about 3,000, about 1,000 to about 1,500, about 1,000 to about 2,000, about 1,000 to about 2,500, about 1,000 to about 3,000, about 1,500 to about 2,000, about 1,500 to about 2,500, about 1,500 to about 3,000, about 2,000 to about 2,500, about 2,000 to about 3,000, or about 2,500 to about 3,000. In some cases, flow of the electrolyte solution throughout the electrochemical stack is characterized by a Reynolds' number of about 500, about 1,000, about 1,500, about 2,000, about 2,500, or about 3,000. In some cases, flow of the electrolyte solution throughout the electrochemical stack is characterized by a Reynolds' number of at most about 1,000, about 1,500, about 2,000, about 2,500, or about 3,000. The flow rate or flow profile of the electrolyte solution or other fluids throughout the electrochemical stack may be selected to tune the identity or molecular weight of an RCP. In some cases, a stack operated with a lower flow rate or Reynolds’ number may yield an RCP with a greater amount of carbons as compared to a stack with a relatively lower flow rate or Reynolds’ number. In some instances, a laminar flow profile may increase the contact time of an RCP with a catalyst within the electrochemical stack, thus yielding an enlarged RCP. Operating the stack with a laminar flow profile, either individually or in conjunction with adjusting at least one other parameter of the stack, may result in an enlarged RCP (or an RCP with greater than 12 carbon atoms, for example).

[0136] In some embodiments, a catalyst is used within an electrochemical stack to facilitate reduction of CO2or yield fuel compositions having a specific mean number of carbon atoms. The identity or composition (of the catalyst) can be adjusted or selected to tune the identity or molecular weight of a hydrocarbon. For example, the size of a catalyst nanoparticle can be adjusted to decrease the number of carbon atoms in a hydrocarbon. In some cases, a catalyst comprises nanoparticles with a diameter of about 25 nm to about 100WSGR Docket No.56520-706.601 nm. In some cases, a catalyst comprises nanoparticles with a diameter of about 25 nm to about 50 nm, about 25 nm to about 75 nm, about 25 nm to about 100 nm, about 50 nm to about 75 nm, about 50 nm to about 100 nm, or about 75 nm to about 100 nm. In some cases, a catalyst comprises nanoparticles with a diameter of about 25 nm, about 50 nm, about 75 nm, or about 100 nm. In some cases, a catalyst comprises nanoparticles with a diameter of at least about 25 nm, about 50 nm, or about 75 nm. In some cases, a catalyst comprises nanoparticles with a diameter of at most about 50 nm, about 75 nm, or about 100 nm. In some cases, a stack comprising a catalyst with larger nanoparticles may yield an RCP with a greater amount of carbons as compared to a stack comprising a catalyst with relatively smaller nanoparticles. Adjusting catalyst size, either individually or in conjunction with adjusting at least one other parameter of the stack, may result in a fuel composition having a specific mean number of carbon atoms.

[0137] In some embodiments, a catalyst comprises copper, nickel, platinum, iridium, ruthenium, palladium, tin, silver, gold, or a combination thereof. In some embodiments, a catalyst comprises copper. In some embodiments, a catalyst comprises nickel. In some embodiments, a catalyst comprises platinum. In some embodiments, a catalyst comprises palladium. In some embodiments, a catalyst comprises silver. In some embodiments, a catalyst comprises gold.

[0138] In some embodiments, the one or more parameters comprises a distance between active sites on a catalyst in the electrochemical reduction system. In some embodiments, the distance between active sites on the catalyst in the electrochemical reduction system is selected or adjusted to yield a fuel composition comprising a specific mean number of carbon atoms. In some embodiments, the distance between active sites on the catalyst in the electrochemical reduction system has a negative correlation to the mean number of carbon atoms in the fuel composition. In some embodiments, a catalyst comprising a relatively shorter distance between active sites yields a larger mean carbon atom number in the fuel composition than an otherwise similar catalyst comprising a relatively longer distance between active sites. In some embodiments, a catalyst comprising a relatively longer distance between active sites yields a smaller mean carbon atom number in the fuel composition than an otherwise similar catalyst comprising a relatively shorter distance between active sites.

