In-situ pyrolysis device adopting glow ionization source

Abstract

The invention provides an in-situ pyrolysis device adopting a glow ionization source. The in-situ pyrolysis device comprises a high-temperature pyrolysis device, a glow ionization device, a two-stage sampling cone, a quadrupole rod device and a flight time mass analyzer, the high-temperature pyrolysis device comprises a first copper block, a second copper block, a graphite sleeve and a long graphite pipe; the glow ionization device comprises a first electrode fixing cylinder, a second electrode fixing cylinder and an annular electrode; the two-stage sampling cone is divided into a first-stage sampling cone and a second-stage sampling cone; and the quadrupole rod device comprises four quadrupole rod electrodes which are parallel to one another and are symmetrically arranged. Pyrolysis reactants generate fullerene and intermediate products thereof through a high-temperature pyrolysis device, then product molecules are ionized through a glow ionization device, ionized ions pass through a two-stage sampling cone and are guided by a radio-frequency electric field and a direct-current electric field of a quadrupole rod device to reach a time-of-flight mass analyzer for in-situ mass spectrometric analysis, and the mass spectrometric analysis result is obtained. In-situ mass spectrometry analysis of'first ionization and second sampling 'can be realized, and fullerene and intermediates thereof formed by high-temperature pyrolysis can be captured.

Description

Technical Field

[0001] The present invention explores the technical fields of fullerene formation mechanism, glow ionization and in-situ mass spectrometry, and particularly relates to an in-situ pyrolysis device using a glow ionization source. Background Art

[0002] In the current scientific community, there is no unified understanding of the formation mechanism of fullerenes. In situ mass spectrometry can capture the intermediates of small molecular compounds (such as dichloromethane and carbon tetrachloride) that form fullerenes through high-temperature pyrolysis, which provides an opportunity to explore the formation mechanism of fullerenes.

[0003] However, traditional time-of-flight mass spectrometry ionization technologies, such as electron impact ionization (EI) and ultraviolet photoionization (PI), have obvious drawbacks. For example, the ionization energy of EI is too high, which can easily break up the fullerenes and intermediates produced by high-temperature pyrolysis, resulting in complex spectra and difficulty in analysis. In addition, the filaments in the EI ionization source are constantly affected by electron emission and high temperature during operation, and are prone to aging and damage. A certain vacuum working pressure is also required, which increases the cost of using the instrument and the workload of maintenance. For example, the ionization efficiency of PI is low, and some high ionization energy compounds cannot be effectively ionized, which limits the range of substances that can be analyzed, and the signal is weak, making it difficult to effectively capture the intermediates of fullerene formation.

[0004] In addition, the atmosphere pressure of the reaction chamber for high-temperature pyrolysis is about 0.7 kPa, while the vacuum condition required for the normal operation of the mass spectrometer is 1×10 -4 pa, it is inevitable to use multiple sampling cones to achieve vacuum transition. This will inevitably cause the loss of pyrolysis products during the transmission process, thus making it impossible to achieve true in-situ analysis.

[0005] Moreover, fullerenes and their intermediates after high-temperature pyrolysis will undergo molecular collision cooling in the buffer atmosphere or on the surface of the sampling cone during the transmission process, resulting in the loss of material information of a large amount of intermediates, making it impossible to achieve true in-situ mass spectrometry analysis, which brings challenges to the exploration of the formation mechanism of fullerenes.

[0006] In view of this, the present invention designs a new glow ionization technology combined with in-situ pyrolysis. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides an in-situ pyrolysis device using a glow ionization source, which can realize the in-situ mass spectrometry analysis of "ionization first, then sampling", capture the fullerenes and their intermediates formed by high-temperature pyrolysis, and provide new technical support for the study of the formation mechanism of fullerenes.

