Membraneless electrochemical trickle bed reactor systems and methods of their use

Abstract

An electrolyzer system is provided with a plurality of separator-electrode assemblies (SEA). The SEAs include a negative electrode, a positive electrode, and a porous separator positioned therebetween. The electrodes and the separator, and thus the SEA overall, have a flow-through configuration enabling bulk liquid- and gas-phase reactants and products to flow therethrough. SEAs are positioned serially along a length of the electrolyzer, and thus bulk flow occurs through each SEA cell sequentially, in contrast to "flow-by" architectures where flow occurs in parallel through all cells simultaneously. Liquid- and gas-phase inlets provide the reactants such as H2, CO2, O2, etc. which are electrochemically converted to value products by the SEAs and concentrated for removal by product outlets. These electrolyzer systems generate value products such as H2O2; epoxides; C2+ alcohols, such as ethanol; syngas (CO + H2); etc. even at room temperature while avoiding the disadvantages associated with degradation-prone polymeric ion exchange membranes.

Description

Atorney Docket No.: 105041-201MEMBRANELESS ELECTROCHEMICAL TRICKLE BED REACTOR SYSTEMS AND METHODS OF THEIR USECROSS REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 708,015, filed October 16, 2024, and U.S. Provisional Application No. 63 / 900,301, filed October 16, 2025, which are incorporated by reference as if disclosed herein in their entireties.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

[0002] This invention was made with government support under DE-AR0001952 awarded by the U.S. Department of Energy. The government has certain rights in the invention.BACKGROUND

[0003] Electrolysis is an industrial process used to produce a variety of useful chemical building blocks. Processes such as the chlor-alkali process, electro- synthesis of anthraquinone, and electro-fluoridation all play roles in the production of chemicals used in our everyday lives. Electrolysis can be an energy efficient process with a significantly lower carbon footprint compared to traditional thermal catalysis processes, e.g., if the input electricity is derived from a renewable resource such as wind or solar. As of 2006, chemical production by electrochemical processes made up more than 6% of the total electrical generating capacity of the United States, with the most energy intensive process as being performed by the chlor-alkali industry. These processes can be used to produce hydrogen gas, caustic soda (sodium hydroxide), and chlorine gas. For the chloralkali processes, and most electrolysis processes, the economics are dominated by the cost of electricity, which accounts for a significant fraction of the total manufacturing cost. However, the decreasing costs of electricity from renewable resources and the continued adoption of time-of-use pricing schemes are likely to change the economics of electrochemical processes, shifting importance towards decreasing the capital cost of the electrolyzer system itself.

[0004] Current industrial-scale electrolyzers such as carbon dioxide electrolyzers or epoxidation reactions that produce hydrogen peroxide are expensive, inefficient, have a high carbon footprint, or utilize membranes that are prone to degradation. The membrane132570368.1Atorney Docket No.: 105041-201 electrolyzer functions by separating anolyte and catholyte streams by means of an ion selective membrane and that only allows cationic species (e.g. Na+, K+, H+) and small amounts of water to pass through it. Diaphragm electrolyzers and mercury electrolytic cells are also used to produce bases, although these technologies are being phased out in favor of membrane reactors. This is due to health and environmental concerns relating to the use of asbestos and mercury, respectively.

[0005] Ethanol is an important fuel for United States vehicles and aviation. In 2024, 14.2 billion gallons of ethanol was blended into vehicles and the United States’ first Alcohol-to- Jet (ATJ) plant opened, paving the way for ethanol-derived aviation fuel that is projected to hit 1.84 billion gallons by 2032.

[0006] Meanwhile, epoxides are important in the chemical, pharmaceutical, and polymer industries, with a market size of approximately $20 billion to $50 billion for ethylene oxide and propylene oxide. Current thermal-catalytic methods for producing epoxides are energy- intensive and / or generate toxic byproducts and waste or exhibit low conversion per pass. Alternatively, the electrochemical production of epoxides mediated by in situ -generated H2O2 provides a sustainable pathway for carrying out the epoxidation reaction using renewable electricity. However, conventional electrochemical methods face issues related to membranes and ionomer durability in the presence of strong oxidants like II2O2, undesired side products such as halogenated organics, and reagent toxicity from halides or the short lifetime of green oxidant H2O2.

