US20210207276A1 - Gas diffusion electrode for carbon dioxide utilization, method for producing same, and electrolytic cell having a gas diffusion electrode - Google Patents
Gas diffusion electrode for carbon dioxide utilization, method for producing same, and electrolytic cell having a gas diffusion electrode Download PDFInfo
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- US20210207276A1 US20210207276A1 US17/251,785 US201917251785A US2021207276A1 US 20210207276 A1 US20210207276 A1 US 20210207276A1 US 201917251785 A US201917251785 A US 201917251785A US 2021207276 A1 US2021207276 A1 US 2021207276A1
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- 238000009792 diffusion process Methods 0.000 title claims abstract description 105
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
- C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
- C25B11/031—Porous electrodes
- C25B11/032—Gas diffusion electrodes
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
- C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
- C25B11/031—Porous electrodes
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
- C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
- C25B11/061—Metal or alloy
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
- C25B11/095—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one of the compounds being organic
Definitions
- the present invention relates to a gas diffusion electrode for utilization of carbon dioxide and also a process for producing a gas diffusion electrode.
- the invention further relates to an electrolysis system having a corresponding gas diffusion electrode.
- a natural degradation of carbon dioxide occurs, for example, by means of photosynthesis.
- carbon dioxide is converted into carbohydrates in a process divided into many substeps over time and spatially on a molecular level.
- this process cannot readily be carried over to an industrial scale.
- a copy of the natural photosynthesis process using industrial photocatalysis has hitherto not been sufficiently efficient.
- a further method is the electrochemical reduction of carbon dioxide.
- Systematic studies on the electrochemical reduction of carbon dioxide are still a relatively young field of development. Only since a few years ago have efforts been made to develop an electrochemical system which can reduce an acceptable amount of carbon dioxide.
- GDE Gas diffusion electrodes
- a typical problem occurring in the case of gas diffusion electrodes used for CO 2 reduction which are in contact with an electrolyte is that of avoiding undesirable secondary reactions in the electrolyte-side region of the gas diffusion electrode.
- the gas diffusion electrode has to ensure sufficient supply of CO 2 and the respective electrolyte to the catalytically active sites by means of gas and ion transport.
- gas diffusion electrodes produced in this way tend to have the limiting pore diameter only within the gas diffusion electrode but not on the surface.
- the pore size diameter facing the electrolyte side is comparatively large compared to gas diffusion electrodes having a gas diffusion layer, so that undesirable flooding behavior of the pore system is observed.
- gas diffusion electrodes having large pore openings or a low hydrophobicity display strong electrolyte permeation through the respective gas diffusion electrode. The permeation is controlled by the electric field gradient, i.e. electroosmosis. This effect leads to an undesirable decrease in the Faraday efficiency of the gaseous products CO or ethylene.
- the gas diffusion electrode of the invention is used for the utilization of carbon dioxide and comprises a metallic support and an electrically conductive catalyst layer which has been applied to this metallic support and has hydrophilic pores and/or channels and hydrophobic pores and/or channels.
- the catalyst layer comprises metallic particles and a first polymeric binder material, wherein a porous gas diffusion layer containing the first polymeric binder material has been formed on the surface of the catalyst layer.
- the polymeric gas diffusion layer formed on the surface (the side of the catalyst layer or the gas electrode facing the electrolyte in an electrolysis cell) of the catalyst layer represents the reaction zone outside the gas diffusion electrode which is in contact with the reactants, in particular CO 2 and the electrolyte.
- the gas diffusion layer here sets the limiting pore diameter for the total gas diffusion electrode. Both the degree of hydrophobicity and the pore size of the gas diffusion layer can be controlled via targeted selection of the binder material used, the size of the metallic, catalytically active particles and the parameters in the production process for the gas diffusion electrode.
- the gas diffusion layer advantageously has a porosity of more than 70%.
- the thickness of the gas diffusion layer is advantageously in the range from 150 ⁇ m to 500 ⁇ m.
- the thickness of the catalyst layer is advantageously in the range from 5 nm to 500 nm.
- the differential pressure based on passage of a fluid medium through the catalyst layer and also the hydrostatic pressure based on passage of a fluid medium through the outer layer can be influenced or set via such a catalyst layer.
- a fluoropolymer is advantageously used as first polymeric binder material.
