Plasma coupled electrocatalytic carbon dioxide conversion apparatus and method with product phase separation

Abstract

This invention discloses a plasma-coupled electrocatalytic carbon dioxide conversion device and method with product phase separation. Carbon dioxide gas forms non-thermodynamically equilibrium active carbon dioxide excited-state particles under the action of dielectric-barrier plasma discharge, effectively breaking high-energy carbon-oxygen bonds. These active particles are then converted into gaseous-liquid carbon products under the electrocatalytic action of a catalyst-loaded gas diffusion electrode. The gaseous products are directly discharged from the outlet, while the liquid products are briefly stored in a three-dimensional additively manufactured porous channel layer between the ion exchange membrane and catalyst layer for enrichment. The liquid products are then discharged and collected via a pulsed water circulation system. The high-concentration, low-impurity liquid products are easily utilized downstream. This invention features a flexible, convenient, modularly integrated, and environmentally friendly device, achieving efficient zero-carbon conversion of carbon dioxide throughout the entire process and a multiphase physical field design for multiphase carbon dioxide conversion.

Description

Technical Field

[0001] This invention relates to the fields of CO2 electrocatalysis and low-temperature plasma technology, and in particular to a plasma-coupled electrocatalytic carbon dioxide conversion device and method with separable gas-liquid products. Background Technology

[0002] With the rapid industrial development in recent years, carbon dioxide emissions have increased significantly. Electrocatalytic carbon dioxide conversion driven by renewable electricity can store excess electricity through high-value-added carbon dioxide products, promoting a closed natural carbon cycle. However, the industrial application of carbon dioxide electrocatalytic reduction technology is still limited by energy efficiency, selectivity, conversion rate, and catalytic activity. The inertness of carbon dioxide molecules makes it inhibited by the competitive hydrogen evolution reaction in aqueous solutions. Therefore, current research often employs gas diffusion electrodes to separate carbon dioxide gas from the electrolyte. The selective permeability of the gas diffusion electrode forms a reaction zone at the electrolyte-catalyst interface, thus improving the selectivity of carbon dioxide electrocatalysis.

[0003] Nevertheless, the electrocatalytic reduction of carbon dioxide at room temperature and pressure still targets gaseous carbon dioxide molecules. To break the inherent high activation energy barrier caused by high-energy carbon-oxygen bonds, current research has constructed a plasma-electrocatalytic coupling system. This system allows carbon dioxide molecules to generate active substances through plasma discharge before electrocatalytic conversion, followed by conversion of these carbon dioxide-like active substances at the electrocatalytic interface. This technique enhances the electrochemical activity of carbon dioxide molecule conversion at the electrode interface, facilitating the reaction. However, due to the quenching properties of plasma, excited-state particles are only generated in the region where plasma arc breakdown occurs. Therefore, traditional plasma-electrocatalytic coupling systems essentially involve plasma activating carbon dioxide to generate a stable molecular state of carbon monoxide / carbon dioxide / oxygen complex gas, which is then reduced to carbon by a catalyst at the electrocatalytic interface. Therefore, how to organically integrate the plasma interface with the electrocatalytic system to achieve a truly meaningful plasma-electrocatalytic coupling system and construct a non-thermodynamically equilibrium carbon-oxygen excited-state particle layer at the electrode interface is a problem that urgently needs to be solved.

[0004] Furthermore, the electrocatalytic reduction of carbon dioxide produces two phases: gas and liquid (gas phase: carbon monoxide, methane, etc.; liquid phase: methanol, ethanol, etc.). The separation and collection of these multi-phase products is a significant challenge for the industrialization of electrocatalytic carbon dioxide conversion. Gaseous products are typically discharged along with the introduced reaction gas at the gas outlet and purified downstream. However, due to the characteristics of the electrocatalytic system, liquid products can be transported from the cathode chamber across the anion exchange membrane to the anode chamber at high current densities and high product concentrations (crossover). This leads to the oxidation of liquid products to carbonates at the anode, significantly reducing the yield and selectivity of the carbon dioxide reduction system. Therefore, the continuous energy consumption of the liquid flow system, the large demand for electrolyte, and the contradiction between the need for electrolyte collection and separation remain major challenges restricting the high-current, industrial-scale electrocatalytic conversion of carbon dioxide. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of current technologies, such as the difficulty in separating liquid-phase products and the imperfections of plasma-electrocatalytic coupling processes, by proposing a plasma-coupled electrocatalytic carbon dioxide conversion device and method for product phase separation. This invention employs low-temperature dielectric barrier discharge plasma technology to achieve efficient carbon dioxide conversion and product separation.

