Reactor, system and method for converting carbon dioxide and water by plasma

Abstract

The invention discloses a reactor, system and method for converting plasma into carbon dioxide and water, and belongs to the technical field of greenhouse gas resource utilization and plasma application. By arranging the double-dielectric-tube structure, arranging the high-voltage needle-shaped electrode in the inner dielectric tube and arranging the low-voltage annular electrode at the bottom of the inner dielectric tube, atmospheric pressure glow discharge can be generated between the electrodes, and plasma jet is achieved; meanwhile, a biomass carbon placement area and a catalyst placement area are arranged in the plasma jet area, and multi-stage catalysis is realized through the synergistic effect between plasma and a catalyst, so that the selectivity of a target product is improved. According to the invention, the plasma is driven by renewable zero-carbon electric power, CO2 and H2O are catalyzed to be converted into synthesis gas and acetic acid, and the conversion rate, the energy efficiency and the liquid product selectivity in CO2 and H2O conversion are improved.

Description

Technical Field

[0001] The present invention relates to the field of greenhouse gas resource utilization and plasma application technology, and in particular to a reactor, system and method for converting carbon dioxide and water through plasma. Background Art

[0002] CO 2 Effective capture and efficient utilization is not only a deep development of the abundant and economic carbon resources in nature, but also a solution to CO 2 It is a key way to reduce excess emissions, promote resource recycling and promote green economic transformation.

[0003] Plasma, as the fourth state of matter, has unique properties in CO 2 The field of plasma conversion shows great potential. It is composed of multiple particles such as electrons, positive ions, negative ions, excited and ground state atoms or molecules, photons, etc., showing a highly ionized and charge-balanced gas state. According to the state of plasma, it can be divided into: (1) equilibrium plasma, a plasma with high gas pressure and electron temperature roughly equal to gas temperature; (2) non-equilibrium plasma, a plasma with electron temperature much greater than gas temperature under low gas pressure or normal pressure. Non-equilibrium plasma, as an important form of plasma, has the characteristics of catalyzing CO 2 Ideal for transformation reactions.

[0004] Currently, the use of nonequilibrium plasma catalysis for CO 2 Conversion is to achieve stable performance CO under normal temperature and pressure conditions 2 One of the key technologies for the activation reaction of molecules. On the one hand, non-equilibrium plasma can activate and decompose CO under relatively mild temperature and pressure conditions. 2 Ground state molecules produce high-density active substances with a theoretical energy utilization efficiency of up to 90%; on the other hand, non-equilibrium plasma can be driven by renewable zero-carbon electricity such as photovoltaics and wind power, thereby realizing the on-site consumption of new energy and forming a green, low-carbon and sustainable development industrial system. 2 Adding hydrogen source during the conversion process can synthesize high value-added products and effectively promote carbon cycle, while water (H 2 O) is the most readily available hydrogen source, and plasma catalyzes CO 2 and H 2 O conversion to synthesize high value-added products meets the requirements of sustainable development and has high industrial application value.

[0005] However, nonequilibrium plasma catalysis for CO2 and water conversion includes the following difficulties: 2 The strong adsorption effect of O on electrons inhibits the CO 2 Transformation, introduction of H 2O followed by CO 2 The conversion rate was significantly reduced; CO 2 and H 2 The main product of O conversion is synthesis gas. The separation, storage and transportation costs of gas products are high, while the product selectivity of liquid products such as alcohols and acids is extremely low.

[0006] Therefore, how to design a reactor, system and related methods for non-equilibrium plasma catalytic conversion of carbon dioxide and water to solve the above difficulties and achieve CO 2 and H 2 High conversion rate and liquid product selectivity in O conversion have become technical challenges that technicians in this field need to overcome urgently. Summary of the invention

[0007] The object of the present invention is to provide a reactor, system and method for plasma conversion of carbon dioxide and water to solve the problems existing in the prior art.

