Devices, systems and methods for improving co2 utilization in processes for converting co 2 to fuels and useful products

Abstract

A CO2 electrolyzer, incorporating an in-situ carbon capture layer, reducing CO2 crossover, thereby enhancing CO2 conversion efficiency. In some embodiments, the device features an in-situ carbon capture layer composed of a carbon regeneration layer and a barrier layer. In some embodiments, within this structure, CO2 is captured and subsequently recycled to the cathode for CO production.

Description

DEVICES, SYSTEMS AND METHODSFOR IMPROVING CO2UTILIZATION IN PROCESSES FOR CONVERTING CO2TO FUELS AND USEFUL PRODUCTSStatement of Government Interest

[0001] The inventions were made, at least in part, with U.S. government support under Subcontract SUB-2022-10244 under U.S. Department of Energy Grant No. DE-AC36-08GO28308. The government has certain rights in the inventions.Cross-Reference to Related Application(s)

[0002] The present application is related to and claims priority benefits from U.S. Provisional Patent Application Serial No. 63 / 568,156 filed on March 21, 2024, entitled “Devices, Systems And Methods For Improving CO2 Utilization In Processes For Converting CO2 To Fuels And Useful Products”. The 63 / 568,156 application is hereby incorporated herein its entirety.Field of the Invention

[0003] The field of the inventions is electrochemistry. The devices, systems, and methods described involve the process for the electrochemical reduction of CO2 to carbon monoxide (CO) that shows low CO2 crossover.Background of the Invention

[0004] Recycling generated carbon dioxide back to fuels and useful chemicals is beginning to make a difference to the U.S. economy. Presently, fuels and organic chemicals are still usually made from petroleum, coal, and / or natural gas “fossil fuels”. However, increasing the amount of such fuels and chemicals that are made from recycled CO2, will reduce the U.S. dependence on imported oil. Furthermore, emissions of greenhouse gases that contribute to climate change would also be reduced as CO2 produced in power plants would change from a waste product to a useful, economically viable feedstock.

[0005] The United States has made the deployment of systems and facilities to generate renewable fuels a major priority. The economics associated with the production of renewable fuel are also favorable. The US Department of Energy has created a $10,000,000 per year consortium “Reduction and Upgrading for e- Fuels (CCERue)” whose objective is to develop the technology to convert waste CO2 from an ethanol biorefinery into sustainable aviation fuel (SAF).

[0006] The field of CO2 conversion to valuable products has seen rapid advancements in recent years, driven by the urgent need to address climate change and develop sustainable energy sources. Researchers have explored various approaches, including electrochemical, thermochemical, and biological methods, to efficiently convert CO2 into fuels and chemicals.

[0007] Electrochemical CO2 reduction, in particular, has garnered significant attention due to its potential for high selectivity and compatibility with renewable electricity sources. This approach typically involves the use of a cathode, where CO2 is reduced to form products such as carbon monoxide, formic acid, ethylene, or alcohols, and an anode, where water is oxidized to produce oxygen and protons. The choice of catalyst materials, electrolyte composition, and operatingconditions play crucial roles in determining the product distribution and overall efficiency of the process.

[0008] Numerous patents have been issued over the years including U.S. Patent No. 10,774,431, U.S. Patent No. 9,849,450; U.S. Patent No. 9,580,824; U.S. Patent No. 9,370,773; U.S. Patent No. 9,181,625, U.S. Patent No. 9,9566,574, and U.S. Patent No. 9,012,345.

[0009] In addition, many applications have published including US20130015064A1, US20110237830, W02011120021A1, W02012006240A1, WO2012177952A2, W02016064440A1 and WO2016064447 Al.

[0010] The entire contents of U.S. Patent Nos. 10,774,431; 9,849,450; 9,580,824; 9,370,773; 9,181,625; 9,566,574; and 9,012,345, as well as U.S. Patent Application Publication Nos. US20130015064A1 and US20110237830, and International Patent Application Publication Nos. W02011120021A1, W02012006240A1, WO2012177952A2, W02016064440A1, andWO20 16064447 Al are hereby incorporated by reference in their entirety. The devices, systems, and methods disclosed in the present application may include any of the features, components, or steps described in these incorporated references, either individually or in combination with other aspects of the present disclosure.

