CN116235326A - For direct electrochemical CO 2 Lewis/Bronsted acid/base and nickel phosphide binary catalyst system (cocatalyst) for reduction into hydrocarbon - Google Patents

Abstract

A cathode is disclosed that includes a conductive carrier substrate having an electrocatalyst coating comprising nickel phosphide nanoparticles and a promoter. The electrically conductive carrier substrate is capable of binding a material to be reduced, such as CO ₂ Or CO. Cocatalysts incorporated into the electrolyte solution, or into the conductive support, or adsorbed onto, deposited onto, or incorporated into the host cathode material alter electrocatalyst performance by interacting with the reaction intermediates to increase carbon product selectivity. Also disclosed is the use of water as a hydrogen source from CO ₂ Or an electrochemical process in which CO selectively produces hydrocarbons and/or carbohydrate products.

Description

For direct electrochemical CO 2 Lewis/Bronsted acid/base and nickel phosphide binary catalyst system (cocatalyst) for reduction into hydrocarbon

Cross Reference to Related Applications

The present application claims priority from U.S. non-provisional patent application No. 16/878,165, filed 5/19/2020, which is part continuation-in-process (CIP) of U.S. patent application No. 15/765,896 filed 4/2018, U.S. patent application No. 15/765,896, which is a U.S. national phase entry of international application No. PCT/US16/56026 filed 10/2016, and international application No. PCT/US16/56026 claims priority from 35 u.s.c. 119 (e) to U.S. provisional patent application No. 62/239,389 filed 10/2015, 9/10. All of the above disclosures are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to a novel binary catalyst system combining an acid/base promoter and a nickel phosphide electrocatalyst for the direct electrochemical reduction of carbon dioxide and/or carbon monoxide and/or alpha-hydrogen reactive aldehydes and ketones to hydrocarbons, carbohydrates and other useful products, hereinafter collectively referred to as oxygenated hydrocarbons (or oxygenated hydrocarbons).

Background

Traditional fossil resources are depleted by human activity that contributes carbon dioxide to the atmosphere in ever increasing amounts. This is the most challenge of the current generation-stopping the creation of non-habitable planets. A key component of this challenge is to provide a commercially viable example of sustainable chemical manufacturing, where the waste is fully recycled and the fossil energy is replaced by renewable energy. The present application surrounds these objects. The inherent intermittent nature of most renewable energy sources (e.g., solar and wind) requires energy storage. A safe method of storing large amounts of energy is chemical bonding. Chemical bonds are also necessary to make large amounts of chemicals (raw materials) for making more complex materials. The chemical industry relies on chemical conversion to produce these materials from petroleum, natural gas and coal (fossil resources). Fossil provides a complex and variable mixture of compounds. Future renewable economics must know how to replicate these products. From CO ₂ And the manufacture of complex chemicals for direct water production are one possible solution for the sustainable chemical industry for energy storage and closable carbon circuits. With the recent availability of large amounts of natural gas resources in the united states, a large industrial investment in inexpensive natural gas is growing. Relatively clean waste CO produced by the combustion of natural gas from these industries ₂ The stream can be used as a resource for recovering energy storage and chemical feedstock production. The present application provides a direct method of achieving such recycling.

CO ₂ Electrochemical reduction of (direct CO) ₂ Reduction reaction, DCRR) uses water as a hydrogen source (H ⁺ /e ^- ) Hydrogenation is performed to produce alkanes over Cu and alcohols over noble metals and copper oxides. These techniques cannot have a significant impact due to the following and further limitations: in water with H ₂ Competition for production (by-products) is significant, the high cost of noble metal electrocatalysts, and poor product selectivity that does not yield a single alkane or alkene product when using abundant Cu as the electrocatalyst.

Thus, there is an urgent need for selective, cheaper and more energy efficient DCRR catalysts to produce a variety of useful carbon-based products from carbon dioxide, such as fuels, chemicals and plastics.

Disclosure of Invention

The present invention provides a more efficient and improved two-component catalyst system and method for achieving DCRR.

In the present disclosure, intermediates of all binding surfaces are indicated by asterisks. Based on the above-identified competition problem between hydrogen evolution and DCRR, it is proposed to use the least active hydrogen evolution ₂ Electrocatalysts (e.g. SnO ₂ ) It appears intuitive for DCRR. However, CO is to ₂ And CO reduction to hydrogenation products requires the formation of hydrogen species (×h) bound to the surface. Such hydrogen species may differ in partial charge and include hydrides ( ^δ- ) Atomic hydrogen (×h) and/or partially reduced protons (×h) ^δ+ ) Wherein δ is 0 to 1. These are collectively referred to herein as hydrides. These are the generation of H in water ₂ The same precursor is required. Thus (2)Understanding and controlling the types of surface hydrides and their relative CO with water ₂ The relative reactivity of the/CO and DCRR reaction intermediates is an important factor in achieving selective DCRR electrocatalysts. Previously disclosed for the CO conversion ₂ Transition metal phosphide-based electrocatalysts for electroreduction to hydrocarbons (U.S. patent application Ser. No. 15/765,896) show how such binary compounds can be used as the sole electrocatalyst to control H ₂ With CO ₂ Selectivity between/CO.

It has now been found that the use of the previously disclosed electrocatalysts (based on transition metal phosphides for the conversion of CO ₂ Electroreduction to hydrocarbons; the addition of a different type of catalyst (referred to herein as a co-catalyst) to U.S. patent application Ser. No. 15/765,896 will specifically provide enhanced product selectivity to form a carbon product containing one or more carbon atoms. When used together, the electrocatalyst in combination with the cocatalyst is referred to as a catalyst system. In addition to carbon dioxide and/or carbon monoxide, these also act on the following additives and intermediates: hydrocarbon, aldehyde or ketone type. The promoters claimed in the present invention include all possible additives of binary compounds of nickel and phosphorus, which modify the performance of the catalytic process without consuming itself. The additive may comprise any element or compound that is not a binary compound of nickel and phosphorus (i.e., nickel phosphide), less than 50% by weight of the composition.

The cocatalyst is combined with the reaction intermediate in solution or on the surface: 1) Influencing the binding orientation and binding strength of the intermediate, thereby 2) activating the intermediate for subsequent hydrogenation with the binding surface or with other CO ₂ the/CO or other Cn reaction intermediate, whereby 3) the formation of new reaction intermediates on the surface is promoted, or whereby 4) the desorption of the reaction intermediates is caused, which means that the selectivity for the product is increased.

The combination of promoter and transition metal phosphide catalyst alters the carbon product selectivity while for H alone ₂ Has a small effect on DCRR selectivity. For example, the catalyst system alters the partitioning between the following chemical classes of carbon products: hydrocarbons, carboxylic acids, aldehydes, ketones, ethers, and alcohols (aromatic or aliphatic). The cocatalyst may beTo act on the reaction intermediates or electrocatalysts (catalyst systems) as above to achieve this overall result, without the need for a separate stage or reactor. The promoter may act directly by binding to the electrocatalyst (the so-called "push effect") or to any reaction intermediate that binds to the surface (the so-called "pull effect"). Alternatively, the cocatalysts may act indirectly in solution to alter the reactant or product concentrations, thereby affecting the availability of each activation by the electrocatalyst (transition metal phosphide). In the latter case, these intermediates may or may not be formed on the electrocatalyst alone. The promoter may be immobilized on the electrocatalyst in a subsequent synthesis step, incorporated directly into the support during the electrocatalyst synthesis, or dissolved in an electrolyte solution with the reactants.

The improved product selectivity provided by such catalyst systems enables electrochemical processes for producing purer compounds requiring less processing. For example, ethylene glycol may be derived from CO ₂ Water and renewable electricity production, which would allow green and sustainable polymer production for various markets. Ethylene glycol and related diols are commercially used as monomers in the production of polymers. Similarly, various other feedstocks and monomers may be derived from CO ₂ Preparation, e.g. C ₃ Compounds, methylglyoxal (1, 2-propanediol; MEG), and C of 3-hydroxy-2-furaldehyde and 2-hydroxy-3-furaldehyde ₅ A mixture of compounds which has a possible use as an octane booster in fuels and the like.

