A bi-functional reactor and process for co2 reduction and ch4 oxidation

Abstract

A bi-functional reactor and method for producing liquid fuels by reducing CO2 and oxidizing CH4. The reactor includes a vessel having first and second compartments separated by a membrane permeable to water. The first compartment is a catholyte chamber having an inlet, outlet, an electrode for reduction, and catholyte solution. The inlet of the catholyte chamber allows CO2 to flow as a feedstock into the first compartment, while the outlet allows excess CO2 and gaseous reduction products to exit the compartment. The second compartment is an anolyte chamber having an inlet, outlet, an electrode for oxidation, and anolyte solution. The inlet of the anolyte chamber allows CH4 to flow as a feedstock into the second compartment, while the outlet allows excess CH4 and gaseous oxidation products to exit the compartment. CO2 is reduced in the catholyte chamber and CH4 is oxidized in the anolyte chamber to form liquid fuels.

Description

Attorney Docket No.92048-337 A Bi-Functional Reactor and Process for CO2Reduction and CH4Oxidation FIELD

[0001] This invention generally relates to a bi-functional reactor for producing one or more liquid fuels by reducing carbon dioxide CO2and oxidizing methane CH4. More specifically, this disclosure relates to an apparatus and system, as well as a method of using CO2and CH4as a feedstocks to produce liquid fuels. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Both carbon dioxide CO2and methane CH4represent greenhouse gases whose concentration in air needs to be either reduced or removed therefrom. Recently, there is a strong industrial interest in reducing CO2electrochemically into other gases and liquid fuels through the use of renewable electricity generated by solar and wind power technology. In a conventional electrochemical reactor for CO2 reduction, the catholyte contains a carbonate aqueous solution, a working electrode, and a reference electrode. The working electrode in this conventional CO2reduction reactor is generally loaded with a Cu-based catalyst. The anolyte in this conventional electrochemical cell also contains a carbonate aqueous solution along with a counter electrode. During operation, carbon dioxide CO2is reduced at the working electrode, while water is oxidized into O2at the counter electrode. In this type of configuration, the energy consumed at the counter electrode is wasted since the released O2has negligible economic value.

[0004] The oxidation of methane CH4to form liquid fuels is also attractive since CH4is another greenhouse gas that is present in air. In a conventional electrochemical reactor for CH4oxidation, the working electrode is placed in the anolyte chamber along with a reference electrode. The counter electrode is placed in the catholyte chamber. Methane CH4is electrochemically oxidized at the working electrode in the anolyte. The reaction that takes place at the counter electrode in the catholyte reduces water andAttorney Docket No.92048-337 does not generate chemicals having any substantial economic value, in particular this reaction does not generate any useful liquid fuels.

[0005] Thus, in existing CO2reduction reactors and CH4oxidation reactors, the conventional design is to focus on only one chamber, either the catholyte chamber for CO2reduction or the anolyte chamber for CH4oxidation. The function of the other chamber in these conventional designs is to balance the total charge of the system and, therefore, does not result in any significant generation of products that have economic value. Therefore, the need to design new reactors configured to generate products of value is necessary and desirable. SUMMARY

[0006] This disclosure relates generally to an apparatus and system, as well as a method of using CO2and CH4as a feedstocks to produce liquid fuels. More specifically, this disclosure relates to a bi-functional reactor for producing one or more liquid fuels by reducing carbon dioxide CO2and oxidizing methane CH4.