[0008] The present invention solves the above technical problems through the following technical solutions: A reactor for converting carbon dioxide and water into plasma, comprising an outer medium tube, an inner medium tube, a high-pressure needle electrode, a low-pressure ring electrode and a mesh support; the top and bottom of the outer medium tube are respectively provided with an inlet and an outlet, and the mesh support is fixedly arranged on the horizontal section of the lower part of the outer medium tube; The inner medium tube is shorter than the outer medium tube and is coaxially sleeved in the outer medium tube. The high-voltage needle electrode is shorter than the inner medium tube and is coaxially sleeved in the inner medium tube. The top ends of the inner medium tube and the high-voltage needle electrode are fixedly arranged on the top of the outer medium tube. The low-voltage ring electrode is arranged at the bottom of the inner medium tube. An annular gap is formed between the high-voltage needle electrode and the inner medium tube, and the annular gap is connected to the inlet for introducing reaction gases, which include carbon dioxide and water. A plasma discharge zone is formed between the bottom of the high-voltage needle electrode and the top of the low-voltage ring electrode for primary reaction. A plasma jet zone is formed between the bottom of the inner medium tube and the mesh support portion, and the plasma jet zone is provided with a biomass carbon placement zone and a catalyst placement zone from top to bottom, which are respectively used for secondary reaction and tertiary reaction. A blank zone is formed between the mesh support portion and the bottom of the outer medium tube.

[0009] Furthermore, the outer medium tube is a quartz tube, the inner medium tube is a corundum tube, the high-voltage needle electrode is a tungsten needle electrode, the low-voltage ring electrode is a stainless steel ring electrode, and the mesh support part is a stainless steel mesh.

[0010] A method for plasma conversion of carbon dioxide and water, using the above-mentioned plasma conversion reactor of carbon dioxide and water, comprises the following steps: Adding a catalyst to the catalyst placement area, adding biomass carbon to the biomass carbon placement area, introducing water to the inlet of the reactor, and introducing carbon dioxide at a gas flow rate of 300-1500 mL / min; applying high voltage to the high-voltage needle electrode, forming an atmospheric pressure glow discharge plasma in the plasma discharge area, and under the action of the atmospheric pressure glow discharge plasma, carbon dioxide and water undergo a first-order reaction to obtain a first-order reaction product; At the same time, under the restraint force of the inner medium tube and the gas flow rate, the atmospheric pressure glow discharge plasma forms a plasma jet, so that the products of the primary reaction, unreacted carbon dioxide and water enter the plasma jet area, and a secondary reaction occurs on the surface of the biomass carbon to obtain the products of the secondary reaction; Under the action of the catalyst, the product of the secondary reaction, unreacted carbon dioxide and water continue to undergo a tertiary reaction to obtain a tertiary reaction product.

[0011] Furthermore, the first-order reaction is CO 2 , H 2 O is excited by vibration and dissociated under the action of plasma. The products of the primary reaction include CO·, O·, H·, OH· free radicals and CO, O 2 , H 2 molecules; the secondary reactions are Boudouard reaction and water-gas reaction. The products of the secondary reactions include H·, CO· free radicals and CO, H 2 molecules; the third-order reaction is CO·free radical, CO and CO 2 The products of the tertiary reaction include acetic acid.

[0012] Furthermore, the catalyst is a hydrophobic iron-zinc catalyst.

[0013] Furthermore, the electron density of atmospheric pressure glow discharge plasma is 10 19 m -3 ~ 10 21 m -3 , the electron temperature is 2eV ~ 4 eV, the gas temperature is 1000~2000 ℃; the temperature of the plasma jet zone is 200~700 ℃.

[0014] Furthermore, the molar ratio of carbon dioxide and water introduced into the reactor is (1:2) to (2:1).

[0015] A system for converting carbon dioxide and water with plasma, comprising a gas supply module, a circuit module, a detection module, a process diagnosis module and the reactor for converting carbon dioxide and water with plasma; A reactor for catalyzing a primary reaction, a secondary reaction and a tertiary reaction between carbon dioxide and water; Gas supply module, including the first CO 2Gas cylinder and water bath, first CO 2 The gas cylinder is connected to the inlet of the reactor via a water bath to provide reaction gas; The circuit module includes an AC high-voltage power supply and a current-limiting resistor, wherein the AC high-voltage power supply is connected to a high-voltage needle electrode via the current-limiting resistor, and the current-limiting resistor is used to limit the discharge current to achieve atmospheric pressure glow discharge. When the voltage is high enough, a non-equilibrium plasma is generated in the plasma discharge region, and a plasma jet is formed in the region where the low-pressure ring electrode is downward. A detection module, including a cold trap bottle, a third flow meter and a gas chromatograph, wherein the outlet of the reactor is connected to the cold trap bottle, the third flow meter and the gas chromatograph in sequence, the cold trap bottle is used to collect the reaction product, the third flow meter is used to obtain the flow of the gas product, and the gas chromatograph is used to detect the type and content of the reaction product; Process diagnostic module, including sampling resistor, oscilloscope, high voltage probe, thermocouple and spectrometer, The low-voltage ring electrode is connected to the ground terminal via a sampling resistor, one end of the oscilloscope is electrically connected to the high-voltage needle electrode via a high-voltage probe, and the other end is electrically connected to the circuit between the low-voltage ring electrode and the sampling resistor; Among them, the oscilloscope is used to obtain the electrical characteristics of the discharge, the high-voltage probe is used to obtain the discharge voltage, and the sampling resistor is used to obtain the discharge current; Thermocouples are set in the blank area of ​​the reactor to obtain the spatial distribution of the axial temperature field of the plasma jet and the temperature of the catalyst placement area.

