US20250154668A1

US20250154668A1 - Methods for producing hydrocarbons, and related electrochemical cells and systems

Info

Publication number: US20250154668A1
Application number: US18/946,797
Authority: US
Inventors: Lucun WANG; Dong Ding; Min Wang; Yingchao Yang
Original assignee: University of Maine System; Battelle Energy Alliance LLC
Current assignee: University of Maine System; Battelle Energy Alliance LLC
Priority date: 2023-11-14
Filing date: 2024-11-13
Publication date: 2025-05-15

Abstract

A method of forming at least one hydrocarbon from carbon dioxide comprises introducing steam to a first electrode of an electrochemical cell, and introducing carbon dioxide to a second electrode of the electrochemical cell. The electrochemical cell includes the first electrode, the second electrode, and an electrolyte between the first electrode and the second electrode. The second electrode comprises at least one catalyst material formulated to accelerate a carbon dioxide hydrogenation reaction to produce the at least one hydrocarbon product from the carbon dioxide. The method further comprises applying a potential difference between the first electrode and the second electrode of the electrochemical cell. Also disclosed are the electrochemical cell, and the system for producing one or more hydrocarbon product from carbon dioxide.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119 (e⁻) of U.S. Provisional Patent Application Ser. No. 63/598,817, filed Nov. 14, 2023, the disclosure of which is hereby incorporated herein in its entirety by this reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Contract Number DE-AC07-05-ID14517 awarded by the United States Department of Energy. The government has certain rights in the invention.

TECHNICAL FIELD

The disclosure, in various embodiments, relates to methods and systems for producing hydrocarbons (e.g., alkanes, olefins) through water oxidation and carbon dioxide (CO₂) reduction reactions (e.g., CO₂hydrogenation reactions), and to associated electrochemical cells.

BACKGROUND

Excessive emissions of carbon dioxide (CO₂) from sources such as fossil fuel power plants, oil refineries, industrial process plants, and other heavy industrial sources have led to a record-high concentration of carbon dioxide in the atmosphere. To mitigate the harmful impact of CO₂emissions, utilizing carbon dioxide as a feed stock for chemical or biological conversion into alternative materials has received increasing attention in recent years, particularly as a potential driver to develop carbon capture and storage (CCS).
Among various potential pathways, CO₂reduction or hydrogenation to synthesize valuable chemicals and fuels, such as methanol and olefins, has been considered an attractive and potentially viable approach for CO₂valorization and utilization. In particular, synthesis of light olefins from (CO₂) is of high interest to the chemical industry, since ethylene, propylene, and butylene are major building blocks in manufacturing polymers, chemical intermediates, and solvents. Currently, olefins (e.g., light olefins) are mainly produced by steam cracking of fossil-based feedstocks including naphtha and natural gases, which is known to be highly energy intensive and responsible for CO₂emissions. In addition, conventional steam cracking processes can require the use of complicated and costly systems and methods to purify (e.g., refine) the resulting olefin product.

BRIEF SUMMARY

In the first aspect of the disclosure, a method of forming at least one hydrocarbon from carbon dioxide comprises introducing steam to a first electrode of an electrochemical cell and introducing carbon dioxide to a second electrode of the electrochemical cell. The electrochemical cell includes the first electrode, the second electrode, and an electrolyte between the first electrode and the second electrode. The second electrode comprises at least one catalyst material formulated to accelerate a carbon dioxide hydrogenation reaction to produce the at least one hydrocarbon product from the carbon dioxide. The method further comprises applying a potential difference between the first electrode and the second electrode of the electrochemical cell.
In the second aspect of the disclosure, an electrochemical cell comprises a first electrode formulated to facilitate an oxidation reaction of water to produce oxygen, a second electrode formulated to facilitate a reduction reaction of carbon dioxide to produce at least one hydrocarbon, and an electrolyte between the first electrode and the second electrode. The second electrode comprises at least one catalyst material formulated to accelerate the reduction reaction of the carbon dioxide.
In the third aspect of the disclosure, a system for producing one or more hydrocarbon from carbon dioxide comprises an electrochemical apparatus in fluid communication with a first vessel configured to contain steam and a second vessel configured to contain carbon dioxide. The electrochemical apparatus includes a housing structure and electrochemical cells within the housing structure. The housing structure is configured and positioned to receive a steam stream from the first vessel and to receive a carbon dioxide stream from the second vessel. One or more of the electrochemical cells individually comprises a first electrode, a second electrode, and an electrolyte between the first electrode and the second electrode. The second electrode comprises at least one catalyst material formulated to accelerate a carbon dioxide hydrogenation reaction to produce the at least one hydrocarbon from the carbon dioxide. The at least one catalyst material includes a perovskite-based material containing iron (Fe) and one or more of zinc (Zn), zirconium (Zr), cerium (Ce), cobalt (Co), copper (Cu), manganese (Mn), and indium (In).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic view of a system for producing hydrocarbon compounds, in accordance with embodiments of the disclosure;

FIG. 2 is a simplified cross-sectional view of an electrochemical cell for producing hydrocarbon compounds, in accordance with additional embodiments of the disclosure;

FIG. 3 is a simplified cross-sectional view of an electrochemical cell for producing ethylene, in accordance with additional embodiments of the disclosure;

FIG. 4 is a simplified schematic view of a system for producing hydrocarbon compounds, in accordance with additional embodiments of the disclosure;

FIG. 5A is a graphical comparison of CO₂conversion associated with Fe-based catalysts, as described in Example 2;

FIG. 5B is a graphical comparison of CO and hydrocarbon selectivity associated with Fe-based catalysts, as described in Example 2;

FIG. 6A is a graphical comparison of product selectivity and CO₂conversion associated with a FeZnZr/K catalyst at varying reaction temperatures, as described in Example 3;

FIG. 6B is a graphical comparison of product selectivity and CO₂conversion associated with a FeZnZr/K catalyst at varying reaction pressures, as described in Example 3;

FIG. 6C is a graphical comparison of product selectivity and CO₂conversion associated with a FeZnZr/K catalyst and varying H₂/CO₂ratios, as described in Example 3;

FIG. 6D is a graphical comparison of product selectivity and CO₂conversion associated with a FeZnZr/K catalyst and varying space velocities of a feed gas, as described in Example 3;

FIG. 7A is a graphical comparison of product selectivity and CO₂conversion of a protonic ceramic electrochemical cell (PCEC) including a FeZnZr/K catalyst at varying applied current, as described in Example 6;

FIG. 7B is a graphical comparison of hydrocarbon product selectivity and voltage of a PCEC including a FeZnZr/K catalyst at varying applied current, as described in Example 6;

FIG. 8A is a graphical representation showing current density results (e.g., polarization curves) and power density results of a PCEC including a BFZZY catalyst operated as an electrolysis cell, as described in Example 7;

FIG. 8B is a graphical representation of results associated with electron impedance spectroscopy (EIS) measurements, as described in Example 7;

FIG. 8C is a graphical representation showing current density results (e.g., polarization curves) and power density results of a PCEC including a BFZZY catalyst operated as an electrolysis cell, as described in Example 7; and

