An apparatus and method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis.

Abstract

This invention discloses a device and method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis. The device includes a solar photovoltaic power generation module, a power modulation module, and a plasma-assisted electrocatalysis module. The solar photovoltaic power generation module and the power modulation module supply power to the entire device. The plasma-assisted electrocatalysis module achieves simultaneous carbon and nitrogen fixation through directional and selective catalysis of vibrationally excited carbon and nitrogen active groups. Using this device, carbon dioxide, water, and nitrogen can be used as reactants at ambient temperature and pressure to achieve co-activation conversion of carbon and nitrogen through plasma-assisted electrocatalysis. Under the control of the catalyst, single carbon / nitrogen products such as ammonia, carbon monoxide, and ethylene can be synthesized directionally and selectively. It can also organically couple and synthesize high-value-added small carbon and nitrogen molecules such as urea and amides. This invention features high energy efficiency, good environmental benefits, and adjustable product selectivity, which is beneficial for the efficient utilization of fluctuating electrical energy and the high-value-added conversion of small carbon and nitrogen energy molecules.

Description

Technical Field

[0001] This invention relates to the field of renewable energy-driven carbon fixation, nitrogen fixation, and electrosynthesis of high-value-added chemicals, and particularly to an apparatus and method for simultaneous carbon and nitrogen fixation based on plasma-assisted electrocatalysis. Background Technology

[0002] my country is the world's largest emitter of carbon dioxide (CO2), accounting for nearly 30% of global emissions. In recent years, my country has made CO2 reduction a major national strategy, introducing a series of carbon sequestration and reduction policies and measures. Furthermore, nitrogen (N2), as one of the most important elements in nature, plays a crucial role in human societal development. However, the extremely high bond energy (N≡N, 948 kJ / mol) and stable electronic structure of N2 make its dissociation and activation difficult, hindering its direct conversion and utilization. Therefore, renewable energy-driven carbon and nitrogen synergistic fixation, as well as green and efficient fuel synthesis or high-value utilization technologies based on carbon and nitrogen elements, are key to overcoming geographical and resource limitations and are central to building a sustainable energy system for the future.

[0003] Electrocatalysis, as a room-temperature and atmospheric-pressure energy small molecule conversion technology, can utilize surplus electricity generated from renewable energy sources for electro-chemical energy conversion, synthesizing high-value-added industrial chemicals from carbon and nitrogen small molecules. Some exploration has been conducted in the field of electrocatalytic carbon and nitrogen synthesis. Its advantage lies in its ability to utilize naturally abundant N2 as a nitrogen source and CO2 as a carbon source, achieving the synthesis of target products through flexible control of the reaction microenvironment. Compared to fossil fuel-driven multi-stage industrial pathways, electrocatalysis technology is more gentle and convenient. It can utilize modular equipment to adapt to local conditions, absorbing and utilizing spatiotemporally fluctuating electricity such as solar and wind power, achieving miniaturized and distributed carbon and nitrogen fixation conversion.

[0004] However, the development of simultaneous electrocatalytic carbon and nitrogen fixation remains constrained. N2 is poorly soluble in aqueous electrolyte systems, and the strong bond energies (948 kJ / mol for nitrogen triple bonds and 728 kJ / mol for carbon double bonds) make dissociation difficult. Furthermore, the competitive hydrogen evolution reaction (HER) also limits the selectivity of carbon-nitrogen conversion. Therefore, to improve reaction activity and achieve efficient dissociation of N2 and CO2 and targeted synthesis of target products, optimization of the entire electrochemical reaction system is urgently needed. Plasma technology has certain advantages in gas treatment and has been widely used in the disposal of atmospheric waste. It can break and recombine strong chemical bonds to form non-thermodynamically equilibrium active particles, but due to the random and non-directional nature of its reactions, it is less used in the synthesis of molecular chemicals. Therefore, the organic coupling of plasma technology, with its superior chemical bond dissociation capabilities, with electrocatalysis, which has directional synthesis characteristics, offers the potential to achieve simultaneous carbon and nitrogen fixation and highly selective targeted synthesis of specific products. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of current technologies by proposing a plasma-assisted electrocatalytic device and method for simultaneous carbon and nitrogen fixation. This method utilizes plasma-assisted electrocatalysis to achieve the co-activation and conversion of air (nitrogen) and carbon dioxide. By using dielectric barrier discharge plasma to form vibrationally excited carbon and nitrogen active particles, the reaction energy barrier for the dissociation of inert molecules is lowered. A rationally designed plasma-gas-liquid-solid four-phase reaction interface is constructed at the cathode catalytic interface of the membrane electrode electrolyzer. Through modulation of the catalytic microenvironment, the targeted and efficient synthesis of various carbon and nitrogen products is achieved. Solar photovoltaic power generation technology is coupled as the energy source for the reaction device. This improves upon the shortcomings of existing processes, such as harsh reaction conditions, complex facilities, high carbon emissions, and severe environmental pollution, achieving zero-carbon conversion throughout the entire process.

