Electrochemical generation of carbon-containing products from carbon monoxide

Abstract

Disclosed herein is a method method of forming one or more carbon-containing products by electroreduction of carbon monoxide in a flow electrolyzer comprising a working electrode and a counter electrode separated by a non-ionic porous membrane.

Description

ELECTROCHEMICAL GENERATION OF CARBON-CONTAINING PRODUCTS FROM CARBON MONOXIDESTATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0001] This invention was made with government support under DE-AR0001244 awarded by the Department of Energy. The government has certain rights in the invention.BACKGROUND OF THE INVENTION

[0002] This invention relates to the field of electrochemical conversion of carbon monoxide (CO) for production of chemicals.

[0003] US 11959184 generally discloses the conversion of carbon monoxide and carbon dioxide (CO2) to various chemical products in an electrochemical cell by electrocatalyzing carbon monoxide or carbon dioxide in the presence of one or more nucleophilic co-reactants in contact with a catalytically active material present on the working electrode, thereby forming one or more carbon-containing products electrocatalytically.

[0004] The electrochemical cell in US 11959184 has a working electrode and counter electrode separated by a porous polar membrane (anion exchange membrane, cation exchange membrane or bipolar membrane). Anion exchange membranes are said to be preferred, and listed suitable examples include FAA membranes, quaternary amine alkaline anion exchange membranes, and Sustainion® imidazolium-functionalized polymer membranes.

[0005] In an ion exchange membrane, ion conduction is controlled by the membrane structure, and the structure dominates resistive contributions to the cell operating voltage in the flow electrolyzer. Free transfer of soluble and liquid products is often constrained by a need to maximize ion conduction.

[0006] One additional disadvantage to the use of ion exchange membranes is that such membranes must be pre-conditioned prior to assembly of the electrochemical cell, which can be complicated and time-consuming, and brings an undesired potential inconsistency to the construction and operation of the electrochemical cell.LECT1002WO PCT ApplicationSUMMARY OF THE INVENTION

[0007] It has now been found that, in certain systems, the electrochemical conversion of carbon monoxide to various carbon-containing products can be effectively and advantageously performed using a specific type of non-polar membrane disposed between the working electrode and counter electrode.

[0008] In accordance with the present invention there is provided a method of forming one or more carbon-containing products by electroreduction of carbon monoxide in a flow electrolyzer comprising a working electrode and a counter electrode separated by a porous membrane, comprising steps of:

[0009] streaming a stream of carbon monoxide into the flow electrolyzer, and

[0010] electrocatalyzing carbon monoxide from said stream in the presence of one or more nucleophilic co-reactants in contact with a catalytically active material present on the working electrode thereby forming one or more carbon-containing products electrocatalytically,

[0011] wherein the porous membrane is a non-ionic porous membrane having a nominal pore size of from about 0.01 pm to about 5.0 pm, and a bubble point of about 1 psi or greater.

[0012] In one embodiment, the non-ionic porous membrane has an average pore size in the range of from about 0.01 pm to about 10 pm.

[0013] In one embodiment, the non-ionic porous membrane has a thickness of from about 10 pm to about 600 pm.

[0014] The non-ionic porous membrane should be of a material that is chemically resistant to the reactants used in the method.

[0015] In one embodiment, the non-ionic porous membrane is made from a material selected from the group consisting of polytetrafluoroethylene, polyethersulfone, polyvinylidene (di)fluoride, nylon and glass fiber.

[0016] In one embodiment, the stream of carbon monoxide consists essentially of carbon monoxide.

[0017] With the use of a non-polar (non-ionic) membrane in accordance with the present invention, ion conduction is controlled by the liquid electrolyte saturating the separator, gasLECT1002WO PCT Application crossover is prevented at differential pressures below the bubble point, and the electrolyte properties dominate resistive contributions to the cell operating voltage in the flow electrolyzer. Together, these effects lower the transport resistance for liquid and soluble carbon-containing products, and typically decrease cell overpotential compared to ion conducting membranes of the same thickness.

[0018] In addition, the use of non-polar membranes advantageously do not require preconditioning prior to assembly of the electrochemical cell, and only require wetting just prior to use. The wetting may be achieved by flowing liquid electrolyte just before applying power to the electrochemical cell.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention, and together with the written description, serve to explain certain principles of the invention.

[0020] FIGURE 1A shows a schematic illustration of a three-compartment CO flow electrolyzer.

[0021] FIGURE IB shows a schematic illustration of a two-compartment CO flow electrolyzer.

[0022] FIGURE 1C shows a schematic illustration of another two-compartment CO flow electrolyzer.

[0023] FIGURE ID shows a schematic illustration of another two-compartment CO flow electrolyzer.

[0024] FIGURE 2 is a flow chart of the method of electroreduction in accordance with various embodiments of the present invention.

[0025] FIGURE 3 is a graph of the overall cell voltage and product distributions from Example 1.