[0016] Furthermore, the gas supply module further comprises a first flow meter, which is arranged at the CO 2 Between the gas cylinder and the water bath, it is used to adjust the flow of carbon dioxide.

[0017] Furthermore, the gas supply module also includes a second CO 2 Gas cylinder and second flow meter, second CO 2 The gas cylinder is connected between the water bath and the inlet via a second flow meter.

[0018] Compared with the prior art, the positive and progressive effects of the present invention are: The present invention provides a reactor for converting carbon dioxide and water by plasma. By arranging a double medium tube structure, a high-voltage needle electrode is arranged in an inner medium tube, and a low-voltage ring electrode is arranged around the bottom of the inner medium tube, so that atmospheric pressure glow discharge can be generated between the electrodes to realize plasma jet. At the same time, a biomass carbon placement area and a catalyst placement area are arranged in the plasma jet area, and multi-stage catalysis is realized through the synergistic effect between plasma and catalyst, thereby improving the selectivity of target products.

[0019] The present invention provides a method for converting carbon dioxide and water into plasma. By using the method, atmospheric pressure glow discharge plasma can be formed in the plasma discharge zone, so that CO 2 and H 2 The dissociation of O molecules is mainly based on vibration excitation, thus achieving a higher conversion rate; biomass carbon is added to the biomass carbon placement area to inhibit the CO and H 2 The Boudouard reaction and water-gas reaction can increase the CO 2 and H 2 Conversion rate of O, CO and H 2 Yield, solving the CO 2 and H 2 O conversion process 2 The problem of low conversion rate; moreover, a hydrophobic iron-zinc catalyst is added to the catalyst placement area, which can inhibit the water-gas conversion reaction and efficiently catalyze CO·free radicals, CO, CO 2 Hydrogenation to synthesize acetic acid solves the problem of CO 2 and H 2 The problem of low selectivity of liquid products in O conversion.

[0020] The present invention provides a system for converting carbon dioxide and water into plasma, which collects the electrical, thermal and optical characteristics of discharge in real time through an oscilloscope, a thermocouple and a spectrometer to realize online diagnosis of the reaction process, which is beneficial to the regulation of the reaction process; 2 Gas cylinders, flow meters and water baths provide the reaction gas and can regulate CO 2 The flow rate and temperature of the water bath can be directly controlled to control the flow rate and molar ratio of the reaction gas, which is simple, easy and low-cost.

[0021] Furthermore, the system can be connected to a second CO 2 Gas cylinder and second flow meter, through two lines of CO 2 Gas supply mode, one of which is pure CO 2 , all the way CO 2 and H 2 O, the flow rate of the reaction gas and the molar ratio of CO2 and H2O can be more conveniently controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 It is a structural schematic diagram of the reactor of the present invention; Figure 2 It is a structural schematic diagram of the system of the present invention; Figure 3 It is a schematic diagram of the process of the present invention; Figure 4 It is a schematic diagram of the reaction path of the present invention; Figure 5 This is a schematic diagram of the application prospects of the present invention.

[0024] Among them, 1 is the first CO 2 gas cylinder; 2 is the first flow meter; 3 is a water bath; 4 is a reactor; 5 is an AC high voltage power supply; 6 is a current limiting resistor; 7 is a high voltage probe; 8 is an oscilloscope; 9 is a sampling resistor; 10 is a spectrometer; 11 is a thermocouple; 12 is a cold trap bottle; 13 is a gas chromatograph; 14 is a third flow meter; 15 is a second flow meter; 16 is a second CO 2 Gas cylinder.

