A catalytic reaction system and in-situ catalytic reaction method capable of realizing multi-point sampling

Abstract

The application discloses a catalytic reaction system capable of realizing multi-point sampling and an in-situ catalytic reaction method, and belongs to the technical field of chemical equipment. The catalytic reaction system comprises a supporting frame, a tubular reactor fixed on the supporting frame, and a heating device for heating the tubular reactor; the tubular reactor comprises an outer tube, an inner tube coaxially nested in the outer tube, and a plurality of sampling holes are axially arranged on the inner tube in a region where a catalyst bed is arranged; a nozzle is connected to the middle part of the outer tube, and the nozzle is connected with a synchrotron radiation photoionization mass spectrometry system through a nickel strainer. The in-situ catalytic reaction method using the catalytic reaction system can realize high-precision, high-time-space-resolution, multi-component synchronous sampling and analysis under in-situ catalytic reaction conditions, significantly improves the integrity, reliability and repeatability of sample collection, and is suitable for catalytic mechanism research and reaction kinetics analysis.

Description

Technical Field

[0001] This invention belongs to the field of chemical equipment technology, specifically relating to a catalytic reaction system and an in-situ catalytic reaction method capable of multi-point sampling. Background Technology

[0002] In-situ catalytic reaction research is one of the important directions in modern catalysis science. Its core objective is to obtain real-time information on the dynamic changes of reactants, intermediates, and products under reaction conditions, thereby revealing reaction mechanisms, determining the properties of active sites, and guiding catalyst optimization. In recent years, with the in-depth development of high-temperature catalytic reactions, combustion reactions, and environmental catalysis, the demand for in-situ detection methods with high spatiotemporal resolution has been increasing.

[0003] In current technologies, sampling devices are crucial for connecting the reaction system and the analytical detection system in in-situ reaction studies. Traditional reactors mostly employ single-point sampling or end-of-reaction emission detection, only providing overall reaction results and failing to reflect the spatial distribution characteristics of the reaction along the process. This is especially true in gas-solid phase catalytic reactions (such as methane oxygen-free aromatization, methanol-to-hydrogen, and CO2 hydrogenation), where reactant concentrations, free radical types, and intermediate concentrations vary significantly with catalyst stacking and temperature gradients, making single-point sampling ineffective in revealing these differences. With advancements in analytical techniques, synchrotron radiation photoionization mass spectrometry (SR-PIMS), due to its high sensitivity and soft ionization characteristics, has become a powerful tool for studying free radicals and intermediates in gas-phase and surface reactions. However, most publicly available reactors, both domestically and internationally, employ single-point sampling structures. When coupled with synchrotron radiation mass spectrometry, the time delay between sampling and transmission in the reaction zone remains relatively long, hindering instantaneous and multi-point in-situ sampling of the reaction process. Therefore, there is an urgent need for a device that can maintain airtightness and undisturbed operation at high temperatures, enabling multi-point synchronous sampling and direct coupling with analytical systems such as SR-PIMS.

[0004] In the prior art, the Chinese patent (CN202110269146.6) for a multi-point online sampling device for high-temperature fluidized bed reactors mainly consists of a sampling module and a lifting control module. An annular sampling chamber is formed by the shell and the through-feed sampling tube, and particle samples are collected and cooled for preservation through heat exchange components, a gas-solid separation unit, and a cooling system. This device is suitable for particle sampling under normal or pressurized conditions, can achieve multi-point sampling at different heights, is relatively simple to operate, and has wide applicability. However, this device is mainly designed for particle sampling, and its sampling accuracy is limited, making it difficult to meet the requirements for rapid capture and online analysis of trace gaseous or liquid products and active intermediates in in-situ catalytic reactions. Furthermore, the accuracy of sampling position adjustment and the sample cooling response speed are somewhat limited, failing to fully guarantee the integrity and repeatability of samples under in-situ chemical reaction conditions.