[0139] Various embodiments of a CO2reduction system capable of continuously removing RCPs while allowing for the production of larger sized carbon products are described herein. For example, referring to FIG.1, RCPs can be generated in anWSGR Docket No.56520-706.601 electrochemical stack and removed from the electrolyte. RCPs can leave the stack by heat, gas stripping, adsorption, or a combination thereof prior to sending the depleted electrolyte back to the DAC system for further capture of CO2. Removed RCPs may be present with some water (which was also removed from the electrolyte by the removal process) and can be directed to a second electrochemical stack for further reduction into larger RCPs. For example, the first electrochemical stack may mostly produce a mixture of C1to C4RCPs which may be further reduced to C5to C16RCPs in the second electrochemical stack.

[0140] In some instances, as depicted in FIG.1, an electrolyte stream 107, containing an electrolyte solution (e.g., water) for use in an electrochemical CO2reduction process, may be contacted with a CO2containing gas in a direct air capture (DAC) unit 108 to produce a CO2enriched electrolyte. In some cases, the CO2enriched electrolyte contains bicarbonate and / or carbonate, which form equilibria with one another depending on pH. The CO2containing gas may be air from the atmosphere and directed into the DAC unit 108 through an inlet (not shown). In some instances, the pH, temperature, or other property of the electrolyte stream 107 may be controlled such to optimize capture of CO2from the CO2containing gas into the electrolyte solution. In some instances, the CO2containing gas also contains water which may also be absorbed by the electrolyte stream.

[0141] The CO2-enriched electrolyte stream 101 may enter a first electrochemical stack 102. The electrochemical stack 102 may contain a cathode, an anode, and an ion-exchange membrane. Within the electrochemical stack, electrical energy (e.g., applied voltage) may cause the carbon in the electrolyte solution 101 to be reduced into one or more types of RCPs. The first electrochemical stack 102 may comprise a first catalyst. In some embodiments, the first catalyst comprises copper, defect-containing or doped carbon materials, silver palladium, or nickel, or any combination thereof. The RCPs produced in the first stack 102 may have less carbon atoms than RCPs produced in the second stack 106. Certain parameters of the first stack 102 can be tuned to produce RCPs of a smaller size as compared to the second electrochemical stack. Such parameters can include pH, total inorganic carbon, stack height, stack width, catalyst size, residence time, flow rate, or flow profile, or any combination thereof.

[0142] The RCP-enriched electrolyte stream 103 may be directed to an extraction or separation means 104. The extractor 104 may separate RCPs from the electrolyte solution. The RCPs may be removed from the electrolyte solution by heat stripping, gas stripping, or adsorption, or any combination thereof. The electrolyte solution, which may be depleted ofWSGR Docket No.56520-706.601 RCPs (e.g., depleted electrolyte), may exit the extractor 104 as electrolyte stream 107 back into the DAC unit 108 for additional capture of CO2, so it can be reused within the electrochemical reduction system as described herein. The electrolyte stream 107 may enter the DAC 108 where it can be used to capture additional CO2. It may be particularly useful to remove RCPs continuously, such that none or very little RCPS remain in the electrolyte stream 107 that is directed to the DAC 108. This may prevent RCPs being lost to the air during direct air capture of CO2. In some embodiments, the electrolyte stream exiting extractor 104 may not be reused within the electrochemical reduction system.