[0007] Epoxides such as propylene oxide are important industrial intermediates that are used to produce a variety of fine chemicals, such as unsaturated resins, surfactants, and polyurethane plastics. The current methods of epoxide production, such as the hydrogen peroxide propene oxide (HPPO) process, tend to be energy intensive and environmentally unfriendly due to the generation of toxic by-products and wastes. While the HPPO process itself tends to be more environmentally friendly than alternatives, the current anthraquinone process used for hydrogen peroxide (H2O2) production is also energy intensive and generates a large amount of waste. The hydrogen peroxide produced is also prone to decomposition and formation of explosive mixtures during transportation. In recent years, electrochemical production of I I2O2 has shown promise due to its potential for low energy requirements and feasibility for on-site production. However, electrochemical production of H2O2 is232570368.1Atorney Docket No.: 105041-201 challenging when using conventional electrolyzers with polymeric membranes, which are prone to degradation by reactive H2O2

[0008] Although various approaches have been pursued in order to improve the yield, energy efficiency, economics, and environmental impacts, the use of membrane electrolyzers in manufacture of value products such as ethanol and epoxides has been hindered by the high cost of the ion-selective membranes and their susceptibility to fouling. What is desired, therefore, are simplified and robust electrolyzer systems for generating value products.SUMMARY

[0009] Aspects of the present disclosure are directed to an electrolyzer including a reactant inlet, a product outlet, an electrolyzer body having a longitudinal dimension extending from the reactant inlet to the product outlet, and a separator-electrode assembly (SEA) positioned between the reactant inlet and the product outlet. In some embodiments, the SEA includes a first electrode, at least a second electrode, and a separator positioned between the first electrode and the second electrode. In some embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode. In some embodiments, the first electrode, the separator, and the second electrode are arranged serially along the longitudinal dimension. In some embodiments, the reactant inlet is in fluid communication with a liquidphase reactant source and the at least a second inlet is in communication with a gas-phase reactant source.

[0010] In some embodiments, the electrolyzer includes two or more SEAs arranged serially between the reactant inlet and the product outlet. In some embodiments, the SEA further includes a third electrode positioned between the first electrode and the second electrode, a first separator positioned between the first electrode and the third electrode, and a second separator positioned between the second electrode and the third electrode, wherein the first and second electrodes are positive electrodes and the third electrode is a negative electrode. In some embodiments, the SEA includes a plurality of flow-through channels from a surface of the first electrode to a surface of the second electrode. In some embodiments, the SEA includes one or more catalysts positioned on the first electrode, second electrode, or combinations thereof.

[0011] In some embodiments, the electrolyzer includes at least a second reactant inlet positioned on an inlet-facing surface of the SEA and proximate the first electrode. In some332570368.1Atorney Docket No.: 105041-201 embodiments, the electrolyzer includes at least a second inlet positioned on an outlet-facing side of the SEA. In some embodiments, the electrolyzer includes a porous manifold configured to radially distribute within the electrolyzer body reactant from reactant inlet.

[0012] Aspects of the present disclosure are directed to a membraneless electrolyzer system. In some embodiments, the system includes a source of gas-phase reactants; a source of liquid-phase reactants; and an electrolyzer. As discussed above, in some embodiments, the electrolyzer includes a first reactant inlet; a second reactant inlet; a product outlet; an electrolyzer body having a first end, a second end, and a longitudinal dimension extending from the first end to the second end; and at least two SEAs positioned between the first reactant inlet and the product outlet and arranged serially along the longitudinal dimension. In some embodiments, the SEAs include a first electrode; a second electrode; and a separator positioned between the first electrode and the second electrode, wherein the first electrode, the separator, and the second electrode are arranged serially along the longitudinal dimension.

[0013] In some embodiments, the electrolyzer body is arranged vertically such that the second end is positioned below the first end, such that the electrolyzer includes a first product outlet positioned below the SEAs and a second product outlet positioned above the SEAs. In some embodiments, the first product outlet is in fluid communication with a liquid-phase product stream and the second product outlet is in fluid communication with a gas-phase product stream. In some embodiments, the liquid-phase reactants include one or more alkenes, the gas-phase reactants include oxygen, and the product outlet is in fluid communication with a product stream including concentrations of H2O2, epoxidized alkenes, or combinations thereof. In some embodiments, the system includes a recycle stream in fluid communication with the product outlet and the first reactant inlet.

[0014] Aspects of the present disclosure are directed to a membraneless electrolyzer system including a source of gas-phase reactants; a source of liquid phase-reactants; and an electrolyzer. In some embodiments, the electrolyzer includes an electrolyzer body having a first end, a second end, a longitudinal dimension extending from the first end to the second end, and a radial dimension; a liquid-phase reactant inlet proximate the first end; at least one gas-phase inlet positioned proximate the second end; a product outlet proximate the second end; at least two SEAs positioned between the first reactant inlet and the product outlet and arranged serially, and at least one porous manifold configured to distribute in the radial dimension liquid-phase reactant, gas-phase reactant, or combinations thereof. In some432570368.1Atorney Docket No.: 105041-201 embodiments, the system includes a source of H2 in fluid communication with the at least one gas-phase inlet; a source of carbon dioxide in fluid communication with the liquid-phase reactant inlet, gas-phase inlet, or combinations thereof.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings show embodiments of the disclosed subject matter for the purpose of illustrating the invention. However, it should be understood that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