- first polymeric binder material from 3% by weight to 15% by weight of the first polymeric binder material is used.
- PVDF polyvinylidene fluoride
- the first polymeric binder material is advantageously embedded partly within the pores and/or channels of the catalyst layer.
- a hydrophobic “subnetwork” is additionally formed within the pores of the catalyst layer, which increases the hydrophobicity of the catalyst layer and thus the gas diffusion electrode overall.
- the differential pressure based on passage of a fluid medium through the gas diffusion layer and also the hydrostatic pressure based on passage of a fluid medium through the gas diffusion layer can be influenced or set via such a gas diffusion layer.
- the differential pressure based on passage of a fluid medium through the gas diffusion layer is in the range from 20 mbar to 220 mbar, in particular in the range from 60 mbar to 200 mbar.
- the hydrostatic pressure based on passage of a fluid medium through the gas diffusion layer is advantageously in the range from 20 mbar to 1000 mbar and in particular in the range from 200 mbar to 1000 mbar.
- the pore size of the catalyst layer is advantageously in the range from 0.3 ⁇ m to 5 ⁇ m.
- the pore size of the catalyst layer is particularly advantageously in the range from 2 ⁇ m to 3 ⁇ m.
- the particle size of the metallic particles is advantageously in the range from 500 nm to 5 ⁇ m and particularly advantageously in the range from 2 ⁇ m to 3 ⁇ m.
- the metallic particles are advantageously precoated at least in subregions with a second polymeric binder material. This increases the hydrophobicity of the gas diffusion electrode further.
- second polymeric binder material binder polymer
- advantage is given to using PTFE (polytetrafluoroethylene).
- metallic particles advantage is given to using silver particles.
- the use of copper particles or other catalytically active particles is also possible.
- the metallic particles used are advantageously coated at least in subregions with the first polymeric binder material.
- the metallic support is advantageously configured as a metallic gauze (or a corresponding sheet-like structure made of wire).
- the material of the support is advantageously matched to the metallic particles used.
- a silver gauze is advantageously used as metallic support.
- the gas diffusion electrode is particularly advantageously made by means of an extraction process. This process makes growth of the desired thin gas diffusion layer on the surface of the catalyst layer of the gas diffusion electrode possible.
- the process of the invention serves to produce a gas diffusion electrode for utilization of CO 2 .
- the process comprises mixing of metallic particles with a first binder material to form a suspension, application of the suspension to a metallic support and introduction of the metallic support loaded with the suspension into a precipitation bath to form an electrically conductive catalyst layer.
- a porous gas diffusion layer containing the first polymeric binder material is formed on the surface of the catalyst layer within the precipitation bath.
- the above-described process is an extraction process (“inversion casting” process, phase inversion).
- Manufacture of the gas diffusion electrode by means of this process makes it possible for a thin gas diffusion layer whose pore diameter is limiting for the total gas diffusion electrode to be produced on the surface of the catalyst layer.
- the first binder material, the size of the metallic, catalytically active particles and the parameters in the production process for the gas diffusion electrode influence the degree of hydrophobicity and also the pore size of the gas diffusion layer.
- the gas diffusion electrode can be made smaller since a greater differential pressure through the gas diffusion electrode is less sensitive to the hydrostatic pressure of the electrolyte.
- the production of the gas diffusion electrode is associated with a smaller outlay since one process step, namely activation of the electrode (oxidation of additional metal oxides), can be omitted.
- the metallic particles can be used directly.
- a further advantage is that the gas diffusion electrode is simpler to integrate into electrolysis systems because of the decreased passage of electrolyte compared to conventional electrodes.
- a mixture of water and isopropanol is advantageously used as precipitation bath.
- This mixture represents a “nonsolvent” for the polymeric binder materials and as a result of diffusion brings about exchange of solvent and nonsolvent and thus phase separation.
- the first polymeric binder material solidifies here and forms the gas diffusion layer on the surface of the catalyst layer.
- the electrolysis cell of the invention comprises a gas diffusion electrode as per one of the above-described embodiments.
- the gas diffusion electrode is advantageously used as cathode here.
- the electrolysis cell is advantageously configured on the cathode side for the reduction of carbon dioxide.
