Electrochemical generator for hydrogen or carbon monoxide

Abstract

Contemplated herein is an electrochemical reactor comprising a first electrode, the first electrode being a liquid when the reactor is in operation, a second electrode having a metal phase and a ceramic phase, the metal phase being electronically conductive and the ceramic phase being ionically conductive, and a membrane, the membrane being positioned between and in contact with the first and second electrodes, the membrane being mixed conducting. Also contemplated herein is a method of producing hydrogen or carbon monoxide comprising: (a) providing an electrochemical reactor having an anode, a cathode, and a membrane between the anode and the cathode, the anode being a liquid when the reactor is in operation and the membrane being mixed conducting; (b) introducing a feedstock to the anode; and (c) introducing a stream to the cathode, the stream comprising water or carbon dioxide.

Description

[Technical field]

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

[0002] Carbon monoxide (CO) is a colorless, odorless, tasteless, and flammable gas that is slightly less dense than air. It is well known for its toxic effects, as it easily combines with hemoglobin to produce carboxyhemoglobin, which is highly toxic above certain concentrations. However, CO is an important component in many chemical and industrial processes. CO has a wide range of functions across all areas of chemistry, for example, metal-carbonyl catalysis, radical chemistry, and cation and anion chemistry. Carbon monoxide is a strong reducing agent and has been used in pyrometallurgy for centuries to reduce metals from their ores. As an example for making 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 in upgrading fossil fuels and in the production of methanol or hydrochloric acid. Petrochemical plants require hydrogen for hydrocracking, hydrodesulfurization, and hydrodealkylation. Hydrogenation processes to increase the saturation levels of unsaturated fats and oils also require hydrogen. Hydrogen is also a reducing agent for metal ores. Hydrogen can be produced from electrolysis of water, steam reforming, laboratory-scale metal acid processes, thermochemical methods, or anaerobic corrosion. Many countries are aiming for a hydrogen economy.

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

[0005] Clearly, there is an increasing need and interest to develop new technology platforms for producing these building blocks and valuable products. The present disclosure contemplates the production of valuable products via an efficient electrochemical route. Furthermore, the methods and systems disclosed herein do not require extensive and expensive separation and purification processes as required in the prior art. Summary of the Invention

[0006] Contemplated herein is an electrochemical reactor comprising a first electrode, the first electrode being liquid when the reactor is in operation, a second electrode having a metallic phase and a ceramic phase, the metallic phase being electronically conductive and the ceramic phase being ionically conductive, and a membrane, the membrane positioned between and in contact with the first and second electrodes, the membrane being mixed conductive.

[0007] In one embodiment, the second electrode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof. In one embodiment, the second electrode is porous. In one embodiment, the second electrode is configured to electrochemically reduce water to hydrogen or to electrochemically reduce carbon dioxide to carbon monoxide. In one embodiment, the first electrode comprises tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), Babbitt metal, or combinations thereof. In one embodiment, the first electrode comprises lithium carbonate, potassium carbonate, sodium carbonate, or combinations thereof. In one embodiment, the first electrode is configured to transport a feedstock.

[0008] In one embodiment, the feedstock comprises carbon, ammonia, syngas, hydrogen, methanol, carbon monoxide, hydrocarbons, biodiesel, renewable natural gas, biogas, biomass, biowaste, charcoal, petcoke, cooking oil, or combinations thereof. In one embodiment, the first electrode is configured to electrochemically oxidize the feedstock. In one embodiment, the reactor does not include an interconnect and a current collector. In one embodiment, the reactor does not generate electricity and does not accept electricity.

[0009] In one embodiment, the membrane comprises an electronically conductive phase and an ionically conductive phase, in one embodiment, the electronically conductive phase comprises doped lanthanum chromite or an electronically conductive metal, or a combination thereof, and the ionically conductive phase comprises a material selected from the group consisting of gadolinium or samarium doped ceria, yttria stabilized zirconia (YSZ), lanthanum strontium gallate magnesite (LSGM), scandia stabilized zirconia (SSZ), Sc and Ce doped zirconia (SCZ), and combinations thereof.

[0010] In one embodiment, the film comprises CoCGO or LST (lanthanum doped strontium titanate) stabilized zirconia. In one embodiment, the stabilized zirconia comprises YSZ or SSZ or SCZ (scan diaceria stabilized zirconia), and LST comprises LaSrCaTiO3. In one embodiment, the film comprises nickel, copper, cobalt, or niobium doped zirconia.

