REACTOR ASSEMBLY AND METHOD OF USE

Abstract

A reactor assembly includes a multiplicity of electrochemical reactors, wherein each of the electrochemical reactors comprises an anode, a cathode, and a membrane between and in contact with the anode and the cathode, wherein the anode or the cathode forms a fluid passage having an inlet and an outlet, wherein the surface area of the fluid passage in contact with the anode or cathode is at least 25 times of the combined cross-sectional area of the inlet and the outlet; wherein the minimum distance between the reactors is no greater than 2 cm; and wherein the reactors have no interconnects and no direct contact with one another.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63/508,203 filed Jun. 14, 2023, the entire disclosure of which is hereby incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to electrochemical reactors. More specifically, this disclosure relates to the design of electrochemical reactor assemblies and method of use.

BACKGROUND

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.

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.

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.

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

Herein discussed is a reactor assembly comprising a multiplicity of electrochemical reactors, wherein each of the electrochemical reactors comprises an anode, a cathode, and a membrane between and in contact with the anode and the cathode, wherein the anode or the cathode forms a fluid passage having an inlet and an outlet, wherein the surface area of the fluid passage in contact with the anode or cathode is at least 25 times of the combined cross-sectional area of the inlet and the outlet; wherein the minimum distance between the reactors is no greater than 2 cm; and wherein the reactors have no interconnects and no direct contact with one another.

In an embodiment, wherein tortuosity of the fluid passage is no less than 10, wherein tortuosity is the ratio of fluid flow path length to the straight distance between the inlet and the outlet. In an embodiment, tortuosity of the fluid passage is no less than 20, or no less than 30, or no less than 40, or no less than 50. In an embodiment, the surface area of the fluid passage in contact with the anode or cathode is at least 50 times or at least 100 times or at least 200 times or at least 300 times or at least 400 times or at least 500 times of the combined cross-sectional area of the inlet and the outlet.

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. 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. 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, Cu₂O, Ag, Ag₂O, Au, Au₂O, Au₂O₃, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, LST, SCZ, stainless steel, and combinations thereof. In an embodiment, the membrane is electronically insulating.

In an embodiment, the membrane is mixed conducting. In an embodiment, the membrane 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 membrane 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 membrane comprises Nickel, Copper, Cobalt, Lanthanum, Strontium, Titanium, or Niobium-doped zirconia.

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

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 an embodiment, electrical resistance between the anode and cathode is no greater than ionic resistance between the anode and cathode for oxide ions.

In an embodiment, the reactor assembly produces no electricity and receives no electricity. In an embodiment, the minimum distance between the reactors is no greater than 1 cm. In an embodiment, the electrical resistance between the anode and the cathode in the same reactor is less than the electrical resistance between said anode and another cathode in an adjacent reactor.

Further discussed herein is a reactor assembly comprising a multiplicity of electrochemical reactors, wherein each of the electrochemical reactors comprises an anode, a cathode, and a membrane between and in contact with the anode and the cathode, wherein the anode or the cathode forms a fluid passage having an inlet and an outlet, wherein tortuosity of the fluid passage is no less than 10, wherein tortuosity is the ratio of fluid flow path length to the straight distance between the inlet and the outlet; wherein the minimum distance between the reactors is no greater than 2 cm; and wherein the reactors have no interconnects and no direct contact with one another.

In an embodiment, the minimum distance between the reactors is no greater than 1 cm. In an embodiment, the electrical resistance between the anode and the cathode in the same reactor is less than the electrical resistance between said anode and another cathode in an adjacent reactor.

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

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 claims and are not intended to show every potential feature or embodiment of the claims. 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.

FIG. 1A-1E illustrate cross sectional side views (not to scale) of electrochemical reactors, according to various embodiments of this disclosure.

FIG. 1F illustrates a side profile view (not to scale) of an electrochemical reactor that is orthogonal to the views shown in FIG. 1A-1E, according to an embodiment of this disclosure.

FIG. 1G illustrates a side provide view (not to scale) of an electrochemical reactor assembly, according to an embodiment of this disclosure.

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

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

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.

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.

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.

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.

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%.

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 Gd:CeO₂). 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.

A mixed conducting membrane 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 embodiment, the mixed conducting membrane of this disclosure comprises an electronically conducting phase and an ionically conducting phase.

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.

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.

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.

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.

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.

The term “in 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.

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 membrane (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.

Related to the electrochemical device and methods of use, various components of the reactor are described such as electrodes and membranes along with materials of construction of the components. The following description recites various aspects and embodiments of the methods and devices disclosed herein. No particular embodiment is intended to define the scope of the claimed methods and/or devices. Rather, the embodiments provide non-limiting examples of various compositions and methods that are included within the scope of the claimed methods and/or devices. 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.

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.

