An in-situ diffuse reflectance infrared device for low temperature plasma catalytic reaction mechanism research

Abstract

The application relates to an in-situ diffuse reflectance infrared device for low-temperature plasma catalytic reaction mechanism research. The device comprises a high-voltage electrode, a gas inlet end, a reaction pool base, a coaxial dielectric barrier discharge quartz tube, a dome, a ground electrode and a gas outlet end; the high-voltage electrode and the gas inlet end are connected with the inlet end of the reaction pool base through a T-shaped polytetrafluoroethylene tee joint; the coaxial dielectric barrier discharge quartz tube is inserted and fixed in the reaction pool base through a reserved groove; the coaxial dielectric barrier discharge quartz tube is filled with a catalyst layer; the dome is matched with the reaction pool base through a guide rail sliding block and a fixing screw, and a closed hollow structure is formed; the ground electrode and the gas outlet end are connected with the outlet end of the reaction pool base through a T-shaped polytetrafluoroethylene tee joint. The synergistic effect between the plasma generated by the dielectric barrier discharge and the catalytic catalyst is observed by using the in-situ diffuse reflectance infrared signal, which provides a feasible means for deeply understanding the plasma catalytic reaction process.

Description

Technical Field

[0001] This invention relates to an in-situ diffuse reflection infrared device for low-temperature plasma synergistic catalytic reaction generated by dielectric barrier discharge, mainly including the structural design and application of the infrared in-situ reaction device. Technical Background

[0002] Low-temperature plasma is a state of matter in which gas molecules are ionized to a certain degree, resulting in a balance between the number of positive and negative charges. This ionized gas is mainly composed of electrons, ions, free radicals, and excited-state atoms and molecules. Due to the different chemical activities of these substances, low-temperature plasma can be used in many fields such as chemical synthesis and pollutant purification. To further improve reaction efficiency, low-temperature plasma is often combined with catalysts to form plasma catalysis technology.

[0003] In plasma catalysis, to enhance the synergistic effect between plasma and catalyst, the catalyst is typically placed within the plasma region. However, due to the complexity of plasma catalytic reactions, a direct and effective detection method is currently lacking, and the reaction mechanism remains unclear. Diffuse reflectance infrared spectroscopy is a widely used in-situ technique that can obtain key surface reaction information and reaction processes by tracking and characterizing adsorbed species on the catalyst surface, thereby deepening our understanding of the catalytic reaction mechanism. For plasma catalysis, existing commercial in-situ diffuse reflectance infrared reaction cells cannot meet the requirements for plasma catalysis because they cannot achieve reaction observation under plasma discharge conditions. Some studies have used self-designed transmission infrared devices, but these suffer from problems such as difficulties in catalyst tableting and loading, and transmission signal distortion. For example, the in-situ transmission infrared device in CN 114199774 A has a long infrared path, resulting in the infrared signal being dominated by gas signals within the cavity. Other studies have introduced high-voltage electrodes through the viewing window into commercial thermocatalytic in-situ infrared cells and grounded the entire reactor for in-situ discharge observation. However, such improvements are difficult to accurately control the discharge position and cannot stably observe the synergistic effect of plasma-catalysis. Some plasma catalytic in-situ diffuse reflection devices have design defects that cause changes in the plasma discharge mode during the reaction. For example, the in-situ diffuse reflection device in CN109187410B may cause its discharge mode to transition from dielectric barrier discharge to arc discharge due to the placement of its high-voltage and low-voltage stages, resulting in the research results not reflecting the true information.

[0004] This invention proposes an in-situ diffuse reflectance infrared spectroscopy characterization method and apparatus for plasma catalytic reactions under insulating conditions, through in-situ cell structure design and optimization of different component materials. This invention improves upon the basic dimensions of commercial in-situ cells to meet plasma discharge requirements, ensuring safe insulation while coupling a dielectric barrier discharge unit into the in-situ reaction cell for clear observation of the plasma catalytic reaction process. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an in-situ diffuse reflection infrared device suitable for plasma catalytic reactions using dielectric barrier discharge, which can perform in-situ observation of the plasma-induced chemical reaction process on the catalyst surface during the plasma catalytic reaction.

