Electrochemical co-production of hydrogen and carbon monoxide

Abstract

A process for co-production of carbon monoxide and hydrogen is discussed herein, the process comprising: (a) providing an electrochemical reactor having an anode, a cathode, and a hybrid conductive membrane positioned between the anode and the cathode; (b) introducing a first stream into the anode, wherein the first stream comprises a fuel; (c) introducing a second stream into the cathode wherein the second stream comprises carbon dioxide and water wherein carbon monoxide is electrochemically generated from carbon dioxide and hydrogen is electrochemically generated from water. In an embodiment, the anode and the cathode are separated by the membrane, and both are exposed to a reducing environment during the entire operating time.

Description

Technical Field

[0001] The present invention generally relates to the co-production of hydrogen (H2) and carbon monoxide (CO). More specifically, the present invention relates to the electrochemical co-production of hydrogen (H2) and carbon monoxide (CO). Background Art

[0002] Carbon monoxide (CO) is a colorless, odorless, tasteless, and flammable gas with a density slightly lower than air. It is well-known for its toxic effects because CO readily binds to hemoglobin to produce carboxyhemoglobin, which is highly toxic when the concentration exceeds a certain level. However, CO is a key component in many chemical and industrial processes. CO has a wide range of functions in all branches of chemistry, such as metal carbonyl catalysis, radical chemistry, cationic and anionic chemistry. Carbon monoxide is a strong reducing agent and has been used for centuries in pyrometallurgy to reduce metals from ores. As an example of the manufacture of specialty compounds, CO is used in the production of vitamin A.

[0003] The petroleum and chemical industries require large amounts of hydrogen (H2). For example, large amounts of hydrogen are used to upgrade fossil fuels and produce methanol or hydrochloric acid. Petrochemical plants require hydrogen for hydrocracking, hydrodesulfurization, and hydrodealkylation. The hydrogenation process for increasing the saturation of unsaturated fats and oils also requires hydrogen. Hydrogen is also a reducing agent for metal ores. Hydrogen can be produced by electrolysis of water, steam reforming, laboratory-scale metal-acid methods, thermochemical methods, or anaerobic corrosion. Many countries are committed to developing a hydrogen economy.

[0004] In the Fischer-Tropsch synthesis process, both CO and H2 are essential building blocks, which are typically produced by converting carbon-rich feedstocks (e.g., coal). A mixture of CO and H2 - syngas - can combine to produce various liquid fuels, for example, via the Fischer-Tropsch synthesis process. Syngas can also be converted into lighter hydrocarbons, methanol, ethanol, or plastic monomers (e.g., ethylene). To produce the desired compounds, the CO / H2 ratio is important in all such processes. Conventional techniques require large and expensive separation and purification processes to obtain CO and H2 as building blocks.

[0005] Obviously, the demand and interest in developing new technology platforms for producing these building blocks and valuable products are increasing day by day. The present disclosure discusses the co-production of CO and H2 via an efficient electrochemical route. In addition, the methods and systems disclosed herein do not require the large and expensive separation and purification processes required in traditional technologies. Summary of the Invention

[0006] This document discusses a method for co-producing carbon monoxide and hydrogen, which method comprises: (a) providing an electrochemical reactor having an anode, a cathode, and a mixed-conducting membrane disposed between the anode and the cathode; (b) introducing a first stream into the anode, wherein the first stream contains a fuel; (c) introducing a second stream into the cathode, wherein the second stream contains carbon dioxide and water, wherein carbon monoxide is electrochemically generated from carbon dioxide, and hydrogen is electrochemically generated from water. In various embodiments, the second stream additionally contains hydrogen or carbon monoxide to ensure a true reducing environment at the cathode throughout the operation of the reactor.

[0007] In an embodiment, the anode and the cathode are separated by a membrane, and both are exposed to a reducing environment throughout the operating time. In an embodiment, the cathode comprises Ni or NiO and a material selected from the group consisting of: YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof. In an embodiment, the anode, the cathode, and the membrane have the same elements. In an embodiment, the anode, the cathode, and the membrane comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST-SCZ.

[0008] In an embodiment, the anode comprises Ni or NiO and a material selected from the group consisting of: YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof. In an embodiment, the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, or combinations thereof.