[0006] The objective of this invention is achieved through the following technical solution: A method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis, the device comprising: a solar photovoltaic power generation module, a power modulation module, and a plasma-assisted electrocatalysis module.

[0007] The solar photovoltaic power generation module is connected to the power modulation module, which converts the fluctuating DC power into AC power with a set voltage and frequency to power the plasma-assisted electrocatalysis module.

[0008] The plasma-assisted electrocatalytic module is used to activate air or inert nitrogen and carbon dioxide molecules to a vibrationally excited state that is not in thermodynamic equilibrium using plasma. The active carbon and nitrogen groups in the vibrationally excited state are directionally converted at the electrocatalytic interface. With plasma assistance, a plasma-gas-liquid-solid four-phase interface is formed at the cathode by adjusting the electrolyte, ion exchange membrane, and flow channel parameters. By adjusting the cathode potential and catalyst type, the selective catalytic conversion of nitrogen and carbon dioxide to ammonia, ethylene, ethanol, and carbon monoxide can be achieved, or organic coupling can be performed to form urea and amide.

[0009] Furthermore, the solar photovoltaic power generation module consists of solar photovoltaic panels and energy storage batteries. The solar photovoltaic panels capture renewable energy to provide energy for the device, and the energy storage batteries temporarily store surplus electrical energy.

[0010] Furthermore, the power modulation module consists of a photovoltaic inverter and its additional components, which converts the variable DC voltage generated by the solar photovoltaic power generation module into AC power with the frequency and voltage required for stable operation of the device.

[0011] Furthermore, the plasma-assisted electrocatalysis module consists of a dielectric barrier discharge plasma generator and a membrane electrode electrolyzer. The dielectric barrier discharge plasma is used for the dissociation and activation of nitrogen-nitrogen triple bonds and carbon-oxygen double bonds. By vibrating and exciting the target molecules, it forms non-thermodynamically equilibrium plasma-phase active particles, overcoming the Gibbs free energy barrier required for the chemical reaction. The membrane electrode electrolyzer is used for electrocatalytic directional conversion. Under the assistance of plasma, a plasma-gas-liquid-solid four-phase interface is formed at the cathode. Under the action of the catalyst, the selective synthesis of ammonia, carbon monoxide, ethylene, urea, and amide products from the plasma-phase active particles is achieved.

[0012] On the other hand, the present invention also provides a method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis, the method comprising the following steps:

[0013] (1) The energy collected by the solar photovoltaic power generation module is input into the power modulation module for regulation and conversion, and the fluctuating DC power is modulated into AC power that meets the steady-state operation of the plasma-assisted electrocatalysis module, thus forming a steady-state operating condition;

[0014] (2) Introduce air (or nitrogen) and carbon dioxide into the dielectric barrier discharge plasma generator of the plasma-assisted electrocatalysis module, adjust the physical characteristics and discharge parameters of the dielectric barrier discharge plasma generator to form gas breakdown, thereby constructing a non-thermodynamic equilibrium plasma phase environment, realizing the co-activation of nitrogen and carbon dioxide molecules, and forming vibrationally excited carbon and nitrogen particles.