[0143] The reduced carbon products may exit the extractor 104 as RCP stream 105 and enter a second electrochemical stack 106. In some cases, the RCP stream 105 comprises RCPs that are present in water which may have been removed from the electrolyte solution in extractor 104. The second electrochemical stack 106 may be used to further reduce, or upgrade, RCPs into larger, reduced carbon products with higher molecular weights. The second electrochemical stack 106 may contain a second cathode, a second anode, and a second membrane. The second electrochemical stack 106 may comprise a second catalyst. In some embodiments, the second catalyst comprises copper, defect-containing or doped carbon materials, silver palladium, or nickel, or any combination thereof. In some cases, the second catalyst comprises the same materials as the first catalyst. In some cases, the second catalyst comprises the same materials as the first catalyst but in a different proportion or amount. In some embodiments, the second catalyst acts to produce an upgraded set of RCPs that are larger (e.g., higher molecular weight) and / or cyclic . The second catalyst may comprise catalyst materials designed specifically to produce desired carbon products, such as branched or cyclic carbon molecules. Certain parameters of the second stack 106 can be tuned to produce RCPs of a larger size as compared to the first electrochemical stack. Such parameters can include pH, total inorganic carbon, stack height, stack width, catalyst size, residence time, flow rate, or flow profile, or any combination thereof.

[0144] The electrochemical reduction of RCPs in the second electrochemical stack 106 may take place in the liquid phase, gas phase, or a mixed phase. In some cases, the reduction reaction in the second electrochemical stack 106 takes place in the gas phase, utilizing humidified air comprising RCPs. In some cases, the reduction reaction in the second electrochemical stack 106 may be in the aqueous phase, utilizing an electrolyte. Hydrogen may be introduced into the second electrochemical stack 106. In some cases, the introduced hydrogen is produced in the first electrochemical stack 102 and directed to the secondWSGR Docket No.56520-706.601 electrochemical stack 106. In some cases, the second electrochemical stack may be gas phase and may contain humidified air containing RCPs and / or hydrogen gas. The temperature of the second stack 106 may be higher or lower than the first stack 102, to facilitate the production of RCPs of a desired size.

[0145] The enlarged RCPs may exit the second electrochemical stack 106 as RCP stream 109 and enter a second separation unit 110. The second separation unit 110 may also be referred to as a split. Within the second separation unit 110, the enlarged RCPs may be separated based on their size. Larger RCPs (e.g., with a carbon number range from about C12, or more, for example) may be separated from smaller RCPs (e.g., with a carbon number range from about C1to about C12,for example) by a variety of means, including vapor or pervaporation (PV) separation methods utilizing carbon nanotube (“CNT”) membranes, hydrocyclones, or adsorption separation, for example. The larger RCPs may be sparingly soluble or insoluble in water, and may have low vapor pressures, necessitating different separation methods than those that may be ideally used in the separation of RCPs produced in the first electrochemical stack. After separation, smaller (e.g., lower molecular weight) RCPs may exit the split 110 as stream 112 and reenter the second electrochemical stack 106 to be further reduced. RCPs with an increased carbon number may exit the split 110 as stream 111 and be used or sold as a finished product or undergo further processing. In some cases, the stream 111 can be sold or used as a finished fuel product, including diesel or jet fuel.

[0146] In some instances, as depicted in FIG.2, an electrolyte stream 209, containing an electrolyte solution (e.g., water) for use in an electrochemical CO2reduction process, may be contacted with a CO2containing gas in a direct air capture (DAC) unit 210 to produce a CO2enriched electrolyte. In some cases, the CO2enriched electrolyte contains bicarbonate. The CO2containing gas may be air from the atmosphere and directed into the DAC units 210 through an inlet (not shown). In some instances, the temperature or other property of the electrolyte stream 209 may be controlled such to optimize capture of CO2from the CO2containing gas into the electrolyte solution. In some instances, the CO2containing gas also contains water which may also be absorbed by the electrolyte stream 209.

[0147] The CO2-enriched electrolyte stream 201 may enter an electrochemical stack 202. The electrochemical stack 202 may contain a cathode, an anode, and a membrane, and within the electrochemical stack, electrical energy (e.g., applied voltage) may cause the carbon in the electrolyte solution 201 to be reduced into one or more types of RCPs. The residence time of the CO2-enriched electrolyte stream within the electrochemical stack 202 may be increased inWSGR Docket No.56520-706.601 order to produce larger RCPs. For example, increasing residence time within the electrochemical stack may result in increased production of RCPs with a carbon number greater than C12, for example. In some embodiments, one or more parameters of the electrochemical stack 202 may be adjusted for selectively producing a fuel composition with one or more RCPs. In some embodiments, pH, total inorganic carbon (TIC), flow rate of electrolyte solution (with dissolved CO2), stack dimension, catalyst design, or a combination thereof are adjusted to yield an RCP of a desired size.

