Integrated processes for producing olefinic products from carbon dioxide

Abstract

Olefinic products may be produced from various sources. For example, methods of production of olefinic products from carbon dioxide may include: performing an electrolysis reaction of water to form hydrogen and oxygen; providing at least a portion of the hydrogen and carbon dioxide to a methanation unit; reacting the hydrogen and the carbon dioxide via a methanation reaction in the methanation unit to produce methane and water; providing at least a portion of the methane and at least a portion of the oxygen to an oxidative coupling unit; and reacting the methane and the oxygen via an oxidative coupling reaction in the oxidative coupling unit to produce an olefinic product, water, and optionally, additional carbon dioxide.

Description

INTEGRATED PROCESSES FOR PRODUCING OLEFINIC PRODUCTS FROM CARBON DIOXIDECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 652,839 having a filing date of May 29, 2024, the disclosure of which is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates to systems and methods for producing olefinic products from carbon dioxide.BACKGROUND

[0003] There is growing interest in energy-efficient processes that either sequester carbon dioxide or convert the carbon dioxide into a more benign form for storage or further utilization as a high-value material.SUMMARY

[0004] Methods of the present disclosure may comprise: performing an electrolysis reaction of water to form hydrogen and oxygen; providing at least a portion of the hydrogen and carbon dioxide to a methanation unit; reacting the hydrogen and the carbon dioxide via a methanation reaction in the methanation unit to produce methane and water; providing at least a portion of the methane and at least a portion of the oxygen to an oxidative coupling unit; and reacting the methane and the oxygen via an oxidative coupling reaction in the oxidative coupling unit to produce an olefinic product, water, and optionally, additional carbon dioxide.

[0005] Systems of the present disclosure may comprise: an electrolysis unit configured to flow an electric current through water to electrolyze the water and produce hydrogen and oxygen therefrom; a methanation unit configured to receive at least a portion of the hydrogen from the electrolysis unit and a first portion of carbon dioxide from an external source, and to react the hydrogen and the carbon dioxide via a methanation reaction to produce methane and water; an oxidative coupling unit configured to receive at least a portion of the oxygen from the electrolysis unit and at least a portion of the methane from the methanation unit, and to react the methane and the oxygen via an oxidative coupling reaction to produce an olefinic product, water, and optionally, an additional portion of carbon dioxide; and a line configured to withdraw the olefinic product from the oxidative coupling unit.

[0006] These and other features and attributes of the disclosed methods and systems of the present disclosure and their advantageous applications and / or uses will be apparent from the detailed description which follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawing. The following figure is included to illustrate certain aspects of the disclosure, and should not be viewed as an exclusive configuration. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0008] The FIGURE is a diagram of an illustrative method and system according to the present disclosure.DETAILED DESCRIPTION

[0009] The present disclosure relate to systems and methods for producing olefinic products from carbon dioxide.

[0010] There is considerable room for improvement of operating efficiencies for converting carbon dioxide into other products of value, such as olefinic products. To accomplish the foregoing, the present disclosure provides integrated systems and methods that may couple multiple chemical reactions together in a manner to promote energy-efficient conversion of carbon dioxide into olefinic products having higher value. Further transfer of heat between the coupled chemical reactions may further improve operating efficiencies as well.

[0011] More particularly, the present disclosure provides integrated systems and methods in which electrolysis of water, methanation, and oxidative coupling of methane are coupled together to promote integrated production of olefinic products. As described in further detail hereinafter, the integrated systems and methods of the present disclosure may provide a sink for withdrawal of carbon dioxide from an external source (e.g., the atmosphere, an industrial process, and / or a storage location) and further convert the carbon dioxide into olefinic products having a higher monetary value. Advantageously, the exothermicity of the methanation reaction and the oxidative coupling of methane reaction may be leveraged to provide heating to the endothermic water electrolysis reaction to improve or drive the electrolysis process. Further, lower-carbon generation sources of electricity may be utilized to conduct the electrolysis reaction to provide additional benefits.