[0016] FIGs. 1A-1C are schematic representations of an electrolyzer according to some embodiments of the present disclosure;

[0017] FIG. 2 is a schematic representation of a membraneless electrolyzer system according to some embodiments of the present disclosure;

[0018] FIG. 3 A is a graph portraying the effect of varying hydrogen gas flow rates on current and voltage profiles in electrolyzer systems according to embodiments of the present disclosure performing hydrogen evolution and hydrogen oxidation reactions;

[0019] FIG 3B is a graph portraying the effect of carbon dioxide introduction on electrolyzer systems according to embodiments of the present disclosure performing hydrogen evolution and hydrogen oxidation reactions;

[0020] FIG. 3C is a graph portraying the effect of liquid reactant flow rate on electrolyzer systems according to embodiments of the present disclosure performing hydrogen evolution and hydrogen oxidation reactions; and

[0021] FIG. 4 is a graph portraying the effect of copper catalyst loading on electrolyzer systems according to embodiments of the present disclosure configured for the production of C2+ alcohols.DETAILED DESCRIPTION

[0022] Referring now to FIG. 1 A, some embodiments of the present disclosure are directed to an electrolyzer 100 for producing one or more products. In some embodiments,532570368.1Atorney Docket No.: 105041-201 electrolyzer 100 includes one or more reactant inlets 102. Reactant inlets 102 are positioned and configured to provide desired reactants to electrolyzer 100 for conversion into one or more products. In some embodiments, electrolyzer includes one or more product outlets 104. Product outlets 104 are positioned and configured to remove desired products from electrolyzer 100.

[0023] In some embodiments, electrolyzer 100 includes an electrolyzer body 106. In some embodiments, electrolyzer body 106 includes an electrolyzer cavity 108. In some embodiments, side walls 106S define the cross-sectional shape and / or size of electrolyzer cavity 108. In some embodiments, reactant inlets 102 are positioned and configured to provide desired reactants to electrolyzer cavity 108. In some embodiments, product outlets 104 are positioned and configured to remove desired products from electrolyzer cavity 108. In some embodiments, electrolyzer body 106 and / or electrolyzer cavity 108 include a longitudinal dimension L and radial dimension R. In some embodiments, longitudinal dimension L of electrolyzer body 106 extends from a first end 106 A to a second end 106B. In some embodiments, longitudinal dimension L extends generally in the direction from a first reactant inlet 102 A to a first product outlet 104 A. In some embodiments, longitudinal dimension L of electrolyzer 106 is larger than radial dimension R. In some embodiments, electrolyzer body 106 has a generally vertical orientation, i.e., first end 106A is positioned above second end 106B or vice versa, longitudinal dimension L is not parallel to a level surface upon which electrolyzer 100 is positioned, etc. Electrolyzer body 106 and / or electrolyzer cavity 108 can have any desired cross-sectional shape and size to facilitate conversion of reactants into one or more products, e.g., cylindrical, cuboid, etc.

[0024] In some embodiments, electrolyzer 100 includes one or more separator-electrode assemblies (SEA) 110. In some embodiments, SEA 110 includes a first electrode 110A. In some embodiments, SEA 110 includes a second electrode HOB. In some embodiments, first electrode 110A is a negative electrode and second electrode 110B is a positive electrode. In some embodiments, first electrode 110A is a positive electrode and second electrode 110B is a negative electrode. In some embodiments, the negative electrode is a cathode. In some embodiments, the positive electrode is an anode. In the exemplary embodiments discussed below, first electrode 110A is generally shown as a negative electrode and a cathode, while second electrode 110B is generally shown as a positive electrode and an anode, however the present disclosure is not intended to be limited to this particular arrangement, as other632570368.1Atorney Docket No.: 105041-201 arrangements of cathodes and anodes can be implemented according to the desired electrolyzer operation parameters and resulting products, as would be understood by those of ordinary skill in the art in view the balance of the present disclosure. In some embodiments, SEA 110 includes a separator 110C. In some embodiments, separator 110C is positioned between first electrode 110A and second electrode HOB. In some embodiments, separator 110C is composed of one or more polymers. In some embodiments, separator 110C is composed of polycarbonate, polyether sulfone (PES), polytetrafluoroethylene (PTFE), cellulose, or combinations thereof. In some embodiments, separator 110C is a track etched membrane. In some embodiments, separator 110C is deposited as a thin layer directly on one of first electrode 110A and second electrode HOB, which support the separation layer. In some embodiments, separator 110C is a polycarbonate track etched membrane. In some embodiments, separator 110C is a thin PES layer deposited directly on one of first electrode 110A and second electrode 110B. In some embodiments, separator 110C has a thickness of about 2 mm, 1.5 mm, 1 mm, 900 pm, 800 pm, 700 pm, 600 pm, 500 pm, 400 pm, 300 pm, 200 pm, 100 pm, 50 pm, 40 pm, 30 pm, 20 pm, 10 pm, etc. In some embodiments, separator HOC has a thickness below about 100 pm, 50 pm, 40 pm, 30 pm, 20 pm, or 10 pm.