[0007] The bi-functional reactor for producing one or more liquid fuels by reducing carbon dioxide CO2 and oxidizing methane CH4 comprises: a vessel that includes a first compartment and a second compartment separated from one another by a polymeric membrane that is permeable to water. The first compartment is a catholyte chamber having an inlet, an outlet, an electrode for reduction, and a catholyte solution. The inlet of the catholyte chamber is configured to allow CO2to flow there through as a feedstock for the first compartment, while the outlet of the catholyte chamber is configured to allow excess CO2and gaseous reduction products formed therefrom to exit the first compartment. The second compartment is an anolyte chamber having an inlet, an outlet, an electrode for oxidation, and an anolyte solution. The inlet of the anolyte chamber is configured to allow CH4to flow there through as a feedstock for the second compartment, while the outlet of the anolyte chamber is configured to allow excess CH4and gaseous oxidation products formed therefrom to exit the second compartment. The CO2is reduced in the catholyte chamber and the CH4is oxidized in the anolyte chamber to form the one or more liquid fuels.

[0008] According to one aspect of the present disclosure, the catholyte chamber may further comprise a reference electrode. The electrode for reduction in theAttorney Docket No.92048-337 catholyte chamber may be a working electrode, while the electrode for oxidation in the anolyte chamber may be a counter electrode.

[0009] The catholyte solution and the anolyte solution may comprise alkaline aqueous solutions the composition of each being independently selected. Alternatively, the catholyte solution comprises an aqueous solution of hydroxide, bicarbonate or carbonate. Alternatively, the anolyte solution comprises an aqueous solution of hydroxide, bicarbonate or carbonate.

[0010] According to another aspect of the present disclosure, the working electrode in the catholyte chamber may comprise at least one catalyst configured to reduce CO2into the one or more liquid fuels. This at least one catalyst in the working electrode may be selected from the group of copper metal Cu, Cu2O, CuO, and derivatives thereof.

[0011] When desirable, the at least one catalyst in the working electrode may further comprise one or more of amorphous, semi-crystalline, and crystalline carbon, or a dopant containing a second metal element, a non-metal element, or a combination thereof. This dopant may be a non-metal element selected from the group consisting of boron B, nitrogen N, or fluorine F.

[0012] According to another aspect of the present disclosure, the electrode for oxidation may be a counter electrode in the anolyte chamber may comprise at least one catalyst configured to oxidize CH4into the one or more liquid fuels. This at least one catalyst in the electrode for oxidation may be a transition metal oxide or a derivative thereof. Alternatively, the catalyst in the counter electrode may comprise a metal selected from the group consisting of iron Fe, nickel Ni, cobalt Co, and copper Cu.

[0013] According to yet another aspect of the present disclosure, the one or more liquid fuels may comprise alcohols, hydrocarbons, or a combination thereof. The CO2entering the first compartment through the inlet comprises pure CO2or is mixture of CO2and a carrier gas. The CH4entering the first compartment through the inlet comprises pure CH4or is mixture of CH4and a carrier gas. When desirable, the carrier gas may be air. The polymeric membrane in the bi-functional reactor is not permeable to or has limited permeability to the liquid fuels formed in the catholyte and anolyte chambers.Attorney Docket No.92048-337

[0014] The reduction of CO2in the catholyte chamber corresponds to a reaction according to the following equation: 2 CO2 + 9 H2O + 12 e- ^ CH3CH2OH + 12 OH-.

[0015] The oxidation of CH4in the anolyte chamber corresponds to a reaction according to the following equation: 6 CH4+ 12 OH- ^ 6 CH3OH + 6 H2O + 12 e-.

[0016] a method for reducing carbon dioxide CO2and oxidizing methane CH4is provided. This method generally comprises the steps of: providing the bi-functional reactor as described above and as further defined herein; charging the catholyte chamber by allowing CO2to flow through the inlet of the first compartment; charging the anolyte chamber by allowing CH4to flow through the inlet of the second compartment; reducing the CO2in the catholyte chamber and oxidizing the CH4in the anolyte chamber to form one or more liquid fuels; removing gaseous reduction products formed in the catholyte chamber and any excess CO2through the outlet of the first compartment; removing gaseous oxidation products formed in the anolyte chamber and excess CH4through the outlet of the second compartment; and collecting the one or more liquid fuels formed in the catholyte chamber and the anolyte chamber.

