WO2025048953A1

WO2025048953A1 - Counter flow electrochemical reactor and method of use

Info

Publication number: WO2025048953A1
Application number: PCT/US2024/036531
Authority: WO
Inventors: Matthew Dawson
Original assignee: Utility Global Inc
Current assignee: Utility Global Inc
Priority date: 2023-08-28
Filing date: 2024-07-02
Publication date: 2025-03-06
Anticipated expiration: 2026-02-28

Abstract

Herein discussed is a method of producing hydrogen or carbon monoxide or both comprising: (a) providing an electrochemical reactor comprising an anode, a cathode, and a mixed-conducting electrolyte between the anode and the cathode, (b) introducing a first fluid to the anode, wherein the first fluid provides a reducing atmosphere for the anode, and (c) introducing a second fluid to the cathode, wherein the second fluid provides a reducing atmosphere for the cathode, wherein the direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, and wherein the direction of the bulk flow of the first fluid changes in the reactor.

Description

Counter Flow Electrochemical Reactor and Method of Use

TECHNICAL FIELD

[1] This invention generally relates to electrochemical reactors. More specifically, this invention relates to counter flow electrochemical reactors and method of use.

BACKGROUND

[2] Carbon monoxide (CO) is a colorless, odorless, tasteless, and flammable gas that is slightly less dense than air. It is well known for its poisoning effect because CO readily combines with hemoglobin to produce carboxyhemoglobin, which is highly toxic when the concentration exceeds a certain level. However, CO is a key ingredient in many chemical and industrial processes. CO has a wide range of functions across all disciplines of chemistry, e.g., metal-carbonyl catalysis, radical chemistry, cation and anion chemistries. Carbon monoxide is a strong reductive agent and has been used in pyrometallurgy to reduce metals from ores for centuries. As an example for making specialty compounds, CO is used in the production of vitamin A.

[3] Hydrogen (H2) in large quantities is needed in the petroleum and chemical industries. For example, large amounts of hydrogen are used in upgrading fossil fuels and in the production of methanol or hydrochloric acid. Petrochemical plants need hydrogen for hydrocracking, hydrodesulfurization, hydrodealkylation. Hydrogenation processes to increase the level of saturation of unsaturated fats and oils also need hydrogen. Hydrogen is also a reducing agent of metallic ores. Hydrogen may be produced from electrolysis of water, steam reforming, lab-scale metal-acid process, thermochemical methods, or anaerobic corrosion. Many countries are aiming at a hydrogen economy.

[4] In the Fischer-Tropsch process, CO and H2 are both essential building blocks, which are often produced by converting carbon-rich feedstocks (e.g., coal). A mixture of CO and H2 - syngas - can combine to produce various liquid fuels, e.g., 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 in order to produce the desired compounds. Conventional techniques require extensive and expensive separation and purification processes to obtain the CO and H2 as building blocks.

[5] Clearly there is an increasing need and interest to develop new technological platforms to produce these building blocks and valuable products. This disclosure discusses new electrochemical devices that are suited for production of CO and H2 via efficient electrochemical pathways. Furthermore, the method and system as disclosed herein do not require the extensive and expensive separation and purification processes that are needed in traditional technologies.

SUMMARY

[6] Herein discussed is a method of producing hydrogen or carbon monoxide or both comprising: (a) providing an electrochemical reactor comprising an anode, a cathode, and a mixed-conducting electrolyte between the anode and the cathode, (b) introducing a first fluid to the anode, wherein the first fluid provides a reducing atmosphere for the anode, and (c) introducing a second fluid to the cathode, wherein the second fluid provides a reducing atmosphere for the cathode, wherein the direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, and wherein the direction of the bulk flow of the first fluid changes in the reactor.

[7] In an embodiment, the first fluid comprises a fuel. In an embodiment, the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, a hydrocarbon, or combinations thereof. In an embodiment, the second fluid comprises water or carbon dioxide or both.