[0148] In some cases, allowing RCPs to be retained within the electrochemical stack 202 may allow for their enlargement through the additional of carbon, hydrogen, and oxygen atoms. Enlarged RCPs may have different combustion characteristics as compared to their smaller counterparts. The electrochemical stack 202 may comprise a catalyst. In some embodiments, the first catalyst comprises copper, defect-containing or doped carbon materials, silver palladium, or nickel, or any combination thereof.

[0149] The RCP-enriched electrolyte stream 203 may be directed to an extractor or separation means 204. The extractor 204 may separate RCPs from the electrolyte solution. The RCPs may be removed from the electrolyte solution by heat stripping, gas stripping, or adsorption, or any combination thereof. The electrolyte solution, which may be depleted of RCPs (e.g., depleted electrolyte), may exit the extractor 204 as electrolyte stream 209 back into the DAC unit 210 for additional capture of CO2, so it can be reused within the electrochemical reduction system as described herein. In some embodiments, the electrolyte stream exiting extractor 204 may not be reused within the electrochemical reduction system.

[0150] The RCPs may exit the extractor 204 as RCP stream 205 and enter a separation unit 206. The second separation unit 206 may also be referred to as a split. Within the separation unit 206, RCPs may be separated based on their size. Larger RCPs may be separated from smaller RCPs by a variety of means, including vapor or pervaporation separation methods utilizing carbon nanotube (“CNT”) membranes, hydrocyclones, or adsorption separation, for example. After separation, smaller (e.g., lower molecular weight) RCPs may exit the split 206 as stream 208 and reenter the electrochemical stack 102 to be further reduced. RCPs with an increased carbon number range may exit the split 206 as stream 207 and be used or sold as a finished product or undergo further processing. In some cases, the stream 207 can be sold or used as a finished fuel product, including diesel and jet fuel. Computer systemsWSGR Docket No.56520-706.601

[0151] The present disclosure provides computer systems that are programmed to implement methods of the disclosure. FIG.3 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 the pH within an electrochemical stack, controlling the flow rate of an electrolyte). 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.

[0152] 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.

[0153] 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 theWSGR Docket No.56520-706.601 present disclosure. Examples of operations performed by the CPU 1205 can include fetch, decode, execute, and writeback.

[0154] 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).

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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 (orWSGR Docket No.56520-706.601 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. cloud) 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.

[0160] 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 orWSGR Docket No.56520-706.601 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.

[0161] The computer system 1201 can include or be in communication with an electronic display 1235 that comprises a user interface (UI) 1240 for providing, for example, the pH, flow rates, or temperature of electrolyte streams. Examples of UI’s include, without limitation, a graphical user interface (GUI) and web-based user interface.

[0162] 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 CO2through a direct air capture unit to optimize capture of CO2by 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.

[0163] 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.

[0164] 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. The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. 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,WSGR Docket No.56520-706.601 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.

Claims

WSGR Docket No.56520-706.601 CLAIMS WHAT IS CLAIMED IS:

1. A method for generating a fuel composition, comprising: (a) contacting a gaseous stream comprising carbon dioxide (CO2) with an electrolyte solution to capture at least a subset of the CO2into the electrolyte solution, thereby obtaining an electrolyte solution comprising captured CO2; and (b) in an electrochemical reduction system, reducing the captured CO2to generate a fuel composition comprising a mixture of hydrocarbons, wherein at least 50% of hydrocarbons in the mixture comprise a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the fuel composition.