[0005] Existing online sampling devices for high-temperature reactors mainly include single-point sampling fixed-bed reactors, multi-channel split sampling systems (CN2016103090460), and in-situ infrared or Raman spectroscopy analysis systems. Although these technologies have made some progress in single-point detection, online analysis, and spectroscopic coupling, they still have the following drawbacks:

[0006] 1. Insufficient multi-point synchronous sampling capability: Single-point and moving probe systems cannot acquire reactant or intermediate samples from different locations at the same time. Multi-point sampling is intermittent and the response speed is slow, making it difficult to meet the requirements of high spatiotemporal resolution for in-situ reaction mechanism research.

[0007] 2. Limited sampling accuracy and sample integrity: Due to flow resistance and temperature differences, multi-channel split systems cannot guarantee consistent sampling volume across all sampling channels; traditional cooling and collection methods may lead to degradation or loss of active intermediates in high-temperature environments.

[0008] 3. Insufficient high temperature tolerance and system compatibility: Existing devices have limited sealing and high temperature resistance in high-temperature reaction environments above 700℃, and cannot be efficiently coupled with high-sensitivity analytical systems such as synchrotron radiation photoionization mass spectrometry. Summary of the Invention

[0009] Existing technologies for in-situ catalytic reaction research generally employ single-point or endpoint sampling methods, which cannot achieve multi-location, time-resolved component detection during the reaction process. This leads to problems such as difficulty in obtaining the distribution of reactants, intermediates, and products along the process, thus limiting in-depth research on reaction mechanisms and kinetic processes. The purpose of this invention is to provide a catalytic reaction system and in-situ catalytic reaction method that can achieve multi-point sampling, so as to realize in-situ real-time monitoring and analysis of catalytic reactions.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A catalytic reaction system capable of multi-point sampling includes: a support frame, a tubular reactor fixed on the support frame, and a heating device for heating the tubular reactor.

[0012] The tubular reactor includes an outer tube and an inner tube coaxially nested inside the outer tube; both ends of the inner tube extend out of the outer tube; both ends of the outer tube are movably connected to the inner tube via a sealing mechanism.

[0013] The inner tube has multiple sampling holes along the axial direction in the area where the catalyst bed is arranged. The sampling holes cover the inlet, middle section and outlet areas of the catalyst bed. The specific number and spacing of the sampling holes can be set according to experimental needs. They are used to obtain the composition of gaseous products representing different reaction stages. During the catalytic reaction, by controlling the axial displacement of the inner tube relative to the outer tube, the sampling holes at different positions on the inner tube are sequentially directed toward the opening of the outer tube and then connected to the sampling port. This enables the intermediates and products located along the catalyst bed in the inner tube to be discharged from the nozzle and detected in real time, thus achieving multi-point sampling and obtaining spatial distribution information of the reaction path.

[0014] The outer tube has an opening in the middle, and a nozzle is connected to the opening. The tip of the nozzle has a sampling port that communicates with the inner cavity of the outer tube. The nozzle is connected to the synchrotron radiation photoionization mass spectrometry system via a nickel-plated strainer. The cavity formed between the nozzle and the nickel-plated strainer is a differential pumping chamber. The main function of the nozzle is to limit the flow through the sampling port via a micro-orifice, controlling the gas flux entering the differential pumping chamber, thereby maintaining the ionization chamber at a suitable operating pressure. The main function of the differential pumping chamber is to establish a pressure gradient between the high-pressure sampling zone of the nozzle and the ultra-high vacuum zone of the ionization chamber, reducing the gas flow rate through stepwise pumping, ensuring that the ionization chamber maintains a stable low-pressure environment, and improving the sensitivity and stability of the detection.