[0009] In an embodiment, the anode is liquid during operation. In an embodiment, the anode comprises tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), Babbitt metal, or combinations thereof. In an embodiment, the anode comprises lithium carbonate, potassium carbonate, sodium carbonate, or combinations thereof. In an embodiment, the fuel comprises carbon, ammonia, syngas, hydrogen, methanol, carbon monoxide, hydrocarbons, biodiesel, renewable natural gas, biogas, biomass, biowaste, charcoal, petroleum coke, edible oil, or combinations thereof.

[0010] In an embodiment, the anode comprises doped or undoped cerium dioxide and a material selected from the group consisting of: Cu, CuO, Cu2O, Ag, Ag2O, Au, Au2O, Au2O3, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, stainless steel, and combinations thereof. In an embodiment, the fuel comprises hydrocarbons.

[0011] In one embodiment, the membrane comprises an electronically conducting phase and an ionically conducting phase. In an embodiment, the electronically conducting phase comprises doped lanthanum chromite or an electronically conductive metal or a combination thereof; and wherein the ionically conducting phase comprises a material selected from the group consisting of gadolinium- or samarium-doped ceria, yttria-stabilized zirconia (YSZ), lanthanum strontium gallium magnesium oxide (LSGM), scandia-stabilized zirconia (SSZ), Sc- and Ce-doped zirconia (SCZ), and combinations thereof.

[0012] In an embodiment, the membrane comprises CoCGO or zirconia stabilized by LST (lanthanum-doped strontium titanate). In an embodiment, the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria stabilized zirconia). In an embodiment, LST comprises LaSrCaTiO3. In an embodiment, the membrane comprises nickel-, copper-, cobalt-, or niobium-doped zirconia.

[0013] In an embodiment, the cathode exhaust passes through a separator, where the generated carbon monoxide and hydrogen are separated from the exhaust. In an embodiment, the method comprises using the separated CO and H2 to produce methanol, ethanol, hydrocarbons, plastic monomers, polyethylene, or combinations thereof. In an embodiment, the reactor does not include interconnects and does not include a current collector. In an embodiment, the reactor does not generate electricity and does not receive electricity.

[0014] Additional aspects and embodiments are provided in the following figures, detailed description, and claims. Unless otherwise specified, the features described herein are combinable, and all such combinations are within the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following drawings are provided to illustrate certain embodiments described herein. The drawings are illustrative only and are not intended to limit the scope of the claimed invention, nor are they intended to illustrate every potential feature or embodiment of the claimed invention. The drawings are not necessarily to scale; in some instances, certain elements in the figures may be enlarged relative to other elements in the figures for illustrative purposes.

[0016] Figure 1A An electrochemical (EC) reactor or electrochemical gas generator according to an embodiment of the present disclosure is illustrated.

[0017] Figure 1B An electrochemical (EC) reactor or electrochemical gas generator according to an alternative embodiment of the present disclosure is illustrated.

[0018] Figure 2A A tubular electrochemical reactor according to an embodiment of the present disclosure is illustrated.

[0019] Figure 2B A cross-section of a tubular electrochemical reactor according to an embodiment of the present disclosure is illustrated.

[0020] Figure 3 Illustrated is a CO and H2 co-production system with an electrochemical reactor according to an embodiment of the present disclosure. Detailed implementation manners

[0021] Overview

[0022] Unless otherwise specified herein, the following terms and phrases have the meanings indicated below. The present disclosure may employ other terms and phrases that are not explicitly defined herein. For those of ordinary skill in the art, these other terms and phrases should have the meanings they have in the context of the present disclosure. In some cases, a term or phrase may be defined as singular or plural. In such cases, it should be understood that any singular term may include its plural counterpart, and vice versa, unless the contrary is explicitly stated.

[0023] As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" include plural referents. For example, reference to "a substituent" includes a single substituent as well as two or more substituents, etc. As used herein, "for example", "for instance", "such as", or "including" are intended to introduce examples that further clarify a more general subject. Unless otherwise explicitly stated, these examples are provided only to assist in understanding the embodiments illustrated in the present disclosure and are not meant to be limiting in any way. These phrases also do not indicate any kind of preference for the disclosed embodiments.