[0008] In order to solve the above technical problems, the present invention provides an in-situ pyrolysis device using a glow ionization source, comprising a high-temperature pyrolysis device, a glow ionization device, a two-stage sampling cone, a quadrupole device and a time-of-flight mass analyzer;

[0009] The pyrolysis reactants are passed through the high-temperature pyrolysis device to produce fullerenes and intermediate products thereof, and then the product molecules are ionized by the glow ionization device. The ionized ions pass through the two-stage sampling cone and, under the guidance of the radio frequency electric field and the direct current electric field of the quadrupole device, reach the time-of-flight mass analyzer for in-situ mass spectrometry analysis.

[0010] The high-temperature pyrolysis device comprises a first copper block, a second copper block, a graphite sleeve and a long graphite tube; the graphite sleeves are respectively embedded at opposite ends of the first copper block and the second copper block, and the graphite sleeves are sleeved on the long graphite tube;

[0011] The glow ionization device comprises a first electrode fixing tube, a second electrode fixing tube and an annular electrode; the first electrode fixing tube and the second electrode fixing tube are both provided with a groove, and the groove is used to embed and fix the annular electrode;

[0012] The two-stage sampling cone is divided into a primary sampling cone and a secondary sampling cone, and there is a distance between the primary sampling cone and the secondary sampling cone;

[0013] The quadrupole device comprises four quadrupole electrodes which are parallel to each other and symmetrically arranged.

[0014] In a preferred embodiment, the first copper block and the second copper block are two mushroom-shaped copper blocks of the same size; the first copper block and the second copper block are both made of red copper.

[0015] In a preferred embodiment, the in-situ pyrolysis device further comprises a chamber cover plate; the second copper block is fixed to the chamber cover plate via a base;

[0016] The cavity cover plate includes a guide rail, the first copper block is connected to the guide rail via a slider, and the first copper block is movable along the guide rail.

[0017] In a preferred embodiment, the sampling end of the long graphite tube is connected to the zirconia ceramic tube; the zirconia ceramic tube, the long graphite tube, the primary sampling cone, the secondary sampling cone and the quadrupole device are coaxially arranged.

[0018] In a preferred embodiment, the first electrode fixing tube and the second electrode fixing tube are made of boron nitride; the first electrode fixing tube and the second electrode fixing tube are fixed by a sleeve.

[0019] In a preferred embodiment, the material of the annular electrode is stainless steel; the annular electrode is divided into an inner annular electrode and an outer annular electrode;

[0020] Two groups of outer annular electrodes are provided, and the inner annular electrode is provided between the two groups of outer annular electrodes; a plurality of first through holes are provided around the inner annular electrode, and second through holes are provided at both ends of the outer annular electrode.

[0021] In a preferred embodiment, the lengths of the two groups of outer annular electrodes are both 14 mm, the inner diameter of one group of outer annular electrodes is 20 mm and the outer diameter is 22 mm, and the inner diameter of the other group of outer annular electrodes is 26 mm and the outer diameter is 28 mm;

[0022] The inner electrode ring has an inner diameter of 12 mm, an outer diameter of 14 mm, and a length of 14 mm.

[0023] In a preferred embodiment, the primary sampling cone is provided with a 0.4 mm cone hole, and the secondary sampling cone is provided with a 1 mm cone hole; the spacing between the primary sampling cone and the secondary sampling cone is 15 mm.

[0024] In a preferred embodiment, the quadrupole electrode is a cylindrical stainless steel electrode, and the diameter of the quadrupole electrode is 9 mm and the length is 56 mm;

[0025] A sleeve made of peek material is embedded outside the quadrupole electrode.

[0026] In a preferred embodiment, among the four quadrupole rod electrodes, two opposite quadrupole rod electrodes form a group; and two adjacent quadrupole rod electrodes are applied with a radio frequency voltage with a phase difference of 180° and the same direct current voltage.