One aspect of the invention relates to a combination of: 1) Cathode for the direct electrochemical reduction of carbon dioxide and/or carbon monoxide with/without a carbohydrate comprising an aldehyde or ketone functional group with active alpha-hydrogen (together referred to as feedstock) to an oxygenated hydrocarbon product, said cathode comprising an electrically conductive carrier substrate, a promoter other than nickel phosphide and an electrocatalyst coating comprising Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni (also referred to as "Ni-P") ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ The method comprises the steps of carrying out a first treatment on the surface of the Or said Ni-containing _x P _y The electrocatalyst coating of the nanoparticles of (2) is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ And further with Fe ₂ P alloying, wherein the alloy has about 99:1 to 1:99wt% Ni-P: fe ₂ P ratio; wherein the electrically conductive carrier substrate comprises hydrophobic and hydrophilic regions to facilitate adsorption of the feedstock from a gas or aqueous phase to effect separation from water molecules, wherein at least some of the electrocatalyst nanoparticles are located in the hydrophobic regions of the electrically conductive carrier substrate and catalytically interact with the feedstock by electroreduction to produce oxygenated hydrocarbon products; and 2) wherein the promoter is positioned to function with the electrocatalyst by incorporation into the hydrophilic or hydrophobic regions or by dissolution in the electrolyte or by direct anchoring/incorporation into the catalyst surface.

The cocatalyst can comprise any acid; the acid may be selected from Lewis acids or Bronsted-Loli acids. For example, the acid may be selected from d-region or p-region ions, such as: zn (zinc) ⁺² 、Fe ⁺² 、Fe ³⁺ 、Ca ²⁺ 、Mg ²⁺ 、Al ⁺³ 、AlO ⁺ 、Si ⁴⁺ 、SiO ²⁺ 、H ₃ BO ₃ 、H _x BO _y R _z (wherein x, y and z are each independently 0 or an integer selected from 1 to 3, wherein- (x+ (-2 y) + (z.n)) = -5 or-1 or 0 or 1 or 2 or 3, wherein n is-1, -2 or-3 for the various substitutions on R) such that the boronates include, for example, B (OH) ₂ (OR) and B (OH) (OR) ₂ Wherein r=alkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, wherein the heteroatoms of heteroaryl and heteroarylalkyl are selected from nitrogen, oxygen and sulfur), and mixtures of two or more thereof.

The cocatalyst can comprise any base; the base may be selected from lewis bases or bronsted-lore bases. The base may be selected from each of the above Lewis acids or the aboveConjugate bases of each of the bronsted-lore acids. For example borates, carboxylates, NH ₃ A carboxamide, urea, hydrazine, primary amine, secondary amine, tertiary amine, pyridine and mixtures of two or more thereof.

The cathode may be contacted with an electrolyte solution containing a promoter, or the promoter may be a promoter having HCO ₃ ^- Or CO ₃ ^2- Or H ⁺ An ionic liquid electrolyte that transports the function and is in contact with the cathode. Alternatively, the promoter may comprise modification or doping of the ionomer or conductive polymer or electrode carrier.

Further, the cocatalyst may comprise a salt of Cu, ag, au, zn, a mixture of two or more thereof, or a salt or oxide thereof. Salts or oxides may also become soluble at the appropriate pH. Alternatively, the promoter may comprise a simple metal or alloy selected from Cu, ag, au, zn and intermetallic compounds thereof. The co-catalytic metal or intermetallic compound may be in the form of molecular ions, nanoparticles or larger particles.

Without wishing to be bound by any particular theory, it is believed that the combination of cocatalysts described above bind to a reaction intermediate on the surface of the electrocatalyst, such as, but not limited to, formate, formyl/formaldehyde, glyoxal, methylglyoxal or furan derivatives, and 1) affect the binding orientation of the intermediate, and/or 2) activate the intermediate for subsequent use with a hydride or other CO on the binding surface ₂ Reaction of the CO reaction intermediate, and/or 3) influence the binding strength of the intermediate to become stronger or weaker, and/or 4) promote the formation of new reaction intermediates on the surface. Through this effect, the promoter increases the selectivity of the carbon product towards a particular hydrocarbon or oxygenated hydrocarbon product.

The cathode may be contacted with an electrolyte solution comprising a promoter, wherein the electrically conductive support further comprises the same promoter. The electrically conductive support substrate may further incorporate a material to be reduced, whereby the electrocatalyst coating catalytically interacts with the material to be reduced incorporated into the electrically conductive support substrate. Preferably, the material to be reduced comprises carbon dioxide, carbon monoxide, mixtures thereof, or any other oxygenated hydrocarbon molecule containing aldehyde or ketone functionality and reactive alpha-hydrogen. Alternatively, the conductive carrier substrate may be an ionomer or a conductive polymer.

Another aspect of the invention relates to a method of producing an oxygenated hydrocarbon product from water, carbon dioxide, and/or carbon monoxide via an electrolysis reaction, the method comprising: (a) Placing the above-described combined cathode together with an anode in an electrolyte; (b) Bringing the anode and the cathode into conductive contact with an external current source; (c) Providing a carbon source of carbon dioxide and/or carbon monoxide to the cathode; and (d) applying an electrical current to drive an electrolytic reaction at the cathode to selectively produce oxygenated hydrocarbon products from carbon dioxide and/or carbon monoxide. In the process, the electrocatalyst and the cocatalyst are selected to produce a product selected from the group consisting of 2, 3-furandiol, 2-formylfuran-3-ol, ethylene glycol, 1, 3-propanediol, 1, 2-propanediol, stereoisomers thereof, and combinations thereof.

Preferably, the carbon dioxide source, carbon monoxide source, or any other oxygenated hydrocarbon molecule containing aldehyde or ketone functionality and reactive alpha-hydrogen is a mobile source. The flow source may be a flow reactor.

Another aspect of the invention relates to a process for reducing carbon dioxide to an oxygenated hydrocarbon product, the process comprising: (a) Placing a cathode in an aqueous electrolyte together with an anode and a promoter (as described above), wherein the cathode comprises a conductive support substrate, a promoter (as described above), and a catalyst comprising Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ Wherein the promoter may be on the conductive support, in the electrolyte, or both; (b) Bringing the anode and the cathode into conductive contact with an external current source; (c) providing a flowing source of carbon dioxide to the cathode; and (d) applying an electrical current to drive an electrolytic reaction at the anode that produces electrons that are delivered to a cathode, thereby producing oxygenated hydrocarbon products from carbon dioxide, electrons, and water, and selecting the electrocatalyst and the promoter,such that the oxygenated hydrocarbon product produced is selected from the group consisting of carbohydrates, carboxylic acids, aldehydes, ketones, and mixtures of two or more thereof.

Another aspect of the invention relates to a process for reducing carbon dioxide to an oxygenated hydrocarbon product, the process comprising: (a) Placing a cathode in an electrolyte together with an anode and a promoter, wherein the cathode comprises a conductive support substrate and an electrocatalyst coating comprising Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ ，NiP ₂ And NiP ₃ Wherein the promoter may be on the electrically conductive support, in the electrolyte, or both; wherein the cocatalyst is combined with an aldehyde, ketone, carboxylic acid, diol, or alcohol functionality of a reaction intermediate, thereby activating it for further reaction with the electrocatalyst; (b) Bringing the anode and the cathode into conductive contact with an external current source; (c) providing a flowing source of carbon dioxide to the cathode; and (d) applying an electrical current to drive an electrolytic reaction that produces electrons at the anode that are delivered to the cathode, wherein an oxygenated hydrocarbon product is produced from carbon dioxide, and the electrocatalyst and the cocatalyst are selected such that the oxygenated hydrocarbon product produced is selected from the group consisting of carbohydrates, carboxylic acids, aldehydes, ketones, and mixtures of two or more thereof. The promoter may include a metal selected from Cu, ag, au, zn and intermetallic compounds thereof. The co-catalytic metal or intermetallic compound may be a nanoparticle.

Brief Description of Drawings

FIG. 1 shows the CO ₂ Ni in the absence of promoter in purged potassium bicarbonate (electrolyte) ₃ P、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ Faradaic efficiency (electronic efficiency) of electrocatalyst. For standard H ₂ Electrode (i.e. H) ₂ Electrode, RHE).

FIG. 2 shows the CO ₂ In purged potassium bicarbonate (electrolyte)Ni in the case of two different cocatalysts ₂ Faradaic efficiency (electron efficiency) of the P electrocatalyst. The current difference between the two catalyst systems and the electrocatalyst without promoter shows the effect of the combined catalyst system. For standard H ₂ Electrode (i.e. H) ₂ Electrode, RHE).

Fig. 3A, 3B, 3C and 3D show suggested changes in the mechanism resulting from the addition of the various cocatalysts described above.

FIG. 4A shows the product ¹ H NMR demonstrated a change in selectivity upon addition of 25mM boric acid. The electrocatalyst is Ni at 0V relative to RHE at pH7.5 ₂ Solid particles of P. FIG. 4B shows the corresponding HPLC (refractive index detector trace) demonstrating the change in selectivity upon addition of 25mM boric acid. The electrocatalyst is Ni at 0V relative to RHE at pH7.5 ₂ Solid particles of P. A comparison is shown with electrolyte blank and pure ethylene glycol standards.

FIG. 5 shows ¹ H NMR spectra, which show that when copper metal is deposited onto the electrocatalyst (Ni at 0V relative to RHE at pH1 ₂ P solid particles) on the catalyst.

