Metal formate formation

Abstract

A system and method are provided for synthesizing metal formate from carbon monoxide supplied by an electrolytic cell having a membrane electrode assembly that incorporates the ability to recover and recycle various chemical components of the production process. For synthesis, the carbon monoxide from the electrolytic cell reacts with a solubilized metal hydroxide in a batch process or a continuous process.

Description

Technical Field

[0001] Incorporation by Reference The PCT Request Form is submitted herewith as part of this application. Each application that claims the benefit or priority identified in the concurrently submitted PCT Request Form is hereby incorporated by reference herein in its entirety for all purposes. Statement of Government Support

[0002] This invention was made with government support under grant number FA864921P1530 awarded by the United States Air Force. The government has certain rights in this invention.

[0003] This disclosure generally relates to metal formate production, and more specifically, to novel and useful systems and methods for advantageously utilizing carbon dioxide electrolyzer products in the reaction with metal hydroxides solubilized in methanol to form metal formates. This production process is configured to efficiently recycle components including intermediates, dryer gas, and methanol and reuse them in metal formate production.

Background Art

[0004] Alkali metal formates have many uses including use as enzyme stabilizers in liquid detergents. The enzyme may be lipase, amylase, protease, etc. Other formates such as alkaline earth metal formates also have many uses. Formates (MHCO2, where M is usually Na, K, or NH4) and formic acid (HCO2H) are commercially available chemicals that can be produced by industrial thermochemical processes. For example, sodium formate and subsequently formic acid can be obtained by the reaction of sodium hydroxide with carbon monoxide followed by acid decomposition with sulfuric acid.

[0005] Formic acid can also be produced as a byproduct of hydrocarbon oxidation and by hydrolysis of methyl formate by carbonylation of methanol. Some synthesis techniques for formates by electroreduction of carbon dioxide have also been described.

[0006] Since carbon dioxide is considered to be the cause of harmful climate change, new and more robust methods for sequestering CO2 and / or converting it efficiently into useful products are still highly desirable in order to protect the environment and at the same time protect valuable and limited resources.

[0007] The description of the background art provided herein is for the purpose of presenting the context of the present disclosure generally. The research of the inventors named at present is not admitted as prior art to the present disclosure, either explicitly or implicitly, within the scope described in this background art section and within the scope of the aspects described which may not be otherwise recognized as prior art at the time of filing.

SUMMARY OF THE INVENTION

[0008] A system and method for synthesizing metal formate from carbon monoxide supplied by an electrolytic cell having a membrane electrode assembly incorporating the ability to recover and recycle various chemical components of the production process are provided. For synthesis, the carbon monoxide from the electrolytic cell reacts with a solubilized metal hydroxide in a batch or continuous process.

[0009] Accordingly, in a first aspect, the present invention includes a system for producing metal formate comprising: (a) a carbon dioxide reduction electrolytic cell having a membrane electrode assembly including one or more ion-conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) at least one formate synthesis reactor configured to receive (i) a carbon monoxide feed produced by the carbon dioxide reduction electrolytic cell and (ii) a methanol feed containing a metal hydroxide; (c) a metal formate separator configured to separate and purify the metal formate produced by the formate synthesis reactor; and (d) a recycle path for recycling the recovered methanol to at least one formate synthesis reactor.

[0010] In some embodiments, the system also comprises a carbon monoxide heater and a carbon monoxide compressor configured to heat and compress carbon monoxide prior to introduction into at least one formate synthesis reactor.

[0011] In some embodiments, the system also comprises a methanol pump configured to transport methanol prior to introduction into at least one formate synthesis reactor.

[0012] In some embodiments, the metal formate separator has a filter connected to a dryer, where the filter is configured to receive the output from at least one formate synthesis reactor, where the output contains metal formate, methanol, and optionally methyl formate, and where the dryer is composed of an inlet for receiving metal formate from the filter and an outlet for removing the dried metal formate; and a gas inlet for supplying a carrier gas and a gas outlet for removing the dryer exhaust gas containing methanol.

[0013] In some embodiments, the output is metal formate, methanol, and methyl formate.

[0014] In some embodiments, the recycle path is a distillation column configured to separate the liquid and / or gas output from the metal formate separator into recovered methanol and recovered methyl formate.

[0015] In some embodiments, the metal formate separator is a filter including a filtrate outlet connected to a distillation column, where the distillation column is configured to produce recovered methyl formate and purified methanol.

[0016] In some embodiments, the system also comprises a path for introducing the recovered methyl formate into at least one formate synthesis reactor.

[0017] In some embodiments, at least one formate synthesis reactor further includes an inlet for receiving the recovered methyl formate.

[0018] In some embodiments, the carrier gas is nitrogen gas.

[0019] In some embodiments, the system comprises a condenser configured to purify the dryer exhaust gas containing methanol to produce a purified carrier gas and a liquid methanol-containing process stream, wherein the purified carrier gas is recycled to the dryer.

[0020] In some embodiments, the system comprises a methanol separator coupled to the condenser, wherein the methanol separator is configured to separate and purify methanol from the liquid methanol-containing process stream to produce purified methanol.

[0021] In some embodiments, the methanol feed includes purified methanol.

[0022] In some embodiments, the methanol separator is a distillation column, a water removal unit, or a combination thereof.

[0023] In some embodiments, the methanol separator is a water removal unit.

[0024] In some embodiments, the water removal unit is a packed bed of desiccant particles.

[0025] In some embodiments, at least one formate synthesis reactor is a first formate synthesis reactor and a second formate synthesis reactor.

[0026] In some embodiments, the first formate synthesis reactor and the second formate synthesis reactor are batch reactors and are configured to be used alternately.

[0027] In some embodiments, at least one formate synthesis reactor is at least two formate synthesis reactors configured in series to operate continuously.

[0028] In some embodiments, the metal formate separator is a centrifuge.

[0029] In some embodiments, at least one formate synthesis reactor is equipped with a stirrer.

[0030] In some embodiments, at least one formate synthesis reactor is equipped with a carbon monoxide inlet nozzle configured to enhance the reactivity of carbon monoxide.

[0031] In some embodiments, the metal hydroxide is sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof.

[0032] In some embodiments, the system includes a mixing tank for solubilizing the metal hydroxide in methanol to produce a methanol feed, and the mixing tank is connected to at least one formate synthesis reactor via a pump.

[0033] In some embodiments, the carbon dioxide reduction electrolyzer and at least one formate synthesis reactor are disposed within a single plant.

[0034] In some embodiments, the dryer and the filter are combined in a single unit.

[0035] In some embodiments, the system also includes an oxalate synthesis reactor configured to convert the metal formate to a metal oxalate, and the system is further configured to transport the metal formate to the oxalate synthesis reactor.

[0036] In some embodiments, the system is further configured to contact the metal oxalate with an acid, thereby producing oxalic acid.

[0037] In some embodiments, the oxalate synthesis reactor is a pressure vessel.

[0038] In some embodiments, the oxalate synthesis reactor is configured to receive a metal carbonate catalyst and perform a reaction to convert the metal formate to a metal oxalate.

[0039] In a second aspect, the present invention includes a method for producing a metal formate, comprising: (a) reducing carbon dioxide to carbon monoxide in a carbon dioxide reduction electrolyzer having a membrane electrode assembly including one or more ion conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) reacting the carbon monoxide produced by the carbon dioxide reduction electrolyzer with a metal hydroxide in methanol in at least one formate synthesis reactor to produce a metal formate; (c) separating and purifying the metal formate produced in (b); and (d) recycling the methanol to at least one formate synthesis reactor.

[0040] In some embodiments, at least one formate synthesis reactor has at least two batch formate synthesis reactors, and the step of reacting the carbon monoxide produced by the carbon dioxide reduction electrolyzer with a metal hydroxide in methanol is performed alternately in the at least two batch formate synthesis reactors.

[0041] In some embodiments, at least one formate synthesis reactor includes at least two batch formate synthesis reactors, and the step of reacting the carbon monoxide produced by the carbon dioxide reduction electrolyzer with a metal hydroxide in methanol is performed continuously in the at least two batch formate synthesis reactors.

[0042] In some embodiments, the step of reacting carbon monoxide with the metal hydroxide is carried out at a reaction temperature of about 60°C to about 200°C and a pressure of about 1 MPa to about 10 MPa.

[0043] In some embodiments, the metal hydroxide has a concentration of about 1 to about 25 weight percent of the metal hydroxide in methanol.

[0044] In some embodiments, the method comprises the step of preheating the carbon monoxide from (a) before reacting in (b).

[0045] In some embodiments, the carbon monoxide is preheated to at least about 100°C.

[0046] In some embodiments, the reaction temperature is about 100°C to about 200°C.

[0047] In some embodiments, the method also comprises the step of forming methyl formate when reacting carbon monoxide with the metal hydroxide in (b).

[0048] In some embodiments, the method also comprises the step of recovering methyl formate by distillation and recycling the methyl formate to at least one formate synthesis reactor.

[0049] In some embodiments, the method comprises the step of drying the metal formate using a carrier gas and generating a dried metal formate and a dryer off-gas stream.

[0050] In some embodiments, the method also comprises the step of condensing a liquid from the dryer off-gas stream to form a condensed liquid.

[0051] In some embodiments, the method also comprises the step of distilling the condensed liquid to obtain recovered methanol.

[0052] In some embodiments, the step of recycling methanol to at least one formate synthesis reactor comprises recycling the recovered methanol to the formate synthesis reactor.

[0053] In some embodiments, (d) includes water removal.

[0054] In some embodiments, the method comprises recovering the released carrier gas; and recycling the released carrier gas to a dryer.

[0055] In some embodiments, the carrier gas is nitrogen gas.

[0056] In some embodiments, the metal hydroxide is sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof.

[0057] In some embodiments, the method also comprises converting the metal formate to a metal oxalate.

[0058] In some embodiments, the method also comprises contacting the metal oxalate with an acid to produce oxalic acid.

[0059] In some embodiments, the method also comprises performing the step of converting the metal formate to a metal oxalate at a pressure above atmospheric pressure.

[0060] In some embodiments, the step of converting the metal formate to a metal oxalate is by contacting the metal formate with a metal carbonate catalyst.

[0061] In a third aspect, the present invention provides a process for producing metal formate, comprising: (a) reducing carbon dioxide to carbon monoxide in a carbon dioxide reduction electrolyzer comprising a membrane electrode assembly having one or more ion conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) mixing a metal hydroxide in methanol in a mixing tank to obtain a metal hydroxide solubilized in methanol; (c) feeding the carbon monoxide produced in (a) to at least one formate synthesis reactor, wherein the carbon monoxide is fed to the formate synthesis reactor at a pressure of about 1 MPa to about 10 MPa together with the metal hydroxide solubilized in methanol; (d) reacting the carbon monoxide with the metal hydroxide solubilized in methanol at a reaction temperature of about 60 °C to about 200 °C to produce a metal formate; (e) outputting a metal formate-containing stream containing metal formate, methanol and optionally methyl formate from at least one formate synthesis reactor; (f) filtering the metal formate-containing stream produced in (e) to obtain a solid metal formate and a filtrate containing methanol and optionally methyl formate; (g) drying the solid metal formate produced in (f) in a dryer with a carrier gas to produce a dried metal formate and an exhaust gas stream containing methanol and the carrier gas; and (h) distilling the filtrate to produce methanol for recycling to the mixing tank and optionally methyl formate for feeding to the formate synthesis reactor.

[0062] In one embodiment, the process further comprises purifying the exhaust gas stream of (g) to obtain a recovered carrier gas and recycling the recovered carrier gas to the dryer.

[0063] In one embodiment, the solubilized metal hydroxide is about 1 to about 25 weight percent of the metal hydroxide in methanol.

[0064] In one embodiment, the process further comprises preheating the carbon monoxide produced in (a) before (c).

[0065] In some embodiments, the carbon monoxide produced in (a) is preheated to at least 100 °C.

[0066] In some embodiments, the reaction temperature in (d) is from about 100 °C to about 200 °C.

[0067] In some embodiments, the carrier gas is nitrogen gas.

[0068] In some embodiments, the metal hydroxide is sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof.

[0069] In a fourth aspect, the present disclosure includes a method for producing a metal formate. In some embodiments, the method comprises: (a) reducing carbon dioxide to carbon monoxide in a carbon dioxide reduction electrolyzer comprising one or more ion-conductive polymer layers and a membrane electrode assembly having a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) reacting the carbon monoxide produced by the carbon dioxide reduction electrolyzer with methanol in at least one methyl formate synthesis reactor to produce methyl formate, and then separating and purifying the methyl formate; (c) hydrolyzing methyl formate to formic acid using water in at least one methyl formate hydrolysis reactor, and then separating and purifying the formic acid; (d) reacting the formic acid with a metal carbonate to produce a metal formate; and (e) recycling the methanol from step (b) and the water from step (c) to at least one methyl formate synthesis reactor, and recycling the water from step (c) to at least one methyl formate hydrolysis reactor, wherein the metal formate is calcium formate or potassium formate, and the metal carbonate is calcium carbonate or potassium carbonate.

[0070] These and other features of the present disclosure will be described in detail below with reference to the associated drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0076] Definitions As used herein, the term “about” is understood to account for a slight increase and / or decrease beyond the recited value, such changes not materially affecting the desired function of the parameter beyond the recited value. In some cases, “about” encompasses + / −10% of the recited value. As used herein, this term modifies any recited value, range of values, or endpoints of one or more ranges.

[0077] As used herein, the terms "top", "bottom", "upper", "lower", "above", and "below" are used to provide a relative relationship between structures. The use of these terms does not indicate or require that a particular structure must be located in a particular place within the device.

[0078] As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C) using an inclusive disjunction, and should not be construed to mean "at least one of A, at least one of B, at least one of C".

[0079] As used herein, the phrase "recycle path" means any combination of condensation, purification, and separation units necessary to prepare reaction intermediates, by-products, carrier gases, or solvents for reuse, and includes means (e.g., delivery lines, compressors, pumps, or the like) for returning the recovered intermediates, by-products, solvents, and / or carrier gases to the reactor or other appropriate re-entry point in the production process.

[0080] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail in order not to unnecessarily obscure the disclosed embodiments. The disclosed embodiments are described in conjunction with specific embodiments, but it is understood that the disclosed embodiments are not intended to be limiting. Summary

[0081] Aspects of the present disclosure relate to systems and methods for integrating a carbon dioxide reduction electrolyzer with one or more metal formate synthesis reactors. As described elsewhere herein, the carbon dioxide reduction electrolyzer can be configured to efficiently reduce carbon dioxide to carbon monoxide. In certain embodiments, the carbon monoxide produced by such an electrolyzer reacts with a metal hydroxide to produce a metal formate. This is carried out in one or more of the above-described metal formate synthesis reactors.

