Anode-side cesium ion modified carbon dioxide electrocatalytic reduction system
By modifying the anode side with cesium ions and controlling the concentration and type of cesium ions, the problem of insufficient cation modification on the anode side in the existing technology is solved, and the high efficiency and stable performance of the carbon dioxide electroreduction system are achieved, making it suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUDAN UNIVERSITY
- Filing Date
- 2026-04-27
- Publication Date
- 2026-06-30
Smart Images
Figure CN122303914A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of carbon dioxide electrocatalytic reduction technology, specifically relating to a carbon dioxide electrocatalytic reduction system modified with cesium ions on the anode side. Background Technology
[0002] As a core direction of CCUS (Carbon Dioxide Electroreduction) technology, CO2 electroreduction can utilize renewable energy to convert CO2 into chemicals such as carbon monoxide, formic acid, ethylene, and ethanol. Its selective preparation has become a research hotspot. Silver-based and copper-based catalysts are the mainstream catalysts for the electrocatalytic reduction of CO2 to these products. Existing technologies improve the cathode performance of catalysts through methods such as flow cells and membrane electrode systems, while simultaneously improving the overall system efficiency through methods such as membrane electrode stack structure optimization and cathode electrolyte cation control.
[0003] Current research focuses primarily on the cathode side, including cathode catalyst structure design, control of cation types and concentrations in the cathode electrolyte, application of carbon dioxide reaction gas pressure at the cathode side, CO2 / CO ratio in the gas composition, and optimization of the cathode flow field. However, the impact of anode-side ion modification on the CO2 electroreduction process is generally neglected. In membrane electrode stacks, anion exchange membranes are commonly used for ion conduction, facilitating ion transfer between the anode and cathode. Cations at the anode undergo mass transfer across the membrane due to concentration differences and electromigration. Their types and concentrations directly affect the ion conduction efficiency within the membrane, thereby altering the local electric field distribution and cation enrichment state at the cathode interface, influencing the adsorption of reaction intermediates, and causing differences in product selectivity. Furthermore, electrolyte cations migrating to the cathode can react with CO2 to form carbonates, leading to blockage of active sites on the cathode catalyst and clogging of flow channels.
[0004] In existing technologies, the regulation of CO2 electroreduction mostly does not involve cations on the anode side. Some studies only adjust the concentration of the anode electrolyte in a simple way, without establishing a correlation mechanism between cation type, concentration, mass transfer parameters and cathode reduction performance, and without developing a corresponding precise regulation system. This leads to problems such as performance degradation and poor stability during the scale-up of membrane electrode stacks, which restricts the industrial application of CO2 electrocatalytic reduction technology.
[0005] Therefore, to precisely regulate cations on the anode side, a mechanism for regulating cation migration in the overall CO2 electroreduction system by modifying metal ions on the anode side should be established to address the shortcomings of existing technologies and improve the overall performance of the CO2 electrocatalytic reduction system. Summary of the Invention
[0006] This invention aims to solve the technical problems of neglecting cation modification on the anode side in existing carbon dioxide electroreduction technology, which leads to limited cathodic reduction performance, low system energy efficiency, and poor stability. It provides a carbon dioxide electrocatalytic reduction system modified with cesium ions on the anode side and its application.
[0007] The core innovation of this invention lies in the transmembrane regulatory mechanism of CO2 electroreduction by cesium ions modified on the anode side: cesium ion modification on the anode side affects the ion conduction efficiency of the anion exchange membrane under electromigration conditions, and the enriched cesium ions exhibit Donnan repulsion on the anode side (e.g., Figure 1 As shown), this effectively restricts cations from entering the anion exchange membrane, achieving the goal of controlling *COO2. - It stabilizes intermediate adsorption and inhibits hydrogen evolution side reactions and cathode flow channel salting-out.