[0017] The reduction of CO2in the catholyte chamber and the oxidation of CH4in the anolyte chamber correspond to the following equations: catholyte chamber: 2 CO2+ 9 H2O + 12 e- ^ CH3CH2OH + 12 OH- anolyte chamber: 6 CH4+ 12 OH- ^ 6 CH3OH + 6 H2O + 12 e- with the overall or full reaction that occurs in the bi-functional reactor corresponding to the following equation: 2 CO2+ 6 CH4+ 3 H2O ^ CH3CH2OH + 6 CH3OH.

[0018] the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.Attorney Docket No.92048-337 DESCRIPTION OF THE DRAWINGS

[0019] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings. The components in each of the drawings may not necessarily be drawn to scale, but rather emphasis is placed upon illustrating the principles of the invention.

[0020] Figure 1 is a schematic representation of a bi-functional reactor according to the teachings of the present disclosure.

[0021] Figure 2 provides chemical equations that represent the full reaction that occurs in the bi-functional reactor of Figure 1, as well as the half-reactions that occur in the catholyte chamber and anolyte chamber in the bi-functional reactor.

[0022] Figure 3 is a flowchart illustrating a method for carbon dioxide CO2reduction and methane CH4oxidation in the bi-functional reactor according to the teachings of the present disclosure.

[0023] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. It should be understood that throughout the drawings and corresponding description thereof, corresponding reference numerals indicate like or corresponding parts and features. DETAILED DESCRIPTION

[0024] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. For example, the bi- functional reactor formed and used according to the teachings contained herein are described throughout the present disclosure in relation to the purification of air via the reduction of CO2and the oxidation of CH4impurities in order to more fully illustrate the structural elements and the use thereof. The incorporation and use of such a bi- functional reactor for the oxidation of methane and the reduction of carbon dioxide present in other gas streams, including without limitation, industrial process waste streams wherein the presence of CO2and / or CH4may be a concern, is contemplated to be within the scope of the present disclosure. It should be understood that throughout the description and drawings, corresponding reference numerals indicate like or corresponding parts and features.Attorney Docket No.92048-337

[0025] For the purpose of this disclosure, the terms "about" and "substantially" are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e.g., limitations and variability in measurements).

[0026] For the purpose of this disclosure, the terms "at least one" and "one or more of” an element are used interchangeably and may have the same meaning. These terms, which refer to the inclusion of a single element or a plurality of the elements, may also be represented by the suffix "(s)" at the end of the element. For example, "at least one transition metal", "one or more transition metals", and "transition metal(s)" may be used interchangeably and are intended to have the same meaning.

[0027] The present disclosure generally provides a bi-functional reactor or system, as well as a method of using said bi-functional reactor in the reduction of carbon dioxide CO2and the oxidation of methane CH4. Referring to Figure 1, a bi-functional reactor 1 for producing one or more liquid fuels by reducing carbon dioxide CO2and oxidizing methane CH4is provided. The bi-functional reactor 1 generally comprises: a vessel 5 that includes a first compartment 7 and a second compartment 8 separated from one another by a polymeric membrane 9 that is permeable to water.

[0028] The first compartment 7 is a catholyte chamber 13 that comprises an inlet 15, an outlet 17, an electrode for reduction 19, which may be a working electrode (WE), and a catholyte solution 23. When the electrode for reduction 19 is a working electrode (WE), the catholyte chamber 13 may also include a reference electrode 21. The inlet 15 of the catholyte chamber 13 is configured to allow and does allow CO2to flow there through as a feedstock for the first compartment 7. The outlet 17 of the catholyte chamber 13 is configured to allow and does allow excess CO2and gaseous reduction products formed from the reduction of carbon dioxide to exit the first compartment 7. The reduction of CO2in the catholyte chamber 13 also forms one or more liquid fuels 25, such as for example alcohol(s), hydrocarbon(s), or a combination thereof.

