An electrode device with synergistic effect of stirring, aeration and electrocatalysis

Abstract

This invention discloses an electrode device with synergistic effects of stirring, aeration, and electrocatalysis, belonging to the field of electrocatalysis technology. The device includes a hollow stepper motor, a hollow stirring shaft, a gas slip ring, an electric slip ring, and a porous cylindrical electrode. The hollow stepper motor drives the hollow stirring shaft to rotate. The gas slip ring is disposed at the upper end of the hollow stirring shaft and communicates with its cavity for introducing gas. The electric slip ring is disposed on the hollow stirring shaft for introducing current. The porous cylindrical electrode is fixedly connected to the lower end of the hollow stirring shaft and is coaxially arranged with the hollow stirring shaft. Its internal cavity communicates with the cavity of the hollow stirring shaft. Several channels communicating with the cavity are formed on the sidewall of the electrode. An electrocatalytic active layer is disposed on the outer surface of the electrode and in the shallow region of the channels. This invention has a compact structure, high mass transfer efficiency, and is suitable for electrocatalytic synthesis of hydrogen peroxide, reduction of carbon dioxide, and other gas-liquid-solid three-phase electrocatalytic systems.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, specifically relating to an electrode device with synergistic effects of stirring, aeration and electrocatalysis, suitable for gas-liquid-solid three-phase electrocatalytic reaction systems for the electrocatalytic synthesis of hydrogen peroxide (H2O2) and the reduction of carbon dioxide (CO2). Background Technology

[0002] Electrocatalytic synthesis technology is an important approach to achieving green chemical processes. Among these, the electrocatalytic oxygen reduction synthesis of fuels or chemicals such as H2O2, formic acid (HCOOH), and methane (CH4) is currently a research hotspot. These reactions typically involve gaseous reactants (such as O2 and CO2), liquid electrolytes, and solid electrode catalysts, belonging to a typical gas-liquid-solid three-phase reaction system.

[0003] In these three-phase reactions, the overall reaction rate depends not only on the intrinsic activity of the catalyst but also, and perhaps more importantly, on the mass transfer efficiency of the reactants at the gas-liquid-solid interface. Specifically, gaseous reactants need to dissolve in the electrolyte and diffuse to the active sites on the electrode surface; this mass transfer process often becomes the rate-determining step of the entire reaction. Traditional gas supply methods often employ bottom bubbling in the reactor, where the gas rises as bubbles and randomly contacts the electrode surface. This results in low gas utilization, long mass transfer paths, and a tendency to form large diffusion boundary layers, limiting further increases in the reaction rate.

[0004] To address these issues, various improvement schemes have emerged in the existing technology. For example, static gas diffusion electrodes attempt to optimize the three-phase interface by constructing a composite structure of a gas diffusion layer and a catalyst layer; however, mass transfer on the liquid side still mainly relies on natural diffusion, which is prone to water flooding or salting out, leading to performance degradation. Rotating disk electrodes, while able to thin the diffusion layer through high-speed rotation, lack the ability to continuously supply gas in situ and are difficult to scale up for application. Split-type systems, which independently set up the stirrer, aerator, and electrode, can achieve their respective functions, but the system is complex, occupies a large space, and lacks coordination between functional units, making it difficult to achieve active and integrated control of the mass transfer process.

[0005] Therefore, developing a novel electrode device that can integrate gas supply, liquid stirring, current conduction and catalytic reaction in situ and achieve synergistic enhancement of mass transfer process is of great significance for improving the efficiency of gas-liquid-solid three-phase electrocatalytic synthesis and promoting the industrial application of related technologies. Summary of the Invention

[0006] In view of the problems existing in the prior art of gas-liquid-solid three-phase electrocatalytic reactions, such as low mass transfer efficiency, low gas utilization rate, complex system structure and scattered functions, an electrode device with the synergistic effects of stirring, aeration and electrocatalysis is provided. By integrating the functions of stirring, aeration, conductivity and catalysis into a single rotating unit, this device realizes the synergistic effects of in-situ gas supply and forced convection stirring, fundamentally strengthening the mass transfer process at the gas-liquid-solid three-phase interface.