[0015] One end of the inner tube is connected to a reaction raw material gas supply pipeline; preferably, the reaction raw material gas supply pipeline includes a carrier gas pipeline and a reaction gas pipeline, which are connected to one end of the inner tube through a first tee connector; the other end of the inner tube is connected to a second tee connector, and the other two connectors of the second tee connector are respectively connected to a needle valve and a vacuum gauge, the vacuum level is observed by the vacuum gauge, and the pipeline tightness is checked by the needle valve.

[0016] As a preferred technical solution, the nozzle is connected to a nickel-plated strainer via a flange; the flange is fixedly connected to a support frame; a connecting plate is provided between the nozzle and the flange; the nozzle, connecting plate, and flange are sealed together; a connector is connected to one side of the bottom of the support frame, and the connecting plate is fixedly connected to the support frame via the connector. The flange is thus fixed by the support frame's fixing action on the support plate. Specifically, the connector can use a screw hole and bolt connection to fix the connecting plate to the support frame.

[0017] As a preferred technical solution, the sealing mechanism includes a connector fixedly sleeved on the outside of the outer tube, the connector being sealed to the outer tube; the two ends of the connector are a first threaded end and a second threaded end; the first threaded end is connected to the inner tube via a first sealing assembly; the second threaded end is connected to the inner tube via a second sealing assembly; the first sealing assembly includes a first sealing gasket and a first pressure ring sleeved on the outside of the inner tube, and a first nut threadedly connected to the first threaded end; the first sealing gasket and the first pressure ring are located between the first threaded end and the inner tube; when the first nut is tightened to the first threaded end, the first pressure ring presses against the outer surface of the inner tube, providing a seal without completely preventing axial sliding of the inner tube; furthermore, the sealing gasket further ensures the sealing performance between the inner and outer tubes; the second sealing assembly includes a second sealing gasket and a second pressure ring sleeved on the outside of the inner tube, and a second nut threadedly connected to the second threaded end. The function of the second sealing assembly is the same as that of the first sealing assembly.

[0018] As a preferred technical solution, the opening of the outer tube extends outward perpendicularly to the outer tube to form a support tube, and the nozzle is connected to the outer tube through the support tube; the nozzle is funnel-shaped; the tip of the nozzle is a sampling port; the diameter of the sampling port is in the range of 350–75 μm, and the gas pressure entering the differential pumping chamber is adjusted by controlling the nozzle diameter.

[0019] As a preferred technical solution, the heating device includes a heating jacket and a housing for fixing the heating jacket. The heating jacket includes a lower base and an upper base with identical structures and symmetrical arrangement. A T-shaped groove is formed on the top of the lower base, comprising a horizontal groove for accommodating an outer tube and a vertical groove for accommodating a nozzle. A through-hole is formed at the bottom of the T-shaped groove, penetrating the lower base, for arranging a temperature monitoring element. Heating wires are installed on the sidewalls of the horizontal groove to achieve directional heating of the reaction tube area. The housing covers the exterior of the heating jacket and is fixed to the top of the support frame. More preferably, the heating jacket is made of mullite ceramic fiber material. It possesses high temperature resistance, low thermal conductivity, and excellent heat insulation performance, maintaining a stable temperature field of 1000 ℃ in a compact volume. A thermocouple is installed in the through-hole to achieve real-time monitoring of the reaction temperature. While meeting the small-size requirements of in-situ multi-point sampling reactors, the heating jacket provides a more uniform temperature distribution and higher temperature control accuracy, reduces temperature differences along the process, and provides a stable and reliable thermal environment for reaction mechanism research.

[0020] This invention also provides an in-situ catalytic reaction method capable of multi-point sampling, which utilizes the catalytic reaction system described above and includes the following steps:

[0021] The tubular reactor is heated using a heating device to bring the temperature to the catalytic reaction temperature.

[0022] The reactant gas is delivered to the inner tube through the reactant gas supply pipeline for reaction.

