System and method for converting co2 to formaldehyde

Abstract

A system and method for the production of formaldehyde from electrocatalytically generated formic acid can include using a highly energy efficient electro-catalytic conversion step for producing aqueous formic acid, combined with a thermocatalytic reaction step to produce formaldehyde.

Description

Attorney Docket No.: 315812-00048 PATENTSYSTEM AND METHOD FOR CONVERTING CO2 TO FORMALDEHYDECROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Application No. 63 / 730,994, filed December 12, 2024 and titled “SYSTEM AND METHOD FOR CONVERTING CO2 TO FORMALDEHYDE”, the disclosure of which is hereby incorporated by reference in its entirety.FIELD

[0002] The presently disclosed technology relates generally to the production of sustainable formaldehyde from carbon dioxide (CO2) by a combination of electrochemical and thermochemical / non-electrochemical catalysis as a platform for renewable plastics, resins, and / or fuels.BACKGROUND

[0003] The increased awareness of the adverse effects of carbon dioxide (CO2) emission accumulating in the atmosphere due to the slow biologic re-fixation rate means that new processes for converting / mitigating CO2 emission are being sought with increasing impetus.

[0004] The current commercial method of reducing CO2 emission is underground sequestration. In contrast, novel processes are needed that convert the CO2 emissions into products needed by industry or consumers. Catalytic processes reduce the energy input needed to convert one or more feedstocks into products of interest such as precursors for plastics. Particularly, catalysis may allow for certain products to be favored over others.

[0005] CO2 conversion is thermodynamically challenging as it means the conversion from a thermodynamic sink (lowest thermodynamic energy form of carbon) into a higher energy state, which inherently means it requires significant energy input to proceed. Excessive energy input into a reaction will allow a multitude of reaction products to be accessible with no way to direct the reaction. The use of catalytic conversion of CO2 is therefore the most promising way to reduce energy inputs needed and simultaneously achieve reaction to only one or a few reaction products of interest.

[0006] Prior art has shown that CO2 and hydrogen can be converted to formaldehyde with good selectivity only using a ruthenium on calcium layered double hydroxide (LDH) by employing intermediate pressures of 10 bar and temperatures from 30-80 degrees Celsius, where it is argued that formic acid may be a reaction intermediate — see Lidan Deng, et al., Catalytic aqueous CO2Attorney Docket No.: 315812-00048 PATENT reduction to formaldehyde at Ru surface on hydroxyl-groups-rich LDH under mild conditions, Applied Catalysis B: Environmental, Volume 322, 2023, 122124, ISSN 0926-3373, which is hereby incorporated by reference. The prior art has also shown the conversion of formic acid to formaldehyde by applying relatively higher temperature through thermal hydrogenation of CO2 - or biomass -derived formic acid - using metal oxides, specifically CeCE or TeCE oxides and temperatures most preferably from 60-100 degrees Celsius — see U.S. Patent No. 9.193,593 B2, which is hereby incorporated by reference. The prior art has taught a system for producing formic acid from CO2 by thermochemical hydrogenation using molecular hydrogen (H2). The obtained reaction crude is then purified using electro-dialysis to remove the charged formic acid. In one embodiment a generic conversion module is described for hydrogenation of formic acid to formaldehyde using a Pd based catalyst — see U.S. Publication No. 2024 / 0228419 Al, which is hereby incorporated by reference.

[0007] Commercial processes for conversion of CO2 are currently limited to methanation reactions, and the production of syngas, urea, and methanol. Electrocatalytic formic acid production relies on catalysts with high energy barriers, called overpotentials, due to the use of metals (e.g. tin and bismuth-based materials) that require large driving forces to overcome the barrier for the initial reaction step involving electron transfer to CO2. Additionally, the stability of the aforementioned metals is limited — the extended lifetime needed for industrial applications for has not yet been demonstrated.SUMMARY

[0008] The presently disclosed technology addresses the above and other drawbacks of the prior art, as explained below.