[0008] The cesium ion-modified carbon dioxide electroreduction system on the anode side provided by this invention includes a membrane electrode stack, an anode electrolyte supply subsystem, a gas phase control subsystem, an electrochemical testing subsystem, and a main control module; wherein:
[0009] The membrane electrode stack body adopts a cathode flow channel-cathode gas diffusion electrode-ion exchange membrane-anode catalyst-anode flow channel arrangement structure. The cathode uses a commercially available metal catalyst (such as a silver catalyst with silver particle size of 60-120 nm), and the anode is a Ti felt supported on IrO2. The anode catalyst side is modified with cesium ions. An anion exchange membrane (such as Fumasep FAA-3-50, Sustanion X37-50 RT, MTCP-50, etc.) is placed between the cathode and anode to ensure ion conduction. The cesium ion-modified anode catalyst is the core control unit of this invention.
[0010] The anolyte supply subsystem is used to supply a specific type and concentration of anolyte to the anode side of the membrane electrode stack body. The anolyte exists in the form of a metal ion salt with a concentration range of 1×10⁻⁶. -4 mol / L to saturated solution;
[0011] The gas phase control subsystem is connected to the cathode side of the membrane electrode stack to realize the flow rate and pressure regulation of CO2 feed gas;
[0012] The electrochemical testing system includes a programmable constant current source and a product detection module. The programmable constant current source is used for the main electrolysis testing of the membrane electrode stack, and the product detection module detects the composition and content of the electroreduction products, realizing real-time parameter control and data acquisition.
[0013] The main control module enables real-time acquisition and feedback control of various parameters, ensuring the automated operation of the system.
[0014] Furthermore:
[0015] In the main body of the membrane electrode stack, the cesium ion modification on the anode side is achieved by physically spraying cesium ions onto both sides of the anode catalyst.
[0016] In the main body of the membrane electrode stack, the cesium ion-modified components on the anode side include: perfluorosulfonic acid cationic ionomer, cesium ion solution and binder; the binder is PTFE emulsion or FEPD 121.
[0017] In the main body of the membrane electrode stack, the cesium salt used for cesium ion modification on the anode side is selected from one or more of carbonates, bicarbonates, chlorides, bromides, iodides, sulfates, sulfites, phosphates, hydrogen phosphates, dihydrogen phosphates, nitrates, hydroxides, formates, acetates, oxalates, citrates, sulfonates, or their complex salts or mixed salts.
[0018] In the membrane electrode stack, the molar concentration of cesium ions modified with cesium ions on the anode side is 1 × 10⁻⁶. -6 A saturated solution with a concentration of mol / L, preferably 0.001-0.1 mol / L, more preferably 0.01-0.1 mol / L.
[0019] In the main body of the membrane electrode stack, the catalyst flow channel on the anode side is a parallel flow channel, the electrolyte is delivered by a plunger pump at a flow rate of 10-100 mL / min, and the temperature of the anode electrolyte is 25-100 ℃.
[0020] The cathode electrocatalyst is a metal-based catalyst, including one or more of the main metals such as gold, silver, copper, nickel, tin, bismuth, and zinc, as well as other metals such as indium, gallium, palladium, cobalt, and iron.
[0021] In the gas phase control subsystem, the CO2 feed gas flow rate is 0-200 sccm, and the cathode-side gas phase pressure is 1.0-2.5 bar.
[0022] Based on the above-described carbon dioxide electroreduction system, the present invention also provides an anode-side cation-modified carbon dioxide electroreduction operation, comprising the following steps:
[0023] Step 1, Prepare the anolyte: According to the target control requirements, dissolve the metal salt in deionized water, and adjust the metal ion concentration to 0.001 mol / L - saturated solution (preferably 0.01-0.1 mol / L) using the concentration adjustment component to obtain the anolyte and store it in the storage tank;
[0024] Step 2, System preheating and parameter initialization: Adjust the temperature of the anolyte to 25-100℃ using the temperature control component, introduce CO2 feed gas into the cathode side of the membrane electrode stack using the gas phase control subsystem, adjust the gas phase pressure to 1.0-2.5 bar, and set the initial current density of the programmable constant current source.
[0025] Step 3, Anode-side electrolyte control: The plunger pump pumps the anolyte into the anode-side channel of the membrane electrode stack at a flow rate of 10-100 mL / min. The main control module, based on the real-time data from the electrochemical testing subsystem, regulates the cation concentration, electrolyte flow rate, and electrolyte temperature through the concentration adjustment component, plunger pump, and temperature control component, respectively, to achieve dynamic regulation of the cations on the anode side.