Detailed Description

The technology of the present disclosure relates to the preparation of oxygenated hydrocarbons, which are common chemical feedstocks that can be readily handled by existing transportation and export equipment.

CO ₂ The reduction can be carried out at room temperature by direct electrolysis, but requires at least 4 electrons (e ^- ) To form a valuable fuel (equivalent 3-7). As is evident from the potentials listed, CO ₂ The reduction takes place in the presence of the simpler 2e ^- Hydrogen release reaction (HER) (u=0v, relative to 1atm H ₂ RHE below) and most of the oxygenated hydrocarbon product (all formed at nearly the same potential).

Thus, the challenge is to produce a hydrogen equivalent (H or hydride) that preferentially provides CO ₂ Reduction to specific carbon products other than formation of products or H ₂ An electrocatalyst of a mixture of (a) and (b). Common Cu electrode-based CO ₂ The electrocatalyst was reduced to form a mixture of products, wherein the optimization result showed a selectivity to hydrocarbons of 72.3% (CH) achieved at-1.04V versus reversible hydrogen electrode ("RHE") ₄ Is the major product) that is about 1.2V more negative than the thermodynamic limit of +0.16v relative to RHE. However, this large overpotential greatly reduces energy efficiency and precludes the applicability of this approach in synthetic fuel production. Nevertheless, copper is by far the best performing single component transition metal DCRR electrocatalyst.

From CO ₂ The viable technology for producing fuels must be quantitatively compared to industrial procedures. Currently, industrial methanol production from CO is estimated to be 51% energy efficient. Theoretical maximum energy efficiency of dcrr—assuming 0V overpotential and complete productionRecovery-73%, indicating that DCRR is a technology that can theoretically significantly exceed current industry standards. Assuming oxygen evolution is an anodic reaction, then CO ₂ Electrochemical reduction (also referred to herein as "electroreduction") of CH ₄ The efficiency of (c) is currently 13% on Cu surfaces.

Replacement of the electrocatalyst (electrode) is an expensive downtime investment for any commercial process, and therefore, an extended lifetime that maintains excellent electrocatalyst performance is critical. There are very few examples of tests currently on transition metal electrodes with DCRR exceeding even 2 hours. The electrocatalyst of the invention targets continuous activity for at least 16 hours. Industrial applications require significantly longer stability than a few hours. For example, for chlor-alkali processes (based on RuO _x And IrO _x ) Has a lifetime of about 7 years.

Ni has now been described ₃ P、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ And NiP ₂ Synthesis to form direct CO for use in the present invention ₂ The approximately flat surface of the reduced electrocatalyst family is highly compacted. This allows to observe the catalytic activity directly on the most stable crystal phase termination and is directly comparable to the optimized Cu foil of the prior art. Their activity as DCRR electrocatalysts without cocatalysts is shown in the following data (fig. 1). The selectivity of these electrocatalysts to DCRR was found to be tunable based on composition and structure. The high natural abundance of Ni and P elements ensures the mass production of these electrocatalysts for industrial applications.

In addition, it has been found that the nickel phosphide electrocatalyst described above, together with the promoter, alters the carbon product selectivity by interacting with selected reaction intermediates. These cocatalysts are selected from all Lewis acids or Bronsted-Lorinoic acid Al ⁺³ 、AlO ⁺ 、Si ⁴⁺ 、SiO ²⁺ 、H ₃ BO ₃ 、H _x BO _y R _z (wherein x, y and z are each independently 0 or an integer selected from 1 to 3, wherein- (x+ (-2 y) + (z.n)) = -5 or-1 or 0 or 1 or 2 or 3, wherein for the various substitutions on R n is-1, -2 or-3), such that the boronates includeSuch as B (OH) ₂ (OR) and B (OH) (OR) ₂ And the boric acid ester includes, for example, RB (OH) ₂ And RB (OR') ₂ Wherein R and R' =alkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, wherein the heteroatoms of heteroaryl and heteroarylalkyl are selected from nitrogen, oxygen and sulfur), and mixtures of two or more thereof, or oligomer/polymer chains.

Furthermore, the anion exchange membrane allows CO ₃ ^2- And neutral CO ₂ (aqueous solution) and H ₂ O is transported to the electrocatalyst surface while limiting H due to charge repulsion ⁺ Accessibility. DCRR activity is known to be pH sensitive because higher pH increases selectivity but limits CO ₂ Availability of (3). Thus, DCRR is strongly favored over HER by locally controlling proton availability using an anion exchange membrane, rather than increasing the pH of the bulk solution. Accordingly, one aspect of the present invention relates to the binary electrocatalyst and cocatalyst of the present invention and the composite electrode of various polymers having anion conducting properties near the surface of the electrocatalyst.

Furthermore, hydrophobic polymeric materials incorporated into the electrode substrate allow neutral CO ₂ (g) To the electrocatalyst and the cocatalyst. DCRR is critically dependent on mass transport when producing liquid products or operating in liquid electrolytes. Thus, a local reduction of the transport resistance to gas molecules by excluding water caused by the hydrophobic domains is strongly advantageous for high DCRR reaction rates. Accordingly, one aspect of the present invention relates to composite electrodes of the above electrocatalyst and cocatalyst described above in various polymers having different hydrophobicity or different compositions to adjust the overall hydrophobicity of the electrode.

In another aspect, the use of anionic ionomers can be described as having HCO ₃ ^- Or CO ₃ ^2- Or H ⁺ The ionic liquid with the transmission function is replaced. In other aspects of the invention, bicarbonate, carbonate or H ⁺ The functional group is bound to a polymer or soluble molecule, wherein the soluble molecule may have variable dimensions: small, medium or large.

Results with electrocatalyst alone

Nickel phosphide (Ni ₃ P，Ni ₁₂ P ₅ ，Ni ₂ P，Ni ₅ P ₄ And NiP ₂ ) Is a piece of data of the data set. FIG. 1 also shows how Ni is used as a catalyst ₃ P (high Nickel content) to NiP ₂ (high phosphorus content) an increased DCRR selectivity at low applied voltages can be observed. At a higher applied voltage, H ₂ Is better than DCRR. Ni (Ni) ₂ P and NiP ₂ Shows the highest selectivity to DCRR, but the former favors C ₄ The latter favors C ₃ The product is obtained. This shows how, for such binary compounds, only the crystalline phase changes (same binary element), CO is bound at the surface ₂ And thus there is a significant difference in the carbon products.

Electrocatalyst Ni ₃ P、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ Or NiP ₂ None show CO production or release as a gaseous product, probably due to its lack of formation or irreversible binding on these surfaces.

CO is achieved by using a CO-catalyst ₂ High selectivity control of electroreduction

As defined herein, the promoter includes all possible additives of binary compounds of nickel and phosphorus, which modify the performance of the catalytic process without consuming itself. The additive includes any element or compound that is not a binary compound of nickel and phosphorus, less than 50% by weight of the composition.

This promoter binds to the reaction intermediate on the surface or in solution: 1) Influencing the binding orientation of the intermediate, and/or 2) activating the intermediate for subsequent use with hydrides or other CO's at the binding surface ₂ Reaction of the CO reaction intermediate, and/or 3) influence the binding strength of the intermediate to become stronger or weaker, and/or 4) promote the formation of new reaction intermediates on the surface.

The ionic promoters of the present invention are therefore conjugated acid/base pairs and charged ions, which are used with transition metal phosphide electrocatalysts as dopants incorporated during the electrocatalytic synthesis, co-deposited on the transition metal phosphide electrocatalyst, or added to the electrolyte of the immersed electrode. Other chemical terms used to refer to these cocatalysts are Lewis acid/base pairs, bronsted-Lorinic acid/base pairs (also known as Bronsted acid/base) and cations/anions, respectively. Especially for those cocatalysts in electrolyte solutions, adjusting the pH can provide a mixture of acidic and conjugate basic species. Thus, boric acid may be added to the electrolyte solution and the pH adjusted to provide a mixture of boric acid and borate species. Similarly, sodium borate may be added to the electrolyte solution and the pH adjusted to provide a mixture of boric acid and borate. In another aspect, the cocatalysts are nonionic and act as a deposit on the surface (or as a dopant in the catalyst surface) in combination with the reaction intermediate to affect the reaction on the transition metal phosphide electrocatalyst so that they can react with the transition metal phosphide surface or with the DCRR intermediate bound to the transition metal phosphide electrocatalyst surface.