[0015] (3) Vibrationally excited carbon and nitrogen particles are introduced into the cathode of the membrane electrode electrolysis cell of the plasma-assisted electrocatalysis module. By adjusting the parameters of the electrolyte, ion exchange membrane, and flow channel, a stable plasma-gas-liquid-solid four-phase reaction interface is formed. By controlling the cathode potential and the type of catalyst, the directional synthesis of vibrationally excited carbon and nitrogen particles into ammonia, carbon monoxide, ethylene, urea, and amide products is achieved.

[0016] Furthermore, the physical characteristics of the dielectric barrier discharge plasma generator in the plasma-assisted electrocatalysis module are adjusted by input voltage and carrier gas. The input voltage adjustment range is 5000kV to 8000kV, and the carrier gas adjustment is air or nitrogen:carbon dioxide ratio of 5:1 to 1:5. The discharge parameter adjustment is frequency adjustment, with a frequency adjustment range of 7500Hz to 9000Hz. The dielectric barrier discharge plasma generator can be a single unit or 2-10 reactors connected in parallel to form an array.

[0017] Furthermore, the electrolyte in the membrane electrode electrolyzer of the plasma-assisted electrocatalysis module is one of the following: a potassium hydroxide solution with a concentration of 0.1 mol / L to 1 mol / L, a potassium bicarbonate solution with a concentration of 0.1 mol / L to 1 mol / L, or a sodium sulfate solution with a concentration of 0.05 mol / L to 0.5 mol / L; the ion exchange membrane is one of the following: an anion exchange membrane or a bipolar membrane; the flow channel is one of the following: a parallel flow channel, a serpentine flow channel, or a finger-shaped flow channel; and the cathode catalyst is one of the following: a copper-nickel alloy, silver nanoparticles, copper-cobalt nanoparticles, indium oxide nanorods, or copper-cuprous oxide nanoclusters.

[0018] The beneficial effects of this invention are:

[0019] (1) High energy efficiency. By using plasma to gently excite inert particles to a vibrational excited state that is not in thermodynamic equilibrium, the energy barrier of traditional electrocatalysis when activating nitrogen-nitrogen triple bonds and carbon-oxygen double bonds is avoided;

[0020] (2) Good environmental benefits. Simultaneous nitrogen and carbon fixation is achieved using renewable energy under normal temperature and pressure conditions, avoiding the reaction conditions of high temperature and high pressure, and realizing the synthesis of high value-added carbon and nitrogen products on the basis of zero carbon throughout the process;

[0021] (3) Product selectivity is adjustable. By orderly controlling the catalytic interface, the device can synthesize products such as ammonia, carbon monoxide, ethylene, urea, and amide according to downstream needs, and can be widely matched to various application scenarios. Attached Figure Description

[0022] Figure 1The diagram shows the structure of the device, where 1 is the solar photovoltaic power generation module, 2 is the power transmission line, 3 is the power modulation module, 4 is the plasma power supply, 5 is the dielectric barrier discharge plasma reactor, 6 is the membrane electrode electrolyzer, 7 is the air cylinder, 8 is the carbon dioxide cylinder, and 9 is the gas transmission line.

[0023] Figure 2 This is a schematic diagram of a plasma-assisted electrocatalysis module, where 10 is a fixing nut, 11 is a gas inlet, 12 is a gas outlet, 13 is a cathode flow channel bipolar plate, 14 is a cathode catalyst layer, 15 is an ion exchange membrane, 16 is an anode catalyst layer, 17 is an anode flow channel bipolar plate, 18 is a fixing bolt, 19 is a gas pipeline, 20 is a gas inlet of the dielectric barrier discharge plasma reactor, 21 is a gas outlet of the dielectric barrier discharge plasma reactor, 22 is a high-voltage line, 23 is a low-voltage line, 24 is a high-voltage electrode, and 25 is a low-voltage electrode. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] This invention provides a plasma-assisted electrocatalytic simultaneous carbon and nitrogen fixation device and method, which avoids the high-temperature and high-pressure reaction conditions of traditional carbon dioxide and nitrogen fixation processes, solving the problems of complex facilities and high costs. It can be applied to practical scenarios such as chemical energy storage, distributed farmland fertilizer supply, and fine chemical synthesis. By capturing renewable energy from solar energy and driving the device, efficient and targeted simultaneous carbon and nitrogen fixation can be achieved with zero carbon dioxide emissions throughout the entire process. Introducing air and carbon dioxide into the device, through plasma discharge breakdown, forms non-thermodynamically equilibrium active carbon and nitrogen groups, lowering the dissociation energy barrier of inert molecules and facilitating the targeted conversion to various carbon and nitrogen products at the electrocatalytic interface. This method offers advantages such as high energy efficiency, good environmental benefits, and adjustable product selectivity.