[0026] FIGURE 4 is a graph of the voltage profile and total faradaic efficiencies from Example 2.LECT1002WO PCT ApplicationDETAILED DESCRIPTION|0027| In the context of the present description, all publications, patent applications, patents and other references mentioned herein, if not otherwise indicated, are explicitly incorporated by reference herein in their entirety for all purposes as if fully set forth. Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that prior art forms part of the common general knowledge in the field of endeavor in any country in the world.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to whom this disclosure pertains. In case of conflict, the present specification, including definitions, will control.

[0029] Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.

[0030] When an amount, concentration, or other value or parameter is given as a range, or a list of upper and lower values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper and lower range limits, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, as well as all integers and fractions within the range. It is not intended that the scope of the present disclosure be limited to the specific values recited when defining a range. As an example, a stated range of 1-10 fully describes and includes the independent subrange 3.4 - 7.2.

[0031] When the term “about” is used, it is used to mean a certain effect or result can be obtained within a certain tolerance, and the skilled person knows how to obtain the tolerance. When the term "about" is used in describing a value or an endpoint of a range, the disclosure should be understood to include the specific value or endpoint referred to.

[0032] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," “contains,” “containing,” or any other variation thereof, are intended to cover a nonexclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0033] The transitional phrase "consisting of' excludes any element, step, or ingredient not specified in the claim, closing the claim to the inclusion of materials other than those recitedLECT1002WO PCT Application except for impurities ordinarily associated therewith. When the phrase "consists of' appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0034] The transitional phrase "consisting essentially of' limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. A ’‘consisting essentially of’ claim occupies a middle ground between closed claims that are written in a “consisting of’ format and fully open claims that are drafted in a “comprising” format. Optional additives as defined herein, at a level that is appropriate for such additives, and minor impurities, are not excluded from an embodiment by the term “consisting essentially of’ unless they materially affect the basic and novel characteristic(s) of the embodiment in question.

[0035] Further, unless expressly stated to the contrary, "or" and “and / or” refers to an inclusive and not to an exclusive. For example, a condition A or B, or A and / or B, is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0036] The use of "a" or "an" to describe the various elements and components herein is merely for convenience and to give a general sense of the disclosure. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0037] The term “predominant portion” or “predominantly”, as used herein, unless otherw ise defined herein, means greater than 50% of the referenced material. If not specified, the percent is on a molar basis when reference is made to a molecule (such as hydrogen and ethylene), and otherwise is on a weight basis (such as for solids or additive content).

[0038] The term “substantial portion” or “substantially”, as used herein, unless otherwise defined, means all or almost all or the vast majority, as would be understood by the person of ordinary skill in the context used. It is intended to take into account some reasonable variance from 100% that would ordinarily occur in industrial-scale or commercial-scale situations.

[0039] The term “bubble point” means the minimum pressure necessary' to pass an air bubble through a porous material saturated with liquid, and is measured according to ASTM F316-03LECT1002WO PCT Application(Reapproved 2019). The bubble point is a function of maximum pore size, in the absence of any damage or system leaks that would compromise the measurement.

[0040] The term "‘nominal pore size” means the filter rating as generally obtained from manufacturer’s literature. For example, a filter with a nominal pore size of 0.22 pm means that such filter is rated to retain particles having a diameter of 0.22 pm and larger.

[0041] The term “average pore size” means the mean flow pore size, and is measured according to ASTM F316-03 (Reapproved 2019).

[0042] A more complete understanding of the present invention will be provided in relation to the following examples which are understood to be non-limiting to the basic inventive concepts of the present invention.

[0043] In an aspect, a method of electroreduction with a working electrode and counter electrode is provided. The method generally comprises electrocatalyzing carbon monoxide in the presence of one or more nucleophilic co-reactants in contact with a catalytically active material present on the working electrode, wherein a specified non-ionic porous membrane separates the working electrode from the counter electrode, thereby forming one or more carbon-containing products electrocatalytically.

[0044] In an embodiment, the counter electrode is an anode including an anodic catalytically active material. The anode is comprised of at least one metal selected from the group consisting of iridium, nickel, iron and tin. Additionally, the at least one metal may be present, at least in part, as a metal oxide. Suitable examples of anode materials may include, but are not limited to Ir / IrO2, NiO, CO3O4, Fe-NiOx, RuCT, MnCh, fr^Ch, and Co-POx.

[0045] In another embodiment, the anode is “metal-free.” As used herein, the term “metal- free” refers to an anodic catalytically active material which does not contain an active metal component. Suitable examples of “metal-free” anodes include, but are not limited to, conductive carbon, graphitic carbon, graphene, and functionalized graphene-based materials.

[0046] In one embodiment, the anode comprises a layer of anodic catalytically active material on at least one side of a support. In yet another embodiment, the layer of anodic catalytically active material is formed of particles, such as nanoparticles, microparticles or a mixture thereof to tune the porosity of the anode. The particle size can be in the range of from about 1 nm to about 10 pm. In a further embodiment, the particles of the layer of anodic catalytically activeLECT1002WO PCT Application material may be dispersed in or on a gas diffusion layer optionally in the presence of an ion conducting polymer or a hydrophobic polymer. The anodic catalytically active material may be present in any suitable amount in the anode, such as in an amount ranging from about 0.01 mg / cm2to about 100 mg / cm2, for example, from about 0.01 mg / cm2to about 1 mg / cm2, or from about 1 mg / cm2to about 10 mg / cm2, or from about 10 mg / cm2to about 100 mg / cm2. In one embodiment, the mass per geometric area is measured as the amount of catalyst on top of a substrate of arbitrary thickness.

