Electrochemical water gas shift reactor and methods of using the same

Abstract

Discussed herein is an electrochemical reactor comprising an ionically conductive membrane, wherein the reactor electrochemically performs a water gas shift reaction without electrical input, wherein the electrochemical water gas shift reaction involves the exchange of ions through the membrane and comprises a forward water gas shift reaction, or a reverse water gas shift reaction, or both. Also discussed herein is a reactor comprising: a bifunctional layer and a mixed conductive membrane; wherein the bifunctional layer and the mixed conductive membrane are in contact with each other, and wherein the bifunctional layer catalyzes a reverse water gas shift (RWGS) reaction and functions as an anode in an electrochemical reaction.

Description

Technical Field

[0001] This invention generally relates to water-gas shift reactions. More specifically, this invention relates to water-gas shift reactions that participate in electrochemical pathways. Background Technology

[0002] The water-gas shift (WGS) reaction describes the reaction in which carbon monoxide and water vapor form carbon dioxide and hydrogen: The reverse water-gas shift (RWGS) reaction is a reaction in the reverse direction, where carbon dioxide and hydrogen react to form carbon monoxide and water. Both WGS and RWGS reactions are in equilibrium. WGS equilibrium reactions are present in many applications, such as in the production of ammonia, hydrocarbons, methanol, and hydrogen. They are often combined with steam reforming of methane and other hydrocarbons. In the Fischer-Tropsch process, the WGS equilibrium reaction is one of the most important reactions used to balance the H2 / CO ratio. Additionally, the WGS equilibrium reaction has been combined with coal gasification to produce hydrogen. The petroleum and chemical industries require large quantities of hydrogen. For example, large amounts of hydrogen are used to upgrade fossil fuels and produce ammonia, methanol, or hydrochloric acid. Petrochemical plants require hydrogen for hydrocracking, hydrodesulfurization, and hydrodealkylation. Hydrogenation processes that increase the saturation of unsaturated fats and oils also require hydrogen. Hydrogen is also a reducing agent for metal ores.

[0003] Typically, WGS reactions are catalyzed by two classes of catalysts—high-temperature shift (HTS) catalysts and low-temperature shift (LTS) catalysts. HTS catalysts consist of iron oxide stabilized by chromium oxide; LTS catalysts are based on copper. Until now, WGS equilibrium reactions have been carried out chemically. Contrary to conventional practice, this disclosure discusses the unexpected discovery of electrochemically carried-out WGS reactions. Electrochemical reactors and methods for conducting such reactions are also discussed. Summary of the Invention

[0004] This article discusses an electrochemical reactor comprising an ion-conducting membrane, wherein the reactor electrochemically performs a water-gas shift reaction without electrical input, wherein the electrochemical water-gas shift reaction involves the exchange of ions through the membrane, and includes a forward water-gas shift reaction, a reverse water-gas shift reaction, or both.

[0005] In one embodiment, the reactor includes a porous electrode comprising a metallic phase and a ceramic phase, wherein the metallic phase is electronically conductive and the ceramic phase is ionicly conductive. In one embodiment, the electrode is separated from the membrane, and both are exposed to a reducing environment. In one embodiment, the electrode comprises Ni or NiO and materials selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, and combinations thereof.

[0006] In one embodiment, the ion-conducting membrane is impermeable to fluid flow. In one embodiment, the ion-conducting membrane also conducts electrons, and the reactor does not include interconnects. In one embodiment, the membrane comprises CGO. In one embodiment, the membrane comprises CoCGO. In one embodiment, the reactor comprises a catalyst that promotes a chemical reverse water-gas shift (RWGS) reaction. In one embodiment, the reactor also performs a chemical water-gas shift reaction.

[0007] This article also discusses a reactor comprising: a bifunctional layer and a hybrid conductive membrane; wherein the bifunctional layer and the hybrid conductive membrane are in contact with each other, and wherein the bifunctional layer catalyzes a reverse water-gas shift (RWGS) reaction and acts as an anode in the electrochemical reaction.

[0008] In one embodiment, the bifunctional layer serving as the anode is exposed to a reducing environment, and the electrochemical reaction occurring in the bifunctional layer is oxidation. In one embodiment, no current collector is attached to the bifunctional layer. In one embodiment, the reactor does not include interconnects, and the reactor does not receive or generate electricity. In one embodiment, the bifunctional layer comprises Ni or NiO and materials selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, and combinations thereof.