[0012] Electrolysis of water produces hydrogen and oxygen as products. Electrolysis of water is a conventionally endothermic reaction and may favor additional heat input in additionto electric current to drive the reaction. Advantageously, the endothermic water electrolysis process may be thermally coupled to the methanation reaction and the oxidative coupling of methane reaction, both of which are exothermic and may provide excess heat to help drive and increase the efficiency of the water hydrolysis reaction.

[0013] Methanation refers to a reaction that converts carbon oxides (e.g., carbon dioxide and / or carbon monoxide) into methane and water in the presence of hydrogen. Methanation may produce synthetic natural gas. In the disclosure herein, at least a portion of the carbon dioxide for conducting the methanation reaction may be captured from a suitable external source (e.g., the atmosphere, an industrial process, a storage location, and / or the like) and may undergo conversion into methane and water. Rather than being withdrawn as a natural gas product itself, all or a substantial majority of the methane obtained from the methanation reaction may be provided directly to the oxidative coupling reaction for conversion to an olefinic product. In addition, for complete process integration, water produced from the methanation reaction may be obtained in the form of heated water and / or steam, which may be provided to the electrolysis reaction to supplement the quantity of water undergoing electrolysis and deliver excess heat from the methanation reaction to the electrolysis reaction to improve the operating efficiency of the latter. The methanation reaction may occur catalytically, as described in further detail below.

[0014] Oxidative coupling of methane (OCM) refers to a reaction that converts methane to olefinic products, water, and optionally carbon dioxide in the presence of oxygen. Olefinic products may include C2-C4 alkenes, for example, such as ethylene, propylene, butylenes (e.g., 1 -butene, 2-butene, and / or isobutylene), or any combination thereof. In the disclosure herein, the olefinic products may be withdrawn from the oxidative coupling reaction as a value product. For complete process integration, carbon dioxide (if produced) from the oxidative coupling reaction may be provided to the methanation reaction to supplement other carbon dioxide being provided to this reaction from an external source (e.g., environmental carbon dioxide, industrial process carbon dioxide, and / or a reservoir of enriched carbon dioxide). In addition, water produced from the oxidative coupling reaction may be obtained in the form of heated water and / or steam, which may be provided to the electrolysis reaction to supplement the quantity of water undergoing electrolysis and deliver excess heat from the oxidative coupling reaction to the electrolysis reaction to improve the operating efficiency of the latter. The oxidative coupling reaction may occur catalytically, as described in further detail below.

[0015] Systems and methods of the present disclosure will now be described with reference to the drawings. The FIGURE is a diagram of a nonlimiting example of a system and methodaccording to the present disclosure. System and method 100 includes electrolysis unit 110, methanation unit 130, and oxidative coupling unit 150. Electrolysis unit 110, methanation unit 130, and oxidative coupling unit 150 are mutually fluidly coupled with one another to provide and receive reaction products therefrom, as described in greater detail hereinafter.

[0016] Electrolysis unit 110 may receive electricity 102 and aqueous fluid 104 (e.g., water) and subsequently produce hydrogen 114 and oxygen 112, 116 via an electrolysis reaction of aqueous fluid 104. Oxygen 112, 116 may be produced in two portions, as shown, or oxygen 112 may be omitted so that all of the electro lytically produced oxygen 116 is provided to oxidative coupling unit 150. Oxygen 112 may represent excess oxygen beyond that needed to conduct the oxidative coupling reaction in oxidative coupling unit 150. If excess oxygen is produced, oxygen 112 may be provided to an external location (e.g., a separate industrial process, a storage tank, and / or the like) or simply vented to the atmosphere.

[0017] Hydrogen 114 is provided from electrolysis unit 110 to methanation unit 130. Methanation unit 130 may further receive carbon dioxide 122 from an external source (e.g., atmospheric carbon dioxide and / or a carbon dioxide reservoir, such as a tank, or an industrial process) and preferably carbon dioxide 156 from oxidative coupling unit 150, as discussed subsequently. Upon conducting a methanation reaction under methanation reaction conditions in methanation unit 130, methane 134 and water 132 are produced. As shown, water 132 may be provided to electrolysis unit 110 to transfer heat thereto, as well as supplement the water undergoing the electrolysis reaction therein. Water 132 may be transferred from methanation unit 130 as steam, heated water, or any combination thereof to electrolysis unit 110 to aid in promoting the endothermic electrolysis reaction occurring therein. Optionally, all or a portion of water 132 may be diverted from electrolysis unit 110 and removed from system and method 100, if needed, to aid in regulating the temperature at which the electrolysis reaction occurs.