[0025] Electrodes and separators included in SEA 110 have a “flow-through” construction, i.e., are sized and configured to allow bulk flow of liquid- and gas-phase reactants / products therethrough. In addition to the improved electrochemical performance, the thin, porous separators create the least backpressure, which we can be beneficial when building multicell stacks with flow of electrolyte through each cell in the stack. In some embodiments, electrodes in SEA 110 are composed of a wire mesh. Referring specifically to FIG. IB, SEA 110 includes a plurality of flow-through channels 110'. In some embodiments, flow-through channels 110' extend from a surface of first electrode 110A, e.g., 110A', to a surface of the second electrode HOB, e.g., 110B'.

[0026] Referring specifically to FIG. 1C, in some embodiments, SEA 100 includes a first electrode 110A, a second electrode HOB, and a third electrode 110D positioned between first electrode 110A and second electrode 110B. In some embodiments, first electrode 110A and second electrode 110B are positive electrodes and third electrode 110C is a negative electrode. In some embodiments, first electrode 110A and second electrode 110B are negative electrodes and third electrode 110C is a positive electrode. In some embodiments, a732570368.1Atorney Docket No.: 105041-201 first separator, e.g., separator 110C, is positioned between first electrode 110A and third electrode HOD, and a second separator, e.g., separator 110E, is positioned between third electrode HOD and second electrode 110B.

[0027] In some embodiments, SEA 110 is positioned within electrolyzer body 106. In some embodiments, SEA 110 is positioned within electrolyzer cavity 108. SEA 110 are positioned and arranged such that bulk liquid- and gas-phase reactants / products flow through the SEA, e.g., through first electrode 110A to separator 110C, through the separator to second electrode HOB, and then through the second electrode. In contrast to a flow-by architecture, where electrolyte flows in parallel through all cells simultaneously, in a flow through design the electrolyte can flow through every cell sequentially. In some embodiments, SEA 110 is positioned within electrolyzer body 106 between first end 106 A and second end 106B. In some embodiments, SEA 110 is positioned between a first reactant inlet 102A and a first product outlet 104A. In some embodiments, SEA 110 extends between side walls 106S. In some embodiments, the layers of SEA 110, e.g., first electrode 110A, second electrode HOB, separator 110C, etc., are arranged serially. In some embodiments, the layers of SEA 110, e.g., first electrode 110A, second electrode HOB, separator HOC, etc., are arranged serially between first reactant inlet 102 A and first product outlet 102B. In some embodiments, the layers of SEA 110, e.g., first electrode 110A, second electrode HOB, separator 110C, etc., are arranged serially along longitudinal dimension L. In some embodiments, the layers of SEA 110, e.g., first electrode 110A, second electrode HOB, separator 110C, etc., are arranged non-parallel to longitudinal dimension L, e.g., in contrast to traditional “flow-by” electrolyzers. In some embodiments, the layers of SEA 110, e.g., first electrode 110A, second electrode HOB, separator HOC, etc., are arranged at least substantially parallel to radial dimension R.

[0028] Referring specifically to FIG. 1 A, in some embodiments, electrolyzer 100 includes two or more SEAs 110. In some embodiments, SEAs 110 are arranged serially. In some embodiments, SEAs 110 are arranged serially along longitudinal dimension L. In some embodiments, electrolyzer 100 includes at least 3 SEAs. In some embodiments, electrolyzer 100 includes at least 4 SEAs. In some embodiments, electrolyzer 100 includes at least 5 SEAs.

[0029] Still referring to FIGs. 1 A-1C, as discussed above, in some embodiments, electrolyzer 100 includes one or more reactant inlets 102 and one or more product832570368.1Atorney Docket No.: 105041-201 outlets 104. In some embodiments, at least a first reactant inlet, e.g., 102A, is positioned on an “upstream side” of SEA 110, e.g., region U, while at least a first product outlet 104 is positioned on a “downstream side” of SEA 110, e.g., region D. In some embodiments, SEAs 110 are arranged serially between first reactant inlet 102 A and first product outlet 104 A. In some embodiments, SEAs 110 are arranged serially from region U towards region D.