[0009] In one embodiment, the reactor includes a catalyst that promotes a chemical reverse water-gas shift (RWGS) reaction. In one embodiment, the catalyst is a high-temperature RWGS catalyst. In one embodiment, the catalyst is part of a bifunctional layer. In one embodiment, the catalyst is configured to be located on the outside of the bifunctional layer. In one embodiment, the catalyst includes Ni, Cu, Fe, Pt group metals, or combinations thereof.

[0010] Further aspects and embodiments are provided in the following figures, detailed description, and claims. Unless otherwise specified, the features described herein are combinable, and all such combinations are within the scope of this disclosure. Attached Figure Description

[0011] The following figures are provided to illustrate certain embodiments described herein. The figures are merely illustrative and are not intended to limit the scope of the claimed invention, nor are they intended to show every potential feature or embodiment of the claimed invention. The figures are not necessarily drawn to scale; in some cases, certain elements may be enlarged relative to other elements for illustrative purposes.

[0012] Figure 1 An electrochemical (EC) reactor or electrochemical gas generator according to embodiments of the present disclosure is shown.

[0013] Figure 2A A tubular electrochemical reactor according to an embodiment of the present disclosure is shown.

[0014] Figure 2B A cross-section of a tubular electrochemical reactor according to an embodiment of the present disclosure is shown.

[0015] Figure 3 A hydrogen generation system utilizing an EC reactor as discussed herein is shown according to embodiments of the present disclosure. Detailed Implementation

[0016] Overview

[0017] This disclosure describes an electrochemical WGS reactor and its usage. Various components of the reactor, such as electrodes and membranes, and the materials used in their construction are described. The following description sets forth various aspects and embodiments of the invention disclosed herein. Specific embodiments are not intended to limit 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. The description will be read from the perspective of one skilled in the art. Therefore, information known to one skilled in the art is not necessarily included.

[0018] Unless otherwise specified herein, the following terms and phrases shall have the following meanings. Other terms and phrases not expressly defined herein may be used in this disclosure. Such other terms and phrases shall have the meanings that a person skilled in the art would have in the context of this disclosure. In some cases, a term or phrase may be defined as singular or plural. In such cases, it should be understood that any term in its singular form may include its plural counterpart, and vice versa, unless expressly indicated to the contrary.

[0019] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” include plural indicators. For example, references to “substituent” cover a single substituent as well as two or more substituents. As used herein, “for example,” “such as,” or “comprising” are intended to introduce examples that further illustrate a more general subject matter. Unless otherwise clearly indicated, such examples are provided only to aid in understanding the embodiments described in this disclosure and are not intended to be limiting in any way. These phrases also do not indicate any kind of preference for the disclosed embodiments.

[0020] As used herein, compositions and materials are interchangeable 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.

[0021] As used herein, CGO refers to gadolinium-doped cerium dioxide, and is also alternatively referred to as gadolinium-doped cerium dioxide, gadolinium-doped cerium oxide, cerium oxide (IV), 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.

[0022] As used herein, cerium dioxide refers to cerium oxide, also known as cerium oxide (ceric oxide, cericdioxide, or cerium dioxide), which is an oxide of the rare earth metal cerium. Doped cerium dioxide refers to cerium dioxide doped with other elements, such as samarium-doped cerium dioxide (SDC) or gadolinium-doped cerium dioxide (GDC or CGO). As used herein, chromite refers to chromium oxide, which encompasses all oxidation states of chromium oxide.

[0023] As used herein, an impermeable layer or material is one that is impermeable to fluid flow. For example, an impermeable layer or material has a permeability of less than 1 microdarcy or less than 1 nanodarcy.

[0024] In this disclosure, sintering refers to a process in which solid material is formed by heating or pressing, or a combination thereof, without melting the material to the point of liquefaction. For example, material particles are agglomerated into a solid or porous material by heating, wherein atoms in the material particles diffuse across the boundaries of the particles, thereby causing the particles to fuse together and form a solid mass.

[0025] Interconnectors in electrochemical devices (e.g., fuel cells) are typically metallic or ceramic and are placed between the individual cells or repeaters. Their purpose is to connect each cell or repeater so that power can be distributed or combined. Interconnectors 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.