[0025] 4-1 is an outer medium tube; 4-2 is an inner medium tube; 4-3 is a high-voltage needle electrode; 4-4 is a low-voltage ring electrode; 4-5 is a mesh support; 4-6 is a plasma discharge area; 4-7 is a plasma jet area; 4-8 is a biomass carbon placement area; 4-9 is a catalyst placement area; 4-10 is a blank area. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0033] See also Figure 1 The present embodiment provides a reactor for converting carbon dioxide and water by plasma, comprising an external medium tube 4-1, an internal medium tube 4-2, a high-pressure needle electrode 4-3, a low-pressure ring electrode 4-4 and a mesh support 4-5; the top and bottom of the external medium tube 4-1 are respectively provided with an inlet and an outlet, and the mesh support 4-5 is fixedly arranged on the horizontal cross section of the lower part of the external medium tube 4-1; The inner medium tube 4-2 is shorter than the outer medium tube 4-1 and is coaxially sleeved in the outer medium tube 4-1. The high-voltage needle electrode 4-3 is shorter than the inner medium tube 4-2 and is coaxially sleeved in the inner medium tube 4-2. The top ends of the inner medium tube 4-2 and the high-voltage needle electrode 4-3 are fixedly arranged on the top of the outer medium tube 4-1. The low-voltage ring electrode 4-4 is arranged at the bottom of the inner medium tube 4-2. An annular gap is formed between the high-pressure needle electrode 4-3 and the inner medium tube 4-2, and the annular gap is connected to the inlet for introducing reaction gases, which include carbon dioxide and water; a plasma discharge zone 4-6 is formed between the bottom of the high-pressure needle electrode 4-3 and the top of the low-pressure ring electrode 4-4 for primary reaction; a plasma jet zone 4-7 is formed between the bottom of the inner medium tube 4-2 and the mesh support portion 4-5, and the plasma jet zone 4-7 is provided with a biomass carbon placement zone 4-8 and a catalyst placement zone 4-9 from top to bottom, which are respectively used for secondary reaction and tertiary reaction; a blank zone 4-10 is formed between the mesh support portion 4-5 and the bottom of the outer medium tube 4-1.

[0034] Specifically, the outer medium tube 4-1 is a quartz tube, the inner medium tube 4-2 is a corundum tube, the high-voltage needle electrode 4-3 is a tungsten needle electrode, the low-voltage ring electrode 4-4 is a stainless steel ring electrode, and the mesh support part 4-5 is a stainless steel mesh.

[0035] In this embodiment, the outer diameter of the outer medium tube is 24 mm and the inner diameter is 20 mm, the outer diameter of the inner medium tube is 8 mm and the inner diameter is 6 mm, the diameter of the tungsten needle electrode is 3 mm, and the outer diameter of the stainless steel ring electrode is 8 mm and the aperture is 3 mm.

[0036] See also Figure 2 The present embodiment provides a system for converting carbon dioxide and water into plasma, comprising a gas supply module, a circuit module, a detection module, a process diagnosis module and the above-mentioned reactor 4 for catalyzing the conversion of carbon dioxide and water; the reactor 4 is used to catalyze the primary reaction, the secondary reaction and the tertiary reaction of carbon dioxide and water; the gas supply module comprises a first CO 2 Gas cylinder 1 and water bath 3, first CO 2The gas cylinder 1 is connected to the inlet of the reactor 4 via the water bath 3 to provide the reaction gas; the circuit module includes an AC high-voltage power supply 5 and a current-limiting resistor 6, the AC high-voltage power supply 5 is connected to the high-voltage needle electrode 4-3 via the current-limiting resistor 6, and the current-limiting resistor 6 is used to limit the discharge current to achieve atmospheric pressure glow discharge. When the voltage is high enough, the plasma discharge area 4-6 generates a non-equilibrium plasma and forms a plasma jet in the area where the low-pressure ring electrode 4-4 is downward; the detection module includes a cold trap bottle 12, a third flowmeter 14 and a gas chromatograph 13, and the outlet of the reactor 4 is connected to the cold trap bottle 1 in sequence. 2. A third flowmeter 14 and a gas chromatograph 13, wherein the cold trap bottle 12 is used to collect reaction products, the third flowmeter 14 is used to obtain the flow rate of gas products, and the gas chromatograph 13 is used to detect the type and content of reaction products; a process diagnosis module, comprising a sampling resistor 9, an oscilloscope 8, a high-voltage probe 7, a thermocouple 11 and a spectrometer 10, wherein the low-voltage ring electrode (4-4) is connected to the ground terminal via the sampling resistor (9), one end of the oscilloscope (8) is electrically connected to the high-voltage needle electrode via the high-voltage probe (7), and the other end is electrically connected to the circuit between the low-voltage ring electrode (4-4) and the sampling resistor (9); Among them, the sampling resistor 9 is used to obtain the discharge current, the oscilloscope 8 is used to obtain the electrical characteristics of the discharge, the high-voltage probe 7 is used to obtain the discharge voltage, and the thermocouple 11 is set in the blank area of ​​the reactor 4 to obtain the spatial distribution of the axial temperature field of the plasma jet and obtain the temperature of the catalyst placement area 4-9.

