An in-situ infrared reaction device for low-temperature plasma catalytic reaction

Abstract

The utility model discloses a kind of in-situ infrared reaction devices for low-temperature plasma catalytic reaction, the device includes reaction pool base and conical dome, the conical dome cover is arranged above reaction pool base, the gas inlet and gas outlet for being used to communicate sample cell are processed on base, sample cell is vertically arranged in the center groove of reaction pool base, the sample cell is provided with center electrode, quartz tube and outer wall electrode from inside to outside, the outer sleeve of the center electrode is provided with quartz tube, the middle part of center electrode is provided with annular gasket, the area surrounded by annular gasket and quartz tube is the container of catalyst. The separation design in this space of the utility model makes that discharge device and infrared light path are completely isolated, avoids the physical obstruction of electrode assembly to light path, and guarantees the acquisition of high-quality, high signal-to-noise ratio infrared spectrogram.

Description

Technical Field

[0001] This utility model relates to the field of infrared spectroscopy instrument accessories and instrument analysis technology, and more particularly to an in-situ infrared reaction cell characterization device for low-temperature plasma catalytic reactions. Background Technology

[0002] In recent years, low-temperature plasma catalysis technology has shown great application potential in environmental remediation, energy and chemical industries due to its advantages such as mild reaction conditions, rapid start-up and shutdown, and simple equipment. To deeply understand its reaction mechanism, there is an urgent need to develop technologies capable of real-time, in-situ monitoring of the dynamic changes in catalyst surface species. In-situ infrared spectroscopy can provide rich information on surface species, intermediate products, and molecular structures during the reaction process, making it a powerful tool for studying catalytic reaction mechanisms. However, combining it with the low-temperature plasma environment requiring high-voltage discharge necessitates consideration of numerous issues, such as electric field introduction and optical path design.

[0003] To achieve in-situ characterization of chemical reactions, various in-situ reaction devices have been disclosed in the prior art.

[0004] Chinese invention patent application CN118150602 A discloses an in-situ synchrotron radiation characterization device for low-temperature plasma catalytic reactions. This device, through the design of an in-situ reaction cell containing a high-voltage electrode and a ground electrode, achieves the combined use of low-temperature plasma catalysis and in-situ X-ray absorption fine structure spectroscopy (XAFS). This invention provides an important approach for in-situ characterization in a plasma environment; however, it uses a synchrotron radiation source, aiming to obtain local atomic and electronic structure information of the catalyst, rather than the molecular vibrational information provided by infrared spectroscopy. Therefore, its optical path design, window material, and overall structure are not suitable for infrared spectroscopy detection requirements.

[0005] Chinese invention patent application CN109283151 A discloses a device for realizing dielectric barrier discharge in an in-situ infrared analysis apparatus. This scheme achieves simultaneous analysis of plasma discharge and infrared spectroscopy by modifying the diffuse reflection in-situ cell and inserting a high-voltage electrode at an angle above the sample cell from the observation window. However, on the one hand, the high-voltage electrode and the ground electrode are not parallel, resulting in an uneven electric field distribution. This leads to significant spatial differences in plasma density and reactivity, thus affecting the accuracy of the infrared spectral data. On the other hand, the angled electrode and its fixing structure may interfere with the infrared light collection path, affecting signal quality.

[0006] Therefore, there is still a lack in the field of a low-temperature plasma in-situ infrared reaction device that can provide a more uniform plasma discharge environment and does not interfere with the infrared light path, so as to meet the need for precise research on catalytic reaction mechanisms. Utility Model Content

[0007] The objective of this utility model can be achieved through the following technical solutions:

[0008] An in-situ infrared reaction device for low-temperature plasma catalytic reaction is disclosed. The device includes a reaction cell base and a conical dome, with the conical dome covering the reaction cell base. The base is machined with a gas inlet and a gas outlet for connecting a sample cell. The sample cell is vertically arranged in a central groove in the reaction cell base. The sample cell is provided with a central electrode, a quartz tube, and an outer wall electrode from the inside out. The quartz tube is sleeved on the outside of the central electrode, and an annular gasket is provided in the middle of the central electrode. The area enclosed by the annular gasket and the quartz tube is a container for the catalyst.

