Systems and methods for carbon dioxide reactor control

Abstract

To provide a new and useful system and a method for controlling reactors in the field of carbon dioxide reactors.SOLUTION: A method of controlling a carbon dioxide reactor preferably comprises: a step for selecting aspects of a carbon dioxide reactor based on a desired output composition; a step for producing the desired output composition by operating the carbon dioxide reactor under a controlled process condition; and / or a step for changing the output composition by changing the process condition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority to U.S. Provisional Application No. 62 / 619,996, filed January 22, 2018, U.S. Provisional Application No. 62 / 620,109, filed January 22, 2018, and U.S. Provisional Application No. 62 / 685,771, filed June 15, 2018, each of which is incorporated by reference in its entirety. [Statement of Government Support]

[0002] This invention was made with government support under Award No. 1738554 awarded by the National Science Foundation, and Award Nos. DE-SC0015872, DE-SC0017725, and DE-SC0018549 awarded by the Department of Energy, Office of Science. The government has certain rights in this invention.

[0003] The present invention relates generally to the field of carbon dioxide reactors, and more particularly to novel and useful systems and methods for reactor control in the field of carbon dioxide reactors. [Background technology]

[0004] Typical systems and methods for carbon dioxide reactor control focus on maximizing aspects of carbon monoxide (CO) and / or other carbon-containing product (CCP) production, such as maximizing the ratio of CO to other reactor products (e.g., CO:H ratio), CO concentration, and / or total or rate CO output.

[0005] Therefore, there is a need in the field of carbon dioxide reactors to create new and useful systems and methods for reactor control. [Brief explanation of the drawings]

[0006] [Figure 1]FIG. 1 is a flow chart diagram of an embodiment of a method.

[0007] [Figure 2A] FIG. 1 is a schematic diagram of one embodiment of a system. [Figure 2B] FIG. 10 is a schematic diagram of a modified example of the embodiment.

[0008] [Figure 2C] 1 is a schematic diagram of a first example embodiment of a system. [Figure 2D] FIG. 10 is a schematic diagram of a second example embodiment of the system.

[0009] [Figure 3] FIG. 1 is a schematic diagram of an example system.

[0010] [Figure 4A] 1 is an example of the ideal dependence of reactor power on current density. [Figure 4B] 1 is an example of the non-ideal dependence of reactor power on current density. DETAILED DESCRIPTION OF THE INVENTION

[0011] DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use the invention. 1. Overview

[0012] Systems and / or methods for carbon dioxide reactor control preferably function to control aspects of reactor production, such as, for example, aspects related to the amount, concentration, and / or ratio of reactor products. Typical systems and methods for carbon dioxide reactor control have focused on maximizing aspects related to the production of carbon monoxide (CO) and / or other carbon-containing products (CCPs) (e.g., carbon-containing species (CCSs)), such as the ratio of CO to other reactor products (e.g., CO:H ratio), CO concentration, and / or total or rate CO output.

[0013] However, the inventors have discovered that for some applications, simply maximizing aspect values ​​may not be desirable, and that it may be beneficial to selectively control such aspects (e.g., dynamic or selective aspect control to meet specific values ​​within a target aspect value range) rather than simply maximizing them. For example, it may be desirable to selectively control the CO:H ratio of the reactor product (e.g., to allow for selective control within a spectrum ranging from the maximum CO:H ratio possible for a particular system and / or process down to a CO:H ratio of about 1:3 or less). With such control, reactor output can be more efficiently used (e.g., reactor output can be fed directly to a subsequent input, etc.) for applications such as the production of liquid hydrocarbons via a Fischer-Tropsch process (e.g., controlling a reactor to provide a CO:H output ratio of about 1:2), via a chemical synthesis process, and / or via a gas (e.g., syngas) fermentation process (e.g., bioreactor). 2. System

[0014] The system may include a carbon dioxide reactor (e.g., as shown in Figures 2A-2D), such as a reactor that produces carbon-containing products (e.g., CO, alkanes, alcohols, etc.) and / or hydrogen from an input (preferably an input stream such as a fluid stream) that includes carbon dioxide. Preferably, the reactor receives a gas-phase carbon dioxide input and / or performs a reaction using gas-phase carbon dioxide (e.g., is a gas-phase reactor), but may additionally or alternatively 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. Preferably, the reactor is an electrolytic cell (e.g., an electrochemical reactor), more preferably a gas-phase polymer electrolyte membrane electrolytic cell, but may additionally or alternatively include any other suitable reactor.

[0015] Preferably, the reactor includes one or more of an electrode (e.g., an anode, a cathode), a catalyst (e.g., in and / or near the cathode and / or anode), a gas diffusion layer (e.g., near the cathode and / or anode), and / or a flow field (e.g., one or more channels defined in or near the electrode and / or gas diffusion layer, across the gas diffusion layer facing the cathode, etc.). In some embodiments, the reactor includes one or more polymer electrolyte membranes (PEMs), preferably providing ionic transport between the anode and cathode of the reactor. In one variation, the reactor includes a membrane stack including a cathode layer comprising a reduction catalyst and an ion-conducting polymer; a PEM membrane (e.g., a bipolar membrane, a monopolar membrane, etc.; a membrane comprising 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-conducting polymers; a membrane comprising one or more buffer layers, etc.); and an anode layer comprising an oxidation catalyst and an ion-conducting polymer. The ion-conducting polymers in each layer may be the same or different ion-conducting polymers.

[0016] In some embodiments, one or more of the catalysts (e.g., reduction catalyst, oxidation catalyst) may comprise catalytic particles (e.g., defining a porous network composed of particles), preferably nanoparticles. Additionally or alternatively, one or more of the catalysts may comprise one or more polymer electrolytes, preferably mixed with the catalytic nanoparticles (e.g., disposed within the porous network, e.g., loaded into open areas defined by the porous network). The catalytic nanoparticles may 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 may define porosity (e.g., fraction of void space within the porous network), density, circuitousness (e.g., characteristic path length, area, and / or volume per layer thickness, such as paths through the void space or paths along interconnected particles), and / or any other suitable porous network metric.

[0017] In one example ("Reactor Configuration A"), the system includes a carbon fiber paper gas diffusion layer (e.g., Sigracet 39BC); a catalyst layer including about 20% by weight of about 4 nm gold particles on Vulcan carbon and an anion-conducting polymer (e.g., Fumasep FAA-3); a bipolar PEM; and a flow field, such as a single, double, triple, or quadruple serpentine flow field or interconnected flow fields. In a specific example, the electrodes are spaced apart from each other by about 25 cm. 2 , but any other suitable area may be defined additionally or alternatively.

[0018] In some embodiments, the reactor includes one or more elements such as those described in U.S. patent application Ser. No. 15 / 586,182, filed May 3, 2017, entitled "Reactor with Advanced Architecture for Electrochemical Reaction of CO, CO, and Other Compounds," which is incorporated by reference in its entirety. However, additionally or alternatively, the reactor may include any other suitable elements in any suitable arrangement.

[0019] Additional information regarding optional embodiments and / or elements of the system and / or method (eg, as shown illustratively in FIG. 3) is provided below.

[0020] Optionally, the system of the present invention may include an upstream source of carbon dioxide input connected to the input of the carbon dioxide reactor of the present invention, the upstream source including one or more of: a biogas production system; an ethanol fermentation system such as a corn ethanol production system, a beer production system, a wine production system, etc.; a natural gas processing system; a cement production system; a blast furnace system such as a steel blast furnace system capable of producing blast furnace gas; a coke gas production system; a power plant system such as an oil power plant system, a natural gas power plant system, a coal power plant system, etc.; an oil refinery system; an ethylene production system; an ammonia production system; a hydrogen production system such as a water-gas shift system; a natural gas processing plant (e.g., Benfield process); an ethylene oxide production system; an aluminum smelting system; a liquefied natural gas (LNG) production system; a solid feedstock gasifier (e.g., municipal solid waste, biomass, or coal feedstock); a reformer (e.g., a steam methane reformer, an autothermal reformer); a system for performing a Boudouid reaction; a direct air capture (DAC) carbon dioxide process; and / or any other system capable of producing carbon dioxide. An upstream source of carbon dioxide may be connected directly to the input of the carbon dioxide reactor of the present invention (e.g., connected to the reduction catalyst via a cathode flow field and / or gas diffusion layer, etc., and thus serving as an input), or alternatively, the upstream source may be connected, in any order, to a purification system; a gas compression system; or both a purification system and a gas compression system, which are then connected to the input of the carbon dioxide system of the present invention. Multiple purification and / or gas compression systems (e.g., scrubbers, etc.) may be used.