[0037] Specifically, the gas supply module further includes a first flow meter 2, which is arranged at a CO 2 Between the gas cylinder 1 and the water bath 3, it is used to adjust the flow rate of the carbon dioxide.

[0038] Specifically, the gas supply module also includes a second CO 2 The gas cylinder 16 and the second flow meter 15, the second CO 2 The gas cylinder 16 is connected between the water bath and the inlet via the second flow meter 15 .

[0039] In this embodiment, the AC high voltage source has a frequency of 20 kHz, a maximum output voltage of 20 kV, and a maximum output power of 500 W. The current limiting resistor has a resistance of 160 kΩ, and the power of the current limiting resistor should be greater than 400 W to prevent the current limiting resistor from overheating. When the voltage is high enough, based on the current limiting resistor, the high-voltage needle electrode and the low-voltage ring electrode, an atmospheric pressure glow discharge is generated between the electrodes. During the reaction, when the temperature near the catalyst reached 200 °C, the liquid product was collected by a cold trap bottle placed in ice water. During the collection of the liquid product, the thermal conductivity detector (TCD) of a gas chromatograph (Bruker, scion 456-GC) was used to detect the type and content of the gas product online. 5 mL of the liquid product was collected and placed in a headspace injection bottle. The hydrogen flame ionization detector (FID) of the gas chromatograph was used to detect the type and content of the liquid product. The gas product flow rate was monitored in real time by a flow meter. According to the gas product flow rate, reaction time, reaction gas flow rate and product content, the product yield, selectivity and reaction gas conversion rate were calculated. Combined with the discharge power, the energy efficiency can be calculated. The process diagnosis module uses an oscilloscope (Puyuan, DH0924S) to obtain the discharge electrical characteristics; the discharge voltage is collected by a high-voltage probe (Tektronix, P6015A); the voltage across the 50 Ω non-inductive resistor is measured to collect the discharge current, the discharge voltage and current waveforms are analyzed to monitor the discharge form, and the discharge power, electric field strength and other parameters are calculated; a K-type thermocouple is used in combination with a digital display to collect the spatial distribution of the axial temperature field of the plasma jet, and the temperature change near the catalyst is monitored; a spectrometer (Andor, Mechelle 500) and an ICCD (Andor, iStar 334T-18U-63) camera are used in combination to collect the discharge emission spectrum, calculate the electron density, electron excitation temperature, vibration temperature and rotation temperature, and analyze the influence of reaction parameters on active particles. The minimum shutter time of the spectrometer described in this embodiment is less than 2 ns, the spectrum measurement range is 200~900 nm, and the spectrum measurement accuracy reaches 0.05 nm.

[0040] The first flow meter 2 and the second flow meter 15 were both set to 500 mL / min, and the water bath temperature was set to 95 °C (corresponding to CO 2 With H 2 The molar ratio of CO to O is 1:1), and the CO can be changed by adjusting the first flow meter 2, the second flow meter 15 and the temperature of the water bath. 2 and H 2 O flow rate and molar ratio.

[0041] Exemplary, two-way CO 2 When the flow rate is the same and the water bath temperature is set at 90 °C, CO 2 With H 2The molar ratio of CO to O is 2:1; when the water bath temperature is set at 95 °C, 2 With H 2 When the water bath temperature is set at 100 °C, the molar ratio of CO 2 and H 2 The molar ratio of O is 1:2.