[0029] The second compartment 8 is an anolyte chamber 10 that comprises an inlet 12, an outlet 14, an electrode for oxidation 16, and an anolyte solution 18. When necessary or desirable, the electrode for oxidation 16 may be configured as a counter electrode (CE). The inlet 12 of the anolyte chamber 10 is configured to allow and does allow CH4to flow there through as a feedstock for the second compartment 8. The outlet 14 of the anolyte chamber 10 is configured to allow and does allow excess CH4Attorney Docket No.92048-337 and gaseous oxidation products formed from the oxidation of methane to exit the second compartment 8. The oxidation of CH4in the anolyte chamber 10 also forms one or more liquid fuels 26, such as for example alcohol(s), hydrocarbon(s), or a combination thereof.

[0030] Still referring to Figure 1, the bi-functional reactor 1 uses both CO2and CH4as feedstock gases. More specifically, in this bi-functional reactor, carbon dioxide CO2is fed into the catholyte chamber 13 and methane CH4is fed to the anolyte chamber 10. The concentration of the feedstock gases, i.e., CO2and CH4, are independently selected and may range from being pure CO2and / or CH4to being mixed with air or a carrier gas, such as without limitation air / CO2and air / CH4with the ratio of air:CO2and air:CH4being any ratio. The carrier gas may be a gas other than air without exceeding the scope of the present disclosure. Alternatively, the carrier gas is air. When desirable, the amount of CO2in the mixture with air is greater than about 1% by weight; alternatively, greater than about 5% by weight; alternatively, greater than about 15% by weight; alternatively, greater than about 25% by weight; alternatively, greater than about 400 ppm. Alternatively, the amount of CH4in the mixture with air is greater than about 1% by weight; alternatively, greater than about 5% by weight; alternatively, greater than about 15% by weight; alternatively, greater than about 25% by weight; alternatively, greater than about 1.5 ppm.

[0031] The electrode of reduction 19 or working electrode (WE) is placed in the catholyte solution 23 for CO2reduction since the potential needs to be monitored accurately. As for the electrode for oxidation 16 or counter electrode (CE), it is placed in the anolyte solution 18 for the oxidation of CH4. The oxidation potential of CH4is slightly lower than the oxidation potential for the decomposition of water. Thus, the CH4oxidation reaction is expected to start earlier than the reaction resulting in the decomposition of water. Even in the absence of potential monitoring, the electrode for oxidation 19 or counter electrode (CE) will oxidize CH4prior to the occurrence of water decomposition.

[0032] During the operation of the bi-functional reactor 1, carbon dioxide CO2is reduced in the catholyte chamber 13 to produce gases and / or liquid fuels, while methane CH4is oxidized simultaneously in the anolyte chamber 10 to also produce gases and / or liquid fuels. In particular, the bi-functional reactor 1 system is efficient for generating liquid fuels in both chambers 10, 13 since hydrocarbons and / or alcoholsAttorney Docket No.92048-337 may be generated by CO2reduction and by CH4oxidation upon the use of the right catalyst materials. In comparison, conventional reactors are designed for the occurrence of only one reaction, e.g., either the reduction of carbon dioxide or the oxidation of methane.

[0033] The benefits associated with the bi-functional reactor 1 of the present disclosure include, without limitation, the removal of both CO2and CH4from air, an increase in the production of liquid fuel sources, and the reduction of both operating costs (e.g., electricity, etc.) and capital equipment costs. Since both carbon dioxide and methane are greenhouse gases it is highly effective to remove them from air simultaneously. Instead of the need to invest in two separate reactor systems, now a single bi-functional reactor system can perform the same function.