[0011] Also contemplated herein is a method for producing hydrogen or carbon monoxide, comprising: (a) providing an electrochemical reactor having an anode, a cathode, and a membrane between the anode and the cathode, the anode being liquid when the reactor is in operation and the membrane being mixed conducting; (b) introducing a feedstock to the anode; and (c) introducing a stream to the cathode, the stream including water or carbon dioxide. In one embodiment, both the anode and the cathode are exposed to a reducing environment during the entire operation. In one embodiment, the anode comprises tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), Babbitt metal, or a combination thereof. In one embodiment, the anode comprises lithium carbonate, potassium carbonate, sodium carbonate, or a combination thereof.

[0012] Further aspects and embodiments are provided in the following drawings, detailed description, and claims. Unless otherwise specified, features described herein can be combined, and all such combinations are within the scope of the disclosure.

[0013] The following drawings are provided to illustrate certain embodiments described herein. The drawings are merely exemplary and are not intended to limit the scope of the claimed invention, nor are they intended to show every possible feature or embodiment of the claimed invention. The drawings are not necessarily drawn to scale, and in some instances, certain elements of the drawings may be enlarged relative to other elements of the drawings for illustrative purposes. [Brief description of the drawings]

[0014] [Figure 1] 1 illustrates an electrochemical (EC) reactor or electrochemical generator for producing H2 or CO, according to one embodiment of the present disclosure. [Diagram 2] 1 illustrates a tubular configuration for an electrochemical reactor or generator according to one embodiment of the present disclosure. [Diagram 3] 1 illustrates a production system having multiple electrochemical reactor tubes, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] overview Unless otherwise defined herein, the following terms and phrases have the meanings set forth below. This disclosure may use other terms and phrases not expressly defined herein. Such other terms and phrases shall have the meanings they would have within the context of this disclosure to one of ordinary skill in the art. In some cases, a term or phrase may be defined in the singular or plural. In such instances, it is understood that any term in the singular may include its plural counterpart, and vice versa, unless expressly indicated to the contrary.

[0016] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to a "substituent" includes a single substituent, as well as two or more substituents, and so forth. As used herein, "for example," "for instance," "such as," or "including" are meant to introduce examples that further clarify a more general subject matter. Unless expressly indicated otherwise, these examples are provided only as an aid to understanding the embodiments illustrated in this disclosure and are not intended to be limiting in any way. Additionally, these phrases do not indicate any kind of preference to the disclosed embodiments.

[0017] As used herein, compositions and materials are used interchangeably unless otherwise specified. Each composition / material may have multiple elements, phases, and components. As used herein, heating refers to the active addition of energy to a composition or material.

[0018] As used herein, YSZ refers to yttria stabilized zirconia, SDC refers to samaria doped ceria, SSZ refers to scandia stabilized zirconia, and LSGM refers to lanthanum strontium gallate magnesite.

[0019] In this disclosure, the absence of substantial amounts of H2 means that the volumetric content of hydrogen is 5% or less, or 3% or less, or 2% or less, or 1% or less, or 0.5% or less, or 0.1% or less, or 0.05% or less.

[0020] As used herein, CGO refers to gadolinium-doped ceria, alternatively known as gadolinia-doped ceria, gadolinium-doped cerium oxide, cerium (IV) oxide, gadolinium-doped, GDC or GCO (formula Gd:CeO2). Unless otherwise specified, CGO and GDC are used interchangeably. Syngas (i.e., synthesis gas) in this disclosure refers to a mixture consisting primarily of hydrogen, carbon monoxide, and carbon dioxide.

[0021] Mixed conducting membranes can transport both electrons and ions. Ionic conductivity includes ionic species such as oxygen ions (or oxide ions), protons, halide anions, chalcogenide anions, etc. In various embodiments, the mixed conducting membranes of the present disclosure include an electronically conducting phase and an ionically conducting phase.

[0022] In this disclosure, the axial cross-section of the tubular portion is shown to be circular, but this is by way of example and not limitation, the axial cross-section of the tubular portion may be any suitable shape, such as a square, a square with rounded corners, a rectangle, a rectangle with rounded corners, a triangle, a hexagon, a pentagon, an ellipse, an irregular shape, etc., as known to those skilled in the art.

[0023] 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 samaria-doped ceria (SDC) or gadolinium-doped ceria (GDC or CGO). As used herein, chromite refers to chromium oxide, including all oxidation states of chromium oxide.