[0006] The specific technical solution of the present invention is as follows:

[0007] A plasma catalytic in-situ diffuse reflection infrared device using dielectric barrier discharge (PTD) comprises seven main components: a high-voltage electrode, an inlet, a reaction cell substrate, a coaxial PDD quartz tube, a dome, a ground electrode, and an outlet. The high-voltage electrode and the inlet are connected to the inlet of the reaction cell substrate via a T-shaped PTFE tee. The coaxial PDD quartz tube is inserted into and fixed to the reaction cell substrate via a pre-drilled groove. The coaxial PDD quartz tube is filled with a catalyst layer. The dome is fitted to the reaction cell substrate via a guide rail slider and fixing screws, forming a closed hollow structure. The ground electrode and the outlet are connected to the outlet of the reaction cell substrate via a T-shaped PTFE tee. The seven main components can be disassembled and assembled individually, offering high flexibility. Experimental parameters such as the discharge gap, discharge region volume, and reaction space velocity can be flexibly adjusted according to experimental needs, enabling reaction observation under different conditions. The infrared window is fixed to the dome with an annular nut.

[0008] Furthermore, the reaction tank substrate is made of polyetheretherketone (PEEK) special polymer material, which is an electrical insulating material that is resistant to high temperature and chemical corrosion.

[0009] Furthermore, after the high-voltage electrode passes through the polytetrafluoroethylene tee, it extends vertically into the dielectric barrier discharge quartz tube in an L-shape, slightly below the height of the quartz tube, to avoid the formation of an electric arc between the high-voltage electrode and the ground electrode, thereby changing the discharge mode.

[0010] Furthermore, the high-voltage electrode metal material is copper and is coaxial with the quartz tube; the ground electrode material is a copper mesh tightly wound around the outer wall of the quartz tube, and the winding position is below the top of the quartz tube to avoid arc discharge.

[0011] Furthermore, the reaction gas entering from the lower end of the dielectric barrier discharge quartz tube fills the cavity after passing through the catalyst layer, and the ground electrode and the gas outlet are connected to the threaded outlet reserved in the reaction cell through a T-shaped polytetrafluoroethylene tee, and the tail gas leaves the reaction cell through the outlet end.

[0012] Furthermore, the infrared window is made of potassium bromide (KBr), and a transparent quartz window is reserved at the front to observe the discharge reaction inside the cavity and the position of diffuse infrared light reflection, so as to better adjust the signal and observe the discharge reaction.

[0013] Furthermore, infrared light enters the reaction chamber through the infrared window and irradiates the upper surface of the catalyst filled in the dielectric barrier discharge quartz tube. Its diffuse reflection source is absorbed by the infrared detector through the opposing infrared window.

[0014] Furthermore, after fixing the reaction device on the workbench, the intensity of the infrared diffuse reflection signal is adjusted by adjusting the vertical height of the reaction cell.

[0015] Furthermore, the catalyst layer is a Ni-based supported catalyst.

[0016] The plasma catalytic in-situ diffuse reflection infrared device using the dielectric barrier discharge method employs high-temperature resistant insulating materials for the inlet and outlet components of the reaction cell and the reaction cell substrate, providing high insulation and heat resistance stability for long-term reactions; the high-voltage electrode and the ground electrode are copper rods (wires) with good electrical conductivity; and the dielectric material for the plasma discharge region is quartz.