[0023] Based on the fact that the inner tube has multiple sampling holes along the axial direction in the area where the catalyst bed is arranged, by distributing the sampling holes to cover the inlet, middle and outlet areas of the catalyst bed, during the catalytic reaction, by controlling the axial displacement of the inner tube relative to the outer tube, the sampling holes at different positions on the inner tube are sequentially directed toward the opening of the outer tube. Since the opening is connected to the sampling port, the reactants at different positions can enter the nozzle from the sampling port, and finally enter the detection device through the nickel sieve and be detected in real time, thereby obtaining the spatial distribution information of the reaction path.

[0024] The present invention has the following beneficial effects:

[0025] The catalytic reaction system provided by this invention can rapidly capture gaseous and trace amounts of reaction intermediates, avoiding sample degradation or loss. It is designed with an interface compatible with online analysis equipment, enabling in-situ real-time monitoring and analysis. Compared with existing technologies, this invention can achieve high-precision, high spatiotemporal resolution, and simultaneous sampling and analysis of multiple components under in-situ catalytic reaction conditions, significantly improving the integrity, reliability, and repeatability of sample collection. It is suitable for catalytic mechanism research and reaction kinetic analysis.

[0026] The main function of the nozzle in the reactor provided by this invention is to limit the flow through micro-orifices. By controlling the diameter of the sampling port on the nozzle, the gas flux entering the differential extraction chamber is controlled, allowing the ionization chamber to maintain a suitable operating pressure. This design enables the reaction system to maintain a stable main gas flow while meeting the requirements of low-pressure in-situ detection, thereby more accurately reflecting the spatial distribution and concentration changes of intermediates and free radicals during the reaction process, significantly improving the spatiotemporal resolution and detection sensitivity of the device.

[0027] This invention offers versatility and applicability across multiple fields. The device can be used not only in high-temperature catalytic systems such as methane anaerobic aromatization, methanol-to-hydrogenation, and CO2 hydrogenation, but also in online monitoring of combustion reactions, exhaust gas purification, bio-fermentation, and environmental processes, demonstrating broad prospects for scientific research and engineering applications. Attached Figure Description

[0028] Figure 1 A simplified structural diagram of the catalytic reaction system provided by this invention;

[0029] Figure 2 for Figure 1 A schematic diagram of the connection between the inner and outer tubes and the nozzle;

[0030] Figure 3 A schematic diagram of the assembly structure of the support frame, tubular reactor, and heating device;

[0031] Figure 4 for Figure 3 Exploded view;

[0032] Figure 5 A schematic diagram of the connection structure between the tubular reactor and the nozzle;

[0033] Figure 6 for Figure 5 Exploded view;

[0034] Figure 7 This is an exploded view of the heating device;

[0035] Figure 8 The catalytic reaction system provided by this invention is applied to the MDA reaction, and the test results are shown at the beginning and end of the reaction after 5 minutes of reaction.

[0036] Figure 9 The catalytic reaction system provided by this invention is applied to the MDA reaction, and the test results are shown at the beginning and end of the reaction after 30 min of reaction.

[0037] Reference numerals: 1-Tubular reactor, 101-Outer tube, 102-Inner tube, 103-Sampling port, 104-Opening, 2-Nozzle, 3-Support tube, 4-Sampling port, 5-Heating device, 50-Heating jacket, 51-Lower base, 52-Upper base, 53-Horizontal groove, 54-Vertical groove, 55-Heating wire, 56-Thermocouple, 57-Shell, 6-Support frame, 7-Nickel strainer, 8-Differential extraction chamber, 9-Flange, 10-Connecting plate 11-Connector, 12-Carrier gas pipeline, 13-Sealing mechanism, 131-Connector, 132-First threaded end, 133-Second threaded end, 134-First sealing gasket, 135-First pressure ring, 136-First nut, 137-Second sealing gasket, 138-Second pressure ring, 139-Second nut, 14-Reaction gas pipeline, 15-First tee connector, 16-Second tee connector, 17-Needle valve, 18-Vacuum gauge. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention. In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail.