[0024] As used herein, unless otherwise stated, the terms "composition" and "material" may be used interchangeably. Each composition / material may have multiple elements, phases, and components. Heating as used herein refers to the active addition of energy to a composition or material.

[0025] As used herein, YSZ refers to yttria-stabilized zirconia; SDC refers to samarium-doped ceria; SSZ refers to scandia-stabilized zirconia; LSGM refers to lanthanum strontium gallium magnesium oxide.

[0026] In the present disclosure, "not having a large amount of H2" means that the volume content of hydrogen is not more than 5%, or not more than 3%, or not more than 2%, or not more than 1%, or not more than 0.5%, or not more than 0.1%, or not more than 0.05%.

[0027] As used herein, CGO refers to gadolinium-doped ceria, also known as gadolinium-doped cerium oxide, gadolinium-doped ceria, cerium(IV) oxide, gadolinium-doped GDC, or GCO (chemical formula Gd:CeO2). Unless otherwise specified, CGO and GDC can be used interchangeably. Syngas (i.e., synthesis gas) in the present disclosure refers to a mixture mainly composed of hydrogen, carbon monoxide, and carbon dioxide.

[0028] A mixed conducting membrane is capable of transporting both electrons and ions. Ionic conductivity includes ionic species such as oxygen ions (or oxide ions), protons, halide anions, chalcogenide anions. In various embodiments, the mixed conducting membrane of the present disclosure includes an electron conducting phase and an ionic conducting phase.

[0029] In the present disclosure, the axial cross-sectional view of the tube is shown as circular, which is illustrative only and not restrictive. The axial cross-section of the tube can be any suitable shape known to those skilled in the art, such as square, rounded square, rectangle, rounded rectangle, triangle, hexagon, pentagon, ellipse, irregular shape, etc.

[0030] As used herein, ceria refers to cerium oxide, also known as ceric oxide, ceric dioxide, or cerium dioxide, which is an oxide of the rare earth metal cerium. Doped ceria refers to ceria doped with other elements, such as samarium-doped ceria (SDC), or gadolinium-doped ceria (GDC or CGO). As used herein, chromite refers to chromium oxide, which includes all oxidation states of chromium oxide.

[0031] An impermeable layer or substance as used herein means that it is impermeable to fluid flow. For example, an impermeable layer or substance has a permeability less than 1 microdarcy or less than 1 nanodarcy.

[0032] In the present disclosure, sintering refers to the process of forming a solid mass of a material by heat or pressure or a combination thereof without melting the material to the extent of liquefaction. For example, the material particles are agglomerated into a solid or porous mass by heating, where the atoms in the material particles diffuse across the particle boundaries, causing the particles to fuse together and form a solid mass.

[0033] The term "in-situ" in the present disclosure refers to a process (e.g., heating or cracking) performed at the same location or in the same device. For example, ammonia cracking occurring in an anodic electrochemical reactor is considered to be in-situ.

[0034] Electrochemistry is a branch of physical chemistry that studies the relationship between electric potential (a measurable quantitative phenomenon) and identifiable chemical changes, where the electric potential is the result of a specific chemical change and vice versa. These reactions involve the movement of electrons between electrodes via an electronically conductive phase (usually, but not necessarily, an external circuit), separated by an ionically conductive and electronically insulating membrane (or ionic species in solution). When a chemical reaction is influenced by an electric potential difference, as in electrolysis, or if an electric potential is generated by a chemical reaction, as in a battery or fuel cell, it is called an electrochemical reaction. Different from chemical reactions, in electrochemical reactions, electrons (and necessarily the resulting ions) are not directly transferred between molecules, but rather via the above-mentioned electronically conductive and ionically conductive circuits accordingly. This phenomenon is the difference between electrochemical reactions and chemical reactions.

[0035] Regarding electrochemical reactors and methods of use, various components of the reactor, such as electrodes and membranes, as well as the materials that make up the components, are described. The following description lists various aspects and embodiments of the invention disclosed herein. No particular embodiment is intended to define the scope of the invention. Instead, the embodiments provide non-limiting examples of various compositions and methods included within the scope of the claimed invention. The description will be read from the perspective of a person of ordinary skill in the art. Thus, it does not necessarily include information known to a person of ordinary skill in the art.