[0009] In this utility model, the base is also provided with sealing screw holes and bolts that are matched and connected to the sample chamber of the external infrared spectrometer.

[0010] In this utility model, the conical dome is pressed onto the base by the fixing plates on both sides of the base, and four conical dome fixing bolts pass through the fixing plates and are screwed into the pre-set conical dome fixing screw holes on the base.

[0011] In this utility model, three windows are symmetrically arranged on the conical dome, which are used as the infrared light entrance window, exit window, and observation window, respectively.

[0012] The plasma generator includes a high-voltage power supply, a voltage regulator, a power cord, a voltage regulator output line, a grounding wire, and electrode connection lines.

[0013] This utility model has the following beneficial effects:

[0014] This invention employs a coaxial discharge structure, allowing the plasma to act more uniformly on the catalyst bed. The resulting in-situ infrared spectral data better represents the true structure-activity relationship of the sample, leading to higher accuracy in the analysis results. The infrared beam of this invention detects the sample surface through a conical dome window at the top using diffuse reflection, while the plasma discharge device is completely confined within the sample cell. This spatial separation design completely isolates the discharge device from the infrared light path, avoiding physical obstruction of the light path by the electrode components and ensuring the acquisition of high-quality, high signal-to-noise ratio infrared spectra. Attached Figure Description

[0015] Figure 1 This is a front view of the in-situ reaction tank according to an embodiment of this utility model;

[0016] Figure 2 This is a cross-sectional view of the in-situ reaction tank after the catalyst is filled according to an embodiment of this utility model;

[0017] Figure 3This is a top view of the in-situ reaction tank according to an embodiment of this utility model;

[0018] Figure 4 This is a top view of the base of the in-situ reaction tank according to an embodiment of the present invention;

[0019] Figure 5 This is a side view of the base of the in-situ reaction tank according to an embodiment of the present invention;

[0020] Among them, 1 is a conical dome, 2 is the reaction cell base, 3 is a window, 4 is a fixing bolt, 5 is a conical dome fixing plate, 6 is a sealing screw hole for matching and connecting the reaction cell with the infrared spectrometer, 7 is a bolt for matching and connecting the reaction cell with the infrared spectrometer, 8 is a gas inlet, 9 is a gas outlet, 10 is a central electrode, 11 is a quartz tube, 12 is an outer wall electrode, 13 is a support pad, 14 is a catalyst, and 15 is a conical dome fixing screw hole. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0022] like Figures 1 to 5 This invention provides an in-situ infrared reaction device for low-temperature plasma catalytic reactions, the core of which is an in-situ reaction cell. The in-situ reaction cell mainly includes a reaction cell base 2, a conical dome 1 covering the base 2, a fixing assembly for fixing the two, and a sample cell disposed inside the base 2.

[0023] like Figure 4 and Figure 5 As shown, the reaction cell base 2 is preferably made of a material with excellent electrical insulation and chemical stability, such as polytetrafluoroethylene (PTFE), and is precision-machined in one piece. This design ensures the structural stability and airtightness of the device under low-temperature plasma high-voltage discharge conditions. The base 2 is machined with a gas inlet 8 and a gas outlet 9 for connecting to the sample cell. Simultaneously, the base 2 is also equipped with sealing screw holes 6 and bolts 7 for matching and connecting to the sample chamber of an external infrared spectrometer, used to stably and sealingly fix the entire in-situ reaction cell in the optical path of the spectrometer.

[0024] Please see Figure 1 and Figure 3 A conical dome 1 is positioned above the reaction cell base 2. For sealing and fixation, the conical dome 1 is pressed against the base 2 by fixing plates 5 on both sides, and four conical dome fixing bolts 4 pass through the fixing plates 5 and are screwed into pre-set conical dome fixing screw holes 15 on the base 2. Three windows 3 are symmetrically arranged on the conical dome 1; two windows serve as the infrared light entrance and exit windows, and the other serves as an observation window, facilitating observation of the reaction and discharge within the sample cell.

[0025] Please see Figure 2 The core innovation of this utility model lies in its unique sample cell structure. The sample cell is vertically positioned within the central groove of the reaction cell base 2. From the inside out, the sample cell is equipped with a central electrode 10, a quartz tube 11, and an outer wall electrode 12. The quartz tube 11 is fitted around the central electrode 10, and an annular gasket 13 is located in the center of the central electrode 10. The area enclosed by the annular gasket 13 and the quartz tube 11 serves as a catalyst container. Further:

[0026] Central electrode 10: It is a conductive metal rod that is set vertically along the central axis of the sample cell and is used as a high-voltage electrode.