[0026] Step 4, Electrocatalytic Reduction Reaction and Product Detection: The membrane electrode stack undergoes CO2 electrocatalytic reduction reaction under set parameters. The product detection module detects the cathode product in real time, and the main control module provides feedback on the cesium ion modification effect on the anode side based on the product detection results.
[0027] When it is necessary to improve the energy efficiency of the system, Cs can also be selected. + With Li + Na + K + The compound was used as an anode-side cation modification, Cs + / M + 1×10 -3 -1×10 3 .
[0028] This invention also provides the application of the cesium ion-modified carbon dioxide electroreduction system on the anode side in the electrocatalytic reduction of carbon dioxide to carbon monoxide. Specifically, this includes the industrial testing and production of its application in carbon dioxide electroreduction membrane electrode stacks, at speeds of 100-2000 mA / cm². 2 Within the current density range, the Faraday efficiency of CO remains above 80%, and at 500 mA / cm², it remains above 80%. 2 The stable operating time at current density is not less than 200 hours.
[0029] This invention involves cesium ion modification on the anode side. By adjusting the cesium ion concentration (0.001-0.1 mol / L), a correlation is established between the cesium ion concentration on the anode side and the catalytic reduction performance of CO2 at the cathode, achieving dynamic control. The optimal concentration is 0.01 mol / L Cs. + Concentration can achieve the highest selectivity and stability of the target product.
[0030] The main technical features and performance advantages of this invention are as follows:
[0031] (1) This study reveals for the first time the enhancement of CO2 electroreduction by cesium ion modification on the anode side, filling the gap in the existing technology of anode side modification and achieving a breakthrough from "single control of cathode" to "coordinated control of anode and cathode";
[0032] (2) The regulation method of the present invention can select different concentrations of cesium ion modification strategies according to the target product requirements (product selectivity, energy efficiency, stability), and has wide applicability;
[0033] (3) The present invention is compatible with the existing membrane electrode stack structure, does not require major modification of the stack, is easy to promote industrially, and enhances the industrial application potential of CO2 electroreduction technology. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the overall structure of the carbon dioxide electrocatalytic reduction system modified with cesium ions on the anode side according to the present invention. Detailed Implementation
[0035] The present invention will be further described in detail below through specific embodiments. These embodiments are intended to enable those skilled in the art to have a more comprehensive understanding of the present invention, but do not limit the present invention in any way.
[0036] The cathode catalyst used in this invention is uniformly a metal-based catalyst. In the examples, a commercial nano-silver (60-120 nm) catalyst was used, and the target product was CO.
[0037] In this embodiment, the membrane electrode stack uses a structure consisting of a cathode flow channel, a cathode gas diffusion electrode, an ion exchange membrane, a cesium ion modification layer, an anode catalyst, and an anode flow channel. The cathode is YLS-30 T carbon paper (1 mg / cm²) loaded with the Ag catalyst described above, and the anode is Ti felt loaded with IrO2. An anion exchange membrane is placed between the anode and cathode.
[0038] Example 1, Cs on the anode side + Stability test of the modification
[0039] Step 1: Prepare a 0.005 M Cs2CO3 aqueous solution and mix it with a certain proportion of binder FEPD 121 as an anode spraying solution, and spray it onto the prepared anode catalyst layer using a spray gun.
[0040] Example 2, Cs on the anode side + / K + Stability test of the modification
[0041] The only difference from Example 1 is that the cation is replaced by a mixture of 0.0025 M Cs2CO3 and 0.0025 M K2CO3 aqueous solution with a certain proportion of FEPD 121 as the anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0042] Example 3: Stability test of the anode side without cation modification
[0043] The only difference from Example 1 is that no cations are added. Instead, a certain proportion of FEPD 121 is mixed as the anode spraying liquid and sprayed onto the prepared anode catalyst layer using a spray gun.
[0044] Example 4: Stability test of the anode side without cation modification
[0045] The only difference from Example 1 is the absence of cation addition, with the original anode catalyst layer used as a comparison.