[0036] Interconnects in electrochemical devices (e.g., fuel cells) are typically metallic or ceramic and are placed between individual cells or repeating units. Its purpose is to connect each cell or repeating unit so that electricity can be distributed or combined. In an electrochemical device, the interconnect is also referred to as a bipolar plate. As used herein, an interconnect as an impermeable layer means that it is a layer impermeable to fluid flow.

[0037] Electrochemical reactor

[0038] Contrary to conventional practice, an electrochemical reactor has been found that includes an ionically conductive membrane, where the reactor is capable of electrochemically reforming hydrocarbons or capable of electrochemically performing a water-gas shift reaction. Electrochemical reforming reactions involve the exchange of ions through the membrane to oxidize hydrocarbons. Electrochemical reactions involve the exchange of ions through the membrane and include a forward water-gas shift reaction or a reverse water-gas shift reaction or both. These are different from conventional reforming reactions and water-gas shift reactions via chemical routes because they involve the direct combination of reactants.

[0039] Figure 1AIllustrated is an electrochemical reactor or an electrochemical (EC) gas generator 100 according to an embodiment of the present disclosure. The electrochemical reactor (or EC gas generator) device 100 includes a first electrode 101, a membrane 103, and a second electrode 102. The first electrode 101 is configured to receive a fuel 104. For example, the stream 104 contains H2, ammonia, syngas, or a combination thereof. The stream 104 does not contain oxygen. The second electrode 102 is configured to receive a stream 105 containing carbon dioxide (CO2) and water (H2O).

[0040] In an embodiment, the device 100 is configured to receive CO2 and H2O at the second electrode (102) and generate CO and H2 contained in the stream 107. In some cases, the second electrode also receives a small amount of CO or H2, or both. Since CO2 and H2O provide the oxide ions (which are transported through the membrane) required to oxidize the fuel at the opposite electrode, CO2 and H2O are considered oxidants in this case. The reduction of CO2 produces CO. The reduction of H2O produces H2. Thus, the first electrode 101 undergoes an oxidation reaction in a reducing environment; the second electrode 102 undergoes a reduction reaction in a reducing environment. In some cases, this environment is considered a nominally reducing environment. In various embodiments, both electrodes are exposed to a reducing environment throughout the operating time.

[0041] In various embodiments, 103 represents an oxide ion conducting membrane. In an embodiment, the first electrode 101 and the second electrode 102 include Ni-YSZ or NiO-YSZ. In an embodiment, the oxide ion conducting membrane 103 also conducts electrons. In various embodiments, the electrodes 101 and 102 include Ni or NiO and a material selected from the group consisting of: YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof. Alternatively, the hydrocarbon-containing gas is reformed before contacting the membrane 103 / electrode 101. The reformer is configured to perform steam reforming, dry reforming, or a combination thereof. The reformed gas is suitable as the feed stream 104.

[0042] In an embodiment, the anode, cathode, and membrane have the same elements. For example, the anode, cathode, and membrane include Ni-YSZ. In an embodiment, the anode, cathode, and membrane include LaSrFeCr (lanthanum strontium iron-doped chromite) – SSZ (scandia-stabilized zirconia). In an embodiment, the anode, cathode, and membrane include LaSrFeCr-SCZ (Sc and Ce stabilized zirconia). In an embodiment, the anode, cathode, and membrane include LST (lanthanum-doped strontium titanate)-SCZ.

[0043] In the present disclosure, no oxygen means that there is no oxygen at the first electrode 101, or at least not enough oxygen to interfere with the reaction. Also, in the present disclosure, only water means that the intended feedstock is water, and trace elements or inherent components in the water are not excluded. For example, water containing salts or ions is considered to be within the scope of only water. Only water also does not require 100% pure water, but includes this embodiment.