[0009] The recent development of highly energy efficient electrocatalysts for CO2 reduction to formic acid or formate with reaction starting at overpotentials lower than 600 mV vs. the reversible hydrogen electrode (RHE) has enabled the cost-efficient production of formic acid for processing to products, such as chemicals and fuels described herein. See Laursen AB, Calvinho KUD, Goetjen TA, Yap KMK, Hwang S, Yang H, Garfunkel E, Dismukes GC (2021) CO2 electro-reduction on Cu3P: Role of Cu(I) oxidation state and surface facet structure in Cl- formate production and H2 selectivity. Electrochimica Acta, 391:138889; Calvinho KUD, Laursen AB, Yap KMK, Goetjen TA, Hwang S, Murali N. Mejia-Sosa B, Lubarski A, Teeluck KM, Hall ES, Garfunkel E, Greenblatt M, Dismukes GC (2018) Selective CO2 reduction to C3Attorney Docket No.: 315812-00048 PATENT and C4 oxyhydrocarbons on nickel phosphides at overpotentials as low as 10 mV. Energy & Environmental Science, 11(9):2550— 2559; and Kortlever R, Peters I, Koper S, Koper MTM (2015) Electrochemical CO2 Reduction to Formic Acid at Low Overpotential and with High Faradaic Efficiency on Carbon-Supported Bimetallic Pd-Pt Nanoparticles. ACS Catalysis, 5(7):3916-3923, each of which are hereby incorporated by reference.

[0010] Recent developments of low temperature formic acid to formaldehyde reaction catalysts based on ruthenium on layered double hydroxide support (LDH support) also enabled the discovery of the novel processes described herein utilizing a range of supports with a defined ruthenium nanoparticle catalyst size range. Unfortunately, this process showed reaction rates that are still several orders of magnitude below what is required for commercialization. It should be noted that the above results have not been reproducible based on the description in the prior art.

[0011] The need for the production of sustainable chemicals and fuels is rapidly increasing and novel solutions are needed. This need, together with the advent of cheap renewable electricity allows the economic production of chemicals and fuels from CO2 giving these products a competitive market advantage.

[0012] In one embodiment, the presently disclosed technology utilizes recent developments in electrocatalytic CO2 reduction to a reactive aldehyde, such as formaldehyde, which can be utilized as a platform chemical for producing a variety of products, such as but not limited to alcohols, glycols such as ethylene glycol and propylene glycol, monomers, resins, polyols, plastics, polyoxymethylene, polyesters, and / or sustainable fuels.

[0013] In another embodiment, the presently disclosed technology is directed to a system and method for the production of formaldehyde from electrocatalytically generated formic acid that can include using a combination of a highly energy efficient electro-catalytic conversion step for producing aqueous formic acid, combined with a thermally driven catalytic reaction step to produce formaldehyde.

[0014] In yet another embodiment, the presently disclosed technology is directed to a method for the production of a quantity of formaldehyde from a quantity of carbon dioxide. The method can include the step of electrochemically reducing the quantity of carbon dioxide, thereby providing a quantity of formic acid. The method can include the step of thermocatalytically reducing the formic acid formed to generate the quantity of formaldehyde. Optionally, the step of electrochemically reducing the quantity of carbon dioxide can be done in an energy efficientAttorney Docket No.: 315812-00048 PATENT manner. Optionally, the step of electrochemically reducing the quantity of carbon dioxide can be done in an aqueous solution. Optionally, wherein the quantity of formic acid is a quantity of aqueous formic acid. Optionally wherein the quantity of aqueous formic acid is in the form of the corresponding formate salt, e.g. potassium formate.BRIEF DESCRIPTION OF THE DRAWINGS:

[0015] The foregoing summary, as well as the following detailed description of the presently disclosed technology, will be better understood when read in conjunction with the appended drawings, wherein like numerals designate like elements throughout. For the purpose of illustrating the presently disclosed technology, there are shown in the drawings various illustrative embodiments. It should be understood, however, that the presently disclosed technology is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0016] Fig. 1 shows a high-level process diagram of the process innovation.

[0017] Fig. 2 shows a schematic process flow diagram of embodiment 1 of this innovation.

[0018] Fig. 3 shows a schematic process flow diagram of embodiment 2 of this innovation.

[0019] Fig. 4 shows a schematic process flow diagram of the additional process steps for production of fuels based on embodiment 1 & 2 of this innovation.

[0020] Fig. 5 shows a schematic process flow diagram of the additional process steps for production of ethylene glycol based on embodiment 1 & 2 of this innovation.

[0021] Fig. 6 shows another schematic process flow diagram of the additional process steps for production of fuels based on embodiment 1 & 2 of this innovation.

[0022] Fig. 7 shows a schematic electrochemical conversion cell for carbon dioxide reduction to formic acid and / or formate, wherein the electro-catalytic conversion is conducted in a cell with a solid electrolyte / membrane with cation exchange properties in direct contact with the cathode electrode according to one embodiment of the presently disclosed technology. The reduction to formic acid or formate is determined by the pH in the catholyte. They are not sequential reductions.

