Patent Application
20250011945
This disclosure generally relates to carbon monoxide (CO) production. More specifically, this disclosure relates to electrochemical carbon monoxide production.
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.
In the Fischer-Tropsch process, CO is an essential building block, which is often produced by converting carbon-rich feedstocks (e.g. coal). A mixture of CO and hydrogen (H2)—syngas—can combine to produce various fuels. Additionally, syngas are combined with olefins to produce aldehydes, which is called the hydroformylation process. The hydroformylation process is then used to produce many large scale chemicals such as surfactants as well as specialty compounds (e.g., fragrances and drugs). For example, CO is used in the production of vitamin A.
Clearly there is increasing need and interest to develop new technological platforms to produce carbon monoxide. This disclosure discusses CO production utilizing carbon dioxide via efficient electrochemical pathways. The electrochemical reactor and the method to perform such reactions are discussed.
Herein discussed is a method of producing carbon monoxide comprising: (a) providing an electrochemical reactor having an anode, a cathode, and a membrane between the anode and the cathode; (b) introducing a first stream to the anode, wherein the first stream comprises a fuel; (c) introducing a second stream to the cathode, wherein the second stream comprises carbon dioxide, and wherein carbon monoxide is generated from carbon dioxide electrochemically; wherein the reactor generates no electricity and receives no electricity; wherein the reactor is operated at a temperature no higher than 750° C. In an embodiment, the reactor is operated at a temperature no higher than 700° C. or no higher than 650° C.
In an embodiment, the first stream and the second stream do not come in contact with one another. In an embodiment, the fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, or combinations thereof. In an embodiment, the cathode exhaust is passed through a separator, wherein the generated carbon monoxide is separated from carbon dioxide. In an embodiment, the second stream comprises carbon monoxide, wherein the carbon monoxide is less than the carbon dioxide.
In an embodiment, the reactor comprises no interconnect and no current collector. In an embodiment, the anode and the cathode are both in contact with the membrane and are simultaneously exposed to reducing environments during the entire time of operation. In an embodiment, the reducing environments have an oxygen partial pressure of no greater than 1E-5 atm.
In an embodiment, the cathode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, CoCGO, and combinations thereof. In an embodiment, the anode comprises Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, SCZ, CoCGO, and combinations thereof. In an embodiment, the anode or the cathode comprises CGO or CoCGO or NiCGO. In an embodiment, the anode and the cathode have the same elements.
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 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 consist essentially of CoCGO or NiCGO.
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.
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 any claims and are not intended to show every potential feature or embodiment of the disclosed apparatuses, systems, and methods. 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.
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 axial cross section of the tubulars is shown to be circular, which is illustrative only and not limiting. The axial cross section of the tubulars is any suitable shape as known to one skilled in the art, such as square, square with rounded corners, rectangle, rectangle with rounded corners, triangle, hexagon, pentagon, oval, irregular shape, etc.
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 reactor 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 reactor 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 apparatuses, systems, and methods disclosed herein. No particular embodiment is intended to define or otherwise limit the scope of the disclosure. Rather, the embodiments provide non-limiting examples of various compositions and methods that are included within the scope of the disclosure and associated apparatuses, systems, and methods. 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.
Contrary to conventional practice, an electrochemical reactor has been discovered, which comprises an ionically conducting membrane, wherein the reactor is capable of reforming a hydrocarbon electrochemically or of performing water gas shift reactions electrochemically. The electrochemical reforming reactions involve the exchange of an ion through the membrane to oxidize the hydrocarbon. The electrochemical reactions involve the exchange of an ion through the membrane and include forward water gas shift reactions, or reverse water gas shift reactions, or both. These are different from traditional reforming reactions and water gas shift reactions via chemical pathways because they involve direct combination of reactants.
Traditional oxide ion membranes are operated at temperatures above 750° C. in order to have adequate performance and efficiency. Contrary to conventional wisdom, we have discovered a process wherein oxide ion membranes are utilized to produce carbon monoxide at a temperature no higher than 750° C. or no higher than 700° C. or no higher than 650° C. Such a process still has high performance and high efficiency.
In an embodiment, device 100 is configured to receive H2 (104) and to generate H2O (106) at the first electrode (101); device 100 is also configured to receive CO2 (105) and to generate CO (107) at the second electrode (102). In some case, the second electrode also receives a small amount of CO. Since CO2 provides the oxide ion (which is transported through the membrane) needed to oxidize the H2 at the opposite electrode, CO2 is considered the oxidant in this scenario. The reduction of CO2 produces CO. As such, the first electrode 101 is performing oxidation reactions in a reducing environment; the second electrode 102 is performing reduction reactions in a reducing environment. In some cases, such environments are considered nominally reducing environments. In various embodiments, the reducing environments have an oxygen partial pressure of no greater than LE-5 atm. In various embodiments, the reducing environments have an oxygen partial pressure of no greater than 1E-10 atm or no greater than 1E-15 atm.