[0007] The present invention is realized through the following technical solutions: An electrode device with the synergistic effects of stirring, aeration and electrocatalysis, comprising: A hollow stepping motor with a hollow structure inside its rotor; A hollow stirring shaft rod is penetrated and arranged inside the rotor of the hollow stepping motor and coaxially fixedly connected to the rotor, so as to be driven to rotate by the hollow stepping motor. The hollow stirring shaft rod has a gas passage penetrating axially along it; An air slip ring is fixedly arranged at one end of the hollow stirring shaft rod. The air outlet of the air slip ring is communicated with the gas passage of the hollow stirring shaft rod, and the air inlet is used to connect an external gas source; An electric slip ring, the rotor of the electric slip ring is fixedly arranged on the hollow stirring shaft rod, and the stator of the electric slip ring is used to connect an external power source; A porous cylindrical electrode is detachably connected to the other end of the hollow stirring shaft rod and coaxially arranged with the hollow stirring shaft rod; the porous cylindrical electrode is a cylindrical structure with a cavity inside, and its cavity is communicated with the gas passage of the hollow stirring shaft rod; a plurality of air holes communicating with its cavity are arranged on the outer side wall of the porous cylindrical electrode; the porous cylindrical electrode is electrically connected to the electric slip ring, and an electrocatalytic active layer is arranged on the outer surface of the porous cylindrical electrode and the inner wall of the air hole passage.

[0008] Preferably, the rotor of the air slip ring is threadedly connected to one end of the hollow stirring shaft rod and rotates therewith. The stator of the air slip ring is connected to an external gas source through a quick-insert air pipe connector threadedly connected thereto, and the stator of the air slip ring remains relatively fixed with respect to the outer shell of the hollow stepping motor.

[0009] Preferably, a motor socket is arranged on the outer shell of the hollow stepping motor, and the motor socket is used to connect a motor driving power source.

[0010] Preferably, the hollow stirring shaft rod penetrates through the entire electrode device, driving the rotor of the air slip ring, the rotor of the electric slip ring and the porous cylindrical electrode to rotate.

[0011] Preferably, the electric slip ring stator is relatively fixed to the housing of the hollow stepper motor and is connected to an external power source through a wire, while the electric slip ring rotor is connected to a porous cylindrical electrode; the electric slip ring rotor is hollow inside and is coaxially connected to the hollow stirring shaft and rotates synchronously.

[0012] Preferably, the porous cylindrical electrode has a porous cylindrical structure and is made of conductive material. The porous cylindrical electrode is threadedly connected to the hollow stirring shaft to achieve aeration. The porous cylindrical electrode is loaded with an electrocatalytic active layer on its exterior, and the porous cylindrical electrode is connected to the electric slip ring rotor through a second wire to achieve energization.

[0013] Preferably, the electrocatalytic active layer comprises at least one of carbon nanotubes, modified carbon materials, metal or metal oxide catalysts.

[0014] An electrocatalytic method, employing the aforementioned electrode device with synergistic effects of stirring, aeration, and electrocatalysis, includes the following steps: A porous cylindrical electrode loaded with a corresponding electrocatalytic active layer is installed at the lower end of a hollow stirring shaft, and the porous cylindrical electrode is placed inside the reactor. The electrolyte is placed into the reaction vessel, so that the porous cylindrical electrode is immersed in the electrolyte; Start the hollow stepper motor to drive the hollow stirring shaft and porous cylindrical electrode to rotate and stir the electrolyte; The reaction gas is introduced into the gas channel of the hollow stirring shaft and the cavity of the porous cylindrical electrode through the air slip ring. The cavity includes several interconnected microchannels. The reaction gas diffuses to the electrode surface through the microchannels of the porous cylindrical electrode and forms a gas-liquid-solid three-phase reaction interface with the electrolyte. By passing an electric current through an electric slip ring to a porous cylindrical electrode, the reaction gas undergoes an electrochemical reaction on the surface of the porous cylindrical electrode under the electrocatalytic action of the electrocatalytic active layer. The synergistic effect of rotating and stirring with gas diffusion using a porous cylindrical electrode enhances mass transfer and renews the reaction interface, thereby improving the conversion efficiency and selectivity of the electrosynthesis reaction.