[0023] Fig. 8 shows a schematic electrochemical conversion cell for carbon dioxide reduction to formic acid and / or formate, wherein the electro -catalytic conversion is conducted in a cell with a solid electrolyte / membrane with cation exchange properties that is not in direct contact with the cathode electrode, thus there is a final gap between solid electrolyte and cathode in which aAttorney Docket No.: 315812-00048 PATENT supporting electrolyte containing liquid products and a catalytically inactive salt are re-circulated and from which product is obtained according to one embodiment of the presently disclosed technology. The gap allows a buffer solution layer, which can be beneficial in certain instances. In some embodiments, the size of the layer is a crucial optimization parameter. A zero-gap (i.e., no liquid layer) is preferential in certain instances.DETAILED DESCRIPTION

[0024] While systems, devices and methods are described herein by way of examples and embodiments, those skilled in the art recognize that the presently disclosed technology is not limited to the embodiments or drawings described. Rather, the presently disclosed technology covers all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims. Features of any one embodiment disclosed herein can be omitted or incorporated into another embodiment.

[0025] Any headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used herein, the word “may” is used in a permissive sense (i.e., meaning having the potential to) rather than the mandatory sense (i.e., meaning must). Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import.

[0026] The present invention describes a method for converting CO2 to formaldehyde and formaldehyde derived products using a two-step process that electrocatalytically reduces CO2 to formic acid / formate with high energy efficiency and the further reduction of formic acid / formate to formaldehyde using thermocatalysis.

[0027] The presently disclosed technology can produce a sustainable CO2 derived precursor for formaldehyde / formalin / paraformaldehyde for: 1) plastics such as polyoxymethylene, 2) formaldehyde adhesive resins, 3) ethylene glycol for poly-esters, 4) propylene glycol for de-icing and / or 5) oligomers of polyoxymethylene for the direct hydrodeoxygenation to fuels such as sustainable gasoline, sustainable aviation fuel, kerosene, and / or diesel / marine fuel.

[0028] Prior art describes the hydrogenation of CO2 to formaldehyde at intermediate pressures. These techniques suffer from very slow reaction rates, which are avoided in the presently disclosed technology by utilizing electrocatalytic formation of formic acid, which is rapid and can be done cost-effectively with cheap electricity and efficient catalysts. Prior art also describesAttorney Docket No.: 315812-00048 PATENT the reduction for formic acid using catalyst comprising Cerium or Tellurium oxides in a wide range of temperatures of 8-350 degrees Celsius, with 60-100 degrees Celsius being taught as most preferable.

[0029] In contrast, the presently disclosed technology utilizes formic acid produced by newly discovered and energy efficient formic acid reduction electrocatalysts not discovered at the time of the former invention with higher energy efficiency making the production of low cost formaldehyde and derivatives thereof economically viable.

[0030] Prior art separately describes the production of ethylene glycol from formaldehyde produced from methanol oxidation using homogenous catalysts (e,g„ U.S. Patent No. 7,615,671 B2, which is hereby incorporated by reference). In contrast the utilization of formaldehyde produced from energy efficient electrocatalytic formic acid allows a low carbon intensity process with market advantages not attainable from conventional formaldehyde sources such as methanol.

[0031] The process for producing CO2 derived formic acid electrochemically according to one embodiment of the presently disclosed technology can include the production of a product stream containing a supporting electrolyte, such as alkali metal earth bicarbonate, e.g. potassium bicarbonate typically in the concentration range of 0.1-0.5M.

[0032] In another embodiment of the presently disclosed technology, the process for producing CO2 derived formic acid salts electrochemically can include the use of potassium hydroxide anolyte and no supporting ionic catholyte production resulting in a product cathode stream containing a alkali metal earth bicarbonate, typically potassium bicarbonate typically in the concentration range of 0.1-3M and potassium formate in a concentration range of 0.01-3M.

[0033] One embodiment of the presently disclosed technology utilizes electrodialysis (ED), electrodeionization (EDI), or resin-wafer-EDI (RW-EDI) to remove the supporting electrolyte, which would otherwise interfere with the further reaction steps. In another embodiment, use of EDI / RW-EDI is optional due to the use of a zero gap electrolyzer with a proton conducting membrane for high concentration formic acid production, which reduces costs due to salt removal and costs for product concentration in subsequent steps.