[0047] Any suitable gas diffusion layer material may be used, including but not limited to carbon paper, carbon fibers, carbon cloth, porous graphene, metal mesh and metal foam with or without surface coatings.

[0048] Suitable examples of ion conducting polymers include, but are not limited to, anion conducting polymers, cation conducting polymers, and bipolar polymers.

[0049] Suitable examples of hy drophobic poly mers include, but are not limited to, ion conducting ionomers, Teflon®, and polytetrafluoroethylene (PTFE).

[0050] When used, the gas diffusion layer should be sufficiently porous so as to allow sufficient transport of reactant and product gas to and from the catalyst material. Desirably, the gas diffusion layer further limits transport of liquids (usually water and usually through the action of hydrophobic polymers).

[0051] In an embodiment, the working electrode is a cathode comprising a cathodic catalytically active material comprised of at least one of copper, copper oxide, or a copper containing material. In one embodiment, the cathode comprises a layer of cathodic catalytically active material on at least one side of a support. In yet another embodiment, the layer of anodic catalytically active material is formed of particles, such as nanoparticles, microparticles or a mixture thereof to tune the porosity of the cathode. The particle size can be in the range of from about 1 nm to about 20 pm, for example, from about 1 nm to about 0.5 pm, or from about 0.5 pm to about 1.5 pm, or from about 2 pm to about 20 pm. In a further embodiment, the particles of the layer of cathodic catalytically active material may be dispersed in or on a gas diffusion layer such as an ion conducting polymer or a hydrophobic polymer. The cathodic catalytically active material may be present in any suitable amount in the cathode, such as in an amount of from about 0.01 mg / cm2to about 100 mg / cm2, or from about 0.01 mg / cm2to about 1 mg / cm2, or from about 1 mg / cm2to about 10 mg / cm2, or from about 10 mg / cm2to about 100 mg / cm2.LECT1002WO PCT Application

[0052] In an embodiment, the cathodic catalytically active material is an “oxide-derived copper” (hereinafter referred to as “OD-Cu”). OD-Cu can be prepared by annealing micron size copper particles at a temperature in the range of from about 100°C to about 1100°C, for any suitable amount of time, such as at about 500°C for 2 hours. During annealing, copper particles undergo a change in morphology from spherical particles to irregular shapeds, sizes, and also phase transition from cubic metallic Cu to monoclinic CuO. The resulting CuO particles can then be dispersed in a catalyst ink with multi-walled carbon nanotubes present in an amount of from about 0.01 to about 10 mg per mg of Cu, and then a layer of cathodic catalytically active material can be formed onto a gas-diffusion layer (GDL) using any suitable method such as drop-cast, spraying, or wet-impregnation. The cathode can then be preconditioned through an in-situ electrochemical reduction at a constant current density of from about 1 to about 200 mA / cm2After the pre-conditioning, the OD-Cu sample becomes highly porous with a pore size of from about 10 nm to about 20 nm.

[0053] Any suitable catalyst ink can be used, including, but not limited to, a mixture of solvents, catalyst particles, polymers, and binders.

[0054] In another embodiment, the cathodic catalytically active material is present on a carbon support or a conductive support which is dispersed in an ion conducting polymer or a hydrophobic polymer and deposited on a porous gas diffusion layer or porous membrane material.

[0055] Referring back to the method of electroreduction, any suitable nucleophilic co-reactant may be used. The one or more nucleophilic co-reactants may be selected from the group consisting of ammonia, amines, water, alcohols, carboxylic acids and thiols. The nucleophilic co-reactant may comprise one or more nucleophilic functional groups per molecule bearing at least one active hydrogen, wherein the functional group(s) may be selected from hydroxyl (- OH), thiol (-SH), carboxyl (-CO2H), or primary or secondary amino (-NHR, wherein R is H or an organic group). The nucleophilic co-reactant may comprise no carbon atoms (as in the case of water and ammonia) or one or more carbon atoms. In one embodiment, the one or more nucleophilic co-reactants are selected from the group consisting of C1-C6 aliphatic primary amines, C1-C6 aliphatic secondary amines, aromatic primary amines, and aromatic secondary amines. Exemplary nucleophilic co-reactants include, but are not limited to, ammonia, methylamine, ethylamine, dimethylamine, water, glycine, ethanol amine, and hydroxide.LECT1002WO PCT Application

[0056] The one or more nucleophilic co-reactants may be used in any suitable amount. In one embodiment, the ratio of carbon monoxide and the one or more nucleophilic co-reactants is in the range of from about 0.01 to about 100 or from about 100 to about 0.01 (mol / mol ratio). In a specific embodiment, the ratio of NH3 to CO is about 2: 1 (mol / mol ratio).