[0082] In some implementations, carbon monoxide from the carbon dioxide electrolyzer and a metal hydroxide dissolved in methanol are provided to one or more metal formate synthesis reactors. In these one or more reactors, the metal hydroxide and the carbon oxide react to form a metal formate.

[0083] In some embodiments, the system is designed or configured to conserve methanol by recovering methanol from the reaction stream, purifying it, and recycling it to dissolve fresh metal hydroxide prior to introduction into one or more metal formate synthesis reactors.

[0084] In some embodiments, the system is designed or configured to dry the solid metal formate produced by one or more metal formate synthesis reactors using a drying gas. The system may be designed or configured to recycle the drying gas. In certain embodiments, the metal formate synthesis reaction in one or more metal formate synthesis reactors produces methyl formate as an intermediate product. In such embodiments, the output stream of one or more metal formate synthesis reactors contains some methyl formate. In such cases, the system may be designed or configured to separate the recovered methanol and methyl formate and then reuse the methanol in a recycle stream. In some implementations, the methyl formate separated from the methanol is fed back directly to one or more metal formate synthesis reactors, while the purified methanol is first mixed with fresh metal hydroxide and then reintroduced into one or more metal formate synthesis reactors together with the dissolved metal hydroxide.

[0085] Regarding the reaction of carbon monoxide with metal hydroxide in methanol, the solubility of carbon monoxide in methanol may limit the reaction rate. The reaction rate of carbon monoxide with metal hydroxide may exhibit a second-order reaction rate depending on the concentration of carbon monoxide. Thus, in some implementations, the integrated system and method feature increasing the concentration of carbon monoxide in the methanol within one or more metal formate synthesis reactors.

[0086] One approach for increasing the concentration of carbon monoxide is to increase the pressure of carbon monoxide before introduction into one or more metal formate synthesis reactors above its pressure in the carbon dioxide electrolyzer.

[0087] Another approach employs the step of mixing carbon monoxide gas with a methanol-containing reaction mixture so as to increase the interfacial surface area between the carbon monoxide gas and the methanol liquid. For this purpose, various mechanisms can be employed. In some embodiments, one or more metal formate synthesis reactors operate with a certain agitation to move the carbon monoxide bubbles within the reaction mixture. Another approach employs a carbon monoxide introduction nozzle configured to introduce carbon monoxide into the reaction mixture so as to maximize the surface area of the interface between the carbon monoxide and the liquid phase. The reactor and nozzle designs that facilitate this high surface area contact are described elsewhere in this specification.

[0088] The formate synthesis reaction can be represented by the following chemical formula: CO + MOH → HCOOM

[0089] In certain embodiments, the reaction is carried out at a high temperature, such as about 100 to 200 °C. Since the reaction is exothermic, the system can be configured so as not to require preheating of the methanol. In some embodiments, the metal formate synthesis reaction employs a relatively small amount of methanol. In some embodiments, C1-C4 alcohols such as ethanol, propanol, isopropyl alcohol, or butanol can be utilized as a solvent. In certain embodiments, the concentration of the metal hydroxide in methanol is at least about 13 wt%. Note that the solubility limit of sodium hydroxide in methanol is about 23.1 wt%.

[0090] In some implementations, the carbon monoxide is preheated before introduction into one or more metal formate synthesis reactors, while the methanol is not preheated before introduction into the reactors.

[0091] Considering that the reaction rate of the metal formate synthesis reaction is relatively slow, the system can employ a batch reactor instead of a continuous reactor. The batch reactor presents throughput challenges in that the non-reactor components of the system may need to be idled while the batch reactor is being replenished and the metal formate synthesis reaction is restarted. To address such challenges, in some embodiments, the system employs two or more batch synthesis reactors. When employing two or more such reactors, the individual reactors can be operated non-simultaneously, such that one reactor reacts while the other is being replenished. In this way, metal formate can be continuously produced and continuously supplied to the downstream components of the system. In some embodiments, the system employs two or more continuous reactors arranged in series.

[0092] In a particular implementation of the system, methanol recycling is employed. Among previous designs, there were some that permitted methanol to be released into the atmosphere during one or more process steps, such as the drying stage of the metal formate reaction product. Generally, the air or nitrogen used in the drying process was released into the atmosphere. Methanol is a volatile organic compound permitted in flue gas at a maximum concentration of 200 ppm in accordance with US OSHA regulations. It is possible to combust volatile organic compounds such as methanol in flue gas, but the required temperature is typically about 400 °C. Thus, the combustion process is energy-intensive and fossil fuels are regularly used to achieve the required temperature.

[0093] To reduce the environmental impact of the formate synthesis reaction, the system may be configured as a closed system in which nitrogen or other drying gas is continuously recycled and methanol in the drying gas stream is condensed without being released or combusted. The methanol recovered in this way may be recycled to the formate synthesis reactor.

[0094] In certain embodiments, since methanol is highly flammable, nitrogen is employed as the drying gas. In some limitations, the system employs a rotary dryer to evaporate methanol from solid metal formate. Methanol remaining in the nitrogen stream is condensed in a condenser, and the newly dried nitrogen is recycled back to the inlet of the rotary dryer.

[0095] In some reactors, methyl formate is an intermediate in the reaction of carbon monoxide and metal hydroxide in methanol. In some embodiments, the liquid outlet stream of the metal formate synthesis reaction may contain about 5-10 wt% methyl formate.

[0096] In various embodiments, the liquid component of the reactor outlet stream is processed to separate methanol from methyl formate. In some implementations, the separation is achieved by distillation. In some embodiments, the metal formate stream is fed back directly to the metal formate synthesis reactor, where it may react with the metal hydroxide to produce metal formate. In some implementations, the purified methanol from which most or all of the methyl formate has been removed is fed back to the mixer, where it solubilizes fresh metal hydroxide, and then the hydroxide is introduced into one or more metal formate synthesis reactors.

[0097] Systems and / or methods for carbon dioxide reactor control can be configured to control aspects of reactor production, such as aspects related to the amount, concentration, and / or ratio of reactor products. The electrochemical carbon dioxide reduction cell can be integrated with any of a variety of other chemical processing systems, such as chemical reactors, chemical separation units, purification units, and the like, along with an associated sensing and / or control system. The integrated system can employ an electrochemical carbon dioxide reduction cell and another chemical processing system arranged upstream, downstream, or in parallel with this electrochemical carbon dioxide reduction cell.

[0098] Examples of carbon oxide reactants typically include, although not necessarily in gaseous form, carbon dioxide and carbon monoxide. Other examples of carbon oxide reactants include carbonate ions and compounds, and bicarbonate ions and compounds.

[0099] Typical systems and methods for carbon dioxide reactor control have focused on maximizing aspects related to the production of CO and / or other carbon-containing products (CCPs) (e.g., carbon-containing species: CCSs), such as the ratio of carbon monoxide (CO) to other reactor products (e.g., the CO:H2 ratio), the CO concentration, and / or the maximization of the total CO output or output rate.

[0100] However, simply maximizing aspect values may not be desirable, and it may be beneficial to not just maximize but rather arbitrarily control such aspects (e.g., dynamic or selective aspect control to meet values within a series of target aspect values). For example, it may be desirable to selectively control the CO:H2 ratio of the reactor products (e.g., enable any control within a spectrum ranging from the maximum possible CO:H2 ratio for a given system and / or process down to approximately 1:3 or lower CO:H2). Such control can enable more effective use of the reactor output (e.g., where the reactor output is fed directly into subsequent inputs).

[0101] Figure 1 is a schematic flowchart of a particular embodiment of the present invention, where operation 100 is shown for using the product gas from carbon dioxide reactor 120 of the present disclosure, such as carbon monoxide, in one or more downstream processes including metal formate synthesis 140. Optionally, the metal formate produced can be further used as a reactant in an oxalate synthesis process 160 to form oxalic acid. In some embodiments, operation 100 includes a step of recycling up to three chemical components during metal formate production. The system is configured to enable recycling of methanol 142, carrier gas such as nitrogen 146, and optionally methyl formate 144 (if present). Such a configuration results in a more efficient and environmentally friendly production process. Electrolyzer

[0102] In some embodiments, process 100 begins with carbon dioxide electrolysis 120. In some embodiments, electrolysis system 120 can comprise a carbon dioxide reactor, such as a reactor that generates a carbon-containing product (e.g., CO, alkane, alcohol, etc.) and / or hydrogen from an input containing carbon dioxide (e.g., an input stream such as a fluid stream). The reactor may be configured to receive a gaseous carbon dioxide input and / or perform a reaction using gaseous carbon dioxide (e.g., is a gas-phase reactor), but additionally or alternatively can receive a liquid-phase carbon dioxide input, a supercritical fluid-phase carbon dioxide input, a solid-phase carbon dioxide input, and / or any other suitable carbon dioxide input.

[0103] The electrolytic cell may include one or more electrodes (e.g., anode, cathode), a catalyst (e.g., inside and / or in the vicinity of the cathode and / or anode), a gas diffusion layer (e.g., in the vicinity of the cathode and / or anode), and / or a flow field (e.g., a flow field defined inside and / or in the vicinity of the electrode and / or gas diffusion layer, one or more channels defined opposite the cathode across the gas diffusion layer, etc.). In some embodiments, the electrolytic cell includes a membrane stack or a membrane electrode assembly (MEA) having one or more polymer electrolyte membranes (PEMs) that provide ion transfer between the anode and cathode of the electrolytic cell. In certain embodiments, the electrolytic cell includes a membrane stack that includes a cathode layer containing a reduction catalyst and an ion-conductive polymer; a PEM membrane (e.g., bipolar membrane, unipolar membrane, etc.; a membrane containing one or more anion conductors such as anion exchange membranes (AEMs), proton and / or cation conductors such as proton exchange membranes, and / or any other suitable ion-conductive polymer; a membrane containing one or more buffer layers; etc.); and an anode layer containing an oxidation catalyst and an ion-conductive polymer. The ion-conductive polymers of each layer may be the same or different ion-conductive polymers.

[0104] In some embodiments, one or more of the catalysts (e.g., reduction catalysts, oxidation catalysts) may include catalyst particles such as nanoparticles (e.g., defining a porous network of the particles). One or more of the catalysts can additionally or alternatively include one or more polymer electrolytes, and optionally, the polymer electrolyte is mixed with the catalyst nanoparticles (e.g., disposed within the porous network such as loaded into the open regions defined by the porous network). The catalyst nanoparticles can define one or more characteristic sizes (e.g., average size, median size, minimum size, maximum size, size at a particular percentile of the particle size distribution, etc.), and / or the porous network can define porosity (e.g., the proportion of empty space within the network), density, circuitousness (e.g., characteristic path length per layer thickness, area, and / or volume, e.g., a path through empty space or a path along interconnected particles, etc.), and / or any other suitable porous network metric.

[0105] In some configurations, the bipolar MEA has the following laminate arrangement: cathode layer / cathode buffer layer (anion-conductive layer) / cation-conductive layer (which may be a PEM) / anode layer. In some implementations, the bipolar MEA has a cathode layer containing an anion-conductive polymer and / or an anode layer containing a cation-conductive layer. In some implementations, the bipolar MEA has an anode buffer layer that may contain a cation-conductive material between the cation-conductive layer and the anode layer.

[0106] In some configurations, the bipolar MEA has the following laminate arrangement: cathode layer / cation-conductive layer (which may be a PEM) / anion-conductive layer / anode layer. In some applications, the bipolar MEA having this arrangement is configured in a system for reducing carbonate and / or bicarbonate raw materials such as an aqueous solution of carbonate and / or bicarbonate.

[0107] In some configurations, the MEA has the following laminate arrangement: cathode layer / anion conductive layer / anode layer. In some implementations, this MEA does not have a cation conductive layer between the cathode layer and the anode layer. In some applications, an MEA containing only an anion conductive material between the cathode and the anode is configured in a system for reducing a carbon monoxide feedstock.

[0108] In one example (``electrolyzer configuration A''), the system includes a carbon fiber paper gas diffusion layer (e.g., Sigracet 39BC); a catalyst layer (e.g., Fumasep FAA-3) including approximately 20 wt% of gold particles of approximately 4 nm on Vulcan carbon and an anion conductive polymer; a bipolar PEM; and a flow field, e.g., a single, double, triple, or quadruple serpentine flow field or an interdigitated flow field. In a specific example, the electrode defines an area of approximately 25 cm 2 but additionally or alternatively, may define any other suitable area.

[0109] In some embodiments, the electrolyzer includes one or more elements as described in U.S. Patent Application No. 15 / 586,182, filed May 3, 2017 (U.S. Patent No. 10,822,709) and entitled ``Reactor with Advanced Architecture for Electrochemical Reactions of CO2, CO, and Other Compounds'', which is incorporated herein by reference in its entirety. However, additionally or alternatively, the electrolyzer may include any other suitable elements in any suitable arrangement.

[0110] Additional information regarding optional embodiments and / or elements of the system and / or method is provided below in U.S. Patent Application Publication No. 2017 / 0321334, filed May 3, 2017 (U.S. Patent No. 10,822,709) and U.S. Provisional Patent Application No. 62 / 939,960, filed November 25, 2019 (U.S. Patent Publication No. 2021-0207275), which are incorporated herein by reference in their entirety.

[0111] The carbon oxide reduction electrolytic cell may include more than one cell or MEA. The plurality of cells or MEAs may be arranged in a stack and electrically connected to each other in series and / or in parallel. Unless otherwise specified, all references herein to carbon oxide reduction electrolytic cells, carbon oxide electrolytic cells, and the like, embody both single cell electrolytic cells and multiple cell stacks of electrolytic cells.

[0112] The carbon oxide reduction electrolytic cell can obtain carbon oxides from various sources. As mentioned, examples of carbon oxide reactants include carbon dioxide, carbon monoxide, carbonates, and / or bicarbonates. In certain embodiments, the carbonate or bicarbonate is provided in the form of an aqueous solution (e.g., an aqueous solution of potassium bicarbonate) that can be delivered to the cathode of the reduction cell. Carbonates and bicarbonates can be obtained from various sources (e.g., minerals) and / or by various reactions (e.g., reacting carbon dioxide with a hydroxide).