[0026] The device provided by this invention includes: a solar photovoltaic power generation module, a power modulation module, and a plasma-assisted electrocatalysis module. The device operates as follows: Figure 1As shown, during operation, the solar photovoltaic power generation module 1 captures energy from solar energy and converts it into electrical energy. Fluctuating DC power is connected to the power modulation module 3 via the transmission line 2. The power modulation module 3 converts the DC power into AC power with a specific voltage / frequency required for the operation of downstream electrical equipment. When the device is started, the plasma power supply 4 is activated, and air and carbon dioxide are transported from the air cylinder 7 and carbon dioxide cylinder 8 to the dielectric barrier discharge plasma reactor 5 via the gas transmission line 9. The dielectric barrier discharge plasma reactor 5 performs breakdown discharge on the gas to form vibrationally excited carbon and nitrogen particles, which are then transported to the membrane electrode electrolyzer 6. A plasma-gas-liquid-solid four-phase interface is formed at the cathode catalytic interface of the membrane electrode electrolyzer 6. By regulating the catalytic microenvironment, efficient and directional selective synthesis of products such as ammonia, carbon monoxide, ethylene, urea, and amides is achieved.

[0027] The plasma-assisted electrocatalysis module is specifically configured as follows: Figure 2 As shown, the plasma power supply 4 can boost 220V AC power to the point of gas breakdown. High-voltage line 22 and low-voltage line 23, along with the high-voltage electrode 24 and low-voltage electrode 25 of the dielectric barrier discharge plasma reactor, allow the reaction gas to enter the gas inlet 20 of the dielectric barrier discharge plasma reactor. After forming vibrationally excited active particles, the gas is discharged from the gas outlet 21 of the dielectric barrier discharge plasma reactor and transported to the gas inlet 11 of the membrane electrode electrolyzer via gas pipeline 19. After a directional catalytic reaction, the gas is discharged from the gas outlet 12 and collected. The membrane electrode electrolyzer 6 consists of a fixing nut 10, a cathode flow channel bipolar plate 13, a cathode catalyst layer 14, an ion exchange membrane 15, an anode catalyst layer 16, an anode flow channel bipolar plate 17, and fixing bolts 18. The fixing nut 10 and fixing bolts 18 are used for fixing and assembly. The cathode flow channel bipolar plate 13 and the anode flow channel bipolar plate 17 are used for conductive current collection and flow field optimization. The cathode catalyst layer 14 and the anode catalyst layer 16 are used for catalytic reaction. The ion exchange membrane 15 is used for conductive conduction and selective ion transfer.

[0028] Example 1

[0029] This example demonstrates the selective synthesis of ammonia products.

[0030] Step I (Power Acquisition): Power is collected using a solar photovoltaic power generation module and transmitted to a power modulation module to convert the power into 220V AC power. Plasma power supplies, membrane electrode electrolyzers, etc. can be connected to the power supply.