[0006] The objective of this invention is achieved through the following technical solution: a plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation, the device comprising: a renewable energy modulation module and a plasma-coupled electrocatalytic module;

[0007] The renewable energy modulation module is used to connect to renewable energy sources for power supply, and through voltage and current conversion, it meets the power requirements of the plasma-coupled electrocatalytic module.

[0008] The plasma-coupled electrocatalysis module includes a dielectric barrier discharge array submodule, an electrocatalysis submodule, and a product separation submodule.

[0009] The dielectric barrier discharge array submodule is used for the dissociation and activation of carbon-oxygen bonds in carbon dioxide. Gaseous carbon dioxide is introduced into the plasma reactor array. By adjusting the physical characteristics of the plasma array, such as the input voltage and discharge frequency parameters, a gas breakdown discharge is generated to form a non-thermodynamic equilibrium plasma phase environment, thereby activating carbon dioxide and forming excited-state carbon dioxide particles in the plasma phase.

[0010] The electrocatalytic submodule is used to directly electrocatalytically convert excited-state carbon dioxide particles in the plasma phase on a gas diffusion electrode, and to directionally generate different products by adjusting the type of catalyst.

[0011] The product separation submodule is used to directionally separate gaseous and liquid products during collection. The gaseous products are discharged directly from the gas outlet, while the liquid products are temporarily stored in the porous channels constructed by additive manufacturing on the catalyst interface and periodically carried out by the pulse water circulation device. The porous channels are constructed on the catalyst interface of the gas diffusion electrode using a three-dimensional additive manufacturing method. After the electrocatalytic device is assembled, a micron-sized cavity will be formed at the gas diffusion electrode-ion exchange membrane interface to temporarily store the liquid products.

[0012] Furthermore, the renewable energy modulation module provides fluctuating energy input to power the plasma-coupled electrocatalytic module.

[0013] Furthermore, the dielectric barrier discharge array submodule is connected to a plasma power supply. By modulating the output voltage and frequency parameters of the power supply, the reactive gas is broken down to generate low-temperature plasmas with different physical properties.

[0014] Furthermore, the micron-sized pore flow channel is designed as a labyrinth to maximize mass transfer efficiency and product uniformity.

[0015] Furthermore, by collecting products through periodic pulsed water circulation, the concentrated liquid products that are briefly stored in the flow channel are collected through pulsed water circulation after enrichment, thereby improving product collection efficiency, preventing product inhibition of catalytic efficiency, and reducing energy consumption.

[0016] Furthermore, the liquid products collected from the circulating water are fractionated to obtain pure carbon products.

[0017] On the other hand, the present invention also provides a plasma-coupled electrocatalytic carbon dioxide conversion method with product phase separation, the method comprising the following steps:

[0018] (1) Renewable energy is converted by voltage and current to meet the power requirements of dielectric barrier discharge array and electrocatalysis;

[0019] (2) The carbon-oxygen bond in carbon dioxide is dissociated and activated by a dielectric barrier discharge array. Specifically, gaseous carbon dioxide is introduced into the plasma reactor array. By adjusting the physical characteristics of the plasma array, such as the input voltage and discharge frequency parameters, a gas breakdown discharge is generated to form a non-thermodynamic equilibrium plasma phase environment, thereby activating carbon dioxide and forming excited-state carbon dioxide particles in the plasma phase.

[0020] (3) Electrocatalytic conversion of excited-state carbon dioxide particles in plasma phase directly on a gas diffusion electrode, and different products are generated by adjusting the type of catalyst.

