Heating transmission device suitable for in-situ detection of ultrahigh-temperature pyrolytic reaction

Abstract

The invention discloses a heating transmission device suitable for in-situ detection of an ultrahigh-temperature pyrolysis reaction. The heating transmission device comprises a heating pipe and an adjusting assembly, the sample outlet end of the heating pipe can be connected with a detection device; the heating pipe is divided into a low-temperature area, a high-temperature area and an annealing area, the low-temperature area is sleeved with a first water-cooled electrode, and the annealing area is sleeved with a second water-cooled electrode; the adjusting assembly comprises a guide rail and a sliding block, and the sliding block is connected with the first water-cooled electrode or connected with the first water-cooled electrode. According to the invention, a variable-diameter and variable-temperature area is formed through the combined design of the heating tube and the water-cooled electrode, so that the contact between the heating tube and the protective electrode is ensured, a slow and uniform cooling gradient is constructed in the annealing area, the generation and dispersion of product molecules are ensured, and the transmission efficiency of high-molecular-weight compounds is improved. The device is convenient to connect with a mass spectrometer, can realize in-situ analysis of ultrahigh-temperature pyrolytic reaction, and solves the problem that high-molecular-weight products such as polycyclic aromatic hydrocarbon, fullerene and the like in the pyrolytic reaction are gathered due to intermolecular force and cannot be detected in situ.

Description

Technical Field

[0001] The present invention specifically relates to a heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reactions. Background Art

[0002] Pyrolysis refers to the process of using high temperature to cause organic matter to undergo chemical reactions under oxygen-deficient or oxygen-free conditions. Studying the mechanism of pyrolysis reactions is of great significance in improving energy efficiency, reducing environmental pollution, developing new materials, process improvement and industrial applications. Pyrolysis reactions are complex multiphase and heterogeneous reaction systems. Studying their mechanisms can promote the development of physical chemistry, thermodynamics and kinetics, and greatly promote basic scientific research. Constructing accurate reaction models through mechanism research can also provide a scientific basis for industrial production processes and guide production.

[0003] The key to determining the mechanism of pyrolysis reaction lies in the capture and characterization of active intermediates during the reaction process. The introduction of capture agents into the reaction system can stabilize the metastable active substances, but the introduction of substances unrelated to the reaction may change the course of the reaction and affect the pyrolysis reaction. The advantage of in-situ detection is that it can be analyzed directly in the original position or environment of the reaction, and the reaction intermediates can be directly detected without processing or transferring the reaction products, which is closer to the actual state of the reaction. Some pyrolysis reactions require high-temperature annealing conditions to generate the target products. General tube furnaces cannot withstand excessively high temperatures (greater than 1200°C). Moreover, if the temperature gradient is not controlled during the annealing process, the reaction products will agglomerate rapidly due to intermolecular forces. Therefore, this phenomenon is quite unfavorable for in-situ detection, which may cause the originally generated products to be undetectable, and the solid particles generated by agglomeration may affect the subsequent reactions. Summary of the invention

[0004] The object of the present invention is to overcome the shortcomings of the prior art and provide a method for solving the problem that in the above-mentioned background technology, polycyclic aromatic hydrocarbons, fullerenes and other large molecular weight compounds generated during the annealing process of the pyrolysis reaction have strong intermolecular forces (π-π interactions), and during the cooling process, the product molecules will aggregate and solidify on the wall of the transmission tube, making it impossible for the mass spectrometer to detect these large molecular weight compounds.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction is provided, comprising a heating tube and an adjustment component; the heating tube comprises an injection end and an output end, the output end is used to connect a detection device; the heating tube is divided into a low temperature zone, a high temperature zone and an annealing zone in sequence according to the distance from the injection end, a first water-cooled electrode is arranged outside the low temperature zone, and a second water-cooled electrode is arranged outside the annealing zone; the adjustment component comprises a guide rail and a sliding block, the sliding block is arranged on the guide rail and connected to the first water-cooled electrode.

[0006] In the present invention, the outer diameters of the low-temperature zone and the annealing zone increase toward the high-temperature zone, and the tube lengths of the zones are from short to long, namely, the high-temperature zone, the annealing zone, and the low-temperature zone; the contact area between the first water-cooled electrode and the low-temperature zone is greater than the contact area between the second water-cooled electrode and the annealing zone.