[0026] Electrochemistry, a branch of physical chemistry, deals with the relationship between electric potential as a measurable and quantifiable phenomenon and identifiable chemical changes, where the potential is a consequence of a particular chemical change, or vice versa. These reactions involve the movement of electrons between electrodes through a conductive phase (usually but not necessarily an external circuit), separated by an ion-conducting membrane and an electron-insulating membrane (or ionic species in solution). When a chemical reaction is affected by a potential difference, such as in electrolysis, or if the potential is generated by a chemical reaction in a battery or fuel cell, it is called an electrochemical reaction. Unlike chemical reactions, in electrochemical reactions, electrons (and the ions that are necessarily produced) do not transfer directly between molecules, but rather through the aforementioned electron-conducting and ion-conducting circuits, respectively. This phenomenon distinguishes electrochemical reactions from chemical reactions.

[0027] Contrary to conventional practice, an electrochemical reactor has been discovered comprising an ion-conducting membrane, wherein the reactor is capable of electrochemically performing a water-gas shift reaction, wherein the electrochemical water-gas shift reaction involves the exchange of ions through the membrane, and includes a forward water-gas shift reaction, a reverse water-gas shift reaction, or both. This differs from water-gas shift reactions via a chemical pathway, as chemical water-gas shift reactions involve the direct combination of reactants.

[0028] In one embodiment, the reactor includes a porous electrode comprising a metallic phase and a ceramic phase, wherein the metallic phase is electronically conductive and the ceramic phase is ionicly conductive. In various embodiments, the electrode has no current collector attached thereto. In various embodiments, the reactor contains no current collector. Clearly, this reactor is fundamentally different from any electrolysis device or fuel cell. In various embodiments, such reactors do not receive electricity or generate electricity.

[0029] In one embodiment, one of the electrodes in the reactor is an anode, which is configured to be exposed to a reducing environment while undergoing an oxidation reaction electrochemically. In various embodiments, the electrode comprises Ni or NiO and materials selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, and combinations thereof.

[0030] The electrochemical water-gas shift reaction occurring in the reactor includes an electrochemical half-cell reaction, wherein the half-cell reaction is:

[0031] 1.

[0032] 2.

[0033] In various embodiments, the half-cell reaction occurs at the three-phase boundary, which is the intersection of the pore with the electronically and ionicly conductive phases. Furthermore, the reactor is also capable of performing a chemical water-gas shift reaction.

[0034] In various embodiments, the ion-conducting membrane conducts protons or oxide ions. In various embodiments, the ion-conducting membrane comprises a solid oxide. In various embodiments, the ion-conducting membrane is impermeable to fluid flow. In various embodiments, the ion-conducting membrane also conducts electrons, and the reactor does not include interconnects.

[0035] This paper also discusses a reactor comprising a bifunctional layer and a hybrid conductive membrane; wherein the bifunctional layer and the hybrid conductive membrane are in contact with each other, and wherein the bifunctional layer catalyzes a reverse water-gas shift (RWGS) reaction and acts as an anode in the electrochemical reaction. In one embodiment, the bifunctional layer, serving as the anode, is exposed to a reducing environment, and the electrochemical reaction occurring in the bifunctional layer is oxidation. In one embodiment, no current collector is attached to the bifunctional layer. In one embodiment, the bifunctional layer comprises Ni or NiO and materials selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, and combinations thereof.

[0036] This reactor has a variety of applications. In one embodiment, the reactor is used to produce carbon monoxide by hydrogenating carbon dioxide. In another embodiment, the reactor is used to adjust the composition of syngas (i.e., the H2 / CO ratio) by converting H2 to CO or CO to H2. The following discussion uses hydrogen production as an example, but the applications of the reactor are not limited to hydrogen production.

[0037] Electrochemical reactor

[0038] Contrary to conventional practice, an electrochemical reactor has been discovered that includes a hybrid conductive membrane, in which the reactor is capable of electrochemically producing hydrogen from water without an electrical input. The electrochemical reaction involves the exchange of oxide ions through the membrane to oxidize a fuel (e.g., carbon monoxide). The hybrid conductive membrane also conducts electrons to complete the electrochemical reaction. Thus, the reactor does not include interconnects or bipolar plates. Furthermore, 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, this reactor is fundamentally different from any electrolysis device or any fuel cell.