[0021] (4) The gas and liquid products are directionally separated during collection. The gas products are directly discharged from the gas outlet, and the liquid products are temporarily stored in the porous channels constructed by additive manufacturing on the catalyst interface and periodically carried out by the pulse water circulation device. The porous channels are constructed on the catalyst interface of the gas diffusion electrode by three-dimensional additive manufacturing. After the electrocatalytic device is assembled, a micron-sized cavity will be formed at the gas diffusion electrode-ion exchange membrane interface to temporarily store the liquid products.

[0022] The beneficial effects of this invention are:

[0023] (1) Mild reaction conditions. Utilizing the non-equilibrium state characteristics of low-temperature plasma, carbon-oxygen double bonds can be broken at room temperature and pressure, making efficient carbon dioxide conversion and utilization possible under mild conditions;

[0024] (2) High product selectivity. The directional conversion of plasma-phase carbon and oxygen active particles on the electrode reduces the reaction energy barrier, and the local concentration-recycle separation process of liquid products is beneficial to reducing energy consumption and coupling with subsequent processes;

[0025] (3) Upgraded coupling process. The four-step process of carbon dioxide molecules in the traditional plasma-electrocatalytic coupling system (steady state → excited state → steady state → electrocatalytic conversion) is transformed into a three-step process (steady state → excited state → electrocatalytic conversion), further improving the reaction rate;

[0026] (4) High environmental benefits. The entire device is powered entirely by renewable energy, and can achieve zero-carbon carbon dioxide conversion and utilization throughout the entire process. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the operation of a plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation. In the diagram, 1 is a solar photovoltaic panel; 2 is a voltage modulation module; 3 is a plasma-coupled electrocatalytic module; 4 is a pulsed water circulation system; and 5 is a liquid product collection tank.

[0028] Figure 2 This is a schematic diagram of a plasma-coupled electrocatalytic module, where 3-1 is a dielectric barrier discharge low-temperature plasma array; 3-2 is a gas diffusion catalytic layer; 3-3 is a micron-sized porous flow channel constructed by additive manufacturing; 3-4 is an ion exchange membrane; 3-5 is an anode catalytic layer; 3-6 is an anode electrolyte; 3-7 is a bipolar plate; 3-8 is a pulsed water circulation inlet; 3-9 is a pulsed water circulation outlet; 3-10 is an anode electrolyte inlet; 3-11 is an anode electrolyte outlet; 3-12 is a carbon dioxide inlet; and 3-13 is a carbon dioxide outlet.

[0029] Figure 3This is a magnified schematic diagram of a single unit of a dielectric barrier discharge low-temperature plasma array, where 3-1-1 is the electrode; 3-1-2 is the barrier dielectric; and 3-1-3 is the generated plasma.

[0030] Figure 4 It is a micron-sized porous channel constructed by additive manufacturing, wherein 3-3-1 is a gas diffusion layer; 3-3-2 is an interlayer liquid product; and 3-3-3 is an ion exchange membrane.

[0031] Figure 5 It is the cross-section of a micron-sized porous flow channel constructed by additive manufacturing. Detailed Implementation

[0032] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] This invention provides a plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation. Coupled with renewable energy power generation, it overcomes the shortcomings of existing processes, such as harsh reaction conditions, complex facilities, high carbon emissions, and severe environmental pollution. It enables the utilization of carbon dioxide at the downstream end of carbon capture in high-carbon emission plants, introducing renewable and clean electricity simultaneously with the conversion of carbon dioxide into high-value chemicals, achieving zero-carbon conversion throughout the entire process. This invention solves the problems of difficult product collection and separation and high energy consumption in downstream industrial applications of existing technologies. It allows for the direct recovery of high-concentration, high-value-added liquid carbon reduction products, which, after simple processing, can be directly fed into downstream chemical synthesis processes. It features simple reaction conditions, convenient process facilities and equipment, modular integration, and high environmental benefits.