[0113] Optionally, the system may comprise an upstream source of carbon dioxide input connected to the input of the carbon dioxide electrolyzer of the present disclosure, which includes a biogas generation system; an ethanol fermentation system such as a corn ethanol generation system, a beer generation system, a wine generation system; a natural gas processing system; a cement generation system; a blast furnace system, e.g., a steel blast furnace system capable of generating blast furnace gas; a coke oven gas generation system; a power generation system such as an oil power plant system, a natural gas power plant system, a coal power plant system; an oil refining system; an ethylene generation system; an ammonia generation system; a hydrogen generation system such as a water gas shift system; a natural gas processing plant (e.g., Benfield treatment); an ethylene oxide generation system; an aluminum smelting system; a liquefied natural gas (LNG) generation system; a solid feedstock gasifier (e.g., municipal solid waste, biomass, or coal feedstock); a reformer (e.g., steam methane reformer, autothermal reformer); a system that performs the Bouduard reaction; direct air capture (DAC) of the carbon dioxide process; and / or any other system capable of generating carbon dioxide, including one or more of them. The upstream source of carbon dioxide may be directly connected to the input of the carbon dioxide reactor of the present disclosure (e.g., functioning as an input such as being connected to the reduction catalyst via a cathode flow field and / or a gas diffusion layer, etc.), or alternatively, the upstream source may be connected to a purification system; a gas compression system; or both a purification system and a gas compression system in any order, which are then connected to the input of the carbon dioxide system of the present disclosure. A plurality of purification and / or gas compression systems (e.g., scrubbers, etc.) may be employed.

[0114] Carbon dioxide, carbon monoxide, or carbonate provided as an input to the carbon oxide reduction electrolytic cell can have a range of concentrations depending on the reactor structure and operating conditions. In certain embodiments, the carbon dioxide provided to the carbon dioxide reduction electrolytic cell has a concentration of at least about 20 mole percent, or at least about 40 mole percent, or at least about 75 mole percent, or at least about 90 mole percent. In certain embodiments, the carbon dioxide provided to the carbon dioxide reduction electrolytic cell has a concentration of about 40 - 60 mole percent.

[0115] The upstream source of the electrolytic carbon oxide reduction electrolytic cell can be derived in various forms from any of a variety of sources, such as purified tap water, purified seawater, by - products of direct air capture of water (optionally including capture of carbon dioxide), combustion processes that can also produce a carbon dioxide feedstock, fuel cell by - products, and the like.

[0116] The system can comprise an input to a downstream system that is connected to the output of the carbon dioxide electrolytic cell of the present disclosure and that can convert the chemical output from the carbon dioxide electrolytic cell of the present disclosure. The carbon dioxide electrolytic cell output of the present disclosure can be directly connected (e.g., via the cathode flow field and / or gas diffusion layer) to the downstream system, and / or the carbon dioxide electrolytic cell output can be connected in either order to a purification system; a gas compression system; or both a purification system and a gas compression system, which are then optionally connected to the input of the downstream system. Multiple purification systems and / or gas compression systems may be employed.

[0117] The downstream system can generate carbon dioxide output in addition to other product outputs. The system may further include a connection between the carbon dioxide-containing output of the downstream system and the input of the carbon dioxide electrolyzer. The carbon dioxide-containing output of the downstream system may be directly connected to the input of the carbon dioxide reactor of the present invention, or alternatively, the downstream carbon dioxide-containing output may be connected to a purification system; a gas compression system; or both a purification system and a gas compression system in any order, which is then connected to the input of the carbon dioxide electrolyzer of the present disclosure. A plurality of purification systems and / or gas compression systems may be employed.

[0118] The carbon dioxide electrolyzer of the present invention can produce a series of products (e.g., methane, ethylene, carbon monoxide (CO), hydrogen molecules (H2), ethanol, formate, formic acid, acetate, acetic acid, propanol, butanol, ethane, methanol) that can be used in downstream systems and processes. Different carbon dioxide electrolyzers (e.g., including different layer stacks, catalysts and / or catalyst layers, PEMs, flow fields, gas diffusion layers, cell compression configurations, and / or any other suitable aspects, etc.) can be used to achieve different reduction products (e.g., product compositions such as HCR); however, different reduction products can additionally or alternatively be achieved by adjusting operating parameters and / or in other ways. Many possible downstream systems and processes emit CO2 (examples include the bioreutilization of methane, the bioreutilization of formic acid or formate, the bioreutilization of acetic acid or acetate, the Fischer-Tropsch process, and methanol synthesis). In many of these cases, a carbon dioxide recycle system appropriately sized for a particular application can be used to return CO2 from the downstream system output to the input of the carbon dioxide electrolyzer of the present disclosure to increase the carbon efficiency of the overall process.

[0119] The system may further include a source of electrical energy connected to the carbon dioxide electrolyzer, and the source of electrical energy may include one or more of a solar power generation system; a wind power generation system; a geothermal power generation system; a fossil fuel power generation system; or any other system capable of generating electrical energy.

[0120] The system may be employed to store electrical energy in the form of chemical energy. For example, a power producer can generate surplus power during off-peak usage periods. A system containing a carbon oxide reduction electrolyzer can respond quickly to the need to consume surplus power. They do not need to warm up for operation, and they can cycle between a powered-on state and a powered-off state without degradation of the carbon dioxide reactor. The ability to respond quickly to power utilization needs enables the system to work well with intermittent power sources such as solar power generation systems and wind power generation systems.

[0121] One embodiment of the system may include an upstream bioreactor, a carbon dioxide electrolyzer, and an intermittent source of electrical energy. When power is available from the sun, or wind, or low off-peak demand, or other sources, a power availability detector may be used to start the carbon dioxide electrolyzer. Also, the system may boost the output of the upstream bioreactor, for example, by increasing the temperature of the upstream bioreactor and increasing the flow of nutrients to the upstream bioreactor. For other upstream carbon dioxide sources, other means may be used as needed to increase the flow of carbon dioxide to the input of the carbon dioxide electrolyzer of the present disclosure.

[0122] Any system disclosed herein may comprise components (e.g., sensors, systems, etc.) for measuring conditions, outputs, and inputs in a system connected to a carbon dioxide electrolyzer. Such components may include chemical property measurement systems such as gas chromatographs, mass spectrometers, infrared spectrometers, visible light spectrometers, and / or ultraviolet spectrometers; temperature detectors; flow rate measurement sensors; power availability detectors; and / or any other optional monitoring systems. The monitoring system can monitor parameters of input and / or output streams, parameters of components of input and / or output streams (e.g., impurity concentration, carbon dioxide concentration, product concentration, etc.), and / or any other suitable parameters of the streams.

[0123] Any system disclosed herein may comprise components for responding to conditions measured in a system connected to a carbon dioxide reactor. Such components may include systems for adjusting flow rate, temperature, power consumption, or other system parameters. The system may include one or more carbon dioxide electrolyzers. However, additionally or alternatively, the system may include any other suitable elements in any suitable arrangement. In various embodiments, one or more monitoring or sensing components are used in conjunction with a control system comprising a controller (e.g., including a processor and memory) having appropriately programmed or constructed logic to determine that one or more operating conditions should be modified and to cause such operating conditions to be modified. Feedforward and / or feedback control systems may be employed. Method of using an electrolyzer

[0124] The method can be carried out using any of the above components including an electrochemical carbon oxide reduction electrolyzer, but additionally or alternatively, it can also be carried out using any other suitable system. The method optionally comprises operating the electrolyzer under controlled process conditions (e.g., described in more detail below) to produce a desired output (e.g., CO, H2, etc.) at a desired ratio (e.g., molecular hydrogen to CCP ratio (HCR) and / or CCP to molecular hydrogen ratio), and / or changing the process conditions to change the output and / or output ratio.

[0125] The step of operating the electrolyzer may include providing one or more inputs (e.g., gas, liquid, solid, etc.) such as carbon dioxide, carbon monoxide, a carbon oxide source (e.g., waste gas), and / or water, subjecting all or part of the input to a reaction (e.g., by applying a voltage to the electrodes of the device), thereby generating a product, and / or removing the product from the electrolyzer (e.g., as an output gas stream). Such a reaction may include, for example, reducing carbon dioxide and / or water to generate products such as CO (and / or other CCPs, e.g., formic acid, methanol, glyoxal, methane, acetic acid, glycolaldehyde, ethylene glycol, acetaldehyde, ethanol, ethylene, hydroxyacetone, acetone, allyl alcohol, propionaldehyde, n-propanol, etc.), and / or H2. However, the step of operating the electrolyzer may additionally or alternatively include causing any other suitable reaction, and / or may additionally or alternatively include any other suitable element carried out in any suitable manner.

[0126] The method may comprise the step of controlling the system to achieve a desired set of process conditions (e.g., aspects), such as process conditions known to result in a desired output metric value (e.g., a desired CCP:H2 ratio such as a CO:H2 ratio). The method may additionally or alternatively comprise the step of changing the process conditions (e.g., to reduce or eliminate the difference) based on the difference between the actual output and the desired output. For example, the method may comprise the steps of imposing an initial set of process conditions; monitoring one or more output metrics (e.g., CCP:H2 ratio); determining that the output metric is different from the target output metric (e.g., greater than or less than the target); changing one or more process conditions to reduce the difference in the output metric (e.g., reducing or increasing the process condition value such as a condition where the output metric tends to increase or decrease with an increase in the process condition value); optionally, continuing to monitor the output metric and / or change the process conditions (e.g., implementing closed-loop control of the process conditions based on the output metric).

[0127] Optionally, the method may comprise the step of determining a target output metric, which functions to determine which parameter or aspect (e.g., an important parameter for a given application or downstream system) should be targeted. For a given process, one or more target output metrics may be selected. The target output metric can be an output metric associated with (e.g., pre-determined, indicated, etc.) the application (e.g., the application described above such as Fischer-Tropsch); a randomly selected output metric; an output metric determined empirically (e.g., through iterative testing and monitoring of the performance of a downstream application); an optimized output metric (e.g., based on operating parameters of a downstream application, reactor operating parameters, etc.); an output metric specified by a user; and / or an output metric determined otherwise.

[0128] Optionally, the method may comprise the step of determining a target value for the target output metric, which functions to identify the value to target (from a series of values). In some variations, the target value may be a maximum or minimum value (e.g., an actually achievable maximum or minimum value, a theoretical maximum or minimum value, etc.). However, additionally or alternatively, the target value may not be an extreme value (e.g., it may be an intermediate value or a range of values between the maximum and minimum values). The target value can be a value associated with the application (e.g., pre-determined, pre-associated); a randomly selected value; an empirically determined value (e.g., through iterative target value selection, monitoring the performance of downstream applications, and adjusting the target value based on the performance of the application); an optimized value (e.g., based on operating parameters of downstream applications, reactor operating parameters, etc.); or a differently determined value. However, the target value can be any other appropriate value and can be determined in any appropriate manner.

[0129] Under some conditions, the method may achieve a carbon dioxide conversion (e.g., CO partial yield) greater than 95% (e.g., up to 100%), e.g., a system operating under such conditions may achieve at least a threshold conversion metric. However, additionally or alternatively, the method may achieve a carbon dioxide conversion greater than 50%, 60%, 70%, 80%, 90%; within the range of 10% - 100%, e.g., 10% - 40%, 30% - 50%, 40% - 60%, 50% - 70%, 60% - 75%, 70% - 85%, 80% - 95%, 90% - 95%, 92% - 98%, and / or 95% - 100%; and / or any other appropriate carbon dioxide conversion.

[0130] The method optionally comprises the step of providing the electrolytic cell product (or a subset thereof) to a consumer downstream of the product (e.g., as described above with respect to the application of the electrolytic cell output; or as described below in the Examples section; etc.). Optionally, the method may comprise the step of modifying the electrolytic cell product after it has been produced (e.g., before supplying the modified product to a downstream consumer; etc.). Optionally, the step of modifying the electrolytic cell product may comprise the step of purifying the product (e.g., SO x and / or NO xA step of removing impurities such as may be provided from the reactor output stream. Additionally or alternatively, the step of modifying the electrolyzer product may include, for example, a step of mixing additional gas (and / or other substances) into the electrolyzer output stream (and / or input stream) to achieve a desired output metric. In one variant, if the CO:H2 ratio of the electrolyzer output is different from the desired value, this ratio can be adjusted by mixing the electrolyzer output with other gases (e.g., substantially pure CO and / or H2; the output of a previously generated and stored electrolyzer, the output of a second electrolyzer, the output of another system, and / or another mixture of CO and H2 such as waste gas, etc.). For example, the CO:H2 ratio of the output stream (and / or the gas in any other part of the electrolyzer) can be monitored (e.g., continuously during electrolyzer generation), and a deviation from the desired value can be compensated for by mixing with other gases (e.g., adding CO and / or a CO-rich mixture to increase the ratio, and / or adding H2 and / or an H2-rich mixture to decrease the ratio). This example may also include a step of changing process conditions to modify the electrolyzer output (e.g., as described above for closed-loop control). In a second variant where an external gas supply (e.g., the output and / or waste gas of one or more other systems such as a steelworks) is supplied to a downstream consumer (e.g., a gas fermenter), the electrolyzer product is used to change the CCP:H2 ratio (e.g., the CO:H2 ratio) of the external gas supply (e.g., if the CCP:H2 ratio of the external gas supply is different from the desired value, mixing the electrolyzer product to achieve the desired value). For example, based on a deviation from the desired value of the external gas supply, the process conditions can be controlled to change the CO:H2 ratio of the electrolyzer product (e.g., increasing the ratio in response to an external gas supply low in CO, decreasing the ratio in response to an external gas supply rich in CO), and / or the amount of electrolyzer product mixed into the external gas supply can be controlled (e.g., to achieve the desired value). However, additionally or alternatively, the electrolyzer output stream may be modified in any other suitable manner or may be used without modification.

[0131] In some examples, the method comprises determining one or more metrics (e.g., operating metrics) associated with one or more upstream and / or downstream elements of the system (e.g., downstream reactor, upstream input, etc.). Such operating metrics may include, for example, electrolyzer conditions such as temperature, pressure, etc.; output metrics of the downstream reactor and / or upstream source such as throughput, composition, purity, etc.; metrics associated with other inputs for the downstream reactor such as input quantity, composition, purity, etc.; reactor efficiency metrics; and / or any other suitable metrics. In such examples, the method may comprise changing the operation of the carbon dioxide electrolyzer based on the metrics, for example, by changing the HCR of the carbon dioxide reactor output (e.g., to improve and / or maintain the operation of the downstream reactor; to adapt to changes in the upstream source, etc., to improve and / or maintain the operation of the carbon dioxide electrolyzer; to improve and / or maintain target output metrics such as HCR or reduced product concentration assuming a changing carbon dioxide source; etc.). However, additionally or alternatively, the method may include determining any other suitable metrics and / or acting in any other suitable manner (e.g., based on the metrics). Electrolyzer process conditions

[0132] Process conditions can include, for example, input carbon dioxide flow rate and / or pressure, input gas hydration, current density, voltage (e.g., maintained between about 1.5 V and 3 V, additionally or alternatively, operated at less than about 1.5 V, between about 2 V and 2.5 V, between about 2 V and 4 V, above about 4 V, and / or at any other suitable voltage), and / or temperature. Additionally or alternatively, process conditions can include system configurations such as the sides of the gas diffusion layer, the catalyst, the flow field, and / or the PEM. However, any other suitable process conditions can be controlled or targeted. Process conditions can also not be controlled (e.g., as directed by an upstream system), or can be controlled to meet a target value (e.g., the target value can be determined based on an application receiving the reactor output, an instantaneous or expected reactor operating parameter, or otherwise), or can be determined otherwise.