[0017] The technical structure principle of this invention is as follows: One end of a polytetrafluoroethylene (PTFE) tee is connected to the inlet of the plasma in-situ reaction cell, and the remaining two ports are used to insert one high-voltage electrode and the other to connect to the reaction gas. The reaction gas and the high-voltage electrode enter from the bottom of the reaction cell and are introduced into the intermediate cavity at a vertical angle. The quartz tube is directly inserted into the fixed groove reserved in the reaction cell and is coaxial with the vertical gas channel and the high-voltage electrode. After the gas exits through the quartz tube, it fills the cavity and is then led out through one end of the PTFE tube connected to the outlet of the reaction cell. The ground electrode is tightly wrapped around the outer wall of the quartz tube, and the copper wire is led out through the other end of the PTFE tube connected to the outlet of the reaction cell. The catalyst is filled inside the quartz tube, with a small amount of quartz wool filled at the bottom to reduce the amount of catalyst, and the catalyst at the top should be compacted. The reaction cell is fixed on the lifting worktable, and the optimal diffuse reflection height is adjusted by rotating the lifting knob to obtain the optimal reaction signal.

[0018] Analysis of the key technical points of the present invention: (1) The high voltage electrode should be coaxial with the quartz medium in the discharge area, otherwise uneven discharge will occur; (2) The height of the high voltage electrode should be slightly lower than the height of the dielectric quartz tube, otherwise arc discharge will occur between the high voltage electrode and the ground electrode, thus changing the discharge form; (3) The ground electrode winding height should be slightly lower than the height of the dielectric quartz tube, otherwise arc discharge will occur between the high voltage electrode and the ground electrode, thus changing the discharge form; (4) The catalyst should be granulated and then filled, preferably with a particle size of 40-60 mesh. If the filled catalyst is in powder form, the acceleration of the airflow by the plasma will cause the powder catalyst to splash, thus affecting the stability of the infrared signal. If the particle size is too large, the diffuse reflection signal is weak, affecting the acquisition of the spectral signal.

[0019] The workflow of this invention is as follows: First, experimental parameters, such as the discharge gap, are selected to determine the diameter of the high-voltage electrode metal rod and the catalyst bed filling height. One end of the inlet tee is connected to the reaction tank substrate, and the remaining two ends are connected to the gas inlet and the high-voltage electrode, respectively. The dielectric quartz tube is coaxially inserted into the reaction tank substrate with the high-voltage electrode, and the ground electrode is led out from the tee at the reaction tank outlet. A small amount of quartz wool is first filled at the bottom of the quartz tube, followed by the catalyst, and the upper surface of the catalyst should be flattened. The dome is fixed to the reaction tank substrate by a slider guide rail to form a sealed cavity reaction space. The reaction gas enters the cavity after passing through the plasma catalytic discharge area and is then led out from the tee at the reaction tank substrate outlet. Before the reaction, the catalyst should be pretreated by heating under argon conditions with an external infrared irradiation lamp for 1 hour, followed by argon plasma discharge treatment. The purpose of the above two steps is to remove impurities adsorbed on the catalyst surface to ensure a flat baseline for the collected data. During the reaction, the concentration of active species can be adjusted by adjusting the voltage. The continuous infrared signal during the reaction is collected by the detector to form a continuous infrared spectrum.

[0020] Compared with the prior art, the present invention has the following advantages: (1) Most current plasma catalytic reaction mechanism studies detect gas components at the reactor outlet to infer the reaction process. The in-situ reaction device designed in this invention enables in-situ observation of the synergistic effect of plasma and catalyst; (2) Some in-situ plasma infrared reaction devices are transmission reaction structures with long infrared light paths in the reaction chamber, so most of the collected signals are reaction gas signals outside the plasma region, i.e., mostly gas signals. Therefore, it is difficult to reflect the surface reaction process of plasma catalytic reaction. The present invention adopts an in-situ diffuse reflection method, which reduces the optical path of the infrared signal in the reaction chamber and maximizes the presentation of the chemical reaction signal on the catalyst surface; (3) Some plasma catalytic in-situ diffuse reflection devices have design defects, which lead to changes in the plasma discharge mode during the reaction process, such as transitioning from dielectric barrier discharge to arc discharge. The present invention takes this factor into consideration during the design process, avoids changes in discharge type from the design perspective, ensures the stability of plasma dielectric barrier discharge, and thus ensures the stability and reliability of infrared signals. Attached Figure Description