It has now been shown that CO on nickel phosphide can be greatly altered by the addition of cocatalysts (i.e., unconsumed substances or materials, and which can act as soluble molecules in the electrolyte, adsorbed molecules on the electrocatalyst surface, incorporated into the electrocatalyst support or ionomer or conductive polymer, or present as dopant ions throughout the electrocatalyst bulk) ₂ The reduced product is selective. These two classes of cocatalysts are shown in FIG. 2 and Table 1 associated therewith, which shows the use of three different soluble cocatalysts in Ni at a fixed pH (7.5) in an electrolyte solution ₂ The range of products formed independently on P and their yields. Upon addition of Lewis acid-base to boric acid/borate (H ₃ BO ₃ /B(OH) ^4- ) Or cationic bronsted acid/base para-hexamethylenetetramine (C) ₆ H ₁₂ N ₄ H ⁺ /C ₆ H ₁₂ N ₄ ) When relative to the baseline product (mainly C ₃ +C ₄ ) Is directed mainly to C ₂ Major changes in product selectivity to product ethylene glycol (93% and 72%, respectively). Maintain relative to the reference Ni within the applied potential range ₂ The carbon selectivity of the P electrocatalyst was varied as shown in figure 2. In contrast, mg ²⁺ (classified as cationic or Lewis acid) forms the least C than the electrocatalyst alone ₂ Product and increased formic acid levels; however, due to MgCO ₃ The solubility limit of the cocatalyst, which may still be below a maximum of 15%. The improved process may be the use of other promoters with higher solubility or the incorporation of promoters in a conductive catalyst support located primarily in the hydrophilic region. With increasing applied negative bias, the yield of oxygenated hydrocarbon product with H over all electrocatalysts with or without promoter ₂ The yield increases and competitively decreases. This provides a direct understanding of the mechanism (see fig. 3A-3D).

TABLE 1 products and yields with or without soluble cocatalysts of the present invention

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Reaction mechanism (FIGS. 3A to 3D)

Without wishing to be bound by any particular theory, we believe that C, which binds to the surface ₂ Competition between the intermediate and regeneration of the original H-covered surface indicates the formation of C ₂ The reaction of the precursor to the final MEG product may be separated from the electrocatalyst. This information directs what type of cocatalyst is needed to enhance a particular oxygenated hydrocarbon relative to other DCRR products.

Fig. 3A and 3B. Glycolaldehyde (Glycoaldehyde) reduction: lewis (or bronsted) acid activation of the aldehyde groups of the surface-bound hydroxyaldehyde. This activates the aldehyde for reduction to the corresponding alcohol. This mechanism is supported by activation at low pH.

Fig. 3C. Glycolaldehyde-formaldehyde disproportionation reaction: lewis or bronsted base catalyzed hydrolysis of surface bound formaldehyde establishes its binding to the surfaceDisproportionation of the resultant glycolaldehyde (via intermolecular hydride transfer) forms formic acid and ethylene glycol, respectively. Base-catalyzed disproportionation of two carbonyl compounds to produce a carboxylic acid and an alcohol is an example of a type of reaction known as the Cannizzarro reaction. Further electroreduction of the formate product to form aldehydes at the electrode surface and eventually consumption of all CO ₂ To prepare ethylene glycol.

Fig. 3D. Oxalic acid route: a third possible way to fit the available data is to put the CO ₂ Inserted into the carboxylic acid C-H bond of the binding surface. This step forms oxalate, which can further react with surface hydrides to produce ethylene glycol and water.

Boric acid (Boric acid) or the corresponding esters are known to bind reversibly to glycols, such as ethylene glycol. However, the present invention incorporates the following findings: by combining the intermediate, the cocatalyst acts to reduce the energy of desorption of the intermediate from the surface, thereby making it the primary product.

Preparation of Ni by solid state synthesis ₂ P and pressed into granules. In CO ₂ Saturated electrolyte (containing 0.5M KHCO) ₃ And is selected from 25mM hexamethylenetetramine, 25mM boric acid or 1.5mM Mg ²⁺ One of the three cocatalysts) is tested at the indicated applied potential. The test was run at ambient pressure and temperature at pH 7.5 for 16 hours per experiment. The ambient temperature is typically between 70°f and 80°f. The composition of the headspace was monitored by gas chromatography and the liquid product was analyzed by HPLC and NMR.

FIG. 4A shows an electrolyte ¹ H NMR, where the main peak was ethylene glycol (confirmed by the HPLC trace of fig. 4B), confirmed the change in selectivity caused by the addition of the cocatalyst.

The promoters are effective when applied to all members of the nickel phosphide family of electrocatalysts disclosed above, including Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ And one or more of the above Ni _x P _y Compounds and Fe ₂ Electrocatalyst nanoparticles of an alloy of P, wherein the alloy has from 100:0 to 0:100wt%, preferably about 99:1-1:99wt% Ni-P: fe ₂ P ratio. Particularly preferred nickel phosphides for promoters include Ni ₃ P、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ And NiP ₂ 。

The concentration of the promoter in the electrolyte may be from very low to its solubility limit and is typically from about 0.1mM to about 10mM. Preferably, the concentration of the promoter ranges from about 0.5mM to about 5mM. Alternatively, the concentration of the promoter may range from about 1mM to about 1M, or from about 1mM to about 100mM, or from about 1.5mM to about 50mM, or from about 1.5mM to about 25mM. The concentration of the soluble promoter may be from about 0.1mM to about 100mM. The promoter may be present in the electrolyte at about 1.5mM or about 25mM.

As disclosed herein, a number of numerical ranges are provided. It is to be understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range is also specifically disclosed. Every smaller range between any stated value or intermediate value within the range and any other stated value or intermediate value within the range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where any, none, or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. The term "about" generally includes up to plus or minus 10% of the indicated amount. For example, "about 10%" may represent a range of 9% to 11%, and "about 20" may represent 18 to 22. Preferably, "about" includes up to plus or minus 6% of the indicated value. Alternatively, "about" includes up to plus or minus 5% of the indicated value. Other meanings of "about" may be apparent from the context, such as rounding, so that, for example, "about 1" may also mean 0.5 to 1.4.

Alternatively, a promoter in the form of a second catalytic metal may be added to the surface, or another metal (or metal ion) may be doped into/onto the surface, or within the bulk of the electrocatalyst. The promoters of the present invention include all possible additives to the binary compounds of nickel and phosphorus, which modify the performance of the catalytic process without consuming itself.

The second promoting metal or metal ion must be selected from CO known to promote DCRR ₂ Or reduced groups of CO or other reaction intermediates. This includes, but is not limited to, metals such as Cu, ag, au, zn, and intermetallic or oxide compounds thereof. The promoter metal, intermetallic compound or oxide is preferably a nanoparticle having a size in the range of about 0.1 to about 1000 nm. The promoter particle size may be from about 0.5nm to about 1000nm, or from about 0.5nm to about 500nm, or from about 0.5nm to about 50nm, or from about 0.5nm to about 20nm. The particle size of the cocatalyst can be from about 0.1nm to about 500nm, or from about 0.1nm to about 50nm, or from about 0.1nm to about 5nm, or from about 0.1nm to about 2nm.

Depositing such promoters on nickel phosphide alters the selectivity of the reaction by altering the population and binding affinity of the reaction intermediates on the surface. In FIG. 5 ¹ H NMR spectrum shows that in Ni ₂ Electrodepositing copper metal on P nano particles or Ni ₂ CO formed on P nanoparticles upon electrodeposition at 0V and acidic pH relative to RHE ₂ And (5) reducing the product. The data indicate the formation of two C' s ₅ The compounds (3-hydroxy-2-furfural and 2-hydroxy-3-furfural).

Flow system

In this context, it has been demonstrated that binary transition metal phosphide electrocatalyst compounds in combination with cocatalysts have a surprising DCRR carbon product selectivity to hydrocarbons or oxygenated hydrocarbons. In switching to wherein CO ₂ The carbonaceous product is formed at a higher rate and higher concentration as it passes continuously through the flow reactor of the working electrode. This forms a further aspect of the invention.

One aspect of the invention relates to a combination of: 1) For straightening carbon dioxide and/or carbon monoxide with any other added hydrocarbon molecules containing aldehyde or ketone functionalities and reactive alpha-hydrogenA cathode for electrochemical reduction to an oxygenated hydrocarbon product, the cathode comprising a conductive carrier substrate and an electrocatalyst coating comprising Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ The method comprises the steps of carrying out a first treatment on the surface of the Or comprises Ni _x P _y The electrocatalyst coating of the nanoparticles of (2) is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ And further with Fe ₂ P alloying, wherein the alloy has about 99:1 to 1:99wt% Ni-P: fe ₂ P ratio; wherein the electrically conductive carrier substrate comprises hydrophobic and hydrophilic regions to facilitate adsorption of carbon dioxide and/or carbon monoxide from a gas or aqueous phase to effect separation from water molecules, wherein at least some of the electrocatalyst nanoparticles are located in the hydrophobic regions of the electrically conductive carrier substrate and catalytically interact with carbon dioxide and/or carbon monoxide by electroreduction to produce oxygenated hydrocarbon products; and 2) a promoter other than nickel phosphide for reducing carbon dioxide and/or carbon monoxide positioned to act with the electrocatalyst. Ni-P Fe ₂ The P ratio may be about 99:1 to about 1:99wt%. NiP: fe ₂ The P ratio may be about 95:5 to about 5:95wt%. Ni-P Fe ₂ The P ratio may be about 90:10 to about 10:90wt%. Ni-P Fe ₂ The P ratio may be about 25:75 to about 75:25wt%.