- the further constituents of the electrolysis cell for instance the anode, optionally one or more membranes, feed conduit(s) and discharge conduit(s), the voltage source and further optional facilities such as cooling or heating devices, are essentially variable for the purposes of the invention.
- the anolytes and/or catholytes which are used in such an electrolysis cell.
- FIG. 1 a schematic depiction of a section of a gas diffusion electrode made by means of an extraction process
- FIG. 2 a schematic depiction of a section of a gas diffusion electrode made by means of a calendering process
- FIG. 3 a section of the gas diffusion electrode of FIG. 2 .
- FIG. 4 a further section of the gas diffusion electrode of FIG. 2 .
- FIG. 1 shows a schematic depiction of a section of a gas diffusion electrode 1 produced by means of an extraction process.
- a suspension comprising metallic particles 3 and a first polymeric binder material 5 is applied to a metallic support 7 (merely indicated by an arrow).
- the first binder material 5 solidifies and forms a gas diffusion layer 9 on the surface 11 of the catalyst layer 13 of the gas diffusion electrode 1 .
- FIG. 2 shows a section of a gas diffusion electrode 21 produced by means of a calendering process.
- the reaction of the CO 2 additionally takes place in the electrolyte 17 , which leads to undesirable secondary reactions.
- the gas diffusion electrode 21 has larger pores in the surface, so that there is a risk of undesirable flooding of the gas diffusion electrode 21 .
- FIGS. 3 and 4 each show corresponding sections 25 , 27 of the 2-phase reactions (section 25 ) and the 3-phase reactions (section 27 ) as per FIG. 2 .
- FIG. 3 shows a 2-phase reaction. This takes place within the electrolyte 17 and leads, as indicated above, to undesirable secondary products.
- FIG. 3 shows a 3-phase reaction in which a reaction of CO 2 occurs within the gas diffusion layer 9 of the gas diffusion electrode 1 .
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- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
Description
- This application is the US National Stage of International Application No. PCT/EP2019/064572 filed 5 Jun. 2019, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 10 2018 210 457.3 filed 27 Jun. 2018. All of the applications are incorporated by reference herein in their entirety.
- The present invention relates to a gas diffusion electrode for utilization of carbon dioxide and also a process for producing a gas diffusion electrode. The invention further relates to an electrolysis system having a corresponding gas diffusion electrode.
- At present, about 80% of worldwide energy consumption is covered by the combustion of fossil fuels. About 34000 million metric tons of the greenhouse gas carbon dioxide (CO2) are emitted into the atmosphere via these combustion processes every year worldwide. The major part of carbon dioxide is disposed of via this liberation into the atmosphere (in the case of large brown coal power stations more than 50000 t per day).
- Owing to the increasing scarcity of fossil fuel resources and the volatile availability of renewable energy sources, research into the reduction of CO2 is becoming of ever greater interest. Here, CO2 emissions are decreased and the CO2 could be utilized as inexpensive carbon source.
- The discussion regarding the adverse effects of CO2 on the climate has led to reutilization of CO2 being considered. However, CO2 is thermodynamically in a very low position and can therefore be reduced again to give usable products only with difficulty.
- A natural degradation of carbon dioxide occurs, for example, by means of photosynthesis. Here, carbon dioxide is converted into carbohydrates in a process divided into many substeps over time and spatially on a molecular level. However, this process cannot readily be carried over to an industrial scale. A copy of the natural photosynthesis process using industrial photocatalysis has hitherto not been sufficiently efficient.
- A further method is the electrochemical reduction of carbon dioxide. Systematic studies on the electrochemical reduction of carbon dioxide are still a relatively young field of development. Only since a few years ago have efforts been made to develop an electrochemical system which can reduce an acceptable amount of carbon dioxide.
- Electrolysis systems having gas diffusion electrodes have now been used to an increased extent for this purpose. These systems usually consist of a cathode space and an anode space. To achieve an effective conversion of the CO2 used, the cathode is ideally configured as porous gas diffusion electrode. Gas diffusion electrodes (GDE) are porous electrodes in which liquid, solid and gaseous phases are present and the electrically conductive catalyst catalyzes the electrochemical reaction between the liquid phase and the gaseous phase.