FIG. 8D is a graphical representation of results associated with EIS measurements, as described in Example 7.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which are shown, by way of illustration, specific example embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable a person of ordinary skill in the art to practice the disclosure. However, other embodiments may be utilized, and structural, material, and process changes may be made without departing from the scope of the disclosure.
The detailed description provides specific details, such as material compositions and processing conditions (e.g., temperatures, pressures, flow rates, etc.) in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without necessarily employing these specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional systems and methods employed in the industry. In addition, only those process components and acts necessary to understand the embodiments of the disclosure are described in detail below. A person of ordinary skill in the art will understand that some process components (e.g., pipelines, line filters, valves, temperature detectors, flow detectors, pressure detectors, and the like) are inherently disclosed herein and that adding various conventional process components and acts would be in accord with the disclosure. In addition, the drawings accompanying the application are for illustrative purposes only, and are not meant to be actual views of any particular material, device, or system.
It will be readily understood that the components of the embodiments as described herein and illustrated in the drawings may be arranged and designed in a wide variety of different configurations. Thus, the following description of various embodiments is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments may be presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
As used herein, the singular forms following “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
As used herein, “and/or” includes any and all combinations of one or more of the associated listed items.
As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,” “right,” and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures. For example, if materials in the figures are inverted, elements described as “below” or “beneath” or “under” or “on bottom of” other elements or features would then be oriented “above” or “on top of” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below, depending on the context in which the term is used, which will be evident to one of ordinary skill in the art. The materials may be otherwise oriented (e.g., rotated 90 degrees, inverted, flipped) and the spatially relative descriptors used herein interpreted accordingly.
As used herein, the term “configured” refers to a size, shape, material composition, material distribution, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a pre-determined way.
As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, at least 99.9% met, or even 100.0% met.
As used herein, the term “about” used in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter, as well as variations resulting from manufacturing tolerances, etc.). In some embodiments, the term “about” refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of from 9% to 11%, and “about 1” may mean from 0.9 to 1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5 to 1.4.
In general, the amount of a compound in a composition as disclosed herein is expressed “by weight” which refers to a percentage of the compound's weight in a total weight of the composition. Unless indicated otherwise, all concentrations are expressed as weight percentage concentrations.
As used herein, the term “comprise(s).” “comprising,” “include(s),” “including,” “having,” “has,” “contain(s),” “containing,” and variants thereof, are open-ended transitional phrases, terms, or words that are meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
As used herein, the terms “catalyst material” and “catalyst” each mean and include a material formulated to promote one or more reactions, resulting in the formation of a product.
As used herein, the term “negative electrode” means and includes an electrode having a relatively lower electrode potential in an electrochemical cell (i.e., lower than the electrode potential in a positive electrode therein). Conversely, as used herein, the term “positive electrode” means and includes an electrode having a relatively higher electrode potential in an electrochemical cell (i.e., higher than the electrode potential in a negative electrode therein). Whether an electrode in the electrochemical cell is positive or negative may depend on an electrical potential being applied to the electrochemical cell. For instance, if the potential is reversed, the polarity of the electrodes will be reversed as well.
As used herein the term “electrolyte” means and includes an ionic conductor, which may be in a solid state, a liquid state, or a gas state (e.g., plasma).
As used herein, the term “compatible” means that a material does not undesirably react, decompose, or absorb another material, and also that the material does not undesirably impair the chemical and/or mechanical properties of the another material.
As used herein, the term “hydrocarbon compound” means and includes an organic compound consisting entirely of hydrogen atoms and carbon atoms.
As used herein, the term “alkane” means and includes saturated hydrocarbon compound consisting of carbon atoms and hydrogen atoms bonded together by at least one single carbon-carbon bond and at least one carbon-hydrogen bond. Non-limiting examples of alkanes include methane (CH₄), ethane (C₂H₆), propane (C₃H₈), octane (a major component of gasoline, C₈H₁₈).
As used herein, the term “olefin” means and includes an unsaturated hydrocarbon compound containing at least one carbon-carbon double bond.
As used herein, the term “light olefin” means and includes ethylene (C₂H₄), propylene (C₃H₆), butylene (C₄H₈), or a combination thereof.
As used herein, the term “steam” means and includes water vapor (i.e., water in its gaseous state).
Methods and systems for producing hydrocarbons (e.g., alkanes, olefins such as light olefins) through carbon dioxide reduction reactions (e.g., CO₂hydrogenation reactions) are disclosed.
In some embodiments, a method of producing one or more hydrocarbons from carbon dioxide includes introducing (e.g., delivering) steam (e.g., gaseous H₂O) and carbon dioxide to an electrochemical apparatus including at least one electrochemical cell therein. In some of such embodiments, the one or more hydrocarbons includes olefins. In some of such embodiments, the one or more hydrocarbons includes light olefins, e.g., ethylene, propylene, butylene.
The electrochemical cell includes a first electrode (e.g., a positive electrode, an anode), a second electrode (e.g., a negative electrode, a cathode), and an electrolyte (e.g., a proton-conducting membrane) between the positive electrode and the negative electrode. The positive electrode is formulated to facilitate production of hydrogen ions (H⁺), oxygen (O₂), and electrons (e⁻) from the steam. The negative electrode is formulated to facilitate production of hydrocarbons (e.g., olefins such as light olefins, alkanes) from CO₂and the produced H⁺ and e⁻. The negative electrode includes at least one catalyst material formulated to accelerate production of the olefins from the CO₂and the produced H⁺ and e⁻.
In some embodiments, the negative electrode includes at least one catalyst material exhibiting a relatively high selectivity (e.g., greater than about 40%) for the formation of one or more hydrocarbons (e.g., alkanes, olefins such as light olefins) relative to carbon monoxide. In some embodiments, the negative electrode includes at least an Fe-based catalyst material.
The electrolyte may be formulated to exhibit an ionic conductivity greater than or equal to about 10⁻²S/cm at one or more temperatures within a range of from about 350° C. to about 650° C. The steam is introduced to the positive electrode of the electrochemical cell, the carbon dioxide (CO₂) is introduced to the negative electrode of the electrochemical cell, and a potential difference is applied between the positive electrode and the negative electrode of the electrochemical cell to produce the hydrocarbons. The methods, systems, and apparatuses of the disclosure may be more efficient (e.g., increasing olefin production efficiencies; reducing equipment, material, and/or energy requirements), less complicated, and result in a significant reduction in carbon emissions compared to conventional methods, conventional systems, and conventional apparatuses for producing hydrocarbons.
FIG. 1 illustrates a simplified schematic view of a system 100 for producing hydrocarbon compounds (e.g., alkanes, olefins such as light olefins) from carbon dioxide according to embodiments of the disclosure. The system 100 may be used to convert carbon dioxide and hydrogen into at least one hydrocarbon compound (e.g., ethylene, propylene, butylene, octane, or a combination thereof). In some embodiments, the system 100 is used to convert carbon dioxide and hydrogen into at least one light olefin (e.g., ethylene, propylene, butylene).
As shown in FIG. 1 , the system 100 may include at least one steam source 102 (e.g., a containment vessel, a steam generator), at least one carbon dioxide source 104 (e.g., a containment vessel), and at least one electrochemical apparatus 106 in fluid communication with each of the steam source 102 and the carbon dioxide source 104. The electrochemical apparatus 106 includes a housing structure 108, and at least one electrochemical cell 110 contained within the housing structure 108. The electrochemical cell 110 is electrically connected (e.g., coupled) to a power source 118, and includes a positive electrode 112 (e.g., an anode), a negative electrode 116 (e.g., a cathode), and an electrolyte 114 (e.g., a proton-conducting electrolyte, a proton-conducting membrane) between the positive electrode 112 and the negative electrode 116.
The power source 118 may provide clean (e.g., carbon-free) electricity (e.g., electricity that is generated without direct emissions of greenhouse gases, such as carbon dioxide, during the generating process).
The system 100 may be configured as a protonic ceramic electrochemical membrane reactor (PC-EMR). In some embodiments, the electrochemical cell 110 is a protonic ceramic electrochemical cell (PCEC).
The electrochemical cell 110 may operate as an electrolysis cell to convert the carbon dioxide into the one or more hydrocarbon compounds. The electrochemical cell 110 may operate in reverse as a fuel cell to generate electricity from one or more hydrocarbon compounds (e.g., at least a portion of the one or more hydrocarbon products produced when the electrochemical cell 110 is operated as an electrolysis cell). As shown in FIG. 1 , optionally, the system 100 may also include at least one heating apparatus 120 operatively associated with the electrochemical apparatus 106. The heating apparatus 120 may generate heat via a clean (e.g., carbon-free) process (e.g., a process that generates heat without direct emissions of greenhouse gases, such as carbon dioxide, during the process). The system 100 may include a vacuum pump (not shown) in operative communication with the housing structure 108.
During use and operation, the system 100 directs a steam stream 122 from the steam source 102 into the electrochemical apparatus 106 to interact with the positive electrode 112 of the electrochemical cell 110. The steam stream 122 functions as a source of hydrogen. A potential difference (e.g., a voltage) is applied between the positive electrode 112 and the negative electrode 116 of the electrochemical cell 110 by the power source 118 so that as the steam interacts with the positive electrode 112, H atoms of the H₂O release their electrons (e⁻) to generate oxygen gas (O₂), hydrogen ions (H⁺) (e.g., protons), and electrons (e⁻) via a water oxidation reaction, according to the following equation:
2H₂O→4H⁺+O₂+4e ⁻ (1).