[0039] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations of the invention. The terms "first" and "second" used in this invention do not represent a specific quantity or order, but are merely used for distinguishing names.

[0040] It should be noted that in this invention, terms such as "connection" and "installation" indicate that two interconnected components are fixed together, typically by welding, screws, or adhesive. For example, this can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to internal communication between two components. "Movable installation" means that two components are connected together and can move relative to each other. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0041] In gas-solid phase catalytic reactions, sampling points are typically located at the end of the gas flow (such as in fixed-bed or fluidized-bed reactors). Detection results mostly reflect the final product, making it difficult to detect reactive intermediates during the reaction process, or only capturing trace signals. Consequently, it is impossible to accurately reveal the spatial distribution of intermediates and the reaction mechanism. This limitation leads to a lack of real-time data for catalyst structure design and performance regulation, hindering further improvements in catalytic efficiency.

[0042] The catalytic reaction system provided by this invention can simultaneously acquire real-time signals from multiple locations during the same reaction process, achieving spatially resolved detection along the reaction path. By adjusting the relative positions of the inner and outer tubes, rapid multi-point sampling can be achieved, effectively avoiding disturbances to the flow field and temperature distribution caused by probe movement, and ensuring the authenticity and repeatability of in-situ test results.

[0043] Example 1

[0044] refer to Figures 1 to 7 A catalytic reaction system capable of multi-point sampling includes: a support frame 6, a tubular reactor 1 fixed on the support frame 6, and a heating device 5 for heating the tubular reactor 1; wherein:

[0045] The tubular reactor 1 includes an outer tube 101 and an inner tube 102 coaxially nested within the outer tube. Both ends of the inner tube 102 extend out of the outer tube 101. Both ends of the outer tube 101 are movably connected to the inner tube 102 via a sealing mechanism 13. The sealing mechanism 13 includes a connector 131 fixedly sleeved on the outside of the outer tube 101, which is sealed to the outer tube 101. The connector 131 has two ends: a first threaded end 132 and a second threaded end 133. The first threaded end 132 is connected to the inner tube 102 via a first sealing assembly; the second threaded end 133 is connected to the inner tube 102 via a second sealing assembly. The first sealing assembly includes a... The first sealing gasket 134 and the first pressure ring 135, and the first nut 136 threadedly connected to the first threaded end 132; the first sealing gasket 134 and the first pressure ring 135 are located between the first threaded end 132 and the inner tube 102; when the first nut 136 is tightened with the first threaded end 132, the first pressure ring 135 is pressed against the outer surface of the inner tube 102, which can seal the tube but does not completely prevent the axial sliding of the inner tube 102; the second sealing assembly includes a second sealing gasket 137 and a second pressure ring 138 sleeved on the inner tube 102, and a second nut 139 threadedly connected to the second threaded end 133, and the function of the second sealing assembly is the same as that of the first sealing assembly.

[0046] The outer tube 101 has an opening 104 in the middle, and a nozzle 2 is connected to the opening 104. The tip of the nozzle 2 has a sampling port 4, which communicates with the inner cavity of the outer tube 101. In a preferred embodiment, the opening 104 of the outer tube 101 extends outward perpendicularly to form a support tube 3, and the nozzle 2 is connected to the outer tube 101 through the support tube 3. The nozzle 2 is funnel-shaped, and the diameter of the sampling port 4 ranges from 350 to 75 μm. The nozzle 2 is connected to the synchrotron radiation photoionization mass spectrometry system through a nickel sieve 7. The cavity formed between the nozzle 2 and the nickel sieve 7 is a differential pumping chamber 8. The main function of the nozzle 2 is to achieve micro-orifice flow restriction through the sampling port 4, control the gas flow rate entering the differential pumping chamber 8, and thus maintain the ionization chamber at a suitable working pressure. The main function of the differential pumping chamber 8 is to establish a pressure gradient between the high-pressure sampling zone of nozzle 2 and the ultra-high vacuum zone of the ionization chamber. By reducing the gas flow rate through stepwise pumping, it ensures that the ionization chamber can maintain a stable low-pressure environment, thereby improving the sensitivity and stability of detection. During the catalytic reaction, by controlling the axial displacement of the inner tube 102 relative to the outer tube 101, the sampling holes 103 at different positions on the inner tube 102 are sequentially directed toward the opening 104 of the outer tube 101, and then connected to the sampling port 4. This allows the intermediates and products located along the catalyst bed in the inner tube 102 during the reaction to be extracted from the nozzle 2 and detected in real time, thus achieving multi-point sampling and obtaining spatial distribution information of the reaction path.