[0046] Electrocatalytic carbon dioxide reduction
[0047] The above-mentioned nano-silver powder catalyst was drop-coated onto the gas diffusion layer YLS-30T as the cathode working electrode (catalyst loading 1 mg / cm³). -2 In Examples 1-4, Ti felt loaded with IrO2 was used as the anode working electrode, and the anion exchange membrane was a Sustanion X37-50 RT. The anode test electrolyte was a KHCO3 solution, which was assembled into the membrane electrode. The CO2 flow rate was set at 40 sccm, the gas phase pressure at 1.1 bar, and the current density range was 100-2000 mA / cm. 2 Long-term stability testing was conducted.
[0048] A comparative example was also set up: the anode catalyst was not regulated by metal ions, and all other parameters were the same.
[0049] Current density is 100 mA / cm 2 The CO product was selectively reacted for 2 hours initially, and the results are shown in Table 1 below.
[0050] Table 1
[0051] .
[0052] The above embodiments demonstrate that the present invention, through cesium ion modification on the anolyte side, can significantly improve the performance of CO2 electroreduction to CO. To further optimize the optimal Cs... + Concentration; a control group with different concentrations is designed below for comparison.
[0053] Example 5, 0.0001 M Cs on the anode side + Stability test of the modification
[0054] The only difference from Example 1 is that the cesium ion concentration is changed to 0.0001 M Cs. + An aqueous solution is mixed with a certain proportion of FEPD 121 to form an anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0055] Example 6, 0.001 M Cs on the anode side + Stability test of the modification
[0056] The only difference from Example 1 is that the cesium ion concentration is changed to 0.001 M Cs. + An aqueous solution is mixed with a certain proportion of FEPD 121 to form an anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0057] Example 7, 0.01 M Cs on the anode side + Stability test of the modification
[0058] The only difference from Example 1 is that the cesium ion concentration is changed to 0.01 M Cs. + An aqueous solution is mixed with a certain proportion of FEPD121 to form an anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0059] Example 8, 0.1 M Cs on the anode side + Stability test of the modification
[0060] The only difference from Example 1 is that the cesium ion concentration is changed to 0.1 M Cs. + An aqueous solution is mixed with a certain proportion of FEPD121 to form an anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0061] Example 9, 1 M Cs on the anode side + Stability test of the modification
[0062] The only difference from Example 1 is that the cesium ion concentration is changed to 1 M Cs. + An aqueous solution is mixed with a certain proportion of FEPD121 to form an anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0063] Example 10, Anode-side saturation Cs + Stability test of the modification
[0064] The only difference from Example 1 is that the cesium ion concentration is changed to saturated Cs. + An aqueous solution is mixed with a certain proportion of FEPD121 to form an anode spraying solution, which is then sprayed onto the prepared anode catalyst layer using a spray gun.
[0065] Current density is 100 mA / cm 2 The selectivity of CO products is shown in Table 2 below.
[0066] Table 2
[0067] .
[0068] Test results show that in Examples 7 and 8, the CO Faraday efficiency remained above 90%, and the cell voltage remained essentially unchanged for over 100 hours. In the comparative example, after 100 hours, the CO Faraday efficiency dropped below 50%, and the cell voltage increased significantly. This was due to the appropriate amount of Cs on the anode side. + The modification inhibits the electromigration of cations in the electrolyte to the cathode, avoids the formation of salt deposits, prevents pore blockage or blockage of active sites of the catalyst, and enhances the electrocatalytic reduction of CO2 reaction.
[0069] The system and method of this invention fill the gap in anode-side control, are compatible with existing membrane electrode stacks, and have good prospects for industrial application.
