Time-resolved flash decomposition time-of-flight mass spectrometry device

Abstract

The invention belongs to the technical field of analytical chemical instruments, and particularly relates to a time-resolved flash decomposition time-of-flight mass spectrometry device. The device comprises a supporting structure, a vacuum cavity, a reaction tank assembly and a time-of-flight mass spectrum. Reactants are loaded into the flow tube reactor through a straight tube; laser emitted by an external trigger laser device is shot into the reactor from a CF63 observation window on one side, and a precursor in the reactor is photolyzed to generate free radicals which react with gas in a tube; reacted gas molecules are sampled by a sampling micropore in the center of the flow tube and a sampling nozzle, and molecular beams are introduced into a photoionization chamber and are ionized by vacuum ultraviolet light emitted by a vacuum ultraviolet discharge lamp; ionized ions are detected by time-of-flight mass spectrometry. The synchronous control module coordinates the photolysis laser and the mass spectrum sampling system, and triggers acquisition of multiple groups of mass spectrum data at preset time intervals in a single photolysis process, so that a time resolution effect is achieved, product information at different time points in single photolysis is obtained, and a powerful experimental means is provided for free radical reaction kinetics research.

Description

Technical Field

[0001] The present invention belongs to the technical field of analytical chemistry instruments, and specifically relates to a time-resolved flash decomposition time-of-flight mass spectrometer, which is particularly suitable for dynamic monitoring and high-sensitivity detection of multiple species in free radical reaction kinetics research. Background Art

[0002] Free radicals are widely present in many important chemical reaction processes, such as combustion, illumination, and chemiluminescence. They play a key catalytic role in atmospheric pollution, including urban photochemical smog, ozone depletion, and acid rain formation. The kinetics of free radical reactions involves detecting reaction rates, reaction products, and inferring reaction mechanisms. This requires effective means to simultaneously detect free radicals, intermediates, and reaction products. Many experimental techniques, such as fluorescence spectroscopy and absorption spectroscopy, are sensitive enough to detect transient species, but they can only detect small free radical reactions and are unable to detect large free radicals or multiplex detection. In principle, mass spectrometry is a universal method for the simultaneous online detection of multiple species with sufficient sensitivity and time resolution, making it a well-suited species identification method for free radical reaction kinetics studies.

[0003] Over the past few decades, numerous experiments have directly probed the kinetics of free radical reactions, using quantum chemistry combined with rate theory to predict the product branches of such reactions. Furthermore, some experimental approaches have been developed that can directly obtain quantitative information about the products and verify theoretical predictions.

[0004] Currently, the experimental methods that can directly perform time-resolved measurement of gas-phase molecular reaction rate constants mainly include: flash photolysis combined with laser-induced fluorescence; flash photolysis combined with cavity ring-down spectroscopy; flash photolysis combined with molecular beam mass spectrometry, etc.

[0005] These methods all use laser photolysis to generate target free radicals from specific precursor molecules, induce reactions, and then select specific molecular excitation or absorption wavelengths to track the changes in the concentration of a specific product over time. Mass spectrometry is more versatile than spectroscopy, but conventional electron ionization, due to its high energy, produces a large amount of fragmentation, making product identification and tracking very difficult.

[0006] Therefore, in order to achieve comprehensive time-resolved detection of free radical reaction products and explore the kinetics of free radical reactions more quickly, we urgently need a comprehensive detection device that can achieve high time resolution, low fragment interference and precise environmental control. Summary of the Invention

[0007] The purpose of the present invention is to provide a time-resolved flash decomposition time-of-flight mass spectrometer, which realizes efficient sampling of multiple time points during a single photolysis process through a vacuum gradient environment, an adjustable reaction cell component and a synchronous control system, while reducing fragment interference and secondary reactions.