[0034] In a conventional reactor design, six electrons are necessary to reduce carbon from C4+in CO2into C2-in ethyl alcohol CH3CH2OH in the catholyte solution. In the bi-functional reactor, the same amount of alcohol may be produced in the catholyte chamber 13 with six electrons via the reduction of carbon dioxide. However, simultaneously, the anolyte chamber 10 will provide six electrons via the oxidation of CH4at the counter electrode (CE). During methane CH4oxidation, the oxidation state of carbon C changes from -4 to -2 resulting in the formation of methanol CH3OH, along with 2 electrons. To achieve a total of six electrons needed for the reduction of a mole of carbon dioxide in the catholyte chamber 13, there should be three times (3x) the number of moles of methane CH4oxidized in the anolyte chamber 10.

[0035] Referring now to Figure 2 and the equations set forth below, the reactions in each of the catholyte and anolyte chambers for the generation of alcohols along with the full reaction that occurs in the bi-functional reactor is provided.

[0036]

[0037] Upon the selection and use of appropriate catalysts in the electrode of reduction 19 or working electrode (WE) and in the electrode for oxidation 16 or counter electrode (CE), a total of six (6) moles of methanol is produced from CH4oxidation, with one (1) mole of ethanol being simultaneously produced from CO2reduction. The product yield of alcohol (methanol + ethanol) is significantly increased by introducingAttorney Docket No.92048-337 CH4into the counter electrode for the CO2reduction reactor, which significantly lowers the production cost of the alcohol(s).

[0038] The reduction catalyst used in the electrode for reduction 19 or working electrode (WE) of the catholyte chamber may be any catalyst developed for or known to be used for the electrochemical reduction of CO2into one or more liquid fuels. This catalyst may be based on, but not limited to, Cu, Cu2O, CuO, and derivatives thereof. The Cu-based catalysts may have a carbon content in the range of 0.1 to 99 wt.%. This carbon can be amorphous, semi-crystalline, crystalline, or a mixture thereof. The reduction catalyst used in the electrode for reduction 19 or working electrode (WE) may be a bimetallic catalyst that comprises at least one other metal selected from the periodic element table. The reduction catalyst may also be doped with one or more non-metal elements, such as, for example, boron B, nitrogen N, or fluorine F.

[0039] The oxidation catalyst used in the electrode for oxidation 16 or counter electrode (CE) of the anolyte chamber may be any catalyst developed for or known to be used for the electrochemical oxidation of CH4into one or more liquid fuels. This catalyst may include, but not be limited to, metal oxides, such as, for example, a transition metal oxide or a derivative thereof. The oxidation catalyst when desired may be a transition metal oxide / ZrO2nanocomposite. The transition metal may include, without limitation, iron Fe, nickel Ni, cobalt Co, copper Cu, or a mixture thereof.

[0040] The liquid fuels formed from the oxidation of methane and the reduction of carbon dioxide may include, but not be limited to, alcohols, hydrocarbons, or a combination thereof. Alternatively, the liquid fuels formed in the catholyte chamber and the anolyte chamber are alcohols. The composition of the liquid fuel formed in the catholyte chamber and the anolyte chamber may be the same or different; alternatively, the liquid fuels formed are different. For example, as shown in Figure 2, ethyl alcohol is shown to be formed in the catholyte chamber, while methanol is shown to be formed in the anolyte chamber.

[0041] The catholyte solution is the electrolyte that provides water and the dissolved CO2for the reduction reaction. The CO2is bubbled through the catholyte solution and dissolves therein. The dissolved CO2molecules diffuse into the electrode for reduction 19 or working electrode (WE) and are reduced by the catalyst particles contained therein. A high solubility of CO2is expected for this electrolyte. In general, the catholyte solution may comprise an alkaline aqueous solution. The catholyte may,Attorney Docket No.92048-337 without limitation, be a bicarbonate and / or carbonate aqueous electrolyte. The catholyte solution may also contain one or more salts in various concentrations. When desirable, this salt may be potassium hydroxide KOH. In order to increase the solubility of CO2in the catholyte solution, a flow cell design may be used in which the contact area between the flowing CO2gas and the catalyst is increased. Thus, the catholyte solution utilized in the bi-functional reactor, may comprise any conventional catholyte solution, as well as be formed of other aqueous mixtures or solutions that exhibit a high CO2.