The generated H⁺ ions permeate (e.g., diffuse) across the electrolyte 114 to the negative electrode 116. A flux of H⁺ ions across the electrolyte 114 may be controlled by the potential difference applied between the positive electrode 112 and the negative electrode 116. Since the generated H⁺ ions are an ionized (e.g., activated) form of hydrogen, lower activation energy is needed during the CO₂hydrogenation reaction, resulting in faster reaction kinetics compared to thermal catalytic CO₂hydrogenation reactions. The generated electrons are directed to the power source 118 through external circuitry (not shown). The electrons generated at the positive electrode 112 may, for example, flow from the positive electrode 112 through the power source 118 and into the negative electrode 116. At the negative electrode 116, the generated H⁺ ions exiting the electrolyte 114 react with carbon dioxide and the electrons received from the power source, in the presence of a catalyst material of the negative electrode 116, to produce at least one hydrocarbon compound via a CO₂reduction reaction (e.g., a CO₂hydrogenation reaction). The carbon dioxide may be introduced into the electrochemical apparatus 106 as a carbon dioxide stream 124 from the carbon dioxide source 104. For example, the generated H⁺ ions exiting the electrolyte 114 may react with carbon dioxide and electrons in the presence of the catalyst material of the negative electrode 116 to produce ethylene (C₂H₄), according to the following equation:
2CO₂+12H⁺+12e ⁻→C₂H₄+4H₂O (2).
One or more byproducts, such as carbon monoxide (CO) and methane (CH₄), may also be produced at the negative electrode 116. The produced hydrocarbon compounds, H₂O, and byproducts (if present) exit the electrochemical apparatus as hydrocarbon product stream 126. In some embodiments, the byproducts (if present), H₂O, and unreacted carbon dioxide in the hydrocarbon product stream 126 are separated from the hydrocarbon product stream 126. At the positive electrode 112, the generated oxygen and unreacted H₂O (if present) may exit the electrochemical apparatus as oxygen stream 128.
As described in further detail below, the production of H⁺ ions, oxygen, and electrons at the positive electrode 112, as well as the production of one or more hydrocarbon compounds (e.g., alkanes, olefins such as light olefins) at the negative electrode 116 may at least partially depend on the material compositions and flow rates of the steam stream 122 and the carbon dioxide stream 124; the configuration (e.g., size, shape, material composition, material distribution, arrangement) of the positive electrode 112, including the types, quantities, distribution, and properties (e.g., geometric properties, thermodynamic properties, etc.) of catalyst materials thereof promoting water oxidation reactions; the configuration of the electrolyte 114, and the impact thereof on the diffusivity (e.g., diffusion rate) of generated H⁺ ions therethrough; the configuration of the negative electrode 116, including the types, quantities, and properties (e.g., geometric properties, thermodynamic properties, etc.) of catalyst materials thereof; and the operational parameters (e.g., temperatures, pressures, etc.) of the electrochemical apparatus 106. Such operational factors may be controlled (e.g., adjusted, maintained, etc.) as desired to control the quantities and rate of production of the H⁺ ions, oxygen, and electrons produced at the positive electrode 112 and to control the quantity and rate of production of the one or more hydrocarbon compounds produced at the negative electrode 116. By way of example only, relative amounts of the components of the hydrocarbon product stream 126 may be tailored by adjusting the applied current or potential applied between the positive electrode 112 and the negative electrode 116.
The steam source 102 may include at least one apparatus configured and operated to produce the steam stream 122 including steam.
When the electrochemical cell 110 is operated as a fuel cell, the steam source 102 may receive a H₂O recycle stream (not shown) containing one or more phases of H₂O exiting the electrochemical apparatus 106. By way of non-limiting example, the steam source 102 may comprise a boiler apparatus configured and operated to heat liquid H₂O to a temperature greater than or equal to about 100° C. to produce steam. In some embodiments, the steam source 102 is configured and operated to convert the liquid H₂O to steam H₂O having a temperature within a range of an operating temperature of the electrochemical cell 110 of the electrochemical apparatus 106, such as a temperature within a range of from about 150° C. to about 650° C. In some embodiments, the steam source 102 is configured and operated to convert the liquid H₂O into steam having a temperature below the operating temperature of the electrochemical cell 110. In such embodiments, the heating apparatus 120 may be employed to further heat the steam stream 122 to the operational temperature of the electrochemical cell 110, as described in further detail below.
The steam stream 122 may be formed of and include gaseous H₂O. The steam stream 122 may, optionally, include one or more other materials (e.g., molecules), such as one or more of nitrogen (N₂), argon (Ar), carbon dioxide (CO₂), and oxygen (O₂). In some embodiments, the steam stream 122 is at least substantially free of materials other than H₂O. The steam stream 122 may be substantially gaseous (e.g., may only include a single gaseous phase) or may include a combination of gaseous and liquid phases. In some embodiments, the steam stream 122 is at least substantially gaseous. One or more apparatuses (e.g., heat exchangers, pumps, compressors, expanders, mass flow control devices, etc.) may be employed within the system 100 to adjust the one or more of the temperature, pressure, and flow rate of the steam stream 122 delivered into the electrochemical apparatus 106.
A single (e.g., only one) steam stream 122 may be directed into the electrochemical apparatus 106 from the steam source 102, or multiple (e.g., more than one) steam streams 122 may be directed into the electrochemical apparatus 106 from the steam source 102. If multiple steam streams 122 are directed into the electrochemical apparatus 106, each of the multiple steam streams 122 may exhibit at least substantially the same properties (e.g., at least substantially the same material composition, at least substantially the same temperature, at least substantially the same pressure, at least substantially the same flow rate, etc.), or at least one of the multiple steam streams 122 may exhibit one or more different properties (e.g., a different material composition, a different temperature, a different pressure, a different flow rate, etc.) than at least one other of the multiple steam streams 122.
While a steam source 102 and steam stream 122 are described in detail herein, the system 100 may include one or more of a light alkane (e.g., methane, ethane, propane, etc.) source, an ammonia source, and any other suitable hydrogen source as an alternative or in addition to the steam source 102. Similarly, the system 100 may include one or more of a light alkane (e.g., methane, ethane, propane, etc.) stream, an ammonia stream, and a stream including any other suitable reactant to generate H⁺ ions and electrons at the positive electrode 112 as an alternative or in addition to the steam stream 122.
The carbon dioxide stream 124 entering the electrochemical apparatus 106 may be formed of and include carbon dioxide. The carbon dioxide may be present in the carbon dioxide stream 124 in one or more of a gaseous phase and a liquid phase. The phase(s) of the carbon dioxide (and, hence, a temperature and a pressure of the carbon dioxide stream 124) may at least partially depend on the operating temperature of the electrochemical cell 110 of the electrochemical apparatus 106. For example, at operating temperatures less than or equal to about 250° C. (e.g., within a range of from about 150° C. to about 250° C.), the carbon dioxide may be present in the carbon dioxide stream 124 in a liquid phase (e.g., carbon dioxide dissolved in an ionic liquid), a gaseous phase, or a combination thereof. At operating temperatures greater than about 250° C. (e.g., within a range of about 250° C. to about 650° C.), the carbon dioxide may be present in the carbon dioxide stream 124 in a gaseous phase. The carbon dioxide stream 124 may only include carbon dioxide (e.g., about 100% CO₂), or may include carbon dioxide and one or more other materials. In some embodiments, the carbon dioxide stream 124 is substantially free of materials other than carbon dioxide. One or more apparatuses (e.g., heat exchangers, pumps, compressors, expanders, mass flow control devices, etc.) may be employed within the system 100 to adjust one or more of the temperature, pressure, and flow rate of the carbon dioxide stream 124 delivered into the electrochemical apparatus 106.
A single (e.g., only one) carbon dioxide stream 124 may be directed into the electrochemical apparatus 106, or multiple (e.g., more than one) carbon dioxide streams 124 may be directed into the electrochemical apparatus 106. If multiple carbon dioxide streams 124 are directed into the electrochemical apparatus 106, each of the multiple carbon dioxide streams 124 may exhibit at least substantially the same properties (e.g., at least substantially the same material composition, at least substantially the same temperature, at least substantially the same pressure, at least substantially the same flow rate, etc.), or at least one of the multiple carbon dioxide streams 124 may exhibit one or more different properties (e.g., a different material composition, a different temperature, a different pressure, a different flow rate, etc.) than at least one other of the multiple carbon dioxide streams 124. In some embodiments, at least one of the multiple carbon dioxide streams 124 is a recycled carbon dioxide stream (not shown) containing one or more phases of unreacted carbon dioxide and, optionally, one or more other materials, such as carbon monoxide (CO), separated from the hydrocarbon product stream 126 exiting the electrochemical apparatus 106.
The heating apparatus 120, if present, may comprise at least one apparatus (e.g., one or more of a combustion heater, an electrical resistance heater, an inductive heater, and an electromagnetic heater) configured and operated to heat one or more of the steam stream 122, the carbon dioxide stream 124, and at least a portion of the electrochemical apparatus 106 to an operating temperature of the electrochemical apparatus 106. The operating temperature of the electrochemical apparatus 106 may at least partially depend on a material composition of the electrolyte 114 of the electrochemical cell 110, as described in further detail below. In some embodiments, the heating apparatus 120 heats one or more of the steam stream 122, the carbon dioxide stream 124, and at least a portion of the electrochemical apparatus 106 to a temperature within a range of from about 150° C. to about 650° C. In additional embodiments, such as in embodiments where a temperature of one or more of the steam stream 122 and the carbon dioxide stream 124 is already within the operating temperature range of the electrochemical cell 110 of the electrochemical apparatus 106, the heating apparatus 120 may be omitted (e.g., absent) from the system 100.
The vacuum pump (not shown), if present, may comprise at least one apparatus configured and operated to generate and maintain an operating pressure of one or more of the steam stream 122, the carbon dioxide stream 124, and at least a portion of the electrochemical apparatus 106. The operating pressure of the electrochemical apparatus 106 may at least partially depend on a material composition of the electrolyte 114 of the electrochemical cell 110, as described in further detail below. In some embodiments, the operating pressure of the electrochemical apparatus 106 is within a range of from about 1 bar to about 6 bar. In additional embodiments, such as in embodiments where a pressure of one or more of the steam stream 122, the carbon dioxide stream 124, and the electrochemical apparatus 106 is already within the operating pressure range of the electrochemical cell 110 of the electrochemical apparatus 106, the vacuum pump may be omitted (e.g., absent) from the system 100.