[0133] The process conditions may include a pressure greater than atmospheric pressure (e.g., within a threshold pressure range and / or greater than a threshold pressure range, e.g., about 1 - 5 atm, about 5 - 10 atm, about 10 - 20 atm, about 20 - 50 atm, about 50 - 100 atm, about 100 - 300 atm, about 300 - 1000 atm, about 1 - 10 atm, about 5 - 50 atm, about 10 - 100 atm, about 20 - 500 atm, and / or greater than 1000 atm, about 14 - 50 psi, about 50 - 150 psi, about 100 - 300 psi, about 200 - 500 psi, about 500 - 1000 psi, about 750 - 1500 psi, about 1000 - 3000 psi, about 3000 - 10,000 psi, about 10,000 - 20,000 psi, and / or greater than about 20,000 psi, etc.), and / or a pressure greater than a pressure typically achievable in an electrolytic cell other than a gas-phase electrolytic cell (e.g., input gas pressure, electrolytic cell pressure, etc.). Additionally or alternatively, the process conditions may include a pressure substantially equal to 1 atmosphere, a pressure less than about 1 atmosphere, and / or any other suitable pressure. The process conditions may include a temperature (e.g., reactor temperature) higher than normal room temperature (e.g., within a threshold temperature range and / or higher than a threshold temperature range, e.g., about 25 - 50 °C, about 40 - 60 °C, about 50 - 100 °C, about 50 - 75 °C, about 70 - 100 °C, and / or greater than about 100 °C, etc.), and / or a temperature (e.g., reactor temperature) higher than a temperature typically achievable in an electrolytic cell other than a gas-phase electrolytic cell. Additionally or alternatively, the process conditions may include a temperature substantially equal to room temperature (e.g., about 20 - 30 °C), a temperature less than room temperature, and / or any other suitable temperature. However, the process conditions may additionally or alternatively include any other suitable process conditions.

[0134] Higher carbon dioxide flow rates can result in an increase in the production of CCPs such as CO (e.g., due to greater availability of carbon dioxide for reduction), and consequently an increase in the CCP:H2 ratio (correspondingly, lower carbon dioxide flow rates can result in a decrease in CCP production and the CCP:H2 ratio). In some embodiments, higher carbon dioxide flow rates can also result in a decrease in carbon dioxide conversion efficiency, such that the output stream (e.g., syngas output) is diluted with unreacted carbon dioxide. For example, the carbon dioxide flow rate (e.g., measured at the reactor inlet) may be from about 0.1 to 1000 sccm / cm 2 (e.g., from about 0.1 to 1 sccm / cm 2 , from about 1 to 10 sccm / cm 2 , from about 10 to 100 sccm / cm 2 , and / or from about 100 to 1000 sccm / cm 2 ) and maintained at one or more values within the range.

[0135] In a first specific example of control based on input gas flow rate, an electrolyzer configuration A with a triple serpentine flow field is used, the electrolyzer pressure is maintained substantially at 120 psi, the current density is maintained substantially at 500 mA / cm 2 , and the electrolyzer temperature is maintained substantially at 30 °C. In this specific example, substantially pure carbon dioxide gas is input at various flow rates, and input flow rates of 12 sccm / cm 2 , 20 sccm / cm 2 , and 40 sccm / cm 2 (e.g., measured at the reactor inlet) result in CO:H2 ratios of approximately 1:1, 2:1.1, and 4:1, respectively.

[0136] In a second specific example of control based on input gas flow rate, an electrolyzer configuration A with a serpentine flow field is used, the electrolyzer pressure is maintained substantially at 130 psi, and the current density is maintained substantially at 500 mA / cm 2 . In this specific example, substantially pure carbon dioxide gas input at a flow rate of 40 sccm / cm 2 results in a CO:H2 ratio of approximately 8:2, whereas 12 sccm / cm2 results in a ratio of approximately 1:1 in the flow rates.

[0137] Higher carbon dioxide pressures can result in an increase in the CCP partial yield and / or the CCP:H2 ratio (and correspondingly, lower carbon dioxide pressures can result in a decrease in the CCP partial yield and / or the CCP:H2 ratio). First, an increase in carbon dioxide pressure can result in an increase in the availability of carbon dioxide for reduction, thereby increasing the total CCP production. Second, higher pressure in the catalyst can reduce the ingress of water into the catalyst (e.g., from the cathode), thereby reducing the amount of water available for reduction, which can directly increase the CCP:H2 ratio and / or reduce the competition and / or reaction energy at the catalytic reaction sites (e.g., thereby favoring the reduction of carbon dioxide). Thus, in some embodiments (e.g., where a high CCP partial yield and / or CCP:H2 ratio is desired), a high electrolyzer pressure (e.g., greater than 100 psi but below the carbon dioxide phase transition pressure such as the critical pressure of 1070 psi, etc.) may be employed. For example, the electrolyzer pressure may be maintained at one or more values in the range of about 1 - 1100 psi (e.g., about 1 - 10 psi, about 10 - 100 psi, about 100 - 300 psi, about 200 - 600 psi, and / or about 500 - 1100 psi), and / or may be maintained at any other suitable pressure.

[0138] In a specific example of control based on electrolyzer pressure, an electrolyzer configuration A with a single serpentine flow field is used, substantially pure carbon dioxide gas is input at about 100 sccm / cm 2 and the current density is substantially maintained at about 150 mA / cm 2 and the electrolyzer temperature is substantially maintained at about 20°C. In this specific example, the electrolyzer pressure is substantially maintained at various pressures, and electrolyzer pressures of 25, 50, 75, and 100 psi result in CO:H2 ratios of approximately 3:2, 2.4:1, 3:1, and 5:1, and CO partial yields of approximately 59%, 69%, 75%, and 84%, respectively.

[0139] An increase in the hydration of the input gas can lead to an increase in water reduction (e.g., due to an increase in the availability of water for reduction), and thus a decrease in the CCP:H2 ratio. In the case of a substantially pure carbon dioxide input, only a small amount of water reaches the catalyst (almost invariably from the cathode side of the reactor), resulting in a higher CCP:H2 ratio. In contrast, when a hydrated input gas is used, a large amount of water from the input gas can reach and react with the catalyst. For example, the input gas hydration (e.g., the proportion of water vapor in the input gas) may be maintained at one or more values in the range from 0% (e.g., substantially pure carbon dioxide, substantially unhydrated input gas) to 100% (e.g., 0 - 1, 1 - 3 percent, 3 - 5 percent, 5 - 7 percent, 7 - 10 percent, 10 - 15 percent, 15 - 25 percent, 25 - 50 percent, 50 - 75 percent, and / or 75 - 100 percent).

[0140] In a specific example of control based on the input gas hydration, an electrolyzer configuration A with a single serpentine flow field is used, the current density is maintained substantially at 50 mA / cm 2 the electrolyzer pressure is maintained substantially at 12 psi, and the electrolyzer temperature is maintained substantially at 20 °C. In this specific example, carbon dioxide gas with a varying amount of hydration is input at 100 sccm / cm 2 where a pure carbon dioxide input gas results in a CO:H2 ratio of approximately 3:2, a 12.2% hydrated input gas results in a CO:H2 ratio of approximately 1:5.67, and intermediate hydration amounts result in CO:H2 ratios between these two values.

[0141] An electrolytic cell may exhibit different regimes of CCP and H2 generation with respect to current density. In an ideal electrolytic cell, at low current density, water reduction does not occur and all the current is directed towards the reduction of carbon dioxide, resulting in a substantially linear dependence of CO generation on current and substantially no H2 generation. In contrast, at higher current density, additional current (e.g., beyond a threshold current at which substantially all of the carbon dioxide has already been consumed) is used to reduce water, resulting in a substantially linear dependence of H2 generation on the additional current and substantially constant CO generation. In many typical electrolytic cells, these ideal theories are relaxed, but two general regimes are still shown: in the low current density regime, CO generation increases much more rapidly than H2 generation and then reaches a plateau in the higher current density regime, while H2 generation increases at a higher rate. The method may comprise the step of controlling (e.g., controlling the CO:H2 ratio) CO and / or H2 generation by operating at any or all of a wide range of current densities (e.g., controlling the electrolytic cell operation within the low current density regime and / or within the high current density regime). In some embodiments, the use of gaseous phase input carbon dioxide may allow for a relatively high current density (whereas electrolytic cells using aqueous carbon dioxide solutions may be limited to a current density of tens of mA / cm 2 or lower). For example, the method may be between about 1 mA / cm 2 and 100 A / cm 2 (e.g., about 1 - 75 mA / cm 2 , about 50 - 100 mA / cm 2 , about 100 - 200 mA / cm 2 , about 200 - 500 mA / cm 2 , about 500 - 1000 mA / cm 2 , about 50 - 1000 mA / cm 2 , about 0.5 - 10 A / cm 2 , about 1 - 2 A / cm 2 , about 2 - 5 A / cm 2 , about 5 - 10 A / cm 2 , about 5 - 100 A / cm 2 , about 10 - 20 A / cm 2 , about 20 - 50 A / cm 2, a current density such as about 50 to 100 A / cm 2 , about 50 mA / cm 2 , about 65 mA / cm 2 , about 80 mA / cm 2 , about 90 mA / cm 2 , about 100 mA / cm 2 , about 110 mA / cm 2 , about 120 mA / cm 2 , about 130 mA / cm 2 , about 140 mA / cm 2 , about 150 mA / cm 2 , about 200 mA / cm 2 , about 300 mA / cm 2 , about 500 mA / cm 2 , about 700 mA / cm 2 , about 1000 mA / cm 2 , about 1500 mA / cm 2 It may include steps of operating at a threshold value such as the above, exceeding the threshold value, or less than the threshold value, and / or any other suitable current density.

[0142] In some embodiments, an increase in the electrolyzer temperature may result in a reduction in the CO:H2 ratio (e.g., by an increase in water ingress from the cathode, by an increase in the reactivity of water, etc.). The method may include steps of controlling the electrolyzer temperature within an operating range such as a range between a minimum temperature (e.g., a water freezing temperature such as 0 °C) and a maximum temperature (e.g., about 40 °C, about 50 °C, about 60 °C, about 75 °C, etc.; the water boiling temperature, e.g., 100 °C) to control the CO:H2 ratio and / or other suitable output metrics.

[0143] In a specific example of control based on the electrolyzer temperature, an electrolyzer configuration A with a quadruple serpentine flow field is used, substantially pure carbon dioxide gas is input at 70 sccm / cm 2 , the current density is substantially maintained at 150 mA / cm 2 , and the electrolyzer pressure is substantially maintained at 100 psi. In this specific example, the electrolyzer temperature is substantially maintained at various temperatures, and electrolyzer temperatures of 26.7 °C, 35 °C, 38.7 °C, and 41.9 °C result in CO:H2 ratios of about 1:0.4, 2:1, 1:1.8, and 1:3, respectively.

[0144] Additionally or alternatively, the properties of the gas diffusion layer (GDL) may be used to affect CCP and / or H2 generation. For example, the hydrophobicity of the GDL may alter H2 generation (e.g., by affecting water transport), where a more hydrophilic GDL favors H2 generation (thereby reducing the CCP:H2 ratio), and a more hydrophobic GDL inhibits H2 generation (thereby increasing the CCP:H2 ratio). Other GDL properties, such as thickness and / or pore size, may also be used to modify the reactor output.

[0145] Additionally or alternatively, the properties of the membrane (e.g., polymer electrolyte membrane) may be used to affect CCP and / or H2 generation. In an example, an anion exchange membrane that favors CCP generation can be used to achieve a high CCP:H2 ratio, a cation exchange membrane that favors H2 generation can be used to achieve a low CCP:H2 ratio, and a hybrid membrane (e.g., enabling both anion and cation transport) exhibiting various anion and cation transport properties (e.g., mobility) can be used to achieve various intermediate ratios (e.g., a membrane that favors anion transport for a higher ratio, a membrane that favors cation transport for a lower ratio).

[0146] Additionally or alternatively, catalyst properties (e.g., particle size, catalyst species, etc.) may be used to affect CCP and / or H2 generation. For example, larger catalyst particles may result in less carbon dioxide transport, thereby inhibiting CCP generation and reducing the CCP:H2 ratio, whereas smaller catalyst particles may act favorably on CCP generation, thereby increasing the ratio. Additionally or alternatively, the relative numbers of active sites with high catalyst turnover frequencies for hydrogen generation ("hydrogen sites") and active sites with high catalyst turnover frequencies for carbon dioxide reduction ("carbon dioxide sites") may depend on the catalyst particle size: larger catalyst particles typically have a higher ratio of hydrogen sites to carbon dioxide sites and act favorably on H2 generation, whereas smaller catalyst particles typically have a lower ratio and act favorably on CO generation. Additionally or alternatively, the electrolyzer output may be controlled by using the catalyst type (e.g., catalyst species), such as by employing a mixture of one or more catalyst materials. A first set of catalyst materials (e.g., gold) may act favorably on carbon dioxide reduction, and a second set of catalyst materials (e.g., platinum) may act favorably on water reduction. In an example, a substantially pure gold catalyst may be used to achieve a high CCP:H2 ratio, a substantially pure platinum catalyst may be used to achieve a low CCP:H2 ratio, and mixtures of gold and platinum with variable compositions (e.g., alloy particles, mixtures of gold particles and platinum particles, etc.) may be used to achieve various intermediate ratios (e.g., more gold for higher ratios, more platinum for lower ratios). Additionally or alternatively, the catalyst may include V, Cr, Mn, Fe, Co, Ni, Cu, Sn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Hg, Al, Si, In, Ga, Tl, Pb, Bi, Sb, Te, Sm, Tb, Ce, Nd, and / or combinations thereof. The catalyst may additionally or alternatively be associated with (e.g., bound to, supported by, incorporated into, adjacent to, in contact with, etc.) one or more support structures (e.g., support particles, support matrix, etc.), which may be a conductive support structure such as carbon, boron-doped diamond, and / or fluorine-doped tin oxide.However, the catalyst may additionally or alternatively include any other suitable material.