[0042] The anolyte solution serves the same function as the catholyte solution with respect to providing water and dissolved CH4for the oxidation reaction. Thus, the anolyte solution may also comprise an alkaline aqueous solution. The anolyte solution may be, without limitation, an aqueous solution of hydroxides, bicarbonate and / or carbonate; alternatively, the anolyte solution is an aqueous carbonate solution. The composition of the anolyte solution may be the same or independently selected from the composition of the catholyte solution.

[0043] In order to avoid the cross-over of the reduced / oxidized species present in the catholyte and anolyte solutions, the membrane provides a barrier to such exchange. Thus, the membrane is not permeable to or has limited permeability to the liquid fuels formed in the catholyte and anolyte chambers. This membrane may be, but not limited to, an ionic exchange membrane. This membrane may be a Nafion™ membrane (The Chemours Company) or any other polymer-based membrane.

[0044] The bi-functional reactor may be constructed with a catholyte chamber and anolyte chamber having a volume predetermined based upon amount of CO2and CH4intended to be reduced and oxidized, respectively. This predetermined volume may, without limitation, be any volume relative to milliliters or liters. For example, each of the catholyte and anolyte chambers may have a volume in the range of about 250 milliliters (mL) to 1,000 liters; alternatively, the volume is between 500 mL and 500 liters; alternatively, between 5 liters and 100 liters; alternatively, greater than 1 liter. The size of the catholyte chamber and the anolyte chamber may be the same or selected to have a different volume.

[0045] The bi-functional reactor may be made from a metal, plastic, ceramic, or a combination thereof provided that the vessel can withstand exposure to the catholyte and anolyte solutions, as well as the reduction products and oxidation products formedAttorney Docket No.92048-337 therein, respectively. The catholyte and anolyte chambers may be formed of the same material or a different material. The construction of the bi-functional reactor should be able to be operated at atmospheric pressure or up to a pressure of about 500 psi and from a temperature of ambient temperature (e.g., about 22°C) up to a temperature of about 75°C. Alternatively the pressure to which the bi-functional reactor is exposed may be between atmospheric pressure and 500 psi; alternatively between 100 psi and about 450 psi. The temperature may further be between room temperature and 50°C; alternatively, between about 30°C and about 50°C. In addition, the materials used in the construction of the bi-functional reactor should be chemically resistant to the degradation of its physical properties in the presence of the electrolyte solution under the pressure and temperature conditions employed.

[0046] The bi-functional reactor may further comprise a control system (not shown) that is configured to control one or more of temperature or pressure in the reactor; the flow rate for the CO2and CH4flowing through the apparatus; and for measuring the predetermined amount of the gases dissolved in the catholyte and anolyte solutions present in the bi-functional reactor. This control system may include a controller or computer along with corresponding software capable of monitoring sensors (e.g., pressure, temperature, flow rate, etc.) positioned within the bi-functional reactor and for controlling the operation of various components within the reactor system.

[0047] According to yet another aspect of the present disclosure, a method is provided for reducing carbon dioxide CO2and oxidizing methane CH4in the bi- functional reactor as described above and further defined herein. Referring now to Figure 3, this method 150 generally comprises the steps of: providing 155 the bi- functional reactor; charging the catholyte chamber 160 by allowing CO2to flow through the inlet of the first compartment; charging the anolyte chamber 165 by allowing CH4to flow through the inlet of the second compartment; reducing the CO2in the catholyte chamber and oxidizing the CH4in the anolyte chamber 170 to form one or more liquid fuels; removing 175 gaseous reduction products formed in the catholyte chamber and any excess CO2through the outlet of the first compartment; removing 180 gaseous oxidation products formed in the anolyte chamber and excess CH4through the outlet of the second compartment; and collecting 185 the one or more liquid fuels formed in the catholyte chamber and the anolyte chamber.Attorney Docket No.92048-337

[0048] The specific reactions that occur in the catholyte chamber and in the anolyte chamber of the bi-functional reactor may comprise, without limitation, the half- reactions shown in Figure 2 leading to the production of an alcohol in each of the chambers through the oxidation of methane and the reduction of carbon dioxide.