[0047] The inner tube 102 has multiple sampling holes 103 axially arranged in the area where the catalyst bed is arranged. The sampling holes 103 are distributed to cover the inlet, middle section and outlet areas of the catalyst bed. The specific number and spacing of the sampling holes 103 can be set according to experimental needs to obtain the composition of gaseous products representing different reaction stages. One end of the inner tube 102 is connected to a reaction raw material gas supply pipeline. Preferably, the reaction raw material gas supply pipeline includes a carrier gas pipeline 12 and a reaction gas pipeline 14. The carrier gas pipeline 12 and the reaction gas pipeline 14 are connected to one end of the inner tube 102 through a first tee connector 15. The other end of the inner tube 102 is connected to a second tee connector 16. The other two connectors 131 of the second tee connector 16 are respectively connected to a needle valve 17 and a vacuum gauge 18.

[0048] The heating device 5 includes a heating jacket 50 and a housing 57 for fixing the heating jacket 50. The heating jacket 50 includes a lower base 51 and an upper base 52 with identical structures and symmetrical arrangement. The top of the lower base 51 has a T-shaped groove, which includes a horizontal groove 53 for accommodating the outer tube 101 and a vertical groove 54 for accommodating the nozzle 2. The bottom of the T-shaped groove has a through hole penetrating the lower base 51, which is used to arrange a temperature monitoring element. A heating wire 55 is installed on the side wall of the horizontal groove 53. The housing 57 covers the outside of the heating jacket 50 and is fixed to the top of the support frame 6. The heating jacket 50 is preferably made of mullite ceramic fiber material, and a thermocouple 56 is installed in the through hole.

[0049] In a preferred embodiment, the nozzle 2 is connected to the nickel-plated strainer 7 via a flange 9; the flange 9 is fixedly connected to the support frame 6; a connecting plate 10 is provided between the nozzle 2 and the flange 9; the nozzle 2, the connecting plate 10, and the flange 9 are sealed together; a connector 11 is connected to one side of the bottom of the support frame 6, and the connecting plate 10 is fixedly connected to the support frame 6 via the connector 11. The flange 9 is fixed by the support frame 6 fixing the support plate. Specifically, the connector 11 can use a screw hole and bolt connection to fix the connecting plate 10 to the support frame 6.

[0050] Example 2

[0051] An in-situ catalytic reaction method capable of multi-point sampling is carried out using the catalytic reaction system described in Example 1 above, and includes the following steps:

[0052] The tubular reactor is heated using a heating device to bring the temperature to the catalytic reaction temperature.

[0053] The reactant gas is delivered to the inner tube through the reactant gas supply pipeline for reaction.

[0054] The inner tube has multiple sampling holes along its axial direction in the area where the catalyst bed is arranged. These sampling holes are distributed to cover the inlet, middle, and outlet areas of the catalyst bed. The specific number and spacing of the sampling holes can be set according to experimental needs to obtain the composition of gaseous products representing different reaction stages. During the catalytic reaction, by controlling the axial displacement of the inner tube relative to the outer tube, the sampling holes at different positions on the inner tube sequentially face the opening of the outer tube. Since the opening is connected to the sampling port, reactants at different locations can enter the nozzle from the sampling port, and finally pass through a nickel strainer into the detection device for real-time monitoring, thereby obtaining the spatial distribution information of the reaction path.