[0031] Step II (Preparation of Membrane Electrode Catalyst): Prepare a 1 mol / L potassium hydroxide solution as both the cathode and anolyte. Use a bipolar membrane to separate the anode and cathode of the electrolytic cell. Sputter a 200 nm thick layer of copper nanoparticles onto carbon paper using magnetron sputtering. Then, electrodeposit the catalyst onto a 1 × 1 cm⁻¹ layer. -2Copper-nickel alloys were prepared by electrodeposition of nickel on a nano-copper layer. The electrodeposition was carried out in 100 mL of 0.05 mol / L dilute sulfuric acid + 0.01 mol / L nickel nitrate solution, with an electrodeposition current density of 100 mA cm⁻¹. -2 After assembly, they form a membrane electrode electrolyzer oriented towards ammonia synthesis;

[0032] Step III (Plasma Excitation): Air and carbon dioxide are introduced into the dielectric barrier discharge plasma array, the high-voltage line and the low-voltage line are connected, the high-voltage power supply is turned on, and the plasma power is adjusted to 50W. The discharged active carbon and nitrogen particles are introduced into the cathode through the gas inlet of the electrolytic cell via the pipeline.

[0033] Step IV (Directional Synthesis in Electrolytic Cell): Adjust the voltage of the electrolytic cell to make the cathode potential controllable to -0.2V vs. RHE, start electrolysis in constant voltage mode, collect the product at the outlet, and obtain a large amount of ammonia product.

[0034] Example 2

[0035] This embodiment demonstrates the selective synthesis of carbon monoxide products.

[0036] Step I (Power Acquisition): Power is collected using a solar photovoltaic power generation module and transmitted to a power modulation module to convert the power into 220V AC power. Plasma power supplies, membrane electrode electrolyzers, etc. can be connected to the power supply.

[0037] Step II (Preparation of membrane electrode catalyst): Prepare a 0.1 mol / L potassium bicarbonate solution as the cathode electrolyte and anolyte. Use an anion exchange membrane to separate the cathode and anode of the electrolytic cell. Sputter a 500 nm thick layer of silver nanoparticles onto carbon paper using magnetron sputtering. After assembly, a membrane electrode electrolytic cell facing the carbon monoxide synthesis is formed.

[0038] Step III (Plasma Excitation): Air and carbon dioxide are introduced into the dielectric barrier discharge plasma array, the high-voltage line and the low-voltage line are connected, the high-voltage power supply is turned on, and the plasma power is adjusted to 100W. The discharged active carbon and nitrogen particles are introduced into the cathode through the gas inlet of the electrolytic cell via the pipeline.

[0039] Step IV (Directional Synthesis in Electrolytic Cell): Adjust the voltage of the electrolytic cell to make the cathode potential controllable to -1.5V vs. RHE, start electrolysis in constant voltage mode, collect the product at the outlet, and obtain a large amount of carbon monoxide product.

[0040] Example 3

[0041] This example demonstrates the selective synthesis of ethylene products.

[0042] Step I (Power Acquisition): Power is collected using a solar photovoltaic power generation module and transmitted to a power modulation module to convert the power into 220V AC power. Plasma power supplies, membrane electrode electrolyzers, etc. can be connected to the power supply.

[0043] Step II (Preparation of membrane electrode catalyst): Prepare a 0.1 mol / L potassium bicarbonate solution as the cathode electrolyte and anolyte. Use an anion exchange membrane to separate the cathode and anode of the electrolytic cell. Sputter 200 nm thick copper-cuprous oxide nanoclusters on carbon paper using a dual-target magnetron sputtering method. After assembly, a membrane electrode electrolytic cell facing the ethylene synthesis is formed.

[0044] Step III (Plasma Excitation): Air and carbon dioxide are introduced into the dielectric barrier discharge plasma array, the high-voltage line and the low-voltage line are connected, the high-voltage power supply is turned on, and the plasma power is adjusted to 100W. The discharged active carbon and nitrogen particles are introduced into the cathode through the gas inlet of the electrolytic cell via the pipeline.

[0045] Step IV (Directional Synthesis in Electrolytic Cell): Adjust the voltage of the electrolytic cell to make the cathode potential controllable to -1.2V vs. RHE, start electrolysis in constant voltage mode, collect the product at the outlet, and obtain a large amount of ethylene product.

[0046] Example 4

[0047] This embodiment describes the selective synthesis of urea products.

[0048] Step I (Power Acquisition): Power is collected using a solar photovoltaic power generation module and transmitted to a power modulation module to convert the power into 220V AC power. Plasma power supplies, membrane electrode electrolyzers, etc. can be connected to the power supply.