With continued reference to FIG. 1 , the electrochemical apparatus 106, including the housing structure 108 and the electrochemical cell 110 thereof, is configured and operated to form the hydrocarbon product stream 126 and the oxygen stream 128 from the steam stream 122 and the carbon dioxide stream 124 according to the reaction of Equation (1) above and at least one CO₂reduction reaction, such as the reaction of Equation (2) above. The housing structure 108 may exhibit any shape (e.g., a tubular shape, a quadrilateral shape, a spherical shape, a semi-spherical shape, a cylindrical shape, a semi-cylindrical shape, truncated versions thereof, or an irregular shape) and size able to contain (e.g., hold) the electrochemical cell 110 therein, to receive and direct the steam stream 122 to the positive electrode 112 of the electrochemical cell 110, to direct oxygen (O₂) formed at the positive electrode 112 away from the electrochemical apparatus 106 as the O₂stream 128, and to direct the hydrocarbon compounds (e.g., ethylene, propylene, butylene) formed at the negative electrode 116 of the electrochemical cell 110 away from the electrochemical apparatus 106 as the hydrocarbon product stream 126. In addition, the housing structure 108 may be formed of and include any material (e.g., glass, metal, alloy, polymer, ceramic, composite, combination thereof, etc.) compatible with the operating conditions (e.g., temperatures, pressures, etc.) of the electrochemical apparatus 106.
The housing structure 108 may at least partially define at least one internal chamber 130 at least partially surrounding the electrochemical cell 110. The electrochemical cell 110 may serve as a boundary between a first region 132 (e.g., an anodic region) of the internal chamber 130 configured and positioned to receive the steam stream 122 and to direct the O₂stream 128 from the electrochemical apparatus 106, and a second region 134 (e.g., a cathodic region) of the internal chamber 130 configured and positioned to receive the one or more hydrocarbon compounds produced at the negative electrode 116 of the electrochemical cell 110. Molecules (e.g., H₂O) of the steam stream 122 may be substantially limited to the first region 132 of the internal chamber 130 by the configurations and positions of the housing structure 108 and the electrochemical cell 110. Keeping the second region 134 of the internal chamber 130 substantially free of molecules from the steam stream 122 circumvents additional processing of the produced hydrocarbon compounds (e.g., to separate the produced hydrocarbon compounds from H₂O and/or O₂) that may otherwise be necessary if the components of the steam stream 122 were also delivered to within the second region 134 of the internal chamber 130.
As shown in FIG. 1 , the positive electrode 112 and the negative electrode 116 of the electrochemical cell 110 are electrically coupled to the power source 118, and the electrolyte 114 is disposed on and between the positive electrode 112 and the negative electrode 116. The electrolyte 114 is configured and formulated to conduct H⁺ ions from the positive electrode 112 to the negative electrode 116, while electrically insulating the negative electrode 116 from the positive electrode 112. Electrons generated at the positive electrode 112 through the reaction of Equation (1) described above may, for example, flow from the positive electrode 112 into a negative current collector, through the power source 118 and a positive electrode current collector, and into negative electrode 116 to facilitate the synthesis of CO₂hydrogenation products at the negative electrode 116.
The electrochemical cell 110 may operate at an operational temperature within a range of from about 150° C. to about 650° C., such as from about 200° C. to about 600° C., from about 250° C. to about 550° C., from about 300° C. to about 500° C., or from about 350° C. to about 450° C. In some embodiments, the electrochemical cell 110 operates at an operational temperature within a range of from about 300° C. to about 500° C. The electrochemical cell 110 may operate at an operational pressure within a range of from about 1 bar to about 20 bar, such as from about 1 bar to about 4 bar, from about 1 bar to about 10 bar, from about 5 bar to about 10 bar, or from about 5 bar to about 20 bar. The electrochemical cell 110 may operate at current densities greater than or equal to about 0.1 amperes per square centimeter (A/cm²), such as greater than or equal to about 0.5 A/cm², greater than or equal to about 1.0 A/cm², or greater than or equal to about 2.0 A/cm². In some embodiments, the electrochemical cell may operate at current densities within a range of from about 0.1 A/cm²to about 3.0 A/cm², such as within a range of from about 1.0 A/cm²to about 2.0 A/cm².
The electrolyte 114 may be a proton-conducting membrane. The electrolyte 114 may be formed of and include at least one electrolyte material exhibiting an ionic conductivity (e.g., H⁺ conductivity) greater than or equal to about 10⁻²S/cm, such as within a range of from about 10⁻²S/cm to about 1 S/cm, at one or more temperatures within a range of from about 150° C. to about 650° C., such as from about 300° C. to about 500° C. The electrolyte material may be formulated to remain substantially adhered (e.g., laminated) to the positive electrode 112 and the negative electrode 116 at relatively high current densities, such as at current densities greater than or equal to about 0.1 A/cm²(e.g., greater than or equal to about 0.5 A/cm², greater than or equal to about 1.0 A/cm², greater than or equal to about 2.0 A/cm²). The electrolyte 114 may be formed of and include one or more of a perovskite material, a solid acid material, and a polybenzimidazole (PBI) material. The material composition of the electrolyte 114 may provide the electrolyte 114 with enhanced ionic conductivity at a temperature within a range of from about 150° C. to about 650° C. as compared to conventional membranes (e.g., membranes employing conventional electrolyte materials, such as yttria-stabilized zirconia (YSZ)) of conventional electrolysis cells.
In some embodiments, the electrolyte 114 is formed of and includes at least one perovskite material having an operational temperature (e.g., a temperature at which the conductivity of the perovskite material is greater than or equal to about 10⁻²S/cm, such as within a range of from about 10⁻²S/cm to about 1 S/cm) within a range of from about 350° C. to about 650° C. The electrolyte 114 may be formed of and include a perovskite material exhibiting a cubic lattice structure with a general formula ABO_3-δ, where A may comprise barium (Ba), B may comprise one or more of zirconium (Zr), cerium (Ce), yttrium (Y), and ytterbium (Yb), and 8 is the oxygen deficit. By way of non-limiting example, the electrolyte 114 may be formed of and include one or more of a yttrium- and ytterbium-doped barium-zirconate-cerate (BZCYYb), such as BaZr_0.8-yCe_yY_0.2-xYb_xO_3-δ, where x and y are dopant levels and δ is the oxygen deficit (e.g., BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb1711), BaZr_0.4Ce_0.4Y_0.1Yb_0.1O_3-δ (BZCYYb4411), BaZr_0.3Ce_0.5Y_0.1Yb_0.1O_3-δ (BZCYYb3511)), a yttrium- and ytterbium-doped barium-strontium-niobate (BSNYYb), a doped barium-cerate (BaCeO₃) (e.g., yttrium-doped BaCeO₃(BCY)) a doped barium-zirconate (BaZrO₃) (e.g., yttrium-doped BaZrO₃(BZY), such as BaZr_0.8Y_0.2O_3-δ where δ is the oxygen deficit), barium-yttrium-stannate (Ba₂(YSn)O_5.5), and barium-calcium-niobate (Ba₃(CaNb₂)O₉). In some embodiments, the electrolyte 114 is formed of and includes BZCYYb.
In further embodiments, the electrolyte 114 is formed of and includes at least one solid acid material having an operational temperature (e.g., a temperature at which the conductivity of the perovskite material is greater than or equal to about 10⁻²S/cm, such as within a range of from about 10⁻²S/cm to about 1 S/cm) within a range of from about 200° C. to about 400° C. By way of non-limiting example, the electrolyte 114 may include a solid acid phosphate material, such as solid acid cesium dihydrogen phosphate (CsH₂PO₄). The solid acid material may be doped (e.g., doped CsH₂PO₄), or may be undoped (e.g., undoped CsH₂PO₄). In some embodiments, the electrolyte 114 comprises CsH₂PO₄.
In additional embodiments, the electrolyte 114 is formed of and includes at least one polybenzimidazole (PBI) material having an operational temperature (e.g., a temperature at which the conductivity of the perovskite material is greater than or equal to about 10⁻²S/cm, such as within a range of from about 10⁻²S/cm to about 1 S/cm) within a range of from about 150° C. to about 250° C. By way of non-limiting example, the electrolyte 114 may comprise a doped PBI, such as phosphoric acid (H₃PO₄) doped PBI. In some embodiments, the electrolyte 114 comprises H₃PO₄-doped PBI.
The electrolyte 114 may be at least substantially homogeneous (e.g., exhibiting an at least substantially uniform material composition throughout the electrolyte 114) or may be at least substantially heterogeneous (e.g., exhibiting varying material composition throughout the electrolyte 114). In some embodiments, the electrolyte 114 is at least substantially homogeneous. In additional embodiments, the electrolyte 114 is at least substantially heterogeneous. The electrolyte 114 may, for example, include a stack of at least two (e.g., at least three, at least four, etc.) different electrolyte materials. As a non-limiting example, the electrolyte 114 may comprise a stack of at least two (e.g., at least three, at least four, etc.) different perovskite materials individually having an operational temperature within a range of from about 350° C. to about 650° C. As another non-limiting example, the electrolyte 114 may comprise a stack of at least two (e.g., at least three, at least four, etc.) different solid acid materials individually having an operational temperature within a range of from about 200° C. to about 400° C. As a further non-limiting example, the electrolyte 114 may comprise a stack of at least two (e.g., at least three, at least four, etc.) different PBI materials individually having an operational temperature within a range of from about 150° C. to about 250° C.
The electrolyte 114 may exhibit any desired dimensions (e.g., length, width, thickness) and any desired shape, such as one of a cubic shape, a cuboidal shape, a tubular shape, a tubular spiral shape, a spherical shape, a semi-spherical shape, a cylindrical shape, a semi-cylindrical shape, a conical shape, a triangular prismatic shape, a truncated version of one or more of the foregoing, or an irregular shape. The dimensions and shape of the electrolyte 114 may be selected such that the electrolyte 114 at least substantially intervenes between opposing surfaces of the positive electrode 112 and the negative electrode 116. A thickness of the electrolyte 114 may at least partially depend on the material composition and thickness of the positive electrode 112. In some embodiments, a thickness of the electrolyte 114 is at least about 100 microns (μm), such as, for example, at least about 150 μm, at least about 200 μm, or at least about 250 μm.
The positive electrode 112 and the negative electrode 116 may individually be formed of and include at least one material compatible with the material composition of the electrolyte 114 and the operating conditions (e.g., temperature, pressure, current density) of the electrochemical apparatus 106 and the electrochemical cell 110, and facilitating the formation of the hydrocarbon product stream 126 and the O₂stream 128 from the steam stream 122, as well as the CO₂stream 124, at an operational temperature within a range of from about 150° C. to about 650° C. Accordingly, the material compositions of the positive electrode 112 and the negative electrode 116 may be selected relative to one another, the material composition of the electrolyte 114, and the operating conditions (e.g., temperature, pressure, current density, etc.) of the electrochemical apparatus 106 and the electrochemical cell 110.