In various embodiments, 103 represents an oxide ion conducting membrane. In an embodiment, the first electrode 101 and the second electrode 102 comprise Ni—YSZ or NiO—YSZ. In an embodiment, the oxide ion conducting membrane 103 also conducts electrons. In various embodiments, electrodes 101 and 102 comprise Ni or NiO and a material selected from the group consisting of YSZ, CGO, SDC, SSZ, LSGM, CoCGO, and combinations thereof. Alternatively, gases containing a hydrocarbon are reformed before coming into contact with the membrane 103/electrode 101. The reformer is configured to perform steam reforming, dry reforming, or combination thereof. The reformed gases are suitable as feed stream 104.
In this disclosure, no oxygen means there is no oxygen present at first electrode 101 or at least not enough oxygen that would interfere with the reaction. Also, in this disclosure, water only means that the intended feedstock is water and does not exclude trace elements or inherent components in water. For example, water containing salts or ions is considered to be within the scope of water only. Water only also does not require 100% pure water but includes this embodiment.
In various embodiments, the device does not contain a current collector. In an embodiment, the device comprises no interconnect. The device produces no electricity and thus is not a fuel cell. There is no need for electricity input and such a device is not an electrolyzer. This is a major advantage of the EC reactor of this disclosure. The membrane 103 is configured to conduct electrons and as such is mixed conducting, i.e., both electronically conductive and ionically conductive. In an embodiment, the membrane 103 conducts oxide ions and electrons. In an embodiment, the electrodes 101, 102 and the membrane 103 are tubular (see, e.g.,
In an embodiment, the electrochemical reactor (or EC gas producer) is a device comprising a first electrode, a second electrode, and a membrane between the electrodes, wherein the first electrode and the second electrode comprise a metallic phase that does not contain a platinum group metal when the device is in use, and wherein the membrane is oxide ion conducting. In an embodiment, the first electrode is configured to receive a fuel. In an embodiment, said fuel comprises ammonia, syngas, hydrogen, methanol, carbon monoxide, or combinations thereof. In an embodiment, the second electrode is configured to receive CO2 (with a small amount of CO) and configured to reduce the CO2 to CO. In various embodiments, such reduction takes place electrochemically.
In an embodiment, the anode or the cathode comprises CGO or CoCGO. In an embodiment, the anode and the cathode have the same elements. 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 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 consist essentially of CoCGO.
In an embodiment, the membrane consists essentially of CoCGO. In an embodiment, the anode and the cathode consist essentially of NiCGO.
In an embodiment, the electrodes and the membrane are tubular with the first electrode being outermost and the second electrode being innermost, wherein the second electrode is configured to receive CO2. In an embodiment, the electrodes and the membrane are tubular with the first electrode being innermost and the second electrode being outermost, wherein the second electrode is configured to receive CO2. In an embodiment, the electrodes and the membrane are tubular.
The electrochemical reactions taking place in the reactor comprise electrochemical half-cell reactions. In various embodiments, the half-cell reactions take place at triple phase boundaries, wherein the triple phase boundaries are the intersections of pores with the electronically conducting phase and the ionically conducting phase.
In various embodiments, the ionically conducting membrane conducts protons or oxide ions. In various embodiments, the ionically conducting membrane comprises solid oxide. In various embodiments, the ionically conducting membrane is impermeable to fluid flow. In various embodiments, the ionically conducting membrane also conducts electrons and wherein the reactor comprises no interconnect.
The EC reactor as discussed above is suitable to produce CO from CO2. In an embodiment, the reactor comprises porous electrodes that comprise metallic phase and ceramic phase, wherein the metallic phase is electronically conductive and wherein the ceramic phase is ionically conductive. In various embodiments, the electrodes have no current collectors attached to them. In various embodiments, the reactor does not contain any current collector. Clearly, such a reactor is fundamentally different from any electrolysis device or any fuel cell.
As illustrated in
A first stream 312 comprising a fuel is passed through the anode 301, becomes oxidized, and exits the anode as stream 313. A second stream 304 from CO2 source 312 is passed through the cathode 302, wherein CO2 is reduced to CO. Cathode exhaust stream 305 is passed through the separator 341, wherein CO is separated from CO2. Product stream 342 exits the separator 341 and consists essentially of CO. A portion of stream 305 or of stream 342 may be recycled to the anode 302 (not shown in
The process and system of CO production according to this disclosure have various advantages. CO generation from CO2 is desirable because it reduces greenhouse gas emission. Making CO locally (on site) is inherently safer than transporting CO in pressurized containers or vessels. The process of this disclosure utilizes efficient electrochemical pathways but yet needs no electricity. The CO/CO2 separation from the cathode exhaust is easy and inexpensive. As such, the method and system of this disclosure are cost competitive both in capital equipment and in operational expenses.
It is to be understood that this disclosure describes exemplary embodiments for implementing different features, structures, or functions of the disclosed apparatuses, systems, and methods. 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 apparatuses, systems, and methods disclosed herein. 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 apparatuses, systems, and methods disclosed herein. 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.
This application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application No. 63/512,225 filed Jul. 6, 2023, the entire disclosure of which is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63512225 | Jul 2023 | US |