[0011] While significant progress has been made in the field of CO2 conversion and utilization, several challenges remain unaddressed by existing technologies. Many current approaches struggle to achieve high carbon conversion efficiency, often limited to around 50% conversion of carbon input to desired products like sustainable aviation fuel (SAF). This inefficiency results in substantial carbon loss and reduces the overall environmental and economic benefits of these processes. If one converted all of the waste CO2 produced at justa few biorefineries, one could produce billions of gallons of SAF.

[0012] Furthermore, existing systems frequently encounter issues with CO2 crossover in electrochemical cells. This phenomenon, where CO2 migrates through membranes or other cell components, leads to reduced product yield and decreased overall system efficiency. The inability to effectively capture and recycle this crossed-over CO2 represents a significant limitation in current technologies.

[0013] Another shortcoming in the prior art is the lack of effective in-situ carbon capture mechanisms within electrochemical CO2 conversion systems. Many existing designs do not incorporate features to immediately capture and reuse CO2 that can escape the primary reaction zone, leading to unnecessary losses and reduced overall carbon utilization.

[0014] Additionally, the scalability of current CO2 conversion technologies remains a challenge. While many systems demonstrate promising results at laboratory scales, they often face difficulties in maintaining efficiency and selectivity when scaled up to industrially relevant sizes. This limitation hinders the widespread adoption and commercial viability of CO2 conversion technologies.

[0015] The integration of CO2 conversion processes with existing industrial infrastructure, particularly in sectors like biofuel production, also presents challenges that have not been fully addressed. Many current approaches require significant modifications to existing systems or are not easily adaptable to different types of CO2 sources, limiting their practical implementation.

[0016] Lastly, the energy efficiency of CO2 conversion processes remains a concern. Many existing methods require high energy inputs, which can offset the environmental benefits of CO2 utilization if the energy source is not renewable. Improving the energy efficiency of these processes, particularly in the context of electrochemical CO2 reduction, is a critical area that requires further development.Summary of the Invention

[0017] An electrolyzer for converting CO2 to useful products, particularly CO is disclosed. In some embodiments, the electrolyzer comprises multiple layers arranged in a specific configuration to enhance CO2 conversion efficiency and minimize, or at least reduce, CO2 crossover.

[0018] In some embodiments, the electrolyzer includes an anode flow field and a cathode flow field, which can be designed as serpentine, parallel, interdigitated, spiral, or fractal flow fields to improve reactant distribution and product removal. These flow fields can be made from conductive materials such as graphite or metal.

[0019] In some embodiments, an anode is present, which can comprise IrC>2 nanoparticles catalyst painted or otherwise deposited on a first gas diffusion layer. In some embodiments, the catalyst facilitates the oxygen evolution reaction at the anode.

[0020] In some embodiments, the electrolyzer includes a barrier layer and a regeneration layer, which together can form an in-situ carbon capture system. In some embodiments, the barrier layer can comprise a cation exchange membrane,which helps prevent, or at least reduce, anion crossover. In some embodiments, the regeneration layer comprises an ion exchange media, which can include cation exchange resin beads, anion exchange resin beads, sulfonated PPS fiber felt, or an acidic hydrogel. In some embodiments, the regeneration layer can have a thickness of no more than 2 mm to maintain low cell resistance. In some embodiments, the regeneration layer can have a thickness of no more than 1mm thick. In some embodiments, the regeneration layer can have a thickness of no more than 0.5mm.

[0021] In some embodiments, the electrolyzer incorporates either an anion exchange membrane or an ionomer coated porous layer. In some embodiments, the anion exchange membrane can be a self-standing membrane, a reinforced membrane, or a porous anion exchange membrane. In some embodiments, the anion exchange membrane can comprise a benzyl group bonded to various functional groups such as imidazolium, pyridinium, pyrazolium, pyrrolidinium, pyrrolium, pyrimidium, piperidinium, indolium, triazinium, phosphonium, or a quaternary amine.

[0022] In some embodiments, the electrolyzer incorporates a cathode. In some embodiments, the cathode can comprise Ag nanoparticles as catalyst layer painted or supported on a second gas diffusion layer. In some embodiments, the catalyst layer can also include a thin layer of anion exchange ionomer with a thickness ranging from 5-100 pm, more preferably 10-80 pm, or even more preferably 20-50 pm.