[0049] The bi-functional reactor 1 described in the specification and figures is provided as one specific example of such a reactor 1. One skilled in the art understands that modifications can be made to the bi-functional reactor 1 without departing from the scope of the present invention. For example, a commercial application, the bi-functional reactor may be modified such that a reference electrode is avoided. More specifically, the bi-functional reactor 1 could comprise only two electrodes, e.g., with one electrode in the anolyte chamber and the other electrode in the catholyte chamber. The electrode in the anolyte chamber being used to provide electrons to reduce CO2, while the electrode in the catholyte is used to extract electrons to oxidize CH4. The power controlling protocols may be varied, but the underlying concept is the same, which is to reduce CO2in one chamber and oxidize CH4simultaneously in the other or second chamber.

[0050] The specific examples provided in this disclosure are given to illustrate various embodiments of the invention and should not be construed to limit the scope of the disclosure. The embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0051] Those skilled-in-the-art, in light of the present disclosure, will appreciate that many changes can be made in the specific embodiments which are disclosed herein and still obtain alike or similar result without departing from or exceeding the spirit or scope of the disclosure. One skilled in the art will further understand that any properties reported herein represent properties that are routinely measured and can be obtained by multiple different methods. The methods described herein represent one such method and other methods may be utilized without exceeding the scope of the present disclosure.

[0052] The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to beAttorney Docket No.92048-337 exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

Attorney Docket No.92048-337 CLAIMS What is claimed is:

1. A bi-functional reactor for producing one or more liquid fuels by reducing carbon dioxide CO2and oxidizing methane CH4; the bi-functional reactor comprising: a vessel that includes a first compartment and a second compartment separated from one another by a polymeric membrane; the polymeric membrane being permeable to water; the first compartment being a catholyte chamber having an inlet, an outlet, an electrode for reduction, and a catholyte solution; the inlet of the catholyte chamber being configured to allow CO2to flow there through as a feedstock for the first compartment; the outlet of the catholyte chamber being configured to allow excess CO2and gaseous reduction products formed therefrom to exit the first compartment; the second compartment being an anolyte chamber having an inlet, an outlet, an electrode for oxidation, and an anolyte solution; the inlet of the anolyte chamber being configured to allow CH4to flow there through as a feedstock for the second compartment; the outlet of the anolyte chamber being configured to allow excess CH4and gaseous oxidation products formed therefrom to exit the second compartment’ wherein CO2is reduced in the catholyte chamber and CH4is oxidized in the anolyte chamber to form the one or more liquid fuels.

2. The bi-functional reactor according to claim 1, wherein the catholyte chamber further comprises a reference electrode.

3. The bi-functional reactor according to Claim 2, wherein the electrode for reduction in the catholyte chamber is a working electrode.

4. The bi-functional reactor according to any of claims 1-3, wherein the catholyte solution and the anolyte solution comprise alkaline aqueous solutions the composition of each being independently selected.Attorney Docket No.92048-337 5. The bi-functional reactor according to any of claims 1 to 4, wherein the catholyte solution comprises an aqueous solution of hydroxide, bicarbonate or carbonate.

6. The bi-functional reactor according to any of claims 1 to 5, wherein the anolyte solution comprises an aqueous solution of hydroxide, bicarbonate or carbonate.

7. The bi-functional reactor according to any of claims 1 to 6, wherein the working electrode in the catholyte chamber comprises at least one catalyst configured to reduce CO2into the one or more liquid fuels.