[0044] In various embodiments, the device does not contain a current collector. In an embodiment, the device does not include interconnects. No electricity is required, and such a device is not an electrolyzer. This is a major advantage of the EC reactor of the present disclosure. The membrane 103 is configured to conduct electrons and is thus mixed-conducting, i.e., conducting both electrons and ions. In an embodiment, the membrane 103 conducts oxide ions and electrons. In an embodiment, the electrodes 101, 102, and the membrane 103 are tubular (e.g., see Figure 2A and Figure 2B ). In an embodiment, the electrodes 101, 102, and the membrane 103 are planar. In these embodiments, the electrochemical reaction at the electrodes is spontaneous and no potential / electricity needs to be applied to the reactor.

[0045] In an embodiment, an electrochemical reactor (or EC gas generator) is a device including a first electrode, a second electrode, and a membrane between the electrodes, wherein when the device is in use, the first electrode and the second electrode include a metal phase that does not contain platinum group metals, and wherein the membrane is oxide-ion-conducting. In an embodiment, the first electrode is configured to receive a fuel. In an embodiment, the fuel includes ammonia, syngas, hydrogen, methanol, carbon monoxide, or a combination thereof. In an embodiment, the second electrode is configured to receive CO2 and H2O (containing a small amount of CO or H2 or both), and is configured to reduce CO2 to CO and reduce H2O to H2. In various embodiments, this reduction occurs electrochemically.

[0046] Figure 1B An electrochemical reactor or electrochemical (EC) generator 100 for co-producing hydrogen and carbon monoxide according to an embodiment of the present disclosure is illustrated. The EC reactor 100 includes a first electrode 101, a membrane 103, and a second electrode 102. In various embodiments, the first electrode 101 is a metal or carbonate that is configured to carry, suspend, or circulate a feedstock 104 during reactor operation, wherein the metal or carbonate becomes liquid. The metals include tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), babbit metal, or a combination thereof. The carbonates include lithium carbonate, potassium carbonate, sodium carbonate, or a combination thereof.

[0047] The feedstock 104 includes carbon, ammonia, syngas, hydrogen, methanol, carbon monoxide, hydrocarbons, biodiesel, renewable natural gas, biogas, biomass, biowaste, charcoal, petroleum coke, edible oil, or combinations thereof. The carbon can be obtained from any source known to those skilled in the art, such as petroleum coke (coke or petroleum coke), carbon black, charcoal, graphite, coal, biowaste, biomass. Examples of hydrocarbons are methane, ethane, propane, butane. In various embodiments, the volume content of the solid feedstock (e.g., carbon) in the first electrode is not greater than 30 vol%. At the first electrode 101, the feedstock 104 is oxidized via oxide ions transported through the membrane 103. For example, carbon is converted to carbon monoxide or carbon dioxide (i.e., carbon oxides). The stream 106 represents the exhaust gas from the first electrode.

[0048] The second electrode 102 is configured to receive water (e.g., steam) and carbon dioxide, as represented by 105. In an embodiment, the stream 105 also contains hydrogen or carbon monoxide or both. At the second electrode 102, water is electrochemically reduced to hydrogen, and carbon dioxide is electrochemically reduced to carbon monoxide. The stream 107 represents the exhaust gas from the second electrode. Since water or carbon dioxide provides the oxide ions (which are transported through the membrane) required to oxidize the feedstock at the opposite electrode, water or carbon dioxide is considered an oxidizing agent in this case. Thus, the first electrode 101 undergoes an oxidation reaction in a reducing environment; the second electrode 102 undergoes a reduction reaction in a reducing environment. In an embodiment, the second electrode 102 includes Ni-YSZ or NiO-YSZ. In various embodiments, the electrode 102 includes Ni or NiO and a material selected from the group consisting of: YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof. In various embodiments, both electrodes are exposed to a reducing environment throughout the operating time.

[0049] In various embodiments, 103 represents an oxide ion conducting membrane. In an embodiment, the oxide ion conducting membrane 103 also conducts electrons. Thus, the reactor does not contain a current collector or interconnect. No electricity is required, and such a reactor is not an electrolyzer. This is the main advantage of the EC reactor of the present disclosure. The membrane 103 is configured to conduct electrons and is thus mixed conducting, i.e., conducting both electrons and ions. In an embodiment, the membrane 103 conducts oxide ions and electrons. In these embodiments, the electrochemical reactions at the anode and cathode are spontaneous and do not require an applied potential / electricity to the reactor.