[0023] In some embodiments, the electrolyzer achieves significant reduction in CO2 crossover to the anode. In various embodiments, the CO2 crossover is less than 20%, 10%, 5%, or even 1%, demonstrating the effectiveness of the in-situ carbon capture system.

[0024] In some embodiments, the electrolyzer can include a cation exchange membrane, which can be a self-standing and reinforced membrane, providing additional stability and separation between the anode and cathode compartments.

[0025] In some embodiments, the multi-layered design allows for efficient CO2 conversion while minimizing, or at least reducing, losses due to crossover, leading to higher overall carbon utilization in the production of valuable products such as CO.

[0026] In some embodiments, CO2 is captured and subsequently recycled to the cathode for CO production. In some embodiments, the barrier layer is cationconducting polymer electrolyte membrane.

[0027] In some embodiments, a porous anion exchange membrane is prepared by dipping a porous support into an ionomer solution multiple times until a desired loading is reached.

[0028] In some embodiments, the porous anion exchange membrane is prepared by applying a first polymer solution onto a PET liner to create an applied first polymer solution layer; subsequently placing a porous support onto the applied first polymer solution layer; and applying at least one additional polymer solution to achieve a desired membrane property.

[0029] In some embodiments, the cathode catalyst layer comprises Ag nanoparticles or Ag alloy nanoparticles painted on a second gas diffusion layer.Brief Description of the Drawings

[0030] FIG. 1 is a schematic diagram of a process to convert CO2 from a point source, such as a biorefinery, into a product, such as SAF

[0031] FIG. 2 is a graph showing the effect of the rate of CO2 crossover on the fraction of the CO2 that is incorporated into an ethanol product.

[0032] FIG. 3 is a schematic diagram of an embodiment of an electrolyzer.

[0033] FIG. 4 is a schematic diagram of another embodiment of an electrolyzer.Detailed Description of Illustrative Embodiments

[0034] It is understood that the process is not limited to the particular methodology, protocols and reagents described herein, as these can vary as persons familiar with the technology involved here will recognize. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the process. It also is to be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to “a linker” is a reference to one or more linkers and equivalents thereof known to those skilled in the art. Similarly, the phrase “and / or” is used to indicate one or both stated cases can occur, for example, A and / or B includes (A and B) and (A or B).

[0035] Unless defined otherwise, technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the process pertains. The embodiments of the process and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and / or detailed in the following description. It should be noted that features of one embodiment can be employed with other embodiments as the skilled artisan would recognize, even if not explicitly statedherein.

[0036] Any numerical value ranges recited herein include all values from the lower value to the upper value in increments of one unit, provided that there is a separation of at least two units between any lower value and any higher value. As an example, if it is stated that the concentration of a component or value of a process variable such as, for example, size, angle size, pressure, time and the like, is, for example, from 1 to 98, specifically from 20 to 80, more specifically from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32, and the like, are expressly enumerated in this specification. For values which are less than one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value are to be treated in a similar manner.

[0037] Moreover, provided immediately below is a “Definitions” section, where certain terms related to the process are defined specifically. Particular methods, devices, and materials are described, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the process.Definitions

[0038] The term “polymer electrolyte membrane” as used here refers to both cation exchange membranes, which generally comprise polymers having multiple covalently attached negatively charged groups, and anion exchange membranes, which generally comprise polymers having multiple covalently attached positively charged groups.

[0039] Typical cation exchange membranes include proton conducting membranes, such as the perfluorosulfonic acid polymer available under the tradedesignation NAFION® from E. I. du Pont de Nemours and Company (DuPont) of Wilmington, DE.

[0040] Typical anion exchange membranes include but not limited to Sustainion® (Dioxide Materials), PiperlON® (Versogen), Aemion+® (lonomr).

[0041] The term “anion exchange membrane electrolyzer” or “AEM electrolyzer” as used here refers to an electrolyzer with an anion-conducting polymer electrolyte membrane separating the anode from the cathode.

[0042] The term “MEA” as used here refers to a membrane electrode assembly.Specific Description

[0043] Processes utilizing electrochemical cells for chemical conversions have been known for years. Generally, an electrochemical cell contains an anode, a cathode and an electrolyte. Catalysts can be placed on the anode, the cathode, and / or in the electrolyte to promote the desired chemical reactions. During operation, reactants or a solution containing reactants are fed into the cell. Voltage is then applied between the anode and the cathode, to promote the desired electrochemical reaction.