[0021] Figure 1 This is a top-cross-sectional view of the plasma catalytic in-situ diffuse reflection infrared device of the dielectric barrier discharge method of the present invention;

[0022] Figure 2 This is a 3D schematic diagram of the plasma catalytic in-situ diffuse reflection infrared device of the dielectric barrier discharge method of the present invention;

[0023] Figure 3 This is a schematic diagram of the gas flow direction in the dielectric barrier discharge method of the present invention;

[0024] Figure 4 This is the infrared spectrum of the plasma catalytic in-situ diffuse reflection infrared device of the dielectric barrier discharge method of the present invention applied to a gas-phase catalytic reaction.

[0025] In the diagram: 1. High-voltage electrode, 2. Inlet, 3. Reactor base, 4. Quartz tube, 5. Dome, 6. Infrared window, 7. Ground electrode, 8. Outlet, 9. Catalyst layer, 10. Guide rail slider. Detailed Implementation

[0026] The specific embodiments and examples of the present invention will be described in detail below with reference to the accompanying drawings. The specific embodiments described are only used to explain the present invention and are not intended to limit the specific embodiments of the present invention.

[0027] The following embodiments adopt the following structure: Figure 1 and Figure 2As shown, a dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device includes a high-voltage electrode 1, an inlet end 2, a reaction cell substrate 3, a coaxial dielectric barrier discharge quartz tube 4, a dome 5, a ground electrode 7, and an outlet end 8. The high-voltage electrode 1 and the inlet end 2 are connected to the inlet end of the reaction cell substrate 3 via a T-shaped polytetrafluoroethylene (PTFE) tee. The coaxial dielectric barrier discharge quartz tube 4 is inserted into and fixed to the reaction cell substrate 3 through a pre-reserved groove. The coaxial dielectric barrier discharge quartz tube 4 is filled with a catalyst layer 9. The dome 5 is fitted to the reaction cell substrate 3 via a guide rail slider 10 and fixing screws, forming a closed hollow structure. The ground electrode 7 and the outlet end 8 are connected to the outlet end of the reaction cell substrate 3 via a T-shaped PTFE tee. This embodiment also includes an infrared window 6, which is fixed to the dome 5 by an annular nut. The reaction cell substrate is made of polyetheretherketone (PEEK) special polymer material, which is an electrically insulating material with high temperature resistance and chemical corrosion resistance. After passing through a PTFE tee, the high-voltage electrode 1 extends vertically into the dielectric barrier discharge quartz tube 4 in an L-shape, slightly below the height of the quartz tube 4, to avoid arcing between the high-voltage electrode and the ground electrode, thus preventing changes in the discharge pattern. The high-voltage electrode 1 is made of copper and is coaxial with the quartz tube 4; the ground electrode 7 is made of copper mesh, tightly wound around the outer wall of the quartz tube 4, with the winding position below the top of the quartz tube 4 to prevent arcing. The reaction gas entering from the lower end of the dielectric barrier discharge quartz tube 4 fills the cavity after passing through the catalyst layer 9, and the ground electrode 7 and the gas outlet 8 are connected to the threaded outlet of the reaction cell via a T-shaped PTFE tee. The exhaust gas leaves the reaction cell through the outlet 8. The infrared window 6 is made of potassium bromide (KBr), and a transparent quartz window is reserved at the front to observe the discharge reaction and the position of diffuse infrared light reflection within the cavity, allowing for better signal adjustment and observation of the discharge reaction. Infrared light enters the reaction chamber through the infrared window 6 and irradiates the upper surface of the catalyst filled in the dielectric barrier discharge quartz tube 4. Its diffuse reflection source is absorbed by the infrared detector through the opposing infrared window. After the reaction apparatus is fixed on the worktable, the intensity of the infrared diffuse reflection signal is adjusted by regulating the vertical height of the reaction cell. In this embodiment, the catalyst is placed inside the reaction cell, and the reactant gas passes through the catalyst layer before rising and fills the reaction cell chamber. The reactant gas generates plasma under the action of a high-voltage electric field. The adsorbed intermediate species generated during the plasma-catalyzed surface reaction selectively absorb infrared light of different wavelengths, and the infrared diffuse reflection signal is transmitted to the infrared detector. This invention provides an important in-situ characterization method for the study of the mechanism of low-temperature plasma catalytic reactions such as ammonia synthesis, selective methane oxidation, carbon dioxide hydrogenation, and volatile organic compound oxidation. Furthermore, this invention is simple in design, easy to operate, and safe to use.