Reactor Assembly

Contrary to conventional art, an electrochemical reactor assembly is designed, which comprises a multiplicity of electrochemical reactors, wherein each of the electrochemical reactors comprises an anode, a cathode, and a membrane between and in contact with the anode and the cathode, wherein the anode or the cathode forms a fluid passage having an inlet and an outlet, wherein the surface area of the fluid passage in contact with the anode or cathode is at least 25 times of the combined cross-sectional area of the inlet and the outlet; wherein the minimum distance between the reactors is no greater than 2 cm; and wherein the reactors have no interconnects and no direct contact with one another. In some cases, the minimum distance between the reactors is no greater than 1 cm.

In an embodiment, the surface area of the fluid passage in contact with the anode or cathode is at least 50 times or at least 100 times or at least 200 times or at least 300 times or at least 400 times or at least 500 times of the combined cross-sectional area of the inlet and the outlet.

In an embodiment, tortuosity of the fluid passage is no less than 10, wherein tortuosity is the ratio of fluid flow path length to the straight distance between the inlet and the outlet. In an embodiment, tortuosity of the fluid passage is no less than 20, or no less than 30, or no less than 40, or no less than 50.

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. 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. 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, Cu₂O, Ag, Ag₂O, Au, Au₂O, Au₂O₃, Pt, Pd, Ru, Rh, Ir, LaCaCr, LaSrCrFe, YSZ, CGO, SDC, SSZ, LSGM, LST, SCZ, stainless steel, and combinations thereof. In an embodiment, the membrane is electronically insulating.

In an embodiment, the membrane is mixed conducting. In an embodiment, the membrane conducts both oxide ions and electrons. In an embodiment, the membrane 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 membrane 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 membrane comprises Nickel, Copper, Cobalt, Lanthanum, Strontium, Titanium, or Niobium-doped zirconia.

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

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 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. In an embodiment, the LST comprises LaSrCaTiO3. In an embodiment, the membrane comprises Nickel, Copper, Cobalt, or Niobium-doped zirconia.

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 an embodiment, electrical resistance between the anode and cathode is no greater than ionic resistance between the anode and cathode for oxide ions. In an embodiment, the reactor produces no electricity and receives no electricity. In an embodiment, the reactor comprises no interconnects or current collectors. In an embodiment, the anode and the cathode each have a thickness of no greater than 100 microns. In an embodiment, the anode and the cathode each have a thickness of no greater than 20 microns.

In a further embodiment, a reactor assembly comprises a multiplicity of electrochemical reactors, wherein each of the electrochemical reactors comprises an anode, a cathode, and a membrane between and in contact with the anode and the cathode, wherein the anode or the cathode forms a fluid passage having an inlet and an outlet, wherein tortuosity of the fluid passage is no less than 10, wherein tortuosity is the ratio of fluid flow path length to the straight distance between the inlet and the outlet; wherein the minimum distance between the reactors is no greater than 2 cm; and wherein the reactors have no interconnects and no direct contact with one another. In an embodiment, the minimum distance between the reactors is no greater than 1 cm.

The electrochemical reactions taking place in the reactor involve the exchange of ions and/or electrons through the membrane. These are different from traditional reactions via chemical pathways, which involve direct combination of reactants.

As shown in FIG. 1A-1F, such an electrochemical reactor 100 with inlet 101 and outlet 102 has many configurations. Reactor wall 103 comprises the anode, the cathode, and the membrane, which are further illustrated in FIG. 2A-2B. FIG. 1G illustrates a multiplicity of such reactors closely packed in proximity one to another.

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 membrane, 204 represents a second electrode being a cathode or anode, and 208 represents the fluid passage.

Method of Use

In an embodiment, the anode is the internal of the reactor—202 is the anode and 204 is the cathode as shown in FIG. 2A and 2B. A first stream containing a fuel is introduced to the anode via inlet 101, passes through fluid passage 208, and exits via outlet 102. Simultaneously, steam is provided to the cathode along with hydrogen. The entire reactor is operated at a temperature no less than 500° C.

The membrane does not allow the fluids on the anode side and on the cathode side to come in contact with each other. The overpotential of such electrochemical reactions is such that oxide ions are passed through the membrane from the anode to the cathode to oxidize the fuel, electrons are passed through the membrane from the cathode to the anode to reduce water to hydrogen, when the membrane is mixed conducting. When the membrane is electrically insulating, the electrons are passed from the cathode to the anode via a conductor within the same reactor.

In another embodiment, carbon dioxide is provided to the cathode along with carbon monoxide. The overpotential of such electrochemical reactions is such that oxide ions are passed through the membrane from the anode to the cathode to oxidize the fuel, electrons are passed through the membrane from the cathode to the anode to reduce CO₂ to CO, when the membrane is mixed conducting. When the membrane is electrically insulating, the electrons are passed from the cathode to the anode via a conductor within the same reactor. The entire reactor is operated at a temperature no less than 500° C.

In another embodiment, carbon dioxide and steam are provided to the cathode at the same time. In such cases, water is reduced to hydrogen electrochemically and CO₂ is reduced to CO electrochemically. Syngas is thus produced from the reactor. The entire reactor is operated at a temperature no less than 500° C.