The positive electrode 112 may be formed of and include a material compatible with the material of the electrolyte 114 and the material of the negative electrode 116 under the operating conditions (e.g., temperature, pressure, current density) of the electrochemical cell 110. The material composition of the positive electrode 112 may facilitate production of H⁺ ions, oxygen, and electrons from steam. As a non-limiting example, if the electrolyte 114 includes a perovskite material (e.g., a BZCYYb, a BSNYYb, a doped BaCeO₃, a doped BaZrO₃, Ba₂(YSn)O_5.5, Ba₃(CaNb₂)O₉), the positive electrode 112 may be formed of and include at least one perovskite material compatible with the perovskite material of the electrolyte 114. The positive electrode 112 may be formed of and include at least one perovskite material that accelerates (e.g., catalyzes) reaction rates (e.g., water oxidation reaction rates) at the positive electrode 112 to produce H⁺ ions, oxygen, and electrons from steam in accordance with Equation (1) above. By way of non-limiting example, the positive electrode 112 may be formed of and include one or more of a triple conducting perovskite material, such as Pr(Co_1-x-y-z, Ni_x, Mn_y, Fe_z)O_3-δ, where 0≤x≤0.9, 0≤y≤0.9, 0≤z≤0.9, and δ is an oxygen deficit (e.g., PrNi_0.5Co_0.5O_3-δ (PNC55)) or (Pr_1-xLn_x)(Ba₇,Sr_1-y)(Co_z,Tn_1-z) O_5+δ, where Ln is selected from La, Nd, Ce, Pm, Sm, Er, Gd, Dy, Ho, and Yb; Tn is selected from Fe, Ni, Cu, Zn, Mn, Cr, and Nd, 0≤x≤1, 0≤y≤1, 0≤z≤1, and δ is the oxygen deficit (e.g., Pr_0.5La_0.5BaCo₂O_5+δ (PLBC)); a double perovskite material, such as MBa_1-xSr_xCo_2-yFe_yO_5+δ, where x and y are dopant levels, δ is the oxygen deficit, and M is Pr, Nd, or Sm (e.g., PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ (PBSCF), NdBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ, SmBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ) or MBa_1-xCa_xCo₂O_5+δ, where x is a dopant level, δ is the oxygen deficit and M is Pr, Nd, or Sm (e.g., PrBa_0.8Ca_0.2Co₂O_5+δ (PBCC)); a single perovskite material, such as Sm_1-xSr_xCoO_3-δ (SSC), BaZr_1-x-y-zCo_xFe_yY₂O_3-δ, or SrSc_xNd_yCo_1-x-yO_3-δ, where x, y, and z are dopant levels and δ is the oxygen deficit; a Ruddleson-Popper-type perovskite material, such as M₂NiO_4-δ, where δ is the oxygen deficit and M is La, Pr, Gd, or Sm (e.g., La₂NiO_4-δ, Pr₂NiO_4-δ, Gd₂NiO_4-δ, Sm₂NiO_4-δ); and a single perovskite/perovskite composite material such as SSC—BZCYYb. In some embodiments, the positive electrode 112 is formed of and includes PNC55.
As another non-limiting example, if the electrolyte 114 comprises a solid acid material having an operational temperature within a range of from about 200° C. to about 400° C., the positive electrode 112 may be formed of and include one or more of a metal, an alloy, and an oxide compatible with the solid acid material of the electrolyte 114. The positive electrode 112 may, for example, be formed of and include one or more of Ni, a Ni alloy, and an Aurivillius oxide having a general formula Bi₂A_n-1B_nO_3n+3where A is chosen from Sr, Ca, Pb, Ba, K or Na, and B is chosen from Ti, Nb, Mo, Mn, Ta, Fe, or W (e.g., Bi₂Sr₂Nb₂MnO_12-δ, where δ is the oxygen deficit).
As another non-limiting example, if the electrolyte 114 comprises a PBI material having an operational temperature within a range of from about 150° C. to about 250° C., the positive electrode 112 may be formed of and include one or more of metals and alloys compatible with the PBI material of the electrolyte 114. For example, the positive electrode 112 may be formed of and include one or more of Ni, Pt, a Ni alloy, and a Pt alloy.
Optionally, the positive electrode 112 may include at least one catalyst material thereon, thereover, and/or therein. For example, at least one catalyst material may be included on, over, and/or within the material of the positive electrode 112 to accelerate (e.g., catalyze) reaction rates (e.g., water oxidation reaction rates) at the positive electrode 112 to produce H⁺ ions, oxygen, and electrons from steam in accordance with Equation (1) above.
The negative electrode 116 may be formed of and include a material compatible with the material of the electrolyte 114 and the material of the positive electrode 112 under the operating conditions (e.g., temperature, pressure, current density) of the electrochemical cell 110. The material composition of the negative electrode 116 may facilitate production of one or more hydrocarbon compounds (e.g., one or more hydrocarbon products), such as, for example, one or more light olefins (e.g., ethylene, propylene, butylene), from carbon dioxide from the CO₂stream 124, and the H⁺ ions and electrons produced from the steam of the steam stream 122. As a non-limiting example, if the electrolyte 114 includes a perovskite material (e.g., a BZCYYb, a BSNYYb, a doped BaCeO₃, a doped BaZrO₃, Ba₂(YSn)O_5.5, Ba₃(CaNb₂)O₉), the negative electrode 116 may be formed of and include at least one perovskite material compatible with the perovskite material of the electrolyte 114. For example, the negative electrode 116 may be formed of and include a cermet material comprising at least one metal (e.g., Ni) and at least one perovskite, such as a nickel/perovskite cermet (Ni-perovskite) material (e.g., Ni—BZCYYb, Ni—BSNYYb, Ni—BaCeO₃, Ni—BaZrO₃, Ni—Ba₂(YSn)O_5.5, Ni—Ba₃(CaNb₂)O₉).
As another non-limiting example, if the electrolyte 114 comprises a solid acid material having an operational temperature within a range of from about 200° C. to about 400° C., the negative electrode 116 may be formed of and include a cermet comprising at least one metal and at least one solid acid compatible with the solid acid material of the electrolyte 114. The negative electrode 116 may, for example, comprise a precious metal/solid acid cermet (e.g., Pt—CsH₂PO₄).
As another non-limiting example, if the electrolyte 114 comprises a PBI material having an operational temperature within a range of from about 150° C. to about 250° C., the negative electrode 116 may be formed of and include one or more of metals and alloys compatible with the PBI material of the electrolyte 114. For example, the negative electrode 116 may be formed of and include one or more of Ni, Pt, a Ni alloy, and a Pt alloy.
The negative electrode 116 may include at least one catalyst material that accelerates (e.g., catalyzes) reaction rates (e.g., CO₂reduction reaction rates, CO₂hydrogenation reaction rates) at the negative electrode 116 to produce at least one hydrocarbon compound from carbon dioxide, H⁺ ions and electrons. The at least one catalyst material of the negative electrode 116 may exhibit a relatively high selectivity (e.g., greater than about 40%) for the production of hydrocarbons (e.g., alkanes and olefins such as light olefins), compared to carbon monoxide. In some embodiments, the negative electrode 116 is formed of and includes the at least one catalyst material. In some embodiments, the negative electrode 116 includes the at least one catalyst material on, over, and/or within the material of the negative electrode 116. The catalyst material of the negative electrode 116 may be disposed on and between the negative electrode 116 and the electrolyte 114. The catalyst material of the negative electrode 116 may be disposed within (e.g., infiltrated into) the material of the negative electrode 116. In some embodiments, the electrolyte 114 may include the catalyst material of the negative electrode 116. The catalyst material of the negative electrode 116 may include nano-sized particles (e.g., individually having a cross-sectional width or diameter less than about one (1) μm, such as less than or equal to about 100 nm, less than or equal to about 20 nm, or less than or equal to about 10 nm). In addition, the negative electrode 116 may include any amount (e.g., concentration) and distribution of the catalyst material and any ratio of components thereof facilitating desired CO₂reduction reactions (e.g., CO₂hydrogenation reactions) at the negative electrode 116. The at least one catalyst material of the negative electrode may be formed by one or more of a precipitation method (e.g., a coprecipitation method) and a combustion method.
The at least one catalyst material of the negative electrode 116 may be, for example, an iron (Fe)-based catalyst material. The Fe-based catalyst material may include zinc (Zn) and one or more additional metals, such as, for example, zirconium (Zr), cerium (Ce), cobalt (Co), copper (Cu), manganese (Mn), and indium (In). The Fe-based catalyst material may include an alkali metal promoter, such as, for example potassium (K), sodium (Na), or any other suitable alkali metal. For example, the at least one catalyst material of the negative electrode 116 may include one or more of FeZn/K, FeZnZr/K, FeZnMn/K, FeZnCe/K, FeZnCu/K, FeZnIn/K, Fe FeZnCo/K, FeZn/Na, FeZnZr/Na, FeZnMn/Na, FeZnCe/Na, FeZnCu/Na, FeZnIn/Na, and FeZnCo/Na. In some embodiments, the at least one catalyst material of the negative electrode 116 is formed of and includes one or more of FeZnZr/K, FeZnCe/K, and FeZnCu/K. In some embodiments, the at least one catalyst material of the negative electrode 116 is formed of and include FeZnZr/K. The Fe-based catalyst material may include Fe at an amount within a range of from about 10% by mole (mol %) to about 60 mol %, such as, for example, from about 20 mol % to about 60 mol %, from about 30 mol % to about 60 mol %, from about 20 mol % to about 50 mol %, or from about 40 mol % to about 60 mol %. In some embodiments, the Fe-based catalyst includes Fe at about 50 mol %. The Fe-based catalyst material may include a molar ratio of Fe to Zn within a range of from about 1:1 to about 2:1. In some embodiments, the Fe-based catalyst material is FeZn/K and includes a molar ratio of Fe to Zn of about 1:1. In some embodiments, the Fe-based catalyst material is FeZnZr/K and includes a molar ratio of Fe to Zn to Zr of about 2:1:1. The Fe-based catalyst material may include the alkali metal promotor (e.g., K, Na, or any other suitable alkali metal) at an amount within a range of from about 0.5% by weight (wt %) to about 3 wt %, such as from about 1 wt % to about 2 wt %.
The at least one catalyst material of the negative electrode 116 may be, for example, at least one catalytic perovskite material that accelerates (e.g., catalyzes) reaction rates (e.g., CO₂reduction reaction rates, CO₂hydrogenation reaction rates) at the negative electrode 116 to produce at least one hydrocarbon compound from carbon dioxide, H⁺ ions and electrons. The at least one catalytic perovskite material may be an Fe-based perovskite material. The at least one catalytic perovskite material of the negative electrode 116 may be formed of and include at least one perovskite material including iron (Fe) and one or more of zinc (Zn), zirconium (Zr), cerium (Ce), cobalt (Co), copper (Cu), manganese (Mn), and indium (In). For example, the at least one catalytic perovskite material of the negative electrode 116 may be formed of and include one or more of a perovskite material, such as Ba(Y_1-x-y-z, Zr_x, Zn_y, Fe_z)O_3-δ, where 0≤x≤0.9, 0≤y≤0.9, 0≤z≤0.9, and δ is an oxygen deficit; or (Pr_1-xLn_x)(Ba₇,Sr_1-y)(Co_z,Tn_1-z)O_5+δ, where Ln is selected from La, Nd, Ce, Pm, Sm, Er, Gd, Dy, Ho, and Yb, Tn is selected from Fe, Ni, Cu, Zn, Zr, Mn, In, Cr, and Nd, 0≤x≤1, 0≤y≤1, 0≤z≤1, and δ is the oxygen deficit (e.g., Pr_0.5La_0.5BaCo₂O_5+δ (PLBC)); a double perovskite material, such as MBa_1-xSr_xCo_2-yFe_yO_5+δ, where x and y are dopant levels, δ is the oxygen deficit, and M is Pr, Nd, or Sm (e.g., PrBa_0.5Sr_0.5Co_0.5Fe_1.5O_5+δ (PBSCF), NdBa_0.5Sr_0.5Co_0.5Fe_1.5O_5+δ, SmBa_0.5Sr_0.5Co_0.5Fe_1.5O_5+δ) or MBa_1-xCa_xCo₂O_5+δ, where x is a dopant level, δ is the oxygen deficit and M is Pr, Nd, or Sm (e.g., PrBa_0.8Ca_0.2Co₂O_5+δ (PBCC)); a single perovskite material, such as Sm_1-xSr_xCoO_3+δ (SSC), BaZr_1-x-y-zCo_xFe_yY_zO_3-δ, or SrSc_xNd_yCO_1-x-yO_3-δ, where x, y, and z are dopant levels and δ is the oxygen deficit; a Ruddleson-Popper-type perovskite material, such as Sr₃Fe₂O_7-δ, where δ is the oxygen deficit; and a single perovskite/perovskite composite material such as Sr₃Fe₂O_7-δ—BZCYYb. In some embodiments, the negative electrode 116 is formed of and includes BaFe_0.75Zn_0.1Zr_0.1Y_0.1(BFZZY).