[0028] Example 1

[0029] Application of a dielectric barrier discharge plasma catalytic in-situ diffuse reflection infrared device in the partial oxidation reaction of methane catalyzed by plasma.

[0030] Experimental parameters: High-voltage AC power supply was used as the input power supply, the discharge voltage was 10kV, the discharge frequency was 10kHz; the working gas was methane and oxygen, the ratio of methane to oxygen was 5:1, argon was used as the balance gas, the total gas flow rate was controlled at 30ml / min, and the catalyst loading was 0.3g.

[0031] Complete experimental procedure: First, the Ni-based supported catalyst is ground and sieved, with an optimal mesh size of 40-60. The granulated catalyst is pretreated under an infrared lamp for 30 minutes. Then, the catalyst is filled into a quartz tube, with the lower part of the quartz tube pre-filled with quartz wool to reduce the amount of catalyst required. The upper end of the catalyst is flattened and level with the height of the quartz tube. The dome is then sealed. After checking the airtightness of each connection, argon gas at a flow rate of 30 ml / min is introduced into the reaction tank. The working gas enters the reaction tank base 3 through inlet 2, enters the quartz tube 4 through a right-angle pipe, then passes through the catalyst bed 9 and enters the sealed cavity formed by the reaction tank base and the dome. Finally, it exits the reaction tank from the outlet 8 of the PTFE tee connected to the outlet end of the reaction tank base. The high-voltage electrode 1 enters the reaction tank through the PTFE tee connected to the inlet of the reaction tank base, then rises vertically into the quartz tube 4, coaxial with the quartz tube. The ground electrode 7 is tightly wound around the outer wall of the quartz tube and leads out through a PTFE tee at the outlet end of the reaction cell base. All gas inlets and outlets, as well as high and low voltage lines, are secured with sealing elements and threaded seals. After argon gas fills the reaction chamber, the voltage is increased to 8kV for 30 minutes of discharge. The generated argon plasma promotes the desorption of impurities adsorbed on the catalyst surface, resulting in a more stable infrared baseline. After argon plasma desorption is complete, infrared baseline acquisition is performed. After baseline acquisition, reaction gases methane and oxygen are introduced. Once adsorption is saturated, discharge begins at 10kV, and infrared spectra are acquired in real time. Simultaneously, the discharge within the chamber is observed in real time through a high-transparency window positioned directly in front of the reaction cell.

[0032] Figure 4 This is the infrared spectrum of the plasma-catalyzed partial oxidation reaction of methane under a 10 kV discharge condition. With the plasma off, only adsorbed methane and hydroxyl signals on the catalyst surface can be observed. At the instant the plasma is turned on, plasma-excited chemically active substances adsorb onto the catalyst surface and undergo surface reactions, generating reaction intermediate signals. Specifically, this is manifested as: adsorbed methane (30-20 cm⁻¹) -1 The signal decreases, and the adsorbed methanol (1007-1102 cm⁻¹) is in the lower position. -1 ), methoxy (1148cm) -1 CO bond stretching vibration (1257cm) -1), formate (1580cm) -1 ), aldehyde group (1730cm) -1 ), carbon monoxide (1943, 2094 cm⁻¹) -1 ) and carbon dioxide (2340cm) -1 The signal gradually strengthens, indicating that under the synergistic effect of plasma and catalyst, methane is dehydrogenated to produce methyl groups, which then undergo oxygenation to form methoxy groups, followed by hydrogenation to form methanol, which is then desorbed. Throughout the reaction, methane is partially oxidized to methanol, formaldehyde, and formic acid—three liquid products at room temperature—along with a small amount of fully oxidized products.