[0024] As used herein, a layer or material that is impermeable refers to one that is impermeable to the flow of fluids. For example, an impermeable layer or material has a permeability of less than 1 microdarcy, or less than 1 nanodarcy.

[0025] In this disclosure, sintering refers to a process for forming a solid mass of a material by heat or pressure, or a combination thereof, without melting the material to the extent that it becomes liquid. For example, material particles are heated to coalesce into a solid or porous mass, and atoms within the material particles diffuse across the boundaries of the particles, fusing the particles together to form one solid piece.

[0026] The term "in situ" in this disclosure refers to a treatment (e.g., heating or decomposition) process that is carried out either at the same location or within the same device. For example, ammonia decomposition that occurs within an electrochemical reactor at the anode is considered in situ.

[0027] Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential as a measurable and quantitative phenomenon and an identifiable chemical change, where the electrical potential is either the result of a particular chemical change or vice versa. These reactions involve electrons moving between electrodes through electronically conducting phases (typically, but not necessarily, an external electric circuit) separated by ionically conducting and electronically insulating membranes (or ionic species in solution). When a chemical reaction is influenced by a potential difference, such as during electrolysis, or when an electrical potential arises from a chemical reaction such as in a battery or fuel cell, it is called an electrochemical reaction. Unlike chemical reactions, in electrochemical reactions, electrons (and the resulting ions) are not transferred directly between molecules, but through the aforementioned electronically and ionically conducting circuits, respectively. This phenomenon distinguishes electrochemical reactions from chemical reactions.

[0028] In connection with the electrochemical reactor and method of use, various components of the reactor, such as electrodes and membranes, are described, along with the materials of construction of the components. The following description details various aspects and embodiments of the invention disclosed herein. The specific embodiments are not intended to define the scope of the invention. Rather, the embodiments provide non-limiting examples of various compositions and methods that fall within the scope of the claimed invention. This description should be read from the perspective of one skilled in the art. Thus, information known to one skilled in the art is not necessarily included.

[0029] Interconnects in electrochemical devices (e.g., fuel cells) are often either metal or ceramic placed between individual cells or repeating units. Their purpose is to connect each cell or repeating unit so that electricity can be distributed or combined. Interconnects are also referred to as bipolar plates in electrochemical devices. As used herein, an interconnect that is an impermeable layer refers to a layer that is impermeable to fluid flow.

[0030] In this disclosure, biomass is plant or animal material that is oxidized and used as fuel. Examples of biomass are wood, grass, sugarcane, rice, energy crops, and waste from forests, gardens, or farms.

[0031] Electrochemical Reactors Contrary to the conventional practice, an electrochemical reactor has been found that includes a mixed conducting membrane, which can electrochemically produce hydrogen from water without electrical input. The reactor can also electrochemically produce carbon monoxide from carbon dioxide without electrical input. The electrochemical reaction involves the exchange of oxide ions through the membrane to oxidize the fuel (e.g., carbon). The mixed conducting membrane also conducts electrons to complete the electrochemical reaction. Thus, the reactor does not include interconnects or bipolar plates. Additionally, the reactor does not generate electricity and is not a fuel cell. In various embodiments, the electrodes do not have current collectors attached to them. In various embodiments, the reactor does not contain any current collectors. Clearly, such a reactor is fundamentally different from any electrolysis device or any fuel cell.

[0032] The electrochemical reaction occurring in the reactor comprises an electrochemical half-cell reaction. In various embodiments, the half-cell reaction takes place at a three-phase boundary, the three-phase boundary being the intersection of the electronically and ionically conductive phases with the pores. In various embodiments, the membrane is impermeable to fluid flow. In one embodiment, the reactor comprises a porous electrode comprising a metal phase and a ceramic phase, the metal phase being electronically conductive and the ceramic phase being ionically conductive.

[0033] FIG. 1 illustrates an electrochemical reactor or electrochemical (EC) generator 100 for hydrogen production according to one embodiment of the disclosure. The EC reactor 100 comprises a first electrode 101, a membrane 103, and a second electrode 102. In various embodiments, the first electrode 101 is a metal or carbonate configured to carry, suspend, or circulate a feedstock 104 when the reactor is in operation, the metal or carbonate being liquid. The metal includes tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), Babbitt metal, or a combination thereof. The carbonate includes lithium carbonate, potassium carbonate, sodium carbonate, or a combination thereof.