[0147] In a specific example of control based on catalyst particle size, a variant of electrolyzer configuration A with two catalyst particle sizes is used, both of which have the electrolyzer temperature maintained substantially at 30 °C, the electrolyzer pressure maintained substantially at 100 psi, an interdigitated flow field, and substantially pure carbon dioxide gas input at 10 sccm / cm 2 and the current density maintained substantially at 500 mA / cm 2 The first set of catalyst particles has a characteristic size of 4 nm (similar to the standard reactor configuration A), resulting in an HCR of 1:1.6 and a voltage of 3.8 V. The second set of catalyst particles has a characteristic size of 20 nm, resulting in an HCR of 1:2.8 and a voltage of 4.2 V.

[0148] Additionally or alternatively, the characteristics of electrolyzer cell compression may be used to affect CCP and / or H2 generation. In a specific example of control based on electrolyzer cell compression, an electrolyzer configuration A with two different gasket thicknesses is used (resulting in a greater pressure for the greater gasket thickness), both of which have the electrolyzer temperature maintained substantially at 30 °C, the electrolyzer pressure maintained substantially at 100 psi, a triple serpentine flow field, and substantially pure carbon dioxide gas input at 40 sccm / cm 2 and the current density maintained substantially at 500 mA / cm 2 The first gasket is 0.012 inches (0.3048 millimeters) thick, resulting in an HCR of 1:4 and a voltage of 3.6 V. The second gasket is 0.010 inches (0.254 millimeters) thick, resulting in an HCR of 1:10.1 and a voltage of 3.8 V.

[0149] Additionally or alternatively, the characteristics of the flow field can be used to affect the CCP and / or H2 generation. In a first specific example of control based on flow field characteristics, electrolyzer configuration A is used under two different sets of process conditions, both of which maintain the electrolyzer temperature substantially at 30 °C and the electrolyzer pressure substantially at 120 psi. Under the first set of conditions, an interdigitated flow field is used, and substantially pure carbon dioxide gas is input at 10 sccm / cm 2 and the current density is maintained substantially at 160 mA / cm 2 , resulting in a CO:H2 ratio of 1.6:1. Under the second set of conditions, a quadruple serpentine flow field is used, and substantially pure carbon dioxide gas is input at 40 sccm / cm 2 and the current density is maintained substantially at 120 mA / cm 2 , resulting in a CO:H2 ratio of 18.5:1.

[0150] In a second specific example of control based on flow field characteristics, electrolyzer configuration A is used under two different sets of process conditions, both of which maintain the electrolyzer temperature substantially at 30 °C, the electrolyzer pressure substantially at 100 psi, and substantially pure carbon dioxide gas is input at 40 sccm / cm 2 and the current density is maintained substantially at 500 mA / cm 2 . Under the first set of conditions, an interdigitated flow field is used and a voltage of 3.6 V is maintained substantially, resulting in a CO:H2 ratio of 1.6:1. Under the second set of conditions, a triple serpentine flow field is used and a voltage of 3.8 V is maintained substantially, resulting in a CO:H2 ratio of 10.1:1.

[0151] However, additionally or alternatively, any other suitable flow field can be employed to control the electrolyzer output, additionally or alternatively, the process conditions can include any other suitable electrolyzer conditions, and the method can additionally or alternatively comprise the step of controlling the electrolyzer output in any suitable manner. Impurity tolerance of the electrolyzer

[0152] In some embodiments, such as embodiments where the electrolyzer is operated at high pressure and / or the catalyst is held at a low voltage (e.g., a negative voltage with respect to the anode), the system and / or method may achieve high resistance to impurities and / or diluted carbon dioxide inputs, e.g., resistance to poisoning by impurities in the electrolyzer input and / or diluted inputs by species such as methane, CO, O2, and / or N2 (e.g., as compared to other carbon dioxide reactors). For example, the method may include a step of determining (e.g., always selecting such process conditions; selecting such process conditions according to the current and / or expected state of the reactor input such as the impurity state and / or dilution state, etc.) target process conditions (e.g., electrolyzer configuration such as PEM type, high target electrolyzer pressure, etc.) to achieve resistance to impurities and / or diluted inputs. These impurities may include species typically present in the electrolyzer input stream such as SO X and / or NO X (e.g., products of coal combustion and / or natural gas combustion such as the output from a coal-fired power plant or a natural gas-fired power plant), and / or may include any other suitable impurities such as ammonia, hydrogen sulfide, and mercury. In one example, the system and / or method can effectively function using an input stream containing up to 4% CO, 6% O2, 10% N2, 800 ppm NO x and / or 100 ppm SO x , and the total of the CO, O2, and N2 impurities is, for example, 10% or less.

[0153] In a specific example of dilution input resistance, an electrolyzer configuration A with a single serpentine flow field is used, the current density is substantially maintained at 160 mA / cm 2 , the electrolyzer pressure is substantially maintained at 110 psi, the electrolyzer temperature is substantially maintained at 20 °C, and carbon dioxide-containing gases with various dilution levels in methane or nitrogen are at 200 sccm / cm 2It is input with. In this specific example, the electrolyzer performance has a high tolerance to methane dilution up to at least 50% methane, where methane concentrations of 0%, 25%, and 50% result in a CO:H2 ratio in the range of 9.5:1 to 8.5:1 and a CO partial yield greater than 90%. Using 75% methane results in a greater performance reduction, with the CO partial yield reducing to approximately 84%. In this specific example, similar tolerance is observed for nitrogen dilution, where nitrogen concentrations of 0%, 25%, 50%, and 75% result in a CO:H2 ratio between 9:1 and 8:1, and a maximum nitrogen concentration of 50% results in a CO partial yield higher than 85% (a 75% nitrogen concentration results in a CO partial yield of approximately 81%).

[0154] In a specific example of impurity tolerance, an electrolyzer configuration A with a single serpentine flow field is used, and the current density is maintained substantially at 150 mA / cm 2 while the electrolyzer pressure is maintained substantially at 100 psi, the electrolyzer temperature is maintained substantially within the range between 20 °C and 25 °C, and a carbon dioxide-containing gas with various impurities is input at 100 sccm / cm 2 It is input with. In this specific example, the electrolyzer output metrics (e.g., CO partial yield) under various impurity conditions are compared with the baseline electrolyzer performance under the same conditions, but a carbon dioxide input substantially free of impurities is used. In this specific example, it is shown that the electrolyzer performance does not deviate significantly from the baseline performance with a CO concentration of 4% or lower, an NO X concentration of 800 ppm or lower, an SO X concentration of 120 ppm or lower, or an oxygen concentration of 6% or lower.

[0155] However, the system and / or method can additionally or alternatively exhibit any suitable tolerance to impurity inputs and / or dilution inputs, or can also not exhibit such tolerance.

[0156] In certain embodiments, an impurity or impurities pass through the carbon oxide reduction electrolyzer and are sent to an output stream, where they are (a) separated upstream of another chemical reactor and / or (b) passed to another chemical reactor. In embodiments where the impurity in the output stream is passed to another chemical reactor, the impurity may be used by other reactors in the chemical operations of the process. For example, hydrogen sulfide or other sulfur-containing impurities may be employed by microbial species in a downstream bioreactor. Electrolyzer Configuration Selection

[0157] One or more system configurations may be employed based on output HCR considerations, e.g., based on a desired output HCR and / or HCR range (e.g., assuming a particular set of process conditions and / or a range of acceptable process conditions).

[0158] In some embodiments, this includes receiving an input containing carbon oxides in a first electrolyzer, such as a vapor electrolyzer, and electrochemically generating a first reduction product (e.g., molecular hydrogen and / or one or more CCPs other than the carbon oxide input in the first HCR) from the input (e.g., under a first set of process conditions). The design of the first electrolyzer and the selection of its operating conditions include determining a desired HCR and / or HCR range (e.g., based on downstream reactor metrics, market price metrics, efficiency metrics, and / or any other suitable metrics), and selecting a system configuration (e.g., for a second electrolyzer) based on the first HCR and / or the desired HCR (e.g., such that the second electrolyzer outputs or can output a reduction product having an HCR close to the desired HCR for the first HCR, optionally substantially under the first set of process conditions, but additionally or alternatively under any other suitable process conditions). For example, the configuration for the second reactor may be selected such that the second electrolyzer generates a second reduction product from the input, preferably under conditions substantially matching those of the first electrolyzer (e.g., while receiving the input under the first set of process conditions), the second reduction product includes hydrogen molecules and the same CCS as the first reduction product (e.g., substantially including all species present in the first reduction product), the second reduction product defines a second HCR that is substantially different from the first HCR, and preferably the second HCR may be closer to the desired HCR than the first HCR. For this example and / or any other embodiment described herein, a substantial difference between the first HCR and the second HCR includes that the second HCR is closer to the desired HCR than the first HCR; being different from the first HCR by at least 1%, 5%, 10%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 0.5 - 5%, 2 - 10%, 5 - 25%, 20 - 50%, 40 - 80%, and / or 75 - 100% (e.g., greater than or less than the first HCR); and / or being different from the first HCR in some other manner.

[0159] In some embodiments, the step of selecting a system configuration may comprise the step of selecting one or more aspects of the PEM in order to change the output HCR, etc. Such selection may comprise the step of selecting the composition of the membrane (e.g., different polymer species) and / or microstructure, the step of selecting the layer thickness of the membrane, and / or the step of selecting any other suitable aspect of the PEM. In some examples, such selection may comprise the step of selecting the thickness of the anion exchange membrane and / or proton exchange membrane (e.g., bipolar PEMs closer to the AEM will tend to produce a lower output HCR than those closer to the proton exchange membrane). In a first specific example, the step of selecting a thinner AEM (e.g., thinner than the reference AEM thickness such as the thickness of the AEM in the first reactor, thinner than the optimized AEM thickness substantially corresponding to optimal CCP generation, etc.) can result in a reactor configured to produce a higher output HCR, whereas the step of selecting a thicker AEM (e.g., thicker than the reference AEM thickness but not thicker than the optionally optimized AEM thickness) can result in a reactor configured to produce a lower output HCR.

[0160] Additionally or alternatively, the step of selecting a system configuration may comprise the step of selecting one or more aspects of the electrolyzer catalyst (e.g., reduction catalyst, oxidation catalyst) in order to change the output HCR, etc. In some variations, the step of selecting an aspect of the electrolyzer catalyst may comprise the step of selecting the thickness of the catalyst layer (e.g., a thicker reduction catalyst will tend to produce a higher HCR). In one example, the step of selecting a thicker reduction catalyst layer (e.g., thicker than the thickness of the reference reduction catalyst layer such as the thickness of the first electrolyzer reduction catalyst layer, thicker than the optimized reduction catalyst layer thickness substantially corresponding to optimal CCP generation, etc.) may result in an electrolyzer configured to produce a higher output HCR, whereas the step of selecting a thinner reduction catalyst layer (e.g., thinner than the thickness of the reference reduction catalyst layer but not thinner than the optionally optimized reduction catalyst layer thickness) may result in an electrolyzer configured to produce a lower output HCR.

[0161] Additionally or alternatively, the step of selecting an aspect of the electrolyzer catalyst (e.g., in embodiments where the catalyst layer includes catalyst particles, such as nanoparticles, that define a porous network) may comprise the step of selecting the catalyst porosity (e.g., a more porous reduction catalyst network will tend to produce a lower HCR). In one example, the step of selecting a less porous reduction catalyst network (e.g., less porous than a reference reduction catalyst such as the porosity of the first electrolyzer reduction catalyst network, less porous than an optimized reduction catalyst that substantially corresponds to optimal CCP production, etc.) may result in an electrolyzer configured to produce a higher output HCR, whereas the step of selecting a more porous reduction catalyst (e.g., more porous than the reference reduction catalyst, but optionally not more porous than the optimized reduction catalyst) may result in an electrolyzer configured to produce a lower output HCR.

[0162] Additionally or alternatively, the step of selecting an aspect of the electrolyzer catalyst (e.g., in embodiments where the catalyst layer includes catalyst particles, such as nanoparticles, and one or more polymer electrolytes, e.g., where the catalyst particles define a porous network that includes the polymer electrolyte and / or is mixed with a medium that includes the polymer electrolyte) may comprise the step of selecting, for example, the grade of polymer electrolyte to load into the porous reduction catalyst network, thereby selecting the catalyst-to-polymer electrolyte ratio (CPR) (e.g., a higher reduction catalyst CPR will tend to produce a higher HCR). In one example, the step of selecting a higher reduction catalyst CPR (e.g., a CPR higher than a reference reduction catalyst CPR such as the CPR of the first electrolyzer reduction catalyst network, a CPR higher than an optimized reduction catalyst that substantially corresponds to optimal CCP production, etc.) may result in an electrolyzer configured to produce a higher output HCR, whereas the step of selecting a lower CPR reduction catalyst (e.g., a CPR lower than the reference reduction catalyst, but optionally not lower than the optimized reduction catalyst CPR) may result in an electrolyzer configured to produce a lower output HCR.

[0163] Additionally or alternatively, the step of selecting the catalytic mode of the electrolyzer (e.g., in embodiments where the catalyst layer includes catalyst particles, such as nanoparticles) may comprise the step of selecting a characteristic catalyst particle size (e.g., larger particle sizes may tend to produce higher HCRs). In one example, the step of selecting a larger reduction catalyst particle size (e.g., larger than that of a reference reduction catalyst such as a first electrolyzer reduction catalyst, larger than an optimized reduction catalyst substantially corresponding to optimal CCP generation, etc.) may result in an electrolyzer configured to produce a higher output HCR, whereas the step of selecting a smaller reduction catalyst particle size (e.g., smaller than that of the reference reduction catalyst but not smaller than, e.g., the particles of the optimized reduction catalyst) may result in an electrolyzer configured to produce a lower output HCR. However, additionally or alternatively, the method may comprise the step of selecting any other suitable aspect of the electrolyzer catalyst.

[0164] Additionally or alternatively, the method may comprise the step of selecting electrolyzer cell compression (e.g., lower compression may tend to result in higher HCRs and higher compression may tend to result in lower HCRs), flow field, and / or any other suitable aspect of the system.

[0165] International Publication No. WO / 2022 / 031726, published on February 10, 2022, is hereby incorporated by reference in its entirety.

[0166] For a particular application and to produce a cathode output having a specified composition, the electrolyzer design and operating conditions can be adjusted. In some implementations, one or more general principles may be applied to operate to produce the required output stream composition.