The positive electrode 112 and the negative electrode 116 may each individually exhibit any desired dimensions (e.g., length, width, thickness) and any desired shape (e.g., a cubic shape, cuboidal shape, a tubular shape, a tubular spiral shape, a spherical shape, a semi-spherical shape, a cylindrical shape, a semi-cylindrical shape, a conical shape, a triangular prismatic shape, a truncated version of one or more of the foregoing, and irregular shape). The dimensions and the shapes of the positive electrode 112 and the negative electrode 116 may be selected relative to the dimensions and the shape of the electrolyte 114 such that the electrolyte 114 substantially intervenes between opposing surfaces of the positive electrode 112 and the negative electrode 116. Thicknesses of the positive electrode 112 and the negative electrode 116 may each individually be within a range of from about 10 μm to about 1000 μm.
By selecting catalysts in the negative electrode 116 to exhibit a high olefin (e.g., light olefin) product selectivity, the system 100 may be used to more efficiently produce olefins compared to conventional low temperature (e.g., less than about 100° C.) electrochemical reduction of carbon dioxide in aqueous media. Additionally, since the system 100 operates intermediate operating temperatures (e.g., between about 150° C. and about 650° C.), the system 100 may be used to produce olefins at a lower material cost and may exhibit increased system durability compared to high temperature (e.g., greater than about 800° C.) carbon dioxide electrolysis using oxygen-ion conducting cells. Since heat and electricity used in the system 100 may be obtained from carbon-free processes, such as from renewable, solar, nuclear, or carbon capture processes, the olefins may be formed with significant reductions in process energy and carbon intensity compared to conventional processes. The produced olefins may be used as a precursor for manufacturing polymers, chemical intermediates, and solvents at reduced costs, greater efficiency, and reduced carbon intensity.
The electrochemical cell 110, including the positive electrode 112, the electrolyte 114, and the negative electrode 116, may be formed through conventional processes (e.g., rolling process, milling processes, shaping processes, pressing processes, consolidation processes, etc.), which are not described in detail herein. The electrochemical cell 110 may be mono-faced or bi-faced and may have a prismatic, folded, wound, cylindrical, or jelly-rolled configuration. The electrochemical cell 110 may be placed within the housing structure 108 to form the electrochemical apparatus 106, and may be electrically connected to the power source 118.
Although the electrochemical apparatus 106 is depicted as including a single (i.e., only one) electrochemical cell 110 in FIG. 1 , the electrochemical apparatus 106 may include any number of electrochemical cells 110. Put another way, the electrochemical apparatus 106 may include a single (e.g., only one) electrochemical cell 110, or may include multiple (e.g., more than one) electrochemical cells 110. If the electrochemical apparatus 106 includes multiple electrochemical cells 110, each of the electrochemical cells 110 may be substantially the same (e.g., exhibit substantially the same components, component sizes, component shapes, component material compositions, component material distributions, component positions, component orientations, etc.) and may be operated under substantially the same conditions (e.g., substantially the same temperatures, pressures, flow rates, etc.), or at least one of the electrochemical cells 110 may be different (e.g., exhibit one or more of different components, different component sizes, different component shapes, different component material compositions, different component material distributions, different component positions, different component orientations, etc.) than at least one other of the electrochemical cells 110 and/or may be operated under different conditions (e.g., different temperatures, different pressures, different flow rates, etc.) than at least one other of the electrochemical cells 110. By way of non-limiting example, one of the electrochemical cells 110 may be configured for and operated under a different temperature (e.g., different operating temperature resulting from a different material composition of one of more components thereof, such as a different material composition of the electrolyte 114 thereof) than at least one other of the electrochemical cells 110. In some embodiments, two or more electrochemical cells 110 are provided in parallel with one another within the housing structure 108 of the electrochemical apparatus 106, and may individually produce a portion of the hydrocarbon compounds (e.g., ethylene, propylene, butylene, etc.) directed out of the electrochemical apparatus 106 as the hydrocarbon product stream 126.
Still referring to FIG. 1 , the oxygen stream 128 and the hydrocarbon product stream 126 exiting the electrochemical apparatus 106 may individually be utilized or disposed of as desired. In some embodiments, the oxygen stream 128 and the hydrocarbon product stream 126 are individually delivered into one or more storage vessels (not shown) for subsequent use, as desired. In additional embodiments, at least a portion of one or more of the oxygen stream 128 and the hydrocarbon product stream 126 may be utilized (e.g., combusted) to heat one or more components (e.g., the heating apparatus 120 (if present); the electrochemical apparatus 106; etc.) and/or streams (e.g., the steam stream 122, the oxygen stream 128) of the system 100. By way of non-limiting example, if the heating apparatus 120 (if present) is a combustion-based apparatus, at least a portion of one or more of the oxygen stream 128 and the hydrocarbon product stream 126 may be directed into the heating apparatus 120 and undergo a combustion reaction to efficiently heat one or more of the steam stream 122 entering the electrochemical apparatus 106, the carbon dioxide stream 124 entering the electrochemical apparatus 106, and at least a portion of the electrochemical apparatus 106. Utilizing the oxygen stream 128 and/or the hydrocarbon product stream 126 as described above may reduce the electrical power requirements of the system 100 by enabling the utilization of direct thermal energy. Unreacted CO₂and byproducts (e.g., carbon monoxide, methane) and H₂O produced at the negative electrode 116 may be separated from the hydrocarbon product stream 126 and individually introduced into one or more storage vessels (not shown) for subsequent use, as desired. In some embodiments, the unreacted carbon dioxide and carbon monoxide, if any, separated from the hydrocarbon product stream 126 are delivered into the electrochemical apparatus 106 as a carbon dioxide recycle stream (not shown) to interact with the negative electrode 116. The hydrocarbon product stream 126 may be recovered and used as precursor materials for manufacturing polymers, chemical intermediates, and solvents in the chemical industry. In addition to the hydrocarbon product stream 126, the oxygen stream 128 may be a useful co-product of the system and methods according to embodiments of the disclosure.
Thermal energy input into (e.g., through the heating apparatus 120 (if present)) and/or generated by the electrochemical apparatus 106 may also be used to heat one or more other components and/or streams of the system 100. By way of non-limiting example, the oxygen stream 128 and/or the hydrocarbon product stream 126 exiting the electrochemical apparatus 106 may be directed into a heat exchanger configured and operated to facilitate heat exchange between the oxygen stream 128 and/or the hydrocarbon product stream 126 of the system 100 and one or more other relatively cooler streams (e.g., the steam stream 122, the carbon dioxide stream 124) of the system 100 to transfer heat from the oxygen stream 128 and/or the hydrocarbon product stream 126 to the relatively cooler stream(s) to facilitate the recovery of the thermal energy input into and generated within the electrochemical apparatus 106. The recovered thermal energy may increase process efficiency and/or reduce operational costs without having to react (e.g., combust) oxygen of the oxygen stream 128 and/or the hydrocarbon compounds of the hydrocarbon product stream 126.
FIG. 2 illustrates a simplified cross-sectional view of an electrochemical cell 210 for producing the hydrocarbon compounds (e.g., olefins, light olefins) from carbon dioxide, according to embodiments of the disclosure. The electrochemical cell 210 may be at least substantially similar to the electrochemical cell 110 previously described with reference to FIG. 1 . The electrochemical cell 210 may include a positive electrode 212, a negative electrode 216, an electrolyte 214, and a negative electrode catalyst material 236 disposed between the negative electrode 216 and the electrolyte 214. The negative electrode catalyst material 236 may be at least substantially similar to the at least one catalyst material of the negative electrode 116 previously described with reference to FIG. 1 .
FIG. 3 illustrates a simplified cross-sectional view of an electrochemical cell 310 for producing ethylene from carbon dioxide according to embodiments of the disclosure. The electrochemical cell 310 may be at least substantially similar to the electrochemical cell 110 previously described with reference to FIG. 1 . The electrochemical cell 310 may produce ethylene using electricity and heat produced from carbon-free processes, such as from renewable, solar, nuclear, or carbon capture processes, and steam produced from a carbon-free process. Thus, the ethylene may be formed with significant reductions in process energy and carbon intensity compared to conventional processes.
FIG. 4 illustrates a simplified schematic view of a system 400 for producing the hydrocarbon compounds (e.g., olefins, light olefins) from carbon dioxide according to embodiments of the disclosure. The system 400 may be at least substantially similar to the system 100 previously described with reference to FIG. 1 . The system 400 may include additional process components (e.g., separators, recycled streams, storage vessels, etc.) to achieve the separation and recycling shown in FIG. 4 .
The electrochemical cells (e.g., the electrochemical cells 110, 210, 310), systems (e.g., the systems 100, 400), and methods of the disclosure enable industrial decarbonization by valorizing carbon dioxide emitted from point sources such as fossil fuel power plants, oil refineries, industrial process plants, and other heavy industrial sources. Utilizing carbon dioxide emissions to form valuable chemicals and/or fuels (e.g., hydrocarbons, olefins, light olefins) may reduce or eliminate the carbon intensity of industrial processes and increase economic revenues. Combined with carbon dioxide capture technologies, the electrochemical cells, systems, and methods of the disclosure may reduce the need to use fossil-based resources to produce olefin products as well as provide an increased yield of the light olefins (e.g., ethane) per unit volume of catalyst and per unit time. The electrochemical cells, systems, and methods of the disclosure may also reduce one or more of the costs, (e.g., material costs, operational costs) and energy (e.g., thermal energy, electrical energy) utilized to produce hydrocarbons and/or generate electricity relative to conventional electrochemical cells, systems, and methods. The electrochemical cells, systems, and methods of the disclosure may be more efficient, durable, and reliable than conventional electrochemical cells, conventional systems, and conventional methods of hydrocarbon and electricity production.
The electrochemical cells (e.g., the electrochemical cell 110, 210, 310), systems (e.g., the systems 100, 400), and methods of the disclosure may enable the production of the light olefins, which are in turn used to form products such as plastics or aviation fuel.
The following examples serve to explain embodiments of the disclosure in more detail. These examples are not to be construed as being exhaustive, exclusive, or otherwise limiting as to the scope of the disclosure.