[0050] In an embodiment, the membrane comprises an electronically conductive phase containing doped lanthanum chromite or an electronically conductive metal or a combination thereof; and wherein the membrane comprises an ion-conductive phase containing a material selected from the group consisting of gadolinium-doped ceria (CGO), samarium-doped ceria (SDC), yttria-stabilized zirconia (YSZ), lanthanum strontium gallium magnesium oxide (LSGM), scandia-stabilized zirconia (SSZ), Sc- and Ce-doped zirconia, cobalt-doped gadolinium-doped ceria (CoCGO), and combinations thereof. In an embodiment, the doped lanthanum chromite comprises strontium-doped lanthanum chromite, iron-doped lanthanum chromite, strontium- and iron-doped lanthanum chromite, lanthanum calcium chromite, or combinations thereof; and wherein the conductive metal comprises Ni, Cu, Ag, Au, Pt, Rh, or combinations thereof.

[0051] In one embodiment, the membrane comprises an electronically conductive phase and an ion-conductive phase. In some cases, the electronically conductive phase comprises doped lanthanum chromite or an electronically conductive metal or a combination thereof; and wherein the ion-conductive phase comprises a material selected from the group consisting of gadolinium- or samarium-doped ceria, yttria-stabilized zirconia (YSZ), lanthanum strontium gallium magnesium oxide (LSGM), scandia-stabilized zirconia (SSZ), Sc- and Ce-doped zirconia (SCZ), and combinations thereof. In an embodiment, the membrane comprises CoCGO or yttria-stabilized zirconia stabilized with LST (lanthanum-doped strontium titanate). In an embodiment, the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria-stabilized zirconia). In an embodiment, LST comprises LaSrCaTiO3. In an embodiment, the membrane comprises nickel-, copper-, cobalt-, or niobium-doped zirconia.

[0052] In an embodiment, the membrane comprises cobalt CGO (CoCGO), i.e., cobalt-doped CGO. In an embodiment, the membrane consists essentially of CoCGO. In an embodiment, the membrane consists of CoCGO. In an embodiment, the membrane comprises LST (lanthanum-doped strontium titanate)-YSZ or LST-SSZ or LST-SCZ (scandia-ceria-stabilized zirconia). In an embodiment, the membrane consists essentially of LST-YSZ or LST-SSZ or LST-SCZ. In an embodiment, the membrane consists of LST-YSZ or LST-SSZ or LST-SCZ. In the present disclosure, LST-YSZ refers to a composite of LST and YSZ. In various embodiments, the LST phase and the YSZ phase penetrate each other. In the present disclosure, LST-SSZ refers to a composite of LST and SSZ. In various embodiments, the LST phase and the SSZ phase penetrate each other. In the present disclosure, LST-SCZ refers to a composite of LST and SCZ. In various embodiments, the LST phase and the SCZ phase penetrate each other. YSZ, SSZ, and SCZ are types of stabilized zirconia.

[0053] Figure 2AIllustrated is a tubular electrochemical (EC) reactor or EC gas generator 200 (not drawn to scale) according to an embodiment of the present disclosure. The tubular generator 200 includes an inner tubular structure 202, an outer tubular structure 204, and a membrane 206 disposed therebetween, respectively, between the inner tubular structure 202 and the outer tubular structure 204. The tubular generator 200 further includes a void space 208 for a fluid passage. Figure 2B Illustrated is a cross-section of the tubular generator 200 (not drawn to scale) according to an embodiment of the present disclosure. The tubular generator 200 includes a first inner tubular structure 202, a second outer tubular structure 204, and a membrane 206 between the inner tubular structure 202 and the outer tubular structure 204. The tubular generator 200 further includes a void space 208 for a fluid passage.

[0054] In an embodiment, the electrodes and the membrane are tubular, where the first electrode is outermost and the second electrode is innermost, and where the second electrode is configured to receive H2O and CO2. In an embodiment, the electrodes and the membrane are tubular, where the first electrode is innermost and the second electrode is outermost, and where the second electrode is configured to receive H2O and CO2. In an embodiment, the electrodes and the membrane are planar.