The cocatalyst may comprise an acid; the acid may be selected from Lewis acids or Bronsted-Loli acids. The acid is selected from Zn ⁺² 、Fe ⁺² 、Fe ³⁺ 、Ca ²⁺ 、Mg ²⁺ 、Al ⁺³ 、AlO ⁺ 、Si ⁴⁺ 、SiO ²⁺ 、H ₃ BO ₃ 、H _x BO _y R _z (wherein x, y and z are each independently 0 or an integer selected from 1 to 3, wherein- (x+ (-2 y) + (z·n)) = -5 or-1 or 0 or 1 or 2 or 3, wherein for the various substitutions on R n is-1, -2 or-3), such that boron Acid esters include, for example, B (OH) ₂ (OR) and B (OH) (OR) ₂ Wherein r=alkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, wherein the heteroatoms of heteroaryl and heteroarylalkyl are selected from nitrogen, oxygen and sulfur), and mixtures of two or more thereof. Suitable r=alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl. Suitable r=aryl groups include, but are not limited to, phenyl, biphenyl, and naphthyl, optionally substituted with one or more of halogen, alkoxy, alkylthio, alkyl, cyano, nitro, alkyl sulfoxide, alkyl sulfone, aryl sulfone.

The cocatalyst may comprise a catalyst of formula H having an oxidation state of-5, -1, 0, +1, +2 or +3 _x BO _y R _z Such that the integers x, y and z are defined by the equation- (x+ (-2 y) + (z·n)) = -5 or-1 or 0 or 1 or 2 or 3; wherein for each substitution on R, n is-1, -2 or-3, wherein R is as defined above. Except for boric acid esters B (OH) ₂ (OR) and B (OH) (OR) ₂ (wherein r=ch ₃ Alkyl, C ₆ H ₅ Aryl, etc.), when x or y is 0, this also includes (C) ₆ H ₅ ) ₃ B (triphenylborane) and H ₃ NBH ₃ When z is 0, H is also included ₃ BO ₃ (boric acid) and BH ₃ 。

The cocatalyst may comprise a base; the base may be selected from lewis bases or langnsted-loli bases. The base may be selected from NH ₃ A carboxamide, urea, hydrazine, primary amine, secondary amine, tertiary amine, pyridine, and mixtures of two or more thereof.

The cathode may be contacted with an electrolyte solution containing a promoter, or the promoter may be a promoter having HCO ₃ ^- Or CO ₃ ^2- Or H ⁺ An ionic liquid electrolyte that transports the function and is in contact with the cathode. Alternatively, the cocatalyst may be an ionomer or a conductive polymer.

Further, the cocatalyst may include a soluble salt of Cu, ag, au, zn, a mixture of two or more thereof, or a salt or oxide thereof. The salt or oxide becomes soluble at the appropriate pH. Alternatively, the promoter may comprise a simple metal or alloy selected from Cu, ag, au, zn and intermetallic compounds thereof. The co-catalytic metal or intermetallic compound may be in the form of nanoparticles. The promoter metal, intermetallic or oxide nanoparticle is about 0.1 to about 1000nm in size. The promoter particle size may be from about 0.5nm to about 1000nm, or from about 0.5nm to about 500nm, or from about 0.5nm to about 50nm, or from about 0.5nm to about 20nm. The promoter particle size may be from about 0.1nm to about 500nm, or from about 0.1nm to about 50nm, or from about 0.1nm to about 5nm, or from about 0.1nm to about 2nm.

Without wishing to be bound by any particular theory, it is believed that the combined cocatalysts described above bind to the reaction intermediate on the electrocatalyst surface or in solution and 1) affect the binding orientation of the intermediate, and/or 2) activate the intermediate for subsequent use with the hydride or other CO at the binding surface ₂ Reaction of the CO reaction intermediate, and/or 3) influence the binding strength of the intermediate to become stronger or weaker, and/or 4) promote the formation of new reaction intermediates on the surface.

The cathode may be contacted with an electrolyte solution comprising a promoter, wherein the electrically conductive support further comprises the same promoter. The electrically conductive support substrate may further incorporate a material to be reduced whereby the electrocatalyst coating catalytically interacts with the material to be reduced incorporated into the electrically conductive support substrate. Preferably, the material to be reduced comprises carbon dioxide, carbon monoxide or a mixture thereof. Alternatively, the conductive carrier substrate may be an ionomer or a conductive polymer.

Another aspect of the invention relates to a process for producing oxygenated hydrocarbon products from water, carbon dioxide and/or carbon monoxide via an electrolysis reaction by: (a) Placing a combination of an electrocatalyst-coated cathode and a promoter in an electrolyte together with an anode; (b) placing the anode and cathode in conductive contact with an external current source; (c) Providing a carbon source of carbon dioxide and/or carbon monoxide to the cathode; and (d) applying an electrical current to drive an electrolytic reaction at the cathode, thereby selectively producing oxygenated hydrocarbon products from carbon dioxide and/or carbon monoxide. In the process, the electrocatalyst and the cocatalyst are selected to produce a product selected from the group consisting of 2, 3-furandiol, 2-formylfuran-3-ol, ethylene glycol, 1, 3-propanediol, 1, 2-propanediol, stereoisomers thereof, and combinations thereof.

Preferably, the carbon dioxide and/or carbon monoxide source is a mobile source. The flow source may be a flow reactor.

Another aspect of the invention relates to a process for reducing carbon dioxide to an oxygenated hydrocarbon product by: (a) Placing a cathode in an aqueous electrolyte together with an anode and a promoter of an acid or base or a charged ionic species, wherein the cathode comprises a conductive carrier substrate, a promoter comprising an acid or base or a charged ionic species, and Ni _x P _y Electrocatalyst coating of nanoparticles, wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ Wherein the promoter may be on the electrically conductive support, in the electrolyte, or both; (b) placing the anode and cathode in conductive contact with an external current source; (c) providing a flowing source of carbon dioxide to the cathode; and (d) applying an electrical current to drive an electrolytic reaction that produces electrons at the anode that are delivered to the cathode, thereby producing an oxygenated hydrocarbon product from carbon dioxide, electrons, and water, and selecting the electrocatalyst and the cocatalyst such that the oxygenated hydrocarbon product produced is selected from the group consisting of carbohydrates, carboxylic acids, aldehydes, ketones, and mixtures of two or more thereof.

Yet another aspect of the invention relates to a process for reducing carbon dioxide to an oxygenated hydrocarbon product by: (a) Placing a cathode in an electrolyte together with an anode and a promoter, wherein the cathode comprises a conductive support substrate and an electrocatalyst coating comprising Ni _x P _y Wherein x and y are integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ Wherein the promoter may be on the electrically conductive support, in the electrolyte, or both; wherein the cocatalyst isTo the aldehyde, ketone or alcohol functions of the reaction intermediates, thereby activating them for further reaction with the electrocatalyst; (b) placing the anode and cathode in conductive contact with an external current source; (c) providing a flowing source of carbon dioxide to the cathode; and (d) applying an electrical current to drive the electrolytic reaction to produce electrons at the anode that are delivered to the cathode, wherein an oxygenated hydrocarbon product is produced from carbon dioxide, and the electrocatalyst and the cocatalyst are selected such that the oxygenated hydrocarbon product produced is selected from the group consisting of carbohydrates, carboxylic acids, aldehydes, ketones, and mixtures of two or more thereof. The promoter may be a metal selected from Cu, ag, au, zn and intermetallic compounds thereof. The co-catalytic metal or intermetallic compound may be a nanoparticle.

The electrocatalysts in the following examples were synthesized and characterized by physical characterization methods to determine their atomic structure and their HER activity was tested by electrochemical and gas chromatography. The electrocatalyst of the invention may be supported on the titanium membrane electrode, for example, by being pressed into particles and bonded to the titanium membrane electrode by silver paint and encapsulated in a non-conductive epoxy. Alternatively, the electrocatalyst may be supported on carbon or ceramic powders.