EXAMPLES

Example 1: Catalyst Synthesis

An iron oxide based FeZn/K catalyst was synthesized by a coprecipitation method. FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, and FeZnIn/K were synthesized by adding one of Zr, Ce, Co, Cu, Mn, or In to the FeZn/K. FeInZr/K, FeCoZr/K, and FeCeZr/K were synthesized by a coprecipitation method.

Example 2: Catalyst Performance Evaluations

Performance evaluations of FeZn/K, FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, FeZnIn/K, FeInZr/K, FeCoZr/K, and FeCeZr/K as described in Example 1, were conducted in a packed bed flow reactor. A gas chromatograph (GC) was used to analyze the products to determine a carbon dioxide conversion and product selectivity.
To evaluate the catalytic performance of FeZn/K, the packed bed flow reactor including the FeZn/K was heated to 340° C. under atmospheric pressure, and carbon dioxide and hydrogen at a molar ratio of 1:3 were allowed to flow through the packed bed flow reactor. The carbon dioxide conversion was about 20%, and the major product formed was carbon monoxide with a selectivity of greater than 90%. Hydrocarbon products including methane, ethylene, ethane, and propylene were also detected. The ethylene selectivity was below 1% at 340° C. under atmospheric pressure.
To evaluate the catalytic performance of FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, and FeZnIn/K in comparison to FeZn/K, each of FeZn/K, FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, and FeZnIn/K were individually evaluated by incorporating each individually in a packed bed flow reactor and allowing carbon dioxide and hydrogen at a molar ratio of 1:3 to flow through the packed bed flow reactor. The products were analyzed with a GC.
FIG. 5A is a graphical comparison of carbon dioxide (CO₂) conversion observed for each of FeZn/K, FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, and FeZnIn/K at a temperature of about 350° C. and a pressure of 0.1 Megapascals (MPa). FIG. 5B is a graphical comparison of carbon monoxide (CO) selectivity and hydrocarbon (C_xH_y) product selectivity of FeZn/K, FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, and FeZnIn/K at a temperature of about 350° C. and a pressure of 0.1 MPa. As shown in FIG. 5B, hydrocarbon products were detected when FeZnZr/K and FeZnCe/K were used, with FeZnZr/K showing a higher selectivity to hydrocarbon products.
The catalytic performance of each of FeInZr/K, FeCoZr/K, and FeCeZr/K was determined under the same conditions as of FeZn/K, FeZnZr/K, FeZnCe/K, FeZnCo/K, FeZnCu/K, FeZnMn/K, and FeZnIn/K described above. In comparison with FeZnZr/K, FeZnZr/K exhibited a higher CO₂conversion and hydrocarbon (e.g., olefin) selectivity than each of FeInZr/K, FeCoZr/K, and FeCeZr/K.
To evaluate the performance of the catalyst based on the identity of the alkali metal promotor, FeZnZr/Na was synthesized. FeZnZr/Na was evaluated under the same conditions as FeZnZr/K described above. In comparison with FeZnZr/K, the CO₂conversion of FeZnZr/Na was slightly lower than the CO₂conversion of FeZnZr/K and an olefin selectivity in the hydrocarbon products using the FeZnZr/Na was about 8% higher than the olefin selectivity in the hydrocarbon products using the FeZnZr/K. The overall hydrocarbon selectivity of FeZnZr/Na was relatively lower than that of FeZnZr/K.
The influence of elemental composition and preparation method were also investigated. An increase in Fe or Zr content of FeZnZr/K resulted in deteriorated activity and hydrocarbon product selectivity. When prepared via a combustion method instead of the coprecipitation method of Example 1, the catalysts exhibited lower olefin product selectivity and slightly lower CO₂conversions.

Example 3: Reaction Parameter Evaluations

Carbon dioxide reduction (e.g., CO₂hydrogenation) reaction parameters including temperature, H₂/CO₂ratio, pressure, and space velocity were investigated using FeZnZr/K as a catalyst material for a CO₂hydrogenation reaction.
FIG. 6A is a graphical comparison of product selectivity and CO₂conversion of the CO₂hydrogenation reaction conducted at different reaction temperatures. As shown in FIG. 6A, a higher temperature resulted in higher CO₂conversion. The olefin product selectivity increased from about 45% at 300° C. to about 61% at 350° C. and then decreased to about 51% and 31% at 400° C. and 450° C., respectively. As shown in FIG. 6A, a higher reaction temperature favored the formation of carbon monoxide (CO) and methane (CH₄), and the CO and CH₄selectivity demonstrated an increase as the temperature increased from 350° C. to 450° C.
FIG. 6B is a graphical comparison of product selectivity and CO₂conversion of the CO₂hydrogenation reaction conducted at different reaction pressures. As shown in FIG. 6B, a higher pressure resulted in lower CO₂conversion. As the pressure increased from 0.1 to 0.2 MPa, the CO₂conversion dropped from about 34% to about 25%. Further increase in the pressure up to 0.6 MPa resulted in a decrease of the CO₂conversion to about 22%. As shown in FIG. 6B, as the pressure increased from 0.1 MPa to 0.6 MPa, the product selectivity changed from carbon monoxide dominant to hydrocarbon dominant. The CO selectivity decreased from about 83% to about 33% as the pressure increased from 0.1 MPa to 0.6 MPa, while the hydrocarbon product selectivity, including light olefins (e.g., C₂₊ ⁼), increased from about 17% to about 67%.
FIG. 6C is a graphical comparison of product selectivity and CO₂conversion of the CO₂hydrogenation reaction conducted with different H₂/CO₂ratios. As shown in FIG. 6C, carbon monoxide is the dominant product under H₂-lean conditions (e.g., a ratio of less than 1 of H₂/CO₂). The selectivity of hydrocarbon products, including light olefins (e.g., C₂₊ ⁼), increased from about 16% to about 78% as the H₂/CO₂ratio increased from 0.1 to 9. The saturated hydrocarbon product selectivity, including methane (CH₄) and ethane (C₂H₆), demonstrated an increase at high H₂/CO₂ratios.
FIG. 6D is a graphical comparison of product selectivity and CO₂conversion of the CO₂hydrogenation reaction conducted with different space velocities (SV) of the feed gas. The SV of the feed gas determines the residence time of the reactants on the catalyst surface. As shown in FIG. 6D, as the SV increased from 1500 h⁻¹to 24000 h⁻¹, the CO₂conversion initially decreased from about 36% to about 16% until the SV reached 6000 h⁻¹and then plateaued at about 16%. The corresponding olefin selectivity exhibited a decrease as the SV increased from 1500 h⁻¹to 24000 h⁻¹.

Example 4: Perovskite Catalyst Synthesis

A catalyst with the composition of BaFe_0.75Zn_0.1Zr_0.1Y_0.1(BFZZY) was synthesized by a sol-gel method and calcined at different temperatures to form the perovskite phase structure. The perovskite phase structure was confirmed by X-ray diffraction characterization.

Example 5: Cell Fabrication

Ni-cermet electrode-supported protonic ceramic electrochemical cells (PCECs) were fabricated in the form of 1 inch-button cells. A NiO/BCZZYb anode backbone layer was fabricated by a tape-casting process and a pre-sintering process was conducted at 900° C. An electrolyte layer including BCZYYb was applied by a spray-coating process to form a two-layer half-cell. The two-layer half-cell was co-fired at a temperature between about 1400° C. to about 1450° C. for about 5 hours. PNC55 was infiltrated into the anode backbone to improve water oxidation reaction activity and to reduce the anode overpotential. To form a control cell for comparison purposes, a cathode including PNC55 was formed on the electrolyte layer. The anode exhibited a thickness of about 20 micrometers (μm). The electrolyte exhibited a thickness of about 10 μm. The cathode exhibited a thickness of about 20 μm.
To evaluate the catalytic performance of the FeZnZr/K catalyst, as described in Examples 1 and 2, about 20 mg of the FeZnZr/K catalyst was integrated into a 1 inch-button cell, by brush painting the FeZnZr/K onto the BCZYYb electrolyte, between the electrolyte and the negative electrode.
To evaluate the electrochemical performance of a PCEC including BFZZY, as described in Example 4 above, BFZZY was used as the negative electrode in a button cell. BFZZY was integrated into the button cell by brush painting BFZZY onto the BCZYYb electrolyte of a half-cell including the BCZYYb electrode and the NiO/BCZYYb anode without a firing treatment.

Example 6: Catalytic Performance Evaluations in PCECs

The catalytic performance of the FeZnZr/K catalyst, as described in Examples 1 and 2, was tested by feeding an H₂feedstock to the anodes and a CO₂feedstock to the cathodes of the respective 1 inch-button cells described in Example 5. A GC was used to analyze the product stream from the cathodes of the 1 inch-button cells.
To evaluate the catalytic performance of the FeZnZr/K catalyst, CO₂conversion and product selectivity were determined under different applied currents. FIG. 7A is a graphical comparison of the product selectivity of carbon monoxide and hydrocarbons, and the CO₂conversion of the 1 inch-button cell including the FeZnZr/K catalyst under different applied currents. The CO₂conversion increased from about 11.3% to about 18.6% as the applied current increased from −0.2 A cm⁻²to −1.0 A cm⁻². There was no substantial change in the hydrocarbon product selectivity relative to carbon monoxide as the applied current increased. FIG. 7B is a graphical comparison of hydrocarbon product selectivity and voltage of the 1 inch-button cell including the FeZnZr/K catalyst under different applied currents. As shown in FIG. 7B, the C₂and C₃₊ products selectivity relative to CH₄increased with an increase in applied current from −0.2 A cm⁻²to −0.8 A cm⁻². The C₂product selectivity decreased with a further increase in applied current from −0.8 A cm⁻²to −1.0 A cm⁻².