[8] In an embodiment, the cathode is configured to reduce water to hydrogen electrochemically or configured to reduce carbon dioxide to carbon monoxide electrochemically. In an embodiment, the cathode is configured to simultaneously reduce water and carbon dioxide to hydrogen and carbon monoxide electrochemically.

[9] In an embodiment, the cathode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, LSGM, CoCGO, LST, and combinations thereof.

[10] In an embodiment, the anode and the cathode have the same elements. In an embodiment, the anode and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr- SCZ or LST(lanthanum-doped strontium titanate)-SCZ.

[11] In an embodiment, the anode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, LSGM, CoCGO, LST, and combinations thereof. In an embodiment, the anode comprises doped or undoped ceria and a material selected from the group consisting of Cu, CuO, 12O, Ag, Ag2O, Au, AU2O, AU2O3, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, LST, SCZ, stainless steel, and combinations thereof. [12] In an embodiment, the electrolyte comprises an electronically conducting phase and an ionically conducting phase; wherein the electronically conducting phase comprises doped lanthanum chromite or LST or an electronically conductive metal or 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 gallate magnesite (LSGM), scandia-stabilized zirconia (SSZ), Sc and Ce doped zirconia (SCZ), and combinations thereof.

[13] In an embodiment, the electrolyte comprises CoCGO or LST -stabilized zirconia. In an embodiment, the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria- stabilized zirconia), and wherein the LST comprises LaSrCaTiCh. In an embodiment, the electrolyte comprises Nickel, Copper, Cobalt, Lanthanum, Strontium, Titanium, or Niobium -doped zirconia.

[14] In an embodiment, the electrolyte, the anode, and the cathode have the same elements. In an embodiment, the electrolyte, the anode, and the cathode comprise Ni-YSZ or LaSrFeCr- SSZ or LaSrFeCr-SCZ or LST-SCZ.

[15] In an embodiment, the anode exhaust exchanges heat with the first fluid and the cathode exhaust exchanges heat with the second fluid. In an embodiment, hydrogen or carbon monoxide or both are extracted from the cathode exhaust.

[16] Also discussed herein is an electrochemical reactor comprising an anode, a cathode, and a mixed-conducting electrolyte between the anode and the cathode, wherein the anode receives a first fluid and the cathode receives a second fluid, wherein the direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, wherein the direction of the bulk flow of the first fluid changes in the reactor, and wherein the first fluid provides a reducing atmosphere for the anode and the second fluid provides a reducing atmosphere for the cathode.

[17] Further aspects and embodiments are provided in the following drawings, detailed description, and claims. Unless specified otherwise, the features as described herein are combinable and all such combinations are within the scope of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[18] The following drawings are provided to illustrate certain embodiments described herein. The drawings are merely illustrative and are not intended to limit the scope of claimed inventions and are not intended to show every potential feature or embodiment of the claimed inventions. The drawings are not necessarily drawn to scale; in some instances, certain elements of the drawing may be enlarged with respect to other elements of the drawing for purposes of illustration.

[19] Fig. 1 illustrates a cross sectional side view (not to scale) of a counter flow electrochemical reactor, according to an embodiment of this disclosure.

[20] Fig. 2A illustrates a section of an electrochemical reactor (not to scale), according to an embodiment of this disclosure.

[21] Fig. 2B illustrates a cross sectional view (not to scale) of the section shown in Fig. 2A, according to an embodiment of this disclosure.

DETAILED DESCRIPTION

Overview

[22] The following terms and phrases have the meanings indicated below, unless otherwise provided herein. This disclosure may employ other terms and phrases not expressly defined herein. Such other terms and phrases shall have the meanings that they would possess within the context of this disclosure to those of ordinary skill in the art. In some instances, 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.

[23] 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” encompasses a single substituent as well as two or more substituents, and the like. As used herein, “for example,” “for instance,” “such as,” or “including” are meant to introduce examples that further clarify more general subject matter. Unless otherwise expressly indicated, such examples are provided only as an aid for understanding embodiments illustrated in the present disclosure and are not meant to be limiting in any fashion. Nor do these phrases indicate any kind of preference for the disclosed embodiment.