[0055] The electrochemical reactions occurring in the reactor include electrochemical half-cell reactions. In various embodiments, the half-cell reactions occur at a triple-phase boundary, where the triple-phase boundary is the intersection of a pore with an electron-conducting phase and an ion-conducting phase.

[0056] In various embodiments, the ion-conducting membrane conducts protons or oxide ions. In various embodiments, the ion-conducting membrane includes solid oxides. In various embodiments, the ion-conducting membrane is impermeable to fluid flow. In various embodiments, the ion-conducting membrane also conducts electrons and where the reactor does not include interconnects.

[0057] Electrochemical co-production of H2 and CO

[0058] The EC reactor as described above is adapted to simultaneously electrochemically produce CO from CO2 and H2 from H2O at the cathode side. In an embodiment, the reactor includes a porous electrode that includes a metal phase and a ceramic phase, where the metal phase is electron-conducting and where the ceramic phase is ion-conducting. In various embodiments, the electrodes are not attached to their current collectors. In various embodiments, the reactor does not contain any current collectors or interconnects. Obviously, such a reactor is fundamentally different from any electrolysis device or any fuel cell.

[0059] As Figure 3As shown, a co-production system (300) of CO and H2 is shown. System 300 includes an EC reactor 331, a fuel source 311, a carbon dioxide and water source 321, and a separator 341. 301 represents the anode in the reactor, and 302 represents the cathode in the reactor. 303 represents the membrane between the electrodes in the reactor. A first stream 392 containing fuel passes through the anode 301, is oxidized, and leaves the anode as stream 393. A second stream 394 from source 321 passes through the cathode 302, where CO2 is reduced to CO and H2O is reduced to H2. The cathode exhaust stream 395 passes through the separator 341, where CO is separated from CO2 and H2 is separated from H2O. The product stream 396 leaves the separator 341 and consists essentially of CO and H2. A portion of stream 395 or stream 396 may be recycled to the cathode 302 ( Figure 3 not shown in). In various embodiments, the cathode receives hydrogen or carbon monoxide in addition to steam and carbon dioxide to ensure a true reducing environment throughout the operation of the reactor. In various embodiments, both electrodes are exposed to a reducing environment throughout the operating time.

[0060] The method and system for co-producing CO and H2 according to the present disclosure have various advantages. Generating CO from CO2 is desirable because it reduces greenhouse gas emissions. Producing CO and H2 locally (on-site) is inherently safer than transporting CO and H2 in pressurized containers or vessels. The method of the present disclosure utilizes an efficient electrochemical pathway but does not require electricity. Separating CO / CO2 and H2 / H2O from the cathode exhaust is both simple and inexpensive. Thus, the method and system of the present disclosure are cost-competitive in both capital equipment and operating expenses.

[0061] In various embodiments, the ratio of H2 / CO co-production is controlled by changing the input ratio of H2O / CO2, by changing the operating temperature, by changing the fuel composition, or a combination thereof. Thus, the product from the separator is suitable for various downstream chemical production without further purification or modification. This is another major advantage of the method and system of the present disclosure.

[0062] Production of valuable products

[0063] The production system 300 may further include a chemical generator ( Figure 3(not shown in the figure), which is selected from the group consisting of: Fischer-Tropsch synthesis reactor, methanol generator, ethanol generator, hydrocarbon generator, plastic monomer generator, and combinations thereof. The Fischer-Tropsch synthesis reactor is capable of generating valuable products such as naphtha, gasoline, diesel, wax. The produced methanol can be further converted into gasoline, ethylene, acetic acid, formaldehyde, methyl acetate, polyolefins, dimethyl ether (DME), or combinations thereof. In various embodiments, the chemical generator is configured to receive carbon monoxide and hydrogen from a separator. Additionally, the system may include a polymerization unit to convert plastic monomers into various types of plastics. The configurations and arrangements for utilizing the produced CO and H2 are known to those skilled in the art, and all such configurations and arrangements are within the scope of the present disclosure.