[0008] To achieve the above objectives, the present invention provides the following technical solutions:

[0009] The present invention provides a time-resolved flash decomposition time-of-flight mass spectrometry device, comprising:

[0010] A support structure that can adjust the height and level of the device;

[0011] A vacuum chamber comprising a beam source chamber and an ionization chamber, wherein the beam source chamber and the ionization chamber form a vacuum gradient environment through a connection structure;

[0012] A reaction cell assembly is provided in the beam source chamber, comprising a flow tube reactor, an adjustable connecting component and a sampling device, wherein the adjustable connecting component is used to adjust the relative position of the flow tube reactor and the sampling device;

[0013] a photoionization detection module, connected to the ionization chamber, for ionizing molecules and detecting ions;

[0014] The synchronization control module is used to coordinate the photolysis laser and the mass spectrometry sampling system to trigger the acquisition of multiple sets of mass spectrometry data at preset time intervals during a single photolysis process.

[0015] Preferably, the vacuum gradient environment is achieved by differential pumping, and the beam source chamber is connected to a molecular pump to maintain a vacuum degree lower than 1×10 -3 Pa, the ionization chamber is connected to a molecular pump to maintain a vacuum higher than 1×10 -5 Pa.

[0016] Preferably, the support assembly includes a fixing frame, a support adjuster and casters, the support adjuster is connected to the fixing frame and the laboratory table panel, and the casters are fixed to the fixing frame through angle brackets.

[0017] Preferably, the adjustable connection component includes a bellows and a three-dimensional adjustment platform, the flow tube reactor is connected to the vacuum chamber through the bellows, and the three-dimensional adjustment platform is used to adjust the distance between the sampling micropore and the sampling nozzle to 1-2 mm.

[0018] Preferably, the sampling device comprises a funnel-shaped sampling nozzle made of metal, with a 200-micron hole at the tip, and the sampling nozzle is located at the center of the ionization chamber.

[0019] Preferably, the photoionization detection module comprises a vacuum ultraviolet discharge lamp and a time-of-flight mass spectrometer, wherein the vacuum ultraviolet discharge lamp emits vacuum ultraviolet light to ionize molecules;

[0020] The time-of-flight mass spectrometer has a resolution of 800 and a sensitivity of 6 ppm.

[0021] Preferably, the preset time interval of the synchronization control module is 50 μs, and the photolysis laser triggers the photolysis of the precursor at a wavelength of 248 nm.

[0022] Preferably, the reaction cell assembly further comprises a heating wire and a thermocouple, and the heating wire and the thermocouple are wound around the surface of the flow tube reactor to control the reaction temperature.

[0023] Preferably, the beam source chamber of the vacuum cavity is formed by a pair of tees symmetrically welded to the two ends of a four-way straight tube, the left and right outlets of the tees are connected to water-cooling flanges, and a CF63 observation window is provided on the outside of the water-cooling flange.

[0024] Preferably, a straight pipe No. 1 is fixed between the outer side of the water-cooling flange and the CF63 observation window;

[0025] A 6mm pipe is welded to the side of a No. 1 straight pipe for introducing experimental reactants;

[0026] Two KF40 interfaces are welded on the side of the other straight pipe. One KF40 interface is connected to a vacuum gauge, and the other KF40 interface is connected to a multi-stage Roots pump through a butterfly valve. The vacuum gauge is linked to the controller to adjust the pressure of the reaction tank.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention achieves flash photolysis in a low-pressure environment through a novel vacuum cavity design, and combined with time-resolved photoionization mass spectrometry technology, it can avoid secondary reactions while maintaining the thermochemical environment, thereby obtaining a purer research system, which is crucial for the study of free radical reaction kinetics.

[0029] Secondly, the reaction cell assembly in the present invention can provide the required thermochemical environment, and through the precise adjustment of the sampling micropores and the sampling nozzle, quasi-in-situ sampling is achieved, thereby improving the sampling efficiency and signal intensity, and thus enhancing the sensitivity and resolution of mass spectrometry detection.