[0034] The device provided by this invention includes: a renewable energy modulation module, a plasma-coupled electrocatalysis module 3, a pulsed water circulation system 4, and a liquid product collection tank 5;

[0035] The renewable energy modulation module includes a solar photovoltaic panel 1 and a voltage modulation module 2. The solar photovoltaic panel 1 (which can be replaced with other renewable energy sources) collects solar energy and transmits it to the voltage modulation module 2. The voltage modulation module 2 integrates voltage and current and outputs the energy to a plasma-coupled electrocatalytic module 3 and a pulsed water circulation device 4. The plasma-coupled electrocatalytic module 3 performs carbon dioxide conversion, synthesizing liquid / gase carbon products during operation. The liquid carbon products are transported to a liquid product storage tank 5 via the pulsed water circulation device 4 for storage and use. The pulsed water circulation device 4 collects products through periodic pulsed water circulation. The concentrated liquid products, briefly stored in the flow channel, are then collected again via pulsed water circulation, improving product collection efficiency, preventing product inhibition of catalytic efficiency, and reducing energy consumption. The liquid products collected by the circulating water are fractionated to obtain pure carbon products, which are then transported to the liquid product storage tank 5 for storage.

[0036] The plasma-coupled electrocatalytic module 3 consists of the following parts: ① a dielectric barrier discharge array submodule, which is composed of multiple sets of dielectric barrier discharge plasma miniature reactors. The miniature reactors have inlet and outlet pipes for the input of raw material gas and the output of product gas. The dielectric barrier discharge plasma array is connected to a high-frequency AC power supply. The high-voltage and high-frequency electricity output by the power supply can break down the gas in the reaction area to generate a dielectric barrier discharge plasma arc. ② an electrocatalytic module, which consists of a gas diffusion catalyst layer, an ion exchange membrane, an anode plate catalyst layer, and an anode plate. ③ a product separation submodule, in which the gas diffusion catalyst layer is constructed using a three-dimensional additive manufacturing method to create a labyrinthine micron-sized pore channel based on a traditional gas diffusion electrode, storing liquid products at the gas diffusion electrode-ion exchange membrane interface. The temporarily stored liquid products are periodically carried out by a pulsed water circulation device for downstream use.

[0037] like Figure 2 As shown, the plasma-coupled electrocatalytic module 3 includes a dielectric barrier discharge low-temperature plasma array 3-1, a gas diffusion catalyst layer 3-2, a micron-sized porous channel constructed by additive manufacturing 3-3, an ion exchange membrane 3-4, an anode catalyst layer 3-5, an anode electrolyte 3-6, a bipolar plate 3-7, a pulsed water circulation inlet 3-8, a pulsed water circulation outlet 3-9, an anode electrolyte inlet 3-10, an anode electrolyte outlet 3-11, a carbon dioxide inlet 3-12, and a carbon dioxide outlet 3-13; wherein, as... Figure 3 As shown, a single unit of the dielectric barrier low-temperature plasma array 3-1 includes an electrode 3-1-1, a barrier medium 3-1-2, and generated plasma 3-1-3. The barrier medium 3-1-2 is located between two electrodes 3-1-1, and the generated plasma 3-1-3 is located between the electrodes and the barrier medium. The plasma phase can react directly on the catalyst layer. This single unit is combined to form a dielectric barrier plasma array. The dielectric barrier low-temperature plasma array 3-1 is closely connected to the gas diffusion catalyst layer 3-2. Excited carbon dioxide active particles are formed on the gas diffusion catalyst layer 3-2. The gas diffusion catalyst layer 3-2 has micron-sized porous channels 3-3 constructed by additive manufacturing methods for temporarily storing liquid products, such as... Figure 4 and Figure 5As shown, the micron-sized porous channel 3-3 constructed by the additive manufacturing method includes a gas diffusion layer 3-3-1, an interlayer liquid product 3-3-2, and an ion exchange membrane 3-3-3. The gas diffusion layer 3-3-1 has flow channels designed in a labyrinth shape to enhance mass transfer kinetics, maximizing mass transfer efficiency and product uniformity. The interlayer liquid product 3-3-2 can be temporarily stored and carried out by a water circulation device. The micron-sized porous channel 3-3 constructed by the additive manufacturing method and the ion exchange membrane 3-3-3... 4. The ion exchange membrane 3-4 then contacts the anode catalyst layer 3-5. The anode catalyst layer 3-5 is connected to the anode electrolyte 3-6, and then connected to the bipolar plate 3-7. The pulse water circulation inlet 3-8 and the pulse water circulation outlet 3-9 are connected to the micron-sized pore channel 3-3. The bipolar plate 3-7 has an anode electrolyte inlet 3-10 and an anode electrolyte outlet 3-11. The dielectric barrier discharge low-temperature plasma array 3-1 has a carbon dioxide inlet 3-12 and a carbon dioxide outlet 3-13.