[0021] The system of the present invention may further include an input of a downstream system capable of converting the chemical output from the carbon dioxide reactor of the present invention, connected to the output of the carbon dioxide reactor of the present invention. The downstream system of the present invention may include one or more of a bioreactor system; a Fischer-Tropsch system; an anaerobic fermentation system; a syngas fermentation system; a polyketone production system; a formate production system; a formate ester production system; a formamide production system; a hydroformylation system, a methanol synthesis system, an ethylene polymerization system; and / or any other system capable of converting the chemical output from the carbon dioxide reactor of the present invention. The carbon dioxide reactor output of the present invention may be directly connected to the downstream system (e.g., via a cathode flow field and / or a gas diffusion layer), and / or the carbon dioxide reactor 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, and then preferably connected to the input of the downstream system. Multiple purification systems and / or gas compression systems may be used.

[0022] The downstream system of the present invention may produce other product outputs in addition to the carbon dioxide output. The system of the present invention may further include a connection between the carbon dioxide-containing output of the downstream system and the input of the carbon dioxide reactor. The carbon dioxide-containing output of the downstream system may be connected directly 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, and then connected to the input of the carbon dioxide reactor of the present invention. Multiple purification systems and / or gas compression systems may be used.

[0023] The carbon dioxide reactors of the present invention may produce a range of products (e.g., methane, ethylene, carbon monoxide (CO), molecular hydrogen (H), ethanol, formate, formic acid, acetate, acetic acid, propanol, butanol, ethane, methanol) that can be used in downstream systems and processes. Different carbon dioxide reactors (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) may be used to obtain different reduction products (e.g., product compositions such as HCR), which may additionally or alternatively be obtained by adjusting operational parameters and / or otherwise. Many potential downstream systems and processes (e.g., methane bioutilization, formic acid or formate bioutilization, acetic acid or acetate bioutilization, Fischer-Tropsch, methanol synthesis, by way of example) release CO. In many of these cases, using a carbon dioxide recycle system appropriately sized for the particular application, CO from the downstream system output may be returned to the input of the carbon dioxide reactor of the present invention, increasing the carbon efficiency of the overall process.

[0024] The system of the present invention may further include a source of electrical energy connected to the carbon dioxide reactor of the present invention, and the source of electrical energy may include one or more of a solar power system; a wind power system; a geothermal power system; a fossil fuel power system; or any other system capable of generating electrical energy.

[0025] The system of the present invention may be used to store electrical energy in the form of chemical energy. For example, a power producer may generate excess power during off-peak usage periods. The system of the present invention can quickly respond to needs to consume the excess power. The system does not require warm-up for operation, and the system may be cycled between power-on and power-off states without degradation of the carbon dioxide reactor of the present invention. The ability to quickly respond to power usage needs allows the system of the present invention to work well with intermittent power sources, such as solar and wind power systems.

[0026] One embodiment of the system of the present invention may include an upstream bioreactor, a carbon dioxide reactor, 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 detection means may be used to start the carbon dioxide reactor. The system may also accelerate 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 reactor of the present invention.

[0027] The systems of the present invention may further include means (e.g., sensors, systems, etc.) for measuring the conditions, outputs, and inputs of the system connected to the carbon dioxide reactor of the present invention. Such means may include a chemical property measurement system such as a gas chromatograph, mass spectrometer, infrared spectrometer, visible spectrometer, and / or ultraviolet spectrometer; temperature detection means; flow measurement means; power availability detector; and / or any other monitoring system. The monitoring system may monitor parameters of the input and / or output streams, parameters of components of the input and / or output streams (e.g., impurity concentration, carbon dioxide concentration, product concentration, etc.), and / or any other suitable parameter of the stream.

[0028] The systems of the present invention may further include means for responding to conditions measured in systems (e.g., sensors, systems, etc.) connected to the carbon dioxide reactors of the present invention. Such means may include systems for adjusting flow rate, temperature, power consumption, or other system parameters.

[0029] The systems of the present invention may include one or more carbon dioxide reactors.

[0030] However, additionally or alternatively, the system may include any other suitable elements in any suitable arrangement. 3. Method

[0031] Preferably, the method is implemented using the system described above, although additionally or alternatively, the method may be implemented using any other suitable system. Preferably, the method includes operating a reactor under controlled process conditions (e.g., as described in more detail below) to produce desired outputs (e.g., CO, H, etc.) in desired ratios (e.g., molecular hydrogen to CCP ratio (HCR) and / or molecular CCP to hydrogen ratio), and / or varying the process conditions to vary the outputs and / or output ratios (e.g., as shown in FIG. 1).

[0032] Operating a reactor may include providing one or more inputs (e.g., gases, liquids, solids, etc.), such as carbon dioxide, a carbon dioxide source (e.g., waste gas), and / or water; reacting all or a portion of the inputs (e.g., by applying a voltage to electrodes of the device) to produce products; and / or removing the products from the reactor (e.g., as an output gas stream). Such reactions may include, for example, reducing carbon dioxide and / or water to produce products such as CO (and / or other CCPs, such as formic acid, methanol, glyoxal, methane, acetic acid, glycolaldehyde, ethylene glycol, acetaldehyde, ethanol, ethylene, hydroxyacetone, acetone, aryl alcohols, propionaldehyde, n-propanol, etc.), H, and / or O. However, operating a reactor may additionally or alternatively include causing any other suitable reactions and / or may additionally or alternatively include any other suitable elements carried out in any suitable manner.

[0033] A method may include controlling a system to achieve a desired set of process conditions (e.g., multiple aspects), such as process conditions known to result in a desired output metric value (e.g., a desired CCP:H ratio, such as a CO:H ratio). The method may additionally or alternatively include modifying the process conditions (e.g., to reduce or eliminate the difference), such as based on a difference between the actual output and the desired output. For example, the method may include imposing an initial set of process conditions; monitoring one or more output metrics (e.g., CCP:H ratio); determining that the output metric differs from a target output metric (e.g., greater than or less than the target); modifying one or more process conditions to reduce the difference in the output metric (e.g., reducing or increasing a process condition value, such as a condition where the output metric tends to increase or decrease with increasing process condition value); and optionally continuing to monitor the output metric and / or modify the process conditions (e.g., performing closed-loop control of the process conditions based on the output metric).

[0034] Optionally, the method may include determining a target output metric, which functions to determine which parameters or aspects (e.g., critical parameters for a particular application or downstream system) should be targeted. One or more target output metrics may be selected for a particular process. The target output metric may be an output metric associated (e.g., predetermined, prescribed, etc.) with the application (e.g., an application described above, such as a Fischer-Tropsch process), a randomly selected output metric, an empirically determined output metric (e.g., through iterative testing and monitoring of downstream application performance), an optimized output metric (e.g., based on downstream application operating parameters, reactor operating parameters, etc.), a user-specified output metric, and / or an otherwise determined output metric.

[0035] Optionally, the method may include determining a target value for the target output metric, which serves to identify a target value (from a range of values). In some variations, the target value may be a maximum or minimum value (e.g., a maximum feasible 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 may be a value associated with (e.g., predetermined, pre-associated with) the application; a randomly selected value; an empirically determined value (e.g., through iterative target value selection, through monitoring performance of a downstream application and adjusting the target value based on the performance of the application); an optimized value (e.g., based on operational parameters of a downstream application, based on reactor operational parameters, etc.); or a value determined in any other manner. However, the target value may be any other suitable value and may be determined in any suitable manner.

[0036] Under some conditions, the method may achieve carbon dioxide conversion (e.g., fractional CO yield) of greater than 95% (e.g., up to 100%), e.g., a system operated under such conditions may achieve at least that threshold conversion metric. However, additionally or alternatively, the method may include steps of achieving greater than 50%, 60%, 70%, 80%, 90%; carbon dioxide conversion within the range of 10% to 100%, e.g., 10% to 40%, 30% to 50%, 40% to 60%, 50% to 70%, 60% to 75%, 70% to 85%, 80% to 95%, 90% to 95%, 92% to 98%, and / or 95% to 100%; and / or any other suitable carbon dioxide conversion.