[0030] In addition, the present invention is also equipped with a synchronous control module, which can collect multiple sets of mass spectrometry data during a single photolysis process, realize time-resolved detection, and intuitively obtain information on reactants and products at different time points of a single photolysis, which provides great convenience for studying reaction rate and reaction mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the overall structure of the mass spectrometer of the present invention;

[0032] Figure 2 This is a schematic diagram of the support structure of the present invention;

[0033] Figure 3 This is a schematic diagram of the front structure of the vacuum chamber of the present invention;

[0034] Figure 4 for Figure 3 AA cross-sectional view;

[0035] Figure 5 This is a schematic diagram of the back structure of the vacuum chamber of the present invention;

[0036] Figure 6 This is a schematic diagram of the top view of the vacuum chamber structure of the present invention;

[0037] Figure 7 for Figure 6 AA section view;

[0038] Figure 8 for Figure 7 The partial enlarged view at point D in the middle shows the relative position relationship between the sampling microhole and the sampling nozzle;

[0039] Figure 9 This is a schematic diagram of the overall assembly structure of the flow tube reactor of the present invention;

[0040] Figure 10 (a) is the mass spectrometry signal of •CH2I radical measured in the experimental example;

[0041] Figure 10 (b) is the photoionization efficiency curve of the 46-channel mass-to-charge ratio measured in the experimental example;

[0042] In the figure: 1. Fixing frame; 12. Casters; 13. Laboratory table panel; 131. Optical platform panel; 15. Support adjuster; 2. Tee pipe; 21. Support vertical plate; 22. ISO200 vacuum blind flange; 23. Electrode flange; 25. CF200 water cooling flange; 251. No. 1 straight pipe; 253. Connecting pipe; 254. CF63 observation window; 26. Vacuum gauge; 3. Four-way tubular straight pipe; 31. Time-of-flight mass spectrometer; 32. Three-dimensional platform; 33. Photodiode; 34. Molecular pump; 36. Vacuum ultraviolet discharge lamp; 37. Upper straight pipe; 38. Lower straight pipe; 41. Bellows; 42. Flow tube reactor; 421. CF35 adjustment rod; 422. Sampling nozzle; 423. Sampling micropore; 424. Flange fixing plate; 425. Flange pressure ring. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0044] like Figure 1As shown, the time-resolved flash decomposition time-of-flight mass spectrometer provided by the present invention consists of five core modules: a support structure, a vacuum chamber, a reaction cell assembly, a photoionization detection module, and a synchronization control module. These modules work together to achieve high-time-resolution dynamic monitoring of free radical reactions.

[0045] The support structure includes a fixing frame 1, a support adjuster 15, casters 12 and a laboratory table panel 13. Figure 2 As shown, the fixing frame 1 as a whole can be a rectangular frame structure, and polyurethane casters 12 with built-in brake devices are installed at the four corners of the lower end through corner brackets; the upper end of the fixing frame 1 is installed with a laboratory table panel 13 through multiple support adjusters 15, wherein the support adjuster 15 can be a spiral elevator or other types of one-dimensional height adjusters, as long as the horizontal and height adjustments of the laboratory table panel 13 can be achieved. The base and the lead screw nut of the spiral elevator are hinged to the fixing frame 1 and the laboratory table panel 13 respectively, and the horizontal adjustment of the laboratory table panel 13 can be achieved by adjusting the height of the spiral elevators arranged in multiple directions. In addition, in order to facilitate the installation of optical elements such as laser reflectors, lens groups and optical path adjustment brackets, an optical platform panel 131 can be fixedly installed on the right side of the upper surface of the laboratory table panel 13, and the array of threaded holes on it can realize the rapid installation of optical elements.

[0046] like Figure 3-Figure 5 As shown, the vacuum chamber includes a beam source chamber and an ionization chamber, which are connected by a four-way straight tube 3 to form a vacuum gradient environment. The beam source chamber comprises a pair of tees 2 and a four-way straight tube 3. The two tees 2 are symmetrically welded to the left and right ends of the four-way straight tube 3, forming a cylindrical beam source chamber. The entire beam source chamber is fixed to the experimental table panel 13 by a pair of support plates 21.

[0047] The front outlet of the tee 2 uses an ISO200 flange interface and is sealed by a pair of ISO200 vacuum blind flanges 22. The outlets on both ends of the tee 2 use CF200 flange interfaces and are connected and sealed by external CF200 water-cooling flanges 25. The CF200 water-cooling flanges 25 have built-in circulating cooling water channels with a cooling water flow rate of 2L / min, which can ensure the sealing of the CF200 water-cooling flanges 25 during high-temperature experiments.