2. The method of claim 1, wherein the mean number of carbon atoms in the fuel composition is from about 1 to about 40.

3. The method of claim 2, wherein the mean number of carbon atoms in the fuel composition is from about 2 to about 13.

4. The method of claim 2, wherein the mean number of carbon atoms in the fuel composition is from about 8 to about 20.

5. The method of claim 2, wherein the mean number of carbon atoms in the fuel composition is from about 12 to about 24.

6. The method of claim 2, wherein the mean number of carbon atoms in the fuel composition is from about 20 to about 32.

7. The method of claim 2, wherein the mean number of carbon atoms in the fuel composition is from about 18 to about 34.

8. The method of claim 1, wherein at least 70% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition.

9. The method of claim 8, wherein at least 80% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition.

10. The method of claim 9, wherein at least 90% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition.

11. The method of claim 1, wherein at least 50% of hydrocarbons in the mixture are within 3 carbon atoms of the mean number of carbon atoms in the fuel composition.WSGR Docket No.56520-706.601 12. The method of claim 11, wherein at least 50% of hydrocarbons in the mixture are within 1 carbon atoms of the mean number of carbon atoms in the fuel composition.

13. The method of claim 1, wherein the electrochemical reduction system comprises an electrochemical stack.

14. The method of claim 13, wherein the electrochemical stack comprises a surface area.

15. The method of claim 14, wherein the surface area of the electrochemical stack has a positive correlation to the mean number of carbon atoms in the fuel composition.

16. The method of claim 15, wherein a larger surface area yields a higher mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical stack comprising a smaller surface area.

17. The method of claim 1, wherein the electrochemical reduction system operates under a set of one or more parameters selected from the group consisting of: a composition of the electrolyte solution, a temperature of the electrochemical reduction system, a composition of a catalyst in the electrochemical reduction system, a distance between active sites on a catalyst in the electrochemical reduction system, a residence time of the captured CO2in the electrochemical reduction system, a voltage applied to the electrochemical reduction system, a pH of the electrolyte solution, and a concentration of total inorganic carbon (TIC) in the electrolyte solution.

18. The method of claim 17, wherein at least one parameter of the one or more parameters are selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

19. The method of claim 17, wherein the at least one parameter comprises the temperature of the electrochemical reduction system.

20. The method of claim 19, wherein the temperature of the electrochemical reduction system is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

21. The method of claim 20, wherein the temperature of the electrochemical reduction system has a negative correlation to the mean number of carbon atoms in the fuel composition.WSGR Docket No.56520-706.601 22. The method of claim 21, wherein a relatively higher temperature yields a smaller mean number of carbon atoms in the fuel composition than an otherwise similar electrochemical reduction stack operating at a relatively lower temperature.

23. The method of claim 17, wherein the at least one parameter comprises the distance between active sites on the catalyst in the electrochemical reduction system.

24. The method of claim 23, wherein the distance between active sites on the catalyst in the electrochemical reduction system is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

25. The method of claim 24, wherein the distance between active sites on the catalyst in the electrochemical reduction system has a negative correlation to the mean number of carbon atoms in the fuel composition.

26. The method of claim 25, wherein a catalyst comprising a relatively shorter distance between active sites yields a larger mean carbon atom number in the fuel composition than an otherwise similar catalyst comprising a relatively longer distance between active sites.

27. The method of claim 17, wherein the catalyst composition comprises copper, nickel, platinum, iridium, ruthenium, palladium, tin, silver, or gold.

28. The method of claim 17, wherein the at least one parameter comprises the residence time of the captured CO2in the electrochemical reduction system.

29. The method of claim 28, wherein the residence time of the captured CO2in the electrochemical reduction system is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

30. The method of claim 29, wherein the residence time of the captured CO2in the electrochemical reduction system has a positive correlation to the mean number of carbon atoms in the fuel composition.

31. The method of claim 30, wherein a relatively shorter residence time of the captured CO2in the electrochemical reduction system yields a smaller mean carbon atom number in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively longer residence time.WSGR Docket No.56520-706.601 32. The method of claim 17, wherein the at least one parameter comprises the voltage applied to the electrochemical reduction system.