[0030] In some embodiments, at least one reactant inlet is positioned in region U. In some embodiments, two or more reactant inlets are positioned in region U. In some embodiments, first end 106A is positioned in region U and second end 106B is positioned in region D. In some embodiments, at least one reactant inlet is positioned in first end 106A. In some embodiments, at least one reactant inlet is positioned proximate first end 106A. In some embodiments, at least one reactant inlet is positioned to directly deliver reactant to a surface of SEA 110, e.g., surface 110A'. In some embodiments, at least one reactant inlet is positioned proximate a first electrode 110A of SEA 110. In some embodiments, at least one reactant inlet is positioned in region D. In some embodiments, at least one product outlet is positioned on second end 106B. In some embodiments, at least one product outlet is positioned proximate second end 106B.

[0031] In some embodiments, reactant inlets 102 are in fluid communication with a liquidphase reactant source, a gas-phase reactant source, or combinations thereof. In some embodiments, a first reactant inlet is in fluid communication with a liquid-phase reactant source, and a second reactant inlet is in fluid communication with a gas-phase reactant source. In some embodiments, electrolyzer 110 includes one or more porous manifolds 112 configured to radially distribute reactants supplied by reactant inlets 102 within electrolyzer body 106, e.g., along radial dimension R in electrolyzer cavity 108.

[0032] The compositions of the liquid-phase reactant and gas-phase reactant sources are configured to administer the desired reactants to SEAs 110 for electrochemical conversion to one or more products. In an exemplary embodiment for the production of ethanol, a feedstream of water is provided to electrolyzer cavity 108, e.g., via first reactant inlet 102A positioned in region U. A concentration of CO2 is also provided to electrolyzer cavity 108. In some embodiments, the CO2 is provided in a gas phase via an inlet, e.g., positioned in region D. In some embodiments, the CO2 is provided as a liquid-phase bicarbonate stream laden with CO2, e.g., via an inlet in region U. Finally, a concentration of H2 gas is provided932570368.1Atorney Docket No.: 105041-201 to electrolyzer cavity 108, e.g., via a reactant inlet 102 positioned in region D. When a voltage is applied across the cathode, e.g., 110A, and anode, e.g., HOB, as liquid- and gasphase reactants flow through those electrodes, a redox reaction occurs resulting in the generation of catholyte at cathode 110A and anolyte at anode HOB. In some embodiments, the applied voltage is substantially constant. In some embodiments, the applied voltage is pulsed. In some embodiments, the voltage is applied by a power source through one or more current collectors (not pictured).

[0033] In this exemplary embodiment, CO2 is reduced to ethanol at the cathode in SEA 110 while H2 gas is oxidized at the anode of SEA 110. Because SEAs 110 have a flow-through configuration and are arranged serially along longitudinal dimension L of electrolyzer 100, transport of evolved species such as ethanol and H+is not blocked by the SEA. Ethanol- laden liquid phase is allowed to pass from cathode 110A through separator 110C and anode 110B. Additionally, the ethanol is not reoxidized at anode 110B due to the low anode potential used for H2 oxidation. As a result, the concentration of ethanol is allowed to increase through region D. Ethanol products can then be withdrawn from electrolyzer 100 via product outlet 104. The ethanol product can be isolated, and recovered liquid, e.g., water, can be recycled to electrolyzer 100, e.g., at reactant inlet 102. Meanwhile, unreacted gases in region U that are no longer in contact with SEAs 110 can be withdrawn and recycled back to electrolyzer cavity 108 to contact the SEAs and generate further reaction products.

[0034] In another exemplary embodiment, a liquid feedstream of water and liquid alkenes is provided to electrolyzer cavity 108, e.g., via a reactant inlet 102 positioned in region U. A concentration of O2, e.g., via a stream of air, is also administered to electrolyzer cavity 108. In some embodiments, the O2 is provided directly proximate to cathode, e.g., 110A, of an SEA 110. In some embodiments, the O2 is bubbled into electrolyzer cavity 108 via a reactant inlet 102 positioned in region D. In this exemplary embodiment, O2 is reduced to H2O2 at cathode 110A while water is oxidized to H2O2 at anode 110B. The alkenes can then be oxidized by the H2O2 to epoxides at cathode 110A of the same or adjacent SEAs 110 in the presence of epoxidation catalysts. H2O2 and epoxide products can be withdrawn from electrolyzer 100, e.g., via product outlet 104. H2O2 and / or epoxide products can be isolated and recovered liquid, e.g., water, H2O2, etc., can be recycled to electrolyzer 100, e.g., at reactant inlet 102, for production of additional epoxides.1032570368.1Atorney Docket No.: 105041-201

[0035] Scalability is significant challenge faced by traditional “flow-by” electrodes, hindered by the large concentration gradients and resulting non-uniform current distributions that arise along the length of the electrodes. Electrolyzers consistent with embodiments of the present disclosure utilize horizontally-oriented flow-through electrodes for which reactants flow through rather than along the electrode surface. As a result, lateral concentration gradients and current distributions can be minimized, even at large scales. Further, the intentional crossover of reactants and products between electrodes as a result of the serial orientation of the electrodes and adjacent SEAs is well-suited for minimizing separator distances, and therefore cell resistance.