[0042] See also Figure 3 This embodiment provides a method for plasma conversion of carbon dioxide and water, using the above reactor, including the following steps: First, treat the hydrophobic iron-zinc catalyst by taking 1 g of the hydrophobic iron-zinc catalyst and stirring it in a mixture of hydrogen and argon (H 2 The catalyst was calcined in a tubular furnace at 350 °C for 10 h in an Ar (Volume ratio: 1:4) atmosphere to obtain a reduced hydrophobic Fe-Zn catalyst, which was then stored in a vacuum.

[0043] Then, 5.5 g of biomass carbon (coconut shell carbon) and the reduced hydrophobic iron-zinc catalyst were loaded into the corresponding area of ​​the reactor, and the CO 2 Gas cylinder and water bath to provide 1000 mL / min CO to the reactor 2 and 1000 mL / min water vapor. After the gas supply is stable, turn on the AC high-voltage power supply, adjust the voltage regulator, apply 12 kV, 20 kHz AC high voltage, and achieve stable atmospheric pressure glow discharge and plasma jet. The reaction gas is synthesized into the target product through a three-stage catalytic reaction.

[0044] For details, see Figure 4 , first-order reaction: the reaction gas enters the reactor from the annular gap between the inner medium tube (corundum tube) and the high-voltage needle electrode (tungsten needle electrode), passes through the plasma discharge zone, and the atmospheric pressure glow discharge plasma is a typical non-equilibrium plasma with an electron density of 10 19 m -3 ~ 10 21 m -3 , the electron temperature is 2 eV ~ 4 eV, the gas temperature is 1000~2000 ℃, CO 2 , H 2 O decomposes in the most energy-efficient vibration-induced dissociation form. Secondary reaction: Boudouard reaction (CO 2 +C→2CO) and water gas reaction (C+H 2 O→CO+H 2 ), which increases CO 2 and H 2 Conversion rate of O, CO and H 2 Yield, biomass carbon and O 2 , O·, etc., thereby inhibiting CO, H2 The compound further increases the CO 2 and H 2 O conversion rate. Third-order reaction: The hydrophobic Fe-Zn catalyst is a core-shell structure, and the Fe-Zn bimetallic catalyst is a porous SiO 2 Shell wrapping, SiO 2 The shell surface is attached with hydrophobic groups, which inhibit the water vapor change reaction (CO+H 2 O→CO 2 +H 2 ) and does not reduce the activity of the catalyst. The CO·free radicals, CO, CO 2 The product then leaves the reactor through a mesh support (stainless steel mesh).

[0045] Specifically, in the plasma discharge region, CO 2 and H 2 O reaction gas is excited by vibration in the plasma and dissociates into free radicals such as CO·, O·, H·, OH·, and CO, O 2 , H 2 On the surface of biomass carbon (coconut shell carbon) in the plasma jet area, carbon reacts with O·, OH·, O 2 , CO 2 , H 2 O and other reactions, while inhibiting CO and H 2 The compound reaction increases the CO 2 , H 2 O conversion rate and CO, H 2 The yield of CO·free radicals, CO, CO 2 Acetic acid is synthesized by hydrogenation while suppressing the water-gas change reaction.

[0046] After testing and calculation, the method provided in this embodiment achieves a CO reduction of more than 7%. 2 Conversion rate, 8% H 2 O conversion and 30% acetic acid selectivity.

[0047] In addition, the preparation method of the hydrophobic iron-zinc catalyst described in this embodiment specifically comprises: 3 ) 3 and Zn(NO 3 ) 2 (Fe:Zn molar ratio is 3:1) hydrate was dissolved in deionized water to prepare a 0.5 mol / L first solution, and 0.5 mol / L K 2 CO 3 Solution, at 60℃ and stirring conditions, K 2 CO 3The solution was added dropwise to the first solution until the pH value of the solution was 7. The mixture was stirred for 1 h, aged for 1 h, centrifuged and the precipitate was washed, dried in an oven at 110 °C for 24 h, ground into powder, and then calcined in a muffle furnace at 350 °C for 6 h to obtain FeZn catalyst. 1 g of FeZn catalyst was ultrasonically dispersed (100 W, 20 min) in 250 mL of ethanol, 2.5 mL of ethyl silicate was added, stirred for 4 h, 5 mL of ammonia (analytical grade) and 20 mL of water were added, stirred for 4 h, centrifuged, the precipitate was washed with ethanol, and dried in an oven at 100 °C for 24 h to obtain FeZn@SiO 2 Catalyst: Take 1 g FeZn@SiO 2 The catalyst was added with 100 mL of n-hexane and 2 mL of trimethylsilyl chloride, and ultrasonicated (100 W, 2 h). The precipitate was washed with n-hexane and dried in a vacuum oven at 80 °C for 6 h to obtain a hydrophobic FeZn catalyst (FeZn@SiO 2 -c).