[0038] The renewable energy modulation module is used to input fluctuating energy from various renewable energy sources to power the plasma-coupled electrocatalytic module. Voltage conversion and transmission are achieved through the renewable energy modulation module, thus simultaneously meeting the power requirements (200W) of both the dielectric barrier discharge array submodule and the electrocatalytic submodule (100W) (240W). Operation is as follows: Figure 1 As shown: The voltage modulation module is supplied by photovoltaic panels or other renewable energy sources, and the voltage module outputs the electrical energy required by the electrocatalytic electrode, water circulation system, and plasma generator;

[0039] The dielectric barrier discharge array submodule is used for the dissociation and activation of carbon-oxygen bonds in carbon dioxide, constructing a dielectric barrier discharge plasma array between the gas diffusion layer and the gas inlet / outlet. The dielectric barrier discharge array submodule is connected to a plasma power supply, and by modulating the output voltage and frequency parameters of the power supply, it achieves the breakdown of the reactive gas to generate low-temperature plasmas with different physical properties. For example... Figure 2 As shown, after carbon dioxide is introduced into the dielectric barrier plasma, breakdown discharge occurs, forming a non-thermodynamically balanced plasma generation region. This region directly contacts the surface of the gas diffusion electrode. The electrode (catalyst) surface directly reduces and transforms the non-thermodynamically balanced plasma phase carbon dioxide excited-state particles. This upgrades the traditional two-stage coupling system process of plasma forming stable intermediate products and electrocatalysis reacting with intermediate products, making up for the shortcomings of the original plasma-electrocatalysis coupling system process, effectively reducing system energy consumption and improving conversion efficiency.

[0040] Adjust parameters such as the input voltage (9000kV) and discharge frequency (9500Hz) of the dielectric barrier discharge plasma array, such as... Figure 3As shown, a dielectric barrier discharge arc is generated, which promotes the construction of excited-state carbon dioxide particles and the dissociation rate and selectivity of carbon dioxide molecules.

[0041] The electrocatalytic submodule is used to directly electrocatalytically convert excited-state carbon dioxide particles in the plasma phase on a gas diffusion electrode, and to directionally generate different products by adjusting the type of catalyst.

[0042] The product separation submodule is used to directionally separate gaseous and liquid products during collection. Gaseous products are carried out by continuously introduced carbon dioxide gas and collected through a gas outlet for downstream conversion and utilization. The storage and collection of liquid products are achieved by constructing micron-sized porous channels at the catalyst interface of the gas diffusion layer using three-dimensional additive manufacturing. Figure 4 , 5 As shown, a pulsed water circulation system is used to periodically remove liquid carbon dioxide products (such as formic acid) from the porous flow channel. Specifically, when the device is in electrocatalytic operation, the cathode cavity is static, and a micron-sized cavity is formed between the gas diffusion electrode and the ion exchange membrane. When liquid carbon products are generated, this flow channel achieves local storage of the liquid products, and the products gradually concentrate and enrich as the electrocatalysis time continues. The pulsed water circulation system is turned on at intervals according to the current density and device size (generally 30min-60min), periodically removing the enriched liquid products from the reactor. This prevents the increase in product concentration from reducing the current density or increasing the power consumption, while achieving timely collection of products and long-term utilization of the catalyst. The removed liquid products can be converted into high-concentration liquid carbon products through simple fractionation and other methods for direct downstream use.