[0036] The particular composition of SEA 110 can depend on the desired products recovered from the reactants. In some embodiments, electrodes in SEA 110, e.g., 110A, HOB, 110C, are composed of copper, carbon, platinum, stainless steel, titanium, nickel, or combinations thereof. In some embodiment, SEA 110 include one or more catalysts, e.g., coating electrodes 110A, HOB, 110C, etc. In some embodiments, the one or more catalysts are monoatomic. In some embodiments, the one or more catalysts are ethanol-forming catalysts, epoxide-forming catalysts, syngas-forming catalysts, etc. In some embodiments, the one or more catalysts include copper, platinum, ruthenium, nickel, gallium, silver, oxidized carbon, iridium oxide, etc., or combinations thereof. In some embodiments, the catalyst loading is at least 0.1 mg / cm2, 0.2 mg / cm2, 0.3 mg / cm2, 0.4 mg / cm2, 0.5 mg / cm2, 1 mg / cm2, 2 mg / cm2, etc.

[0037] Referring now to FIG. 2, some embodiments of the present disclosure are directed to a membraneless electrolyzer system 200. In some embodiments, system 200 includes a source of gas-phase reactants 202. In some embodiments, the gas-phase reactants include CO2, EE, O2, etc., or combinations thereof, depending on the desired product from system 200. In some embodiments, source 202 includes a source of EE. In some embodiments, source 202 of EE is a water electrolyzer. In some embodiments, source 202 includes a source of CO2. In some embodiments, source 202 of CO2 is effluent from an industrial process, e.g., flue gas. In some embodiments, system 200 includes a source of liquid-phase reactants 204.

[0038] As discussed above, source of gas-phase reactants 202 and source of liquid-phase reactants 204 are in fluid communication with an electrolyzer 206. The structure of electrolyzer 206 is consistent with electrolyzer 100 discussed above. In some embodiments, electrolyzer 206 has a first end 206 A and a second end 206B. In some embodiments,1132570368.1Atorney Docket No.: 105041-201 electrolyzer 206 is positioned vertically, such that second end 206B is positioned below first end 206A. In some embodiments, electrolyzer 206 has a plurality of SEAs 206C.SEAs 206C are consistent with the structures of SEAs 110 described above. In some embodiments, electrolyzer 206 has a plurality of SEAs 206C arranged serially between first end 206 A and second end 206B.

[0039] In some embodiments, liquid-phase reactants from liquid-phase reactant source 204 are administered to electrolyzer 206 via a first reactant inlet 206D, e.g., at first end 206A. In some embodiments, the liquid flow rate to electrolyzer 206 is about 5 mL / min, 4 mL / min, 3 mL / min, 2, mL / min, 1 mL / min, .5 mL / min, etc. In some embodiments, gas-phase reactants from gas-phase reactant source 202 are administered to electrolyzer 206 via a second reactant inlet 206E, e.g., at second end 206B. In some embodiments, the flow rate of gas-phase reactant is 5 seem, 10 seem, 15, seem, 20 seem, 25, seem, 30 seem, 35 seem, etc. In some embodiments, the flow rate of gas-phase reactant is greater than 35 seem. In some embodiments, the flow rate of each gas-phase reactant is 5 seem, 10 seem, 15, seem, 20 seem, 25, seem, 30 seem, 35 seem, etc. In some embodiments, the flow rate of each gasphase reactant is greater than 35 seem. In some embodiments, flow rate of each gas-phase reactant is greater than 35 seem and the flow rate of the liquid-phase reactants is 1 mL / min or below. In some embodiments, electrolyzer includes one or more porous manifolds 206F configured to radially distribute within electrolyzer 206 reactant from the first reactant inlet, the second reactant inlet, or combinations thereof. In some embodiments, products from SEAs 206C are removed from electrolyzer 206 via one or more product outlets 206G. In some embodiments, electrolyzer 206 includes a first product outlet positioned below SEAs 206C, e.g., for removing liquid products from second end 206B, and a second product outlet positioned above SEAs 206C, e.g., for removing gas products from first end 206A. In some embodiments, system 200 includes one or more recycle streams 208 to recycle products from electrolyzer 206 to generate additional product. In some embodiments, recycle stream 208 is in fluid communication, e.g., with product outlets, e.g., 206G, and reactant inlets, e.g., 206D, 206E, etc.