[0034] The feedstock 104 includes carbon, ammonia, syngas, hydrogen, methanol, carbon monoxide, hydrocarbons, biodiesel, renewable natural gas, biogas, biomass, biowaste, charcoal, petcoke, cooking oil, or combinations thereof. Carbon can be obtained from any source known to those skilled in the art, such as petroleum coke (coke or petcoke), carbon black, char, graphite, coal, biowaste, biomass, etc. Examples of hydrocarbons are methane, ethane, propane, butane. In various embodiments, the volume content of solid feedstock (e.g., carbon) in the first electrode is 30% by volume or less. 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). Stream 106 represents the exhaust from the first electrode.

[0035] The second electrode 102 is configured to receive water (e.g., steam), as shown at 105. In one embodiment, stream 105 also contains hydrogen, but the amount of hydrogen is less than water. At the second electrode 102, the water is electrochemically reduced to hydrogen. Stream 107 represents the exhaust from the second electrode. Water is considered the oxidant in this scenario because it provides the oxide ions (transported through the membrane) necessary to oxidize the feedstock at the opposite electrode. Thus, the first electrode 101 is performing an oxidation reaction in a reducing environment, and the second 102 electrode is performing a reduction reaction in a reducing environment. In one embodiment, the second electrode 102 comprises Ni-YSZ or NiO-YSZ. In various embodiments, the electrode 102 comprises 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 the reducing environment during the entire time of operation.

[0036] In embodiments where CO is produced, the second electrode 102 is configured to receive carbon dioxide (CO2), as shown at 105. In some cases, the second electrode also receives a small amount of CO. In this scenario, CO2 is considered the oxidant, since it provides the oxide ions (transported through the membrane) necessary to oxidize the fuel at the opposite electrode. Reduction of CO2 produces CO. Thus, the first electrode 101 is performing an oxidation reaction in a reducing environment, and the second electrode 102 is performing a reduction reaction in a reducing environment. In some cases, such an environment is nominally considered a reducing environment. In various embodiments, both electrodes are exposed to the reducing environment during the entire time of operation.

[0037] In various embodiments, 103 represents an oxide ion conducting membrane. In one embodiment, the oxide ion conducting membrane 103 also conducts electrons. Thus, the reactor does not contain current collectors or interconnects. No electricity is required and such reactors are not electrolyzers. This is a major advantage of the EC reactors of the present disclosure. The membrane 103 is configured to conduct electrons and is therefore mixed conducting, i.e., both electronically and ionically conducting. In one embodiment, the membrane 103 conducts oxide ions and electrons. In these embodiments, the electrochemical reactions at the anode and cathode are spontaneous without the need to apply a potential / electricity to the reactor.

[0038] In one embodiment, the membrane 103 includes an electronically conductive phase containing doped lanthanum chromite, or an electronically conductive metal, or a combination thereof, and the membrane includes an ionically 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 gallate magnesite (LSGM), scandia stabilized zirconia (SSZ), Sc and Ce doped zirconia, cobalt doped gadolinium doped ceria (CoCGO), and combinations thereof. In one embodiment, the doped lanthanum chromite includes strontium doped lanthanum chromite, iron doped lanthanum chromite, strontium and iron doped lanthanum chromite, lanthanum calcium chromite, or a combination thereof, and the conductive metal includes Ni, Cu, Ag, Au, Pt, Rh, Co, or a combination thereof. In one embodiment, the film 103 comprises gadolinium doped ceria, samarium doped ceria, a sintering aid, or a combination thereof. In one embodiment, the film comprises CoCGO. In one embodiment, the film consists of CoCGO. In one embodiment, the sintering aid comprises a divalent or trivalent transition metal ion, or a combination thereof. In one embodiment, the transition metal comprises Co, Mn, Fe, Cu, or a combination thereof.

[0039] In one embodiment, the membrane comprises an electronically conductive phase and an ionically conductive phase. In some cases, the electronically conductive phase comprises doped lanthanum chromite, or an electronically conductive metal, or a combination thereof, and the ionically conductive phase comprises a material selected from the group consisting of gadolinium or samarium doped ceria, yttria stabilized zirconia (YSZ), lanthanum strontium gallate magnesite (LSGM), scandia stabilized zirconia (SSZ), Sc and Ce doped zirconia (SCZ), and combinations thereof. In one embodiment, the membrane comprises CoCGO or LST (lanthanum doped strontium titanate) stabilized zirconia. In one embodiment, the stabilized zirconia comprises YSZ or SSZ or SCZ (scandiaceria stabilized zirconia). In one embodiment, the LST comprises LaSrCaTiO3. In one embodiment, the membrane comprises nickel, copper, cobalt, or niobium doped zirconia.