[0018] Methane 134 from methanation unit 130 and oxygen 116 from electrolysis unit 110 are provided to oxidative coupling unit 150. Upon conducting an oxidative coupling reaction of methane under oxidative coupling reaction conditions in oxidative coupling unit 150, olefinic products 154, water 152, and optionally carbon dioxide 156, are produced as reaction products of the oxidative coupling reaction. As shown, olefinic products 154 are withdrawn from system and method 100, and carbon dioxide 156 (if produced) is provided to methanation unit 130 as a second portion of carbon dioxide to supplement carbon dioxide 122 introduced from another source. Water 152 may be provided to electrolysis unit 110 to transfer heat thereto, as well as supplement the water undergoing the electrolysis reaction therein. Water 152 may be transferred to electrolysis unit 110 as steam, heated water, or any combinationthereof from oxidative coupling unit 150 to aid in promoting the endothermic electrolysis reaction occurring therein. All or a portion of water 152 may be diverted from electrolysis unit 110 and removed from system and method 100, if needed, to aid in regulating the temperature at which the electrolysis reaction occurs.

[0019] It is to be appreciated that the FIGURE has depicted system and method 100 in a simplified form. System and method 100 may incorporate valves, pumps, heaters, chillers, flow lines, inlets, outlets, and similar equipment to facilitate the fluid transfers and reactions taking place therein. Having the benefit of the present disclosure, one of ordinary skill in the art will be able introduce suitable components to accomplish the foregoing.

[0020] Accordingly, methods of the present disclosure may comprise: performing an electrolysis reaction of water to form hydrogen and oxygen; providing at least a portion of the hydrogen and carbon dioxide to a methanation unit; reacting the hydrogen and the carbon dioxide via a methanation reaction in the methanation unit to produce methane and water; providing at least a portion of the methane and at least a portion of the oxygen to an oxidative coupling unit; and reacting the methane and the oxygen via an oxidative coupling reaction in the oxidative coupling unit to produce an olefinic product, water, and optionally, additional carbon dioxide. Preferably, the additional carbon dioxide, if produced (or produced in sufficient quantity), may also be provided to the methanation unit, such that the carbon dioxide provided to the methanation unit comprises a first portion of carbon dioxide obtained from an external source and a second portion of carbon dioxide obtained from the additional carbon dioxide. More preferably, all or substantially all of the additional carbon dioxide is provided to the methanation unit. The first portion of carbon dioxide from the external source and the second portion of carbon dioxide from the additional carbon dioxide produced in the oxidative coupling reaction may be provided to the methanation unit in any suitable ratio, including ratios whereby all or substantially all of the carbon dioxide provided to the methanation unit originates from either the external source or the additional carbon dioxide. Preferably, at least a majority of the carbon dioxide provided to the methanation unit originates from the external source.

[0021] The electrolysis reaction may take place by flowing an electric current through water or an aqueous fluid in an electrolysis unit to produce oxygen and hydrogen. Aqueous fluids suitable for undergoing electrolysis may include for example, water, brine, seawater, aqueous salt solutions, the like, or any combination thereof. Preferably, the aqueous fluid may lack other species capable of undergoing oxidation or reduction under the electrolysis conditions. In more specific embodiments, the electrolysis reaction may be conducted in a solid oxideelectrolysis cell (SOEC) featuring a solid oxide electrolyte that may catalyze the electrolysis reaction. Suitable solid oxide electrolytes may include, but are not limited to, zirconium dioxide (ZrCh), yttrium oxide (Y2O3), the like, or any combination thereof. One of ordinary skill in the art will be able to select an appropriate solid oxide electrolyte in order to conduct and realize the benefits of the disclosure herein.