[0057] According to embodiments of the present invention, the one or more carbon-containing products may comprise one or more carbon-containing products selected from the group consisting of ethylene, carboxylic acids (e.g., acetic acid), aldehydes (e.g., acetaldehyde), alcohols (e.g., ethanol, propanol), amides, and thioesters. In certain embodiments, the carbon- containing products may be multi-functional (i.e., they may contain two or more different types of functional groups, such as both an amide functional group and a hydroxyl functional group or both an amide functional group and a carboxylic acid functional group). Generally speaking, the one or more carbon-containing products include one or more products which contain an additional carbon as compared to the number of carbons in the nucleophilic co-reactant(s), wherein the additional carbon is derived from the carbon monoxide reacted with the nucleophilic co-reactant(s).

[0058] The electroreduction further utilizes an electrolyte. In certain embodiments, both an anolyte and a catholyte are employed. In other embodiments, only an anolyte is employed. The anolyte and the catholyte may be the same as, or different from, each other. Any substance which provides ionic conductivity when dissolved in a suitable medium may be employed. The electrolyte, anolyte and / or catholyte are preferably dissolved in a liquid medium, such as water or a non-aqueous liquid solvent. Any of the electrolytes know n in the art may be utilized, including for example metal salts comprising at least one metal cation (such as an alkali metal cation, e.g., sodium, potassium) and at least one anion selected from the group consisting of carbonate, bicarbonate, halides (e.g., chloride, iodide), and hydroxide. The choice of electrolyte has a significant impact on the selectivity of catalyst in electrochemical carbon monoxide and carbon dioxide reduction.

[0059] In an aspect, the method further comprises using an anolyte and an optional catholyte, wherein the anolyte comprises at least one metal cation and wherein the catholyte comprises at least one of carbonate, bicarbonate, chloride, iodide, hydroxide or other anion.

[0060] In an embodiment, the method further comprises streaming the anolyte through an anolyte chamber, carbon monoxide through a fluid chamber and optionally a catholyte through an optional catholyte chamber of an electrolyzer, and streaming one or more nucleophilic co-LECT1002WO PCT Application reactants with the anolyte, carbon monoxide or the optional catholyte. The method also comprises electrically connecting the anode and the cathode using a source of electrical current and electrocatalyzing carbon monoxide in the presence of the one or more nucleophilic coreactants in contact with a catalytically active material present on the working electrode, thereby forming one or more carbon-containing chemical products electrocatalytically.

[0061] In accordance with the present invention, the working electrode and counter electrode are separated by a non-ionic porous membrane.

[0062] The non-ionic porous membrane should have a nominal pore size of from about 0.01 pm, or from about 0.1 pm, or from about 0.22 pm, to about 5.0 pm, or to about 0.45 pm, and a bubble point of about 1 psi or greater, or from about 1 psi, or from about 22 psi, to about 50 psi, or to about 45 psi.

[0063] Desirably, the pore size selection provides an optimal balance between high bubble point (higher gas isolation between chambers) and fast liquid transport (lower energy use at high applied current density).

[0064] Preferred examples include hydrophilic and hydrophobic polytetrafluoroethylene (PTFE), polyethersulfone (PES), hydrophilic and hydrophobic polyvinylidene (di)fluoride (PVDF), nylon, and glass fiber. Particularly preferred are PES and hydrophobic PVDF.

[0065] In an embodiment, the non-ionic porous membrane comprises a porous material with surface functional groups that increase hydrophobicity (as compared to the material without such surface functional groups).

[0066] In an embodiment, the non-ionic porous membrane comprises a porous material with surface functional groups that increase hydrophilicity (as compared to the material without such surface functional groups).

[0067] In an embodiment, the average pore size of the porous separator ranges from about 0.01 pm, or 0.1 pm, to about 10 pm, or to about 0.45 pm. Desirably, the average is as close as possible to the maximum pore size, or slightly lower.

[0068] In an embodiment, the porous separator comprises a material with a thickness of from about 10 pm, or about 40 pm, to about 600 pm, or about 100 pm. ioLECT1002WO PCT Application

[0069] Prior to electroreduction, the non-ionic porous membrane needs to be saturated with a liquid. Any liquid or dissolved species can saturate the separator and cross to the other side. The maximum rate of crossover within the membrane is driven by differential pressure and is a function of pore size, while the actual rate of crossover is further restricted by hydrophobic coatings in the catalyst layer or gas diffusion layer. In the absence of liquid saturation, gases can pass through the separator. Liquid saturation prevents transport of non-dissolved gases below the bubble point, which represents a pressure threshold and operational limit for devices using this type of material in various embodiments.

[0070] Since the separator materials are not involved in ion conduction and do not participate in the electrochemical reactions, the main properties of consequence are as follows:

[0071] Pore size: governs the bubble point and resistance to through-plane and in-plane liquid flow.

[0072] Thickness: governs resistance to through-plane liquid flow.

