Catalyst Revitalization for Oxocarbon Electrolyzer

Abstract

Method for operating an oxocarbon electrolysis reactor are disclosed. A disclosed method includes supplying a cathode area of the oxocarbon electrolysis reactor with an oxocarbon species as a reduction substrate for a reduction reaction. The reduction reaction uses a catalyst in the cathode area of the oxocarbon electrolysis reactor. The method also includes supplying an anode area of the oxocarbon electrolysis reactor with an oxidation substrate for an oxidation reaction. The method also includes valorizing the oxocarbon species into a useful species in a valorization process. The valorization process includes the reduction reaction and the oxidation reaction. The method also includes supplying an oxidant to the cathode area of the oxocarbon electrolysis reactor, whereby the oxidant revitalizes the catalyst.

Claims

1. A method for operating an oxocarbon electrolysis reactor comprising: supplying a cathode area of the oxocarbon electrolysis reactor with an oxocarbon species as a reduction substrate for a reduction reaction; supplying an anode area of the oxocarbon electrolysis reactor with an oxidation substrate for an oxidation reaction; valorizing the oxocarbon species into a useful species via a valorization process, wherein the valorization process includes the reduction reaction and the oxidation reaction; monitoring a performance of the valorization process in a monitoring process; and supplying an oxidant to the cathode area of the oxocarbon electrolysis reactor in a revitalization process for a catalyst of the oxocarbon electrolysis reactor conducted in response to a change in the performance of the valorization process as monitored in the monitoring process; wherein the oxocarbon electrolysis reactor is a carbon monoxide electrolysis reactor and the oxidant is one of: air, O.sub.2, O.sub.3, H.sub.2, Cl.sub.2, H.sub.2O.sub.2, Br.sub.2, I.sub.2, F.sub.2, and H.sub.2S.sub.2O.sub.8.

2. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the revitalization process comprises: shutting down the oxocarbon electrolysis reactor; and supplying the oxidant to the cathode area while the oxocarbon electrolysis reactor is shut down.

3. The method for operating an oxocarbon electrolysis reactor of claim 2, wherein the revitalization process comprises: pressurizing the cathode area to a pressure while the oxidant is in the cathode area.

4. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the revitalization process is conducted in response to the change in performance in that: the revitalization process is triggered upon detecting a decrease in the performance of the valorization process.

5. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the revitalization process comprises: supplying the oxidant to the cathode area while the oxocarbon electrolysis reactor is operational and conducting the valorization process.

6. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the revitalization process is conducted in response to the change in performance in that: the revitalization process supplies an increased amount of the oxidant in response to detecting the performance has decreased.

7. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the revitalization process is conducted in response to the change in performance in that: the revitalization process supplies an increased amount of the oxidant in response to detecting the performance has decreased in a manner correlated to the supplying of the oxidant; and the revitalization process supplies a decreased amount of the oxidant in response to detecting the performance has decreased in a manner uncorrelated to the supplying of the oxidant.

8. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the monitoring process comprises: monitoring a selectivity of the oxocarbon electrolysis reactor for the useful species; wherein the performance is the selectivity.

9. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the monitoring process comprises: monitoring an electrical parameter of the oxocarbon electrolysis reactor; wherein the performance is derived from the electrical parameter.

10. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein the catalyst: is one of a metal ion and a metal; and includes at least one element from a group consisting of: Cu, Ag, Au, Zn, Sn, Bi, Ni, Fe, Co, Pd, Ir, Pt, Mn, Re, Ru, La, Tb, Ce, and Dy.

11. The method for operating an oxocarbon electrolysis reactor of claim 1, wherein: the cathode area is a gaseous phase reactor area; the cathode area includes a gas diffusion layer; the catalyst is on the gas diffusion layer; and the oxidant is supplied to the oxocarbon electrolysis reactor in gaseous form.

12. The method for operating an oxocarbon electrolysis reactor of claim 3, wherein: the pressure is at least 1.1 bar.

13. The method for operating an oxocarbon electrolysis reactor of claim 3, wherein: the pressure is applied to the cathode area for at least 5 minutes.

14. A method for operating an oxocarbon electrolysis reactor comprising: supplying a cathode area of the oxocarbon electrolysis reactor with an oxocarbon species as a reduction substrate for a reduction reaction, wherein the reduction reaction uses a catalyst in the cathode area of the oxocarbon electrolysis reactor; supplying an anode area of the oxocarbon electrolysis reactor with an oxidation substrate for an oxidation reaction; valorizing the oxocarbon species into a useful species in a valorization process, wherein the valorization process includes the reduction reaction and the oxidation reaction; and supplying an oxidant to the cathode area of the oxocarbon electrolysis reactor in a revitalization process, whereby the oxidant revitalizes the catalyst; wherein the oxocarbon electrolysis reactor is a carbon monoxide electrolysis reactor and the oxidant is one of: air, O.sub.2, O.sub.3, H.sub.2, Cl.sub.2, H.sub.2O.sub.2, Br.sub.2, I.sub.2, F.sub.2, and H.sub.2S.sub.2O.sub.8.

15. The method for operating an oxocarbon electrolysis reactor of claim 14, wherein the oxidant is supplied to the cathode area in a revitalization process and the revitalization process comprises: shutting down the oxocarbon electrolysis reactor; and supplying the oxidant to the cathode area while the oxocarbon electrolysis reactor is shut down.

16. The method for operating an oxocarbon electrolysis reactor of claim 15, wherein the revitalization process comprises: pressurizing the cathode area to a pressure of at least 1.1 bar while the oxidant is in the cathode area.

17. The method for operating an oxocarbon electrolysis reactor of claim 14, further comprising: supplying the oxidant to the cathode area while the oxocarbon electrolysis reactor is operational and conducting the valorization process.