[0037] Preferably, the method includes providing the reactor product (or a subset thereof) to a downstream consumer of the product (e.g., as described above with respect to reactor output applications, as described in the appendices below, etc.). Optionally, the method may include modifying the reactor product after it has been produced (e.g., before providing the modified product to a downstream consumer). Optionally, modifying the reactor product may include modifying the product by purifying it (e.g., by converting it into SO x and / or NO xAlternatively, modifying the reactor product may include mixing additional gases (and / or other substances) into the reactor output stream (and / or input stream), for example, to achieve a desired output metric. In one variation, if the CO:H ratio of the reactor output differs from a desired value, the ratio may be adjusted by mixing the reactor output with other gases (e.g., substantially pure CO and / or H; another mixture of CO and H, such as the output of a previously produced and stored reactor, the output of a second reactor, the output of another system, and / or waste gases). For example, the CO:H ratio of the output stream (and / or gases in any other part of the reactor) may be monitored (e.g., continuously during reactor production), and deviations from the desired value may be compensated for by mixing with other gases (e.g., adding CO and / or a CO-rich mixture to increase the ratio, adding H and / or an H-rich mixture to decrease the ratio). Preferably, this example also includes modifying process conditions (e.g., as in closed-loop control, as described above) to correct the reactor output. In a second variation in which an external gas supply (e.g., output and / or waste gases of one or more other systems, such as a steel mill) is supplied to a downstream consumer (e.g., a gas fermentor), the reactor product is used to modify the CCP:H ratio (e.g., CO:H ratio) of the external gas supply (e.g., if the CCP:H ratio of the external gas supply differs from a desired value, the reactor product is mixed to achieve the desired value). For example, process conditions may be controlled to modify the CO:H ratio of the reactor product based on deviation of the external gas supply from the desired value (e.g., increasing the ratio in response to a CO-poor external gas supply, decreasing the ratio in response to a CO-rich external gas supply), and / or the amount of reactor product mixed with the external gas supply (e.g., to achieve the desired value) may be controlled. However, additionally or alternatively, the reactor output stream may be modified in any other suitable manner, or may be used without modification.

[0038] In some examples, the method may include determining one or more metrics (e.g., operational metrics) associated with one or more upstream and / or downstream elements of the system (e.g., downstream reactors, upstream inputs, etc.). Such operational metrics may include, for example, reactor conditions such as temperature, pressure, etc.; output metrics of downstream reactors and / or upstream sources such as output amount, composition, purity, etc.; metrics associated with other inputs for the downstream reactors such as input amount, composition, purity, etc.; reactor efficiency metrics; and / or any other suitable metrics. In such examples, the method preferably includes modifying the carbon dioxide reactor operation based on the metrics (e.g., to improve and / or maintain operation of downstream reactors; to improve and / or maintain operation of the carbon dioxide reactor, e.g., to accommodate changes in upstream sources; to improve and / or maintain a target output metric such as HCR or reduction product concentration, e.g., given a varying carbon dioxide source; etc.), such as by modifying the HCR of the carbon dioxide reactor output. However, additionally or alternatively, the method may include determining any other suitable metric and / or acting in any other suitable manner (eg, based on the metric). 4.Process Conditions

[0039] Process conditions may include input carbon dioxide flow rate and / or pressure, input gas hydration, current density, voltage (e.g., preferably maintained within a range of 1.5 V to 3 V, additionally or alternatively operated below 1.5 V, within a range of 2 V to 2.5 V, within a range of 2 V to 4 V, above 4 V, and / or any other suitable voltage), and / or temperature. Additionally or alternatively, process conditions may include system configurations such as gas diffusion layer aspects, catalyst aspects, flow field aspects, and / or PEM aspects. However, any other suitable process conditions may be controlled or targeted. Process conditions may be uncontrolled (e.g., dictated by an upstream system), controlled, or otherwise determined to meet target values ​​(e.g., target values ​​may be determined based on application, instantaneous, or expected reactor operating parameters receiving reactor output, or may be otherwise determined).

[0040] Preferably, the process conditions include pressures greater than atmospheric pressure (e.g., within and / or greater than a threshold pressure range, e.g., 1-5 atm, 5-10 atm, 10-20 atm, 20-50 atm, 50-100 atm, 100-300 atm, 300-1000 atm, 1-10 atm, 5-50 atm, 10-100 atm, 20-500 atm, and / or greater than 1000 atm, 14-50 psi, 50-150 psi, 100-300 psi, 200-500 psi). psi, 500-1000 psi, 750-1500 psi, 1000-3000 psi, 3000-10,000 psi, 10,000-20,000 psi, and / or greater than 20,000 psi), and / or pressures greater than those typically achievable in electrolytic cells other than gas-phase electrolytic cells (e.g., input gas pressure, reactor pressure, etc.), but may additionally or alternatively include pressures substantially equal to 1 atmosphere, pressures less than 1 atmosphere, and / or any other suitable pressure. Preferably, the process conditions include temperatures (e.g., reactor temperatures) higher than normal room temperature (e.g., within and / or above a threshold temperature range, such as 25-50°C, 40-60°C, 50-100°C, 50-75°C, 70-100°C, and / or above 100°C), and / or temperatures (e.g., reactor temperatures) higher than temperatures normally achievable in electrolytic cells other than gas-phase electrolytic cells, but may additionally or alternatively include temperatures substantially equal to room temperature (e.g., 20-30°C), below room temperature, and / or any other suitable temperature. However, additionally or alternatively, the process conditions may include any other suitable process conditions.

[0041] A higher carbon dioxide flow rate may result in increased production of CCPs such as CO (e.g., due to greater availability of carbon dioxide for reduction), i.e., an increased CCP:H ratio (correspondingly, a lower carbon dioxide flow rate may result in decreased CCP production and CCP:H ratio). In some embodiments, a higher carbon dioxide flow rate may also result in a decrease in carbon dioxide conversion efficiency, whereby the output stream (e.g., synthesis gas output) is diluted with unreacted carbon dioxide. For example, the carbon dioxide flow rate (e.g., measured at the reactor inlet) may be between 0.1 and 1000 sccm / cm 2 (e.g., 0.1 to 1 sccm / cm 2 , 1~10sccm / cm 2 , 10~100sccm / cm 2 , and / or 100 to 1000 sccm / cm 2 ) may be maintained at one or more values ​​within the range.

[0042] In a first example of control based on input gas flow rate, reactor configuration A with a triple serpentine flow field was used, reactor pressure was substantially maintained at 120 psi, and current density was 500 mA / cm. 2 and the reactor temperature is maintained substantially at 30° C. In this example, substantially pure carbon dioxide gas is input at various flow rates, ranging from 12 sccm / cm 2 , 20sccm / cm 2 , and 40sccm / cm 2 input flow rates (e.g., measured at the reactor inlet) result in CO:H2 ratios of about 1:1, 2:1.1, and 4:1, respectively.

[0043] In a second example of control based on input gas flow rate, reactor configuration A with a serpentine flow field was used, reactor pressure was maintained substantially at 130 psi, and current density was 500 mA / cm. 2 In this example, the concentration is substantially maintained at 40 sccm / cm 2 Substantially pure carbon dioxide gas input at a flow rate of 12 sccm / cm results in a CO:H ratio of about 8:2, while2 flow rate results in a ratio of approximately 1:1.

[0044] Higher carbon dioxide pressures may result in increased CCP fractional yields and / or CCP:H ratios (correspondingly, lower carbon dioxide pressures may result in decreased CCP fractional yields and / or CCP:H ratios). First, increasing carbon dioxide pressures may result in increased availability of carbon dioxide for reduction, thereby increasing total CCP production. Second, increasing pressure at the catalyst may reduce water ingress (e.g., from the cathode) into the catalyst, thereby reducing the amount of water available for reduction, which may directly increase the CCP:H ratio and / or reduce competition for catalyst reduction sites and / or reaction energy (e.g., thereby favoring carbon dioxide reduction). Thus, in some embodiments (e.g., where high CCP fractional yields and / or CCP:H ratios are desired), high reactor pressures (e.g., greater than 100 psi, up to the phase transition pressure of carbon dioxide, such as the critical pressure of 1070 psi or less) may be used. For example, the reactor pressure may be maintained at one or more values ​​within the range of 1 to 1100 psi (e.g., 1 to 10 psi, 10 to 100 psi, 100 to 300 psi, 200 to 600 psi, and / or 500 to 1100 psi), and / or any other suitable pressure.