[0048] By adjusting the molar ratio of Fe and Zn in the hydrophobic Fe-Zn catalyst, discharge power, gas flow rate and CO 2 With H 2 O molar ratio parameter can further increase CO 2 and H 2 The transformation result of O.

[0049] See also Figure 5 The invention uses renewable zero-carbon electricity to drive plasma to capture CO generated by transportation and industry 2 , catalyzing CO 2 and H 2 O is converted into synthesis gas, acetic acid, etc. The synthesis gas can also be converted into acetic acid, etc. through processes such as the Fischer-Tropsch reaction, converting greenhouse gases into fuels and chemical raw materials, achieving energy conversion while reducing carbon emissions.

[0050] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A reactor for plasma conversion of carbon dioxide and water, characterized in that: It comprises an outer medium tube (4-1), an inner medium tube (4-2), a high-voltage needle electrode (4-3), a low-voltage ring electrode (4-4) and a mesh support portion (4-5); the top and bottom of the outer medium tube (4-1) are respectively provided with an inlet and an outlet, and the mesh support portion (4-5) is fixedly arranged on a horizontal cross section at the bottom of the outer medium tube (4-1); The inner medium tube (4-2) is shorter than the outer medium tube (4-1) and is coaxially sleeved in the outer medium tube (4-1); the high-voltage needle-shaped electrode (4-3) is shorter than the inner medium tube (4-2) and is coaxially sleeved in the inner medium tube (4-2); the top ends of the inner medium tube (4-2) and the high-voltage needle-shaped electrode (4-3) are fixedly arranged on the top of the outer medium tube (4-1); the low-voltage ring electrode (4-4) is arranged on the bottom of the inner medium tube (4-2); An annular gap is formed between the high-pressure needle-shaped electrode (4-3) and the inner medium tube (4-2), and the annular gap is connected to the inlet for introducing reaction gas, wherein the reaction gas includes carbon dioxide and water; a plasma discharge zone (4-6) is formed between the bottom of the high-pressure needle-shaped electrode (4-3) and the top of the low-pressure ring-shaped electrode (4-4), for generating a primary reaction; a plasma jet zone (4-7) is formed between the bottom of the inner medium tube (4-2) and the mesh support portion (4-5), and the plasma jet zone (4-7) is provided with a biomass carbon placement zone (4-8) and a catalyst placement zone (4-9) from top to bottom, for generating a secondary reaction and a tertiary reaction, respectively; and a blank zone (4-10) is formed between the mesh support portion (4-5) and the bottom of the outer medium tube (4-1).

2. A plasma conversion reactor for carbon dioxide and water according to claim 1, characterized in that: The outer medium tube (4-1) is a quartz tube, the inner medium tube (4-2) is a corundum tube, the high-voltage needle electrode (4-3) is a tungsten needle electrode, the low-voltage ring electrode (4-4) is a stainless steel ring electrode, and the mesh support part (4-5) is a stainless steel mesh.

3. A method for converting carbon dioxide and water by plasma, characterized in that: The reactor for converting carbon dioxide and water using the plasma of claim 1 or 2 comprises the following steps: A catalyst is added to the catalyst placement area (4-9), biomass carbon is added to the biomass carbon placement area (4-8), water is introduced into the inlet of the reactor, and carbon dioxide is introduced at a gas flow rate of 300-1500 mL / min; high voltage is applied to the high voltage needle electrode, and an atmospheric pressure glow discharge plasma is formed in the plasma discharge area (4-6); under the action of the atmospheric pressure glow discharge plasma, carbon dioxide and water undergo a first-order reaction to obtain a first-order reaction product; At the same time, under the action of the restraining force of the inner medium tube (4-2) and the gas flow rate, the atmospheric pressure glow discharge plasma forms a plasma jet, so that the product of the primary reaction, unreacted carbon dioxide and water enter the plasma jet area (4-7), and a secondary reaction occurs on the surface of the biomass carbon to obtain the product of the secondary reaction; Under the action of the catalyst, the product of the secondary reaction, unreacted carbon dioxide and water continue to undergo a tertiary reaction to obtain a tertiary reaction product.