[0007] In the present invention, the first water-cooled electrode and the second water-cooled electrode are grooved on one side close to the high temperature zone, and protective electrodes are arranged in the grooves.

[0008] In the present invention, the material of the heating tube and the protective electrode includes graphite. Graphite has a high melting point and meets the needs of ultra-high temperature. It also has good electrical conductivity and is convenient for adding current to increase temperature. The material of the first water-cooled electrode and the second water-cooled electrode includes copper.

[0009] In the present invention, the sample inlet end of the heating tube is connected to the sample inlet pipeline via a ferrule adapter.

[0010] In the present invention, a small hole is provided at the sample outlet, the detection device comprises a mass spectrometer, and the sample outlet is connected to the mass spectrometer via a sampling cone.

[0011] In the present invention, the first water-cooled electrode and the second water-cooled electrode are connected to a heating power source, and a circulating water channel is provided inside the first water-cooled electrode and the second water-cooled electrode.

[0012] In the present invention, the adjustment assembly includes a guide rail, a fixed block and a sliding block. The guide rail and the heating tube are arranged in parallel. The sliding block and the fixed block are arranged on the guide rail and are insulated and connected to the first water-cooled electrode and the second water-cooled electrode respectively.

[0013] In the present invention, the adjustment component further comprises a base plate, the guide rail is fixed on the base plate, the guide rail is a screw rod, the sliding block is sleeved on the screw rod through a bearing, and a hand wheel is provided at the end of the screw rod.

[0014] In the present invention, the heating tube is arranged in the vacuum reaction chamber.

[0015] Compared with the background technology, this technical solution has the following advantages:

[0016] 1. The present invention adopts a graphite heating tube with a variable diameter design, and the high temperature zone has a wide temperature rise range, up to 3000°C, which can meet the ultra-high temperature pyrolysis reaction of extreme high temperature; and can effectively control the temperature gradient of the annealing area, ensuring the formation of products while avoiding molecular aggregation, greatly improving the transmission efficiency of the products, and allowing large molecular weight compounds to enter the mass spectrometer for detection;

[0017] 2. The asymmetric and adjustable water-cooled copper electrode of the present invention is used as a cooling design, combined with the diameter and area length design of the graphite heating tube, which not only realizes the protection of the copper electrode by water cooling due to the high reaction temperature of ultra-high temperature pyrolysis, but also can adjust the temperature gradient of the heating tube area according to different reaction systems;

[0018] 3. On the one hand, the present invention utilizes the heat in the center of the high temperature zone to be conducted to the two end areas through the graphite heating tube itself. On the other hand, a cylindrical graphite electrode (a hole can be punched in the middle to allow the graphite tube to pass through) is arranged near the high temperature zone of the water-cooled motor. The graphite electrode is used to separate the high temperature zone from the copper electrode, thereby avoiding direct contact between the copper electrode and the high temperature zone, which may melt the copper electrode. Secondly, if the high temperature zone contacts the colder water-cooled copper electrode, the outlet temperature will drop sharply, which will increase the possibility of molecular aggregation. Therefore, this risk is reduced after isolation, ensuring the gradient change of the temperature in the high temperature zone and the temperature in the two end areas;

[0019] 4. The sampling end of the low temperature zone of the present invention is connected to the external pipeline through a graphite tube to ferrule adapter, which has strong sealing performance, can increase the beam intensity, and is conducive to sampling and detection.

[0020] 5. The present invention is convenient for connection with a sampling cone and a mass spectrometer, and the small hole at the end of the tube can improve the pressure tolerance, thereby realizing in-situ detection of pyrolysis reactions at higher pressures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of the embodiment device.

[0022] Figure 2 Schematic diagram of the structure of the graphite tube of the embodiment.

[0023] Figure 3 It is a schematic diagram of the actual use of the embodiment.

[0024] Figure 4 (a) and (b) are the in-situ detection results of the embodiment device connected to a mass spectrometer.