[0039] Figure 1An electrochemical reactor or electrochemical (EC) gas generator 100 according to an embodiment of the present disclosure is shown. The electrochemical reactor (or EC gas generator) device 100 includes a first electrode 101, a membrane 103, and a second electrode 102. The first electrode 101 (also referred to as the anode) is configured to receive fuel 104. The feed stream 104 is oxygen-free. In this disclosure, the absence of oxygen means the absence of oxygen at the first electrode 101, or at least insufficient oxygen to interfere with the reaction. The second electrode 102 (also referred to as the cathode) is configured to receive water (e.g., steam), as indicated by 105.

[0040] In one embodiment, device 100 is configured to receive a feed stream 104 containing fuel (e.g., ammonia or syngas) and generate CO2 and / or H2O (106) at a first electrode (101). In various embodiments, the fuel includes H2, CO, syngas, ammonia, or combinations thereof. In one embodiment, device 100 is also configured to receive water or steam (105) and generate hydrogen (107) at a second electrode (102). In some cases, the second electrode receives a mixture of steam and hydrogen. Water is considered the oxidant in this case because it provides the oxide ions (transported via the membrane) required to oxidize the fuel (e.g., H2) at the opposite electrode. Thus, the first electrode 101 undergoes an oxidation reaction in a reducing environment, and the second electrode 102 undergoes a reduction reaction in a reducing environment. In various embodiments, 103 represents an oxide ion conductive membrane. In one embodiment, the oxide ion conductive membrane 103 also conducts electrons. Therefore, the membrane is mixed conductive.

[0041] In one embodiment, the first electrode 101 and the second electrode 102 comprise Ni-YSZ or NiO-YSZ. In various embodiments, electrodes 101 and 102 comprise Ni or NiO and materials selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, and combinations thereof. Alternatively, the hydrocarbon-containing gas is reformed before contacting the membrane 103 / electrode 101. The reformer is configured to perform steam reforming, dry reforming, or a combination thereof. The reformed gas is suitable as the feed stream 104.

[0042] In various embodiments, the device does not include a current collector. In one embodiment, the device does not include interconnects. No electricity is required, and this device is not an electrolyzer. This is a major advantage of the EC reactor of this disclosure. Membrane 103 is configured to conduct electrons, and is thus a hybrid conductor, i.e., both electronic and ionic conduction. In one embodiment, membrane 103 conducts oxide ions and electrons. In one embodiment, electrodes 101, 102 and membrane 103 are tubular (see, for example, [link to documentation]). Figure 2A and 2BIn one embodiment, electrodes 101, 102 and membrane 103 are planar. In these embodiments, the electrochemical reactions at the anode and cathode are spontaneous and do not require the application of a potential / electricity to the reactor.

[0043] In one embodiment, the electrochemical reactor (or EC gas generator) is a device comprising a first electrode, a second electrode, and a membrane between the electrodes, wherein the first and second electrodes comprise a metallic phase that is free of platinum group metals when the device is used, and wherein the membrane is oxide-ion conductive. In one embodiment, the first electrode is configured to hold fuel. In one embodiment, the fuel comprises ammonia or hydrogen or carbon monoxide or a combination thereof. In one embodiment, the second electrode is configured to hold water and hydrogen, and is configured to reduce water to hydrogen. In various embodiments, this reduction is carried out electrochemically without electrical input.

[0044] In one embodiment, the film includes an electronically conductive phase containing doped lanthanum chromate or an electronically conductive metal or combination thereof; and wherein the film includes an ionicly conductive phase containing a material selected from the group consisting of: gadolinium-doped cerium dioxide (CGO), samarium-doped cerium dioxide (SDC), yttrium-stabilized zirconium oxide (YSZ), strontium-magnesium-doped lanthanum gallium oxide (LSGM), scandium-stabilized zinc oxide (SSZ), Sc and Ce-doped zirconium oxide, and combinations thereof. In one embodiment, the doped lanthanum chromate includes strontium-doped lanthanum chromate, iron-doped lanthanum chromate, strontium and iron-doped lanthanum chromate, calcium lanthanum chromate, or combinations thereof; and wherein the conductive metal includes Ni, Cu, Ag, Au, Pt, Rh, or combinations thereof.