[0040] In one embodiment, the membrane comprises cobalt-CGO (CoCGO), i.e., cobalt-doped CGO. In one embodiment, the membrane consists essentially of CoCGO. In one embodiment, the membrane consists of CoCGO. In one embodiment, the membrane comprises LST (lanthanum doped strontium titanate)-YSZ, or LST-SSZ, or LST-SCZ (scandiaceria stabilized zirconia). In one embodiment, the membrane consists essentially of LST-YSZ, or LST-SSZ, or LST-SCZ. In one embodiment, the membrane consists of LST-YSZ, or LST-SSZ, or LST-SCZ. In this disclosure, LST-YSZ refers to a composite of LST and YSZ. In various embodiments, the LST and YSZ phases interpenetrate. In this disclosure, LST-SSZ refers to a composite of LST and SSZ. In various embodiments, the LST and SSZ phases interpenetrate. In this disclosure, LST-SCZ refers to a composite of LST and SCZ. In various embodiments, the LST and SCZ phases interpenetrate each other. YSZ, SSZ, and SCZ are types of stabilized zirconia.

[0041] In one embodiment, the EC reactor 100 is configured to simultaneously produce H2 or CO (in stream 107) from the second electrode 102 and carbon dioxide (in stream 106) from the first electrode 101. The produced carbon dioxide (or stream 106) is sent to a carbon capture unit for sequestration. In one embodiment, the electrodes 102 and membrane 103 are tubular (see, e.g., FIG. 2). In one embodiment, the electrodes 102 and membrane 103 are planar.

[0042] Electrochemical generation of H2 or CO FIG. 2 illustrates a tubular configuration of an electrochemical (EC) reactor or EC generator 200 (not to scale) according to one embodiment of the present disclosure. The reactor or generator 200 comprises an inner tubular structure (inner tube) 202 as an electrode, in this case the cathode. In various embodiments, the inner tube (cathode) is porous. The reactor or generator 200 also comprises an outer tubular structure (outer tube) 203, which is a mixed conducting membrane. In various embodiments, the membrane is impermeable to fluid flow. The inner tube 202 and the outer tube 203 are in contact with each other and are immersed in a liquid 201, which is the anode to the reactor or generator 200. A feedstock 204 is carried in the liquid 201.

[0043] Stream 205 represents water (or steam) with a small amount of hydrogen that is introduced into inner tube 202 for hydrogen production. In the case of CO production, 205 represents a CO2-containing stream, and in some cases also contains some amount of CO. The cathode exhaust is represented by stream 207, which contains electrochemically produced H2 or CO. Stream 207 may be sent to a separator where hydrogen is separated from water or carbon monoxide is separated from carbon dioxide. Stream 206 represents the anode exhaust. In embodiments where carbon is the feedstock, the carbon dioxide in stream 206 is of sufficient purity to be directly sequestered or utilized (e.g., injected into a well) without further separation or purification.

[0044] In one embodiment, the reactor is operated at a temperature in the range of 600° C. to 1000° C. In one embodiment, the reactor is operated at a temperature in the range of 600° C. to 900° C. In one embodiment, the reactor is operated at a temperature in the range of 600° C. to 800° C.

[0045] As illustrated in FIG. 3, an H2 or CO generating system is shown with multiple reactor tubes according to one embodiment of the disclosure. In some cases, the reactor tubes are connected in series for cathode input and output. In some cases, the reactor tubes are connected in parallel for cathode input and output. All suitable configurations and arrangements are contemplated and are within the scope of the present disclosure. The cross-section of the reactor tubes can be any suitable shape and is not limited by those illustrated in FIG. 2 and FIG. 3.

[0046] advantage The disclosed H2 or CO production process and system has various advantages. The disclosed process utilizes an efficient electrochemical pathway, yet does not require electricity. Thus, implementation of the process can be in remote locations without grid power supply. Separation of hydrogen from water in the cathode exhaust is easy and inexpensive. Separation of carbon monoxide from carbon dioxide in the cathode exhaust is also easy and inexpensive. Thus, the disclosed method and system is cost-competitive in both capital equipment and operational costs. The generated H2 or CO, or both, can be further utilized to produce valuable products such as methanol, ethanol, hydrocarbons, plastic monomers, polyethylene, or combinations thereof.