[0073] Material: governs stability. Suitable materials must resist attack from carbon monoxide, any generated products, and the electrolyte. For example, glass fiber might be susceptible in a strongly alkaline environment, and should not be used in those conditions. Chemical stability of the various materials is in general known to those of ordinary skill in the relevant art, and can usually be found by referencing material data sheets and other information generally available from the membrane manufacturer.

[0074] All three of these properties also contribute to the operating cell voltage.

[0075] Generally, there are no special assembly instructions and carbon monoxide electroreduction devices may be assembled in normal fashion. If the cell is assembled dry, however, liquid must be allowed to saturate the separator prior to operation.

[0076] In an embodiment, the porous non-ionic membrane and the operating conditions are selected so that the difference in pressure between the fluid chamber and the anolyte chamber ranges from 0 psi, or from about 5 psi. or from about 10 psi. to about 50 psi, or to about 40 psi, or about 30 psi, or about 25 psi.

[0077] In an embodiment, the difference in pressure betw een the fluid chamber and the anolyte chamber is controlled to stay below' the intrinsic bubble point of the non-ionic porous membrane during dynamic operation.LECT1002WO PCT Application

[0078] A more specific method of electroreduction in accordance with the present invention is shown in Figure 2, and comprises the steps of streaming an anolyte through an anolyte chamber, carbon monoxide through a fluid chamber and optionally a catholyte through an optional catholyte chamber of an electrolyzer. The method also includes streaming one or more nucleophilic co-reactants with the anolyte, carbon monoxide or the optional catholyte. The method further includes electrically connecting the anode and the cathode using a source of electrical current and electrolyzing carbon monoxide in the presence of the one or more nucleophilic co-reactants in contact with a catalytically active material present on a working electrode, thereby forming one or more carbon-containing chemical products electrocatalytically.

[0079] In a more specific aspect of the invention, the method of electroreduction uses a three- compartment electrolyzer 100 as shown in Figure 1A. The electrolyzer 100 comprises an anolyte chamber 121 disposed in between an anode 112 and anon-ionic porous membrane 114, a fluid chamber 122 disposed on a side of the cathode 116 opposite the non-ionic porous membrane 114, a catholyte chamber 123 disposed in between a cathode 116 and the non-ionic porous membrane 114, and a source of electrical current 132 for electrically connecting the anode 112 and the cathode 116.

[0080] The method of electroreduction using the three-compartment electrolyzer 100 comprises streaming the anolyte 101 through the anolyte chamber 121 and streaming carbon monoxide through the fluid chamber 122. The method also comprises streaming the catholyte 102 through the catholyte chamber 123 and streaming the one or more nucleophilic co-reactants 104 through at least one of the anolyte chamber 121, the fluid chamber 122, or the catholyte chamber 123. The method further comprises electrically connecting the anode 112 and the cathode 116 using a source 132 of electrical current and electrocatalyzing the carbon monoxide in the presence of the one or more nucleophilic co-reactants in contact with the cathodic catalytically active material present in the cathode 116, thereby forming carbon-containing products 142 electrocatalytically.

[0081] In another more specific aspect of the invention, the method of electroreduction uses a three-compartment electrolyzer 200 as shown in Figure IB. The electrolyzer 200 comprises an anode 212 disposed in contact with a non-ionic porous membrane 214, an anolyte chamber 221 disposed on a side of the anode 212 opposite the non-ionic porous membrane 214, a catholyte chamber 223 disposed in between the non-ionic porous membrane 214 and a cathode 216, andLECT1002WO PCT Application a fluid chamber 122 disposed on a side of the cathode 216 opposite the non-ionic porous membrane 214; and a source of electrical current 232 for electrically connecting the anode 212 and the cathode 216.

[0082] The method of electroreduction using an electrolyzer 200, as shown in Figure IB, comprises streaming the anolyte 201 through the anolyte chamber 221, streaming carbon monoxide 202 through the fluid chamber 222 and streaming the one or more nucleophilic coreactants 204 through at least one of the anolyte chamber 221, the fluid chamber 222, or the catholyte chamber 223. The method also comprises electrically connecting the anode 212 and the porous cathode 216 using a source 232 of electrical current and electrocatalyzing the carbon monoxide in the presence of the one or more nucleophilic co-reactants in contact with the cathodic catalytically active material present in the cathode 216, thereby forming carbon- containing products 242 electrocatalytically.

[0083] In yet another more specific aspect of the invention, the method of electroreduction comprises using a two-compartment electrolyzer 300 as shown in Figure 1C. The two- compartment electrolyzer 300 comprises an anolyte chamber 321 disposed in between an anode 312 and a non-ionic porous membrane 314 and a cathode 316 disposed in contact with the nonionic porous membrane 314 on a side opposite the anolyte chamber 321. The electrolyzer 300 also comprises a fluid chamber 322 disposed on a side of the cathode 316 opposite the non- ionic porous membrane 314 and a source of electrical current 332 for electrically connecting the anode 312 and the porous cathode 314.