[24] As used herein, compositions and materials are used interchangeably unless otherwise specified. Each composition/material may have multiple elements, phases, and components. Heating as used herein refers to actively adding energy to the compositions or materials.

[25] As used herein, YSZ refers to yttria-stabilized zirconia; SDC refers to samaria-doped ceria; SSZ refers to scandia-stabilized zirconia; LSGM refers to lanthanum strontium gallate magnesite. [26] In this disclosure, no substantial amount of H2 means that the volume content of the hydrogen is no greater than 5%, or no greater than 3%, or no greater than 2%, or no greater than 1%, or no greater than 0.5%, or no greater than 0.1%, or no greater than 0.05%.

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

[28] A mixed conducting electrolyte is able to transport both electrons and ions. Ionic conductivity includes ionic species such as oxygen ions (or oxide ions), protons, halogenide anions, chalcogenide anions. In various embodiments, the mixed conducting electrolyte of this disclosure comprises an electronically conducting phase and an ionically conducting phase.

[29] In this disclosure, the cross section of the tubulars is only illustrative and not limiting. The cross section of the tubulars is any suitable shape as known to one skilled in the art, such as circular, square, square with rounded corners, rectangle, rectangle with rounded corners, triangle, hexagon, pentagon, oval, irregular shape, etc. Axial direction is the direction along the length of the tubulars. Circumferential direction is the direction around the circumference of the cross section of the tubulars.

[30] In this disclosure, electrical resistance between two points is the ratio between the voltage applied to the current flowing between the two points. The unit of electrical resistance is, for example, ohms. Ionic resistance between two points is the ratio between the voltage applied to the current flowing between the two points caused by ionic movement, such as oxide ions. The unit of ionic resistance is, for example, ohms.

[31] As used herein, ceria refers to cerium oxide, also known as ceric oxide, ceric dioxide, or cerium dioxide, 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 oxides, which includes all the oxidation states of chromium oxides.

[32] A layer or substance being impermeable as used herein refers to it being impermeable to fluid flow. For example, an impermeable layer or substance has a permeability of less than 1 micro darcy, or less than 1 nano darcy.

[33] In this disclosure, sintering refers to a process to form a solid mass of material by heat or pressure, or a combination thereof, without melting the material to the extent of liquefaction. For example, material particles are coalesced into a solid or porous mass by being heated, wherein atoms in the material particles diffuse across the boundaries of the particles, causing the particles to fuse together and form one solid piece.

[34] The term “/// situ" in this disclosure refers to the treatment (e.g., heating or cracking) process being performed either at the same location or in the same device. For example, ammonia cracking taking place in the electrochemical device at the anode is considered in situ.

[35] Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electrical potential as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving between electrodes via an electronically-conducting phase (typically, but not necessarily, an external electrical circuit), separated by an ionically-conducting and electronically insulating electrolyte (or ionic species in a solution). When a chemical reaction is effected by a potential difference, as in electrolysis, or if electrical potential results from a chemical reaction as in a battery or fuel cell, it is called an electrochemical reaction. Unlike chemical reactions, in electrochemical reactions electrons (and necessarily resulting ions), are not transferred directly between molecules, but via the aforementioned electronically conducting and ionically conducting circuits, respectively. This phenomenon is what distinguishes an electrochemical reaction from a chemical reaction.

[36] Related to the electrochemical device and methods of use, various components of the reactor are described such as electrodes and electrolytes along with materials of construction of the components. The following description recites various aspects and embodiments of the inventions disclosed herein. No particular embodiment is intended to define the scope of the invention. Rather, the embodiments provide non-limiting examples of various compositions and methods that are included within the scope of the claimed inventions. The description is to be read from the perspective of one of ordinary skill in the art. Therefore, information that is well-known to the ordinarily skilled artisan is not necessarily included.