[0048] The outer side of the CF200 water-cooling flange 25 is connected to the No. 1 straight pipe 251, and the end of the No. 1 straight pipe 251 is sealed and connected to the CF63 observation window 254 through the CF63 vacuum flange interface. The transmittance of the quartz window is greater than 90%, and the laser can be incident into the flow tube reactor 42 through this window.

[0049] The upper straight tube 37 of the four-way tubular straight tube 3 constitutes an ionization chamber, and one side of the upper straight tube 37 is connected to an external molecular pump 34 through a branch pipe, and the lower straight tube 38 is directly connected to an external molecular pump 34. Thus, the vacuum degree of the beam source chamber is maintained below 1×10 -3 Pa, the vacuum degree of the ionization chamber is higher than 1×10 -5 In addition, to achieve real-time monitoring of the vacuum maintenance status of each area of the device, a vacuum gauge 26 can be installed on the No. 1 straight pipe 251 connected to the outside of the right CF200 water-cooling flange 25 and on the upper end straight pipe 37 of the right three-way pipe 2 and the four-way tubular straight pipe 3 through a KF40 interface.

[0050] like Figure 8 As shown, a sampling nozzle 422 is fixedly mounted within the ionization chamber. Because the vacuum level in the ionization chamber is typically higher than that in the beam source chamber, sampling nozzle 422 can be designed as a funnel-shaped metal material, preferably tantalum alloy. A 200-micron aperture is provided at the tip of sampling nozzle 422, enabling differential sampling while simultaneously sampling from the beam source chamber to form an ultrasonic molecular beam, achieving quasi-in-situ sampling.

[0051] The sampling nozzle 422 is installed at the central axis of the ionization chamber. Specifically, it can be installed in the upper straight tube 37 of the four-way tubular straight tube 3 through the flange fixing plate 424, and the vacuum seal is ensured by the flange pressure ring 425.

[0052] like Figure 4 As shown, a vacuum ultraviolet discharge lamp 36 and a photodiode 33 are fixedly mounted on the side of the ionization chamber via a pair of opposing flange interfaces. The vacuum ultraviolet discharge lamp 36 emits vacuum ultraviolet light to ionize molecules entering the ionization chamber into ions. The ions enter the external time-of-flight mass spectrometer 31 above the ionization chamber and are detected. The photodiode 33, mounted directly opposite the vacuum ultraviolet discharge lamp 36, can be used to monitor the light flux signal in real time.

[0053] like Figure 4 、 Figure 7-Figure 9 As shown, the reaction cell assembly may specifically include a flow tube reactor 42, a bellows 41, a CF35 adjustment rod 421, and a sampling micropore 423. The flow tube reactor 42 may be a 316L stainless steel tube with an inner diameter of 60 mm and a wall thickness of 2 mm, with a nickel-chromium heating wire and a K-type thermocouple wrapped around the surface. The heating wire is fixed by a ceramic insulating sleeve, and the thermocouple signal line is led out to an external temperature controller through the electrode flange 23 to meet the thermochemical environment required for the reaction. The two ends of the flow tube reactor 42 are respectively fixedly connected to the bellows 41, and then the flexible characteristics of the bellows 41 are used to make the spatial position of the flow tube reactor 42 in the beam source chamber easy to adjust.

[0054] like Figure 7As shown, one end of the bellows 41 away from the flow tube reactor 42 is connected to the inner side of the CF200 water-cooling flange 25 through the CF63 flange, and is connected to the No. 1 straight pipe 251.

[0055] like Figure 4 As shown, the middle portion of the flow tube reactor 42, near its lower portion, is fixedly connected to one end of a CF35 adjustment rod 421. The other end of the CF35 adjustment rod 421 is connected to a small three-dimensional platform 32. This three-dimensional platform 32 can be an XYZ three-dimensional translation stage model XYZ70-70-S manufactured by Dalian Qiwei Technology Development Co., Ltd. The upper portion of the middle portion of the flow tube reactor 42 is designed as a concave surface with a sampling microhole 423 defined in the center. The spatial position of the sampling microhole 423 can be adjusted by the CF35 adjustment rod 421 and the small three-dimensional platform 32 to a position that coincides with the horizontal projection of the sampling nozzle 422. The height of the sampling microhole 423 and the sampling nozzle 422 is 1-2 mm apart. This allows molecules within the beam source chamber to be more easily drawn into the ionization chamber by the sampling nozzle 422 under the action of the vacuum pressure difference, thereby improving sampling efficiency and ensuring that sufficient molecules enter the ionization chamber for subsequent ionization and detection.