[0043] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation, characterized in that, The device includes: a renewable energy modulation module and a plasma-coupled electrocatalytic module; The renewable energy modulation module is used to connect to renewable energy sources for power supply, and through voltage and current conversion, it meets the power requirements of the plasma-coupled electrocatalytic module. The plasma-coupled electrocatalysis module includes a dielectric barrier discharge array submodule, an electrocatalysis submodule, and a product separation submodule. The dielectric barrier discharge array submodule is used for the dissociation and activation of carbon-oxygen bonds in carbon dioxide. Gaseous carbon dioxide is introduced into the plasma reactor array. By adjusting the physical characteristics of the plasma array, including the input voltage and discharge frequency parameters, a non-thermodynamic equilibrium plasma phase environment is generated by gas breakdown discharge, thereby activating carbon dioxide and forming excited-state carbon dioxide particles in the plasma phase. The electrocatalytic submodule is used to directly electrocatalytically convert excited-state carbon dioxide particles in the plasma phase on a gas diffusion electrode, and to directionally generate different products by adjusting the type of catalyst. The product separation submodule is used to directionally separate gaseous and liquid products during collection. The gaseous products are discharged directly from the gas outlet, while the liquid products are temporarily stored in the porous channels constructed by additive manufacturing on the catalyst interface and periodically carried out by the pulse water circulation device. The porous channels are constructed on the catalyst interface of the gas diffusion electrode using a three-dimensional additive manufacturing method. After the electrocatalytic device is assembled, a micron-sized cavity will be formed at the gas diffusion electrode-ion exchange membrane interface to temporarily store the liquid products.

2. The plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation according to claim 1, characterized in that, The renewable energy modulation module provides fluctuating energy input to power the plasma-coupled electrocatalytic module.

3. The plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation according to claim 1, characterized in that, The dielectric barrier discharge array submodule is connected to a plasma power supply. By modulating the output voltage and frequency parameters of the power supply, the reactive gas is broken down to generate low-temperature plasmas with different physical properties.

4. The plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation according to claim 1, characterized in that, The micron-sized pore flow channel is designed in a labyrinth shape to maximize mass transfer efficiency and product uniformity.

5. The plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation according to claim 4, characterized in that, By collecting products through periodic pulsed water circulation, the concentrated liquid products are briefly stored in the flow channel and then collected through pulsed water circulation after enrichment, which improves product collection efficiency, prevents product inhibition of catalytic efficiency, and reduces energy consumption.

6. The plasma-coupled electrocatalytic carbon dioxide conversion device with product phase separation according to claim 5, characterized in that, The liquid products collected from the circulating water are fractionated to obtain pure carbon products.

7. A plasma-coupled electrocatalytic carbon dioxide conversion method with product phase separation, characterized in that, The method includes the following steps: (1) Renewable energy is converted by voltage and current to meet the power requirements of dielectric barrier discharge array and electrocatalysis; (2) The carbon-oxygen bond in carbon dioxide is dissociated and activated by a dielectric barrier discharge array. Specifically, gaseous carbon dioxide is introduced into the plasma reactor array. By adjusting the physical characteristics of the plasma array, including the input voltage and discharge frequency parameters, a non-thermodynamic equilibrium plasma phase environment is generated by gas breakdown discharge, thereby activating carbon dioxide and forming excited state particles of carbon dioxide in the plasma phase. (3) Electrocatalytic conversion of excited-state carbon dioxide particles in plasma phase directly on a gas diffusion electrode, and different products are generated by adjusting the type of catalyst. (4) The gas and liquid products are directionally separated during collection. The gas products are directly discharged from the gas outlet, and the liquid products are temporarily stored in the porous channels constructed by additive manufacturing on the catalyst interface and periodically carried out by the pulse water circulation device. The porous channels are constructed on the catalyst interface of the gas diffusion electrode by three-dimensional additive manufacturing. After the electrocatalytic device is assembled, a micron-sized cavity will be formed at the gas diffusion electrode-ion exchange membrane interface to temporarily store the liquid products.

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