[37] An interconnect in an electrochemical device (e.g., a fuel cell) is often either metallic or ceramic that is placed between the individual cells or repeat units. Its purpose is to connect each cell or repeat unit so that electricity can be distributed or combined. An interconnect is also referred to as a bipolar plate in an electrochemical device. An interconnect being an impermeable layer as used herein refers to it being a layer that is impermeable to fluid flow. Counter Flow Electrochemical Reactor

[38] Contrary to conventional art, an electrochemical reactor is designed, which comprises a multiplicity of electrochemical tubulars, wherein each of the electrochemical tubulars comprises an anode, a cathode, and a mixed-conducting electrolyte between and in contact with the anode and the cathode. The anode receives a first fluid, wherein the first fluid provides a reducing atmosphere for the anode. The cathode receives a second fluid, wherein the second fluid provides a reducing atmosphere for the cathode. The first fluid and the second fluid do not come in contact with each other because the electrolyte only allows ions and electrons to pass through. The electrochemical reactions taking place in the reactor involve the exchange of ions and/or electrons through the electrolyte. These are different from traditional reactions via chemical pathways, which involve direct combination of reactants. In the reactor, the direction of the bulk flow of the first fluid changes and the direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode.

[39] As shown in Fig. 1, an electrochemical reactor 100 has a casing 101 and a multiplicity of tubulars 102. Casing 101 separates the reactor into an upper chamber and a lower chamber. Tubular 102 comprises the anode, the cathode, and the electrolyte, which are further illustrated in Fig. 2A-2B. The flow of the first fluid is represented by dashed arrows 103. The flow of the second fluid is represented by solid arrows 104. Flow 103 and flow 104 both change directions in the reactor 100. Furthermore, flow 103 is opposite to flow 104 in direction along the length of the anode in the reactor. In this disclosure, fluid flow refers to the bulk flow of the fluid, not to diffusion or local convection or microscopic turbulences, unless otherwise specified. Reactor 100 comprises a manifold 105 that is configured to change the directions of flow 103 and flow 104 and to separate the first fluid from the second fluid. In the embodiment as shown in Fig. 1, flow 103 and flow 104 are counter current in manifold 105. In other embodiments, flow 103 and flow 104 may be configured differently in manifold 105. In some cases, manifold 105 is made of the same material as casing 101. In some cases, manifold 105 is made of the same materials as tubulars 102. In some cases, manifold 105 is made of other suitable materials as known to one skilled in the art.

[40] A section of the reactor is shown in Fig. 2A and its cross-sectional view shown in Fig. 2B. The cross section may be any shape as known to one skilled in the art, e.g., circular, oval, square, rounded square, rectangle, rounded rectangle, hexagon, etc. Fig. 2A and 2B are mere illustrations and not limiting. Fig. 2A and 2B illustrate a section 200 of the reactor, according to an embodiment of this disclosure. 202 represents a first electrode being an anode or cathode, 206 represents the electrolyte, 204 represents a second electrode being a cathode or anode, and 208 represents a fluid passage.

[41] In an embodiment, the first fluid comprises a fuel. In various cases, the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, a hydrocarbon, or combinations thereof. In an embodiment, the second fluid comprises water or carbon dioxide or both.

[42] In an embodiment, the cathode is configured to reduce water to hydrogen electrochemically or configured to reduce carbon dioxide to carbon monoxide electrochemically. In an embodiment, the cathode is configured to simultaneously reduce water and carbon dioxide to hydrogen and carbon monoxide electrochemically. In an embodiment, the cathode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, LSGM, CoCGO, LST, and combinations thereof.

[43] In an embodiment, the anode and the cathode have the same elements. In an embodiment, the anode and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr- SCZ or LST(lanthanum-doped strontium titanate)-SCZ.

[44] In an embodiment, the anode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, LSGM, CoCGO, LST, and combinations thereof. In an embodiment, the anode comprises doped or undoped ceria and a material selected from the group consisting of Cu, CuO, 12O, Ag, Ag2O, Au, AU2O, AU2O3, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, LST, SCZ, stainless steel, and combinations thereof.