[0015] The beneficial effects of this invention are as follows: 1. This solution breaks away from the traditional functional separation architecture of gas-liquid-solid three-phase reaction systems. Through the synergistic innovation of "axial integration" and "in-situ mass transfer," it constructs a highly efficient integrated reaction. The four major functions of mechanical stirring, gas transport, current conduction, and catalytic reaction are physically integrated along the same rotation axis to form a compact functional unit. This allows gaseous reactants to be directly transported to the interior of the rotating porous cylindrical electrode, where they are in-situ precipitated from the catalytic reaction interface on the electrode surface. Combined with the forced turbulence generated by the electrode rotation, the gas and liquid reactants are "actively transported," overcoming the limitations of reactant mass transfer and improving reaction efficiency.

[0016] 2. Revolutionary improvement in mass transfer efficiency: Through the active synergistic mechanism of "rotational internal gas supply" and "forced convection stirring", gaseous reactants are directly transported to the catalytic interface and the diffusion boundary layer is broken up, which fundamentally solves the mass transfer bottleneck of three-phase reaction.

[0017] 3. Stable and reliable operation: The integrated transmission and sealing solution designed specifically for dynamic working conditions effectively solves the problems of continuous ventilation, stable conductivity and sealing of the reaction system under rotation, ensuring the stability and safety of the electrode device for long-term continuous operation under high current density.

[0018] 4. Platform-based technology is easily expandable: This electrode device is a universal "gas-liquid-solid" three-phase electrocatalytic reaction platform. By replacing the electrode catalyst layer, it can be easily applied to CO2 reduction. 、 Electrocatalytic reactions of different gases, such as O2 reduction, have strong technological scalability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this scheme or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 This is a schematic diagram of the electrode device in the electrocatalytic synthesis process of this scheme.

[0021] In the diagram: 1-Air slip ring stator; 2-Air slip ring; 3-Air slip ring rotor; 4-Hollow stirring shaft; 5-Hollow stepper motor; 6-Motor socket; 7-Wire 1; 8-Electric slip ring stator; 9-Electric slip ring rotor; 10-Electric slip ring; 11-Wire 2; 12-Porous cylindrical electrode; 13-Fixing rod. Detailed Implementation

[0022] The present invention will be further described below with reference to specific implementation examples. However, the scope of protection of the present invention is not limited to the following descriptions: Example 1 like Figure 1 As shown, this embodiment provides an electrode device with synergistic effects of stirring, aeration, and electrocatalysis, the specific structure of which is as follows: Hollow Stepper Motor 5: A stepper motor with a moderate body length and a 12mm hollow rotor aperture is selected. Its housing is equipped with a motor socket 6 for connecting an external motor driver. The hollow stepper motor 5 serves as the power source for the device, and its hollow structure also functions as part of the gas passage.

[0023] Hollow stirring shaft 4: Made of POM (polyoxymethylene) tubing with an outer diameter of 12mm and a wall thickness of 2mm, it has good insulation and corrosion resistance. The hollow stirring shaft 4 is inserted through the rotor of the hollow stepper motor 5 and is fixedly connected to the rotor via a keyway or set screws to ensure synchronous rotation. The hollow stirring shaft 4 has an axially continuous ventilation channel with a diameter of approximately 8mm.

[0024] Air slip ring 2: Fixedly installed on the upper end of the hollow stirring shaft 4. The air slip ring rotor 3 is connected to the upper end of the hollow stirring shaft 4 via threads and rotates together with the shaft; the air slip ring stator 1 is fixedly connected to the housing of the hollow stepper motor 5 via a fixing rod 13, keeping it stationary, and is connected to an external air source (such as O2 or CO2) via a quick-connect air pipe connector. The air outlet of the air slip ring 2 is rotatably and sealedly connected to the air passage of the hollow stirring shaft 4, ensuring that gas can continuously and stably enter the shaft during rotation. The air slip ring used in this embodiment has a working pressure ≤0.8MPa and a maximum speed of up to 2000rpm, meeting the dynamic sealing requirements.