Advantages

The reactor assembly of this disclosure is fundamentally different from fuel cells and electrolysers not only because it does not receive or produce electricity but also because its structure is vastly different. In a fuel cell or an electrolyser, each unit comprises an anode, a cathode, an electrolyte, and an interconnect, which interconnect is in contact with the anode of this unit and the cathode of the adjacent unit. The interconnect ensures that the electrical resistance between the anode of this unit and the cathode of the adjacent unit is less than that between the anode and cathode of the same unit. This is the basic working principle for a fuel cell to produce electricity for an external circuit and for an electrolyser to receive electricity from an external circuit. The reactor assembly of this disclosure is exactly the opposite of fuel cells and electrolysers, i.e., in this reactor assembly, (1) each reactor has no interconnects and ensures that electrons are returned from the anode to the cathode in the same reactor; and (2) the electrical resistance between the anode and the cathode in the same reactor is less than the electrical resistance between said anode and another cathode in an adjacent reactor. Fuel cells and electrolysers cannot be configured this way because they would have been short-circuited between the anode and the cathode in each unit and would have failed to perform as intended.

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.

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.

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.

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

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 claimed methods and/or devices. 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.

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.

Other embodiments are set forth in the following claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A reactor assembly comprising:

a multiplicity of electrochemical reactors, wherein each of the electrochemical reactors comprises: an anode; a cathode; and a membrane between and in contact with the anode and the cathode; wherein: the anode or the cathode forms a fluid passage having an inlet and an outlet; a surface area of the fluid passage in contact with the anode or the cathode is at least 25 times of a combined cross-sectional area of the inlet and the outlet; a minimum distance between the electrochemical reactors is no greater than 2 cm; and the electrochemical reactors have no interconnects and no direct contact with one another.

2. The reactor assembly of claim 1, wherein a tortuosity of the fluid passage is no less than 10, wherein the tortuosity is a ratio of fluid flow path length to a straight distance between the inlet and the outlet.

3. The reactor assembly of claim 2, wherein the tortuosity of the fluid passage is no less than 20, or no less than 30, or no less than 40, or no less than 50.

4. The reactor assembly of claim 1, wherein the surface area of the fluid passage in contact with the anode or the cathode is at least 50 times or at least 100 times or at least 200 times or at least 300 times or at least 400 times or at least 500 times of the combined cross-sectional area of the inlet and the outlet.

5. The reactor assembly 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 a combination of any two or more thereof.

6. The reactor assembly of claim 1, wherein the anode and the cathode have the same elements.

7. The reactor assembly of claim 6, wherein the anode and the cathode comprise Ni-YSZ LaSrFeCr-SSZ LaSrFeCr-SCZ or LST(lanthanum-doped strontium titanate)-SCZ.

8. The reactor assembly 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 a combination of any two or more thereof.

9. The reactor assembly of claim 1, wherein the anode comprises doped or undoped ceria 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, LST, SCZ, stainless steel, and a combination of any two or more thereof.

10. The reactor assembly of claim 1, wherein the membrane is mixed conducting.

11. The reactor assembly of claim 1, wherein the membrane 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.

12. The reactor assembly of claim 1, wherein the membrane comprises CoCGO or LST-stabilized zirconia.

13. The reactor assembly of claim 12, wherein the stabilized zirconia comprises YSZ or SSZ or SCZ (scandia-ceria-stabilized zirconia), and wherein the LST comprises LaSrCaTiO3.

14. The reactor assembly of claim 1, wherein the membrane comprises nickel, copper, cobalt, lanthanum, strontium, titanium, or niobium-doped zirconia.

15. The reactor assembly of claim 1, wherein the membrane, the anode, and the cathode have the same elements.

16. The reactor assembly of claim 15, wherein the membrane, the anode, and the cathode comprise Ni-YSZ or LaSrFeCr-SSZ or LaSrFeCr-SCZ or LST-SCZ.

17. The reactor assembly of claim 1, wherein electrical resistance between the anode and the cathode is no greater than ionic resistance between the anode and the cathode for oxide ions.

18. The reactor assembly of claim 1, wherein the minimum distance between the electrochemical reactors is no greater than 1 cm.

19. The reactor assembly of claim 1, wherein the electrical resistance between the anode and the cathode in the same reactor is less than the electrical resistance between said anode and another cathode in an adjacent reactor.

20. A reactor assembly comprising a multiplicity of electrochemical reactors;

wherein: each of the electrochemical reactors comprises an anode, a cathode, and a membrane between and in contact with the anode and the cathode; the anode or the cathode forms a fluid passage having an inlet and an outlet; a tortuosity of the fluid passage is no less than 10, wherein the tortuosity is a ratio of fluid flow path length to a straight distance between the inlet and the outlet; a minimum distance between the electrochemical reactors is no greater than 2 cm; and the electrochemical reactors have no interconnects and no direct contact with one another.