[0047] In addition, the production of H2 or CO from feedstocks such as those discussed herein as fuels is desirable because such fuel sources are abundant and inexpensive. The carbon dioxide produced when carbon is utilized is of high purity and easily sequestered, thus reducing greenhouse gas emissions. Furthermore, the energy and steel industries currently send waste around the world to be burned into CO2 and released into the atmosphere. The disclosed method and system allows for the capture of carbon from waste streams that would otherwise be released into the environment, while simultaneously producing clean and pure H2 or CO, or both. For example, carbon-containing solid waste can be transported to a wellhead and converted to carbon dioxide on-site for direct injection, while H2 or CO, or both, are simultaneously produced for clean energy consumers or valuable chemical production.

[0048] It is to be understood that the present disclosure describes exemplary embodiments for implementing different features, structures, or functions of the present invention. Although exemplary embodiments of components, arrangements, and configurations are described to simplify the present disclosure, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the present invention. The embodiments as presented herein may be combined unless otherwise specified. Such combinations do not depart from the scope of the present disclosure.

[0049] Additionally, certain terms are used throughout the description and claims to refer to particular components or steps. As one skilled in the art will appreciate, various entities may refer to the same component or process step by different names, and therefore, the naming conventions for elements described herein are not intended to limit the scope of the invention. Moreover, the terminology and naming conventions used herein are not intended to distinguish between components, features, and / or steps that differ in name but not function.

[0050] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and description, it should be understood, however, that the drawings and detailed description are not intended to limit the disclosure to the particular forms disclosed, but on the contrary, are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

Claims

1. 1. An electrochemical reactor comprising: a first electrode, the first electrode being liquid when the reactor is in operation; a second electrode having a metallic phase and a ceramic phase, the metallic phase being electronically conductive and the ceramic phase being ionically conductive; and a membrane, the membrane positioned between and in contact with the first and second electrodes, the membrane being mixed conductive.

2. 10. The reactor of claim 1, wherein the second electrode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof.

3. 10. The reactor of claim 1 wherein the second electrode is porous.

4. 10. The reactor of claim 1, wherein the second electrode is configured to electrochemically reduce water to hydrogen or to electrochemically reduce carbon dioxide to carbon monoxide.

5. 10. The reactor of claim 1, wherein the first electrode comprises tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), Babbitt metal, or a combination thereof.

6. 10. The reactor of claim 1, wherein the first electrode comprises lithium carbonate, potassium carbonate, sodium carbonate, or a combination thereof.

7. 10. The reactor of claim 1, wherein the first electrode is configured to convey a feedstock.

8. 8. The reactor of claim 7, wherein the feedstock comprises carbon, ammonia, syngas, hydrogen, methanol, carbon monoxide, hydrocarbons, biodiesel, renewable natural gas, biogas, biomass, biowaste, charcoal, petcoke, cooking oil, or combinations thereof.

9. 10. The reactor of claim 1, wherein the first electrode is configured to electrochemically oxidize a feedstock.

10. 10. The reactor of claim 1 , which is free of interconnects and current collectors.

11. 10. The reactor of claim 1 which does not produce electricity and does not accept electricity.

12. 10. The reactor of claim 1, wherein the membrane comprises an electronically conductive phase and an ionically conductive phase.

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

14. 10. The reactor of claim 1, wherein the membrane comprises CoCGO or LST (lanthanum doped strontium titanate) stabilized zirconia.

15. The stabilized zirconia includes YSZ, SSZ, or SCZ (scandiaceria stabilized zirconia), and the LST includes LaSrCaTiO ３ The reactor of claim 14 comprising:

16. 10. The reactor of claim 1, wherein the membrane comprises nickel, copper, cobalt, or niobium doped zirconia.

17. 1. A method for producing hydrogen or carbon monoxide, comprising: (a) providing an electrochemical reactor having an anode, a cathode, and a membrane between the anode and the cathode, the anode being liquid when the reactor is in operation and the membrane being mixed conducting; (b) introducing a feedstock to the anode; and (c) introducing a stream to the cathode, the stream comprising water or carbon dioxide.

18. 20. The method of claim 17, wherein both the anode and the cathode are exposed to a reducing environment during the entire operation.

19. 18. The method of claim 17, wherein the anode comprises tin (Sn), bismuth (Bi), cadmium (Cd), lead (Pb), antimony (Sb), indium (In), silver (Ag), Babbitt metal, or a combination thereof.

20. 18. The method of claim 17, wherein the anode comprises lithium carbonate, potassium carbonate, sodium carbonate, or a combination thereof.

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