The particle size of the as-synthesized electrocatalyst of the present disclosure is from about 5nm to about 5000nm, preferably from about 5nm to about 1000nm, more preferably from about 5nm to about 500nm, even more preferably from about 5nm to about 20nm. The particle size may be from about 10 to about 4000nm, or from about 25nm to about 3000nm, or from about 50nm to about 2500nm. The particle size may be at least 100nm. These particles are part of larger 0.3 μm-1.8 μm spherical particle agglomerates. Found in 1M H ₂ SO ₄ The durability of the electrocatalyst under the electrolysis conditions in acid and 1M NaOH is very good. Evidence comes from demonstration of electrochemical stability and X-ray fluorescence of the atomic composition of the surface, as well as macroscopic physical appearance.

Carrier substrate

According to another aspect of the invention, an electrocatalyst includes a catalytic group and an electrically conductive carrier substrate supporting a plurality of catalytic groups. The carrier substrate is capable of binding hydrogen cations and at least some of the catalytic groups supported by the carrier substrate are capable of catalytically interacting with the hydrogen cations bound to the carrier substrate. The carrier substrate is capable of binding water molecules, and at least some of the catalytic groups supported by the carrier substrate are capable of catalytically interacting with water molecules bound into the carrier substrate. The support substrate is capable of binding carbon dioxide, and at least some of the catalytic groups supported by the support substrate are capable of binding CO incorporated into the support substrate ₂ The molecules interact catalytically. The support substrate is capable of incorporating a promoter, and at least some catalytic groups comprising the support substrate are capable of catalytically interacting with the promoter incorporated into the support substrate.

The carrier substrate has a plurality of porous regions that are microporous, mesoporous, and/or macroporous. The support substrate may be a microporous substrate having an average pore size of less than about 2 nm. The support substrate may be a mesoporous substrate having an average pore size of from about 2 to about 50 nm. The support substrate may be a macroporous substrate having an average particle size greater than about 50 nm.

The carrier substrate is electrically conductive to electrons such that when there is a potential difference across the separation points on the carrier substrate, mobile charges within the carrier substrate are forced to move and a current is generated between these points. The carrier substrate may be made conductive by applying a thin layer of the carrier substrate over the conductive material. Suitable conductive materials include glassy carbon, carbon nanotubes and nanospheres, titanium foil/wire/mesh/foam/braid mesh, aluminum foil/wire/mesh/foam/braid mesh, fluoride doped tin oxide (FTO or ((F) SnO) ₂ ) Glass coated with Indium Tin Oxide (ITO) (or any transparent conductive oxide), and multilayer structures having nanostructured semiconductor films coated on conductive substrates. Other ways of making the carrier substrate conductive are within the scope of the invention. For example, the carrier substrate may contact the sensitized semiconductor.

Preferably, the support substrate has hydrophobic and hydrophilic regions and aids in the functioning of the promoter. Concerning water or CO ₂ While not wishing to be bound by theory, it is believed that at least some of the catalytic groups may be supported in the hydrophobic regions of the support substrate and, once supported, be able to interact with water or CO in the hydrophilic regions ₂ The molecules interact catalytically. Effectively, the carrier substrate is consideredAs hydrogen cations, water molecules or CO ₂ An interface between the molecule and a catalytic group that is insoluble in aqueous solutions.

The hydrophobic region may be formed from a hydrophobic polymer backbone and the hydrophilic region is a region of ionizable functional groups, preferably on the polymer backbone, which may serve as sites for proton conduction. Preferably, the ionizable functional group is a sulfonate group (-SO) ₃ H) It loses protons to form negatively charged sulfonate groups. Alternatively, if preferred, the ionizable functional groups may form positively charged functional groups that can serve as sites for hydroxyl or carbonate ion conductance.

The carrier substrate may be, for example, polysulfone, polysulfonate, and polyphosphonate. The carrier substrate may comprise a sulfonated fluoropolymer (under the trademark

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Is (F) hydrophobic CF ₂ CF(CF ₃ ) The O-polymer backbone forms a hydrophobic solid that is penetrated by aqueous channels lined with hydrophilic ionizable sulfonic acid groups. For>

Studies of the substructure of the coating have revealed that the polymer layer contains these hydrophilic channels in other hydrophobic regions of the membrane. These channels allow diffusion of small molecules such as water.

Other carrier substrates that may be used include, for example, perfluorinated sulfonic acid polymer cation exchange membranes such as F-14100, F-930, and F-950, GEFC perfluorinated proton exchange membranes, polysulfone ionomers, nanostructured membranes formed by metal oxide nanoparticles suitably modified with organic acids (including perfluorinated sulfonic acids), nanostructured membranes formed by hydrolysis of alkoxysilanes suitably modified with organic acids (including perfluorinated sulfonic acids).

Other carrier substrates may be, for example, polyfluorinated Alkaline Exchange Membranes (AEMs), which rely on polymersTo prevent conduction of protons and to allow conduction of mobile anions for conductivity. Examples of commercial AEMs include

AEM. Also within the scope are heterogeneous colloidal systems, two-phase (biphasic) mixtures (stable and unstable with surfactants), conductive polymers (e.g., poly (3, 4-ethylenedioxythiophene) (PEDOT)), surface-modified silica and titania.

Other carrier substrates that may be used to aid in the promoter function include borate/boric acid or amine/ammonium functionalized polymers having alkyl or aryl or polyfluorinated polymer backbones.

Other carrier substrates that may be used to facilitate the hydrophobic functional domains include alkyl or aryl or polyfluorinated polymer backbone polymers.

By mixing electrocatalyst with water and CO ₂ Or any manner of contacting carbonate minerals is within the scope of the present invention. The electrocatalyst may be immersed in the solution containing water molecules. The solution may be an aqueous solution containing an electrolyte. The aqueous solution may be a solution that preferentially removes water (i.e., solid-liquid separation). For example, when the aqueous solution is brine or seawater, the water can be removed, leaving behind salts (i.e., desalinated). In one example, about 0.5M electrolyte is sufficient.

The following examples are provided to further illustrate the methods and compositions of the present invention. These examples are illustrative only and are not intended to limit the scope of the invention in any way.

Examples

Example 1 electrode fabrication

1g of the electrocatalyst powder was neutralized with 250. Mu.L of 5% pre-neutralized with NaOH

The suspensions are mixed. The electrocatalyst powder was mixed with +.>

The suspension was continuously mixed until dry. In order to allow them to dry completely, they are dried further under vacuum for several hours.

The resulting electrocatalyst/polymer composite was pressed in a 30mm diameter die at a pressure of 5 to 29 tons. The resulting pellets were mounted on a conductive aluminum support using Kapton tape. The geometric surface area is determined using a silicone polymer gasket having a predetermined opening on the exposed surface.

Example 2 electrochemical measurement

Using

All solutions were prepared with water. Will have a working compartment (working compartment) and a counter compartment (counter compartment)>

Three-electrode devices of membrane or anion exchange membrane separators are used for all electrochemical measurements. A Pt or Ir/C electrode was used as counter electrode during the measurement. Using Hg/HgSO ₄ (saturated KCl) reference electrode and was calibrated against a commercially available saturated Calomel electrode (Hack) at open circuit potential prior to each measurement. The timing amp meter data for the IR drop was manually compensated by measuring the IR drop before and after the experiment and manually applying the correct bias.

Using reagents of high purity grade

Water prepares the electrolyte. In addition, as a further precaution for removing potential metallic impurities, by +.>

The solution was filtered through a 100-substrate. The electrolyte was stored in Piranha clean flasks until use. Before measurement, use CO ₂ (Airgas CD 1200) saturated electrolyte, cleaned to<6ppm CH ₄ (major hydrocarbon impurities).

Ar Carrier gas was used on HP5890 series II GC with 5A MSieve (Restek) 0.53mm capillary column (in Supelco hydrocarbon, moisture trapUpper clean hydrocarbon and moisture) for product analysis. Using a mixture of gases identified, i.e. 1.04% CH from Airgas ₄ Ar, 1.02% H likewise from Airgas ₂ Ar and pure C ₂ H ₄ Calibration is performed.

And (3) preparing a catalyst: solid state synthesis

1.5mol% of a stoichiometric excess of red phosphorus (Alfa-Aesar 99%) and a stoichiometric amount of nickel (Sigma-Aldrich <150 μm) were thoroughly mixed in a mortar. Transferred into a quartz tube, evacuated and sealed by backfilling 2 to 3 times after cleaning with Ar. The evacuated tube was placed in a furnace and warmed to 700 ℃ and held in the furnace for 24 hours. The rate of temperature rise is moderate to avoid excessive heating during the reaction. The temperature was increased from 80 ℃ to 250 ℃ over 580min for a residence time of 360min, then 300min to 350 ℃,200min for a residence time, then 300min to 450 ℃,200min for a residence time, and finally 350min to 700 ℃,24 hours for a residence time. The sample was then cooled to room temperature under ambient conditions. The sample purity was checked by powder X-ray diffraction (PXRD) and, if necessary, additional Ni or P was added, mixed and sealed as described above, and reheated using an acceleration sequence (580 minutes, from 80 ℃ to 750 ℃,24 hours residence time).