18. The method for operating an oxocarbon electrolysis reactor of claim 14, wherein the oxidant is supplied to the cathode area in a revitalization process and the revitalization process comprises: removing a fouling agent from the catalyst using the oxidant; and regenerating a catalytic performance of the catalyst to within 5% of an original performance of the catalyst.

19. The method for operating an oxocarbon electrolysis reactor of claim 14, wherein the oxidant is supplied to the cathode area in a revitalization process and the revitalization process comprises: oxidizing the catalyst; and regenerating a catalytic performance of the catalyst to within 5% of an original performance of the catalyst.

20. The method for operating an oxocarbon electrolysis reactor of claim 14, wherein the catalyst: is one of a metal ion and a metal; and includes at least one element from a group consisting of: Cu, Ag, Au, Zn, Sn, Bi, Ni, Fe, Co, Pd, Ir, Pt, Mn, Re, Ru, La, Tb, Ce, and Dy.

21. The method for operating an oxocarbon electrolysis reactor of claim 14, wherein: the cathode area is a gaseous phase reactor area; the cathode area includes a gas diffusion layer; the catalyst is on the gas diffusion layer; and the oxidant is supplied to the oxocarbon electrolysis reactor in gaseous form.

22. The method for operating an oxocarbon electrolysis reactor of claim 16, wherein: the pressure is at least 1.1 bar.

23. The method for operating an oxocarbon electrolysis reactor of claim 16, wherein: the pressure is applied to the cathode area for at least 5 minutes.

24. A method for operating an oxocarbon electrolysis reactor comprising: supplying a cathode area of the oxocarbon electrolysis reactor with an oxocarbon species as a reduction substrate for a reduction reaction; supplying an anode area of the oxocarbon electrolysis reactor with an oxidation substrate for an oxidation reaction; valorizing the oxocarbon species into a useful species in a valorization process, wherein the valorization process includes the reduction reaction and the oxidation reaction; and supplying an oxidant to the cathode area of the oxocarbon electrolysis reactor in a revitalization process for a catalyst of the oxocarbon electrolysis reactor, wherein the revitalization process comprises: (i) shutting down the oxocarbon electrolysis reactor; (ii) supplying the oxidant to the cathode area while the oxocarbon electrolysis reactor is shut down; and (iii) pressurizing the cathode area to a pressure while the oxidant is in the cathode area; wherein the oxocarbon electrolysis reactor is a carbon monoxide electrolysis reactor and the oxidant is one of: air, O.sub.2, O.sub.3, H.sub.2, Cl.sub.2, H.sub.2O.sub.2, Br.sub.2, I.sub.2, F.sub.2, and H.sub.2S.sub.2O.sub.8.

25. The method for operating an oxocarbon electrolysis reactor of claim 24, wherein: the pressure is at least 1.1 bar.

26. The method for operating an oxocarbon electrolysis reactor of claim 24, wherein: the pressure is applied to the cathode area for at least 5 minutes.

27. The method for operating an oxocarbon electrolysis reactor of claim 24, further comprising: monitoring a performance of the valorization process in a monitoring process; wherein the oxidant is supplied to the cathode area in the revitalization process in response to a change in the performance of the valorization process as monitored in the monitoring process.

28. The method for operating an oxocarbon electrolysis reactor of claim 27, wherein the monitoring process comprises: monitoring a selectivity of the oxocarbon electrolysis reactor for the useful species; wherein the performance is the selectivity.

29. The method for operating an oxocarbon electrolysis reactor of claim 24, wherein the catalyst: is one of a metal ion and a metal; and includes at least one element from a group consisting of: Cu, Ag, Au, Zn, Sn, Bi, Ni, Fe, Co, Pd, Ir, Pt, Mn, Re, Ru, La, Tb, Ce, and Dy.

30. The method for operating an oxocarbon electrolysis reactor of claim 24, wherein: the cathode area is a gaseous phase reactor area; the cathode area includes a gas diffusion layer; the catalyst is on the gas diffusion layer, and the oxidant is supplied to the oxocarbon electrolysis reactor in gaseous form.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the disclosure. A person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another and vice versa. Furthermore, elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.

[0022] FIG. 1 illustrates an oxocarbon electrolysis reactor that can be utilized in accordance with specific embodiments of the inventions disclosed herein.

[0023] FIG. 2 includes an example of a reactor for generating ethylene in operation mode, in accordance with specific embodiments of the inventions disclosed herein.

[0024] FIG. 3 includes an illustration of an example of a reactor being shut down and an oxidant introduced in reactive mode, in accordance with specific embodiments of the inventions disclosed herein.

[0025] FIG. 4 includes an example of the reactor being fed oxidant along with the reduction substrate, in accordance with specific embodiments of the inventions disclosed herein.

[0026] FIG. 5 includes an example of the reactor being fed oxidant along with the reduction substrate where the oxidant is oxygen produced at the anode, in accordance with specific embodiments of the inventions disclosed herein.

[0027] FIG. 6 includes a flowchart for a method of catalyst revitalization for an oxocarbon electrolyzer, in accordance with specific embodiments of the inventions disclosed herein.

[0028] FIG. 7 illustrates a flow chart for a method of catalyst revitalization in response to a decrease in the performance of the valorization process in accordance with specific embodiments of the inventions disclosed herein.

[0029] FIGS. 8A and 8B illustrate the performance of catalyst regeneration by air flushing the cathode area, in accordance with specific embodiments of the inventions disclosed herein.

[0030] FIG. 8C illustrates the performance of a catalyst in a control experiment where an oxidant is not introduced to the cathode area.

[0031] FIG. 9 includes SEM observations and accompanying EDX analysis results of metal contamination at the cathode, to illustrate the mechanism by with specific embodiments of the inventions disclosed herein operate.

DETAILED DESCRIPTION

[0032] Reference will now be made in detail to implementations and embodiments of various aspects and variations of systems and methods described herein. Although several exemplary variations of the systems and methods are described herein, other variations of the systems and methods may include aspects of the systems and methods described herein combined in any suitable manner having combinations of all or some of the aspects described.