33. The method of claim 32, wherein the voltage is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

34. The method of claim 33, wherein the voltage applied to the electrochemical reduction system has a positive correlation to the mean number of carbon atoms in the fuel composition.

35. The method of claim 34, wherein a relatively higher voltage yields a larger mean carbon atom numbers in the fuel composition than an otherwise similar electrochemical reduction system comprising a relatively lower voltage.

36. The method of claim 17, wherein the at least one parameter comprises the pH of the electrolyte solution.

37. The method of claim 36, wherein the pH of the electrolyte solution is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

38. The method of claim 37, wherein the pH of the electrolyte solution has a positive correlation to the mean number of carbon atoms in the fuel composition.

39. The method of claim 38, wherein a relatively higher pH of the electrolyte solution yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively lower pH.

40. The method of claim 17, wherein the at least one parameter comprises the concentration of the TIC in the electrolyte solution.

41. The method of claim 40, wherein the concentration of the TIC in the electrolyte solution is selected or adjusted to yield the fuel composition comprising the mean number of carbon atoms.

42. The method of claim 41, wherein the concentration of the TIC in the electrolyte solution has a positive correlation to the mean number of carbon atoms in the fuel composition.

43. The method of claim 42, wherein a relatively higher concentration of TIC yields a larger mean carbon atom number in the fuel composition than an otherwise similar electrolyte solution comprising a relatively lower concentration of TIC.WSGR Docket No.56520-706.601 44. The method of claim 1, wherein the electrolyte solution comprising captured CO2comprises carbonate ions, bicarbonate ions, or a combination thereof.

45. The method of claim 44, wherein the captured CO2comprises bicarbonate ions.

46. The method of claim 1, wherein the electrolyte solution comprises water.

47. The method of claim 46, wherein the electrolyte solution further comprises a potassium ion, sodium ion, or a combination thereof.

48. The method of claim 1, wherein the gaseous stream comprises CO2from an atmosphere (e.g., ambient air) or a biological process or an industrial process.

49. The method of claim 1, wherein the gaseous stream comprising CO2comprises air.

50. The method of claim 1, wherein the fuel composition is obtained in absence of distillation.

51. A method for generating a fuel composition, comprising: (a) receiving a request for the fuel composition; and (b) in an electrochemical reduction system, reducing carbon dioxide (CO2) to generate the fuel composition comprising a mixture of hydrocarbons, wherein at least 50% of hydrocarbons in the mixture comprise a number of carbon atoms within 5 carbon atoms of a mean number of carbon atoms in the fuel composition, thereby fulfilling the request.

52. The method of claim 51, wherein the CO2is captured in an electrolyte solution prior to the reducing in (b).

53. The method of claim 51, wherein the request specifies the mean number of carbon atoms in the fuel composition.

54. A method for identifying a source of a fuel composition, comprising measuring a carbon isotope signature of the fuel composition, wherein said carbon isotope signature indicates whether said source comprises atmospheric CO2.

55. The method of claim 54, wherein said carbon isotope signature comprises (i) a ratio of 12C isotope to 13C isotope in said fuel composition, (ii) a concentration of 13C isotope in said fuel composition, or (iii) a concentration of 14C isotope in said fuel composition.

56. The method of claim 54, wherein said carbon isotope signature comprises a ratio of 12C isotope to 13C isotope in said fuel composition.WSGR Docket No.56520-706.601 57. The method of claim 54, wherein said carbon isotope signature comprises a concentration of 13C isotope in said fuel composition.

58. The method of claim 54, wherein said carbon isotope signature comprises a concentration of 14C isotope in said fuel composition.

59. The method of claim 54, wherein said carbon isotope signature indicates whether said source is a fossil fuel or biofuel.

60. The method of claim 54, wherein said carbon isotope signature indicates whether said fuel composition is a carbon neutral fuel.

61. The method of claim 54, wherein said measuring occurs onboard a vehicle configured to operate on said fuel composition.

62. The method of claim 54, wherein said measuring occurs at a pump configured to dispense said fuel composition.

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