[0025] The electric slip ring 10 is fixedly mounted on the hollow stirring shaft 4, located below the hollow stepper motor 5. The electric slip ring rotor 9 has a hollow structure, is sleeved and fixed on the hollow stirring shaft 4, and rotates coaxially with the shaft. The electric slip ring stator 8 is fixedly connected to the housing of the hollow stepper motor 5 via a fixing rod 13, keeping it stationary. The electric slip ring stator 8 is connected to an external DC power supply via wire 7, and the electric slip ring rotor 9 is electrically connected to the lower porous cylindrical electrode 12 via wire 11. The electric slip ring selected in this embodiment has a rated current of 5A, a rated voltage of 24V, and a contact resistance of less than 10mΩ, meeting the stable power supply requirements at a current density of 15 mA / cm² in subsequent experiments.

[0026] Porous cylindrical electrode 12: detachably connected to the lower end of the hollow stirring shaft 4. The electrode substrate is a porous titanium cylinder with an average pore size of approximately 1.2 mm, a diameter of 25 mm, and a length of 50 mm. One end of the electrode is machined with an internal thread, which engages with the external thread at the lower end of the hollow stirring shaft 4 to achieve mechanical fixation and gas path communication. Several micropores (aeration channels) are uniformly formed on the sidewall of the electrode, communicating with the internal cavity of the electrode. An electrocatalytic active layer is loaded on the outer surface of the electrode and the inner wall of the micropores. In this embodiment, the active layer is made of carbon nanotubes, loaded onto the electrode surface through an impregnation-drying process. The electrode is electrically connected to the electric slip ring rotor 9 via wire 11.

[0027] The electrocatalytic method using the above-mentioned electrode device includes the following steps: The porous cylindrical electrode 12 loaded with the corresponding electrocatalytic active layer is installed at the lower end of the hollow stirring shaft 4, and the porous cylindrical electrode 12 is placed into the reactor. The electrolyte is placed into the reaction vessel, so that the porous cylindrical electrode 12 is immersed in the electrolyte; Start the hollow stepper motor 5 to drive the hollow stirring shaft 4 and the porous cylindrical electrode 12 to rotate and stir the electrolyte; The gas is introduced into the gas channel of the hollow stirring shaft 4 and the cavity of the porous cylindrical electrode 12 through the air slip ring 2. The cavity includes several interconnected microchannels. The gas diffuses to the electrode surface through the microchannels of the porous cylindrical electrode 12 and forms a gas-liquid-solid three-phase reaction interface with the electrolyte. When an electric slip ring 10 is applied to the porous cylindrical electrode 12, the reaction gas undergoes an electrochemical reaction on the surface of the porous cylindrical electrode 12 under the electrocatalytic action of the electrocatalytic active layer. The rotational stirring of the porous cylindrical electrode 12 and the diffusion of gas work synergistically to enhance mass transfer and renew the reaction interface, thereby improving the conversion efficiency and selectivity of the electrosynthesis reaction.

[0028] Example 2 This embodiment presents a method for preparing H2O2 using an electrode device with synergistic effects of stirring, aeration, and electrocatalysis, comprising the following steps: A1: The porous cylindrical electrode 12 is impregnated with PTFE emulsion for hydrophobic treatment, and then carbon nanotube catalytic slurry containing Nafion binder is uniformly loaded on its surface and shallow pores by impregnation method. The slurry is dried at 80°C for 2 hours and heat-treated at 300°C for 1 hour to form a stable catalytic layer. A2: Insert the porous cylindrical electrode 12 into the electrolytic cell. The electrolyte is a Na2SO4 solution with a concentration of 0.5 mol / L and a pH of 6.8. A3: Set the speed of the hollow stepper motor 5 to 1200 rpm, the O2 introduction speed of the air slip ring 2 to 30 mL / min, and the current density output through the electric slip ring 10 to 15 mA / cm2.