- A typical problem occurring in the case of gas diffusion electrodes used for CO2 reduction which are in contact with an electrolyte (for example KHCO3, K2SO4, KOH or mixtures thereof) is that of avoiding undesirable secondary reactions in the electrolyte-side region of the gas diffusion electrode. Here, the gas diffusion electrode has to ensure sufficient supply of CO2 and the respective electrolyte to the catalytically active sites by means of gas and ion transport.
- Gas diffusion electrodes are frequently produced by means of a roller calendering process as is also disclosed in U.S. Pat. No. 2,013,010 190 6 A1. Here, the catalytically active metallic particles used for forming the gas diffusion electrode are mixed with hydrophobic particles such as PTFE, the resulting mixture is applied to a metallic support and arranged between two PTFE films before being calendered. The shear force enables the PTFE to flow and a network of PTFE binds the catalytically active particles together. The porosity and to a certain extent also the pore size can be modified via the compression force and the particle size.
- However, gas diffusion electrodes produced in this way tend to have the limiting pore diameter only within the gas diffusion electrode but not on the surface. The pore size diameter facing the electrolyte side is comparatively large compared to gas diffusion electrodes having a gas diffusion layer, so that undesirable flooding behavior of the pore system is observed. Furthermore, gas diffusion electrodes having large pore openings or a low hydrophobicity display strong electrolyte permeation through the respective gas diffusion electrode. The permeation is controlled by the electric field gradient, i.e. electroosmosis. This effect leads to an undesirable decrease in the Faraday efficiency of the gaseous products CO or ethylene.
- It is therefore an object of the invention to provide a possibility for electrochemical utilization of CO2 which is more efficient compared to the prior art.
- This object is achieved according to the invention by the features of the independent claims. Advantageous embodiments of the invention are set forth in the dependent claims and the following description.
- The gas diffusion electrode of the invention is used for the utilization of carbon dioxide and comprises a metallic support and an electrically conductive catalyst layer which has been applied to this metallic support and has hydrophilic pores and/or channels and hydrophobic pores and/or channels. The catalyst layer comprises metallic particles and a first polymeric binder material, wherein a porous gas diffusion layer containing the first polymeric binder material has been formed on the surface of the catalyst layer.
- The polymeric gas diffusion layer formed on the surface (the side of the catalyst layer or the gas electrode facing the electrolyte in an electrolysis cell) of the catalyst layer represents the reaction zone outside the gas diffusion electrode which is in contact with the reactants, in particular CO2 and the electrolyte.
- The gas diffusion layer here sets the limiting pore diameter for the total gas diffusion electrode. Both the degree of hydrophobicity and the pore size of the gas diffusion layer can be controlled via targeted selection of the binder material used, the size of the metallic, catalytically active particles and the parameters in the production process for the gas diffusion electrode.
- The gas diffusion layer advantageously has a porosity of more than 70%. The thickness of the gas diffusion layer is advantageously in the range from 150 μm to 500 μm.
- The thickness of the catalyst layer is advantageously in the range from 5 nm to 500 nm. The differential pressure based on passage of a fluid medium through the catalyst layer and also the hydrostatic pressure based on passage of a fluid medium through the outer layer can be influenced or set via such a catalyst layer.
- A fluoropolymer is advantageously used as first polymeric binder material. In particular, from 3% by weight to 15% by weight of the first polymeric binder material is used. The use of polyvinylidene fluoride (PVDF) is particularly advantageous here. This polymer allows formation of the desired outer layer in the production of the gas diffusion electrode.
- In addition, the first polymeric binder material is advantageously embedded partly within the pores and/or channels of the catalyst layer. In this way, a hydrophobic “subnetwork” is additionally formed within the pores of the catalyst layer, which increases the hydrophobicity of the catalyst layer and thus the gas diffusion electrode overall.
- The differential pressure based on passage of a fluid medium through the gas diffusion layer and also the hydrostatic pressure based on passage of a fluid medium through the gas diffusion layer can be influenced or set via such a gas diffusion layer. The differential pressure based on passage of a fluid medium through the gas diffusion layer is in the range from 20 mbar to 220 mbar, in particular in the range from 60 mbar to 200 mbar. The hydrostatic pressure based on passage of a fluid medium through the gas diffusion layer is advantageously in the range from 20 mbar to 1000 mbar and in particular in the range from 200 mbar to 1000 mbar.