[0056] like Figure 3 As shown, a 6mm pipe 253 is welded to the side of the left straight pipe 251 for introducing experimental reactants. Two KF40 ports are welded to the side of the right straight pipe 251. One KF40 port is connected to a vacuum gauge 26, and the other is connected to a multi-stage Roots pump via a butterfly valve. During experiments, the vacuum level feedback from the vacuum gauge 26 is read in real time to control the butterfly valve opening, ensuring that the reaction cell pressure remains within the appropriate range.

[0057] The synchronization control module specifically includes a Stanford DG535 pulse delay generator and a software control interface. The output channel of the Stanford DG535 pulse delay generator synchronously controls the laser and mass spectrometer trigger signals.

[0058] The specific control logic is as follows: a Stanford DG535 pulse delay generator generates a laser trigger signal and sends it to the Nd:YAG laser. After receiving the signal, the Nd:YAG laser delays 50 ns to emit a photolysis pulse. The mass spectrometer trigger signal is sent to the time-of-flight mass spectrometer 31 with a delay of Δt after the laser trigger to start data acquisition. Δt is adjustable and defaults to 50 μs. Within a single photolysis cycle, the pulse generator continuously sends 20 sets of trigger signals at a preset time interval of 50 μs to collect mass spectrometry data at multiple time points.

[0059] Furthermore, LabVIEW can be used to develop specialized control software, integrating vacuum monitoring, temperature control, laser parameter settings, and data acquisition modules. Vacuum gauge and thermocouple signals can be transmitted to the control software in real time via a DAQ module to automatically adjust the butterfly valve opening and heating power.

[0060] Experimental Example: Kinetic Study on the Generation of CH2I Radicals by Photolysis of CH2I2

[0061] 1. Experimental Preparation:

[0062] Reactants: iodomethane (CH2I2, concentration 0.1%), helium (purity 99.999%);

[0063] Carrier gas flow rate: helium flow rate 50 mL / min, CH2I2 vapor partial pressure 0.1 Pa, total pressure 1.5 kPa;

[0064] Laser parameters: Nd:YAG laser (wavelength 248 nm, pulse energy 50 mJ, repetition rate 10 Hz).

[0065] 2. Experimental steps:

[0066] ① A mixed gas of helium and iodomethane is introduced into the flow tube reactor 42 through a 6 mm pipe 253 welded to the side of the left straight pipe 251;

[0067] ② Start the molecular pumps 34 connected to the beam source chamber and ionization chamber respectively, and stabilize the vacuum degree of the beam source chamber to 5×10 -3 Pa, the vacuum degree of the ionization chamber is stable to 2×10 -5 Pa;

[0068] ③ Adjust the three-dimensional platform 32 so that the sampling micropore 423 and the sampling nozzle 422 overlap in horizontal projection, with a spacing of 1.5 mm;

[0069] ④ Set up the synchronization control module: the time interval is 50 μs, and 20 sets of data are collected in a single photolysis cycle;

[0070] ⑤ Start the laser and time-of-flight mass spectrometer 31 and start data collection.

[0071] 3. Experimental results:

[0072] like Figure 10 As shown in Figure a, the mass spectrometry signal of the •CH2I radical was clearly measured in the experiment. After the introduction of O2, the generation of CH2OO was detected, confirming the reaction pathway of •CH2I and O2.

[0073] The overall mass spectrometry resolution is M / ΔM = 800, the sensitivity reaches 6 ppm, and the time resolution reaches 50 μs.

[0074] like Figure 10 As shown in b, by scanning the energy of vacuum ultraviolet light, the photoionization efficiency curves of 46 channels of mass-to-charge ratio can be obtained simultaneously, realizing accurate identification of the product.