[0167] 1. Limit the availability of carbon dioxide reactants at the cathode active site and / or increase the current density at the cathode. These operating condition ranges tend to result in the following: (a) First, decreasing the availability of carbon dioxide reactants and / or increasing the current density increases the proportion of CO2 converted to CO (i.e., the CO:CO2 in the output stream increases); (b) At some point, further decreasing the availability of carbon dioxide reactants and / or increasing the current density makes the hydrogen ion reduction reaction more prominent (i.e., the H2:CO increases). An electrolyzer that can operate with a relatively low carbon dioxide input / availability may have a flow field or gas diffusion component that limits the access of carbon dioxide to the active sites on the electrolyzer cathode. In certain embodiments, such a flow field design with a non-interdigitated flow field design and a long path such as a serpentine path between the source of CO2 and the cathode results in a higher ratio of CO:H2. An interdigitated flow field forces the input gas (carbon oxide) to flow through the gas diffusion layer and then exit at different locations on the flow field. A non-interdigitated design has a long continuous path for the carbon oxide feed gas to flow into and out of the cathode. The channels on the inlet side are separated from the channels on the outlet side. In certain embodiments, a relatively thick gas diffusion electrode limits the mass transport of CO2 to the cathode active site and, therefore, tends to increase the ratio of CO:CO2 and / or H2:CO.

[0168] 2. Make hydrogen ions more available at the cathode. By making hydrogen ions more available at the cathode, a cathode product stream having a relatively high ratio of H2:CO can be produced. An electrolyzer configured to provide a relatively hydrogen-rich product may (a) deplete the carbon dioxide reactant at the cathode (as described in 1), (b) allow relatively high flow rates of hydrogen ions to be transported from the anode (where they are generated) to the cathode, and / or (c) employ a design that operates at a relatively high cell temperature. An electrolyzer that can operate with relatively high flow rates of hydrogen ions to the cathode may have a MEA with a cation-conductive polymer and / or a mixed-ion conductive polymer at the cathode. Alternatively, or in addition, in a MEA that includes a cathode buffer layer, the layer is designed to be relatively thin and / or have a relatively high hydrogen ion mobility.

[0169] 3. Make hydrogen ions less available at the cathode. When hydrogen ions are made relatively less available at the cathode, a cathode product stream having a relatively high ratio of H2:CO can be produced. An electrolyzer configured to provide a relatively hydrogen-poor product may (a) provide an excess of carbon dioxide reactant to the cathode for a given current density, (b) include a MEA design that prevents hydrogen ions from reaching the cathode, and / or (c) employ a design that operates at a relatively low cell temperature. Direct air capture of CO2

[0170] In certain embodiments, an electrolytic carbon dioxide reduction system uses carbon dioxide received directly from the air. A system for such embodiments includes a direct air CO2 capture subsystem and a carbon dioxide reduction electrolyzer subsystem. The system is configured such that CO2 from the capture subsystem is supplied to the cathode side of the electrolyzer subsystem, either directly or indirectly.

[0171] Since air is often the only major raw material, an air-capturing CO2 electrolysis system may be deployed anywhere there is space for system components. In some deployments, the system occupies relatively less dense areas. In some deployments, the system occupies dense areas. In some embodiments, the system is deployed at least partially on a vehicle or a ship. For example, the air-capturing unit may be provided on a vehicle or a ship while the carbon dioxide electrolyzer may be provided at a port or an offshore platform. In some cases, the deployment location has an energy supply, for example, a location rich in sunlight and / or wind. In some cases, the deployment location is a desert. In some embodiments, the system is deployed on a large ship such as a cargo ship or a military ship such as an aircraft carrier. In some embodiments, the energy source is provided by a solar or wind power plant associated with an offshore platform or a port while the carbon dioxide capturing unit is provided on a ship or other vessel. The carbon dioxide electrolyzer may be provided on an offshore platform or a port.

[0172] The system may be designed such that air or other gas is provided to the CO2 capture subsystem under specified conditions. In certain embodiments, a fan, a vacuum pump, or simply wind is used to deliver air to the CO2 capture subsystem.

[0173] In certain embodiments, the CO2 capture subsystem comprises two phases: a first phase (phase 1) in which air contacts an adsorbent and CO2 is removed from the air, and a second phase (phase 2) in which heat, electricity, pressure, and / or humidity is applied to the adsorbent to release CO2 and / or water.

[0174] In some implementations, the CO2 recovery subsystem employs a solid or liquid absorbent or adsorbent to recover CO2 in Phase 1. In various implementations, Phase 1 is carried out under ambient or near-ambient conditions. In Phase 2, temperature, electricity, pressure, and / or moisture swings are applied, and the absorbed or adsorbed CO2, and optionally water, are released.

[0175] In certain embodiments, the absorbent is heated to release CO2. As an example, the adsorbent is heated from an ambient temperature (e.g., about 20 - 40 °C) to at least about 75 °C to release CO2 and optionally water. In some cases, the temperature swing is from ambient temperature to about 50 - 1000 °C, or from ambient temperature to about 75 - 200 °C, or from ambient temperature to about 600 - 1000 °C. As an example, the adsorbent is heated for a duration sufficient to remove the desired proportion of CO2 and optionally water. The duration is a function of the amount of adsorbent being processed, the proportion of CO2 and / or water being removed, and the heat transfer to the adsorbent.

[0176] In certain embodiments, the absorbent is exposed to humidity to release CO2. As an example, the adsorbent is first exposed to dry air (e.g., air having up to about 50 mol% water, or up to about 30 mol% water, or up to about 5 mol% water), and subsequently exposed to moist vapor (e.g., air having at least about 75 mol% water, or at least about 90 mol% water, or about 100 mol% water).

[0177] In some embodiments, the CO2 recovery unit employs an electro-swing mechanism to recover and later release CO2. In certain cases, the electro-swing carbon dioxide unit comprises a Faradaic adsorption system including an electrochemical cell that utilizes the reductive addition of CO2 to a redox species such as quinone (e.g., 2,6-di-tert-butyl-1,4-benzoquinone), 4,4'-bipyridine, or thiolate for CO2 recovery. These redox agents may be provided in an organic electrolyte. In some cases, the electro-swing adsorption system provides a carbon dioxide recovery material on a solid support such as a carbon nanotube support and / or a zeolite support. In some cases, the electro-swing CO2 recovery unit releases CO2 by providing heat (e.g., by Joule heating) to an absorbent and / or an electrode that holds the recovered CO2.

[0178] Depending on the configuration and operating conditions of the CO2 recovery subsystem, it can produce a high concentration of CO2, e.g., about 90 mol% or more, from air. In some cases, the CO2 recovery subsystem is configured to produce CO2 at a relatively low concentration, which is still sufficient for the operation of the CO2 reduction electrolyzer.

[0179] As an example, CO2 recovery adsorbents and related subsystem components are available from Climeworks AG in Zurich, Switzerland; Global Thermostat in New York, NY; Carbon Engineering Ltd. in British Columbia, Canada; and Silicon Kingdom Holdings in Dublin, Ireland.

[0180] As shown, the recovered and subsequently released CO2 is a feedstock that is delivered directly or indirectly to the cathode side of the CO2 reduction electrolyzer. In certain embodiments, water recovered from air is also used in the feedstock of the CO2 electrolyzer.

[0181] In certain embodiments, the air capture CO2 electrolysis system is configured to operate to deliver CO2 from the direct air capture subsystem in a substantially pure stream of, for example, about 99 mole % or more of CO2. In certain embodiments, the system is configured to operate using low concentrations of CO2 in the electrolyzer, such as about 98 mole % or more of CO2, or about 90 mole % or more of CO2, or even about 50 mole % or more of CO2. In some cases, extremely low CO2 concentrations are used as the feedstock. Such concentrations are still substantially higher than the atmospheric concentration of carbon dioxide, which is about 0.035 mole %. In certain embodiments, the system is configured to operate using a CO2 concentration of about 5 mole % to 15 mole %, which is mixed with another gas such as air or nitrogen.

[0182] Depending on the type of adsorbent used in the process, water may be recovered and released along with CO2. In certain embodiments, the output of the CO2 capture subsystem is humidified CO2 that is water with a water concentration of about 0 to 20 mole %.

[0183] In certain embodiments, the output of the CO2 capture subsystem contains only CO2 and other components in air such as nitrogen, oxygen, water, argon, or any combination thereof. In all cases, CO2 is present at a concentration higher than its concentration in air. In certain embodiments, the output of the CO2 capture subsystem does not contain sulfur.

[0184] The direct air capture unit and the CO2 electrolyzer can be integrated in several ways depending on the type of air capture technology. Heat and mass transfer components may be integrated in the overall air capture CO2 electrolysis system.

[0185] For example, in some designs, the CO2 reduction electrolyzer is configured to receive CO2 from the direct air capture subsystem and provide heat and / or humidity to the direct air capture subsystem. The heat provided may release the CO2 recovered during phase 2 of the direct air capture subsystem that employs a temperature swing desorption mechanism. The humidified electrolyzer product gas can be used to release the CO2 recovered during phase 2 of the direct air capture subsystem that employs a moisture swing desorption mechanism.

[0186] In certain embodiments, the CO2 electrolyzer is designed or configured to receive diluted CO2 (e.g., CO2 at about 50 mole % or less) as an input.

[0187] The direct air capture unit can be designed using a plurality of adsorbent vessels. To receive a continuous stream of CO2 (and optionally water) from the air capture subsystem, at least two different vessels operate at different stages of sorption / desorption during the operation of the overall air capture CO2 electrolysis system. For example, while one adsorbent vessel takes in air to recover CO2, the other may be heated to release CO2; as each vessel continues through the sorption / desorption cycle, the sorption vessel that has taken in CO2 vents the CO2 and vice versa. The addition of multiple vessels at different points in the cycle allows for a continuous stream of input to be delivered to the CO2 electrolyzer and for a continuous stream of air containing CO2 and moisture and / or heat and / or vacuum to be received.

[0188] The direct air capture unit can be sized to deliver a desired volume of CO₂ flow for downstream processes such as a CO₂ electrolyzer. This can involve employing multiple adsorbent-containing vessels. For example, a direct air capture subsystem may be configured to deliver 750 slpm of CO₂. Such a subsystem can be connected to a 200-cell electrochemical stack composed of 1000 cm² membrane electrode assemblies operating at 300 mA / cm² and 3 V / cell to produce 378 slpm of CO and 42 slpm of hydrogen with a 90% current efficiency for the conversion of process CO₂ to CO. Unreacted CO₂ at the electrolyzer outlet may be recycled back to the inlet to increase carbon efficiency. Operating continuously, the combined air capture and electrolyzer unit may produce approximately 675 kg / day of CO. Generally, in some designs, an air capture CO₂ electrolyzer system is configured to output at least about 100 kg / day of CO and / or other CO₂ reduction products. In some designs, an air capture CO₂ electrolyzer system is configured to output at least about 500 kg / day of CO and / or other CO₂ reduction products.

[0189] In certain embodiments, a system that employs a carbon oxide electrolyzer and optionally direct air capture of a carbon dioxide unit also includes a module configured to recover water from air or the atmosphere. In some embodiments, the module configured to recover water from air utilizes solar energy from solar photovoltaics and / or solar thermal power generation along with a hygroscopic material. In certain embodiments, the module configured to recover water is an ambient dehumidifier such as a hydro panel (e.g., available from Zero Mass Water, Inc. of Scottsdale, Arizona). Metal formate production

[0190] Returning to FIG. 1, as shown in operation 100, the product gas from the carbon dioxide reactor 120 of the present disclosure, such as carbon monoxide, can be used in one or more downstream processes including metal formate synthesis 140. In some embodiments, intermediates, reactants, and / or by-products can be separated, purified, recycled back into the system, and reused. Examples include nitrogen 146, methanol 142, and / or methyl formate 144. In some embodiments, nitrogen and methanol are recycled.

[0191] In some implementations, the formate is an alkali metal formate such as sodium formate, potassium formate, cesium formate, or an alkaline earth metal formate such as calcium formate or barium formate. In certain embodiments, the formate is sodium formate. In certain embodiments, the formate is potassium formate.

[0192] Optionally, the produced metal formate can be further used as a reactant in the oxalate synthesis process 160 to form oxalic acid. In certain embodiments, the carbon dioxide electrolyzer and associated oxalic acid production unit are deployed within or near a cement production plant. The carbon dioxide produced at the cement factory can be used as a raw material for the carbon dioxide electrolyzer. The oxalic acid produced by the system can be used to harden the cement. In certain embodiments, the oxalic acid used in the cement produces calcium oxalate with very low solubility. The cement produced using oxalic acid can withstand degradation due to contact with acids during use (e.g., after installation or construction).

[0193] Operation 100 can produce oxalic acid in an impure form. Thus, the system may be further configured to provide the oxalic acid product to a separator, which may be configured to purify the oxalic acid and return the unreacted alcohol to the reactor. In certain embodiments, the separator is configured to perform azeotropic distillation on the oxalic acid product from the reactor.

[0194] Oxalic acid can be produced by converting a metal formate to a metal oxalate and then acidifying it. In some implementations, the process may include the following operations: (1) generating a metal formate from carbon monoxide produced by a carbon dioxide electrolyzer; (2) generating a metal oxalate from the metal formate, for example, by thermal decomposition; and (3) generating oxalic acid by exposing the metal oxalate to an acid. The overall process can be carried out as a batch process. In some cases, at least the metal formate generation operation and the metal oxalate generation operation are performed in the same container. In some examples, the formate and / or oxalate generation container may be a pressure vessel such as an autoclave. In some cases, the metal formate generation container and / or the metal oxalate generation container include a mechanism for reducing the particle size of solid reactants such as metal hydroxides. In some examples, the generation container includes a ball mill.

[0195] Figure 2 schematically shows a particular embodiment of the present invention. System 200 generates a metal formate product 238 from carbon monoxide 210 generated by a carbon dioxide electrolyzer 208. The starting materials 206 of the carbon dioxide electrolyzer 208 are carbon dioxide and water.

[0196] In the synthesis of the metal formate, the reactants are the carbon monoxide output from the carbon dioxide electrolyzer 208 and the metal hydroxide. Methanol 220 and the metal hydroxide 216 are supplied to the mixer 218 to form a solubilized hydroxide 222. The alkali metal hydroxides used in the process of the present invention can be used as solids or as solutions in suitable solvents. It is also possible to use a mixture of two or more alkali metal hydroxides. For the purposes of the present invention, the term alkali metal hydroxide includes both a single alkali metal hydroxide and a mixture of two or more alkali metal hydroxides. However, it is preferred to use only one alkali metal hydroxide.

[0197] The alkali metal hydroxide can be lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, or cesium hydroxide.

[0198] In some metal formate syntheses, carbon monoxide is provided to reactor 226 at a concentration of at least about 0.5 mole fraction, or at least about 0.8 mole fraction, or at least about 0.9 mole fraction.