- The pore size of the catalyst layer is advantageously in the range from 0.3 μm to 5 μm. The pore size of the catalyst layer is particularly advantageously in the range from 2 μm to 3 μm. The particle size of the metallic particles is advantageously in the range from 500 nm to 5 μm and particularly advantageously in the range from 2 μm to 3 μm.
- The metallic particles are advantageously precoated at least in subregions with a second polymeric binder material. This increases the hydrophobicity of the gas diffusion electrode further. As second polymeric binder material (binder polymer), advantage is given to using PTFE (polytetrafluoroethylene). As metallic particles, advantage is given to using silver particles. The use of copper particles or other catalytically active particles is also possible. The metallic particles used are advantageously coated at least in subregions with the first polymeric binder material.
- The metallic support is advantageously configured as a metallic gauze (or a corresponding sheet-like structure made of wire). Here, the material of the support is advantageously matched to the metallic particles used. A silver gauze is advantageously used as metallic support.
- The gas diffusion electrode is particularly advantageously made by means of an extraction process. This process makes growth of the desired thin gas diffusion layer on the surface of the catalyst layer of the gas diffusion electrode possible.
- The process of the invention serves to produce a gas diffusion electrode for utilization of CO2. The process comprises mixing of metallic particles with a first binder material to form a suspension, application of the suspension to a metallic support and introduction of the metallic support loaded with the suspension into a precipitation bath to form an electrically conductive catalyst layer. A porous gas diffusion layer containing the first polymeric binder material is formed on the surface of the catalyst layer within the precipitation bath.
- The above-described process is an extraction process (“inversion casting” process, phase inversion). Manufacture of the gas diffusion electrode by means of this process makes it possible for a thin gas diffusion layer whose pore diameter is limiting for the total gas diffusion electrode to be produced on the surface of the catalyst layer. Here, the first binder material, the size of the metallic, catalytically active particles and the parameters in the production process for the gas diffusion electrode influence the degree of hydrophobicity and also the pore size of the gas diffusion layer.
- Furthermore, an intensive connection between the metallic particles and the binder materials used is achieved by means of the extraction process, as a result of which the mechanical stability of the gas diffusion electrode is improved compared to conventional gas diffusion electrodes.
- The production of “tailored” gas diffusion layers on the surface of the catalyst layer of gas diffusion electrodes is particularly advantageous because the Faraday efficiency is improved as a result of the reduced risk of flooding of the gas diffusion electrode and thus two-phase secondary reactions such as evolution of hydrogen are reduced.
- Furthermore, the gas diffusion electrode can be made smaller since a greater differential pressure through the gas diffusion electrode is less sensitive to the hydrostatic pressure of the electrolyte.
- In addition, the production of the gas diffusion electrode is associated with a smaller outlay since one process step, namely activation of the electrode (oxidation of additional metal oxides), can be omitted. The metallic particles can be used directly.
- A further advantage is that the gas diffusion electrode is simpler to integrate into electrolysis systems because of the decreased passage of electrolyte compared to conventional electrodes.
- A mixture of water and isopropanol is advantageously used as precipitation bath. This mixture represents a “nonsolvent” for the polymeric binder materials and as a result of diffusion brings about exchange of solvent and nonsolvent and thus phase separation.
- The first polymeric binder material solidifies here and forms the gas diffusion layer on the surface of the catalyst layer.
- The advantages and advantageous embodiments described for the gas diffusion electrode of the invention apply equally to the process of the invention and can accordingly be carried over analogously to this.
- The electrolysis cell of the invention comprises a gas diffusion electrode as per one of the above-described embodiments. The gas diffusion electrode is advantageously used as cathode here. The electrolysis cell is advantageously configured on the cathode side for the reduction of carbon dioxide.
- The further constituents of the electrolysis cell, for instance the anode, optionally one or more membranes, feed conduit(s) and discharge conduit(s), the voltage source and further optional facilities such as cooling or heating devices, are essentially variable for the purposes of the invention. The same applies to the anolytes and/or catholytes which are used in such an electrolysis cell.
- Overall, the use of a gas diffusion electrode according to the invention in an appropriate electrolysis system or in an electrolysis cell leads to greater efficiency of the electrochemical system and thus makes the end product more competitive. This is additionally supported by the corresponding process according to the invention for producing the gas diffusion electrode.