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

[0028] 1. The present invention provides an in-situ pyrolysis device using a glow ionization source, including a high-temperature pyrolysis device, a glow ionization device, a two-stage sampling cone, a quadrupole device and a time-of-flight mass analyzer. The present invention can realize an in-situ mass spectrometry analysis technology of ionization first and then sampling, and can avoid the problem that molecular collisions of fullerenes and their intermediates after high-temperature pyrolysis occur during the transmission process, and they are cooled in a buffer atmosphere or on the surface of the sampling cone, resulting in a large amount of material information loss of the intermediates, thereby failing to realize the problem of true in-situ mass spectrometry analysis.

[0029] 2. The present invention provides an in-situ pyrolysis device using a glow ionization source, which can effectively ionize target molecules under low pressure conditions, and can effectively control the ionization energy by precisely controlling the voltage and current of the glow ionization source, thereby reducing the generation of ion fragments and facilitating spectral analysis. It not only makes up for the shortcomings of traditional ionization technology, but also provides more powerful technical support for the exploration of the formation mechanism of fullerenes.

[0030] 3. The present invention provides an in-situ pyrolysis device using a glow ionization source, which has the remarkable characteristics of high efficiency and adjustable ionization energy. It can directly ionize the target product molecules after high-temperature pyrolysis in the reaction chamber, and then transmit them to the mass spectrometer through the sampling cone and quadrupole device. Due to the electrostatic effect of mutual charge repulsion between ions, the collision cooling of the product molecules during the transmission process can be effectively avoided, and the in-situ mass spectrometry analysis of ionization first and then sampling can be realized. In addition, the device can also achieve effective regulation of ionization energy by changing the key parameters such as voltage and current of glow discharge. In this way, a wide energy range can be obtained, thereby successfully ionizing fullerenes and various complex intermediates formed after high-temperature pyrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of an in-situ pyrolysis device in a preferred embodiment of the present invention;

[0032] Figure 2 It is a cross-sectional schematic diagram of an in-situ pyrolysis device in a preferred embodiment of the present invention.

[0033] Explanation of the reference numerals: 1. first copper block; 2. first graphite sleeve; 3. second graphite sleeve; 4. second zirconia ceramic block; 5. base; 6. long graphite tube; 7. first zirconia ceramic block; 8. slider; 9. guide rail; 10. second copper block; 11. first electrode fixing tube; 12. second electrode fixing tube; 13. zirconia ceramic tube; 14. cavity cover; 15. quadrupole electrode; 16. sleeve made of peek material; 17. quadrupole base; 18. primary sampling cone; 19. secondary sampling cone; 20. inner ring electrode; 21. outer ring electrode. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] refer to Figure 1-Figure 2 This embodiment provides an in-situ pyrolysis device using a glow ionization source, including a high-temperature pyrolysis device, a glow ionization device, a two-stage sampling cone, a quadrupole device and a time-of-flight mass analyzer; the pyrolysis reactants pass through the high-temperature pyrolysis device to produce fullerenes and intermediate products thereof, and then the glow ionization device ionizes the product molecules, and the ionized ions pass through the two-stage sampling cones and, under the guidance of the radio frequency electric field and the direct current electric field of the quadrupole device, reach the time-of-flight mass analyzer for in-situ mass spectrometry analysis.

[0038] The high-temperature pyrolysis device provided in this embodiment includes a first copper block 1, a second copper block 10, a graphite sleeve and a long graphite tube 6; the graphite sleeve includes a first graphite sleeve 2 and a second graphite sleeve 3, and the first copper block 1 and the second copper block 10 are respectively inlaid with the first graphite sleeve 2 and the second graphite sleeve 3 at opposite ends, and the graphite sleeve is sleeved on the long graphite tube 6, and the long graphite tube 6 is clamped between the first graphite sleeve 2 and the second graphite sleeve 3 to achieve a good contact effect.

[0039] The sampling end of the long graphite tube 6 is connected to the zirconia ceramic tube 13, and the outer diameter of the zirconia ceramic tube 13 is 6 mm, the inner diameter is 4 mm, and the length is 100 mm. The long graphite tube 6 is closely matched with the zirconia ceramic tube 13, which can achieve the purpose of sampling and can withstand the high temperature of the graphite tube connection.