4. The method for plasma conversion of carbon dioxide and water according to claim 3, characterized in that: The primary reaction is the vibration excitation dissociation of CO2 and H2O under the action of plasma, and the products of the primary reaction include CO·, O·, H·, OH· free radicals and CO, O2, H2 molecules; the secondary reaction is the Boudouard reaction and the water gas reaction, and the products of the secondary reaction include H·, CO· free radicals and CO, H2 molecules; the tertiary reaction is the hydrogenation reaction of CO· free radicals, CO and CO2, and the products of the tertiary reaction include acetic acid.

5. The method for plasma conversion of carbon dioxide and water according to claim 3, characterized in that: The catalyst is a hydrophobic iron-zinc catalyst.

6. The method for plasma conversion of carbon dioxide and water according to claim 3, characterized in that: The electron density of atmospheric pressure glow discharge plasma is 10 19 m -3 ~ 10 21 m -3 , the electron temperature is 2 eV ~ 4 eV, the gas temperature is 1000~2000 ℃; the temperature of the plasma jet zone (4-7) is 200~700 ℃.

7. The method for converting carbon dioxide and water by plasma according to claim 3, characterized in that: The molar ratio of carbon dioxide and water introduced into the reactor (4) is (1:2) to (2:1).

8. A system for converting carbon dioxide and water by plasma, characterized in that: It comprises a gas supply module, a circuit module, a detection module, a process diagnosis module and a reactor (4) for converting carbon dioxide and water into plasma according to claim 1 or 2; A reactor (4) for catalyzing a primary reaction, a secondary reaction and a tertiary reaction between carbon dioxide and water; A gas supply module, comprising a first CO2 gas cylinder (1) and a water bath (3), wherein the first CO2 gas cylinder (1) is connected to an inlet of a reactor (4) via the water bath (3) for providing reaction gas; The circuit module comprises an AC high-voltage power supply (5) and a current-limiting resistor (6), wherein the AC high-voltage power supply (5) is connected to a high-voltage needle electrode (4-3) via the current-limiting resistor (6), and the current-limiting resistor (6) is used to limit the discharge current to achieve atmospheric pressure glow discharge. When the voltage is high enough, a non-equilibrium plasma is generated in the plasma discharge region (4-6), and a plasma jet is formed in the region downward of the low-pressure ring electrode (4-4); A detection module, comprising a cold trap bottle (12), a third flow meter (14) and a gas chromatograph (13), wherein the outlet of the reactor (4) is connected to the cold trap bottle (12), the third flow meter (14) and the gas chromatograph (13) in sequence, the cold trap bottle (12) being used to collect reaction products, the third flow meter (14) being used to obtain the flow rate of gaseous products, and the gas chromatograph (13) being used to detect the type and content of the reaction products; A process diagnosis module includes a sampling resistor (9), an oscilloscope (8), a high voltage probe (7), a thermocouple (11) and a spectrometer (10), The low-voltage annular electrode (4-4) is connected to the ground terminal via a sampling resistor (9); one end of the oscilloscope (8) is electrically connected to the high-voltage needle electrode via a high-voltage probe (7); and the other end is electrically connected to the circuit between the low-voltage annular electrode (4-4) and the sampling resistor (9); The oscilloscope (8) is used to obtain the electrical characteristics of the discharge, the high-voltage probe (7) is used to obtain the discharge voltage, and the sampling resistor (9) is used to obtain the discharge current; The thermocouple (11) is arranged in the blank area (4-10) of the reactor (4) to obtain the spatial distribution of the axial temperature field of the plasma jet and the temperature of the catalyst placement area (4-9).

9. The plasma conversion system of carbon dioxide and water according to claim 8, characterized in that: The gas supply module further comprises a first flow meter (2), which is arranged between the CO2 gas cylinder (1) and the water bath (3) and is used to adjust the flow rate of the introduced carbon dioxide.

10. The plasma conversion system of carbon dioxide and water according to claim 9, characterized in that: The gas supply module further comprises a second CO2 gas cylinder (16) and a second flow meter (15), and the second CO2 gas cylinder (16) is connected between the water bath and the inlet via the second flow meter (15).

Images