Example 7: Electrochemical Performance of BFZZY

The electrochemical performance of the PCEC including BFZZY, as described in Example 4 above, was evaluated. FIG. 8A is a current density vs. voltage plot (e.g., polarization curve) and a current density vs. power density plot (e.g., power density curve) of the PCEC including BFZZY operated as an electrolysis cell at 600° C. using H₂and O₂as the feed gases to the anode and the cathode, respectively. FIG. 8B illustrates a Cole-Cole plot obtained from electrochemical impedance spectroscopy (EIS) measurements, of the PCEC including BFZZY operated as an electrolysis cell at 600° C. using H₂and O₂as the feed gases to the anode and the cathode, respectively, where the x-axis is Z′ and the y-axis is —Z″, where Z′ and Z″ are the real and imaginary parts of the complex impedance, respectively. FIGS. 8A and 8B show that peak power density (PPD) of 373 mW cm⁻²was obtained at 600° C., with an ohmic resistance R_o(shown by the left intercept of the EIS curve with the x-axis) of 0.34 (2 cm²and a polarization resistance R_p(shown by the right intercept of the EIS curve with the x-axis minus R_o) of 0.14 Ωcm².
FIG. 8C is a current density vs. voltage plot (e.g., polarization curve) and a current density vs. power density plot (e.g., power density curve) of the PCEC including BFZZY operated at 600° C. using H₂as the feed gas to the anode and CO₂at different concentrations (e.g., 10% by volume (vol %), 40 vol %, and 100 vol %) as the feed gas to the cathode. FIG. 8D illustrates a Cole-Cole plot obtained from EIS measurements the PCEC including BFZZY operated at 600° C. using H₂as the feed gas to the anode and CO₂at different concentrations (e.g., 10 vol %, 40 vol %, and 100 vol %) as the feed gas to the cathode, where the x-axis is Z′ and the y-axis is —Z″, where Z′ and Z″ are the real and imaginary parts of the complex impedance, respectively. FIGS. 8C and 8D show that as a CO₂concentration in the feed gas to the cathode was increased from 10 vol % to 40 vol % to 100 vol %, the PPD increased from about 31 mW cm⁻²to about 41 mW cm⁻²to about 46 mW cm⁻², respectively. The ohmic resistance R_oand the polarization resistance R_palso decreased with an increase in CO₂concentration.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, the disclosure is not limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the following appended claims and their legal equivalent. For example, elements and features disclosed in relation to one embodiment may be combined with elements and features disclosed in relation to other embodiments of the disclosure.

Claims

What is claimed is:

1. A method of forming at least one hydrocarbon from carbon dioxide, comprising: introducing steam to a first electrode of an electrochemical cell comprising:

the first electrode;

a second electrode comprising at least one catalyst material formulated to accelerate a carbon dioxide hydrogenation reaction to produce the at least one hydrocarbon product from the carbon dioxide; and

an electrolyte between the first electrode and the second electrode;

introducing carbon dioxide to the second electrode of the electrochemical cell; and

applying a potential difference between the first electrode and the second electrode of the electrochemical cell.

2. The method of claim 1, wherein introducing the steam to the first electrode of the electrochemical cell includes introducing the steam to the first electrode of the electrochemical cell comprising the second electrode, the at least one catalyst material of the second electrode comprising at least one iron (Fe)-based catalyst material and an alkali metal promotor.

3. The method of claim 1, wherein applying a potential difference between the first electrode and the second electrode of the electrochemical cell comprises producing the at least one hydrocarbon including an alkane, an olefin, or a combination thereof.

4. The method of claim 1, wherein applying a potential difference between the first electrode and the second electrode of the electrochemical cell comprises producing a reaction product comprising:

carbon monoxide; and

the at least one hydrocarbon in an amount of greater than about 40% by weight based on a total weight of the reaction product.

5. The method of claim 1, wherein introducing carbon dioxide to the second electrode of the electrochemical cell comprises:

introducing the carbon dioxide to a second electrode comprising the at least one catalyst material including: FeZn/K, FeZnZr/K, FeZnMn/K, FeZnCe/K, FeZnCu/K, FeZnIn/K, Fe FeZnCo/K, FeZn/Na, FeZnZr/Na, FeZnMn/Na, FeZnCe/Na, FeZnCu/Na, FeZnIn/Na, FeZnCo/Na, or a combination thereof.

6. The method of claim 1, wherein introducing carbon dioxide to the second electrode of the electrochemical cell comprises introducing the carbon dioxide to a second electrode comprising:

the at least one iron (Fe)-based catalyst comprising FeZnZr; and

the alkali metal promotor comprising K, Na, Cs, or a combination thereof.

7. The method of claim 1, wherein applying a potential difference between the first electrode and the second electrode of the electrochemical cell comprises applying the potential difference to the electrochemical cell when the electrochemical cell fulfills at least one of the following:

the electrochemical cell is operated at a temperature within a range of from about 150° C. to about 650° C.,

the electrochemical cell is operated at a pressure within a range of from about 1 bar to about 20 bar, and

the electrochemical cell is operated at a current density greater than or equal to about 0.1 amperes per square centimeter (A/cm²).

8. An electrochemical cell, comprising:

a first electrode formulated to facilitate an oxidation reaction of water to produce oxygen;

a second electrode formulated to facilitate a reduction reaction of carbon dioxide to produce at least one hydrocarbon, the second electrode comprising at least one catalyst material formulated to accelerate the reduction reaction of the carbon dioxide; and

an electrolyte between the first electrode and the second electrode.

9. The electrochemical cell of claim 8, wherein the at least one catalyst material of the second electrode comprises an iron (Fe)-based catalyst material including iron (Fe), zinc (Zn), and at least one of zirconium (Zr), cerium (Ce), cobalt (Co), copper (Cu), manganese (Mn), and indium (In).

10. The electrochemical cell of claim 8, wherein the electrolyte comprises a perovskite material, a solid acid material, a polybenzimidazole material, or a combination thereof.

11. The electrochemical cell of claim 10, wherein:

the perovskite material has a formula ABO_3-δ, wherein A comprises barium (Ba), B comprises zirconium (Zr), cerium (Ce), yttrium (Y), ytterbium (Yb) or a combination thereof, and δ is the oxygen deficit;

the solid acid material comprises a solid acid phosphate material; and

the polybenzimidazole material comprises a H₃PO₄-doped polybenzimidazole material.

12. The electrochemical cell of claim 8, wherein:

the first electrode comprises a triple conducting perovskite material, a double perovskite material, a single perovskite material, a single perovskite/perovskite composite material, or a combination thereof;

the second electrode comprises a cermet material including at least one metal and at least one perovskite; and

the electrolyte comprises a perovskite material including a yttrium- and ytterbium-doped barium-zirconate-cerate (BZCYYb), a yttrium- and ytterbium-doped barium-strontium-niobate (BSNYYb), a doped BaCeO₃, a doped BaZrO₃, Ba₂(YSn)O_5.5, Ba₃(CaNb₂)O₉), or a combination thereof.

13. The electrochemical cell of claim 12, wherein:

the triple conducting perovskite material comprises Pr(Co_1-x-y-z, Ni_x, Mn_y, Fe_z)O_3-δ, wherein 0≤x≤0.9, 0≤y≤0.9, 0≤z≤0.9, and δ is an oxygen deficit; or (Pr_1-xLn_x)(Ba₇,Sr_1-y)(Co_z,Tn_1-z)O_5+δ, wherein Ln comprises La, Nd, Ce, Pm, Sm, Er, Gd, Dy, Ho, Yb or a combination thereof, Tn comprises Fe, Ni, Cu, Zn, Mn, Cr, Nd or a combination thereof, 0≤x≤1, 0≤y≤1, 0≤z≤1, and δ is the oxygen deficit;

the double perovskite material comprises MBa_1-xSr_xCo_2-yFe_yO_5+δ, wherein x and y are dopant levels, δ is the oxygen deficit, and M comprises Pr, Nd, Sm or a combination thereof; or MBa_1-xCa_xCo₂O_5+δ, wherein x is a dopant level, δ is the oxygen deficit and M comprises Pr, Nd, Sm or a combination thereof;

the single perovskite material comprises Sm_1-xSr_xCoO_3-δ (SSC), BaZr_1-x-y-zCo_xFe_yY_zO_3-δ, SrSc_xNd_yCo_1-x-yO_3-δ, wherein x, y, and z are dopant levels and δ is the oxygen deficit, or a Ruddleson-Popper-type perovskite material, wherein δ is the oxygen deficit and M comprises La, Pr, Gd, Sm or a combination thereof; and

the single perovskite/perovskite composite material comprises SSC—BZCYYb.

14. The electrochemical cell of claim 12, wherein the cermet material of the second electrode comprises a nickel/perovskite cermet material including Ni—BZCYYb, Ni—BSNYYb, Ni—BaCeO₃, Ni—BaZrO₃, Ni—Ba₂(YSn)O_5.5, Ni—Ba₃(CaNb₂)O₉), or a combination thereof.

15. The electrochemical cell of claim 8, wherein:

the first electrode comprises a metal, an alloy, an Aurivillius oxide or a combination thereof, the Aurivillius oxide having a general formula Bi₂A_n-1B_nO_3n+3, wherein A comprises Sr, Ca, Pb, Ba, K, Na or a combination thereof, and B comprises Ti, Nb, Mo, Mn, Ta, Fe, W or a combination thereof;

the second electrode comprises a precious metal-solid acid cermet; and

the electrolyte comprises a solid acid material.

16. The electrochemical cell of claim 15, wherein:

the first electrode comprises Ni, a Ni alloy, an Aurivillius oxide having a general formula of Bi₂Sr₂Nb₂MnO_12-δ, wherein δ is the oxygen deficit; and

the precious metal-solid acid cermet of the second electrode comprises Pt—CsH₂PO₄.

17. The electrochemical cell of claim 8, wherein:

the first electrode and the second electrode each independently comprises Ni, Pt, a Ni alloy, a Pt alloy, or a combination thereof; and

the electrolyte comprises a polybenzimidazole material.

18. A system for producing one or more hydrocarbon from carbon dioxide, comprising:

an electrochemical apparatus in fluid communication with a first vessel configured to contain steam and a second vessel configured to contain carbon dioxide, the electrochemical apparatus comprising:

a housing structure configured and positioned to receive a steam stream from the first vessel and to receive a carbon dioxide stream from the second vessel; and

electrochemical cells within the housing structure, one or more of the electrochemical cells individually comprising:

a first electrode;

a second electrode comprising at least one catalyst material formulated to accelerate a carbon dioxide hydrogenation reaction to produce the one or more hydrocarbon from the carbon dioxide, the at least one catalyst material including a perovskite-based material containing iron (Fe) and one or more of zinc (Zn), zirconium (Zr), cerium (Ce), cobalt (Co), copper (Cu), manganese (Mn), and indium (In); and

an electrolyte between the first electrode and the second electrode.

19. The system of claim 18, wherein:

the second electrode comprises NiO/BZCYYb (yttrium- and ytterbium-doped barium-zirconate-cerate), and PrNi_0.5Co_0.5O_3-δ (PNC55); and

the at least one catalyst material of the second electrode comprises BaFe_0.75Zn_0.1Zr_0.1Y_0.1(BFZZY).

20. The system of claim 18, wherein the electrolyte comprises a proton-conducting membrane.