[0084] The method of electroreduction using the tw o-compartment electrolyzer 300, as shown in Figure 1C, comprises streaming the anolyte 301 through the anolyte chamber 321, streaming carbon monoxide 302 through the fluid chamber 322, and streaming the one or more nucleophilic co-reactants through the anolyte chamber 321 or the fluid chamber 322. The method further comprises electrically connecting the anode 312 and the cathode 316 using a source 332 of electrical current and electrocatalyzing the carbon monoxide in the presence of the one or more nucleophilic co-reactants in contact with the cathodic catalytically active material present in the cathode 316, thereby forming carbon-containing products 342 electrocatalytically. In an embodiment, the nucleophilic co-reactant is water and the carbon- containing product 342 comprises an acetate salt.

[0085] In yet another more specific aspect of the invention, the method of electroreduction comprises using a two-compartment electrolyzer 400 as shown in Figure ID. The two-LECT1002WO PCT Application compartment electrolyzer 400 comprises a non-ionic porous membrane 314 sandwiched in between and in contact with an anode 412 on one side and a cathode 416 on the other side. The electrolyzer 400 also comprises an anolyte chamber 421 disposed on a side of the anode 412 opposite the non-ionic porous membrane 414. The electrolyzer 400 also comprises a fluid chamber 422 disposed on a side of the cathode 416 opposite the non-ionic porous membrane 414 and a source of electrical current 432 for electrically connecting the anode 412 and the cathode 414.

[0086] The method of electroreduction using the two-compartment electrolyzer 400, as shown in Figure ID, comprises streaming the anolyte 401 through the anolyte chamber 421 , streaming carbon monoxide 402 through the fluid chamber 422, and streaming the one or more nucleophilic co-reactants through the anolyte chamber 421 or the fluid chamber 422. The method further comprises electrically connecting the porous anode 412 and the porous cathode 416 using a source 432 of electrical current and electrocatalyzing the carbon monoxide in the presence of the one or more nucleophilic co-reactants in contact with the cathodic catalytically active material present in the cathode 416, thereby forming carbon-containing products 442 electrocatalytically.

[0087] In a more specific embodiment, the method of electroreduction uses the two- compartment electrolyzer 400, as shown in Figure ID with water as the nucleophilic coreactant, thereby resulting in the production of acetic acid (or an acetate salt) as the carbon- containing product 442. In contrast, if another electrolyzer such as those shown in Figures 1 A- 1C is used with water as the nucleophilic co-reactant, then acetic acid may be produced under suitable pH conditions.

[0088] In an embodiment, the method of producing a carbon-containing product is conducted under basic conditions with a pH in the range of from about 8 to about 15.

[0089] In an embodiment, the method of producing a carbon-containing product is conducted under acidic conditions with a pH in the range of 0 to about 6.

[0090] In an embodiment, the method of producing a carbon-containing product is conducted under substantially neutral conditions with pH in the range of about 6 to about 8.

[0091] In an embodiment, the temperature of the system is maintained between about -10°C and about 90°C.LECT1002WO PCT Application

[0092] In an embodiment, exemplary nucleophilic co-reactants used in any of the electrolyzers shown in Figures 1A-1D include, but are not limited to, ammonia, methylamine, ethylamine, dimethylamine, glycine, ethanol amine, and hydroxide and the resulting carbon-containing products include, but are not limited to, amide, acetamide, N-methylacetamide, N- ethylacetamide, N,N-dimethylacetamide, aceturic acid or the corresponding salt, acetic monoethanolamide, and acetic acid or the corresponding salt.

[0093] In a specific embodiment, the method comprises the steps of:

[0094] (A) providing the flow electrolyzer which comprises (i) the anode having a first anode side and a second anode side, (ii) the cathode having a first cathode side and a second cathode side, (iii) the porous membrane between the first anode side and the second cathode side having a first membrane side and a second membrane side, (iv) the first fluid chamber in contact with the first cathode side, (v) the anolyte chamber in contact with the first anode side, or the second anode side, or both the first anode side and the second membrane side, and (vi) the optional catholyte chamber in contact with the second cathode side, or in contact with both the second cathode side and the first membrane side,

[0095] (B) providing an electricity source, wherein the anode and cathode are electrically connected to the electricity source;

[0096] (C) providing the carbon monoxide stream;

[0097] (D) providing the anolyte stream comprising a first electrolyte;

[0098] (E) optionally providing the catholyte stream comprising a second electrolyte;

[0099] (F) providing the nucleophilic co-reactant stream comprising one or more nucleophilic co-reactants;

[0100] (G) concurrently flowing the carbon monoxide stream into the first fluid chamber, the anolyte stream into the anolyte chamber, optionally the catholyte stream if present into the catholyte chamber if present, and the nucleophilic co-reactant stream into either (i) the first fluid chamber or the anolyte chamber, or (ii) if the catholyte chamber is present, the first fluid chamber, the anolyte chamber or the catholyte chamber;

[0101] (H) providing an electric current from the electricity source through the anode to the cathode to generate the carbon-containing product; andLECT1002WO PCT Application

[0102] (I) withdrawing a stream of the carbon-containing product from the flow electrolyzer.