[0045] In a specific example of reactor pressure-based control, reactor configuration A with a single serpentine flow field was used, with substantially pure carbon dioxide gas at 100 sccm / cm 2 and the current density was 150mA / cm 2 and the reactor temperature is maintained substantially at 20° C. In this example, the reactor pressure is maintained substantially at various pressures, with reactor pressures of 25, 50, 75, and 100 psi resulting in CO:H ratios of about 3:2, about 2.4:1, about 3:1, and about 5:1, and CO fractional yields of about 59%, about 69%, about 75%, and about 84%, respectively.

[0046] Increased hydration of the input gas can result in increased water reduction (e.g., due to increased availability of water for reduction), thereby resulting in a reduced CCP:H ratio. With a substantially pure carbon dioxide input, only a small amount of water reaches the catalyst (almost exclusively from the cathode side of the reactor), resulting in a larger CCP:H ratio. In contrast, when a hydrated input gas is used, a larger amount of water from the input gas can reach the catalyst and react. For example, the hydration of the input gas (e.g., percentage of water vapor in the input gas) can be maintained at one or more values ​​ranging 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).

[0047] In a specific example of input gas hydration-based control, reactor configuration A with a single serpentine flow field was used, and the current density was 50 mA / cm 2 The reactor pressure is substantially maintained at 12 psi, and the reactor temperature is substantially maintained at 20° C. In this example, carbon dioxide gas of various hydration amounts is supplied at 100 sccm / cm 2 A pure carbon dioxide input gas will result in a CO:H ratio of approximately 3:2, a 12.2% hydrated input gas will result in a CO:H ratio of approximately 1:5.67, and intermediate hydration amounts will result in CO:H ratios between these two values.

[0048] Reactors may exhibit different regimes of CCP and H production with respect to current density. In an ideal reactor, at low current densities, no water reduction occurs and all current goes toward carbon dioxide reduction, resulting in a substantially linear dependence of CO production on current and substantially no H production. In contrast, at higher current densities, additional current (e.g., above a threshold current at which substantially all carbon dioxide has already been consumed) is used to reduce water, resulting in a substantially linear dependence of H production on additional current and substantially constant CO production (e.g., as shown in FIG. 4A). In many typical reactors, these idealities are relaxed, but two general regimes are still exhibited: in the low current density regime, CO production increases much more rapidly than H production, and then reaches a plateau in the higher current density regime, while H production increases more rapidly (e.g., as shown in FIG. 4B). The method may include controlling CO and / or H production (e.g., controlling the CO:H ratio) by operating over any or all of a wide range of current densities (e.g., controlling reactor operation within a low current density regime and / or a high current density regime, etc.). In some embodiments, the use of gas-phase input carbon dioxide may allow for relatively high current densities (as opposed to reactors using aqueous carbon dioxide, which require tens of mA / cm). 2 For example, the method may be limited to a current density of 1 mA / cm 2 ~100Acm 2 Within the range (e.g., 1 to 75 mA / cm 2 , 50~100mA / cm 2 , 100~200mA / cm 2 , 200~500mA / cm 2 , 500~1000mA / cm 2 , 50~1000mA / cm 2 , 0.5~10A / cm 2 , 1~2A / cm 2 , 2~5A / cm 2 , 5~10A / cm 2 , 5~100A / cm 2 , 10~20A / cm2 , 20~50A / cm 2 , 50~100A / cm 2 etc;50mA / cm 2 , 65mA / cm 2 , 80mA / cm 2 , 90mA / cm 2 , 100mA / cm 2 , 110mA / cm 2 , 120mA / cm 2 , 130mA / cm 2 , 140mA / cm 2 , 150mA / cm 2 , 200mA / cm 2 , 300mA / cm 2 , 500mA / cm 2 , 700mA / cm 2 , 1000mA / cm 2 , 1500mA / cm 2 The method may include operating at a current density at, above, or below a threshold such as 0.1 V, 1 V, 2 V, 3 V, 4 V, 5 V, 6 V, 7 V, 8 V, 9 V, 10 V, 11 V, 12 V, 13 V, 14 V, 15 V, 16 V, 17 V, 18 V, 19 V, 20 V, 21 V, 22 V,

[0049] In some embodiments, increasing the reactor temperature may be achieved by increasing the CO:H 2 This may result in a reduction in the ratio (e.g., by increasing water intrusion from the cathode, by increasing water reactivity, etc.). The method may include controlling the reactor temperature within an operating range, such as a range between a minimum temperature (e.g., the freezing temperature of water such as 0°C) and a maximum temperature (e.g., 40°C, 50°C, 60°C, 75°C, etc.; the boiling temperature of water such as 100°C), to control the CO:H ratio and / or any other suitable output metric.

[0050] In a specific example of reactor temperature-based control, reactor configuration A with a quadruple serpentine flow field was used, with substantially pure carbon dioxide gas flowing at 70 sccm / cm 2 and the current density was 150mA / cm 2and the reactor pressure is maintained substantially at 100 psi. In this example, the reactor temperature is maintained substantially at various temperatures, with reactor temperatures of 26.7, 35, 38.7, and 41.9° C. resulting in CO:H ratios of about 1:0.4, 2:1, 1:1.8, and 1:3, respectively.

[0051] Additionally or alternatively, the properties of the gas diffusion layer (GDL) may be used to affect CCP and / or H production. For example, the hydrophobicity of the GDL may alter H production (e.g., by affecting water transport), while a more hydrophilic GDL favors H production (thereby decreasing the CCP:H ratio) and a more hydrophobic GDL inhibits H production (thereby increasing the CCP:H ratio). Other GDL properties, such as thickness and / or pore size, may be used to modify reactor output.

[0052] Additionally or alternatively, membrane (e.g., polymer electrolyte membrane) properties may be used to influence CCP and / or H2 production. In examples, high CCP:H2 ratios may be achieved using anion exchange membranes that favor CCP production, low CCP:H2 ratios may be achieved using cation exchange membranes that favor H2 production, and various intermediate ratios may be achieved using hybrid membranes (e.g., allowing transport of both anions and cations) that exhibit different anion and cation transport properties (e.g., mobilities) (e.g., membranes that favor a higher ratio of anion transport, membranes that favor a lower ratio of cation transport).

[0053] Additionally or alternatively, catalyst characteristics (e.g., particle size, catalyst species, etc.) may be used to influence CCP and / or H production. For example, larger catalyst particles may result in less carbon dioxide transport, thereby inhibiting CCP production and reducing the CCP:H ratio, whereas smaller catalyst particles may favor CCP production, thereby increasing that ratio. Additionally or alternatively, the total number of active sites with a high turnover frequency for hydrogen generation ("hydrogen sites") and the total number of active sites with a high turnover frequency for carbon dioxide reduction ("carbon dioxide sites") may depend on catalyst particle size. Larger catalyst particles typically have a larger ratio of hydrogen sites to carbon dioxide sites, favoring H production, whereas smaller catalyst particles typically have a smaller ratio, favoring CO production. Additionally or alternatively, catalyst types (e.g., catalytic species) may be used to control reactor output, for example, by using a mixture of one or more catalytic materials, where a first set of catalytic materials (e.g., gold) favors carbon dioxide reduction and a second set of catalytic materials (e.g., platinum) favors water reduction. In examples, a substantially pure gold catalyst may be used to achieve a high CCP:H ratio, a substantially pure platinum catalyst may be used to achieve a low CCP:H ratio, and mixtures of gold and platinum of variable composition (e.g., alloy particles, mixtures of gold 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 comprise 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. Additionally or alternatively, the catalyst may be associated with (e.g., bonded to, supported by, incorporated into, adjacent to, in contact with, etc.) one or more support structures (e.g., support particles, support substrates, etc.), preferably electrically conductive support structures such as carbon, boron-doped diamond, and / or fluorine-doped tin oxide.However, additionally or alternatively, the catalyst may comprise any other suitable material.