[0034] In one embodiment, the presently disclosed technology includes a process for the production of sustainable formaldehyde from carbon dioxide (CO2) by a combination of electrochemical and thermochemical catalysis as a platform for renewable plastics, resins, and / orAttorney Docket No.: 315812-00048 PATENT fuels.

[0035] In one embodiment, the presently disclosed technology improves on previous inventions for the production of plastics and adhesive resins based on formaldehyde.

[0036] In one embodiment, the presently disclosed technology is directed to a method that utilizes hitherto unrealized low temperatures of 1-55 degrees Celsius for the hydrogenation of CO2 derived formic acid to formaldehyde using a supported ruthenium metal nanoparticle catalyst in the primary nanoparticle size range of 0.1-50 nm. The aspect of a ruthenium particle size requirement for the low temperature reaction has not been taught or even suggested in the prior art. Furthermore, the support for the ruthenium catalyst is not limited to layered Ca double hydroxide supports, which includes without being limited to Ca-phosphates such as hydroxyapatite.

[0037] In one embodiment, the presently disclosed technology is directed to the utilization of electrocatalysts for the production of formic acid that operate at low overpotentials, e.g., with very high energy efficiency. Examples include but are not limited to NizP (e.g., U.S. Publication No. 2023 / 0193481 Al, which is hereby incorporated by reference), Pd or alloys thereof (see R. Kortlever et al., Electrochemical CO2 Reduction to Formic Acid at Low Overpotential and with High Faradaic Efficiency on Carbon-Supported Bimetallic Pd-Pt Nanoparticles, ACS Catal. 2015, 5, 7, 3916-3923, which is hereby incorporated by reference), and / or Bismuth oxides.

[0038] Optionally, the presently disclosed technology utilizes higher energy efficiency and reaction production rates stemming from the combination of a facile 2 electron electrochemical conversion to formic acid followed by a low-temperature thermochemical reaction step (non- electrochemical). Together this reduces the energy consumption, reduces the side-product formation, and / or favors formation of methanediol (aqueous formaldehyde, also known as methylene glycol) thermodynamically.

[0039] In one optional embodiment, the presently disclosed technology is directed to a method for the production of drop-in replacement green products with a distinct market advantage due to the increased sustainability originating from being CO2 derived. The formed CO2 derived / sustainable formaldehyde can be used: A) directly for polyoxymethylene plastics or formaldehyde resins, and / or B) In another embodiment, the formaldehyde is further upgraded to ethylene glycol through hydroformylation using, for instance, heterogenous or homogenous precious metal catalysts, based on Rh and P (see, e.g., U.S. Patent No. 7,615,671 B2, which isAttorney Docket No.: 315812-00048 PATENT hereby incorporated by reference). In yet another embodiment, the formed formaldehyde is oligomerized into chains with a backbone of C4-C12 of oxygenated hydrocarbons for use in gasoline, Cs-Ci6 for use in sustainable aviation fuel, Jet A, C12-20 for use in sustainable diesel or sustainable marine fuel. After an additional hydrodeoxygenation step, the final drop-in replacement paraffin fuels can be obtained for blending or use directly as a sustainable fuel.

[0040] The discovery of an energy efficient conversion of formic acid to aqueous formaldehyde / methanediol, combined with newly discovered electrocatalysts for the production of formic acid at low overpotentials (low energy input), gives rise to the first-time possibility to realize an economically feasible and market favorable process for producing CO2 derived polymers, resins, and / or fuels from electro-catalytically CO2 derived formaldehyde.

[0041] The recent realization of abundant cheap electricity from renewable sources together with development of cheap and efficient carbon dioxide capture from various sources, such flue gas or even direct air capture, has spurred processes such as the presently disclosed technology that recycles carbon dioxide into chemicals and fuels, which can be competitive with conventional fossil fuel-based products.

[0042] In one embodiment of the presently disclosed technology, the process for producing formaldehyde from CO2 can be described as containing the following combination of reaction steps.

[0043] First - CO2 electrocatalytic reduction using low overpotentials, for instance using Ni2P:Mg, Pd-alloys, and / or Bi metal and / or Bi-oxides with feedstocks being CO2, water and electricity.

[0044] Second - optional formic acid purification from supporting electrolyte using Electrodeionization (EDI) or Resin Wafer Electrodeionization (RW-EDI).

[0045] Third - formic acid hydrogenation at low temperature to aqueous formaldehyde / methanediol using gaseous hydrogen at pressures from 10-200 bar, using a supported ruthenium nanoparticle catalyst.

[0046] Fourth - formaldehyde vacuum distillation, recirculation of unconverted formic acid and water.