[0103] In an embodiment, all of the in-streaming components - the anolyte, catholyte, carbon monoxide and one or more nucleophilic co-reactants - have the same directional flow and the out-streaming carbon-containing products have the same directional flow.

[0104] In another embodiment, the in-streaming components - the anolyte, catholyte, carbon monoxide and one or more nucleophilic co-reactants - have a directional flow opposite to the rest of the in-streaming components and the out-streaming components such as carbon- containing products have a directional flow opposite to the other out-streaming components.

[0105] In yet another embodiment, at least one of the in-streaming components - the anolyte, catholyte, carbon monoxide and one or more nucleophilic co-reactants - have a directional flow at an angle to the rest of the in-streaming components and the out-streaming components such as carbon-containing products have a directional flow opposite to the other out-streaming components.

[0106] In some embodiments, the in-streaming of the components - the anolyte, catholyte, carbon monoxide and one or more nucleophilic co-reactants - is done in a steady continuous flow. In an embodiment, the flow rate of the anolyte, catholyte, carbon monoxide and one or more nucleophilic co-reactants is in the range of 0.01-100 rnL / min per cm2of electrode.

[0107] The electrocatalytic production of carbon-containing products in accordance with the present disclosure has a Faradaic efficiency of at least 1% at a current density in the range of 0.1-3000 mA / cm2or 0.1-100 mA / cm2or 100-1000 mA / cm2or 1000-3000 mA / cm2. Faradaic efficiency refers to the fraction of electrons allocated to a particular product compared to the total electrons transferred (to products + losses).

[0108] The electrocatalytic production of carbon-containing products in accordance with the present disclosure has a C21 selectivity of at least 1% or at least 10% or at least 70%, wherein the C2+ selectivity is calculated as the total number of electrons transferred to C2+ product(s) divided by the total number of electrons passed through the electrode.

[0109] Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.LECT1002WO PCT ApplicationEXAMPLES

[0110] Examples of the present invention will now be described. The technical scope of the present invention is not limited to the examples described below.

[0111] Example 1

[0112] In one example, CO electrolysis was conducted in a two-chamber flow electrolyzer similar to the configuration as shown in Figure ID employing a series of nylon porous membranes with nominal pore sizes ranging from about 0.22 pm to about 0.45 pm and with a thickness of approximately 100 pm. A copper nanoparticle catalyst w as deposited on Sigracet 39BB carbon fiber paper with aNafion ionomer in the ink formulation as the cathode, while a custom-prepared NiFeOOH anode deposited on porous Ni foam was used as the anode. Gas pressure was maintained between 3 and 6 psi while flowing CO reactant gas in the cathode first fluid chamber — adjusted as needed with a downstream backpressure regulator to stay below7the bubble point of the nylon material — and a stream of IM potassium hydroxide in water as the first electrolyte. During operation, I00mA / cm2current density was applied between the cathode and anode. Gas products were analyzed using inline gas chromatography, while liquid products were periodically collected and analyze using a quantitative NMR-based procedure.

[0113] For this series of CO electrolysis tests, the overall cell voltage and product distributions were tracked over one hour as shown in Figure 3. Production of acetate was generally highest when using nylon with the smallest pore size, though multiple experimental factors may contribute to the relatively small observed differences. That higher acetate production also corresponded to higher hydrogen production but nearly identical total gas phase faradaic efficiency, which may point to better preservation of highly alkaline conditions close to the cathode due to slower bulk transport. Regardless, there was no evidence of gas crossover during the electrochemical experiments. After testing the nylon with 3.0 pm material, the pressure w as increased above 6 psi to verify that free flow of gas through the nylon and into the anode chamber could still occur after the bubble point w as exceeded.

[0114] Example 2

[0115] In another example, CO electrolysis was conducted in a two-chamber flow electrolyzer with the same parameters and measurement techniques as the previous example, except employing a polyethersulfone-based porous membrane with a 0.22 pm average pore size and 100 pm approximate thickness. The voltage profile and total faradaic efficienciesLECT1002WO PCT Application towards multi-carbon products are shown in Figure 4. After an initial decrease in total faradaic efficiency and slight increase in cell voltage, the production characteristics stabilized over a 300-hour demonstration period. As in the previous example, there was no evidence of gas crossover between the cathode and anode fluid chambers, indicating that the bubble point effect preserves gas separation between the chambers while allowing transport of liquids and dissolved products.

[0116] In summary', the present disclosure provides a new route to produce a variety of carbon-containing products generated through CO electrolysis in the presence of nucleophilic co-reactants through incorporation of a non-ionic porous membrane separator, including but not limited to, forming amides through co-reaction with amines, and acetate or acetic acid through co-reaction with hydroxide or water. Particularly, N,N-dimethylacetamide has significant usage as a polymerization solvent, and currently requires harsh synthesis conditions. More importantly, the concept of nucleophilic attack of ketene intermediate in Cu-catalyzed CO electroreduction enables the formation of a much wider range of chemicals containing not only C-C bonds but also carbon-heteroatom bonds, which cannot be built in conventional CO electrolysis processes. The ability to produce heteroatom containing carbon species would greatly increase the potential of CO2 / CO electrolysis technologies for commercial applications.