[0027] Quartz tube 11: A cylindrical quartz tube fitted over the outside of the central electrode 10, serving as a container for holding the catalyst 14.

[0028] Support pad 13: This is an annular pad located in the middle of the quartz tube 11. It is used to support the powdered or granular catalyst 14 and ensure that the catalyst 14 is in the infrared detection area.

[0029] Outer wall electrode 12: It is a conductive metal mesh that tightly covers the outer wall of the quartz tube 11 and is used as a grounding electrode.

[0030] With the coaxial structure described above, when the central electrode 10 and the outer wall electrode 12 are connected to an external plasma generator and a high voltage is applied, the electric field will excite dielectric barrier discharge in the catalyst 14 region inside the quartz tube 11.

[0031] The working process and operation steps of the device of the present invention are as follows:

[0032] Step 1: Device Assembly and Sample Loading. The sample cell assembly, including the central electrode 10, quartz tube 11, and outer wall electrode 12, is vertically placed in the center of the reaction cell base 2. The support pad 13 is placed at a predetermined height inside the quartz tube 11, and then the catalyst 14 to be tested is laid flat on the support pad 13. Subsequently, the conical dome 1 is covered and sealed using the fixing plate 5 and fixing bolts 4.

[0033] Step 2: Connect the pipeline and power supply. Connect the external gas supply pipeline to the gas inlet 8 and the gas outlet 9. At the same time, the gas inlet 8 and the gas outlet 9 also serve as channels for the electrode leads: connect the lead-out end of the outer wall electrode 12 through the gas inlet 8 to the power supply, and connect the lead-out end of the center electrode 10 through the gas outlet 9 to the power supply, ensuring the connection is sealed.

[0034] Step 3: In-situ Detection. The assembled in-situ reaction cell is fixed to the sample chamber of the infrared spectrometer using screw holes 6 and bolts 7. A reaction atmosphere is introduced into the sample cell through gas inlet 8, flowing downwards through the catalyst bed 14 and exiting through gas outlet 9. The plasma generator is activated to generate plasma within the catalyst 14 region. Simultaneously, the infrared spectrometer is activated, and an infrared beam enters through the entrance window 3 of the conical dome 1, is reflected by the catalyst 14 surface, exits through the exit window 3, and is received by the detector, thus achieving in-situ, real-time monitoring of the low-temperature plasma catalytic reaction process.

Claims

1. An in-situ infrared reaction apparatus for low-temperature plasma catalytic reactions, characterized in that, The device includes a reaction cell base (2) and a conical dome (1). The conical dome (1) covers the reaction cell base (2). The base (2) is machined with a gas inlet (8) and a gas outlet (9) for connecting the sample cell. The sample cell is vertically arranged in the central groove of the reaction cell base (2). The sample cell is provided with a central electrode (10), a quartz tube (11) and an outer wall electrode (12) from the inside to the outside. The quartz tube (11) is sleeved on the outside of the central electrode (10). An annular gasket (13) is provided in the middle of the central electrode (10). The area enclosed by the annular gasket (13) and the quartz tube (11) is a container for the catalyst.

2. The in-situ infrared reaction apparatus for low-temperature plasma catalytic reaction according to claim 1, characterized in that, The base (2) is also provided with sealing screw holes (6) and bolts (7) that are matched and connected to the sample chamber of the external infrared spectrometer.

3. The in-situ infrared reaction apparatus for low-temperature plasma catalytic reaction according to claim 1, characterized in that, The conical dome (1) is pressed onto the base (2) by the fixing plates (5) on both sides of the base (2), and is screwed into the pre-set conical dome fixing screw holes (15) on the base (2) by four conical dome fixing bolts (4) passing through the fixing plates (5).

4. The in-situ infrared reaction apparatus for low-temperature plasma catalytic reaction according to claim 1, characterized in that, Three windows (3) are symmetrically arranged on the conical dome (1), which are used as the entrance window, exit window and observation window for infrared light, respectively.

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