[0040] The in-situ pyrolysis device also includes a mass spectrometer cavity and a cavity cover 14. The second copper block 10 is fixed to the cavity cover 14 via a stainless steel base 5. The cavity cover 14 includes a guide rail 9. The first copper block 1 is connected to the guide rail 9 via a slider 8. The first copper block 1 is movable along the guide rail 9. The front and rear movement of the first copper block 1 facilitates the disassembly and assembly of the graphite sleeve and the long graphite tube 6.

[0041] The first copper block 1 and the second copper block 10 are two mushroom-shaped copper blocks of the same size; the first copper block 1 and the second copper block 10 are both made of red copper, which has good conductivity. The first copper block 1 and the second copper block 10 are respectively connected to the slider 8 and the stainless steel base 5 through the first zirconia ceramic block 7 and the second zirconia ceramic block 4 to achieve the purpose of insulation and prevent the cavity from conducting electricity during the heating process.

[0042] The dimensions of the first copper block 1 and the second copper block 10 are both 58 mm long, 34 mm wide and 16 mm high. The dimensions of the graphite sleeve are 16 mm in outer diameter, 4 mm in inner diameter and 18 mm in length. The dimensions of the long graphite tube 6 are 4 mm in outer diameter, 2 mm in inner diameter and 93 mm in length. A 1 mm small hole is opened at the end of the long graphite tube 6, and the middle protrusion is 10 mm long and 1 mm thick.

[0043] The glow ionization device provided in this embodiment includes a first electrode fixing tube 11, a second electrode fixing tube 12 and an annular electrode; the first electrode fixing tube 11 and the second electrode fixing tube 12 are made of boron nitride, which can withstand the high temperature of the long graphite tube 6. The first electrode fixing tube 11 and the second electrode fixing tube 12 are fixed by a sleeve with an outer diameter of 50 mm and an inner diameter of 36 mm. Three grooves are provided inside the first electrode fixing tube 11 and the second electrode fixing tube 12, and the grooves are used to embed and fix the annular electrode.

[0044] The material of the annular electrode is stainless steel; the annular electrode is divided into an inner annular electrode 20 and an outer annular electrode 21; the outer annular electrode 21 is arranged in two groups, and the inner annular electrode 20 is arranged between the two groups of the outer annular electrodes 21; the lengths of the two groups of the outer annular electrodes 21 are both 14 mm, one group of the outer annular electrodes 21 has an inner diameter of 20 mm and an outer diameter of 22 mm, and the other group of the outer annular electrodes 21 has an inner diameter of 26 mm and an outer diameter of 28 mm; the inner diameter of the inner ring electrode ring is 12 mm, the outer diameter is 14 mm, and the length is 14 mm.

[0045] The inner ring electrode is provided with a plurality of first through holes, and the plurality of first through holes is provided with 5 circles, and each circle is provided with 16 first through holes. The diameter of the first through hole is 2 mm. Two second through holes are provided at both ends of the outer ring electrode 21, and the diameter of the second through holes is 4 mm. The second through holes are provided to facilitate the connection of wires to the inner ring electrode 20 and the outer ring electrode 21. The inner ring electrode 20 and the outer ring electrode 21 are used together, and the distribution of the electric field can be optimized by changing the spacing distance between the inner ring electrode 20 and the outer ring electrode 21, so as to achieve a better glow ionization effect.

[0046] The two-stage sampling cone provided in this embodiment is divided into a primary sampling cone 18 and a secondary sampling cone 19. There is a distance between the primary sampling cone 18 and the secondary sampling cone 19. The primary sampling cone 18 is provided with a 0.4 mm cone hole, and the secondary sampling cone 19 is provided with a 1 mm cone hole. The distance between the primary sampling cone 18 and the secondary sampling cone 19 is 15 mm. The zirconia ceramic tube 13, the long graphite tube 6, the primary sampling cone 18, the secondary sampling cone 19 and the quadrupole device are coaxially arranged.