[0045] In one embodiment, the membrane comprises gadolinium-doped cerium dioxide, samarium-doped cerium dioxide, a sintering aid, or a combination thereof. In various embodiments, the sintering aid comprises divalent or trivalent transition metal ions, or a combination thereof. In one embodiment, the metal ion is an oxide. In one embodiment, the transition metal comprises Co, Mn, Fe, Cu, or a combination thereof. In one embodiment, the membrane comprises CGO. In one embodiment, the membrane comprises cobalt-doped CGO (CoCGO). In one embodiment, the membrane is substantially composed of CGO. In one embodiment, the membrane is composed of CGO. In one embodiment, the membrane is substantially composed of CoCGO. In one embodiment, the membrane is composed of CoCGO. In one embodiment, the reactor does not include interconnects.

[0046] Figure 2AA tubular electrochemical (EC) reactor or EC gas generator 200 according to an embodiment of the present disclosure is shown (not to scale). The tubular generator 200 includes an inner tubular structure 202, an outer tubular structure 204, and a membrane 206 disposed between the inner tubular structure 202 and the outer tubular structure 204. The tubular generator 200 further includes a void space 208 for a fluid passage. Figure 2B A cross-section of a tubular generator 200 according to an embodiment of the present disclosure is shown (not to scale). The tubular generator 200 includes a first inner tubular structure 202, a second outer tubular structure 204, and a membrane 206 between the inner tubular structure 202 and the outer tubular structure 204. The tubular generator 200 further includes a void space 208 for a fluid passage.

[0047] In one embodiment, the electrode and membrane are tubular, with the first electrode being the outermost and the second electrode being the innermost, wherein the second electrode is configured to collect water and hydrogen gas. In another embodiment, the electrode and membrane are tubular, with the first electrode being the innermost and the second electrode being the outermost, wherein the second electrode is configured to collect water and hydrogen gas. In yet another embodiment, the electrode and membrane are tubular.

[0048] In one embodiment, the reactor includes a catalyst that promotes a chemical reverse water-gas shift (RWGS) reaction. In one embodiment, the catalyst is a high-temperature RWGS catalyst. In one embodiment, the catalyst is part of the anode in the reactor. In one embodiment, the catalyst is configured to be located outside the anode. For example, Ni-Al2O3 particles are placed as such a catalyst in the reactor around the tubes, as... Figure 2A and Figure 2B As shown. In one embodiment, the catalyst comprises Ni, Cu, Fe, Pt group metals or combinations thereof. In another embodiment, the catalyst comprises Pt, Cu, Rh, Ru, Fe, Ni or combinations thereof.

[0049] Hydrogen generation systems and methods

[0050] This document discloses a method comprising: providing an apparatus including a first electrode, a second electrode, and a membrane between the electrodes; introducing a first feed stream to the first electrode; introducing a second feed stream to the second electrode; and extracting hydrogen from the second electrode, wherein the first and second electrodes comprise a metallic phase that does not contain platinum group metals when using the apparatus. In one embodiment, the membrane is oxide-ion conductive.

[0051] In one embodiment, the device operates at a temperature not lower than 500°C, or not lower than 600°C, or not lower than 700°C, or not lower than 750°C, or not lower than 800°C, or not lower than 850°C, or not lower than 900°C, or not lower than 950°C, or not lower than 1000°C. In various embodiments, the pressure difference between the first electrode and the second electrode is not greater than 2 psi, or not greater than 1.5 psi, or not greater than 1 psi. In one embodiment, the first feed stream enters the device at a pressure not greater than 10 psi, or not greater than 5 psi, or not greater than 3 psi. In one embodiment, the second feed stream enters the device at a pressure not greater than 10 psi, or not greater than 5 psi, or not greater than 3 psi.

[0052] In one embodiment, the first feed stream comprises fuel. In one embodiment, the fuel comprises hydrocarbons or hydrogen or carbon monoxide or ammonia or combinations thereof. In one embodiment, the first feed stream is introduced directly to a first electrode or a second feed stream is introduced directly to a second electrode or both. In one embodiment, the method includes providing a reformer or a catalytic partial oxidation (CPOX) reactor upstream of the first electrode, wherein the first feed stream passes through the reformer or CPOX reactor before being introduced to the first electrode, wherein the first electrode comprises Ni or NiO. In one embodiment, the reformer is a steam reformer or an autothermal reformer.