[0044] When an electrochemical cell is used as a CO2 conversion system, a reactant comprising CO2, carbonate or bicarbonate is fed into the cathode of the cell. A voltage is applied to the cell, and the CO2 reacts to form new chemical compounds.

[0045] FIG. 1 shows conversion system 1000 for converting CO2 into aviation fuels. The back end of the conversion system 1000 involves gas fermentation and ethanol conversion to SAF, while the font end of the system involves electrolyzer 150.

[0046] Current technologies only convert about 50% of CO2 in stream SI into SAF, using CO stream S3 and ethanol stream S8 as intermediates. Presently, about a third of the CO2 fed into electrolyzers is not converted into products. Instead, the CO2 crosses through the membrane and leaves through the oxygen stream S4. Some of this carbon can be recaptured as stream S5, but a fraction of the CO2 is lost (i.e., emitted with oxygen stream S10.) In practice, it is hard to get over 60% carbon conversion to ethanol with an economic recapture system. In some embodiments, CO2 from stream S6 from gas fermenter can also be recaptured. In some embodiments, CO2 stream S5 and CO2 stream S6 are combined to form recaptured CO2 stream S7, which is subsequently merged with stream SI to generate stream S2.

[0047] One way to improve the yield of SAF is to eliminate, or at least reduce, the amount of CO2 lost in electrolyzer 150. Generally, CO2 enters the system in stream SI and leaves in stream S9, and stream S10. In some embodiments, by using a barrier layer to at least reduce, if not prevent, CO2 crossover at stream S4, the fraction of the CO2 feed converted to product is increased.

[0048] In some embodiments, conversion system 1000 is powered by power source 180. In some embodiments, power source 180 is a source of renewable energy such as a solar panel or wind turbine. Use of renewable resources to power conversion system 1000 aligns the system’s goal of creating a sustainable process for converting waste CO2 into valuable products, potentially allowing for carbon- neutral or even carbon-negative fuel production when considering the full lifecycle of the process.

[0049] FIG. 2 illustrates the effect of the rate of CO2 crossover on the fraction of the CO2 that is incorporated into ethanol. The calculation assumes 70% recapture. Notice that, in principle, one could reach 95% CO2 utilization byeliminating the CO2 crossover entirely.

[0050] FIG. 3 illustrates an embodiment of electrolyzer 4000 configured to convert CO2 to CO. In some embodiments, such as shown in FIG. 3, electrolyzer 4000 includes cathode flow field 410, cathode 490 comprising a cathode gas diffusion layer 420 and cathode catalyst layer 430, anion exchange membrane 440, anode 495 comprising anode catalyst layer 450 and anode gas diffusion layer 460, and anode flow field 470.

[0051] In some embodiments, cathode flow field 410 is a serpentine flow field. In some embodiments, anode flow field 470 is a serpentine flow field.

[0052] In other embodiments, alternative flow field designs can be employed to optimize reactant distribution and product removal. These flow field designs can include, but are not limited to, parallel flow fields, interdigitated flow fields featuring dead-ended channels that force flow through the gas diffusion layer, dot-matrix flow fields, spiral flow fields, fractal flow fields, or hybrid designs combining elements of different flow field types.

[0053] The choice of flow field design can depend on factors such as desired pressure drop, reactant distribution uniformity, water management requirements, and overall cell performance goals. In some cases, the cathode and anode flow fields can utilize different flow field designs to address the specific needs of each electrode reaction.

[0054] In some embodiments, the cathode is a silver, and / or silver alloy nanoparticle as cathode catalyst layer 430 deposited on a first gas diffusion layer, and the anode is an IrCF, and / or mixed metal oxide (MMO) as anode catalyst layer 450 deposited or coated on a second diffusion layer.

[0055] In some embodiments, anion exchange membrane 440 is a Sustainion®anion exchange membrane manufactured by Dioxide Materials, PiperlON® manufactured by Versogen, Aemion® manufactured by lonomr, or similar materials.