[0033] Example 2

[0034] Application of a dielectric barrier discharge plasma catalytic in-situ diffuse reflection infrared device in the plasma catalytic complete oxidation reaction of methane.

[0035] Experimental parameters: High-voltage AC power supply was used as the input power supply, the discharge voltage was 9kV, the discharge frequency was 10kHz; the reaction gas was 1% CH4 / 20% O2 / N2 gas, the total gas flow rate was controlled at 30ml / min, and the catalyst loading was 0.3g.

[0036] Complete experimental procedure: First, the Ni-based supported catalyst was ground and sieved, with an optimal mesh size of 40-60 mesh. The granulated catalyst was pretreated under an infrared lamp for 30 minutes. Then, the catalyst was filled into a quartz tube, with the lower part of the quartz tube pre-filled with quartz wool to reduce the amount of catalyst required. The upper end of the catalyst was flattened and leveled with the height of the quartz tube. The dome was then sealed. After checking the airtightness of all connections, argon gas was introduced into the reaction cell at a rate of 30 ml / min, and an 8 kV voltage was applied to remove impurities adsorbed on the catalyst surface. A baseline was collected. After the baseline was flattened, 1% CH4 / 20% O2 / N2 gas was introduced, and the plasma power supply was turned on for a 9 kV discharge. The infrared spectrum was then acquired in real time.

[0037] The infrared spectrum shows: adsorbed methane (3020 cm⁻¹) -1 ), carbon monoxide (1943, 2094 cm) -1 ), and carbon dioxide (2340cm) -1 ), adsorbed hydroxyl groups (1748cm) -1 ), carbonates (1470cm) -1 ) and carboxylates (1595cm -1 The peak indicates that methane was oxidized to CO on the catalyst surface. x It also produced small amounts of difficult-to-decompose intermediate byproducts, carbonates and carboxylates.

[0038] Example 3

[0039] Application of a dielectric barrier discharge plasma catalytic in-situ diffuse reflection infrared device in plasma catalytic methanol degradation reaction.

[0040] Experimental parameters: High-voltage AC power supply was used as the input power source, with a discharge voltage of 10kV and a discharge frequency of 10kHz; the reaction gas was 300ppm CH3OH / Air gas, the total gas flow rate was controlled at 30ml / min, and the catalyst loading was 0.3g.

[0041] Complete experimental procedure: First, the Ni-based supported catalyst was ground and sieved, with an optimal mesh size of 40-60. The granulated catalyst was pretreated under an infrared lamp for 30 minutes. Then, the catalyst was filled into a quartz tube, with the lower part of the quartz tube pre-filled with quartz wool to reduce the amount of catalyst required. The upper end of the catalyst was flattened and level with the height of the quartz tube. The dome was then sealed. After checking the airtightness of all connections, argon gas was introduced into the reaction cell, and an 8kV voltage discharge was applied to remove impurities adsorbed on the catalyst surface. A baseline was acquired. After the baseline was flattened, 300ppm CH3OH / Air gas was introduced for adsorption for a period of time. Once the signal stabilized, the plasma power supply was turned on for a 10kV discharge, and the infrared spectrum was acquired in real time.

[0042] The infrared spectrum shows that the adsorbed hydroxyl groups (3242 cm⁻¹) -1 ), methoxy (1148cm) -1 ), formate (1633, 1498, 1350, 1205cm) -1 The presence of peaks such as ) indicates that methanol was oxidized to carbon dioxide on the catalyst surface, with a small amount of intermediate formate produced.