[0029] Experiments showed that after 2 hours of treatment with this electrode device, the volume concentration of H2O2 in the electrolyte reached 3%, the Faraday efficiency was 95%, and the power consumption per unit of H2O2 synthesis was reduced by approximately 40% compared to a traditional static bubbling reactor. The performance degradation rate of the electrode device was less than 4% during 48 hours of continuous operation.

[0030] The specific steps for preparing H2O2 are as follows: 1. Electrode installation and airtightness check: Install the porous cylindrical electrode 12 loaded with the target catalyst layer to the lower end of the hollow stirring shaft 4, and insert the porous cylindrical electrode 12 into the reactor; add electrolyte solution to the reactor to the working liquid level; introduce reaction gas to pre-saturate the electrolyte solution, or directly start the electrode device to reach saturation during operation.

[0031] 2. Start-up power and setting mass transfer conditions: Set the target speed on the controller of the hollow stepper motor 5; for H2O2 synthesis, it is recommended to initially set it in the range of 300~1000 rpm and continuously optimize it; then, turn on the gas source, adjust the flow rate of the reaction gas to a suitable value, and the reaction gas enters the porous cylindrical electrode 12. Turn on the power to energize the hollow stirring shaft 4. The power supply adopts constant potential or constant current mode, and applies the required working potential or current density. 3. Cooperative operation: The electrode device achieves a cooperative operation state under the set rotation speed, gas flow rate and current / potential; that is, the gas is precipitated in situ on the surface of the porous cylindrical electrode 12 and dispersed by rotational shearing, while forced convection continuously renews the electrode-electrolyte contact interface.

[0032] Example 3 This embodiment designs a method for the electrocatalytic reduction of CO2 using an electrode device with synergistic effects of stirring, aeration, and electrocatalysis, comprising the following steps: B1: A copper-tin oxide composite catalytic layer was prepared by electrochemical deposition on the porous cylindrical electrode 12; B2: Install the porous cylindrical electrode 12 into the cathode chamber of an H-type electrolytic cell with an effective volume of 150 ml. The electrolyte is a KHCO3 solution with a concentration of 0.5 mol / L and a pH of 8.3. B3: Set the speed of the hollow stepper motor 5 to 700 rpm, the high-purity CO2 injection rate of the air slip ring 2 to 40 mL / min, and control the potential of the porous cylindrical electrode 12 to -1.1 V vs. RHE through the electric slip ring 10.

[0033] The operation steps of the electrode device in this embodiment are the same as in Embodiment 2, and parameters such as potential window and gas flow rate can be adjusted accordingly.

[0034] Experiments showed that after the reaction continued for 4 hours, gas chromatography and nuclear magnetic resonance analysis revealed that the space-time yield of HCOOH was 1.1 mol·L⁻¹·h⁻¹, with a Faraday efficiency of 96%. Compared with the traditional static CO₂ bubbling reaction system, the formate formation rate was increased by approximately 140%, and the performance degradation was less than 6% after 24 hours of continuous operation.

[0035] The above embodiments are merely illustrative examples and are not intended to limit the implementation; it is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of this technology.

Claims

1. An electrode device with synergistic effects of stirring, aeration, and electrocatalysis, characterized in that, include: Hollow stepper motor (5), whose rotor has a hollow structure; The hollow stirring shaft (4) is installed inside the rotor of the hollow stepper motor (5) and is fixedly connected to the rotor on the same axis so that it can be driven to rotate by the hollow stepper motor (5). The hollow stirring shaft (4) has a gas channel that runs through it along its axial direction. A slip ring (2) is fixedly installed at one end of the hollow stirring shaft (4). The air outlet of the slip ring (2) is connected to the gas channel of the hollow stirring shaft (4), and the air inlet is used to connect to an external gas source. An electric slip ring (10) has its electric slip ring rotor (9) fixedly mounted on the hollow stirring shaft (4) and its electric slip ring stator (8) used to connect to an external power source. A porous cylindrical electrode (12) is detachably connected to the other end of the hollow stirring shaft (4) and is coaxially arranged with the hollow stirring shaft (4); the porous cylindrical electrode (12) is a cylindrical structure with an internal cavity, and its cavity is connected to the gas channel of the hollow stirring shaft (4); multiple aeration channels communicating with its cavity are opened on the outer wall of the porous cylindrical electrode (12); the porous cylindrical electrode (12) is electrically connected to the electric slip ring (10), and an electrocatalytic active layer is provided on the outer surface of the porous cylindrical electrode (12) and the inner wall of the aeration channels.