[0040] In some embodiments, the liquid-phase reactants include water, aqueous electrolyte, e.g., KHCO3, liquid alkenes, etc., depending on the desired product from system 200. In some embodiments, source 204 includes a source of CO2. In some embodiments, source 204 of CO2 is a CO2 capture unit supplying CCh-laden aqueous bicarbonate. In some1232570368.1Atorney Docket No.: 105041-201 embodiments, the liquid-phase reactants include water and one or more alkenes, the gasphase reactants include oxygen, and the product outlet is in fluid communication with a product stream 210 including concentrations of H2O2, epoxidized alkenes, or combinations thereof. In some embodiments, the liquid-phase reactants include water, CCh-laden aqueous bicarbonate, or combinations thereof; the gas phase includes H2 and CO2; and the product outlet is in fluid communication with a product stream 210 including concentrations of ethanol. In some embodiments, the liquid-phase reactants include water, CCh-laden aqueous bicarbonate, or combinations thereof; the gas phase includes H2 and CO2; and the product outlet is in fluid communication with a product stream 210 including concentrations of syngas.EXAMPLES

[0041] A single electrolyzer cell consistent with the above-identified description was constructed. Gas-phase reactants included mixed H2 and CO2, while liquid phase-reactants included 3 M KHCO3. In the SEA, the cathode was composed of Cu mesh, the anode was composed of Pt mesh, and the separator was composed of PTFE. Introducing gas-phase reactants from a side port caused backflow of electrolyte due to pressure buildup at the top of the liquid-phase inlet. In contrast, a top-down gas-inlet design provided better gas-liquid separation and mixing and improving system sealing.

[0042] Referring now to FIGs. 3A-3C, exemplary testing employing hydrogen evolution (HER) and hydrogen oxidation reactions (HOR) was performed. Increasing the hydrogen gas flow rate from 20 seem to 100 seem resulted in negligible changes in both current and voltage profiles, indicating that 20 seem of H2 is sufficient for HOR consumption (see FIG. 3 A). When CO2 was introduced into the reaction system, the current density decreased significantly (see FIG. 3B). Without wishing to be bound by theory, this can be attributed to CO2 adsorption, leading to increased resistance. Referring specifically to FIG. 3C, the exemplary electrolyzer remained stable at flow rates below 4 mL / min, with 2 mL / min providing the highest current density.

[0043] Referring now to FIG. 4, additional testing of single electrolyzer cells consistent with the above-identified description was performed to demonstrate ethanol production. The exemplary electrolyzers included varying loadings of Cu coating on cathodes in the SEA. The anode catalyst included Pt (lOOmesh) support on a titanium current collector. The1332570368.1Atorney Docket No.: 105041-201 electrode geometric area was 1 cm2. The flow rate of the liquid-phase reactant, 3M KHCO3, was maintained at 2 mL / min. The flow rates of gas-phase reactants, H2 and CO2, were maintained at 20 seem for each gas. Liquid products were collected over periods shorter than 7 minutes and analyzed using nuclear magnetic resonance spectroscopy.

[0044] When operated at a constant current density of 100 mA / cm2and room temperature, the production of non-hydrogen products increased with increasing Cu loading. At a cathode catalyst loading of 1.5 mg / cm2, the ethanol Faradaic efficiency (FE) reached 32%. When accounting for the production of propanol (PrOH), the total FE% towards C2+ alcohols was about 43%. The FE for CO remained below 5%, consistent with trends observed in conventional flow-cell systems.

[0045] Systems and methods of the present disclosure advantageously provide electrolyzer systems for the manufacture of value products without the use of a membrane. The serial arrangement and flow-through configuration of the SEAs provides simplified and scalable construction of the electrolyzers, as well as control over product evolution streams. Selective production of products including H2O2; epoxides; C2+ alcohols, such as ethanol; syngas, e.g., CO+H2; etc. is realized via facile control over reactant streams and SEA compositions.Further, the electrolyzers avoid the disadvantageous reliability and performance characteristics associated with degradation-prone polymeric ion exchange membranes.

[0046] The electrolyzers can be operated at reduced temperatures, e.g., below 80 °C, improving energy efficiency and enabling advantageous dynamic operation in off-grid settings. Electrolyzer systems consistent with the present disclosure provide opportunities to lower cost and improve energy efficiency for value products for a wide range of industrial applications, ranging from pulp and paper processing (bleaching) to water treatment and the production of sodium percarbonate.

[0047] Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.1432570368.1

Claims

Atorney Docket No.: 105041-201CLAIMSWhat is claimed is:

1. An electrolyzer, comprising: a reactant inlet; a product outlet; an electrolyzer body having a longitudinal dimension extending from the reactant inlet to the product outlet; and a separator-electrode assembly (SEA) positioned between the reactant inlet and the product outlet, the SEA including: a first electrode; at least a second electrode; and a separator positioned between the first electrode and the second electrode, the first electrode, the separator, and the second electrode are arranged serially along the longitudinal dimension.

2. The electrolyzer according to claim 1, further comprising: at least a second reactant inlet positioned on an inlet-facing surface of the SEA and proximate the first electrode; at least a second inlet positioned on an outlet-facing side of the SEA, or combinations thereof.