[0033] Methods and systems related to catalysts used in oxocarbon electrolysis reactors in accordance with the summary above are disclosed in detail herein. The methods and systems disclosed in this section are nonlimiting embodiments of the invention, are provided for explanatory purposes only, and should not be used to constrict the full scope of the invention. It is to be understood that the disclosed embodiments may or may not overlap with each other. Thus, part of one embodiment, or specific embodiments thereof, may or may not fall within the ambit of another, or specific embodiments thereof, and vice versa. Different embodiments from different aspects may be combined or practiced separately. Many different combinations and sub-combinations of the representative embodiments shown within the broad framework of this invention, that may be apparent to those skilled in the art but not explicitly shown or described, should not be construed as precluded.

[0034] The electrolyzers used in accordance with the approaches disclosed herein can have various architectures. The electrolyzer can include an anode area and a cathode area. The anode area and the cathode area can each either be aqueous phase reactor areas or gaseous phase reactor areas. An oxocarbon can be provided to the cathode area of the reactor as a reduction substrate in liquid or gaseous form. Useful species can be produced in the cathode area, in the anode area, or in a separating area located between the cathode area and the anode area of the electrolyzer. The rate at which the reaction occurs can be dependent upon the performance of one or more catalysts in the reactor. The catalysts can be anode catalysts, cathode catalysts, or both. The electrolyzer can be a single planar electrolyzer. The electrolyzer can be a stack of cells. The cells in the stack can utilize bipolar plates. The bipolar plates can be charged to initiate reactions within the reactor. The electrolyzer can also be a filter press electrolyzer or a tubular electrolyzer.

[0035] The electrolyzers used in accordance with this disclosure can comprise one or more electrocatalytic cells positioned on top or next to one another to increase the surface available for the reaction. They can be stacked on top of one another, and such stacks can also be parallelized. These cells may be connected in series or in parallel. Many different cell and stack configurations can be used for the electrolyzers in accordance with this disclosure.

[0036] FIG. 1 includes an electrolyzer 100 that can be utilized in accordance with specific embodiments of the inventions disclosed herein for explanatory purposes. The methods and systems disclosed herein are broadly applicable to oxocarbon electrolyzers generally and electrolyzer 100 is provided as a nonlimiting example of one such electrolyzer.

[0037] FIG. 1 includes an illustration of an electrolyzer 100 in the form of a stack in accordance with specific embodiments of the inventions disclosed herein. The electrolyzer 100 includes end plates such as end plate 102, monopolar plates such as monopolar plate 104, rigid bars such as rigid bar 106, a separator and electrode assembly such as assembly 108, a flow field such as flow field 110, and bipolar plates such as bipolar plate 112. The assembly 108 can include two electrodes (the cathode and the anode) and a separator 130 between the two electrodes. Additionally, the electrolyzer 100 includes an inlet 114 and an outlet 116 for an anodic stream, as well as an inlet 118 for a cathodic stream and an outlet 120 for the cathodic stream. An oxocarbon can be provided at the inlet 118 in the cathodic stream. The oxocarbon can be humidified. A useful species can be provided at outlet 116 in the anodic stream or at outlet 120 in the cathodic stream. The polar plates, such as monopolar plate 104 and bipolar plate 112 can be part of the cells in the stack. The stack can also comprise gasketing, sealing of any shape, insulating layers, and other materials that have not been represented in the FIG. 1 for clarity.

[0038] In an electrolysis stack, subsequent cells can be physically separated by bipolar plates (BPPs), such as bipolar plate 112 in FIG. 1, which can ensure mechanical support for each of the electrolysis cells on each side of the BPP. BPP can also ensure an electrical series connection between subsequent electrolysis cells and introduce/remove the reactants/products respectively. At the end of the stack, only one side of the plate can be in contact with the terminal cell: it is then called a monopolar plate, such as monopolar plate 104 in FIG. 1. At the extremities of the stack, current collectors can allow connection to an external power supply, which can also be used, among other elements, for electrical monitoring of the stack. The stack can be assembled within a stack casing allowing its mechanical support and compression, as well as provisioning and transporting the reactant and product streams to and from the stack. The stack casing can comprise end plates that ensure electrical isolation of the stack and provide the inlet and outlets for the reactant and product streams. Alternatively, insulator plates can be placed between the end plate such as end plate 102, and the monopolar plate such as monopolar plate 104 to ensure electrical insulation of the stack versus the stack casing depending on the material of the end plate.

[0039] The oxocarbon electrolyzers can take as an input, a cathodic input stream (e.g., a stream enriched in carbon monoxide or carbon dioxide), and an anode input stream. In such cases, the reduction substrate is carbon monoxide or carbon dioxide. The cathodic input stream can be provided to an inlet such as inlet 118. The anodic input stream can be provided to an inlet such as inlet 114. The cathodic stream and anodic stream can flow through the stack from the inlets to the outlets and be distributed through the flow channels, such as those in flow field 110 of each cell to each cathodic and anode area separately. The anodic stream and cathodic stream would flow through separate channels on either side of the cell. Alternatively, at least one of the cathodic and anodic streams may be provided to each cell individually instead of through a connection crossing all the plates. In this case, each cell has a dedicated fluid inlet and outlet for this cathodic and/or anodic stream. The nature of the anodic stream can be determined by the nature of the targeted oxidation reaction (such as, but not limited to, water oxidation, dihydrogen oxidation, chloride oxidation, halide oxidation, hydrocarbon oxidation, and waste organic oxidation). For example, the generating of chemicals using carbon monoxide and the electrolyzer could involve supplying the volume of carbon monoxide to a cathode area of the electrolyzer as a cathodic input fluid and supplying a volume of water to an anode area of the electrolyzer as an anodic input fluid. When electrically powered, the carbon monoxide electrolyzer carries out the concomitant reduction of carbon monoxide and oxidation of the chosen oxidation substrate to produce useful species such as hydrocarbons, organic acids and/or alcohols, and/or N-containing organic products in the anodic stream.