[0025] Among them, 1-graphite heating tube; 2-protective electrode (right); 3-protective electrode (left); 4-second copper electrode (right); 5-first water-cooled copper electrode (left); 6-ferrule adapter; 7-insulating block; 8-fixed block; 9-sliding block; 10-bearing; 11-base plate; 12-handwheel; 13-screw. DETAILED DESCRIPTION

[0026] The present invention is described below in conjunction with the accompanying drawings and embodiments. The terms "horizontal", "left", "right", etc., indicating directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] Example

[0028] This embodiment provides a heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction, including a graphite heating tube 1 and an adjustment component. Figure 1 The graphite heating tube 1 is placed horizontally, including a sample inlet end at the left end and a sample outlet end 1 at the right end. The sample outlet end 1 is provided with a small hole for connecting a detection device; the graphite heating tube 1 is divided into a low-temperature zone, a high-temperature zone and an annealing zone according to the distance from the sample inlet end (i.e. from left to right), a first water-cooled electrode 5 is arranged outside the low-temperature zone, and a second water-cooled electrode 4 is arranged outside the annealing zone.

[0029] like Figure 2 In this embodiment, the graphite heating tube 1 has the largest diameter in the high temperature zone, and the diameter of the low temperature zone and the annealing zone increases towards the high temperature zone. The tube length is 114mm, the outer diameter is 8mm, the inner diameter is 6mm, and the outer diameter of the central high temperature zone is 10mm. The tube lengths of each zone are 10mm in the high temperature zone, 41mm in the annealing zone, and 63mm in the low temperature zone from short to long. A 1mm small hole is opened at the end of the annealing zone.

[0030] The first water-cooled electrode 5 and the second water-cooled electrode 4 are connected to a heating power source, and a circulating water channel is provided inside the first water-cooled electrode 5 and the second water-cooled electrode 4. The first water-cooled electrode 5 and the second water-cooled electrode 4 adopt an asymmetric design, and the material is copper. The contact area between the first water-cooled electrode 5 and the low-temperature zone is greater than the contact area between the second water-cooled electrode 4 and the annealing zone. Because the cooling effect is related to the contact area, in order to maintain the temperature of the annealing zone, a smaller water-cooled copper electrode is used for water cooling, so that the temperature reduction gradient is gentler; the left low-temperature zone is the end where the reactants are introduced, and high temperature is not required, so a larger water-cooled copper electrode is used to keep its temperature as low as possible. The first water-cooled electrode 5 and the second water-cooled electrode 4 are grooved on the side close to the high-temperature zone, and protective electrodes 2 and 3 are arranged in the groove. In this embodiment, the protective electrodes 2 and 3 are graphite electrodes, which are 18 mm long cylinders with holes in the middle to allow the graphite heating tube 1 to pass through. The high-temperature zone is separated from the water-cooled copper electrode by the graphite electrode. Firstly, direct contact between the water-cooled copper electrode and the high-temperature zone is avoided, which may melt the copper. Secondly, if the high-temperature zone contacts the cooler water-cooled copper electrode, the outlet temperature will drop sharply, which will increase the possibility of molecular aggregation. Therefore, this risk is reduced after isolation.

[0031] During installation, the graphite heating tube 1 passes through the left and right water-cooled copper electrodes and the left and right graphite electrodes, and the middle variable diameter area is clamped and fixed with the left and right graphite electrodes. The injection end of the heating tube 1 is connected to the injection pipeline through a ferrule adapter 6, which is convenient for injection and sealing. The main heating area of ​​the graphite heating tube 1 is the high temperature zone, that is, the middle variable diameter area, which is the area where the pyrolysis reaction occurs. Its heat can be conducted to both ends through the graphite material, thus forming a temperature gradient that slowly cools down to both sides. Through testing, when the temperature in the high temperature zone is 928°C, the temperature in the annealing zone decreases with the increase of the distance from the high temperature zone, and the temperature at the end is 450°C, and the entire temperature field decreases in gradient relatively gently and evenly. The temperature at this time can disperse the pyrolysis products such as polycyclic aromatic hydrocarbons and fullerene molecules in the form of gas phase, which is conducive to subsequent in-situ sampling and mass spectrometry detection. The heating tube 1 is arranged in the vacuum reaction chamber, the detection device includes a mass spectrometer, the sample outlet 1 is connected to the mass spectrometer through a sampling cone, and the sample outlet 1 is provided with a 1mm circular hole. After passing through the small hole, the pyrolysis product expands rapidly to form a molecular beam and enters the sampling cone to be detected in situ by the mass spectrometer.