The preparation of nanoparticulate nickel phosphide was started from 20nm Ni nanoparticles (99.9% USNano ltd.) which were gently mixed with 101.5mol% of red P in a glove box under Ar. The sample was sealed in a evacuated quartz tube and slowly heated to 450 ℃ with a residence time of 48 hours. The temperature was increased to 80 to 175 ℃ over 580min, followed by a residence time of 360min, to 250 ℃ over 580min, followed by a residence time of 360min, followed by a temperature increase of 350 ℃ over 360min, followed by a residence time of 300min, followed by a final temperature increase of 450 ℃ over 360min, followed by a residence time of 48 hours. The samples were cooled to room temperature under ambient conditions and checked for phase purity by PXRD. Additional P may then be added to the air, similar to the solid state reaction in 1). The additional P addition had a ramp rate of from 80℃to 450℃over 580min and a residence time of 48 hours. Occasionally, a small amount of Ni (PO) is formed during air exposure ₃ ) ₂ Impurities, and this phase was removed by acid washing in dilute HCl (about 1:10 by volume of concentrated HCl: water).

Irradiation with Cu K.alpha.1 on a Bruker AXS D8 advanced x-ray diffractometer

The scanning time of 1 hour or 12 hours and the 2 theta range of 15-70 degrees or 10-120 degrees are used for carrying out crystal phase characterization. Samples were analyzed by dispersing the powder between two glass microscope slides prior to electrochemical testing.

EXAMPLE 3 Synthesis of Ni ₂ P electrocatalyst

The electrocatalyst was synthesized using a hydrothermal method. In a typical experiment 3.685g NiCl ₂ .6H ₂ O (Sigma-Aldrich), 1.09g of hexamethylenetetramine (Sigma-Aldrich) was dissolved in 340ml of Millipore water. The solution was thoroughly mixed with 75g of red phosphorus (Alfa-Aesar, 98.9%,325 mesh) by stirring. The mixture was charged into a PTFE-lined autoclave and heated to 180 ℃ for 10 hours. After recovery, the samples were washed in water, 3% hydrochloric acid, water and acetone and then dried under vacuum overnight at 30-60 ℃. The final product was checked by PXRD.

EXAMPLE 4 characterization of Ni ₂ P nanoparticles

PXRD analysis in the use of Cu K alpha X-ray tube

Bruker AXS D8Advance, a scan time of 1 hour or 12 hours, and a 2 theta range of 15-70 DEG or 10-120 deg. Samples were analyzed prior to electrochemical testing by dispersing the powder on a glass microscope slide and planarizing the powder surface using another glass slide.

And (3) preparing a catalyst: hydrothermal or solvothermal processes

Nanoparticles were also successfully prepared by hydrothermal or solvothermal methods as described in the literature:

Henkes,A.E.,and Schaak,R.E.(2007).Trioctylphosphine:A general phosphorus source for the low-temperature conversion of metals into metal phosphides.Chemistry of Materials,19(17),4234–4242.doi:10.1021/cm071021w

Laursen,A.B.,Patraju,K.R.,Whitaker,M.J.,Retuerto,M.,Sarkar,T.,Yao,N.,…Dismukes,G.C.(2015).Nanocrystalline Ni5P4:a hydrogen evolution electrocatalyst of exceptional efficiency in both alkaline and acidic media.Energy Environ.Sci.,8(3),1027–1034.doi:10.1039/C4EE02940B

Muthuswamy,E.,Savithra,G.H.L.,and Brock,S.L.(2011).Synthetic Levers Enabling Independent Control of Phase,Size,and Morphology in Nickel Phosphide Nanoparticles.ACS Nano,5(3),2402–2411.doi:10.1021/nn1033357

Prins,R.,and Bussell,M.E.(2012).Metal Phosphides:Preparation,Characterization and Catalytic Reactivity.Catalysis Letters,142(12),1413–1436.doi:10.1007/s10562-012-0929-7

current efficiency measurement on grade 4.0 CO ₂ Purging the electrochemical cell and electrolyte was performed after 20-60 minutes and further purified with a hydrocarbon trap (Supelpure HC). CO in the electrolytic process ₂ Is 5sccm, as measured by a gas mass flow controller. A constant potential is applied for 16-20 hours. The GC autosampler was injected with 500 μl of sample from the effluent gas every 30 minutes. The Current Efficiency (CE) is then calculated using the following equation:

where n is the number of moles of a given product, F is the Faraday constant, e is the number of electrons needed to produce one product molecule (for H ₂ Is 2 for CH ₄ 8 for C ₂ H ₄ 12),

is the gas flow rate (mL/s) divided by the sample volume (0.50 mL) and I is the current.

EXAMPLE 8 gas chromatography

The gaseous product was quantified using an HP 5890 series II gas chromatograph equipped with TCD and FID detectors arranged in series and a 30m megabore molecular sieve 5A column (Restek). GC was calibrated with a gas standard and the moles of product in the cell headspace were determined by ideal gas law.

EXAMPLE 9 reaction in the Presence of Co-catalyst

Such as Calvinho, k.u.d., laurs, a.b., yap, k.m.k., goetjen, t.a., hwang, s, mejia-Sosa, b., lubarski, a., tee, k.m., murali, n., hall, e.s., garfunkel, e., greenblatt, m., and Dismukes, g.c., "Selective CO ₂ Reduction to C ₃ and C ₄ Oxyhydrocarbons on Nickel Phosphides at Overpotentials as Low as 10mV”Energy&Environmental Science,2018,11,2550-2559, ni is prepared by solid state synthesis ₂ P and pressed into granules.

In CO ₂ Saturated electrolyte (containing 0.5M KHCO) ₃ And a cocatalyst (25 mM hexamethylenetetramine, 25mM boric acid or 1.5mM Mg) ²⁺ ) Is a solution of (2) under a constant applied potential ₂ P particles. The test was carried out at ambient pressure and temperature at pH7.5 for 16 hours per experiment. The composition of the headspace was monitored by gas chromatography and Energy was measured according to Calvinho et al&The liquid product was analyzed by HPLC and NMR as described in Environmental Science,2018,11,2550-2559. Fig. 4A shows NMR of the electrolyte, where the main peak is ethylene glycol, confirming the change in selectivity caused by the addition of the cocatalyst. The results were confirmed by HPLC using a refractive index detector showing boric acid and ethylene glycol as main peaks (fig. 4B).

Deposition of metal or metal cation promoters on nickel phosphide also alters the selectivity of the reaction by changing the layout and binding affinity of the reaction intermediates on the surface. In FIG. 5 ¹ H NMR spectra showed Ni at 0V and acidic pH relative to RHE ₂ Electrodepositing copper metal or CO formed from soluble Cu salts on P nanoparticles ₂ And (5) reducing the product. The data indicate the formation of two C' s ₅ The compounds (3-hydroxy-2-furfural and 2-hydroxy-3-furfural).

Carbon dioxide conversion challenge for NASA

CO ₂ The transformation challenge is 1 provided by NASAMillions of dollars contests fund to convert carbon dioxide to sugars, such as glucose, which is a step in creating mission critical resources, especially for future Mars missions. This technology would allow the manufacture of products using the resources inherent locally on the Mars by using waste and atmospheric carbon dioxide as resources, and would be applicable to the earth.

On earth, plants will CO ₂ Is converted into carbohydrates and oxygen, providing food and breathable air. Mars have no plants but are rich in CO ₂ . When astronauts begin to explore mars, they will need to use local resources to release the launch cargo hold for other mission critical supplies. Thus, NASA is seeking to convert CO ₂ A new method of conversion to useful compounds such as sugars would be key to providing a supply for human seekers for long-term tasks of sparks.

CO of NASA ₂ The phase 2 challenge of the conversion has just begun with the aim of building a system that proves CO ₂ In combination with hydrogen, and without the use of plants, to produce simple sugars, such as glucose. The selective, effective CO-catalyst technology described herein provides for meeting CO ₂ One solution to the requirement of conversion challenges.

Industrial application

For CO ₂ The electrocatalyst for direct reduction to hydrocarbons may be achieved by a flow electrolyzer of a type similar to the chlor-alkali production cells currently used on an industrial scale. CO ₂ The source may be a point source, such as a power station, cement plant, or similar large CO ₂ The exhaust industry, or directly from the atmosphere. Ni (Ni) _x P _y The phase will be applied as nano-or microparticles (5-5000 nm) on the conductive substrate electrode. One or more may be used with or without proton or CO ₂ A polymer of coordinated chemical binding groups to immobilize the particles. The polymer may be of the same type as the support membrane that conducts ions from the anode to the cathode. Electrolysis can be performed at about neutral pH using carbonate, phosphate, KCl or sulfate electrolytes.