[0040] FIG. 2 includes an example of a reactor for generating ethylene. In one example, an oxocarbon electrolysis reactor 200 is composed of a cathode area 201 comprising a gas-diffusion layer and a copper-based carbon-oxide-reduction catalyst. The anode area 202 comprises a catalyst with at least one of Ir, Co, Cu, Ni, Fe, Pt, Rh, Re, Ru, Pd, Os, and Mo supported by a porous metal-based support of any shape (such as but not limited to a foam, a mesh, or a conductive porous transport layer (PTL)). The metal of the metal-based support could be titanium-based, nickel-based, or be based on any other metal mentioned herein for this purpose. In this case, the reduction products include one or more of the following: ethylene (C.sub.2H.sub.4), ethanol (C.sub.2H.sub.5OH), acetic acid (C.sub.2H.sub.3COOH), propylene (C.sub.3H.sub.6), and propanol (C.sub.3H.sub.8O).

[0041] When operating, the oxocarbon electrolysis reactor 200 can be fed a stream of humidified carbon oxide gas humified by the humidifier 203 to the cathode area 201 side of the oxocarbon electrolysis reactor 200, and an aqueous stream is fed to the anode area 202. In alternative embodiments, the humidifier is removed, and the reactor receives a stream of oxocarbon without an appreciable amount of water vapor. A voltage is applied across the reactor that facilitates the carbon-oxide reduction reaction at the cathode area 201 and complimentary oxidation reaction at the anode area 202, this is referred to as the operation mode in FIG. 2. Continuous analysis of the product stream of the cathode area 201 is carried out, which confirms the production of the desired species, for example, ethylene. A gas separator 204 is employed at the outlet, such as but not limited to, a pressure swing adsorption column or a membrane-based separator, to remove the unreacted carbon oxide from the ethylene. The unreacted carbon oxide can then be fed back to the cathode area 201 inlet. At the anode area 202, produced oxygen from the oxidation of water is separated from water through a gas-liquid separator 205.

[0042] FIG. 3 includes an illustration of an example with oxocarbon electrolysis reactor 300 being shut down and oxidant introduced in accordance with specific embodiments of the inventions disclosed herein. Oxocarbon electrolysis reactor 300 can be the same reactor as in FIG. 2, but with the reactor shut down. After several hours of continuous operation of an oxocarbon electrolysis reactor, a drop in selectivity for a desired species may be observed, which is a result of the cathode catalyst becoming deactivated for the desired conversion reaction. For example, in FIG. 2 the desired species is ethylene and selectivity of the reactor can be measured by how much ethylene is produced for unit of oxocarbon input. At the point where a drop in selectivity is detected, the applied voltage across the cell can be either lowered to drastically decrease the electrolysis current or stopped entirely. Subsequently, an oxidant can be fed to the cathode area, such as, but not limited to air, O.sub.2, O.sub.3, H.sub.2, HNO.sub.3, Cl.sub.2, H.sub.2O.sub.2, Br.sub.2, I.sub.2, F.sub.2, H.sub.2S.sub.2O.sub.8, and H.sub.2SO.sub.4. This period is referred to as the reactivation mode as it is in this mode that the catalyst is refreshed and reactivated. In specific embodiments, the oxidant is generated by the oxidation reaction which took place in the anode area 302 when the oxocarbon electrolysis reactor 300 was in the operation mode (e.g., the oxygen produced at the anode in FIG. 2).

[0043] Introduction of the oxidant to the cathode area leads to the reactivation of the cathode area 301 catalyst. This reactivation occurs throughout a predetermined amount of time in which the oxidant is introduced (e.g., 10 minutes). In specific embodiments of the invention, the oxidant is supplied in a concentration of at least 0.01 M for at least 5 minutes. Following this reactivation, the electrolyzer is reverted to operation mode, where the catalytic activity resumes a level similar to that at the beginning of the electrolyzer operation.

[0044] FIG. 4 includes an example of an oxocarbon electrolysis reactor 400 being fed oxidant along with the reduction substrate. The presence of the oxidant leads to the continued stability of the cathodic catalyst (e.g., a copper catalyst) by preventing its deactivation. The quantity of oxidant fed to the cathode area may be lowered or increased depending on the observed decreases in the production of the desired product, in this case, ethylene.

[0045] In another embodiment of the invention, the oxidant is fed constantly alongside the oxocarbon in a proportion at which the reductive catalyst maintains its selectivity of oxocarbon conversion to the desired products. This avoids the need to remove the voltage of the electrolyzer and the need for an explicit reactivation stage. As a result, the reactor can produce useful products continuously, and no time is wasted transitioning the reactor through different modes of operation.

[0046] In one example, an oxocarbon electrolysis reactor 400 is composed of a cathode area 401 comprising a gas-diffusion layer and a copper-based carbon-oxide-reduction catalyst. The anode area 402 comprises a catalyst with at least one of Ir, Co, Cu, Ni, Fe, Pt, Rh, Re, Ru, Pd, Os, and Mo supported by a porous metal-based support of any shape (such as but not limited to a foam, a mesh, or a conductive PTL). The metal of the metal-based support could be titanium-based, nickel-based, or be based on any other metal mentioned herein for this purpose. In this case, the reduction products include one or more of the following: ethylene (C.sub.2H.sub.4), ethanol (C.sub.2H.sub.5OH), acetic acid (C.sub.2H.sub.3COOH), propylene (C.sub.3H.sub.6), propanol (C.sub.3H.sub.8O).