8. The bi-functional reactor according to claim 7, wherein the at least one catalyst in the working electrode is selected from the group of copper metal Cu, Cu2O, CuO, and derivatives thereof.

9. The bi-functional reactor according to any of claims 7 or 8, wherein the at least one catalyst in the working electrode further comprises one or more of amorphous, semi-crystalline, and crystalline carbon, or a dopant containing a second metal element, a non-metal element, or a combination thereof.

10. The bi-functional reactor according to claim 9, wherein the dopant is a non- metal element selected from the group consisting of boron B, nitrogen N, or fluorine F.

11. The bi-functional reactor according to any of claims 2 or 3, wherein the electrode for oxidation is a counter electrode.

12. The bi-functional reactor according to any of claims 1 to 11, wherein the electrode for oxidation in the anolyte chamber comprises at least one catalyst configured to oxidize CH4into the one or more liquid fuels.Attorney Docket No.92048-337 13. The bi-functional reactor according to claim 12, wherein the at least one catalyst in the electrode for oxidation is a transition metal oxide or a derivative thereof.

14. The bi-functional reactor according to any of claims 12 or 13, wherein the catalyst in the counter electrode comprises a metal selected from the group consisting of iron Fe, nickel Ni, cobalt Co, and copper Cu.

15. The bi-functional reactor according to any of claims 1 to 14, wherein the one or more liquid fuels comprise alcohols, hydrocarbons, or a combination thereof.

16. The bi-functional reactor according to any of claims 1 to 15, wherein the CO2entering the first compartment through the inlet comprises pure CO2or is mixture of CO2and a carrier gas.

17. The bi-functional reactor according to any of claims 1 to 16, wherein the CH4entering the first compartment through the inlet comprises pure CH4 or is mixture of CH4and a carrier gas.

18. The bi-functional reactor according to any of claims 16 or 17, where the carrier gas is air.

19. The bi-functional reactor according to any of claims 1 to 18, wherein the polymeric membrane is not permeable to or has limited permeability to the liquid fuels formed in the catholyte and anolyte chambers.

20. The bi-functional reactor according to any of claims 1 to 19, wherein the reduction of CO2in the catholyte chamber corresponds to a reaction according to the following equation: 2 CO2+ 9 H2O + 12 e- ^ CH3CH2OH + 12 OH-.Attorney Docket No.92048-337 21. The bi-functional reactor according to any of claims 1 to 20, wherein the oxidation of CH4in the anolyte chamber corresponds to a reaction according to the following equation: 6 CH4+ 12 OH- ^ 6 CH3OH + 6 H2O + 12 e-.

22. A methodmethane CH4; the method comprising the steps of: providing the bi-functional reactor according to any of Claims 1 to 21; charging the catholyte chamber by allowing CO2to flow through the inlet of the first compartment; charging the anolyte chamber by allowing CH4to flow through the inlet of the second compartment; reducing the CO2in the catholyte chamber and oxidizing the CH4in the anolyte chamber to form one or more liquid fuels; removing gaseous reduction products formed in the catholyte chamber and any excess CO2through the outlet of the first compartment; removing gaseous oxidation products formed in the anolyte chamber and excess CH4through the outlet of the second compartment; and collecting the one or more liquid fuels formed in the catholyte chamber and the anolyte chamber.

23. The method according to claim 22, wherein the reduction of CO2in the catholyte chamber and the oxidation of CH4in the anolyte chamber correspond to the following equations: catholyte chamber: 2 CO2+ 9 H2O + 12 e- ^ CH3CH2OH + 12 OH- anolyte chamber: 6 CH4+ 12 OH- ^ 6 CH3OH + 6 H2O + 12 e- with the overall or full reaction that occurs in the bi-functional reactor corresponding to the following equation: 2 CO2+ 6 CH4+ 3 H2O ^ CH3CH2OH + 6 CH3OH.

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