[0056] In some embodiments, cathode flow field 410 has a feed of humidified CO2 gas which is electrochemically reduced to CO at cathode catalyst layer 430. In some embodiments, hydroxide (OH') ions co-produced at the cathode chemically react with the CO2 present in the cathode, forming bicarbonate / carbonate anions. In some embodiments, these anions then pass through anion exchange membrane 440 and react to form O2 and CO2 at anode catalyst layer 450, resulting in CO2 loss in O2 stream.

[0057] FIG. 4 illustrates an embodiment of electrolyzer 5000 configured to convert CO2 to CO. In some embodiments, such as shown in FIG. 4, electrolyzer 5000 includes cathode flow field 510, a cathode 590 comprising cathode gas diffusion layer 520 and cathode catalyst layer 530, an anion exchange membrane 540, anode 595 comprising anode catalyst layer 550 and anode gas diffusion layer 560, and anode flow field 570.

[0058] In some embodiments, electrolyzer 5000 includes in-situ carbon capture layer 580 between anion exchange membrane 540 and anode catalyst layer 550. In some embodiments, the in-situ carbon capture layer 580 is composed of regeneration layer 584 and barrier layer 588.

[0059] In some embodiments, electrolyzer 5000 is formed, at least in part, by using Dioxide Materials' 5 cm2formic acid electrolyzer hardware, which has a three-compartment design. A typical three-compartment design includes an anode compartment, a central compartment, and a cathode compartment.

[0060] In some embodiments, regeneration layer 584 is a porous ion exchange media. In some embodiments, barrier layer 588 is a cation exchange membrane(CEM). In some embodiments, a CEM is positioned to selectively impede the transport of carbonate and bicarbonate ions from cathode catalyst layer 530 to anode catalyst layer 550. The CEM facilitates the transport of cations, specifically protons, from the anode catalyst layer 550 to a regeneration layer 584. Within the regeneration layer, these protons react with retained anions, releasing CO2. In some embodiments, this in-situ captured CO2 is subsequently recycled to the cathode, at least in part, reducing, if not eliminating, CO2 loss.

[0061] In some embodiments, the CEM is either a perfluorosulfonic acid (PF SA) membrane or a hydrocarbon-based sulfonic acid (PFSA-free) membrane, such as but not limited to, a Nafion® or a Pemion® membrane manufactured by lonomr.

[0062] In some embodiments, the CEM is a CEM reinforced on porous substrate, such as but not limited to EPTFE, PEEK mesh, PPS mesh, and PPS felt.

[0063] In at least some embodiments, regeneration layer 584 comprises a cation ion exchange media, such as ion exchange resin beads and / or an acidic hydrogel. In at least some embodiments, the ion exchange media is a strong acid cation media that is acidified from a flow of hydrogen ions (H+) that is formed at and transported from the anode. In at least some embodiments, the ion exchange media is acidified continuously. In some embodiments, regeneration layer 584 includes an ion exchange resin fill such as, but not limited to, AmberLite™ resin and / or Dowex® resin.

[0064] In some embodiments, regeneration layer 584 includes a sulfonated hydrogel, wherein a porous layer structure of the sulfonated hydrogel replaces the cation ion exchange resin beads. In some embodiments, this allows for easier transportation and assembly of the cell.

[0065] In some embodiments, regeneration layer 584 requires an electrolyte to maintain ionic conductivity. In some embodiments, the electrolyte can be deionized water or an acid such as, but not limited to, sulfuric acid.

[0066] In at least some embodiments, the carbonate / bicarbonate is decomposed in the acidified ion exchange media, generating CO2. In some embodiments, the CO2 flows back through a porous anion exchange membrane 540 or ionomer coated porous layer where it can react to form CO.

[0067] In at least some embodiments, in-situ carbon capture layer 580 reduces, if not eliminates, the CO2 crossover. In some embodiments, less than 20%, more preferably less than 10%, even more preferably less than 5% of the CO2 is lost in the electrolyzer.

[0068] In some embodiments, electrolyzer 5000 omits anion exchange membrane 540 and regeneration layer 584. Instead, in some embodiments, a porous material such as, but not limited to, carbon fiber paper is coated with anion exchange ionomers and then sandwiched between barrier layer 588 and cathode catalyst layer 530. In at least some embodiments, designs using the coated carbon fiber paper are not three-compartment cells.

[0069] In at least some embodiments, electrolyzer 5000 does not include anion exchange membrane 540. In some embodiments, cathode catalyst layer 530 is treated to create a layer of anion exchange ionomer and put directly against regeneration layer 584. In at least some embodiments, electrolyzers using these designs are not three-compartment cells.