[0047] When operating, the oxocarbon electrolysis reactor 400 is fed a stream of humidified carbon oxide gas humified by the humidifier 403 along with an oxidant on the cathode area 401 side of the oxocarbon electrolysis reactor 400, and an aqueous stream is fed to the anode area 402. A voltage is applied across the reactor that facilitates the carbon-oxide reduction reaction at the cathode area 401 and complimentary oxidation reaction at the anode area 402, this is referred to as the operation mode. Continuous analysis of the product stream of the cathode area 201 is carried out, which confirms the production of the desired species, for example, ethylene. A gas separator 404 is employed at the outlet, such as but not limited to, a pressure swing adsorption column or a membrane-based separator, to remove the unreacted carbon oxide from the ethylene. The unreacted carbon oxide can then be fed back to the cathode area 401 inlet. At the anode area 402, produced oxygen from the oxidation of water is separated from water through a gas-liquid separator 405.

[0048] FIG. 5 includes an example of an oxocarbon electrolysis reactor 500 being fed oxidant along with the reduction substrate where the oxygen is produced at the anode area 502. During operation, a small proportion of the oxidant, for example, oxygen, produced at the anode area 502 is fed to the cathodic stream in a constantly regulated flow. Accordingly, the oxocarbon electrolysis reactor 500 is composed of a cathode area 501 comprising a gas-diffusion layer and a copper-based carbon-oxide-reduction catalyst. The anode area 502 has a catalyst comprising at least one of Ir, Co, Cu, Ni, Fe, Pt, Rh, Re, Ru, Pd, Os, and Mo supported by a porous metal-based support of any shape (such as but not limited to a foam, a mesh, or a conductive (PTL)). The metal of the metal-based support could be titanium-based, nickel-based, or be based on any other metal mentioned herein for this purpose. In this case, the reduction products include one or more of the following: ethylene (C.sub.2H.sub.4), ethanol (C.sub.2H.sub.5OH), acetic acid (C.sub.2H.sub.3COOH), propylene (C.sub.3H.sub.6), propanol (C.sub.3H.sub.8O).

[0049] When operating, the oxocarbon electrolysis reactor 500 is fed at the cathode area 501 with a stream of humidified carbon-oxide gas, humified by a humidifier 503 along with a portion of oxidant from the anode area 502, and an aqueous stream is fed to the anode area 502. A voltage is applied across the oxocarbon electrolysis reactor 500 that facilitates the carbon-oxide reduction reaction at the cathode area 501 and a complimentary oxidation reaction at the anode area 502. A gas separator 504 is employed at the outlet, such as but not limited to, a pressure swing adsorption column or a membrane-based separator, to remove the unreacted carbon oxide from the ethylene. The unreacted carbon oxide can then be fed back to the cathode inlet. At the anode area 502, produced oxygen from the oxidation is separated from water through a gas-liquid separator 505.

[0050] FIG. 6 includes a schematic view of a method 600 method for operating an oxocarbon electrolysis reactor, such as electrolyzer 100 of FIG. 1, for converting CO.sub.x (such as CO.sub.2 and CO) into desired chemicals. The method 600 includes a step 601 of supplying an oxocarbon species to cathode. The method 600 further includes the step of supplying an oxidation substrate to anode 602. The method 600 further includes valorising the oxocarbon specie into a useful species 603. Further, the method comprises the step of monitoring a performance of the valorisation process 604. Upon monitoring and observing that the performance of the valorisation is reduced, the method can continue to revitalization by supplying an oxidant to the cathode in response to a change in the performance of the valorization process as monitored in the monitoring process. These actions can be taken to modify an operational state of the system or part of the system, such as of a cell or group of cells. The method 600 represents an overview of the steps that can be taken depending on the desired outcome. Details and examples of realizations of the methods for operating an oxocarbon electrolysis reactor outlined in FIG. 6 will be given as appended below.

[0051] FIG. 7 includes a flow chart 700 that further illustrates revitalization in response to a decrease in the performance of the valorisation process 605. The revitalization of the electrolysis reactor is performed in different ways based on a number of factors. One of the ways is based on the oxidant characteristic. If the oxidant is a gas, the oxidant can be oxygen generated and supplied from the anode as in 605a or an oxidant supplied from an oxidant source as in 605ab. In specific embodiments of the invention in accordance with 605a, the oxidant introduced into the reactor originates from the anodic reaction stream of the electrolyzer. The anodic reaction of electrolysis can be the oxidation of water to oxygen, which may serve as a pure stream of oxidant with which to reactivate the catalyst.

[0052] In another embodiment of the invention, if the oxidant is a liquid, such as a dilute solution containing hydrogen peroxide or nitric acid, then the oxidant is injected into the electrolyzer in place of the carbon-oxide containing fluid line where it can serve as an oxidant-as disclosed in step 605b.

[0053] Further, the revitalization of the electrolysis reactor process can be based on if the oxidant is supplied when the reactor is operational or when the reactor is temporarily stopped. In some embodiments, where the reactor is temporarily stopped, the process can include shutting down the oxocarbon electrolysis reactor in a step 605ca, then supplying the oxidant to the cathode area in a step 605cb. Further, the process can include pressurizing the cathode area 605cc to a pressure while the oxidant is in the cathode area. In specific embodiments, the pressure can be at least 1.1 bar to produce an improvement in the revitalization of the catalyst. In some embodiments, where the reactor is not stopped, the process can occur while the reactor is operational in a step 605d, the application of the oxidant can be continuous as in step 605da or variable as in step 605db.

[0054] The variable application of the oxidant can be conducted in various ways. The oxidant can be applied in a binary on/off manner at different times or in a continuous stream along with the reduction substrate with variable conditions such as the amount of oxidant supplied, temperature of the cathode area, or pressure of the cathode area. The variations can be conducted in an open loop manner in accordance with a fixed schedule or in a close loop manner in response to a measured parameter of operation.

[0055] If the process is intermittent as in step 605db1 (either in terms of the oxidant only being supplied during a temporary break or the intensity of a continuously supplied stream varying), the period between applications, or the intensity of applications can be adjustable. Further, the oxidant can be supplied as part of a default shutdown or startup procedure 605db2, or a combination of both 605db3. For example, apply a small amount of oxidant could be applied continuously during operation and then a heavier application could be applied during a temporary stop.