The invention is thatNi of (2) _x P _y Together with the co-catalyst system has the potential to be a direct alternative to fossil feedstocks (crude oil, coal and natural gas) as a source of chemical feedstock and energy storage. The carbon neutral synthetic fuels produced by this technology would eliminate the need for expensive and environmentally-friendly fossil fuel supply chains (mining/drilling, pipeline/tanker, refinery). The fuel may be manufactured at strategic locations near the hub (hub) as desired. The carbon chemistry feedstock may be custom made and not the result of inefficient processing of raw fossil materials.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. Furthermore, while the invention has been described with reference to the foregoing specific embodiments and examples, it should be understood that other embodiments utilizing the concepts of the invention are possible and within the skill of those in the art without departing from the scope of the invention. Accordingly, the foregoing preferred embodiments should be construed as merely illustrative, and not limitative of the disclosure in any way whatsoever.

Claims (24)

1. A combination of:

a cathode for the direct electrochemical reduction of a feedstock to an oxygenated hydrocarbon product, the feedstock comprising one or more of carbon dioxide, carbon monoxide and a carbohydrate comprising an aldehyde or ketone functional group having active alpha-hydrogen, the cathode comprising a conductive support substrate, a promoter other than nickel phosphide, and an electrocatalyst coating comprising Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ The method comprises the steps of carrying out a first treatment on the surface of the Or comprises Ni _x P _y Is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ Further and withFe ₂ P alloying, wherein the alloy has about 99:1 to 1:99wt% Ni-P: fe ₂ P ratio;

wherein the electrically conductive carrier substrate comprises hydrophobic and hydrophilic regions to facilitate adsorption of the feedstock from a gas or aqueous phase to effect separation from water molecules, wherein at least some of the electrocatalyst nanoparticles are in the hydrophobic regions of the electrically conductive carrier substrate and catalytically interact with the feedstock by electroreduction to produce oxygenated hydrocarbon products; and

wherein the promoter is positioned to act with the electrocatalyst by incorporation into the hydrophilic or hydrophobic regions, or by dissolution in the electrolyte, or by direct anchoring/incorporation into the catalyst surface.

2. The combination of claim 1 wherein the cocatalyst comprises an acid selected from the group consisting of lewis acids or bronsted-lolic acids.

3. The combination of claim 2 wherein the acid is selected from Zn ⁺² 、Fe ⁺² 、Fe ³⁺ 、Ca ²⁺ 、Mg ²⁺ 、Al ⁺³ 、AlO ⁺ 、Si ⁴⁺ 、SiO ²⁺ 、H ₃ BO ₃ 、B(OH) ₂ (OR)、B(OH)(OR) ₂ And mixtures of two or more thereof, wherein R = alkyl, aryl, arylalkyl, heteroaryl, and heteroarylalkyl, wherein the heteroatoms of the heteroalkyl and heteroarylalkyl groups are selected from nitrogen, oxygen, and sulfur.

4. The combination of claim 1 wherein the co-catalyst comprises a base selected from the group consisting of lewis bases and bronsted-lore bases.

5. The combination of claim 4 wherein the base is selected from the group consisting of NH ₃ A carboxamide, urea, hydrazine, primary amine, secondary amine, tertiary amine, pyridine, and mixtures of two or more thereof.

6. The combination of claim 1, wherein the cocatalyst comprises an ionomer or a conductive polymer.

7. The combination of claim 1 wherein the promoter comprises a soluble salt of Cu, ag, au, zn, a mixture of two or more thereof, or an oxide thereof.

8. The combination of claim 1, wherein the cathode is contacted with an electrolyte solution comprising the promoter, or the promoter is HCO-bearing ₃ ^- Or CO ₃ ^2- Or H ⁺ An ionic liquid electrolyte that transports functionality and is in contact with the cathode.

9. The combination of claim 8, wherein the cathode is in contact with the electrolyte solution comprising the promoter, and the electrically conductive support further comprises the same promoter.

10. The combination of claim 1 wherein the cocatalyst is a catalyst having HCO ₃ ^- Or CO ₃ ^2- Or H ⁺ And (3) transmitting functional ionic liquid.

11. The combination of claim 1, wherein the electrically conductive carrier substrate further incorporates a material to be reduced, whereby the electrocatalyst coating catalytically interacts with the material to be reduced incorporated into the electrically conductive carrier substrate.

12. The combination of claim 11, wherein the material to be reduced comprises carbon dioxide, carbon monoxide or a mixture thereof.

13. The combination of claim 1, wherein the conductive carrier substrate is an ionomer or a conductive polymer.

14. The combination of claim 1, wherein the feedstock comprises a plurality of hydrocarbon molecules containing aldehyde or ketone functional groups or reactive alpha-hydrogens.

15. A process for producing oxygenated hydrocarbon products from water, carbon dioxide, and/or carbon monoxide via an electrolysis reaction, the process comprising:

(a) Placing the combined cathode of claim 1 in an electrolyte with an anode;

(b) Bringing the anode and the cathode into conductive contact with an external current source;

(c) Providing a source of carbon dioxide and/or carbon monoxide to the cathode; and

(d) An electrical current is applied to drive an electrolytic reaction at the cathode to selectively produce oxygenated hydrocarbon products from carbon dioxide and/or carbon monoxide.

16. The method of claim 15, wherein the electrocatalyst and the cocatalyst are selected to produce a product selected from the group consisting of 2, 3-furandiol, 2-formylfuran-3-ol, ethylene glycol, 1, 3-propanediol, 1, 2-propanediol, stereoisomers thereof, and combinations thereof.

17. The method of claim 15, wherein the source of carbon dioxide and/or carbon monoxide is a flow source.

18. A process for reducing carbon dioxide to an oxygenated hydrocarbon product, the process comprising:

(a) Placing a cathode comprising a conductive carrier substrate and a catalyst comprising an acid or base or a charged ionic species in an aqueous electrolyte together with an anode, wherein the cathode comprises Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ 、NiP ₂ And NiP ₃ Wherein the promoter may be on the conductive support, in the electrolyte, or both;

(b) Bringing the anode and the cathode into conductive contact with an external current source;

(c) Providing a flowing source of carbon dioxide to the cathode; and

(d) Applying an electrical current to drive an electrolytic reaction that produces electrons at the anode that are delivered to the cathode, thereby producing an oxygenated hydrocarbon product from carbon dioxide, electrons, and water, and selecting the electrocatalyst and the cocatalyst such that the oxygenated hydrocarbon product produced is selected from the group consisting of carbohydrates, carboxylic acids, aldehydes, ketones, and mixtures of two or more thereof.

19. A process for reducing carbon dioxide to an oxygenated hydrocarbon product, the process comprising:

(a) Placing a cathode in an electrolyte together with an anode and a promoter, wherein the cathode comprises a conductive support substrate and an electrocatalyst coating comprising Ni _x P _y Wherein x and y represent integers such that the compound is selected from Ni ₃ P、Ni ₅ P ₂ 、Ni ₁₂ P ₅ 、Ni ₂ P、Ni ₅ P ₄ ，NiP ₂ And NiP ₃ Wherein the promoter may be on the electrically conductive support, in the electrolyte, or both;

wherein the cocatalyst is bound to the aldehyde, ketone or alcohol functionality of the reaction intermediate, thereby activating it for further reaction with the electrocatalyst;

(b) Bringing the anode and the cathode into conductive contact with an external current source;

(c) Providing a flowing source of carbon dioxide to the cathode; and

(d) An electrical current is applied to drive an electrolytic reaction that produces electrons at the anode that are delivered to the cathode to produce an oxygenated hydrocarbon product from carbon dioxide, and the electrocatalyst and the cocatalyst are selected such that the oxygenated hydrocarbon product produced is selected from the group consisting of carbohydrates, carboxylic acids, aldehydes, ketones, and mixtures of two or more thereof.

20. The method of claim 19, wherein the promoter comprises a metal selected from the group consisting of Cu, ag, au, zn and intermetallic compounds thereof.

21. The method of claim 20, wherein the co-catalytic metal or intermetallic compound is in the form of a nanoparticle.

22. The combination of claim 1 wherein the CO-catalyst binds to a reactive intermediate on the electrocatalyst surface or in solution and 1) affects the binding orientation of the intermediate, and/or 2) activates the intermediate for subsequent hydrogenation or other CO with the binding surface ₂ Reaction of the CO reaction intermediate, and/or 3) influence the binding strength of the intermediate to become stronger or weaker, and/or 4) promote the formation of new reaction intermediates on the surface.

23. The combination of claim 1 wherein the promoter comprises a metal selected from the group consisting of Cu, ag, au, zn and intermetallic compounds thereof.

24. The combination of claim 23, wherein the co-catalytic metal or intermetallic compound is in the form of nanoparticles.

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