[0070] In some embodiments, regeneration layer 584 utilizes a strong acid resin, such as but not limited to AmberLite™ In some embodiments, regeneration layer 584 utilizes a weak acid resin such as, but not limited to, Dowex® resin.

[0071] In at least some embodiments, the thickness of regeneration layer 584 (cation ion exchange resin and / or hydrogel) can be reduced to 1-1.5 mm, preferably 0.5-1 mm, to reduce the total cell resistance.

[0072] In at least some embodiments of the electrolyzers, barrier layer 588 utilizes a CEM with a thinner thickness, specifically 100-200 pm, preferably 50- 100 pm, such as but not limited to, Nafion® membranes to reduce the total cell resistance.

[0073] In at least some embodiments, regeneration layer 584 uses an electrolyte such as, but not limited to, deionized water, diluted sulfuric acid, diluted potassium bicarbonate, and / or potassium carbonate.

[0074] In some embodiments, electrolyzer 5000 can be scaled up to a 1000 cm2single cell electrolyzer, 1000 cm2cell stack and / or stack arrays to meet commercial requirements.Specific Example 1

[0075] Specific Example 1 illustrates a procedure to create an electrolyzer with an in-situ capture layer such as shown in FIG. 4. Specific Example 1 demonstrated reduced CO2 crossover over earlier electrochemical cells used for CO2 conversion.

[0076] For Specific Example 1, measurements were conducted in an electrolysis cell with an anode, a carbon capture layer comprising of a cationconducting polymer electrolyte membrane and cation exchange media, an anion- conducting polymer electrolyte membrane and a cathode installed in Dioxide Materials’ 5cm2formic acid electrolysis cell hardware with serpentine flow fields.

[0077] The cathode in Specific Example 1 was prepared as follows: silver inkwas made by dispersing Ag nanoparticles and carbon powder in ethanol containing the Sustainion® XA-9 ionomer. Then the silver ink was spray-coated onto GDS 5130 (AvCarb). The silver loading was about 2mg / cm2. The catalyst layer was activated by floating the cathode with the catalyst layer facing downward, in a IM KOH solution for 2hr, followed by rinsing with deionized water to remove residual KOH.

[0078] The anode in Specific Example 1 was prepared as follows: IrO ink was made by mixing 15mg of IrO with 0.2ml deionized water, 0.2ml 1-proponal and 0.1ml of 5% Nafion dispersion (1100EW, DuPont, Wilmington, DE). Then the IrO ink was spray-coated onto carbon fiber paper (Toray, Japan). The IrO loading was about 1.5mg / cm2.

[0079] The anion conducting polymer electrolyte membrane in Specific Example 1 was a Sustainion® Grade-T membrane, an EPTFE reinforced anion exchange membrane.

[0080] The capture layer in Specific Example 1 included a regeneration layer (a cation exchange resin beads (AmberLite™ resin)) constrained in a plastic center compartment, and a barrier layer (a cation conducting polymer electrolyte membrane (Nafion, DuPont, Wilmington, DE)).

[0081] In Specific Example 1 , CO2 humidified at room temperature was fed into the cathode at a rate of 30 seem. A cutoff voltage of 4.2V with a maximum current density of 200mA / cm2was applied to the cell. The output gas composition was analyzed with an Agilent™ 6890 gas chromatograph with a thermal conductivity detector (GC-TCD) (Agilent Technologies, Santa Clara, CA) equipped with a Carboxen™ 1010 P LOT GC column (30 m x320um, Sigma Aldrich).

[0082] The cell produced a stable current of 150mA / cm2for up to 150hr. GCanalysis showed that the output from cathode, center and anode compartments contained a mixture of CO, H2 and CO2, almost pure CO2, a mixture of O2 and <5% CO2, respectively. CO selectivity was calculated at 95% where:CO prodcution rateSelectivity = - - - - -CO production rate + H2production rate

[0083] Pure CO2 from the center compartment could be fed to the cathode directly, so CO2 loss was calculated at 0.6% whereCO released in anodeCO2loss (%) = — - - — —CO2fed into catnode

[0084] Therefore, the carbon capture layer in Specific Example 1 is properly classified as a carbon capture layer blocking CO2 crossover.Comparative Example 1

[0085] Comparative Example 1 illustrates a procedure to create a state-of-the- art zero-gap AEM electrolyzer. The results of Comparative Example 1 demonstrate significant CO2 crossover by eliminating carbon capture layer in Specific Example 1.