[0064] It should be understood that the present disclosure describes exemplary embodiments for implementing different features, structures, or functions of the present invention. To simplify the present disclosure, exemplary embodiments of components, arrangements, and configurations are described; however, these exemplary embodiments are provided only as examples and are not intended to limit the scope of the present invention. Unless otherwise specified, the embodiments given herein can be combined. Such combinations do not depart from the scope of the present disclosure.

[0065] Additionally, certain terms are used throughout the description and claims to refer to specific components or steps. As understood by those skilled in the art, various entities can refer to the same component or process step by different names, and thus, the naming convention of the elements described herein is not intended to limit the scope of the present invention. Furthermore, the terms and naming convention used herein are not intended to distinguish components, features, and / or steps that have different names but the same function.

[0066] Although the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and description. However, it should be understood that the drawings and the detailed description are not intended to limit the present disclosure to the particular forms disclosed, but rather, the present invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

Claims

1. A method for co-producing carbon monoxide and hydrogen, the method comprising: (a) Provide an electrochemical reactor having an anode, a cathode, and a mixed conducting membrane located between the anode and the cathode; (b) Introduce a first stream into the anode, wherein the first stream contains fuel; (c) Introduce a second stream into the cathode, wherein the second stream contains carbon dioxide and water, wherein carbon monoxide is electrochemically generated from carbon dioxide, and hydrogen is electrochemically generated from water.

2. The method according to claim 1, wherein the anode and the cathode are separated by the membrane, and both are exposed to a reducing environment during the entire operation time.

3. The method according to claim 1, wherein the cathode comprises Ni or NiO and a material selected from the group consisting of: YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof.

4. The method according to claim 1, wherein the anode, the cathode, and the membrane have the same elements.

5. The method according to claim 4, wherein the anode, the cathode, and the membrane comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST-SCZ.

6. The method according to claim 1, wherein the anode comprises Ni or NiO and a material selected from the group consisting of: YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof.

7. The method according to claim 6, wherein the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, or combinations thereof.

8. The method according to claim 1, wherein the anode is liquid during operation; wherein the anode comprises tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), babbitt alloy, or combinations thereof, or wherein the anode comprises lithium carbonate, potassium carbonate, sodium carbonate, or combinations thereof.

9. The method according to claim 8, wherein the fuel comprises carbon, ammonia, syngas, hydrogen, methanol, carbon monoxide, hydrocarbons, biodiesel, renewable natural gas, biogas, biomass, bio-waste, charcoal, petroleum coke, edible oil, or combinations thereof.

10. The method according to claim 1, wherein the anode comprises doped or undoped cerium dioxide and a material selected from the group consisting of: Cu, CuO, Cu2O, Ag, Ag2O, Au, Au2O, Au2O3, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, stainless steel, and combinations thereof.

11. The method according to claim 10, wherein the fuel comprises hydrocarbons.

12. The method according to claim 1, wherein the membrane comprises an electron-conducting phase and an ion-conducting phase.

13. The method according to claim 12, wherein the electronically conductive phase comprises doped lanthanum chromite or an electronically conductive metal or a combination thereof; and wherein the ionically conductive phase comprises a material selected from the group consisting of gadolinium- or samarium-doped ceria, yttria-stabilized zirconia (YSZ), lanthanum strontium gallium magnesium oxide (LSGM), scandia-stabilized zirconia (SSZ), Sc- and Ce-doped zirconia (SCZ), and combinations thereof.

14. The method according to claim 1, wherein the membrane comprises CoCGO or zirconia stabilized by LST (lanthanum-doped strontium titanate).

15. The method according to claim 14, wherein the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria stabilized zirconia), and wherein the LST comprises LaSrCaTiO3.

16. The method according to claim 1, wherein the membrane comprises nickel-, copper-, cobalt-, or niobium-doped zirconia.

17. The method according to claim 1, wherein cathode exhaust is passed through a separator, and wherein the generated carbon monoxide and hydrogen are separated from the exhaust.

18. The method according to claim 17, which comprises using the separated CO and H2 to produce methanol, ethanol, hydrocarbons, plastic monomers, polyethylene, or combinations thereof.

19. The method according to claim 1, wherein the reactor does not include an interconnect and does not include a current collector.

20. The method according to claim 1, wherein the reactor does not generate electricity and does not receive electricity.

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