[0055] The catalytic reaction system described in Example 1 of this invention was applied to the study of methane oxygen-free aromatization (MDA) reaction. The inner tube, outer tube, and nozzle were all made of quartz. Two sampling holes were arranged along the gas flow direction on the tube wall, located at the inlet (initial stage of reaction) and outlet (final stage of reaction) of the reaction bed in the inner tube, respectively. The quartz nozzle was connected to a synchrotron radiation photoionization mass spectrometer (SR-PIMS). Rapid multi-point sampling was achieved by manipulating the inner tube, thus enabling online detection of gaseous products. The reaction gases were methane and argon, which were respectively supplied to the inner tube from the reaction gas pipeline and the carrier gas pipeline for the reaction. The inlet flow rates were 30 sccm for methane and 10 sccm for argon. The reaction temperature was 700 °C, the reaction pressure was atmospheric pressure, and the photoionization energy was 11.5 eV. Considering the activation period of the MDA reaction, multi-point sampling was performed along the gas flow direction at different reaction stages (5–30 min) to capture the abundance changes of gaseous products in real time.

[0056] When the reaction has proceeded for 5 minutes, the test results are as follows: Figure 8 As shown in Figure A, the signal intensities of acetylene (m / z 26) and formaldehyde (m / z 30) in the initial stage of the reaction are significantly higher than those in the final stage of the reaction, while the signal of ethylene (m / z 28) remains essentially unchanged, and the signal intensity of benzene (m / z 78) increases significantly in the final stage of the reaction. This indicates that in the initial stage of the reaction, methane mainly undergoes dehydrogenation and partial oxidation processes, generating oxygen-containing intermediates and C2 species such as acetylene; while the aromatization reaction has not yet fully proceeded.

[0057] When the reaction was extended to 30 minutes, the test results were as follows: Figure 9 As shown in Figure A, the signal intensities of acetylene and ethylene detected in the initial stage of the reaction are still higher than those in the final stage of the reaction shown in Figure B, but the formaldehyde signal almost disappears, indicating the end of catalyst activation. The benzene signal further strengthens in the final stage of the reaction. This result indicates that as the reaction proceeds, oxygen-containing intermediates are gradually converted or consumed by the catalyst surface, and the reaction pathway progresses step by step from "methane → oxygen-containing intermediate / C2 species → aromatic hydrocarbons".

[0058] Overall, the reactor exhibits a clear spatial distribution characteristic along the gas flow direction: the front section is dominated by the generation of C2 intermediates, while the rear section is dominated by the accumulation of aromatization products. This indicates that the catalytic reaction system can effectively capture the spatiotemporal evolution information of key intermediates during the MDA reaction, verifying the real-time multi-point sampling and non-disturbance analysis capabilities of the system of this invention.

[0059] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A catalytic reaction system capable of multi-point sampling, characterized by, The catalytic reaction system comprises a support frame, a tubular reactor fixed on the support frame, and a heating device for heating the tubular reactor. The tubular reactor comprises an outer tube and an inner tube coaxially nested in the outer tube; the two ends of the inner tube protrude out of the outer tube; the two ends of the outer tube are movably connected with the inner tube through a sealing movable mechanism; The inner tube is provided with a plurality of sampling holes in the axial direction at the region where the catalyst bed is arranged; The middle part of the outer tube is provided with an opening, and a nozzle is connected to the opening; the tip of the nozzle is provided with a sampling port which is in communication with the inner cavity of the outer tube; the nozzle is connected with a nickel-made scoop and a synchrotron radiation photoionization mass spectrometry system; a cavity formed between the nozzle and the nickel-made scoop is a differential pumping chamber; One end of the inner tube is connected with a reaction raw gas supply pipeline. The nozzle is connected with the nickel-made scoop through a flange; the flange is fixedly connected with the support frame; a connecting plate is arranged between the nozzle and the flange; the nozzle, the connecting plate and the flange are in sealed connection; one side of the bottom of the support frame is connected with a connecting piece, and the connecting plate is fixedly connected with the support frame through the connecting piece.