[0053] In one embodiment, the first feed stream comprises fuel. In one embodiment, the fuel comprises hydrocarbons or hydrogen or carbon monoxide or ammonia or a combination thereof. In one embodiment, the second feed stream consists of water and hydrogen. In one embodiment, the first feed stream comprises carbon monoxide and does not contain significant amounts of hydrogen or hydrocarbons or water. In such cases, an upstream reformer is not required. In this disclosure, "not significant amounts of hydrogen or hydrocarbons or water" means that the volume content of hydrogen or hydrocarbons or water is no more than 5%, or no more than 3%, or no more than 2%, or no more than 1%, or no more than 0.5%, or no more than 0.1%, or no more than 0.05%.

[0054] In various embodiments, the first feed stream comprises not less than 50% by volume of CO, or not less than 60% by volume of CO, or not less than 70% by volume of CO, or not less than 80% by volume of CO, or not less than 90% by volume of CO. In one embodiment, the first feed stream comprises CO2. In one embodiment, the first feed stream comprises syngas (CO and H2). In one embodiment, the first feed stream comprises an inert gas, such as argon or nitrogen. In one embodiment, the second feed stream consists of water and hydrogen.

[0055] In one embodiment, the method includes using the extracted hydrogen in one of the following: Fisher-Topsy (FT) reaction, dry reforming reaction, nickel-catalyzed Sabatier reaction, Bosch reaction, reverse water-gas shift reaction, electrochemical reaction that generates electricity, ammonia production, fertilizer production, electrochemical compressor for hydrogen storage, fueling of hydrogen vehicles, hydrogenation reaction, or a combination thereof.

[0056] In one embodiment, the first and second feed streams do not come into contact with each other in the device. In various embodiments, the reduction from water to hydrogen is carried out electrochemically without electrical input. In one embodiment, the first feed stream does not come into contact with hydrogen. In one embodiment, the first and second feed streams are separated by a membrane in the device.

[0057] In one embodiment, the fuel comprises hydrocarbons or hydrogen or carbon monoxide or ammonia or combinations thereof. In one embodiment, the second feed stream comprises hydrogen. In one embodiment, the first feed stream comprises fuel. In one embodiment, the fuel consists of carbon monoxide. In one embodiment, the first feed stream consists of carbon monoxide and carbon dioxide. In one embodiment, the second feed stream consists of water and hydrogen. In one embodiment, the second feed stream consists of steam and hydrogen.

[0058] like Figure 3 The diagram illustrates a hydrogen production system. The system includes a catalytic partial oxidation (CPOX) reactor 310; a steam generator 330; and an electrochemical (EC) reactor 320. The CPOX reactor product stream 323 is introduced into the EC reactor, and the steam generator supplies steam 321 to the EC reactor. The product stream 323 and steam 321 do not come into contact with each other in the EC reactor. The CPOX reactor product stream 323 is used as fuel in the EC reactor 320. The CPOX reactor 310 receives a stream 311 containing hydrocarbons (e.g., methane, ethane, propane, gasoline, jet fuel, etc.) and oxidizes the hydrocarbons to produce syngas, CO2, and water. Because the EC reactor can efficiently carry out the desired reaction in the presence of gases such as nitrogen, argon, and carbon dioxide, gas separation is not required between the CPOX reactor and the EC reactor. Furthermore, this allows the CPOX reactor to utilize air as an oxidant. While purified oxygen can always be used in the CPOX reactor, directly using air is significantly more economical in terms of both capital equipment costs and operating costs.

[0059] EC reactor 320 generates a first product stream 324 comprising CO and CO2 and a second product stream 322 comprising H2 and H2O, wherein the two product streams do not contact each other. In some cases, at least a portion (325) of the first product stream 324 is recycled to a steam generator to provide heat for generating steam from water. In some cases, a portion of the second product stream 322 is recycled to the EC reactor (on the cathode side, not shown). Figure 3 (in Chinese). In various embodiments, the EC reactor 320 includes an ion-conducting membrane that, together with the anode, enables the reactor to perform an electrochemical water-gas shift reaction, wherein the electrochemical water-gas shift reaction involves the exchange of ions through the membrane and includes a forward water-gas shift reaction, a reverse water-gas shift reaction, or both. The anode also enables the reactor to perform a chemical water-gas shift reaction.