[0054] In a specific example of catalyst particle size-based control, a variation of reactor configuration A was used with two catalyst particle sizes, both of which were operated with a reactor temperature substantially maintained at 30°C, a reactor pressure substantially maintained at 100 psi, and an interconnected flow field, with substantially pure carbon dioxide gas at 10 sccm / cm. 2 and the current density was 500mA / cm 2 The first set of catalyst particles has a characteristic size of 4 nm (similar to 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.

[0055] Additionally or alternatively, reactor cell compression characteristics may be used to affect CCP and / or H2 production. In a specific example of reactor cell compression-based control, reactor configuration A was used with two different gasket thicknesses (larger gasket thickness resulting in higher pressure), both of which had a reactor temperature maintained substantially at 30°C, a reactor pressure maintained substantially at 100 psi, a triple serpentine flow field, and a flow of substantially pure carbon dioxide gas at 40 sccm / cm. 2 and the current density was 500mA / cm 2 The first gasket is 0.012 inches (0.3048 mm) thick and provides an HCR of 1:4 and a voltage of 3.6V. The second gasket is 0.010 inches (0.254 mm) thick and provides an HCR of 1:10.1 and a voltage of 3.8V.

[0056] Additionally or alternatively, flow field characteristics may be used to affect CCP and / or H2 production. In a first example of control based on flow field characteristics, reactor configuration A is used under two different sets of process conditions, both of which involve reactor temperature maintained substantially at 30°C and reactor pressure maintained substantially at 120 psi. In the first set of conditions, an interconnected flow field is used, and substantially pure carbon dioxide gas is supplied at 10 sccm / cm. 2 and the current density was 160mA / cm 2 In a second set of conditions, a quadruple serpentine flow field was used, with substantially pure carbon dioxide gas at 40 sccm / cm. 2 and the current density was 120mA / cm 2 This is maintained essentially at 18.5:1, resulting in a CO:H2 ratio of 18.5:1.

[0057] In a second example of control based on flow field characteristics, reactor configuration A was used under two different sets of process conditions, both of which involved a reactor temperature maintained substantially at 30° C., a reactor pressure maintained substantially at 100 psi, and a flow of substantially pure carbon dioxide gas at 40 sccm / cm. 2 and the current density was 500mA / cm 2 In a first set of conditions, an interconnected flow field was used and a voltage of 3.6 V was maintained substantially, resulting in a CO:H ratio of 1.6:1. In a second set of conditions, a triple serpentine flow field was used and a voltage of 3.8 V was maintained substantially, resulting in a CO:H ratio of 10.1:1.

[0058] However, any other suitable flow field may additionally or alternatively be used to control the reactor output, the process conditions may additionally or alternatively include any other suitable reactor conditions, and the method may additionally or alternatively include controlling the reactor output in any suitable manner. 5. Impurity resistance

[0059] In some embodiments, such as those in which the reactor is operated at high pressure and / or the catalyst is maintained at a low voltage (e.g., a negative voltage relative to the anode), the system and / or method may achieve a high tolerance to impurity and / or dilute carbon dioxide input, e.g., tolerance to poisoning by impurities in the reactor input and / or diluted input by species such as methane, CO, O, and / or N (e.g., compared to other carbon dioxide reactors). For example, the method may include determining target process conditions (e.g., reactor configuration such as PEM type, high target reactor pressure, etc.) to achieve tolerance to impurity and / or dilute input (e.g., always select such process conditions; select such process conditions depending on current and / or expected conditions of the reactor input, such as impure and / or dilute conditions; etc.). These impurities include SO, X and / or NO X The reactor input stream may include species typically present in the reactor input stream (e.g., products of coal combustion and / or natural gas combustion, such as the output from a coal-fired or natural gas-fired power plant), and / or may include any other suitable impurities. In one example, the system and / or method may include a maximum of 4% CO, 6% O, 10% O, 800 ppm NO, X and / or 100 ppm SO X and preferably has a total of 10% or less CO, O2 and N2 impurities.

[0060] In a specific example of dilute input tolerance, reactor configuration A with a single serpentine flow field was used, and the current density was 160 mA / cm 2 the reactor pressure is substantially maintained at 110 psi, the reactor temperature is substantially maintained at 20°C, and the carbon dioxide containing gas with various dilution levels in methane or nitrogen is fed at 200 sccm / cm 2In this example, reactor performance is highly tolerant to methane dilution up to at least 50% methane, with 0%, 25%, and 50% methane concentrations resulting in CO:H ratios ranging from 9.5:1 to 8.5:1 and CO fractional yields greater than 90%. An even greater reduction in performance is observed with 75% methane, with CO fractional yields reduced to approximately 84%. In this example, a similar tolerance is observed to nitrogen dilution, with 0%, 25%, 50%, and 75% nitrogen concentrations resulting in CO:H ratios ranging from 9:1 to 8:1 and up to 50% nitrogen concentrations resulting in CO fractional yields greater than 85% (75% nitrogen concentration resulting in CO fractional yields of approximately 81%).

[0061] In the impurity tolerance example, reactor configuration A with a single serpentine flow field was used, and the current density was 150 mA / cm 2 the reactor pressure is substantially maintained at 100 psi, the reactor temperature is substantially maintained within a range of 20°C to 25°C, and the carbon dioxide-containing gas having various impurities is supplied at 100 sccm / cm 2 In this example, reactor output metrics (e.g., CO fractional yield) under various impurity conditions are compared to baseline reactor performance under the same conditions, but with a carbon dioxide input that is substantially free of impurities. In this example, reactor performance is compared at CO concentrations of 4% or less, NO concentrations of 800 ppm or less, and CO concentrations of 100 ppm or less. X SO concentration of 120 ppm or less X It was shown that the ion exchange rate does not deviate significantly from the baseline performance at concentrations below 6% or below 6% oxygen.

[0062] However, additionally or alternatively, the system and / or method may exhibit any suitable tolerance to impure and / or diluted inputs, or may exhibit no such tolerance. 6. System configuration selection

[0063] Optionally, the method may include selecting one or more system configurations, preferably based on output HCR considerations, for example, based on a desired output HCR (e.g., given a particular set of process conditions and / or range of acceptable process conditions) and / or HCR range.

[0064] In some embodiments, this includes receiving an input comprising carbon dioxide in a first reactor (e.g., an electrolyzer, preferably a gas-phase electrolyzer) and electrochemically producing (e.g., under a first set of process conditions) a first reduction product (e.g., comprising molecular hydrogen at a first HCR and / or one or more CCPs other than carbon dioxide) from the input; 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 reactor) based on the first HCR and / or desired HCR (e.g., such that the second reactor outputs, or is capable of outputting, a reduction product having an HCR closer to the desired HCR for the first HCR; preferably substantially under the first set of process conditions, but additionally or alternatively, under any other suitable process conditions). For example, a configuration for the second reactor may be selected such that the second reactor produces a second reduction product from the input, preferably under conditions substantially matching those of the first reactor (e.g., while receiving the input under a first set of process conditions), the second reduction product comprising molecular hydrogen and the same CCS as the first reduction product (e.g., comprising substantially all species present in the first reduction product), and the second reduction product defines a second HCR that is substantially different from the first HCR, preferably the second HCR being 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 and second HCR may include the second HCR being closer to the desired HCR than the first HCR; differing 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 otherwise differing from the first HCR.

[0065] In some embodiments, selecting a system configuration may include selecting one or more aspects of the PEM, such as to alter the output HCR. Such selection may include selecting a membrane composition (e.g., different polymer species) and / or microstructure, selecting a membrane layer thickness, and / or selecting any other suitable aspect of the PEM. In some examples, such selection includes selecting anion exchange membrane and / or proton exchange membrane thickness (e.g., a bipolar PEM leaning toward AEM will tend to produce a lower output HCR than a bipolar PEM leaning toward proton exchange membrane). In a first specific example, selecting a thinner AEM (e.g., thinner than the thickness of a reference AEM, such as the thickness of the AEM of the first reactor, thinner than the thickness of an optimized AEM that substantially corresponds to optimal CCP production) may result in a reactor configured to produce a higher output HCR, whereas selecting a thicker AEM (e.g., thicker than the thickness of the reference AEM, but preferably not thicker than the thickness of the optimized AEM) may result in a reactor configured to produce a lower output HCR.