[0075] From the above experimental examples, it can be found that the 50μs time resolution of the present invention combined with the mass spectrometry performance of 800 can detect transient species as low as 6ppm; at the same time, the vacuum gradient (beam source chamber <1×10 -3 Pa, ionization chamber>1×10 -5 The synergistic effect of the temperature control system (±2°C) and the temperature control system (±2°C) can effectively suppress side reactions, thereby intuitively and clearly obtaining information on reactants and products at different time points in a single photolysis, greatly facilitating the study of reaction rate and reaction mechanism.

[0076] It should be noted that the above description is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A time-resolved flash decomposition time-of-flight mass spectrometer, characterized in that: include: A support structure that can adjust the height and level of the device; A vacuum chamber comprising a beam source chamber and an ionization chamber, wherein the beam source chamber and the ionization chamber form a vacuum gradient environment through a connection structure; A reaction pool assembly is provided in the beam source chamber, comprising a flow tube reactor (42), an adjustable connecting component and a sampling device, wherein the adjustable connecting component is used to adjust the relative position of the flow tube reactor (42) and the sampling device; a photoionization detection module, connected to the ionization chamber, for ionizing molecules and detecting ions; The synchronization control module is used to coordinate the photolysis laser and the mass spectrometry sampling system to trigger the acquisition of multiple sets of mass spectrometry data at preset time intervals during a single photolysis process.

2. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The vacuum gradient environment is achieved by differential pumping, and the beam source chamber is connected to a molecular pump (34) to maintain a vacuum degree lower than 1×10 -3 Pa, the ionization chamber is connected to a molecular pump (34) to maintain a vacuum higher than 1×10 -5 Pa.

3. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The support structure comprises a fixing frame (1), a support adjuster (15) and a caster (12), wherein the support adjuster (15) connects the fixing frame (1) and the laboratory table panel (13), and the caster (12) is fixed to the fixing frame (1) via an angle bracket.

4. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The adjustable connection component includes a bellows (41) and a three-dimensional platform (32). The flow tube reactor (42) is connected to the vacuum chamber via the bellows (41). The three-dimensional platform (32) is used to adjust the distance between the sampling micropore (423) and the sampling nozzle (422) to 1-2 mm.

5. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The sampling device comprises a funnel-shaped sampling nozzle (422) made of metal, a 200-micron hole being opened at the tip thereof, and the sampling nozzle (422) is located at the center of the ionization chamber.

6. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The photoionization detection module includes a vacuum ultraviolet discharge lamp (36) and a time-of-flight mass spectrometer (31), wherein the vacuum ultraviolet discharge lamp (36) emits vacuum ultraviolet light to ionize molecules; The time-of-flight mass spectrometer (31) had a resolution of 800 and a sensitivity of 6 ppm.

7. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The preset time interval of the synchronization control module is 50 μs, and the photolysis laser triggers the photolysis of the precursor at a wavelength of 248 nm.

8. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The reaction pool assembly also includes a heating wire and a thermocouple, and the heating wire and the thermocouple are wound around the surface of the flow tube reactor (42) to control the reaction temperature.

9. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 1, characterized in that: The beam source chamber of the vacuum cavity is formed by a pair of three-way pipes (2) symmetrically welded to the two ends of a four-way tubular straight pipe (3), and the left and right outlets of the three-way pipe (2) are connected to water-cooling flanges, and a CF63 observation window (254) is provided on the outside of the water-cooling flange.

10. The time-resolved flash decomposition time-of-flight mass spectrometer according to claim 9, characterized in that: A straight pipe (251) is fixed between the outer side of the water-cooling flange and the CF63 observation window (254); A 6 mm pipe (253) is welded to the side of a No. 1 straight pipe (251) for introducing experimental reactants; Two sections of KF40 interfaces are welded to the side of another No. 1 straight pipe (251), one of the KF40 interfaces is connected to a vacuum gauge (26), and the other KF40 interface is connected to a multi-stage Roots pump through a butterfly valve. The vacuum gauge (26) is linked to the controller to adjust the pressure of the reaction tank.

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