[0060] Thus, hydrogen is generated by a method comprising: introducing hydrocarbons into a catalytic partial oxidation (CPOX) reactor to generate a product stream; and providing the product stream and vapor to an electrochemical (EC) reactor, wherein the product stream and vapor do not come into contact with each other in the EC reactor. The EC reactor includes an ion-conducting membrane, wherein the reactor is capable of electrochemically performing a water-gas shift reaction, wherein the electrochemical water-gas shift reaction involves the exchange of ions through the membrane, and includes a forward water-gas shift reaction, a reverse water-gas shift reaction, or both. Furthermore, the membrane separates the product stream from the vapor. In various embodiments, the pressure difference between the product stream side and the vapor side is no greater than 2 psi, or no greater than 1.5 psi, or no more than approximately 1 psi.

[0061] In various embodiments, the CPOX reactor uses air as the oxidant. In various embodiments, the CPOX reactor product stream enters the EC reactor directly without gas separation. In various embodiments, the EC reactor oxidizes the CPOX reactor product stream in a reducing environment to generate a first product stream comprising CO and CO2; and wherein the EC reactor electrochemically reduces steam to hydrogen without electrical input to generate a second product stream comprising H2 and H2O. In various embodiments, a membrane separates the first and second product streams. In various embodiments, at least a portion of the first product stream is used to generate steam from water. In various embodiments, at least a portion of the second product stream is recycled to enter the EC reactor.

[0062] A steam generator produces steam from water. In one embodiment, the temperature of the steam entering the electrochemical reactor is not lower than 600°C, or not lower than 700°C, or not lower than 800°C, or not lower than 850°C, or not lower than 900°C, or not lower than 950°C, or not lower than 1000°C, or not lower than 1100°C. In one embodiment, the pressure of the steam entering the electrochemical reactor is not greater than 10 psi, or not greater than 5 psi, or not greater than 3 psi.

[0063] It should be understood that this disclosure describes exemplary embodiments for carrying out different features, structures, or functions of the invention. Exemplary embodiments describing components, arrangements, and configurations are provided to simplify this disclosure; however, these exemplary embodiments are provided by way of example only and are not intended to limit the scope of the invention. Unless otherwise specified, the embodiments presented herein can be combined. Such combinations do not depart from the scope of this disclosure.

[0064] Furthermore, certain terms are used throughout the specification and claims to refer to specific components or steps. As will be understood by those skilled in the art, various entities may use different names to refer to the same components or process steps, and thus, the naming conventions of the elements described herein are not intended to limit the scope of the invention. Further, the terminology and naming conventions used herein are not intended to distinguish between components, features, and / or steps with different names but different functions.

[0065] While this disclosure is readily available in various modifications and alternative forms, specific embodiments thereof are shown by way of example in the accompanying drawings and description. It should be understood, however, that the drawings and detailed description are not intended to limit this disclosure to the particular forms disclosed, but rather, are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Claims

1. An electrochemical reactor comprising an ionically and electronically conductive membrane, wherein the membrane comprises CoCGO, wherein the reactor electrochemically performs a water-gas shift reaction without electrical input, wherein the electrochemical water-gas shift reaction involves the exchange of ions through the membrane and includes a forward water-gas shift reaction, or a reverse water-gas shift reaction, or both.

2. The reactor according to claim 1, comprising a porous electrode comprising a metallic phase and a ceramic phase, wherein the metallic phase is electronically conductive and wherein the ceramic phase is ionicly conductive.

3. The reactor of claim 2, wherein the electrodes are separated from the membrane and both are exposed to a reducing environment.

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

5. The reactor of claim 1, wherein the reactor does not include interconnects.

6. The reactor of claim 1, comprising a catalyst that promotes a chemical reverse water-gas shift (RWGS) reaction.

7. The reactor according to claim 1, wherein the reactor further performs a chemical water-gas shift reaction.

8. A reactor comprising: Dual-functional layers and hybrid conductive films; The membrane comprises CoCGO, the bifunctional layer and the hybrid conductive membrane are in contact with each other, and the bifunctional layer catalyzes the reverse water-gas shift (RWGS) reaction and acts as the anode in the electrochemical reaction.

9. The reactor of claim 8, wherein the bifunctional layer serving as the anode is exposed to a reducing environment, and the electrochemical reaction occurring in the bifunctional layer is oxidation.

10. The reactor of claim 8, wherein no current collector is attached to the bifunctional layer.

11. The reactor of claim 8, wherein the reactor does not include interconnects, and wherein the reactor does not receive electricity or generate electricity.

12. The reactor of claim 8, wherein the bifunctional layer comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM and combinations thereof.

13. The reactor of claim 8, comprising a catalyst that promotes a chemical reverse water-gas shift (RWGS) reaction.

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