Claims

1. A dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device, characterized in that, It includes a high-voltage electrode (1), an inlet end (2), a reaction cell base (3), a coaxial dielectric barrier discharge quartz tube (4), a dome (5), a ground electrode (7), and an outlet end (8); The high-voltage electrode (1) and the air inlet (2) are connected to the inlet end of the reaction tank substrate (3) through a T-shaped polytetrafluoroethylene tee; The coaxial dielectric barrier discharge quartz tube (4) is inserted into and fixed to the reaction cell substrate (3) through a reserved groove; the coaxial dielectric barrier discharge quartz tube (4) is filled with a catalyst layer (9); The dome (5) and the reaction tank base (3) are connected by a guide rail slider (10) and fixing screws to form a closed hollow structure; The ground electrode (7) and the gas outlet (8) are connected to the outlet end of the reaction tank substrate (3) through a T-shaped polytetrafluoroethylene tee; After the high voltage electrode (1) passes through the polytetrafluoroethylene tee, it extends vertically into the dielectric barrier discharge quartz tube (4) in an L-shape and is slightly lower than the height of the quartz tube (4) to avoid the formation of an electric arc between the high voltage electrode and the ground electrode, thereby changing the discharge mode. The working gas enters the reaction tank base (3) from the inlet end (2), enters the quartz tube (4) through the right-angle pipe, then enters the sealed cavity formed by the reaction tank base and the dome through the catalyst layer (9), and finally leaves the reaction tank base from the outlet end (8) of the polytetrafluoroethylene tee connected to the outlet end of the reaction tank base. The high-voltage electrode (1) enters the reaction tank base from the polytetrafluoroethylene tee connected to the inlet of the reaction tank base, and then rises vertically into the quartz tube (4). The high-voltage electrode (1) is made of copper and is coaxial with the quartz tube (4); the ground electrode (7) is made of copper mesh, which is tightly wrapped around the outer wall of the quartz tube (4) and the wrapping position is below the top of the quartz tube (4) to avoid arc discharge. The reaction gas that enters from the lower end of the dielectric barrier discharge quartz tube (4) fills the cavity after passing through the catalyst layer (9), and the ground electrode (7) and the outlet (8) are connected to the threaded outlet reserved in the reaction cell through a T-type polytetrafluoroethylene tee. The tail gas leaves the reaction cell through the outlet (8). Infrared light enters the reaction chamber through the infrared window (6) and irradiates the upper surface of the catalyst filled in the dielectric barrier discharge quartz tube (4). Its diffuse reflection light source is absorbed by the infrared detector through the opposing infrared window. The high-voltage electrode (1) is made of copper and is coaxial with the quartz tube (4); the ground electrode (7) is made of copper mesh, which is tightly wrapped around the outer wall of the quartz tube (4) and the wrapping position is below the top of the quartz tube (4) to avoid arc discharge.

2. The dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device according to claim 1, characterized in that, It also includes an infrared window (6); the infrared window (6) is fixed to the dome (5) by an annular nut.

3. The dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device according to claim 1, characterized in that, The substrate of the reaction tank is made of polyether ether ketone (PEEK) special polymer material, which is an electrical insulating material that is resistant to high temperature and chemical corrosion.

4. The dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device according to claim 1, characterized in that, The infrared window (6) is made of potassium bromide (KBr), and a transparent quartz window is reserved in front to observe the discharge reaction in the cavity and the position of diffuse reflection of infrared light, so as to better adjust the signal and observe the discharge reaction.

5. The dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device according to claim 1, characterized in that, After fixing the reaction device on the workbench, the intensity of the infrared diffuse reflection signal is adjusted by adjusting the vertical height of the reaction cell.

6. The dielectric barrier discharge low-temperature plasma catalytic in-situ diffuse reflection infrared device according to claim 1, characterized in that, The catalyst layer is a Ni-based supported catalyst.

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