[0022] Electrolysis of water in the presence of a solid oxide electrolyte may occur at an elevated temperature, such as a temperature of about 50°C to about 1000°C, or about 50°C to about 500°C, or about 500°C to about 850°C, or about 750°C to about 1000°C. The electrolysis unit may be heated in order to promote the electrolysis reaction occurring therein. The heating may take place using a heater (e.g. , a resistive heater, a solar heater, a circulating air heater, or the like), or heated fluids from elsewhere in a plant facility may be utilized to heat the electrolysis unit. Preferably, heat may be transferred from the exothermic reactions occurring in the methanation unit and / or the oxidative coupling unit to heat the electrolysis unit and promote the electrolysis reaction occurring therein, such as by conveying heated water and / or steam from the oxidative coupling unit and / or the methanation unit to the electrolysis unit. Heating with the heated water and / or steam may simply heat the electrolysis unit (e.g., by indirect, jacketed heating of the electrolysis unit), or more preferably, the heated water and / or steam may supplement the water undergoing the electrolysis reaction within the electrolysis unit, thereby providing direct heating thereto. That is, the heated water and / or steam may be introduced into the electrolysis unit, thereby undergoing the electrolysis reaction themselves and providing direct heating to promote the electrolysis reaction. In non-limiting examples, a first portion of steam may be obtained from the methanation reaction occurring in the methanation unit, and a second portion of steam may be obtained from the oxidative coupling reaction occurring in the oxidative coupling unit, wherein the first portion and the second portion of steam are conveyed to the electrolysis unit to accomplish the foregoing.

[0023] Within the electrolysis unit, the electrolysis reaction to produce hydrogen and oxygen may occur according to the half-reactions shown in Reactions 1 and 2 below, wherein Reaction 1 occurs at the cathode and Reaction 2 occurs at the anode. The overall reaction is shown in Reaction 3. Reactions 1 and 2 occur under acidic conditions. Analogous half-reactions may occur under basic conditions, with the same overall reaction being realized in either case.4H++ 4e -> 2H2Reaction 12H2O -> O2+ 4H++ 4e~ Reaction 22H2O -> 2H2+ O2Reaction 3The overall reaction (Reaction 3) is endothermic and has a standard enthalpy of reaction of about +285.83 kJ / mol.

[0024] Electric current may be used to drive the electrolysis reaction occurring in the electrolysis unit. While any source of electrical energy may be used, the electrical energy for providing the electric current may preferably originate from a lower-carbon generation source to maintain environmental favorability of the processes described herein. As used herein, the term “lower-carbon generation source” and grammatical variations thereof refer to an electricity generation source or process having direct carbon dioxide emissions of about 0.3 tons CO2 or less per MWh of electricity. In non-limiting examples, the lower-carbon generation source may have direct carbon dioxide emissions of about 0.3 tons CO2 or less per MWh of electricity, or about 0.2 tons CO2 or less per MWh of electricity, or about 0.1 tons CO2 or less per MWh of electricity, such as about 0.01 tons CO2 per MWh of electricity to about 0.3 tons CO2 per MWh of electricity, or about 0.01 tons CO2 per MWh of electricity to about 0.2 tons CO2 per MWh of electricity, or about 0.01 tons CO2 per MWh of electricity to about 0.1 tons CO2 per MWh of electricity. Examples of lower-carbon generation sources may include, but are not limited to, nuclear energy, solar energy, wind energy, hydroelectric energy, geothermal energy, the like or any combination thereof.

[0025] Methanation may occur under methanation reaction conditions in a methanation unit, wherein a carbon oxide (e.g., carbon dioxide, carbon monoxide, or any combination thereof) and hydrogen may be converted to methane and water. Any suitable reaction vessel may be used to conduct a methanation reaction in accordance with the present disclosure. Methanation of carbon dioxide and / or carbon monoxide may be promoted using a suitable catalyst. Examples of catalysts suitable for promoting methanation may include, but are not limited to, nickel-based catalysts (e.g., Ni / AhCh), ruthenium-based catalysts (e.g., RU / AI2O3, or Ru / C), rhodium-based catalysts, palladium-based catalysts (e.g., Pd / ZnO / AI2O3, or Pd / ZnO), the like, or any combination thereof. In the presence of a suitable catalyst and solvent (if used), the methanation reaction may occur under methanation reaction conditions including any suitable temperature and pressure, such as a temperature of about 150°C to about 400°C, or about 300°C to about 400°C. Methanation reactions of carbon monoxide and carbon dioxide are shown in Reactions 4 and 5 below.CO + 3H2-> CH4+ H2O Reaction 4CO2+ 4H2-> CH4+ 2H2O Reaction 5Both reactions are exothermic and have standard enthalpies of reaction of about -206 kJ / mol and about -164 kJ / mol, respectively. Since the methanation reaction is exothermic, the reactionvessel for conducting the methanation reaction may include a heat exchange apparatus for removal of heat therefrom. In one example, the excess heat generated during the methanation reaction may be provided (e.g., as steam) to the electrolysis unit to promote the electrolysis reaction therein.