[0056] Further, the revitalization can be performed based on a fixed schedule for the application of oxidant or by monitoring the fouling of the catalyst at the cathode. When the adjustment is based on a fixed schedule, it is termed as open loop control as in step 605e. The intensity of a continuous stream can be adjusted based on a fixed schedule. The periodicity of a periodically applied stream can also be adjusted based on a fixed schedule. The parameters for the oxidant supply such as the temperature and pressure can also be adjusted based on a fixed schedule.

[0057] When the application of oxidant is based on monitoring performance, it is termed as closed-loop control as in step 605f. The parameters of the process are adjusted based on monitoring performance, wherein at least one of the selectivity of the reactor to the valuable products (e.g., given X mol of input fluid, you were able to obtain Y mol of the valuable product); efficiency of the reactor (e.g., given X mol of input fluid you used 1,000 kWh); a voltage or current of individual cells; and a voltage or current through an entire reactor. These values or a proxy for these values may need to be calculated in real-time to control the loop. The monitoring process can comprise monitoring an electrical parameter of the oxocarbon electrolysis reactor. The performance of the electrolysis reactor can be derived from the electrical parameter (e.g., an increase in cell voltage can be used to derive a decrease in selectivity). Detecting a decrease in performance can serve as a trigger for a revitalization process to occur. When the device is temporarily stopped, there are variations in the amount of time to wait for the amount of oxidant to supply and variations in pressure further, when the device is operational, there is an increase or decrease in the instantaneous amount of oxidant supplied and it is required to control period between applications.

[0058] In specific embodiments, an excess of oxidant over the required amount will decrease the performance of the valorisation process being conducted by the reactor. As such, a control system can be used to filter decreases in performance that are correlated to oxidant supply from decreases in performance that are uncorrelated to oxidant supply. In response to this determination, the control system can increase oxidant supply for uncorrelated decrease in performance and decrease oxidant supply for correlated decreases in performance.

[0059] In variant embodiments, there are different phases (e.g., gaseous or liquid) for different areas of the electrolyzer such that the oxidant needs to be provided in different ways. For example, electrolyzers can have different phases in different areas: the cathode area can be gaseous (input fluid (e.g., humidified carbon monoxide is delivered as a gas); and the anode area can be aqueous (input fluid (e.g., water) is delivered as a liquid). The opposite is an option as well as dual aqueous and dual gaseous forms.

[0060] FIGS. 8A-8C, are provided with reference to experimental data obtained by practicing specific embodiments of the inventions disclosed herein. Experiments were conducted to show that an oxidant revitalizes the catalyst which is reflected in the data by a performance increase of the electrolysis cells. An experiment is set up for both examples by turning off the voltage, stopping anolyte and carbon monoxide flow, and supplying ambient filtered air through the cathode line while pressurizing at 1.5 bar for 15-30 min, and starting the cell again (i.e., restarting flow to the cells and applying a voltage). Catalyst regeneration is performed by air-flushing the cathode. Two charts are provided (FIGS. 8A and 8B).

[0061] FIG. 8A and FIG. 8B show the cell potential and ethylene selectivity (how much ethylene is being produced vs other products in a %) across time. The experiment in FIG. 8A is conducted with a non-optimized catalyst and the experiment in FIG. 8B is conducted with an optimized catalyst. Both examples show the benefits of catalyst revitalization. The stars show when the electrolyzer was shut down and reactivated. FIG. 8A and FIG. 8B show the benefits of air flushing to recover catalyst activity towards ethylene products in a carbon monoxide electrolyzer. In the illustrated experiments, the performance of the catalyst was revitalized to within 5% of the original performance of the catalyst after each time the oxidant was introduced indicating that continued cycles of revitalizing the catalyst will continue to refresh the catalyst to close to its original condition.

[0062] Further, as shown in FIG. 8C, an experiment is performed to show that the benefits illustrated in FIGS. 8A and 8B are from the introduction of an oxidant, and not some other chemical that revitalizes the catalyst. The experimental setup for FIG. 8C includes carbon monoxide flushing at the cathode, turning off the voltage, stopping anolyte and carbon monoxide flows, pumping carbon monoxide through the cathode line (35 mL/min) while pressurizing 1.5 bar for 15 min, and starting the cell again (i.e., restarting flow to the cells and applying a voltage). Accordingly, FIG. 8C shows that the catalyst is not revitalized as the introduction of the catalyst as marked by the star on the figure does not result in the catalyst being reactivated.

[0063] FIG. 9 illustrates metal contamination at the cathode by SEM/EDX analysis. SEM observations of catalyst morphology before/after revitalizing process. SEM-EDX observations of trace metal contamination on the catalyst surface before/after revitalizing process. In one embodiment of the invention, the catalyst experiences a number of issues that result in the depletion of the performance of the catalyst at the cathode, such as different contaminants or changes to the morphology of the catalyst surface. Further, the embodiments of the present invention solve other issues with the catalyst such as different contaminants or changes to the morphology of the catalyst surface. For example, FIG. 9 illustrates the presence of nickel contaminants on the copper catalyst.

[0064] In FIG. 9, the black and grey dot plot in chart 902 shows selectivity for ethylene production and hydrogen by-product, respectively, and the solid line in chart 902 illustrates the potential across the cell against time. As seen in the chart, selectivity for ethylene begins to dip and the potential starts to drift up after approximately 35 hours of operation. Chart 902 also includes a square drawn towards the right of the plot which shows when the EDX analysis plot 906 and SEM analysis plot 904 were generated. The analysis indicates that the decrease in selectivity is due to Nickel contamination on a copper catalyst.

[0065] FIG. 9 depicts an EDX analysis plot 906 of x-ray energy vs reflective counts per second which is used to show the material content of a sample of the reduction catalyst surface. FIG. 9 illustrates the presence of Ni contaminant at tick 907 just to the left of the large Cu spike at tick 908 which represents the bulk material of the sample.