[0049] Step II (Preparation of Membrane Electrode Catalyst): Prepare a 1 mol / L potassium hydroxide solution as the cathode electrolyte and anolyte. Use a bipolar membrane to separate the anode and cathode of the electrolytic cell. Prepare indium oxide nanorods on carbon paper using a hydrothermal method. Dissolve 1 gram of indium chloride in 50 mL of deionized water. Adjust the pH of the solution to 9.5 by adding NH4OH. Transfer the solution to a 100 mL hydrothermal reactor and keep it in an oven at 180 °C for 10 hours. Allow it to cool naturally to room temperature. Wash the precipitate, dry it, and calcine it in air at 500 °C for 2 hours to obtain indium oxide nanorods. Assemble them to form a membrane electrode electrolytic cell for urea synthesis.

[0050] Step III (Plasma Excitation): Air and carbon dioxide are introduced into the dielectric barrier discharge plasma array, the high-voltage line and the low-voltage line are connected, the high-voltage power supply is turned on, and the plasma power is adjusted to 50W. The discharged active carbon and nitrogen particles are introduced into the cathode through the gas inlet of the electrolytic cell via the pipeline.

[0051] Step IV (Directional Synthesis in Electrolytic Cell): Adjust the voltage of the electrolytic cell to make the cathode potential controllable to -1.2V vs. RHE, start electrolysis in constant voltage mode, collect the product at the outlet, and obtain a large amount of urea product.

[0052] 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 method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis, characterized in that, The method includes the following steps: (1) The energy collected by the solar photovoltaic power generation module is input into the power modulation module for regulation and conversion, and the fluctuating DC power supply is modulated into AC power that meets the steady-state operation of the plasma-assisted electrocatalysis module, thus forming a steady-state operating condition; (2) Introduce air or nitrogen and carbon dioxide into the dielectric barrier discharge plasma generator of the plasma-assisted electrocatalysis module, adjust the physical characteristics and discharge parameters of the dielectric barrier discharge plasma generator to form gas breakdown, thereby constructing a non-thermodynamic equilibrium plasma phase environment, realizing the co-activation of nitrogen and carbon dioxide molecules, and forming vibrationally excited carbon and nitrogen particles. (3) Vibrationally excited carbon and nitrogen particles are introduced into the cathode of the membrane electrode electrolysis cell of the plasma-assisted electrocatalysis module. A stable plasma-gas-liquid-solid four-phase reaction interface is formed by adjusting the electrolyte, ion exchange membrane and flow channel parameters. The directional synthesis of vibrationally excited carbon and nitrogen particles into various carbon and nitrogen products is achieved by controlling the cathode potential and catalyst type.

2. The method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis according to claim 1, characterized in that, The physical characteristics of the dielectric barrier discharge plasma generator in the plasma-assisted electrocatalysis module are adjusted by adjusting the input voltage and the carrier gas. The input voltage adjustment range is 5000 kV~8000 kV, and the carrier gas adjustment is air or nitrogen:carbon dioxide ratio of 5:1~1:

5. The discharge parameter adjustment is frequency adjustment, with a frequency adjustment range of 7500 Hz~9000 Hz. The dielectric barrier discharge plasma generator can be a single generator or 2-10 generators connected in parallel to form an array.

3. The method for simultaneous carbon and nitrogen fixation via plasma-assisted electrocatalysis according to claim 1, characterized in that, The electrolyte in the membrane electrode electrolyzer of the plasma-assisted electrocatalysis module is one of the following: a potassium hydroxide solution with a concentration of 0.1 mol / L to 1 mol / L, a potassium bicarbonate solution with a concentration of 0.1 mol / L to 1 mol / L, or a sodium sulfate solution with a concentration of 0.05 mol / L to 0.5 mol / L; the ion exchange membrane is one of the following: an anion exchange membrane or a bipolar membrane; the flow channel is one of the following: a parallel flow channel, a serpentine flow channel, or a finger-shaped flow channel; and the cathode catalyst is one of the following: a copper-nickel alloy, silver nanoparticles, copper-cobalt nanoparticles, indium oxide nanorods, or copper-cuprous oxide nanoclusters.

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