[0026] A solvent may optionally be used in combination with a catalyst for promoting methanation. Suitable solvents may bind carbon dioxide and / or carbon monoxide and facilitate the methanation reaction upon the catalyst. Suitable solvents may, for example, bind carbon dioxide and / or carbon monoxide through an amine moiety. Examples of solvents suitable for use in conjunction with methanation include, but are not limited to, N-(2-ethoxyethyl)-3- morpholinopropan-1 -amine (2-EEMPA), aminopyridine, monoethanolamine (ME A), the like, or any combination thereof.

[0027] Oxidative coupling of methane may occur under oxidative coupling conditions in an oxidative coupling unit to produce an olefinic product, water, and optionally, carbon dioxide. Any suitable reaction vessel may be used to conduct an oxidative coupling reaction in accordance with the present disclosure. Oxidative coupling of methane may be promoted using a suitable catalyst. Examples of suitable catalysts may include but are not limited to iron oxides, V2O5, MoOs, CO3O4, Pt — Rh, Li / ZrO2, Ag — Au, AU / CO3O4, Co / Mn, CeO2, MgO, La2O3, MmCM, Na2WO4, MnO, ZnO, and the like. In one example, the catalyst may be a supported catalyst such as Mn-Ce-Na2WO4 / SiO2, such as those developed by Siluria. Additional details regarding suitable catalysts and oxidative coupling reaction conditions may be found in U.S. Patents 8,921,256, 8,962,517, 9,718,054, 9,956,544, 10,793,490, 10,836,689, and 11,000835, and U.S. Patent Application Publications 2013 / 0158322, 2014 / 0121433, and 2014 / 0274671, each of which is incorporated herein by reference. The oxidative coupling reaction may occur at any suitable temperature and pressure conditions, such as a temperature of about 750°C to about 950°C and a pressure of about 5 atm to about 10 atm. The oxidative coupling reaction to produce ethylene is shown below in Reaction 6. The carbon dioxide byproduct resulting from the oxidative coupling reaction is not shown in Reaction 6.2CH4+ O2C2H4+ 2H2O Reaction 6The reaction is exothermic and has a standard enthalpy of reaction of about -280 kJ / mol. Since the oxidative coupling reaction is exothermic, the reaction vessel for conducting the oxidative coupling may include a heat exchange apparatus for removal of heat therefrom. In one example, the excess heat generated during the oxidative coupling reaction may be provided (e.g., as steam) to the electrolysis unit to promote the electrolysis reaction therein. Although Reaction 6 has shown an oxidative coupling reaction to produce ethylene, other olefinicproducts may be produced in varying amounts depending on reaction conditions. More generally, the olefinic product resulting from oxidative coupling may be a C2-C4 olefin, including any one or a combination of two or more of ethylene, propylene, butylene(s), or any combination thereof. Butylene(s) may include any combination of 1 -butene, 2-butene, and isobutylene.

[0028] As discussed above, methods of the present disclosure may incorporate heat exchange between the methanation unit and the electrolysis unit, between the oxidative coupling unit and the electrolysis unit, or any combination thereof. Such transfer of heat energy may promote direct or indirect heating of the electrolysis unit. Direct heating may occur by transferring heated water and / or steam from the methanation unit and / or the oxidative coupling unit to the interior of the electrolysis unit, such that the transferred heated water and / or steam itself undergoes the electrolysis reaction. Indirect heating may take place using a fluid line that may convey heated water and / or steam to the exterior of the electrolysis unit. Alternately, a heat transfer line may circulate a heat transfer fluid between the methanation unit and the electrolysis unit, between the oxidative cooling unit and the electrolysis unit, or any combination thereof to transfer thermal energy through any suitable indirect means. Suitable heat transfer fluids may include, but are not limited to, heat transfer oil, molten salts, water (e.g., steam), hydrocarbon fluids, or the like. Steam may be preferred for use as a heat transfer fluid according to the present disclosure.