[0047] The quadrupole device provided in this embodiment includes four parallel and symmetrically placed quadrupole electrodes 15. The quadrupole electrode 15 is a cylindrical stainless steel electrode with a diameter of 9 mm and a length of 56 mm. The quadrupole electrode 15 is embedded with a sleeve 16 made of peek material and fixed on the mass spectrometer cavity through a stainless steel quadrupole base 17.

[0048] Among the four quadrupole electrodes 15, two opposite quadrupole electrodes 15 form a group; two adjacent quadrupole electrodes 15 apply a radio frequency voltage with a phase difference of 180° and the same direct current voltage. Under the guidance of the radio frequency electric field and the direct current electric field, the ions pass through the quadrupole and reach the time-of-flight mass analyzer to achieve mass-to-charge ratio analysis.

[0049] When the in-situ pyrolysis device using a glow ionization source provided in this embodiment is used, the pyrolysis reactants enter the long graphite tube 6 through the zirconia ceramic tube 13, and the direct current generated by the power supply is conducted to the long graphite tube 6 through the first copper block 1, the second copper block 10, the first graphite sleeve 2 and the second graphite sleeve 3, and a high temperature is generated under the low vacuum condition of 0.7 kPa for pyrolysis reaction. The fullerenes and intermediate products produced after pyrolysis are ionized by the glow ionization device. The specific working principle of the glow ionization device is that a high voltage is applied to the outer annular electrode 21, and a low voltage is applied to the inner annular electrode 20. The buffer gas is excited and ionized in a high electric field to form a plasma between the outer annular electrode 21 and the inner annular electrode 20. Under the action of the electric field, the positive ions are accelerated and pass through the first through hole on the inner annular electrode 20, bombarding the target sample molecules passing through the middle, thereby realizing the ionization of the high-temperature pyrolysis products. The ionized product molecules pass through the primary sampling cone 18 and the secondary sampling cone 19 in turn, and reach the time-of-flight mass analyzer under the guidance of the radio frequency electric field and the direct current electric field applied by the quadrupole electrode 15, thereby realizing in-situ mass spectrometry analysis of the high-temperature pyrolysis products.

[0050] The in-situ pyrolysis device using a glow ionization source provided in this embodiment has the following beneficial effects:

[0051] 1. The glow ionization source technology is used to avoid the traditional EI ionization energy being too high, resulting in more ion fragments, which makes mass spectrum analysis difficult, and solves the problem of low PI ionization efficiency.

[0052] 2. The reaction chamber pressure of the in-situ pyrolysis device suitable for fullerene synthesis is about 0.7 kPa, while glow ionization can also achieve a good ionization effect at 1 kPa, and the voltage and current of the annular electrode can be precisely controlled to obtain a sufficiently wide energy range, which is conducive to the in-situ analysis of complex reaction products.

[0053] 3. The mass spectrometry analysis technology of ionization first and then sampling can avoid molecular collision cooling of fullerenes and their intermediates produced after high-temperature pyrolysis in the buffer atmosphere or on the surface of the sampling cone during transmission, avoid the loss of material information of the reaction intermediates, and realize true in-situ mass spectrometry analysis.

[0054] 4. A two-stage sampling cone is used to realize vacuum transition. The spacing between the primary sampling cone 18 and the secondary sampling cone 19 satisfies the Mach disk distribution, and an ultrasonic molecular beam can be formed with good directivity to reduce background interference.

[0055] 5. The sampling quadrupole electrode 15 guides the transmission efficiency, and the internal electric field distribution is relatively stable, the structure is simple, and the maintenance cost is relatively low.

[0056] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe the protection scope of the present invention.