- Working examples of the invention are explained in more detail below with the aid of a drawing. The drawing shows:
-
FIG. 1 a schematic depiction of a section of a gas diffusion electrode made by means of an extraction process, -
FIG. 2 a schematic depiction of a section of a gas diffusion electrode made by means of a calendering process, -
FIG. 3 a section of the gas diffusion electrode ofFIG. 2 , and -
FIG. 4 a further section of the gas diffusion electrode ofFIG. 2 . -
FIG. 1 shows a schematic depiction of a section of a gas diffusion electrode 1 produced by means of an extraction process. To this end, a suspension comprisingmetallic particles 3 and a firstpolymeric binder material 5 is applied to a metallic support 7 (merely indicated by an arrow). As a result of phase inversion (dipping of the coated metallic support 7 into a “non” solvent), thefirst binder material 5 solidifies and forms a gas diffusion layer 9 on the surface 11 of the catalyst layer 13 of the gas diffusion electrode 1. - The reaction between a
gaseous reactant 15, in the present case CO2, and theelectrolyte 17 then takes place at themetallic particles 3 in this gas diffusion layer 9. This is in the present case a 3-phase reaction in which a conversion of CO2 into CO occurs at the phase boundary 19 between themetallic particles 3 in the gas diffusion layer 9, the CO2 and the electrolyte 17 (see alsoFIG. 4 ). - In a likewise schematic depiction,
FIG. 2 shows a section of agas diffusion electrode 21 produced by means of a calendering process. Here, the reaction of the CO2 additionally takes place in theelectrolyte 17, which leads to undesirable secondary reactions. Owing to the production process, thegas diffusion electrode 21 has larger pores in the surface, so that there is a risk of undesirable flooding of thegas diffusion electrode 21. -
FIGS. 3 and 4 eachshow corresponding sections FIG. 2 .FIG. 3 shows a 2-phase reaction. This takes place within theelectrolyte 17 and leads, as indicated above, to undesirable secondary products.FIG. 3 shows a 3-phase reaction in which a reaction of CO2 occurs within the gas diffusion layer 9 of the gas diffusion electrode 1. - The advantages and particular embodiments described for the gas diffusion electrode of the invention and the process of the invention apply equally to the electrolysis cell of the invention and can accordingly be carried over analogously to this.
-
-
- 1 Gas diffusion electrode
- 3 Metallic particles
- 5 Polymeric binder material
- 7 Metallic support
- 9 Outer layer
- 11 Catalyst surface
- 13 Catalyst layer
- 15 Reactant
- 17 Electrolyte
- 18 Outer layer
- 19 Phase boundary
- 21 Gas diffusion electrode
- 25 Section of gas diffusion electrode
- 27 Section of gas diffusion electrode
Claims (13)
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DE102018210457.3A DE102018210457A1 (en) | 2018-06-27 | 2018-06-27 | Gas diffusion electrode for carbon dioxide utilization, process for its production and electrolysis cell with gas diffusion electrode |
DE102018210457.3 | 2018-06-27 | ||
PCT/EP2019/064572 WO2020001944A1 (en) | 2018-06-27 | 2019-06-05 | Gas diffusion electrode for carbon dioxide utilization, method for producing same, and electrolytic cell having a gas diffusion electrode |
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US20210207276A1 true US20210207276A1 (en) | 2021-07-08 |
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US (1) | US20210207276A1 (en) |
EP (1) | EP3788183A1 (en) |
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CN113789538A (en) * | 2021-11-15 | 2021-12-14 | 广东工业大学 | Gas diffusion cathode with suspension catalyst layer and electrochemical reactor |
CN115312788A (en) * | 2022-07-11 | 2022-11-08 | 北京大学 | Gas diffusion electrode capable of realizing phase conversion under normal temperature and light pressure as well as preparation method and application of gas diffusion electrode |
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- 2018-06-27 DE DE102018210457.3A patent/DE102018210457A1/en active Pending
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- 2019-06-05 US US17/251,785 patent/US20210207276A1/en active Pending
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CN115312788A (en) * | 2022-07-11 | 2022-11-08 | 北京大学 | Gas diffusion electrode capable of realizing phase conversion under normal temperature and light pressure as well as preparation method and application of gas diffusion electrode |
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DE102018210457A1 (en) | 2020-01-02 |
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