[0029] Accordingly, in more specific examples, methods of the present disclosure may comprise: performing an electrolysis reaction of water to form hydrogen and oxygen, in which the electrolysis reaction or at least a portion of the water provided to the electrolysis reaction is heated; providing at least a portion of the hydrogen and carbon dioxide to a methanation unit; reacting the hydrogen and the carbon dioxide via a methanation reaction in the methanation unit to produce methane and water; providing at least a portion of the methane and at least a portion of the oxygen to an oxidative coupling unit; and reacting the methane and the oxygen via an oxidative coupling reaction in the oxidative coupling unit to produce an olefinic product, water, and optionally, additional carbon dioxide, in which the additional carbon dioxide, if produced, is also provided to the methanation unit as a second portion of carbon dioxide, and carbon dioxide obtained from an external source is provided to the methanation unit as a first portion of carbon dioxide.

[0030] It should be noted that additional nonlimiting components may be present in methods and systems of the present disclosure. Such additional components will be familiar to one having ordinary skill in the art and include, but are not limited to, valves, heat exchangers,conduits, gauges, sensors, compressors, controllers, the like, or any combination thereof. Conduits may be included in systems of the present disclosure for connecting units described herein and for fluidly conveying materials therebetween. As a nonlimiting example, various conduits may convey materials including hydrogen, oxygen, methane, and carbon dioxide between units of the present disclosure. A hydrogen conduit may be included in systems of the present disclosure for fluidly connecting an electrolysis unit and a methanation unit to flow hydrogen from the electrolysis unit to the methanation unit. An oxygen conduit may be included in systems of the present disclosure for fluidly connecting an electrolysis unit and an oxidative coupling unit to flow oxygen from the electrolysis unit to the oxidative coupling unit. A methane conduit may be included in systems of the present disclosure for fluidly connecting a methanation unit to an oxidative coupling unit to flow methane from the methanation unit to the oxidative coupling unit. A carbon dioxide conduit may be included in systems of the present disclosure for fluidly connecting an oxidative coupling unit to a methanation unit to flow carbon dioxide from the methanation unit to the oxidative coupling unit.

[0031] Accordingly, systems of the present disclosure may comprise: an electrolysis unit configured to flow an electric current through water to electrolyze the water and produce hydrogen and oxygen therefrom; a methanation unit configured to receive at least a portion of the hydrogen from the electrolysis unit and a first portion of carbon dioxide from an external source, and to react the hydrogen and the carbon dioxide via a methanation reaction to produce methane and water; an oxidative coupling unit configured to receive at least a portion of the oxygen from the electrolysis unit and at least a portion of the methane from the methanation unit, and to react the methane and the oxygen via an oxidative coupling reaction to produce an olefinic product, water, and optionally, an additional portion of carbon dioxide, in which the methanation unit is configured to receive the additional portion of carbon dioxide from the oxidative coupling unit; and a line configured to withdraw the olefinic product from the oxidative coupling unit. Preferably, the electrolysis unit may be configured to receive heated water and / or steam from the methanation unit and / or the oxidative coupling unit, such that the heated water and / or steam may also undergo the electrolysis reaction occurring in the electrolysis unit.Additional Embodiments

[0032] Embodiment 1. A method comprising: performing an electrolysis reaction of water to form hydrogen and oxygen; providing at least a portion of the hydrogen and carbon dioxide to a methanation unit; reacting the hydrogen and the carbon dioxide via a methanation reaction in the methanation unit to produce methane and water; providing at least a portion ofthe methane and at least a portion of the oxygen to an oxidative coupling unit; and reacting the methane and the oxygen via an oxidative coupling reaction in the oxidative coupling unit to produce an olefinic product, water, and optionally, additional carbon dioxide.

[0033] Embodiment !. The method of Embodiment 1, wherein the additional carbon dioxide is produced during the oxidative coupling reaction and is also provided to the methanation unit.