[0199] Both carbon monoxide 210 and solubilized hydroxide 222 are supplied to one or more metal formate synthesis reactors 226. Then, using a suitable metal formate separation process 232, a solid metal formate product 238 and a liquid containing methanol and methyl formate 224 are recovered. The liquid is fed into separator 228. After separation, methyl formate 224 can be fed back to the formate synthesis reactor, while the recovered methanol can be purified by various techniques such as water separation 244, and thus, water 254 and purified methanol 252 are produced. The purified methanol is then recycled back to the production process by introduction into mixer 218. If two or more metal formate synthesis reactors are employed, they can be arranged in parallel, in series, or in a combination of parallel and series arrangements.

[0200] Figure 2 shows a system containing methanol as a solvent. Methanol is a suitable solvent for sodium formate production. However, if potassium formate or calcium formate is the desired output, in some embodiments, water may be used as the solvent instead of methanol. Except for replacing the solvent, the system setup and product recovery are the same as those described with respect to Figure 2.

[0201] FIG. 3 shows an embodiment of a formate production system 300 comprising a formate production reactor 326, various downstream formate recovery units, and an intermediate / by-product recycle unit. System 300 is configured to transport carbon monoxide gas output 310 from an electrolyzer to at least one formate production reactor 326 while being stepwise pressurized by a compressor from about 1 bar to about 10 bar, up to about 50 bar.

[0202] Air 301 is introduced into the system, passes through a cooling tower 305, and then is circulated through a compressor that performs stepwise pressurization of carbon monoxide 310.

[0203] Reactor 326 is configured to receive not only carbon monoxide from the electrolyzer, but also a metal hydroxide, a solvent, and a catalyst. In some embodiments, the metal hydroxide is sodium hydroxide. The solid hydroxide may be provided in various forms such as a powder. In some cases, it is optionally reduced in particle size, such as by grinding, pulverizing, or otherwise during reaction with carbon monoxide to increase the surface area of the hydroxide available for the reaction. For example, the solid hydroxide may be milled in a ball mill autoclave during contact with carbon monoxide.

[0204] In one embodiment, system 300 is configured to supply a methanol 320 solvent to the production reactor 326 and supply solid sodium hydroxide 316 to the production reactor 326 via a conveyor belt. In some embodiments, solubilization of sodium hydroxide in methanol occurs within reactor 326.

[0205] The formate production reactor 326 may, in some embodiments, be one or more reactors equipped with a stirrer. The reactor may be a stirred batch reactor and may be utilized all at once or sequentially. The stirrer within the reactor is appropriately sized and operates during the reaction time to increase the contact surface area between the vapor phase and the liquid phase.

[0206] The sodium hydroxide starting material 316 is solubilized in methanol 320 and reacts with carbon monoxide in the formate production reactor.

[0207] In certain embodiments, the carbon dioxide electrolyzer located upstream from the metal formate production reactor is configured to operate in (a) a high reduction product to hydrogen product stream operating parameter regime as described herein, and / or (b) a high reduction product to CO2 ratio operating parameter regime as described herein.

[0208] System 300 is configured to transport the formate-containing solution collected from reactor(s) 326 to a separator unit that may include filter 328 and / or dryer 332. The filter and dryer may be separate devices or may be combined in a single device. The output of the filter includes, for example, wet sodium formate that can be dried in a rotary dryer 332.

[0209] To assist the drying process, a carrier gas such as nitrogen 330 passes through dryer 332. Dried sodium formate 338 is collected from dryer 332. In some embodiments, system 300 includes a recycle path for recycling nitrogen that includes condenser 336.

[0210] In some embodiments, system 300 includes a recycle path for recovering and reusing methanol. In filter 328, methanol can be recovered, collected in storage tank 334, and then pumped to distillation column 340. The methanol output from the distillation column is condensed in condenser 342 and then pumped via pump 345 into the delivery line that carries methanol 320 to reactor 326. Additionally, in some embodiments, higher alcohol by-products 346 are present. They can be recovered by separation in distillation column 340. Air 301 is also introduced into the system along with water and heated in heater 348 to provide a heat source. The water vapor from the system can be condensed by condenser 350.

[0211] Figure 4 is an illustration of an embodiment of the present invention featuring three recycle paths: at least one path for recycling carrier gas, at least one path for recycling methanol, and at least one path for recycling methyl formate if present. System 400 is configured to transport carbon monoxide gas output 410 from the electrolyzer through compressor 412 and heater 414 to at least one formate production reactor 426.

[0212] In some embodiments, carbon monoxide reactant 410 is heated to a temperature above about 100 °C prior to introduction into reactor 426. Such preheating can be beneficial to enable a suitable temperature very early in the reaction. In some embodiments, gas 410 can be introduced into the reactor using a special nozzle (e.g., a spiral spray nozzle or a cone nozzle) or other distribution means that further increases the surface area of the carbon monoxide bubbles and improves the absorption rate.

[0213] In certain embodiments, the pressure of carbon monoxide can be about 5 MPa. In some embodiments, the higher the carbon monoxide concentration, the higher the reaction rate and the shorter the batch time. High pressure can cause the operating cost of the compressor and the capital cost of the reactor to increase, which may not be desirable.

[0214] A metal hydroxide reactant such as sodium hydroxide 416 is introduced into mixing tank 418 where it is solubilized in methanol 420. Methanol 420 passes through storage tank 422 and is then pumped into mixing tank 418. Compressor 425 is utilized to assist in pumping the recycled methanol into formate production reactor 426. In some embodiments, the methanol is not preheated prior to introduction into reactor 426 and can therefore remain in the liquid phase.

[0215] In process 400, two or more formate production reactors 426 can be utilized. In some embodiments where at least two reactors are present, they can be operated in parallel batch mode. This can be advantageous as a significant residence time is required to achieve complete conversion of the sodium hydroxide molecules. Two or more reactors can be operated alternately so that the downstream process can operate semi - continuously.

[0216] The reaction between carbon monoxide 410 and sodium hydroxide 416, which are reactants within reactor 426, can occur in a temperature range of 60 °C to 200 °C in some embodiments. The reaction temperature range in some embodiments is from about 100 °C to about 200 °C. Since the reaction is highly exothermic (-98.3 kJ / mol), the amount of methanol in the reactor should be minimized to absorb sufficient heat and exceed 100 °C. In some embodiments, the pressure can be from about 50 bar to about 100 bar. In some embodiments, the sodium hydroxide concentration is from about 10 to about 25 weight percent in methanol. In some embodiments, to avoid the need for heating or cooling during the reaction, the sodium hydroxide concentration is from about 13 to about 23 weight percent in methanol.

[0217] In some embodiments, the formate production reaction (e.g., the reaction between carbon monoxide and solid sodium hydroxide) has a residence time of at least about 15 - 60 minutes or about 20 - 40 minutes.

[0218] The limiting factor of the above - mentioned reaction is the absorption of carbon monoxide into the methanol solution containing sodium hydroxide. Since the diffusion rate of carbon monoxide into methanol is low, methods to increase the carbon monoxide absorption rate can improve the yield of the reaction.

[0219] System 400 is configured to transport a formate-containing solution collected from a reactor (or reactors) 426 to a separator unit that may include a filter 428 and / or a dryer 432. The filter and dryer may be separate devices or may be combined in a single device. The output of the filter includes, for example, wet sodium formate that can be dried in a rotary dryer 432.

[0220] To assist in the drying process, a carrier gas such as nitrogen 430 passes through the dryer 432. Dried sodium formate 438 is collected from the dryer 432. In some embodiments, system 400 includes a recycle path for recycling nitrogen that includes a condenser 436. Air 401 is introduced into a pressure swing absorber (PSA) generator and nitrogen is the PSA generator output.

[0221] In some embodiments, system 400 includes a recycle path for recovering and reusing methanol. In the filter 428, methanol can be recovered, collected in a storage tank 434, and then pumped to a distillation column 440. The methanol output from the distillation column passes through a water removal unit 444. In some embodiments, the water removal unit is one or more beds packed with desiccant particles. The packed bed can be filled with a highly selective adsorbent including a synthetic zeolite having small pores such as zeolite NaA, or a molecular sieve, or a metal-organic framework. After passing through the water removal unit 444, the methanol is purified and ready for recirculation. The recovered methanol then passes through a pump 445 and is then supplied to a storage tank 422. The filter wash methanol stream 431 is a recycle conduit for recycling methanol to the filter 428.

[0222] In some embodiments, system 400 comprises a recycle path for recovering and reusing methyl formate by-products. Methyl formate is an intermediate in the main reaction of the process. Typically, between 5 and 10% of the filter outlet stream is composed of methyl formate. Methyl formate can be recovered by distillation 440 and recycled directly to the reactor. In some embodiments, when the temperature at the highest column tray is at least about 40°C, methyl formate will be reliably included in the distillate. The distillate passes through condenser 442 and is then delivered to reactor 426.

[0223] Methyl formate 424 is not sent to mixing tank 418 because it can react with sodium hydroxide to form sodium formate, which can then cause undesirable precipitation in the mixing tank.

[0224] FIG. 5 is a schematic diagram of one embodiment of the present invention, which is a continuous process 500 including a recycle path for methanol and dryer carrier gas.

[0225] Carbon monoxide gas 510, which is a reactant generated by the carbon dioxide electrolyzer, passes through a compressor and a heater and is then supplied to formate synthesis reactor 526. Sodium hydroxide dry particles 516, which are reactants, are delivered by a conveyor belt to holding tank 562 equipped with a dosing system. Then, an appropriate amount of sodium hydroxide can be metered into mixing tank 518 equipped with a stirrer. Methanol 520 for solubilizing sodium hydroxide is also introduced into mixing tank 518.

[0226] After mixing, sodium hydroxide solubilized in methanol is pumped via pump 525 to reactor 526. Reactor 526 can be connected in series via pump 556.

[0227] The product solution exits the reactor 526 and is transported to the centrifuge 558. By centrifugation, methanol and wet sodium formate are separated from each other. Methanol passes through the surge tank 560 and is pumped to a water removal unit 544 such as an absorbent bed. The water 554 is removed, and the purified and recovered methanol is recycled back to the mixing tank 518 after cooling.

[0228] The wet sodium formate exiting the centrifuge 558 is dried in a dryer 532 such as a rotary dryer with the aid of a carrier gas such as nitrogen 530. The dried sodium formate product 538 is then collected, while the carrier gas exiting the dryer passes through the condenser 536 and is prepared for reuse in the dryer.

[0229] As described above, calcium formate can be synthesized using the same system as discussed in the previous paragraph. Continuous calcium formate production is, in certain embodiments, a three-step process that includes 1) the conversion of carbon monoxide (from a carbon dioxide reduction electrolyzer as a source) to methyl formate in the presence of methanol, 2) the hydrolysis of methyl formate to formic acid in the presence of water, and 3) the formation of calcium formate by the reaction of formic acid with calcium carbonate.

[0230] The first stage of the process is carried out in a tubular packed bed reactor at high temperature and high pressure. In some embodiments, the pressure is about 5 to about 15 bar and the temperature is about 70°C to about 150°C. In this stage, methyl formate is separated from methanol by distillation.

[0231] The second stage of the process is hydrolysis, where methanol by-products are formed and can be recycled back to the reactor as reagents for the first stage. In this stage, formic acid is separated from water by distillation to prepare formic acid at a concentration of about 15 to about 70 weight percent.

[0232] In the third stage of the process, in order to increase the reaction rate and lead the reaction to completion, calcium formate is provided under reaction conditions of ambient temperature and pressure while adding an excess of formic acid. The liquid phase recovered from the centrifuge containing dissolved calcium formate and excess formic acid can be recycled back to the reactor; on the other hand, the discharged CO2 can be recycled back to the electrolyzer.

[0233] Potassium formate can be produced in the same manner as described for the above calcium formate, except that potassium carbonate is used instead of calcium carbonate in the third stage. Controller embodiments

[0234] A metal formate production system as shown in the figures of this specification can employ a control system comprising one or more controllers and one or more controllable components such as pumps, sensors, dispensers, valves, and power supplies. Examples of sensors include pressure sensors, temperature sensors, flow sensors, conductivity sensors, voltmeters, ammeters, electrolyte composition sensors including electrochemical devices, chromatographic systems, optical sensors such as absorbance measurement tools, and the like. Such sensors may be coupled to the inlets and / or outlets of the MEA cell (e.g., in the flow field) in reservoirs for holding anode water, pure water, salt solutions, etc., and / or other components of the electrocatalytic carbon dioxide reduction system.

[0235] Among the various functions controlled by one or more controllers, there can be an inflow and / or outflow of materials to modules such as reactors, dryers, filters, distillation columns, pumps, and the like. Similarly, one or more controllers can control the temperature, pressure, and / or other process parameters of such modules. In the context of a carbon dioxide electrolyzer, the functions controlled by one or more controllers include the application of current and / or voltage to a carbon oxide reduction cell, the control of backpressure at the outlet from the cathode of such a cell, the supply of purge gas to the cathode inlet, the delivery of carbon oxide to the cathode inlet, the humidification of carbon oxide in the cathode feed stream, the inflow of anode water to and / or from the anode, and the controller anode feed composition. Any one or more of these functions may have a dedicated controller for controlling that function alone. Any two or more of these functions may share a controller. In some embodiments, a controller hierarchy is employed in which at least one master controller provides commands to two or more component controllers. For example, the system may comprise a master controller configured to provide high-level control commands to (i) a power supply to a carbon oxide reduction cell, (ii) a cathode feed stream flow rate controller, and (iii) an anode feed stream flow rate controller.

[0236] The controller may include any number of processors and / or memory devices. The controller may include control logic such as software or firmware, and / or may execute instructions provided from another source. The instructions may be executed by a computer-executable component such as one integrated into a communication system. The computer-readable medium may be within any suitable computer-readable medium such as RAM, ROM, flash memory, EEPROM, optical devices (CD or DVD), hard drive, floppy drive, or any suitable device.

[0237] Prior to, during, and after unit operations such as reducing carbon oxides, a controller may be integrated with an electronic device to control the operation of any component, including an electrolytic cell. The controller may control various components or sub-parts of one or more electrolytic carbon reduction systems. Depending on the processing requirements and / or the type of system, the controller may be programmed to control any of the processes disclosed herein, such as gas delivery, temperature setting (e.g., heating and / or cooling), pressure setting, power setting (e.g., voltage and / or current delivered to the electrodes of the MEA cell), liquid flow rate setting, fluid delivery setting, and administration of purified water and / or salt solution. These controlled processes may be connected or interfaced with one or more systems that function in cooperation with the electrolytic carbon reduction system.