[0117] While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.

Claims

LECT1002WO PCT ApplicationWhat is Claimed is:

1. A method of forming one or more carbon-containing products by electroreduction of carbon monoxide in a flow electrolyzer comprising a working electrode and a counter electrode separated by a porous membrane, comprising steps of:(a) streaming a stream of carbon monoxide into the flow electrolyzer, and(b) electrocatalyzing carbon monoxide from said stream in the presence of one or more nucleophilic co-reactants in contact with a catalytically active material present on the working electrode thereby forming one or more carbon-containing products electrocatalytically, characterized in that the porous membrane is a non-ionic porous membrane having a nominal pore size of from 0.01 pm to 5.0 pm, and a bubble point of 1 psi or greater.

2. The method of claim 1, characterized in that the nominal pore size is from 0. 1 pm, or from 0.22 pm, to 5.0 pm, or to 0.45 pm, or from 0.01 pm to 0.45 pm.

3. The method of claim 1 or claim 2. characterized in that the bubble point is from 1 psi, or from 22 psi, to 50 psi, or to 45 psi.

4. The method of any one of claims 1-3, characterized in that the non-ionic porous membrane has an average pore size in the range of from 0.01 pm, or 0.1 pm, to 10 pm, or to 0.45 pm.

5. The method of any one of claims 1-4, characterized in that the non-ionic porous membrane has a thickness of from 10 pm, or 40 pm, to 500 pm, or 100 pm.

6. The method of any one of claims 1-5, characterized in that the non-ionic porous membrane is made of a polymer that is chemically resistant to reactants used in the method.

7. The method of claim 6, characterized in that the non-ionic porous membrane is made from a material selected from the group consisting of polytetrafluoroethylene, polyethersulfone, polyvinylidene (di)fluoride, nylon and glass fiber.

8. The method of any one of claims 1-7, characterized in that the non-ionic porous membrane comprises surface functional groups that increase hydrophobicity.

9. The method of any one of claims 1-7, characterized in that the non-ionic porous membrane comprises surface functional groups that increase hydrophilicity.LECT1002WO PCT Application10. The method of any one of claims 1-9, characterized in that the working electrode is a cathode and the counter electrode is an anode.1 1. The method of claim 10, wherein the working electrode comprises a cathodic catalytically active material comprising at least one of copper or a copper oxide, and / or the counter electrode comprises an anodic catalytically active material selected from the group consisting of iridium, nickel, iron and tin.

12. The method of any one of claims 1-11, characterized in that the one or more nucleophilic co-reactants comprise one or more nucleophilic functional groups per molecule bearing at least one active hydrogen, wherein the functional group(s) are selected from hydroxyl, thiol, carboxyl, primary amino and secondary amino.

13. The method of any one of claims 1-12, characterized in that the flow electrolyzer comprises a fluid chamber, an anolyte chamber and an optional catholyte chamber, and wherein the step of electrocatalyzing comprises the steps of:(bl) streaming an anolyte through the anolyte chamber, the stream of carbon monoxide through the fluid chamber and, optionally, a catholyte through the optional catholyte chamber;(b2) streaming the one or more nucleophilic co-reactants with the anolyte, the stream of carbon monoxide, or if present the optional catholyte;(b3) electrically connecting the anode and the cathode using a source of electrical current, wherein the catalytically active material is present on the cathode, thereby forming the one or more carbon-containing chemical products electrocatalytically.

14. The method of claim 13, comprising the steps of:(A) providing the flow electrolyzer which comprises (i) the anode having a first anode side and a second anode side, (ii) the cathode having a first cathode side and a second cathode side, (iii) the porous membrane between the first anode side and the second cathode side having a first membrane side and a second membrane side, (iv) the first fluid chamber in contact with the first cathode side, (v) the anolyte chamber in contact with the first anode side, or the second anode side, or both the first anode side and the second membrane side, and (vi) the optionalLECT1002WO PCT Application catholyte chamber in contact with the second cathode side, or in contact with both the second cathode side and the first membrane side,(B) providing an electricity source, wherein the anode and cathode are electrically connected to the electricity source;(C) providing the carbon monoxide stream;(D) providing the anolyte stream comprising a first electrolyte;(E) optionally providing the catholyte stream comprising a second electrolyte;(F) providing the nucleophilic co-reactant stream comprising one or more nucleophilic co-reactants;(G) concurrently flowing the carbon monoxide stream into the first fluid chamber, the anolyte stream into the anolyte chamber, optionally the catholyte stream if present into the catholyte chamber if present, and the nucleophilic co-reactant stream into either (i) the first fluid chamber or the anolyte chamber, or (ii) if the catholyte chamber is present, the first fluid chamber, the anolyte chamber or the catholyte chamber;(H) providing an electric current from the electricity source through the anode to the cathode to generate the carbon-containing product; and(I) withdrawing a stream of the carbon-containing product from the flow electrolyzer.

15. The method of any one of claims 1-14, characterized in that the stream of carbon monoxide consists essentially of carbon monoxide.

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