[0066] FIG. 9 further illustrates a SEM analysis plot 904 of the catalyst surface of the cathode with nickel contamination. The copper and nickel distributions on the surface are shown in the FIG. 9. SEM analysis plot 904 includes a large view of the sample and a darkened square to show the location of nickel contaminant plot 909 and copper material plot 910. Together these plots show that the nickel overlaps with the copper and interferes with the copper surface of the catalyst.

[0067] In specific embodiments of the invention, methods, and systems related to catalysts used in oxocarbon electrolysis reactors in accordance with the summary above are disclosed in detail herein. The methods and systems disclosed in this section are non-limiting embodiments of the invention, are provided for explanatory purposes only, and should not be used to constrict the full scope of the invention. It is to be understood that the disclosed embodiments may or may not overlap with each other. Thus, part of one embodiment, or specific embodiments thereof, may or may not fall within the ambit of another, or specific embodiments thereof, and vice versa. Different embodiments from different aspects may be combined or practiced separately. Many different combinations and sub-combinations of the representative embodiments shown within the broad framework of this invention, that may be apparent to those skilled in the art but not explicitly shown or described, should not be construed as precluded.

[0068] In specific embodiments of the invention, the anode area could comprise an anodic catalyst layer able to oxidize a substance to produce a product and protons. The catalyst can comprise one or more of: molecular species, single-metal-site heterogeneous compounds, metal compounds, carbon-based compounds, polymer electrolytes (also referred to as ionomers), metal-organic frameworks, metal-doped covalent organic framework or any other additives. The molecular species can be selected from metal porphyrins, metal phthalocyanines or metal bipyridine complexes. The metal compound can be under the form of metal nanoparticles, nanowires, nano powder, nanoarrays, nanoflakes, nanocubes, dendrites, films, layers or mesoporous structures. The single-metal-site compounds can comprise a metal-doped carbon-based material or a metal-NC-based compound. Anodic catalyst species used for this purpose could include, but are not limited to, metals and/or ions of: Ir, Co, Cu, Ni, Fe, Pt, Rh, Re, Ru, Pd, Os, Mo and mixture and/or alloys thereof. For example, the anodic catalyst could be Ni such that the electrolyzer assembly included a nickel-based anode. The polymer electrolyte can be selected out of the same materials as the one used for the described membranes. The carbon-based compounds can comprise carbon nanofibers, carbon nanotubes, carbon black, graphite, boron-doped diamond powder, diamond nanopowder, boron nitride or a combination thereof. The additives can be halide-based compounds including F, Br, I, and Cl. The additives can be specifically dedicated to modifying hydrophobicity such as treatment with polytetrafluoroethylene (PTFE), Nafion or another hydrophobic polymeric ionomer additive, or carbon black. The anodic catalyst may be chosen to tune the performance and net product stream of the electrolyzer by choosing catalysts that are more or less capable of anodic alcohol oxidation to the corresponding carboxylic acid, aldehyde, or carbon dioxide.

[0069] The anodic catalyst may be deposited onto a gas diffusion layer or a porous transport layer or any other support that facilitates the diffusion of gas from the interface of the anode to a purified gas stream separated from the cathodic stream. The anode area could also include a gas diffusion layer with one or more separators such as but not limited to membranes, polymeric materials, diaphragm, inorganic material on its borders as described below.

[0070] In specific embodiments of the invention, the cathode area could comprise a catalyst layer able to reduce a substance (e.g., carbon monoxide) to generate value-added hydrocarbons/alcohols/organic acids. The catalyst can comprise one or more: molecular species, single-metal-site heterogeneous compounds, metal compounds, carbon-based compounds, polymer electrolytes (also referred to as ionomers), metal-organic frameworks, or metal-doped covalent organic frameworks or any other additives. The molecular species can be selected from metal porphyrins, metal phthalocyanines or metal bipyridine complexes. The metal compound can be under the form of metal nanoparticles, nanowires, nano powder, nanoarrays, nanoflakes, nanocubes, dendrites, films, layers or mesoporous structures, with precisely chosen particle sizes to control performance. The single-metal-site compounds can comprise a metal-doped carbon-based material or a metal-NC-based compound. The cathode catalyst may be made of a metal or metal ion from metals selected from a group consisting of: Cu, Ag, Au, Zn, Sn, Bi, Ni, Fe, Co, Pd, Ir, Pt, Mn, Re, Ru, La, Tb, Ce, Dy or other metals, lanthanides, and mixture and/or alloys thereof. For example, the cathodic catalyst could comprise Cu such that the electrolyzer assembly included a copper-based cathode. The polymer electrolyte can be selected out of the same materials as the one used for the described membranes. The carbon-based compounds can comprise carbon nanofibers, carbon nanotubes, carbon black, graphite, boron-doped diamond powder, diamond nanopowder, boron nitride or a combination thereof. The additives can be halide-based compounds including F, Br, I, Cl. The additives can be specifically dedicated to modifying hydrophobicity such as treatment with PTFE, Nafion or another hydrophobic polymeric ionomer additive, or carbon black. The cathode may further comprise a catalyst layer on a gas diffusion layer, a porous transport layer, or any other support, which encourages the diffusion of the gas from a stream to the surface of the catalyst, as well as allowing the release of non-reacted/product gases. The cathode area could also include a gas diffusion layer with one or more separators such as, but not limited to, membranes, polymeric materials, diaphragms, and inorganic materials on its borders as described below. The loading of catalyst and additives on the gas diffusion layer can be precisely chosen to favor certain performance characteristics, such as differences in voltage, conductivity, carbon monoxide mass transport rate, product selectivity, and stability.