[45] In an embodiment, the electrolyte comprises an electronically conducting phase and an ionically conducting phase; wherein the electronically conducting phase comprises doped lanthanum chromite or LST or an electronically conductive metal or 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 gallate magnesite (LSGM), scandia-stabilized zirconia (SSZ), Sc and Ce doped zirconia (SCZ), and combinations thereof. In an embodiment, the electrolyte comprises CoCGO or LST -stabilized zirconia. In an embodiment, the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria-stabilized zirconia), and wherein the LST comprises LaSrCaTiO3. In an embodiment, the electrolyte comprises Nickel, Copper, Cobalt, Lanthanum, Strontium, Titanium, or Niobium -doped zirconia. [46] In an embodiment, the electrolyte comprises cobalt-CGO (CoCGO), i.e., cobalt doped CGO. In an embodiment, the electrolyte consists essentially of CoCGO. In an embodiment, the electrolyte consists of CoCGO. In an embodiment, the electrolyte comprises LST (lanthanum-doped strontium titanate)-YSZ or LST-SSZ or LST-SCZ (scandia-ceria-stabilized zirconia). In an embodiment, the electrolyte consists essentially of LST-YSZ or LST-SSZ or LST-SCZ. In an embodiment, the electrolyte 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 phase and the YSZ phase percolate each other. In this disclosure, LST-SSZ refers to a composite of LST and SSZ. In various embodiments, the LST phase and the SSZ phase percolate each other. In this disclosure, LST-SCZ refers to a composite of LST and SCZ. In various embodiments, the LST phase and the SCZ phase percolate each other. YSZ, SSZ, and SCZ are types of stabilized zirconia’s.

[47] In an embodiment, the electrolyte, the anode, and the cathode have the same elements. In an embodiment, the electrolyte, the anode, and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST-SCZ.

[48] In an embodiment, the anode exhaust exchanges heat with the first fluid and the cathode exhaust exchanges heat with the second fluid. In an embodiment, hydrogen or carbon monoxide or both are extracted from the cathode exhaust.

Method of Use

[49] In an embodiment, the anode and the cathode are both exposed to reducing environments during the entire time of operation. In an embodiment, the anode is configured to come in contact with a fuel. In an embodiment, the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, a hydrocarbon, or combinations thereof. In an embodiment, the cathode is configured to reduce water to hydrogen electrochemically or configured to reduce carbon dioxide to carbon monoxide electrochemically. In an embodiment, the cathode is configured to simultaneously reduce water and carbon dioxide to hydrogen and carbon monoxide electrochemically. In various embodiments, the entire reactor is operated at a temperature no less than 500°C.

[50] In one embodiment, a first stream containing a fuel is introduced to the anode; simultaneously, steam is provided to the cathode along with hydrogen. In another embodiment, a first stream containing a fuel is introduced to the anode; simultaneously, carbon dioxide is provided to the cathode along with carbon monoxide. In another embodiment, a first stream containing a fuel is introduced to the anode; simultaneously, steam and carbon dioxide are provided to the cathode along with hydrogen and/or carbon monoxide. In such cases, water is reduced to hydrogen electrochemically and CO2 is reduced to CO electrochemically. Syngas is thus produced from the reactor.

[51] The electrolyte does not allow the fluids on the anode side and on the cathode side to come in contact with each other. The overpotential of the electrochemical reactions is such that oxide ions are passed through the electrolyte from the cathode to the anode to oxidize the fuel, electrons are passed through the electrolyte from the anode to the cathode to reduce water to hydrogen or to reduce carbon dioxide to carbon monoxide, when the electrolyte is mixed conducting.

Advantages

[52] The reactor of this disclosure for CO and H2 and syngas production has various advantages. This reactor has no electricity input or output. Thus, it is not a fuel cell and not an electrolyser. CO generation from CO2 is desirable because it reduces greenhouse gas emission. Making CO and H2 locally (on site) is inherently safer than transporting CO and H2 in pressurized containers or vessels. The process of this disclosure utilizes efficient electrochemical pathways but needs no electricity. As such, such a system can be operated in remote locations that are off grid.