[0047] Fifth - the sale of the obtained green formaldehyde for reason of polymer production, or, optional, starting from the Fourth step above, conversion of formaldehyde to ethylene glycol through thermocatalytic hydroformylation with CO and H2, through a one or two step reaction,Attorney Docket No.: 315812-00048 PATENT and / or optionally starting from the Fourth step, conversion of the formaldehyde to oxygenated hydrocarbon oligomers in the range of C6-C20 using a Lewis acid catalyst in aqueous solution.

[0048] Sixth - starting from the oxygenated hydrocarbon oligomers described in the fifth step above, hydrodeoxygenation of the oxygenated hydrocarbon oligomers in the presence of H2 to obtain a sustainable / CCL derived fuel using hydrodeoxygenation methods known in the field. Optionally, using a supported noble metal nanoparticle catalyst (e.g. Ru, Pd, Pt, Rh), a supported non noble metal Ni, Mo2C, nickel phosphide, or WC nanoparticle catalyst. The residual oxygen content and carbon-chain length determines the use for either gasoline, kerosene / sustainable aviation fuel, diesel, marine sustainable fuels, and / or blend-in fuels. Another novel aspect of the presently disclosed technology is that the hydrodeoxygenation can be conducted in a two-phase system using kerosene / aviation fuel / Diesel / cyclohexane or other apolar co-solvents, for example, for increasing the fuel production due to extraction of the sustainable fuel into the apolar cosolvent. In the presently disclosed process, this co-solvent is preferentially a fraction of the product stream recirculated into the hydrodeoxygenation step.

[0049] Seventh - starting from the Sixth step above, drying and / or water removal followed by optional fractionation to obtain final fuel fraction.

[0050] In one embodiment, low oxygen content is defined as less than 0.5% oxygen in aviation fuel. In another embodiment, low oxygen content is defined as less 12% oxygen in diesel.

[0051] While the presently disclosed technology has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. It is understood, therefore, that the presently disclosed technology is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the presently disclosed technology as defined by the appended claims.

Claims

Attorney Docket No.: 315812-00048 PATENTCLAIMSWhat is claimed is:

1. A method for the production of formaldehyde from electrocatalytically generated formic acid using a combination of a highly energy efficient electro-catalytic conversion step for producing aqueous formic acid, combined with a thermocatalytic reaction step to produce formaldehyde from the formic acid.

2. The method of claim 1, wherein the electro-catalytic conversion is conducted in a cell with a solid electrolyte / membrane with cation exchange properties in direct contact with the cathode electrode.

3. The method of claim 1, wherein the electro-catalytic conversion is conducted in a cell with a solid electrolyte / membrane with cation exchange properties that is not in direct contact with the cathode electrode.

4. The method of claim 3, wherein a finite gap between the solid electrolyte / membrane and the cathode electrode includes a supporting electrolyte containing liquid products and a catalytically inactive salt that are re-circulated and from which product is obtained.

5. The method of claim 2 or 3, wherein the supporting electrolyte is removed by electrochemical separation processes such as ED, EDI or RW-EDI.

6. The method of claim 2 or 3, further comprising: converting the formaldehyde to ethylene glycol using hydroformylation with CO and H2.

7. The method of claim 2 or 3, further comprising: converting oxygenated hydrocarbon to a low oxygen content fuel by hydrodeoxygenation in an aqueous phase.

8. The method of claim 1, further comprising: converting the formaldehyde to an oligomer with a carbon chain length of majorly C6-C20 oxygenated hydrocarbon.

9. A method of producing formaldehyde, the method comprising: electro-catalytically converting carbon dioxide to aqueous formic acid and through a thermocatalytic reaction producing formaldehyde, wherein the electro-catalytic conversion is conducted in a cell with a solidAttorney Docket No.: 315812-00048 PATENT electrolyte / membrane with cation exchange properties.

10. A method for the production of a quantity of formaldehyde from a quantity of carbon dioxide, the method comprising: electrochemically reducing the quantity of carbon dioxide, thereby providing a quantity of formic acid; and thermocatalytically reducing the formic acid formed to generate the quantity of formaldehyde.

11. The method of claim 10, wherein the step of electrochemically reducing the quantity of carbon dioxide is completed in an energy efficient manner.

12. The method of claim 10 or 11, wherein the step of electrochemically reducing the quantity of carbon dioxide occurs in an aqueous solution.

13. The method of claim 12, wherein the quantity of formic acid is a quantity of aqueous formic acid.

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