[0034] Embodiment 3. The method of Embodiment 2, wherein the carbon dioxide provided to the methanation unit comprises a first portion of carbon dioxide obtained from an external source and a second portion of carbon dioxide obtained from the additional carbon dioxide.

[0035] Embodiment 4. The method of Embodiment 2 or Embodiment 3, wherein all of the additional carbon dioxide is provided to the methanation unit.

[0036] Embodiment 5. The method of any one of Embodiments 1 -4, further comprising: heating the electrolysis reaction.

[0037] Embodiment 6. The method of any one of Embodiments 1-5, wherein the methanation reaction and the oxidative coupling reaction are both exothermic reactions, and heat from the exothermic reactions is provided to the electrolysis reaction as heated water.

[0038] Embodiment 7. The method of Embodiment 6, wherein the heated water is introduced to the electrolysis reaction.

[0039] Embodiment 8. The method of Embodiment 6 or Embodiment 7, wherein the heated water comprises a first portion of steam obtained from the methanation reaction and a second portion of steam obtained from the oxidative coupling reaction.

[0040] Embodiment 9. The method of any one of Embodiments 1-8, wherein the olefinic product comprises a C2-C4 alkene.

[0041] Embodiment 10. The method of any one of Embodiments 1-9, wherein the electrolysis reaction is driven by an electric current originating substantially from a lower- carbon generation source.

[0042] Embodiment 11. The method of any one of Embodiments 1-10, wherein a first portion of the oxygen is provided to the oxidative coupling unit, and a second portion of the oxygen is provided to an external location or is vented.

[0043] Embodiment 12. The method of Embodiment 1, wherein the electrolysis reaction is heated or at least a portion of the water provided to the electrolysis reaction is heated, a first portion of the carbon dioxide is provided to the methanation unit from an external source, andthe additional carbon dioxide is also provided to the methanation unit as a second portion of the carbon dioxide.

[0044] Embodiment 13. The method of Embodiment 12, wherein the methanation reaction and the oxidative coupling reaction are both exothermic reactions, and heat from the exothermic reactions is provided to the electrolysis reaction as heated water.

[0045] Embodiment 14. The method of Embodiment 13, wherein the heated water is introduced to the electrolysis reaction.

[0046] Embodiment 15. The method of Embodiment 13 or Embodiment 14, wherein the heated water comprises a first portion of steam obtained from the methanation reaction and a second portion of steam obtained from the oxidative coupling reaction.

[0047] Embodiment 16. The method of any one of Embodiments 1-15, wherein the olefinic product comprises a C2-C4 alkene.

[0048] Embodiment 17. A system comprising: an electrolysis unit configured to flow an electric current through water to electrolyze the water and produce hydrogen and oxygen therefrom; a methanation unit configured to receive at least a portion of the hydrogen from the electrolysis unit and a first portion of carbon dioxide from an external source, and to react the hydrogen and the carbon dioxide via a methanation reaction to produce methane and water; an oxidative coupling unit configured to receive at least a portion of the oxygen from the electrolysis unit and at least a portion of the methane from the methanation unit, and to react the methane and the oxygen via an oxidative coupling reaction to produce an olefinic product, water, and optionally, an additional portion of carbon dioxide; and a line configured to withdraw the olefinic product from the oxidative coupling unit.

[0049] Embodiment 18. The system of Embodiment 17, wherein the methanation unit is configured to receive the additional portion of carbon dioxide from the oxidative coupling unit.

[0050] Embodiment 19. The system of Embodiment 17 or Embodiment 18, wherein the electrolysis unit is configured to receive heated water from at least one of the methanation unit or the oxidative coupling unit.

[0051] Embodiment 20. The system of Embodiment 19, wherein the heated water comprises a first portion of steam obtained from the methanation unit and a second portion of steam obtained from the oxidative coupling unit.

[0052] All documents described herein are incorporated by reference herein for purposes of all jurisdictions where such practice is allowed, including any priority documents and / or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the disclosure havebeen illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the disclosure be limited thereby. For example, the compositions described herein may be free of any component, or composition not expressly recited or disclosed herein. Any method may lack any step not recited or disclosed herein. Likewise, the term “comprising” is considered synonymous with the term “including.” Whenever a method, composition, element or group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[0053] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by one or more embodiments described herein. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0054] Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0055] One or more illustrative embodiments are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment of the present disclosure, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and otherconstraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for one of ordinary skill in the art and having benefit of this disclosure.