[53] The CO/CO2 and H2/H2O separation from the cathode exhaust is easy and inexpensive. Simple absorption or condensation is sufficient. As such, the method and system of this disclosure are cost competitive both in capital equipment and in operational expenses.

[54] In various embodiments, the ratio of H2/CO co-production is controlled by varying the input ratio of H2O/CO2, by varying the operation temperature, by varying the fuel composition, or combinations thereof. As such, the produced H2/CO is suitable for various downstream chemical productions without the need for further purification or modification. This is another major advantage of the process and system of this disclosure.

[55] In addition, unlike most electrochemical reactors wherein the fluids on the anode and cathode sides are in cross flow pattern, the reactor of this disclosure enables the fluids on the anode and cathode sides to be counter flow along the entire reactive path of the reactor. This enables the reactor to have higher efficiency in utilizing heat and reactive species.

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

[57] Additionally, certain terms are used throughout the description and claims to refer to particular components or steps. As one skilled in the art appreciates, various entities may refer to the same component or process step by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention. Further, the terms and naming convention used herein are not intended to distinguish between components, features, and/or steps that differ in name but not in function.

[58] 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 form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of this disclosure.

[59] A. A method of producing hydrogen or carbon monoxide or both comprising: providing an electrochemical reactor comprising an anode, a cathode, and a mixed- conducting electrolyte between the anode and the cathode; introducing a first fluid to the anode, wherein the first fluid provides a reducing atmosphere for the anode; and introducing a second fluid to the cathode, wherein the second fluid provides a reducing atmosphere for the cathode, wherein a direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, and wherein the direction of the bulk flow of the first fluid changes in the reactor.

[60] B. The method of Paragraph A, wherein the first fluid comprises a fuel.

[61] C. The method of either of Paragraph B, wherein the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, a hydrocarbon, or combinations thereof.

[62] D. The method of any of Paragraphs A-C, wherein the cathode is configured to reduce water to hydrogen electrochemically or configured to reduce carbon dioxide to carbon monoxide electrochemically. [63] E. The method of any of Paragraphs A-D, wherein the cathode is configured to simultaneously reduce water and carbon dioxide to hydrogen and carbon monoxide electrochemically.

[64] F. The method of any of Paragraphs A-E, wherein the second fluid comprises water or carbon dioxide or both.

[65] G. The method of any of Paragraphs A-F, wherein the cathode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, LSGM, CoCGO, LST, and combinations thereof.

[66] H. The method of any of Paragraphs A-G, wherein the anode and the cathode have the same elements.

[67] I. The method of a Paragraph H, wherein the anode and the cathode comprise Ni- YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST(lanthanum-doped strontium titanate)- scz.

[68] J. The method of any of Paragraphs A-I, wherein the anode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, LSGM, CoCGO, LST, and combinations thereof.

[69] K. The method of any of Paragraphs A- J, wherein the anode comprises doped or undoped ceria and a material selected from the group consisting of Cu, CuO, Cu20, Ag, Ag2O, Au, Au20, Au2O3, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, LST, SCZ, stainless steel, and combinations thereof.

[70] L. The method of any of Paragraphs A-K, wherein the electrolyte comprises an electronically conducting phase and an ionically conducting phase; wherein the electronically conducting phase comprises doped lanthanum chromite or LST or an electronically conductive metal or 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 gallate magnesite (LSGM), scandia-stabilized zirconia (SSZ), Sc and Ce doped zirconia (SCZ), and combinations thereof.

[71] M. The method of any of Paragraphs A-L, wherein the electrolyte comprises CoCGO or LST -stabilized zirconia.

[72] N. The method of Paragraph M, wherein the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria-stabilized zirconia), and wherein the LST comprises LaSrCaTiO3. [73] O. The method of any of Paragraphs A-N, wherein the electrolyte comprises nickel, copper, cobalt, lanthanum, strontium, titanium, or niobium -doped zirconia.

[74] P. The method of any of Paragraphs A-O, wherein the electrolyte, the anode, and the cathode have the same elements.