[0032] The adjustment assembly includes a guide rail, a fixed block 8 and a sliding block 9, and also includes a bottom plate. The guide rail and the graphite heating tube 1 are arranged in parallel. The sliding block 9 and the fixed block 8 are arranged on the guide rail and are insulated and connected to the insulating block 7 at the bottom of the first water-cooled electrode 5 and the second water-cooled electrode 4 respectively. The adjustment assembly also includes a bottom plate 11. The guide rail is fixed on the bottom plate 11. The guide rail is a screw 13. The sliding block is sleeved on the screw 13 through a bearing 10. The end of the screw 13 is provided with a hand wheel 12. The water-cooled electrode can be moved by rotating the hand wheel 12.

[0033] The method of using this embodiment is as follows:

[0034] 1. Fix the entire device in the vacuum reaction chamber through the bottom plate.

[0035] 2. Connect the power supply wiring to the first water-cooled copper electrode and the second water-cooled copper electrode.

[0036] 3. Turn on the mechanical pump to create a vacuum, introduce carrier gas into the chamber, and provide appropriate reaction pressure.

[0037] 4. Open the gas valve and use a mass flow meter to control the flow rate of raw material steam entering the graphite heating tube 1.

[0038] 5. Turn on the heating power supply and adjust the output current according to the required temperature.

[0039] 6. Measure the temperature and collect data. After the reaction is completed, turn off the power supply and gas valve.

[0040] As the reactants are introduced into the graphite heating tube 1 under appropriate pressure, current is applied to the copper electrodes at both ends of the graphite heating tube 1, causing the graphite heating tube 1 to generate high temperature. By utilizing the principle that the heat from the center of the graphite heating tube 1 is conducted to both sides, a slow and uniform cooling temperature gradient can be constructed by adjusting the distance between the water-cooled copper electrodes and the length of each area of ​​the graphite heating tube 1. The reactants undergo pyrolysis in the high temperature zone, and pyrolysis products such as polycyclic aromatic hydrocarbons and fullerenes are generated through the annealing zone. The annealing zone is maintained at a relatively high temperature to prevent large molecular weight compounds from spontaneously aggregating together due to strong intermolecular forces, thereby affecting subsequent reactions and detection. Subsequently, the dispersed product molecules are rapidly expanded by the high pressure through the small holes and sprayed to the final high vacuum zone to form a molecular beam detected by mass spectrometry.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction, characterized in that: It comprises a heating tube and an adjusting component; the heating tube comprises an injection end and an output end, the output end is used to connect a detection device; the heating tube is divided into a low temperature zone, a high temperature zone and an annealing zone in sequence according to the distance from the injection end, a first water-cooled electrode is arranged outside the low temperature zone, and a second water-cooled electrode is arranged outside the annealing zone; the adjusting component comprises a guide rail and a sliding block, the sliding block is arranged on the guide rail and connected to the first water-cooled electrode.

2. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The outer diameters of the low-temperature zone and the annealing zone increase toward the high-temperature zone, and the tube lengths of the zones are from short to long, namely, the high-temperature zone, the annealing zone, and the low-temperature zone; the contact area between the first water-cooled electrode and the low-temperature zone is greater than the contact area between the second water-cooled electrode and the annealing zone.

3. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The first water-cooled electrode and the second water-cooled electrode are grooved on one side close to the high-temperature zone, and protective electrodes are arranged in the grooves.

4. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 3, characterized in that: The heating tube and the protective electrode are made of graphite, and the first water-cooling electrode and the second water-cooling electrode are made of copper.

5. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The injection end of the heating tube is connected to the injection pipeline through a ferrule adapter.

6. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The sample outlet is provided with a small hole, the detection device comprises a mass spectrometer, and the sample outlet is connected to the mass spectrometer through a sampling cone.

7. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The first water-cooled electrode and the second water-cooled electrode are connected to a heating power source, and a circulating water channel is provided inside the first water-cooled electrode and the second water-cooled electrode.

8. The heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The adjustment assembly includes a guide rail, a fixed block and a sliding block. The guide rail and the heating tube are arranged in parallel. The sliding block and the fixed block are arranged on the guide rail and are insulated and connected to the first water-cooled electrode and the second water-cooled electrode respectively.

9. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 8, characterized in that: The adjustment component also includes a base plate, the guide rail is fixed on the base plate, the guide rail is a screw rod, the sliding block is sleeved on the screw rod through a bearing, and a hand wheel is provided at the end of the screw rod.

10. The heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reaction according to claim 1, characterized in that: The heating tube is arranged in the vacuum reaction chamber.

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