3. The electrolyzer according to claim 2, wherein the reactant inlet is in fluid communication with a liquid-phase reactant source and the at least a second inlet is in communication with a gas-phase reactant source.

4. The electrolyzer according to claim 1, wherein the electrolyzer includes two or more SEAs arranged serially between the reactant inlet and the product outlet.1532570368.1Atorney Docket No.: 105041-2015. The electrolyzer according to claim 1, further comprising a porous manifold configured to radially distribute within the electrolyzer body reactant from reactant inlet.

6. The electrolyzer according to claim 1, wherein the first electrode is a negative electrode and the second electrode is a positive electrode.

7. The electrolyzer according to claim 1, wherein the SEA further includes a third electrode positioned between the first electrode and the second electrode, a first separator positioned between the first electrode and the third electrode, and a second separator positioned between the second electrode and the third electrode, wherein the first and second electrodes are positive electrodes and the third electrode is a negative electrode.

8. The electrolyzer according to claim 1, further comprising a plurality of flow-through channels from a surface of the first electrode to a surface of the second electrode.

9. The electrolyzer according to claim 1, further comprising one or more catalysts positioned on the first electrode, second electrode, or combinations thereof.

10. A membraneless electrolyzer system comprising: a source of gas-phase reactants; a source of liquid-phase reactants; and an electrolyzer including: an electrolyzer body having a first end, a second end, and a longitudinal dimension extending from the first end to the second end; a first reactant inlet; a second reactant inlet; a product outlet;1632570368.1Atorney Docket No.: 105041-201 at least two separator-electrode assemblies (SEA) positioned between the first reactant inlet and the product outlet and arranged serially along the longitudinal dimension, the SEA including: a first electrode; a second electrode; and a separator positioned between the first electrode and the second electrode, wherein the first electrode, the separator, and the second electrode are arranged serially along the longitudinal dimension.

11. The membraneless electrolyzer system according to claim 10, wherein the electrolyzer body is arranged vertically such that the second end is positioned below the first end, wherein the electrolyzer includes a first product outlet positioned below the SEAs and a second product outlet positioned above the SEAs, and wherein the first product outlet is in fluid communication with a liquid-phase product stream and the second product outlet is in fluid communication with a gas-phase product stream.

12. The membraneless electrolyzer system according to claim 10, wherein the first electrode is a negative electrode and the second electrode is a positive electrode.

13. The membraneless electrolyzer system according to claim 10, wherein the SEAs further include a third electrode positioned between the first electrode and the second electrode, a first separator positioned between the first electrode and the third electrode, and a second separator positioned between the second electrode and the third electrode, wherein the first and second electrodes are positive electrodes and the third electrode is a negative electrode.1732570368.1Atorney Docket No.: 105041-20114. The membraneless electrolyzer system according to claim 10, further comprising a plurality of flow-through channels from a surface of the first electrode to a surface of the second electrode.

15. The membraneless electrolyzer system according to claim 10, further comprising one or more catalysts positioned on the first electrode, second electrode, or combinations thereof.

16. The membraneless electrolyzer system according to claim 10, further comprising a recycle stream in fluid communication with the product outlet and the first reactant inlet.

17. The membraneless electrolyzer system according to claim 10, wherein the liquidphase reactants include one or more alkenes, the gas-phase reactants include oxygen, and the product outlet is in fluid communication with a product stream including concentrations of H2O2, epoxidized alkenes, or combinations thereof.

18. The membraneless electrolyzer system according to claim 10, further comprising one or more porous manifolds configured to radially distribute within the electrolyzer body reactant from the first reactant inlet, the second reactant inlet, or combinations thereof.

19. A membraneless electrolyzer system comprising: a source of gas-phase reactants; a source of liquid phase-reactants; an electrolyzer including: an electrolyzer body having a first end, a second end, a longitudinal dimension extending from the first end to the second end, and a radial dimension; a liquid-phase reactant inlet proximate the first end; at least one gas-phase inlet positioned proximate the second end; a product outlet proximate the second end;1832570368.1Atorney Docket No.: 105041-201 at least two separator-electrode assemblies (SEA) positioned between the first reactant inlet and the product outlet and arranged serially, the SEA including: a cathode; an anode; a separator positioned between the cathode and the anode, wherein the cathode, the separator, and the anode are arranged serially along the longitudinal dimension from the first end to the second end, at least one porous manifold configured to distribute in the radial dimension liquid-phase reactant, gas-phase reactant, or combinations thereof, a source of EE in fluid communication with the at least one gas-phase inlet; and a source of carbon dioxide in fluid communication with the liquid-phase reactant inlet, gas-phase inlet, or combinations thereof.

20. The membraneless electrolyzer system according to claim 19, further comprising a plurality of flow-through channels from a surface of the cathode to a surface of the anode.1932570368.1

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