[75] Q. The method of Paragraph P, wherein the electrolyte, the anode, and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST-SCZ.

[76] R. The method of any of Paragraphs A-Q, wherein an anode exhaust exchanges heat with the first fluid and a cathode exhaust exchanges heat with the second fluid.

[77] S. The method of any of Paragraphs A-S, wherein hydrogen or carbon monoxide or both are extracted from a cathode exhaust.

[78] T. An electrochemical reactor comprising an anode, a cathode, and a mixed- conducting electrolyte between the anode and the cathode, wherein the anode receives a first fluid and the cathode receives a second fluid, wherein a direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, wherein the direction of the bulk flow of the first fluid changes in the reactor, and wherein the first fluid provides a reducing atmosphere for the anode and the second fluid provides a reducing atmosphere for the cathode.

Claims

WHAT IS CLAIMED IS: We claim:

1. A method of producing hydrogen or carbon monoxide or both comprising: a. providing an electrochemical reactor comprising an anode, a cathode, and a mixed-conducting electrolyte between the anode and the cathode; b. introducing a first fluid to the anode, wherein the first fluid provides a reducing atmosphere for the anode; and c. introducing a second fluid to the cathode, wherein the second fluid provides a reducing atmosphere for the cathode, wherein a direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, and wherein the direction of the bulk flow of the first fluid changes in the reactor.

2. The method of claim 1, wherein the first fluid comprises a fuel.

3. The method of claim 2, wherein the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, a hydrocarbon, or combinations thereof.

4. The method of claim 1, wherein the cathode is configured to reduce water to hydrogen electrochemically or configured to reduce carbon dioxide to carbon monoxide electrochemically.

5. The method of claim 1, wherein the cathode is configured to simultaneously reduce water and carbon dioxide to hydrogen and carbon monoxide electrochemically.

6. The method of claim 1, wherein the second fluid comprises water or carbon dioxide or both.

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

8. The method of claim 1, wherein the anode and the cathode have the same elements.

9. The method of claim 8, wherein the anode and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST(lanthanum-doped strontium titanate)-SCZ.

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

11. The method of claim 1, wherein the anode comprises doped or undoped ceria and a material selected from the group consisting of Cu, CuO, 12O, Ag, Ag2O, Au, AU2O, AU₂O3, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, LST, SCZ, stainless steel, and combinations thereof.

12. The method of claim 1, wherein the electrolyte comprises an electronically conducting phase and an ionically conducting phase; wherein the electronically conducting phase comprises doped lanthanum chromite or LST or an electronically conductive metal or 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 gallate magnesite (LSGM), scandia- stabilized zirconia (SSZ), Sc and Ce doped zirconia (SCZ), and combinations thereof.

13. The method of claim 1, wherein the electrolyte comprises CoCGO or LST -stabilized zirconia.

14. The method of claim 13, wherein the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria-stabilized zirconia), and wherein the LST comprises LaSrCaTiCh.

15. The method of claim 1, wherein the electrolyte comprises nickel, copper, cobalt, lanthanum, strontium, titanium, or niobium -doped zirconia.

16. The method of claim 1, wherein the electrolyte, the anode, and the cathode have the same elements.

17. The method of claim 16, wherein the electrolyte, the anode, and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST-SCZ.

18. The method of claim 1, wherein an anode exhaust exchanges heat with the first fluid and a cathode exhaust exchanges heat with the second fluid.

19. The method of claim 1, wherein hydrogen or carbon monoxide or both are extracted from a cathode exhaust.

20. An electrochemical reactor comprising an anode, a cathode, and a mixed-conducting electrolyte between the anode and the cathode, wherein the anode receives a first fluid and the cathode receives a second fluid, wherein a direction of the bulk flow of the first fluid is opposite that of the second fluid at every location along the length of the anode, wherein the direction of the bulk flow of the first fluid changes in the reactor, and wherein the first fluid provides a reducing atmosphere for the anode and the second fluid provides a reducing atmosphere for the cathode.