[0066] Additionally or alternatively, selecting a system configuration may include selecting one or more aspects of a reactor catalyst (e.g., reduction catalyst, oxidation catalyst), such as to vary the output HCR. In some variations, selecting an aspect of a reactor catalyst may include selecting a catalyst layer thickness (e.g., a thicker reduction catalyst will tend to produce a higher HCR). In one example, selecting a thicker reduction catalyst layer (e.g., thicker than a reference reduction catalyst layer thickness, such as a first reactor reduction catalyst layer thickness, thicker than an optimized reduction catalyst layer thickness substantially corresponding to optimal CCP generation) may result in a reactor configured to produce a higher output HCR, whereas selecting a thinner reduction catalyst layer (e.g., thinner than the reference reduction catalyst layer thickness, but preferably not thinner than the optimized reduction catalyst layer thickness) may result in a reactor configured to produce a lower output HCR.

[0067] Additionally or alternatively, selecting reactor catalyst aspects (e.g., in embodiments where the catalyst layer includes catalyst particles, preferably nanoparticles, that define a porous network) may include selecting a catalyst porosity (e.g., a more porous reduced catalyst network will tend to produce a lower HCR). In one example, selecting a less porous reduced catalyst network (e.g., less porous than a reference reduced catalyst, such as the porosity of the first reactor reduced catalyst network, less porous than an optimized reduced catalyst that substantially corresponds to optimal CCP production, etc.) may result in a reactor configured to produce a higher output HCR, whereas selecting a more porous reduced catalyst (e.g., more porous than the reference reduced catalyst, but preferably not more porous than the optimized reduced catalyst) may result in a reactor configured to produce a lower output HCR.

[0068] Additionally or alternatively, selecting the catalyst aspects of the reactor may include selecting a catalyst-to-polymer electrolyte ratio (CPR) (e.g., a higher reduction catalyst CPR will tend to result in a higher HCR) by, for example, selecting the grade of polymer electrolyte to load into the porous reduction catalyst network (e.g., in embodiments where the catalyst layer includes catalyst particles, preferably nanoparticles, and one or more polymer electrolytes, the catalyst particles define a porous network including the polymer electrolyte and / or are mixed with a medium including the polymer electrolyte). In one example, selecting a higher reduction catalyst CPR (e.g., a higher CPR than the reference reduction catalyst CPR, such as the CPR of the first reactor reduction catalyst network, a higher CPR than an optimized reduction catalyst substantially corresponding to optimal CCP production, etc.) may result in a reactor configured to produce a higher output HCR, whereas selecting a lower CPR reduction catalyst (e.g., a lower CPR than the reference reduction catalyst, but preferably not lower than the optimized reduction catalyst CPR) may result in a reactor configured to produce a lower output HCR.

[0069] Additionally or alternatively, selecting the reactor catalyst aspect (e.g., in embodiments in which the catalyst layer includes catalyst particles, preferably nanoparticles) may include selecting a characteristic catalyst particle size (e.g., larger particle sizes will tend to produce higher HCR). In one example, selecting a larger reduction catalyst particle size (e.g., larger than the particles of a reference reduction catalyst, such as a first reactor reduction catalyst, larger than an optimized reduction catalyst substantially corresponding to optimal CCP production, etc.) may result in a reactor configured to produce a higher output HCR, whereas selecting a smaller reduction catalyst particle size (e.g., smaller than the particles of the reference reduction catalyst, but preferably not smaller than the particles of the optimized reduction catalyst) may result in a reactor configured to produce a lower output HCR. However, additionally or alternatively, the method may include selecting any other suitable reactor catalyst aspect.

[0070] Additionally or alternatively, the method may include selecting a reactor cell compression (e.g., lower compression will tend to result in a higher HCR, and higher compression will tend to result in a lower HCR), a flow field, and / or any other suitable aspects of the system. 7. Appendix

[0071] The following provides additional information regarding optional embodiments and / or elements of the systems and / or methods.

[0072] The product gas from a carbon dioxide reactor of the invention may be used in one or more downstream processes. For example, a carbon dioxide reactor of the invention configured for syngas production may output a stream of CO, H, and / or CO. This output stream may be fed to the input of a bioreactor, where microorganisms (e.g., Clostridium autoethanogenum, Clostridium carboxydovorans, Clostridium ljungdahlii, Clostridium ragsdalei, Clostridium thermoaceticum, Clostridium thermoautotrophicum, Eubacterium limosum, Peptostreptococcus productus, Butyrivacterium methylotrophicum, Acetogens, Escherichia coli, etc.) use the energy of the CO, H, and / or a portion of the carbon contained in the CO and CO to create one or more bioproducts (e.g., ethanol, acetic acid, butanol, butyric acid, methane, etc.). Unused carbon may be released (e.g., as CO2, optionally along with water vapor and / or other volatile compounds) from the output of the downstream bioreactor.

[0073] Optionally, the released CO2 and the output of the downstream bioreactor may be recycled and reclaimed as input to the carbon dioxide reactor of the invention (e.g., to improve the carbon efficiency of bioproduct production, to control carbon dioxide reactor operation, etc.). In some embodiments, it may be desirable to treat this CO2 before it enters (e.g., reenters) the carbon dioxide reactor of the invention. For example, water vapor may be removed, any volatile products that would inhibit the function of the carbon dioxide reactor may be removed, and / or the CO2 may be pressurized to a level desired for operation of the carbon dioxide reactor of the invention. The carbon dioxide exiting the bioreactor may be near atmospheric pressure and / or have any other suitable pressure; typical carbon dioxide reactor pressures may be 20 psi to 800 psi, 50 psi to 400 psi, 100 psi to 500 psi, and / or any other suitable range. In some examples, water vapor is removed by a phase separator and / or a desiccant (e.g., a phase separator followed by a desiccant). In some examples, volatile products are removed by oxidation, by adsorption onto a suitable adsorbent, and / or by condensation. A CO compressor may be used to increase the pressure of the CO to a pressure suitable for the carbon dioxide reactor of the invention. If the carbon dioxide reactor can operate with low pressure CO and is not inhibited by water vapor or any volatile compounds detected in the CO stream output from the downstream bioreactor, the system can be simplified to eliminate unnecessary purification and compression systems and processes.

[0074] A flow rate of gas from the output of a carbon dioxide reactor of the invention per liter of medium in the downstream bioreactor may be desired in the range of 1 sccm to 1000 sccm, or 1 sccm to 2000 sccm, or 10 sccm to 500 sccm, or any other suitable range. Per liter of medium in the downstream bioreactor, the CO released may be in the range of 1 sccm to 2000 sccm, or 10 sccm to 1000 sccm, or 10 sccm to 500 sccm, or any other suitable range. For every liter of medium in the downstream bioreactor, water vapor in the output gas stream exiting the bioreactor may be 1% to 2% volume percent of the stream, 2% to 5% volume percent of the stream, 5% to 10% volume percent of the stream, 10% to 25% volume percent of the stream, 25% to 50% volume percent of the stream, 50% to 90% volume percent of the stream, and / or any other suitable amount. Volatile products exiting the downstream bioreactor may constitute less than 0.1% volume percent of the stream, less than 0.5%, less than 1% volume percent of the stream, less than 4% volume percent of the stream, and / or any other suitable amount of the stream.

[0075] Some microbial processes may use the syngas produced by the carbon dioxide reactor of the present invention. The syngas output stream of CO, H, and CO may be used as a feedstock for a downstream bioreactor, where microbial processes are carried out to create a range of useful compounds (examples include ethanol, acetic acid, butanol, butyric acid, and methane). The syngas stream itself may not contain all the nutrients necessary for the growth of the microorganisms in the downstream bioreactor. The addition of other nutrients to the bioreactor may be required for the microorganisms to grow and produce products. Examples of suitable microorganisms include Clostridium autoethanogenum, Clostridium carboxydovorans, Clostridium ljungdahlii, Clostridium ragsdalei, Clostridium thermoaceticum, Clostridium thermoautotrophicum, Eubacterium limosum, Peptostreptococcus productus, Butyrivacterium methylotrophicum, acetogens, and / or Escherichia coli.