[0056] Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to one having ordinary skill in the art and having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present disclosure. The embodiments illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and / or any optional element disclosed herein.

Claims

CLAIMSWhat is claimed is:

1. A method comprising: performing an electrolysis reaction of water to form hydrogen and oxygen; providing at least a portion of the hydrogen and carbon dioxide to a methanation unit; reacting the hydrogen and the carbon dioxide via a methanation reaction in the methanation unit to produce methane and water; providing at least a portion of the methane and at least a portion of the oxygen to an oxidative coupling unit; and reacting the methane and the oxygen via an oxidative coupling reaction in the oxidative coupling unit to produce an olefinic product, water, and optionally, additional carbon dioxide.

2. The method of claim 1, wherein the additional carbon dioxide is produced during the oxidative coupling reaction and is also provided to the methanation unit.

3. The method of claim 2, wherein the carbon dioxide provided to the methanation unit comprises a first portion of carbon dioxide obtained from an external source and a second portion of carbon dioxide obtained from the additional carbon dioxide.

4. The method of claim 2, wherein all of the additional carbon dioxide is provided to the methanation unit.

5. The method of claim 1, further comprising: heating the electrolysis reaction.

6. The method of claim 1, wherein the methanation reaction and the oxidative coupling reaction are both exothermic reactions, and heat from the exothermic reactions is provided to the electrolysis reaction as heated water.

7. The method of claim 6, wherein the heated water is introduced to the electrolysis reaction.

8. The method of claim 6, wherein the heated water comprises a first portion of steam obtained from the methanation reaction and a second portion of steam obtained from the oxidative coupling reaction.

9. The method of claim 1, wherein the olefinic product comprises a C2-C4 alkene.

10. The method of claim 1, wherein the electrolysis reaction is driven by an electric current originating substantially from a lower-carbon generation source.

11. The method of claim 1, wherein a first portion of the oxygen is provided to the oxidative coupling unit, and a second portion of the oxygen is provided to an external location or is vented.

12. The method of claim 1, wherein the electrolysis reaction is heated or at least a portion of the water provided to the electrolysis reaction is heated, a first portion of the carbon dioxide is provided to the methanation unit from an external source, and the additional carbon dioxide is also provided to the methanation unit as a second portion of the carbon dioxide.

13. The method of claim 12, wherein the methanation reaction and the oxidative coupling reaction are both exothermic reactions, and heat from the exothermic reactions is provided to the electrolysis reaction as heated water.

14. The method of claim 13, wherein the heated water is introduced to the electrolysis reaction.

15. The method of claim 13, wherein the heated water comprises a first portion of steam obtained from the methanation reaction and a second portion of steam obtained from the oxidative coupling reaction.

16. The method of claim 1, wherein the olefinic product comprises a C2-C4 alkene.

17. A system comprising: an electrolysis unit configured to flow an electric current through water to electrolyze the water and produce hydrogen and oxygen therefrom; a methanation unit configured to receive at least a portion of the hydrogen from the electrolysis unit and a first portion of carbon dioxide from an external source, and to react the hydrogen and the carbon dioxide via a methanation reaction to produce methane and water; an oxidative coupling unit configured to receive at least a portion of the oxygen from the electrolysis unit and at least a portion of the methane from the methanation unit, and to react the methane and the oxygen via an oxidative coupling reaction to produce an olefinic product, water, and optionally, an additional portion of carbon dioxide; and a line configured to withdraw the olefinic product from the oxidative coupling unit.

18. The system of claim 17, wherein the methanation unit is configured to receive the additional portion of carbon dioxide from the oxidative coupling unit.

19. The system of claim 17, wherein the electrolysis unit is configured to receive heated water from at least one of the methanation unit or the oxidative coupling unit.

20. The system of claim 19, wherein the heated water comprises a first portion of steam obtained from the methanation unit and a second portion of steam obtained from the oxidative coupling unit.

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