[0086] GC analysis showed the output from anode contained 66% CO2 and 33% O2. The CO2 loss was calculated at 23.3%. The substantial CO2 loss, potentially reaching 50% with stoichiometric CO2 feed to the electrolyzer cathode, highlights the need for an innovative CO2 capture solution.Comparative Example 2

[0087] Comparative Example 2 illustrates a procedure to create an electrolysis cell with an in-situ carbon capture layer. In Comparative Example 2, aregeneration layer was replaced with a polyphenylene sulfide (PPS) fiber felt. The results of Comparative Example 2 demonstrate reduced CO2 crossover with the same barrier layer in Specific Example 1.

[0088] In Comparative Example 2, a PPS fiber felt (80% porosity, 15 pm thickness) was sulfonated with sulfuric acid to mimic cation exchange beads. 10- 100 layers, more preferably 20-80 layers, even more preferably 30-50 layers of PPS fiber felt were used to replace ion exchange resin beads in Specific Example 1 for simplified cell assembly.

[0089] In Comparative Example 2, 15 layers of sulfonated PPS felt was sandwiched between anion exchange membrane and cation exchange membrane. The current reached lOOmA / cm2at 4V, and CO2 loss was calculated at 1%.Specific Example 2

[0090] Specific Example 2 illustrates a procedure to create an electrolysis cell with an in-situ carbon capture layer. In Specific Example 2, an anion exchange membrane was replaced with anion exchange ionomer coated carbon fiber paper. Specific Example 2 demonstrated a reduced CO2 crossover with the same capture layer of Specific Example 1.

[0091] In Specific Example 2, an anion exchange ionomer coated carbon fiber paper was prepared by dipping carbon fiber paper (Toray, Japan) into an anion exchange ionomer solution (5% XA-9, Dioxide Materials) followed by drying at 80°C in an oven. The process was repeated until the desired loading was achieved.

[0092] In Specific Example 2, carbon fiber paper with a loading of lmg / cm2of Sustainion® ionomer was installed between cathode catalyst layer and cationexchange resin beads. The current reached 200mA / cm2at 4V, and CO2 loss was calculated at 1%.Specific Example 3

[0093] Specific Example 3 illustrates a procedure to create an electrolysis cell with an in-situ carbon capture layer. Here the anion exchange membrane was replaced with a porous anion exchange membrane supported on PEEK mesh and the regeneration layer was omitted. The results of Specific Example 3 demonstrate reduced CO2 crossover with the same barrier layer in Specific Example 1.

[0094] In Specific Example 3 a porous anion exchange ionomer-coated PEEK mesh, as described in Specific Example 3, was prepared by: applying a Sustainion polymer solution to a PET liner, forming a layer with a thickness of 10-200 pm, a preferred thicknesses of 20-100 pm and a more preferred thicknesses of 30-80 pm; subsequently, a PEEK mesh was positioned on the top of the layer; the composite was then dried at 60°C for one hour; and finally, the membrane was activated in IM KOH to convert the chloride form to the hydroxide form.

[0095] Similar to Specific Example 1, CO2 loss was significantly reduced to about 1% while still producing the desired product CO.Specific Example 4

[0096] Specific Example 4 illustrated a procedure to create an electrolysis cell with an in-situ carbon capture layer. In the example, the anion exchange membrane was omitted. Instead, a thin layer of an anion exchange membrane was directly coated on the catalyst layer. In the example, the regeneration layer wasalso omitted. The results of Specific Example 4 demonstrated significant CO2 crossover with the same barrier layer in Specific Example 1.

[0097] In Specific Example 4 a layer of anion exchange membrane on the cathode catalyst layer was prepared by spraying Sustainion polymer solution (manufactured by Dioxide Materials) on the surface of cathode catalyst layer. The thickness was about 5-100um, preferably 10-80um, even more preferably 20- 50um. The layer was then dried at 80C for 15min. The process was repeated until the desired thickness was achieved. The catalyst layer with a thin layer of anion exchange membrane was then activated by floating the membrane side facing down to IM KOH for 24hr, so CT was converted to OH' form. This layer had some porosity so that CO2 regenerated was reduced to CO directly at the cathode catalyst layer without external recycling. Similar to Specific Example 1, CO2 loss was reduced significantly to 1% while still producing the desired product CO.