Claims

1. An in-situ pyrolysis device using a glow ionization source, characterized in that: It includes a high-temperature pyrolysis device, a glow ionization device, a two-stage sampling cone, a quadrupole device and a time-of-flight mass analyzer; The pyrolysis reactants are passed through the high-temperature pyrolysis device to produce fullerenes and intermediate products thereof, and then the product molecules are ionized by the glow ionization device. The ionized ions pass through the two-stage sampling cone and, under the guidance of the radio frequency electric field and the direct current electric field of the quadrupole device, reach the time-of-flight mass analyzer for in-situ mass spectrometry analysis. The high-temperature pyrolysis device comprises a first copper block, a second copper block, a graphite sleeve and a long graphite tube; the graphite sleeves are respectively embedded at opposite ends of the first copper block and the second copper block, and the graphite sleeves are sleeved on the long graphite tube; The glow ionization device comprises a first electrode fixing tube, a second electrode fixing tube and an annular electrode; the first electrode fixing tube and the second electrode fixing tube are both provided with a groove, and the groove is used to embed and fix the annular electrode; The two-stage sampling cone is divided into a primary sampling cone and a secondary sampling cone, and there is a distance between the primary sampling cone and the secondary sampling cone; The quadrupole device comprises four quadrupole electrodes which are parallel to each other and symmetrically arranged.

2. The in-situ pyrolysis device using a glow ionization source according to claim 1, characterized in that: The first copper block and the second copper block are two mushroom-shaped copper blocks of the same size; the first copper block and the second copper block are both made of red copper.

3. The in-situ pyrolysis device using a glow ionization source according to claim 2, characterized in that: The in-situ pyrolysis device further comprises a cavity cover plate; the second copper block is fixed to the cavity cover plate via a base; The cavity cover plate includes a guide rail, the first copper block is connected to the guide rail via a sliding block, and the first copper block is movable along the guide rail.

4. The in-situ pyrolysis device using a glow ionization source according to claim 1, characterized in that: The sampling end of the long graphite tube is connected to the zirconia ceramic tube; the zirconia ceramic tube, the long graphite tube, the primary sampling cone, the secondary sampling cone and the quadrupole device are coaxially arranged.

5. The in-situ pyrolysis device using a glow ionization source according to claim 1, characterized in that: The first electrode fixing tube and the second electrode fixing tube are made of boron nitride; the first electrode fixing tube and the second electrode fixing tube are fixed by a sleeve.

6. The in-situ pyrolysis device using a glow ionization source according to claim 1, characterized in that: The material of the annular electrode is stainless steel; the annular electrode is divided into an inner annular electrode and an outer annular electrode; Two groups of outer annular electrodes are provided, and the inner annular electrode is provided between the two groups of outer annular electrodes; a plurality of first through holes are provided around the inner annular electrode, and second through holes are provided at both ends of the outer annular electrode.

7. The in-situ pyrolysis device using a glow ionization source according to claim 6, characterized in that: The length of the two groups of outer ring electrodes is 14 mm, the inner diameter of one group of outer ring electrodes is 20 mm and the outer diameter is 22 mm, and the inner diameter of the other group of outer ring electrodes is 26 mm and the outer diameter is 28 mm; The inner electrode ring has an inner diameter of 12 mm, an outer diameter of 14 mm, and a length of 14 mm.

8. The in-situ pyrolysis device using a glow ionization source according to claim 1, characterized in that: The first-level sampling cone is provided with a 0.4mm cone hole, and the second-level sampling cone is provided with a 1mm cone hole; the spacing between the first-level sampling cone and the second-level sampling cone is 15mm.

9. The in-situ pyrolysis device using a glow ionization source according to claim 1, characterized in that: The quadrupole electrode is a cylindrical stainless steel electrode with a diameter of 9 mm and a length of 56 mm; A sleeve made of peek material is embedded outside the quadrupole electrode.

10. The in-situ pyrolysis device using a glow ionization source according to claim 9, characterized in that: Among the four quadrupole rod electrodes, two opposite quadrupole rod electrodes form a group; two adjacent quadrupole rod electrodes are applied with a radio frequency voltage with a phase difference of 180° and the same direct current voltage.

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