[0238] In various embodiments, the controller includes an electronic device comprising various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, and controls the operations described herein. The integrated circuits may include a chip in the form of firmware that stores program instructions, a digital signal processor (DSP), a chip defined as an application-specific integrated circuit (ASIC), and / or one or more microprocessors, or a microcontroller that executes program instructions (e.g., software). The program instructions may be instructions transmitted to the controller in the form of various individual settings (or program files) that define operating parameters for executing a process in one or more components of the electrolytic carbon reduction system. In some embodiments, the operating parameters may be part of a recipe defined by a process engineer to execute one or more processing steps during the generation of specific reduction products such as carbon monoxide, metal formate, methyl formate, and / or other compounds. In one example, a programmable logic controller (PLC) controls individual components of the system.

[0239] In some implementations, the controller may be integrated with the system, connected to the system, network-connected to the system in some other way, or be part of a computer or connected to that computer in which combinations thereof are made. For example, the controller may utilize instructions stored remotely (e.g., in the "cloud") and / or be executed remotely. The computer may monitor the current progress of unit operations such as electrolysis operations by enabling remote access to the system, examine the history of past electrolysis operations, examine trends or performance metrics from multiple electrolysis operations, and change the parameters of the current process, set the processing stage to follow the current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system via a network that may include a local network or the Internet. The remote computer may include a user interface that enables the input or programming of parameters and / or settings, and the parameters and / or settings are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each of the processing stages that are to be executed during one or more operations.

[0240] The controller may be distributed, such as by including one or more separate controllers that are network-connected together and function towards a common purpose such as the application of current to the MEA cell and other process control as described herein. An example of such a distributed control system for such a purpose may include one or more processors on a system for the electroreduction of carbon dioxide, and one or more processors that are remotely located and combined (e.g., at the platform level or as part of a remote computer) to control the process.

[0241] Various related computational elements, including controllers and processors, memories, instructions, routines, models, or other components, are often described or claimed as "configured to" perform a task. In such a context, the expression "configured to" is used to indicate structure by showing that a component includes a structure that performs a task or tasks during operation (e.g., stored instructions, circuitry, etc.). Thus, a controller and / or related components can be said to be configured to perform a task even if the specified component is not necessarily currently operating (e.g., is off).

[0242] Controllers and other components "configured to" perform an operation may be implemented as hardware, which may include, for example, circuitry, a memory storing program instructions executable to implement the operation, etc. Additionally, controllers and other components "configured to" perform an operation may be implemented as hardware operated by software and / or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate so as to be capable of performing the described task. Additionally, "configured to" may refer to one or more memories or memory elements storing computer-executable instructions for performing the described task. Such memory elements may include memory on a computer chip having processing logic.

[0243] Non-computational elements such as reactors, such as electrolytic cells, membrane assemblies, layers, and catalyst particles, may also be "configured" to perform a specific function. In such a context, the expression "configured to" indicates that the structure referred to has one or more features that enable the performance of the function. Examples of such features include physical and / or chemical properties such as dimensions, composition, porosity, etc. Conclusion

[0244] Although omitted for brevity, embodiments of the system and / or method can include any combination and permutation of various system components and various method processes, and one or more instances of the methods and / or processes described herein can be performed asynchronously (e.g., sequentially), simultaneously (e.g., in parallel), or in any other suitable order by and / or using one or more instances of the systems, elements, and / or entities described herein.

[0245] The figures illustrate the architecture, functionality, and operation of possible implementations of the disclosed embodiments, exemplary configurations, and variations thereof, of systems, methods, and computer program products. In this regard, each block in the block diagrams can represent a module, a group of modules, a segment, or a module, and can embody one or more steps or operations. It should also be noted that in some alternative implementations, the functions described in the block diagrams may be performed in a different order than that shown in the figures. For example, two blocks shown in succession may actually be performed substantially simultaneously, or depending on the functions involved, the blocks may be performed in the reverse order.

[0246] For purposes of clarity of understanding, although the above embodiments have been described in some detail, it will be apparent that certain changes and modifications can be made within the scope of the appended claims. Note that there are many alternative ways to implement the processes, systems, and apparatus of this embodiment. Accordingly, this embodiment should be regarded as illustrative and not restrictive, and the embodiments are not limited to the details given herein.

[0247] Those skilled in the art will recognize that modifications and changes can be made to the disclosed embodiments of the present disclosure from the foregoing detailed description, and from the figures and claims, without departing from the scope of the present disclosure as defined in the following claims.

Claims

1. (a)A carbon dioxide reduction electrolyzer having a membrane electrode assembly including one or more ion conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) (i)A carbon monoxide feed produced by the carbon dioxide reduction electrolyzer, and (ii)A methanol feed containing a metal hydroxide At least one formate synthesis reactor configured to receive; (c)A metal formate separator configured to separate and purify the metal formate produced by the formate synthesis reactor; and (d)A recycling path for recycling the recovered methanol to the at least one formate synthesis reactor A system for producing metal formate, comprising.

2. The system according to claim 1, further comprising a carbon monoxide heater and a carbon monoxide compressor configured to heat and compress the carbon monoxide before introduction into the at least one formate synthesis reactor.

3. The system according to claim 1, further comprising a methanol pump configured to transport methanol before introduction into the at least one formate synthesis reactor.

4. The metal formate separator has a filter connected to a dryer, wherein the filter is configured to receive the output from the at least one formate synthesis reactor, wherein the output comprises metal formate, methanol, and optionally methyl formate, and wherein the dryer comprises an inlet for receiving the metal formate from the filter and an outlet for removing the dried metal formate; and A gas inlet for supplying a carrier gas and a gas outlet for removing the dryer exhaust gas containing methanol. The system according to claim 1.

5. The system according to claim 4, wherein the output comprises metal formate, methanol and methyl formate.

6. The system according to claim 5, wherein the recycling path includes a distillation column configured to separate the liquid and / or gas output from the metal formate separator into the recovered methanol and the recovered methyl formate.

7. The system according to claim 5, wherein the metal formate separator includes a filter having a filtrate outlet connected to a distillation column, and the distillation column is configured to produce the recovered methyl formate and the purified methanol.

8. The system according to claim 7, further comprising a path for introducing the recovered methyl formate into the at least one formate synthesis reactor.

9. The system according to claim 8, wherein the at least one formate synthesis reactor further includes an inlet for receiving the recovered methyl formate.

10. The system according to claim 4, wherein the carrier gas is nitrogen gas.

11. The system according to claim 4, further comprising a condenser configured to purify the dryer exhaust gas containing methanol to produce a purified carrier gas and a liquid methanol-containing process stream, wherein the purified carrier gas is recycled to the dryer.

12. The system according to claim 11, further comprising a methanol separator connected to the condenser, wherein the methanol separator is configured to separate and purify methanol from the liquid methanol-containing process stream to produce purified methanol.

13. The system according to claim 12, wherein the methanol feed further includes the purified methanol.

14. The system according to claim 12, wherein the methanol separator includes a distillation column, a water removal unit, or a combination thereof.

15. The system according to claim 12, wherein the methanol separator includes a water removal unit.

16. The system according to claim 15, wherein the water removal unit is a packed bed of desiccant particles.

17. The system according to claim 1, wherein the at least one formate synthesis reactor includes a first formate synthesis reactor and a second formate synthesis reactor.

18. The system according to claim 17, wherein the first formate synthesis reactor and the second formate synthesis reactor are batch reactors and are configured to be used alternately.

19. The system according to claim 1, wherein the at least one formate synthesis reactor includes at least two formate synthesis reactors configured in series to operate continuously.

20. The system according to claim 19, wherein the metal formate separator includes a centrifuge.

21. The system according to claim 1, wherein the at least one formate synthesis reactor is equipped with a stirrer.

22. The system according to claim 1, wherein the at least one formate synthesis reactor is provided with a carbon monoxide inlet nozzle configured to enhance the reactivity of carbon monoxide.

23. The system according to claim 1, wherein the metal hydroxide is sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof.

24. The system according to claim 1, further comprising a mixing tank for solubilizing the metal hydroxide in methanol to produce the methanol feed, wherein the mixing tank is connected to the at least one formate synthesis reactor via a pump.

25. The system according to claim 1, wherein the carbon dioxide reduction electrolyzer and the at least one formate synthesis reactor are arranged within a single plant.

26. The system according to claim 4, wherein the dryer and the filter are combined into a single unit.

27. The system according to claim 1, further comprising an oxalate synthesis reactor configured to convert the metal formate to a metal oxalate, and the system is further configured to transport the metal formate to the oxalate synthesis reactor.

28. The system according to claim 27, wherein the system is further configured to contact the metal oxalate with an acid, thereby producing oxalic acid.

29. The system according to claim 27, wherein the oxalate synthesis reactor includes a pressure vessel.

30. The system according to claim 27, wherein the oxalate synthesis reactor is configured to receive a metal carbonate catalyst and perform a reaction to convert the metal formate to the metal oxalate.

31. (a) reducing carbon dioxide to carbon monoxide in a carbon dioxide reduction electrolyzer having a membrane electrode assembly including one or more ion-conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) reacting the carbon monoxide produced by the carbon dioxide reduction electrolyzer with a metal hydroxide in methanol in at least one formate synthesis reactor to produce a metal formate; (c) separating and purifying the metal formate produced in (b); and (d) recycling methanol to the at least one formate synthesis reactor A method for producing a metal formate, comprising:

32. The method according to claim 31, wherein the at least one formate synthesis reactor includes at least two batch formate synthesis reactors, and the step of reacting carbon monoxide generated by the carbon dioxide reduction electrolytic cell with a metal hydroxide in methanol is alternately carried out in the at least two batch formate synthesis reactors.

33. The method according to claim 31, wherein the at least one formate synthesis reactor includes at least two batch formate synthesis reactors, and the step of reacting carbon monoxide generated by the carbon dioxide reduction electrolytic cell with a metal hydroxide in methanol is continuously carried out in the at least two batch formate synthesis reactors.

34. The method according to claim 31, wherein the step of reacting the carbon monoxide with the metal hydroxide is carried out at a reaction temperature of about 60°C to about 200°C and a pressure of about 1 MPa to about 10 MPa.

35. The method according to claim 31, wherein the metal hydroxide has a concentration of about 1 to about 25 weight percent of the metal hydroxide in the methanol.

36. The method according to claim 31, further comprising the step of preheating the carbon monoxide from (a) before the reaction in (b).

37. The method according to claim 34, wherein the carbon monoxide is preheated to at least about 100°C.

38. The method according to claim 31, wherein the reaction temperature is about 100°C to about 200°C.

39. The method according to claim 31, further comprising the step of generating methyl formate when reacting carbon monoxide with the metal hydroxide in (b).

40. The method according to claim 39, further comprising the steps of recovering the methyl formate by distillation and recycling the methyl formate to the at least one formate synthesis reactor.

41. The method according to claim 31, wherein (c) comprises the steps of drying the metal formate using a carrier gas and generating a dried metal formate and a dryer exhaust gas stream.

42. The method according to claim 41, further comprising the step of condensing a liquid from the dryer exhaust gas stream to form a condensed liquid.

43. The method according to claim 42, further comprising the step of distilling the condensed liquid to obtain a recovered methanol.

44. The method according to claim 43, wherein the step of recycling methanol to the at least one formate synthesis reactor includes the step of recycling the recovered methanol to the formate synthesis reactor.

45. The method according to claim 31, wherein (d) further includes water removal.

46. The method according to claim 42, further comprising the steps of recovering the released carrier gas; and recycling the released carrier gas to a dryer.

47. The method according to claim 41, wherein the carrier gas is nitrogen gas.

48. The method according to claim 31, wherein the metal hydroxide is sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof.

49. The method according to claim 31, further comprising the step of converting the metal formate to a metal oxalate.

50. The method according to claim 49, further comprising the step of contacting the metal oxalate with an acid to produce oxalic acid.

51. The method according to claim 49, wherein the step of converting the metal formate to the metal oxalate is carried out at a pressure above atmospheric pressure.

52. The method according to claim 49, wherein the step of converting the metal formate to the metal oxalate includes the step of contacting the metal formate with a metal carbonate catalyst.

53. Reducing carbon dioxide to carbon monoxide in a carbon dioxide reduction electrolyzer comprising a membrane electrode assembly having one or more ion-conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; Mixing a metal hydroxide in methanol in a mixing tank to obtain a metal hydroxide solubilized in methanol; Supplying the carbon monoxide produced in (a) to at least one formate synthesis reactor, wherein the carbon monoxide is supplied to the formate synthesis reactor at a pressure of about 1 MPa to about 10 MPa together with the metal hydroxide solubilized in methanol; (d) reacting the carbon monoxide with the metal hydroxide solubilized in methanol at a reaction temperature of about 60 °C to about 200 °C to produce a metal formate; Outputting a metal formate-containing stream containing metal formate, methanol and optionally methyl formate from the at least one formate synthesis reactor; (f) Filtering the metal formate-containing stream produced in (e) to obtain solid metal formate and a filtrate containing methanol and optionally methyl formate; (g) Drying the solid metal formate produced in (f) in a dryer with a carrier gas to produce a dried metal formate and an exhaust gas stream containing methanol and the carrier gas; and (h) Distilling the filtrate to produce methanol for recycling to the mixing tank and optionally methyl formate for supply to the formate synthesis reactor A process for producing metal formate, comprising:

54. The process according to claim 53, further comprising purifying the exhaust gas stream of (g) to obtain a recovered carrier gas and recycling the recovered carrier gas to the dryer.

55. The process according to claim 53, wherein the solubilized metal hydroxide contains about 1 to about 25 weight percent of metal hydroxide in methanol.

56. The process according to claim 53, further comprising preheating the carbon monoxide produced in (a) before (c).

57. The process according to claim 56, wherein the carbon monoxide produced in (a) is preheated to at least 100 °C.

58. The process according to claim 53, wherein the reaction temperature in (d) is about 100 °C to about 200 °C.

59. The process according to claim 53, wherein the carrier gas is nitrogen gas.

60. The process according to claim 53, wherein the metal hydroxide is sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof.

61. (a) Reducing carbon dioxide to carbon monoxide in a carbon dioxide reduction electrolyzer comprising a membrane electrode assembly having one or more ion-conductive polymer layers and a cathode catalyst for promoting the chemical reduction of carbon dioxide to carbon monoxide; (b) Reacting the carbon monoxide produced by the carbon dioxide reduction electrolyzer with methanol in at least one methyl formate synthesis reactor to produce methyl formate, and then separating and purifying the methyl formate; (c) Hydrolyzing the methyl formate to formic acid using water in at least one methyl formate hydrolysis reactor, and then separating and purifying the formic acid; (d) Reacting the formic acid with a metal carbonate to produce a metal formate; and (e) Recycling the methanol from step (b) and the water from step (c) to the at least one methyl formate synthesis reactor, and recycling the water from step (c) to the at least one methyl formate hydrolysis reactor comprising wherein the metal formate is calcium formate or potassium formate, and the metal carbonate is calcium carbonate or potassium carbonate A method for producing a metal formate

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