[0071] In specific embodiments of the invention, the porous support for either the anode area, the cathode area, or both, can be selected from carbon-based porous supports or metal-based porous material or a combination. The carbon-based porous support can be based on carbon fibers, carbon cloth, carbon felt, carbon fabric, carbon paper, molded graphite laminates and the like or a mixture thereof. The carbon-based porous support can be a gas diffusion layer with or without microporous layer. Such carbon-based support can be in particular chosen in the among the following list: Sigracet 39AA, Sigracet 39BC, Sigracet 39BB, Sigracet 39BA, Sigracet 36AA, Sigracet 36BB, Sigracet 35BC, Sigracet 35BA, Sigracet 29BA, Sigracet 28BB, Sigracet 28AA, Sigracet 28BC, Sigracet 25BC, Sigracet 22BB, Sigracet 35BI, Toray papers, Toray THP-H-030, Toray TGP-H-060, Toray TGP-H-090, Toray TGP-H-120, Freudenberg H23C6, Freudenberg H15C13, Freudenberg H15C14, Freudenberg H14C10, Freudenberg H14CX483, Freudenberg H14CX653, Freudenberg H23C2, Freudenberg H23CX653, Freudenberg H24CX483, Freudenberg H23C6, Freudenberg H23C8, Freudenberg H24C5, Freudenberg H23C3, Avcarb MB-30, Avcarb GDS5130, Avcarb GDS2130, Avcarb GDS3250, Avcarb GDS3260, Avcarb GDS2230, Avcarb GDS2240, Avcarb GDS2255, Avcarb GDS2185, AvCar 1071, AvCarb 1698, AvCarbon 1209, AvCarb 1185, AvCarb1186, AvCarb 7497, AvCarb T1819, AvCarb T1820, AvCarb T1824, AvCarbon 1071, AvCarb 1698, AvCarb 1209, AvCarb 1185, AvCarb 1186, AvCarb 1186, AvCarb T1819, AvCarb T1820, AvCarb T1824, AvCarb EP40, AvCarb P75, AvCarb EP55, AvCarbon EP40T, AvCarb P75T, AvCarb EP55T, AvCarb MGL190, AvCarb MGL280, AvCarbMGL370. The metal-based porous support can be selected from titanium, stainless steel, Ni, Cu or any other suitable metal and can be under the form of mesh, frit, foam or plate of any thickness or porosity.

[0072] In specific embodiments of the invention, the electrolyzer can include a separating element to separate specific generated chemicals from others. The separating element can be one or more traps on the cathodic and/or anodic outputs of the electrolyzer which separates liquid outputs from gaseous outputs. It can also be more complex systems known by those skilled in the art for the purpose of efficient product separation. The separating element can be a separating area between the anode area and the cathode area configured to separate the volume of generated chemicals from the electrolyzer. The separating area can be a separating layer. Efficient physical separation of the anode area and cathode area may allow easier separation of the gases released from each section of the reactor. The separator can be an ion-conducting polymeric separator, a non-ion conducting polymeric separators, a non-ionically charged polymer, a non-ionically charged separator, an ionomer solution coated onto the electrodes, a diaphragm, a ceramic-containing material, a non-charged separator scaffold, a mixed ceramic-organic compound separator, or any other separator. Separation may occur through the use of ion-exchange membranes, which favor the diffusion of either anions (in an anion-exchange membrane) or cations (in a cation-exchange membrane), or a bipolar membrane (including a mixture of cation- and anion-exchange membranes) or other types of separators, such as diaphragms, ceramic-containing materials (in particular mixed ceramic/organic compounds), or non-charged separator scaffolds. Anion-exchange membrane can comprise an organic polymer with positively charged functionality, such as, but not limited to, imidazolium, pyridinium or tertiary amines. This allows facile migration of negatively charged hydroxide ions (OH.sup.?) produced during carbon monoxide reduction from the cathode to the anode. The use of this layer also prevents the crossover of other gases from the cathode to the separating layer. Cation-exchange membranes can comprise an organic polymer with negatively charged functionality such as, but not limited to, sulfonate groups. Diaphragms or non-charged separators can be materials derived from insulating materials which may be charged with an ion-conducting electrolyte to facilitate charge transfer between electrodes. Ceramic-containing materials may be a purely ceramic or mixed polymer and ceramic material. Ceramic-polymer mixes can reach higher temperatures than purely organic polymers and may take advantage of ion-exchange functionality in the polymer to pass charge between electrodes. The thickness of the membranes can be chosen precisely to control the transport rates of species such as anions, cations, and neutral species such as alcohols and water during operation.

[0073] In specific embodiments of the invention, the system can include an electrolyte that will facilitate the transportation of ions and provide ions that promote the reactions. In particular, the electrolyte may be a concentrated alkaline solution such as a solution of hydroxide-containing salt such as but not limited to potassium, sodium or cesium hydroxide with concentrations such as (0.01 molarity (M), 0.05 M, 0.1 M, 0.2 M, 0.5 M, 1 M, 2 M, 3 M, 4 M, 5 M, 6 M, 7 M, 8 M, 9 M and 10 M). The use of concentrated alkaline solution brings down the energy requirement of the overall reaction. Alkali metal cations (such as Li, Na, K, Cs, Rb) may be used as counter-cations. This electrolyte may contain oxidation substrates other than water or hydroxide, such as dihydrogen, alcohols, glycerol, other organic materials, and other oxidizable feedstocks.

[0074] While the specification has been described in detail with respect to specific embodiments of the inventions disclosed herein, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Although examples in the disclosure were generally applied to an electrolyzer generating ethylene, the same approaches are applicable to electrolyzers generating any useful chemical or otherwise sequestering or valorizing oxocarbons. Furthermore, while the examples in this disclosure were generally applied to the delivery of carbon monoxide to an electrolyzer, approaches disclosed herein are more broadly applicable to the delivery of any member of the oxocarbon family to an electrolyzer to generate useful chemicals therefrom. These and other modifications and variations to the present invention may be practiced by those skilled in the art, without departing from the scope of the present invention, which is more particularly set forth in the appended claims.