[0076] One nutrient that can be particularly difficult to introduce into a downstream bioreactor is sulfur. Many microorganisms require sulfur for certain amino acid synthesis and enzymatic processes. The sulfur-tolerant carbon dioxide reactor of the present invention may simplify the addition of sulfur to the downstream bioreactor (e.g., by adding it to the syngas provided to the downstream bioreactor). H2S, SO2, and / or other sulfur oxides (SO2) X Sulfur in the form of one or more sulfur-containing species (SCS), such as H2S, may be present in the CO2 gas supplied to the input of the carbon dioxide reactor of the present invention. H2S may pass through the carbon dioxide reactor of the present invention unchanged and exit with the synthesis gas output stream. SCS (e.g., SO2 and / or SO2) may be present in the CO2 gas supplied to the input of the carbon dioxide reactor of the present invention. H2S may pass through the carbon dioxide reactor of the present invention unchanged and exit with the synthesis gas output stream. x ) may be passed through unchanged and / or the SCS may be converted to one or more other SCS (e.g., H2S), preferably output with the syngas output stream. This is followed by further conversion of sulfur species (e.g., H2S, SO2 and / or SO2) to SCS. x) may be fed to the input of a downstream bioreactor (e.g., no additional sulfur nutrient is needed). The concentration of sulfur species may be in the range of 1 ppm to 10 ppm, 5 ppm to 50 ppm, 5 ppm to 100 ppm, 10 ppm to 200 ppm, 20 ppm to 1000 ppm, and / or any other suitable range.

[0077] In some embodiments, the carbon dioxide reactor may be coupled to one or more gas fermentation reactors (e.g., downstream of the carbon dioxide reactor, e.g., receiving one or more products of the carbon dioxide reactor). Optionally, the method may include controlling reactor operation based on this coupling, such as to optimize carbon and / or energy efficiency. As shown in the energy balances shown in Table 1, acetogens with pure CO as input are the most energy efficient and, in many cases, also exhibit the highest selectivity to desired end products. However, there are cases where an integrated electrochemical gas fermentation system can be designed to use hydrogen-containing syngas for several reasons. [Table 1]

[0078] Typically, using CO for most or all of the electron transfer chemistry in the downstream bioreactor results in the production of CO, which may then be vented into the output stream of the bioreactor. Typically, as the proportion of hydrogen in the syngas increases, less CO is produced, and the CO by-product may be removed stoichiometrically above a certain ratio of hydrogen to carbon monoxide. For example, in the case of gas fermentation to ethanol, a CO:H ratio of less than 1:2 will typically result in the incorporation of all input carbon into the ethanol end product. Thus, adjusting the CO:H ratio in the output stream of a carbon dioxide reactor of the invention may allow an operator to optimize carbon efficiency (e.g., to minimize CO emissions) by shifting toward more H production and / or optimize energy efficiency by shifting toward higher CO production. Monitoring input costs, such as time-of-day electricity rates or incentives for carbon utilization, could inform optimal operating parameters at any given time. Adjusting production in this manner may also change output, for example, by driving toward more ethanol production (e.g., higher CO) or more acetate production (e.g., higher H). Monitoring the market price of output could inform optimal operating parameters at any particular time (e.g., operating parameters determined based on market prices to optimize market price of a product, or to optimize total profit from reactor operation, etc.).

[0079] However, additionally or alternatively, the system and / or method may include any other suitable elements.

[0080] Preferably, alternative embodiments implement some or all of the above methods in a computer-readable medium having computer-readable instructions stored thereon. The instructions are preferably executed by computer-executable components, preferably integrated with a communications routing system. The communications routing system may include a communications system, a routing system, and a pricing system. The computer-readable medium may be stored in any suitable computer-readable medium, such as RAM, ROM, flash memory, EEPROM, an optical device (CD or DVD), a hard drive, a floppy drive, or any suitable device. The computer-executable component is preferably a processor, although alternatively or additionally, the instructions may be executed by any suitable dedicated hardware device.

[0081] Although omitted for simplicity, system and / or method embodiments may include any combination and permutation of the various system components and various method processes, and one or more examples of the methods and / or processes described herein may be performed asynchronously (e.g., sequentially), concurrently (e.g., in parallel), or in any other suitable order by and / or using one or more example systems, elements, and / or entities described herein.

[0082] The drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to preferred embodiments, exemplary configurations, and variations thereof. In this regard, each block in a flowchart or block diagram may represent a module, segment, step, or portion of code, which includes one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions depicted in the block diagrams may occur out of the order depicted in the figures. For example, two blocks shown in succession may in fact be executed substantially in parallel, or the blocks may be executed in reverse order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a dedicated hardware-based system that performs the specified function or operation, or by a combination of dedicated hardware and computer instructions.