2. The electrode device with synergistic effects of stirring, aeration, and electrocatalysis according to claim 1, characterized in that, The air slip ring rotor (3) of the air slip ring (2) is threadedly connected to one end of the hollow stirring shaft (4) and rotates accordingly. The air slip ring stator (1) of the air slip ring (2) is connected to an external air source through a quick-connect air pipe that is threadedly connected to it. The air slip ring stator (1) and the hollow stepper motor (5) housing remain relatively fixed.

3. The electrode device with synergistic effects of stirring, aeration, and electrocatalysis according to claim 1, characterized in that, The hollow stepper motor (5) has a motor socket (6) on its outer casing, which is used to connect the motor drive power supply.

4. The electrode device with synergistic effects of stirring, aeration, and electrocatalysis according to claim 1, characterized in that, The hollow stirring shaft (4) runs through the entire electrode device, driving the air slip ring rotor (3), the electric slip ring rotor (9), and the porous cylindrical electrode (12) of the air slip ring (2) to rotate.

5. The electrode device with synergistic effects of stirring, aeration, and electrocatalysis according to claim 1, characterized in that, The electric slip ring stator (8) is relatively fixed to the outer shell of the hollow stepper motor (5) and is connected to an external power source through a wire (7). At the same time, it is connected to a porous cylindrical electrode (12) through the electric slip ring rotor (9). The electric slip ring rotor (9) is hollow inside and is coaxially connected to the hollow stirring shaft (4) and rotates synchronously.

6. The electrode device with synergistic effects of stirring, aeration, and electrocatalysis according to claim 1, characterized in that, The porous cylindrical electrode (12) is a porous cylindrical structure made of conductive material. The porous cylindrical electrode (12) is threadedly connected to the hollow stirring shaft (4) to achieve air circulation. The porous cylindrical electrode (12) is loaded with an electrocatalytic active layer on its exterior. At the same time, the porous cylindrical electrode (12) is connected to the electric slip ring rotor (9) through the second wire (11) to achieve energization.

7. The electrode device with synergistic effects of stirring, aeration, and electrocatalysis according to claim 1, characterized in that, The electrocatalytic active layer includes at least one of carbon nanotubes, modified carbon materials, metal or metal oxide catalysts.

8. An electrocatalytic method, employing the electrode device as described in any one of claims 1 to 7, which has a synergistic effect of stirring, aeration, and electrocatalysis, characterized in that, Includes the following steps: The porous cylindrical electrode (12) loaded with the corresponding electrocatalytic active layer is installed at the lower end of the hollow stirring shaft (4), and the porous cylindrical electrode (12) is placed into the reactor; The electrolyte is placed into the reaction vessel, so that the porous cylindrical electrode (12) is immersed in the electrolyte; Start the hollow stepper motor (5) to drive the hollow stirring shaft (4) and the porous cylindrical electrode (12) to rotate and stir the electrolyte; The gas is introduced into the gas channel of the hollow stirring shaft (4) and the cavity of the porous cylindrical electrode (12) through the air slip ring (2). The cavity includes several interconnected microchannels. The gas diffuses to the electrode surface through the microchannels of the porous cylindrical electrode (12) and forms a gas-liquid-solid three-phase reaction interface with the electrolyte. Electricity is supplied to the porous cylindrical electrode (12) through the slip ring (10), and under the electrocatalytic action of the electrocatalytic active layer, the reaction gas undergoes an electrochemical reaction on the surface of the porous cylindrical electrode (12). The rotational stirring of the porous cylindrical electrode (12) and the diffusion of gas work synergistically to enhance mass transfer and renew the reaction interface, thereby improving the conversion efficiency and selectivity of the electrosynthesis reaction.

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