[0098] While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood that the invention is not limited thereto since modifications can be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.

Claims

What is claimed is:Claim 1. An electrolyzer comprising: an anode flow field; an anode; a barrier layer; a regeneration layer; an anion exchange membrane or an ionomer coated porous layer; a cathode; and a cathode flow field.Claim 2. The electrolyzer of claim 1 wherein said anode comprises a catalyst layer comprising IrO nanoparticles painted on a first gas diffusion layer or a mixed metal oxide coated on a first gas diffusion layer.Claim 3. The electrolyzer of claim 1 wherein said barrier layer comprises a cation exchange membrane.Claim 4. The barrier layer of claim 3 wherein said cation exchange membrane comprises a self-standing and reinforced membrane.Claim 5. The electrolyzer of claim 1 wherein said regeneration layer comprises an ion exchange media.Claim 6. The electrolyzer of claim 5 wherein said ion exchange media comprises at least one of a plurality of cation exchange resin beads, a plurality of anion exchange resin beads, a sulfonated PPS fiber felt, and an acidic hydrogel.Claim 7. The electrolyzer of claim 1 wherein said anion exchange membrane is a self-standing membrane, a reinforced membrane or a porous anion exchange membrane.Claim 8. The electrolyzer of claim 1 wherein said anion exchange membrane comprises a benzyl group bonded to at least one of: an imidazolium, a pyridinium, a pyrazolium, a pyrrolidinium, a pyrrolium, a pyrimidium, a piperidinium, an indolium, a triazinium, a phosphonium or a quaternary amine.Claim 9. The electrolyzer of claim 7 wherein said reinforced membrane utilizes a porous support selected from the group consisting of EPTFE, PEEK mesh, PPS mesh and PPS felt.Claim 10. The electrolyzer of claim 7 wherein said porous anion exchange membrane utilizes a porous support selected from the group consisting of carbon fiber paper, PEEK mesh, PPS mesh and PPS felt.Claim 11. The electrolyzer of claim 7 wherein said porous anion exchange membrane is prepared by dipping porous support into an ionomer solution multiple times until a desired loading is reached.Claim 12. The electrolyzer of claim 7 wherein said porous anion exchange membrane is prepared by: applying a first polymer solution onto a PET liner to create an applied first polymer solution layer; subsequently placing a porous support onto said applied first polymer solution layer; and applying at least one additional polymer solution to achieve a desired membrane property.Claim 13. The electrolyzer of claim 1 wherein said cathode comprises a catalyst layer comprising Ag nanoparticles or Ag alloy nanoparticles painted on a second gas diffusion layer.Claim 14. The electrolyzer of claim 1 wherein said cathode comprises a thin layer of anion exchange ionomer with a thickness of 5-100um on top of a catalyst layer.Claim 15. The electrolyzer of claim 1 wherein said cathode comprises a thin layer of anion exchange ionomer with a thickness of 10-80um.Claim 16. The electrolyzer of claim 1 wherein said cathode comprises a thin layer of anion exchange ionomer with a thickness of 20-50um.Claim 17. The electrolyzer of claim 1 wherein the CO2 crossover to said anode is less than 20%.Claim 18. The electrolyzer of claim 1 wherein the CO2 crossover to said anode is less than 10%.Claim 19. The electrolyzer of claim 1 wherein the CO2 crossover to said anode is less than 5%.Claim 20. The electrolyzer of claim 1 wherein the CO2 crossover to said anode is less than 1%.Claim 21. The electrolyzer of claim 1, wherein at least one of the anode flow field or the cathode flow field comprises a flow field design selected from the group consisting of: a serpentine flow field, a parallel flow field, an interdigitated flow field, a spiral flow field, or a fractal flow field.Claim 22. The electrolyzer of claim 1, wherein the regeneration layer has a thickness of no more than 2 mm.Claim 23. A system comprising an electrolyzer.Claim 24. A method comprising running an electrolyzer.Claim 25. An electrolyzer comprising and in-situ carbon capture layer.

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