Claims
1. A carbon dioxide electrocatalytic reduction system with cesium ion modification on the anode side, characterized in that, It includes the membrane electrode stack body, the anolyte supply subsystem, the gas phase control subsystem, the electrochemical testing subsystem, and the main control module; among which: The main body of the membrane electrode stack adopts a cathode flow channel-cathode gas diffusion electrode-ion exchange membrane-anode catalyst-anode flow channel arrangement structure; the cathode is a commercial metal catalyst, the anode is a Ti felt supported on IrO2, the anode catalyst side is modified with cesium ions, and an anion exchange membrane is placed between the cathode and the anode to ensure ion conduction; The anolyte supply subsystem is used to supply a specific type and concentration of anolyte to the anode side of the membrane electrode stack body. The anolyte exists in the form of a metal ion salt with a concentration range of 1×10⁻⁶. -4 mol / L to saturated solution; The gas phase control subsystem is connected to the cathode side of the membrane electrode stack to realize the flow rate and pressure regulation of CO2 feed gas; The electrochemical testing subsystem includes a programmable constant current source and a product detection module. The programmable constant current source is used for the main electrolysis testing of the membrane electrode stack, and the product detection module detects the composition and content of the electroreduction products, realizing real-time parameter control and data acquisition. The main control module enables real-time acquisition and feedback control of various parameters, ensuring the automated operation of the system.
2. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, In the membrane electrode stack, the cesium ion modification on the anode catalyst side is achieved by physical spraying to modify the cesium ion components on both sides of the anode catalyst.
3. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, In the main body of the membrane electrode stack, the anode catalyst side is modified with cesium ions. The cesium ion components are: perfluorosulfonic acid cationic ionomer, cesium ion solution and binder; the binder is PTFE emulsion or FEPD 121.
4. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, In the membrane electrode stack, the cesium ion modification on the anode catalyst side uses cesium salts selected from carbonates, bicarbonates, chlorides, bromides, iodides, sulfates, sulfites, phosphates, hydrogen phosphates, dihydrogen phosphates, nitrates, hydroxides, formates, acetates, oxalates, citrates, sulfonates, or their complex salts or mixed salts, or one or more of these.
5. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, In the main body of the membrane electrode stack, the anode catalyst side is modified with cesium ions, and the molar concentration of cesium ions is 0.001-0.1 mol / L.
6. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, The catalyst on the anode side has a parallel flow channel, and the electrolyte is delivered by a plunger pump at a flow rate of 10-100 mL / min. The temperature of the anode electrolyte is 25-100℃.
7. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, In the main body of the membrane electrode stack, the cathode electrocatalyst is a metal-based catalyst selected from gold, silver, copper, nickel, tin, bismuth, zinc, or selected from indium, gallium, palladium, cobalt, iron.
8. The carbon dioxide electrocatalytic reduction system according to claim 1, characterized in that, In the gas phase control subsystem, the CO2 feed gas flow rate is 0-200 sccm, and the cathode-side gas phase pressure is 1.0-2.5 bar.
9. The carbon dioxide electrocatalytic reduction operation based on the system according to any one of claims 1-8, characterized in that, The specific steps are as follows: Step 1, Prepare the anolyte: According to the target control requirements, dissolve the metal salt in deionized water, adjust the metal ion concentration to 0.001 mol / L to a saturated solution using the concentration adjustment component, and obtain the anolyte and store it in a storage tank; Step 2, System preheating and parameter initialization: Adjust the temperature of the anolyte to 25-100 ℃ using the temperature control component, introduce CO2 feed gas into the cathode side of the membrane electrode stack using the gas phase control subsystem, adjust the gas phase pressure to 1.0-2.5 bar, and set the initial current density of the programmable constant current source. Step 3, Anode-side electrolyte control: The plunger pump pumps the anolyte into the anode-side channel of the membrane electrode stack at a flow rate of 10-100 mL / min. The main control module, based on the real-time data from the electrochemical testing subsystem, regulates the cation concentration, electrolyte flow rate, and electrolyte temperature through the concentration adjustment component, plunger pump, and temperature control component, respectively, to achieve dynamic regulation of the cations on the anode side. Step 4, Electrocatalytic Reduction Reaction and Product Detection: The membrane electrode stack undergoes CO2 electrocatalytic reduction reaction under set parameters. The product detection module detects the cathode product in real time, and the main control module provides feedback on the cesium ion modification effect on the anode side based on the product detection results.
10. The application of the system as described in claims 1-9 in the electrocatalytic reduction of carbon dioxide to carbon monoxide.