[0083] As those skilled in the art will appreciate from the above detailed description, and from the drawings and claims, modifications and variations can be made to the preferred embodiments of the invention without departing from the scope of the invention as defined in the following claims. The following items are also disclosed: [Item 1] 1. A method for electrolytic cell control comprising: receiving an input comprising gas phase carbon dioxide at a first gas phase electrolyzer; receiving the input in the first gas-phase electrolyzer while electrochemically producing a first reduction product from the input under set process conditions; the first reduction product comprises molecular hydrogen and carbon-containing species (CCS), wherein the CCS is not carbon dioxide; and the first reduction product defines a first molecular hydrogen to CCS ratio (HCR); selecting a configuration for a second gas phase electrolyzer based on a desired HCR such that the second gas phase electrolyzer produces a second reduction product from the input while receiving the input under the set of process conditions; the second reduction product comprises molecular hydrogen and the CCS; and the second reduction product defines a second HCR that is substantially different from the first HCR. [Item 2] the first gas-phase electrolytic cell has a first cathode, a first anode, and a first polymer electrolyte membrane (PEM) comprising a polymer electrolyte species, the first PEM being disposed between the first cathode and the first anode; the second gas phase electrolytic cell comprises a second cathode, a second anode, and a second PEM containing the polymer electrolyte species, the second PEM being disposed between the second cathode and the second anode; 2. The method of claim 1, wherein selecting the configuration comprises selecting the second PEM based on the desired HCR. [Item 3] the first PEM has a first anion exchange membrane (AEM) defining a first layer thickness; selecting the second PEM includes selecting a second AEM that defines a second layer thickness that is substantially less than the first layer thickness; 3. The method of claim 2, wherein the second HCR is substantially greater than the first HCR. [Item 4] the first gas-phase electrolyzer has a first cathode, a first anode, a first polymer electrolyte membrane (PEM) containing a polymer electrolyte species, and a first reduction catalyst layer; the first PEM is disposed between the first cathode and the first anode; the first reduction catalyst layer is disposed between the first cathode and the first PEM; the second gas phase electrolyzer has a second cathode, a second anode, a second PEM containing the polymer electrolyte species, and a second reduction catalyst layer; the second PEM is disposed between the second cathode and the second anode; the second reduction catalyst layer is disposed between the second cathode and the second PEM; 4. The method according to any one of items 1 to 3, wherein the step of selecting a configuration includes a step of selecting the second reduction catalyst layer based on the desired HCR. [Item 5] The first reduction catalyst layer comprises: a first porous network composed of catalyst nanoparticles; the polymer electrolyte species disposed within the first porous network; The second reduction catalyst layer comprises: a second porous network composed of catalyst nanoparticles; the polymer electrolyte species disposed within the second porous network. [Item 6] the first reduction catalyst layer defines a first polymer electrolyte to catalyst nanoparticle ratio (ECR); selecting the second reduction catalyst layer includes selecting a second ECR that is substantially greater than the first ECR; 6. The method of claim 5, wherein the second HCR is substantially greater than the first HCR. [Item 7] the first porous network defines a first porosity; selecting the second reduction catalyst layer includes selecting a second porosity that is substantially less than the first porosity; 6. The method of claim 5, wherein the second HCR is substantially greater than the first HCR. [Item 8] the first porous network defines a first characteristic nanoparticle size; selecting the second reduction catalyst layer includes selecting a second characteristic nanoparticle size that is substantially larger than the first characteristic nanoparticle size; 6. The method of claim 5, wherein the second HCR is substantially greater than the first HCR. [Item 9] 9. The method of claim 8, wherein the first characteristic nanoparticle size and the second characteristic nanoparticle size are median sizes. [Item 10] the first reduction catalyst layer defines a first layer thickness; selecting the second reduction catalyst layer includes selecting a second layer thickness that is substantially greater than the first layer thickness; 5. The method of claim 4, wherein the second HCR is substantially greater than the first HCR. [Item 11] configuring the second gas phase electrolyzer in said configuration in response to selecting said configuration; receiving, after the step of configuring the second gas phase electrolyzer, a second input at the second gas phase electrolyzer comprising gas phase carbon dioxide; receiving the second input in the second gas phase electrolyzer while electrochemically producing a third reduction product from the input under a second set of process conditions; the third reduction product comprises molecular hydrogen and the CCS; the third reduction product defines a third HCR, and a first difference between the first HCR and the desired HCR is greater than a second difference between the third HCR and the desired HCR. [Item 12] the second input is substantially equal to the input; the second set of process conditions is substantially equal to the first set of process conditions; Item 12. The method of item 11, wherein the third HCR is substantially equal to the second HCR. [Item 13] the input defines a first humidity; the second input defines a second humidity that is substantially greater than the first humidity; the desired HCR is greater than the first HCR; Item 12. The method of item 11, further comprising selecting the second humidity based on the desired HCR. [Item 14] 14. The method of any one of items 1 to 13, wherein the CCS is carbon monoxide. [Item 15] 15. The method according to any one of items 1 to 14, wherein the set of process conditions comprises an electrolytic cell temperature greater than 50°C and an input pressure greater than 10 atmospheres. [Item 16] 1. A method for electrolyzer control, comprising: electrochemically producing reduction products comprising molecular hydrogen and carbon-containing species (CCS) from an input comprising gas phase carbon dioxide in a gas phase electrolyzer, wherein the CCS is not carbon dioxide; The step of electrochemically generating a reduction product comprises: producing the reduction products at a first molecular hydrogen to CCS ratio (HCR) during a first time interval, wherein producing the reduction products comprises operating the gas phase electrolyzer under a first set of process conditions; and adjusting operation of the electrolytic cell to vary the HCR of the reduction product during a second time interval after the first time interval, said adjusting comprising operating the gas phase electrolytic cell under a second set of process conditions to produce the reduction product at a second HCR that is substantially different from the first HCR. [Item 17] During the first time interval, the input defines a first humidity; adjusting operation of the electrolytic cell includes varying the humidity of the input such that the input defines a second humidity that is substantially greater than the first humidity during the second time interval; Item 17. The method of item 16, wherein the second HCR is greater than the first HCR. [Item 18] 18. The method of claim 16 or 17, wherein adjusting operation of the electrolytic cell to alter the HCR of the reduction product is performed in response to determining a desired HCR that is substantially different from the first HCR. [Item 19] providing the reduction product to a downstream reactor; determining operational metrics associated with the downstream reactor; 20. The method of claim 18, wherein determining the desired HCR is performed based on the operational metrics. [Item 20] the downstream reactor is a bioreactor; the input further comprises sulfur-containing species (SCS), the concentration of the SCS in the input being at least 5 ppm; 20. The method of claim 19, further comprising providing the SCS mixed with the reduction product to the bioreactor. [Item 21] the first set of process conditions comprising a first electrolytic cell temperature greater than 50°C and a first input pressure greater than 10 atmospheres; 21. The method of any one of items 16 to 20, wherein the second set of process conditions comprises a second electrolytic cell temperature greater than 50°C and a second input pressure greater than 10 atmospheres.

Claims

1. 1. A method for electrolytic cell control comprising: receiving a first input comprising gas phase carbon dioxide in a gas phase electrolyzer comprising a cathode layer comprising an ionically conductive polymer in contact with a reduction catalyst and a polymer electrolyte membrane; receiving the first input in the gas phase electrolyzer under a first set of process conditions while electrochemically producing a first reduction product stream from the first input; the first reduction product stream comprises molecular hydrogen and carbon monoxide; the first reduction product stream defines a first molecular hydrogen to carbon monoxide ratio (first HCR); monitoring the first HCR during operation of the gas phase electrolyser; adding molecular hydrogen to the first reduction product stream to produce a second product stream having a desired second HCR; directing the second product stream to a downstream system comprising a Fischer-Tropsch reactor; The method, wherein the first HCR is less than 1:

1.

2. 10. The method of claim 1, further comprising producing molecular hydrogen from a second electrolyzer, said molecular hydrogen being added to said first reduction product stream to obtain said desired second HCR.

3. 3. The method of claim 1 or 2, wherein the desired second HCR is in the range of 1:5 to 3:

1.

4. 3. The method of claim 1 or 2, wherein the desired second HCR is 2:1 or greater.

5. The method of claim 1, wherein the first HCR is less than 1:

5.

6. 5. The method of claim 1, wherein the first HCR is between 1:5 and 1:18.

5.

7. The method of claim 1 , wherein the downstream system comprises a purification system.

8. The method of claim 1 , wherein the downstream system comprises a gas compression system.

9. 9. The method of claim 1, further comprising compressing the second product stream prior to introduction into the Fischer-Tropsch reactor.

10. 10. The method of claim 1, further comprising purifying the second product stream prior to introduction into the Fischer-Tropsch reactor.

11. The method of claim 1, wherein the flow rate of the gas phase carbon dioxide of the first input is greater than 1 sccm / cm 2 .

12. A method described in any one of claims 1 to 11, wherein the pressure of the gas phase carbon dioxide of the first input is at least 50 psi.

13. The method of claim 1, further comprising an external gas supply means for supplying the hydrogen molecules for addition to the first reduction product stream.

14. 1. A system for producing liquid hydrocarbons from carbon dioxide, comprising: (a) a carbon dioxide reduction electrolyzer configured to include a cathode layer comprising an ionically conductive polymer in contact with a reduction catalyst and a polymer electrolyte membrane to facilitate the chemical reduction of said carbon dioxide to carbon monoxide, and to output said carbon monoxide and hydrogen; and (b) a Fischer-Tropsch reactor configured to transport the carbon monoxide and the hydrogen from the carbon dioxide reduction electrolyzer and additional molecular hydrogen to produce a mixture of liquid hydrocarbons; Equipped with the ratio of hydrogen molecules to carbon monoxide of the output hydrogen and carbon monoxide is less than 1:1; system.

15. The system of claim 14, wherein the ratio of hydrogen molecules to carbon monoxide of the hydrogen, the added hydrogen molecules and the carbon monoxide transported to the Fischer-Tropsch reactor is within the range of 1:5 to 3:

1.

16. The system of claim 14, wherein the ratio of hydrogen molecules to carbon monoxide of the hydrogen, the added hydrogen molecules and the carbon monoxide transported to the Fischer-Tropsch reactor is 2:1 or greater.

17. A system as claimed in any one of claims 14 to 16, wherein the ratio of hydrogen molecules to carbon monoxide of the output hydrogen and carbon monoxide is less than 1:

5.

18. A system described in any one of claims 14 to 17, wherein the ratio of hydrogen molecules to carbon monoxide of the output hydrogen and carbon monoxide is between 1:5 and 1:18.

5.

19. 19. The system of any one of claims 14 to 18, further comprising a gas compression system for compressing an output stream of the carbon dioxide reduction electrolyzer.

20. 20. The system of any one of claims 14 to 19, further comprising a purification system for purifying an output stream of the carbon dioxide reduction electrolyzer.

21. The system of claim 14, wherein the flow rate of the carbon dioxide input to the carbon dioxide reduction electrolyzer is greater than 1 sccm / cm 2 .

22. A system described in any one of claims 14 to 21, wherein the pressure of the carbon dioxide input to the carbon dioxide reduction electrolytic cell is at least 50 psi.

23. The system of claim 14, further comprising an external gas supply means for supplying the added hydrogen molecules.

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