2. The catalytic reaction system capable of achieving multipoint sampling according to claim 1, wherein, The sealing movable mechanism comprises a joint fixedly sleeved on the outer side of the outer tube; the joint is sealingly connected with the outer tube; the two ends of the joint are a first threaded end and a second threaded end; the first threaded end is connected with the inner tube through a first sealing assembly; the second threaded end is connected with the inner tube through a second sealing assembly.

3. The catalytic reaction system capable of achieving multipoint sampling according to claim 1, wherein, The first sealing assembly comprises a first sealing gasket and a first pressing ring sleeved on the outer side of the inner tube, and a first nut threadedly connected with the first threaded end; the first sealing gasket and the first pressing ring are located between the first threaded end and the inner tube; the second sealing assembly comprises a second sealing gasket and a second pressing ring sleeved on the outer side of the inner tube, and a second nut threadedly connected with the second threaded end. The opening of the outer tube extends outward perpendicularly to the outer tube to form a support tube, and the nozzle is connected with the outer tube through the support tube; the nozzle is funnel-shaped; the tip of the nozzle is the sampling port.

4. The catalytic reaction system capable of achieving multipoint sampling according to claim 1, wherein, The heating device comprises a heating sleeve and a shell for fixing the heating sleeve; 5. The catalytic reaction system capable of achieving multipoint sampling according to claim 1, wherein, The heating sleeve comprises a lower base and an upper base which are the same in structure and symmetrically arranged; the top of the lower base is provided with a T-shaped groove, which comprises a horizontal groove for accommodating the outer tube and a vertical groove for accommodating the nozzle; a heating wire is mounted on the side wall of the horizontal groove; the shell is wrapped on the outside of the heating sleeve, and the shell is fixed on the top of the support frame. The material of the heating sleeve is mullite ceramic fiber material.

6. The catalytic reaction system capable of multipoint sampling according to claim 5, wherein, The bottom of the T-shaped groove is provided with a through hole penetrating through the lower base; a thermocouple is arranged in the through hole.

7. The catalytic reaction system capable of multipoint sampling according to claim 5, wherein, The reaction raw gas supply pipeline comprises a carrier gas pipeline and a reaction gas pipeline; the carrier gas pipeline and the reaction gas pipeline are connected with one end of the inner tube through a first three-way joint.

8. The catalytic reaction system capable of multipoint sampling according to claim 1, wherein, The other end of the inner tube is connected with a second three-way joint, and the other two joints of the second three-way joint are respectively connected with a needle valve and a vacuum gauge.

9. The catalytic reaction system capable of multipoint sampling according to claim 1, wherein, The method is performed by using the catalytic reaction system according to any one of claims 1 to 9, and comprises the following steps:

10. An in-situ catalytic reaction process capable of enabling multipoint sampling, characterized by, ​ The tubular reactor is heated by the heating device to reach the catalytic reaction temperature; The reaction raw gas is delivered into the inner tube through the reaction raw gas supply pipeline to react, Based on the fact that the inner tube has multiple sampling holes in the region where the catalyst bed is arranged along the axial direction; by making the sampling holes distributed over the inlet, middle and outlet regions of the catalyst bed, during the catalytic reaction, by controlling the axial displacement of the inner tube relative to the outer tube, the sampling holes at different positions on the inner tube are sequentially directed towards the openings of the outer tube, i.e. the intermediates and products located in the catalyst bed along the path in the inner tube during the reaction are guided out of the nozzle and can be detected in real time, so as to obtain the spatial distribution information of the reaction path.

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