An in-situ pyrolysis device using a glow ionization source

Abstract

This invention provides an in-situ pyrolysis device using a glow discharge photoionization source, comprising a high-temperature pyrolysis device, a glow discharge photoionization device, two-stage sampling cones, a quadrupole device, and a time-of-flight mass analyzer. The high-temperature pyrolysis device includes a first copper block, a second copper block, a graphite sleeve, and a long graphite tube. The glow discharge photoionization device includes a first electrode fixing cylinder, a second electrode fixing cylinder, and a ring electrode. The two-stage sampling cones are divided into a first-stage sampling cone and a second-stage sampling cone. The quadrupole device includes four parallel and symmetrically placed quadrupole electrodes. The pyrolysis reactants generate fullerenes and their intermediate products through the high-temperature pyrolysis device. The product molecules are then ionized by the glow discharge photoionization device. The ionized ions pass through the two-stage sampling cones and, guided by the radio frequency electric field and DC electric field of the quadrupole device, reach the time-of-flight mass analyzer for in-situ mass spectrometry analysis. This allows for "ionization first, sampling later" in-situ mass spectrometry analysis, capturing the fullerenes and their intermediates formed by high-temperature pyrolysis.

Description

Technical Field

[0001] This invention explores the technical fields of fullerene formation mechanism, glow discharge photoionization, and in-situ mass spectrometry, and particularly relates to an in-situ pyrolysis device using a glow discharge photoionization source. Background Technology

[0002] In-situ mass spectrometry can capture intermediates of small molecule 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 techniques, such as electron impact ionization (EI) and ultraviolet photoionization (PI), have significant drawbacks. For example, EI's high ionization energy easily breaks down fullerenes and intermediates produced by high-temperature pyrolysis, resulting in complex and difficult-to-analyze spectra. Furthermore, the filament in an EI ionization source is constantly subjected to electron emission and high temperatures during operation, making it prone to aging and damage. It also requires a certain vacuum operating pressure, increasing the instrument's operating cost and maintenance workload. PI, on the other hand, has low ionization efficiency, failing to effectively ionize some high-ionization-energy compounds, limiting the range of analyzable substances, and its weak signal makes it difficult to effectively capture fullerene-forming intermediates.

[0004] Furthermore, the atmospheric pressure during the high-temperature pyrolysis in the reaction chamber is around 0.7 kPa, while the vacuum condition required for the normal operation of the mass spectrometer is 1 × 10⁻⁶ kPa. -4 In pyrolysis, multiple sampling cones are inevitably used to achieve vacuum transition. This inevitably leads to the loss of pyrolysis products during transport, thus preventing true in-situ analysis.

[0005] Moreover, fullerenes and their intermediates after high-temperature pyrolysis undergo molecular collisions and cooling in a buffer atmosphere or on the surface of the sampling cone during transport, resulting in the loss of material information of a large number of intermediates, thus making it impossible to achieve true in-situ mass spectrometry analysis. This poses a challenge to the investigation of the formation mechanism of fullerenes.

[0006] In view of this, the present invention designs a novel glow discharge photoionization technology that combines in-situ pyrolysis. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an in-situ pyrolysis device employing a glow discharge photoionization source, which enables in-situ mass spectrometry analysis of "ionization before sampling," capturing fullerenes and their intermediates formed by high-temperature pyrolysis, and providing new technical support for the study of fullerene formation mechanisms.

[0008] To solve the above-mentioned technical problems, the present invention provides an in-situ pyrolysis device using a glow discharge photoionization source, including a high-temperature pyrolysis device, a glow discharge photoionization device, a two-stage sampling cone, a quadrupole device, and a time-of-flight mass analyzer.

[0009] The pyrolysis reactants produce fullerenes and their intermediate products through the high-temperature pyrolysis device. The product molecules are then ionized by the glow discharge photoionization device. The ionized ions pass through the two-stage sampling cone and, guided by the radio frequency electric field and DC 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 includes a first copper block, a second copper block, a graphite sleeve, and a long graphite tube; the graphite sleeve is respectively embedded at one end of the first copper block and the second copper block, and the graphite sleeve is fitted onto the long graphite tube;

[0011] The glow discharge photoionization device includes a first electrode fixing cylinder, a second electrode fixing cylinder, and an annular electrode; both the first electrode fixing cylinder and the second electrode fixing cylinder are provided with grooves, which are 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 gap between the primary sampling cone and the secondary sampling cone;

[0013] The quadrupole device includes four quadrupole electrodes that are parallel to each other and symmetrically placed.

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

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

[0016] The cavity cover includes a guide rail, and 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 sample inlet end of the long graphite tube is connected to a 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 cylinder and the second electrode fixing cylinder are made of boron nitride; the first electrode fixing cylinder and the second electrode fixing cylinder are fixed by a sleeve engagement.

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

[0020] Two sets of outer annular electrodes are provided, and the inner annular electrodes are provided between the two sets of outer annular electrodes; the inner annular electrodes are provided with a plurality of first through holes, and the two ends of the outer annular electrodes are provided with second through holes.

[0021] In a preferred embodiment, the length of both sets of outer annular electrodes is 14 mm, one set of outer annular electrodes has an inner diameter of 20 mm and an outer diameter of 22 mm, and the other set of outer annular electrodes has an inner diameter of 26 mm and an outer diameter of 28 mm.

[0022] The inner annular electrode 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 has a 0.4 mm conical hole, and the secondary sampling cone has a 1 mm conical hole; the distance between the primary and secondary sampling cones is 15 mm.

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

[0025] The quadrupole electrode is nested with a sleeve made of PEEK material.

[0026] In a preferred embodiment, two opposite quadrupole electrodes are grouped together; adjacent quadrupole electrodes are subjected to a radio frequency voltage with a 180° phase difference and the same DC voltage.

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

[0028] 1. This invention provides an in-situ pyrolysis device using a glow discharge photoionization source, comprising a high-temperature pyrolysis device, a glow discharge photoionization device, a two-stage sampling cone, a quadrupole device, and a time-of-flight mass analyzer. This invention enables in-situ mass spectrometry analysis by prior ionization followed by sampling, avoiding the problem of molecular collisions occurring during the transport of fullerenes and their intermediates after high-temperature pyrolysis, and the loss of material information for a large number of intermediates due to cooling in a buffer atmosphere or on the surface of the sampling cone, thus preventing true in-situ mass spectrometry analysis.

[0029] 2. This invention provides an in-situ pyrolysis device using a glow discharge photoionization source, which can effectively ionize target molecules under low pressure conditions. Furthermore, by precisely controlling the voltage and current of the glow discharge photoionization source, the ionization energy can be effectively controlled, reducing the generation of ion fragments and facilitating spectral analysis. This not only makes up for the shortcomings of traditional ionization technology but also provides stronger technical support for the study of the fullerene formation mechanism.

[0030] 3. This invention provides an in-situ pyrolysis device employing a glow discharge ionization source, which possesses significant advantages in terms of high efficiency and adjustable ionization energy. It can directly ionize target product molecules after high-temperature pyrolysis within the reaction chamber, and then transmit them to a mass spectrometer via a sampling cone and quadrupole device. Due to the electrostatic repulsion between ions, collisional cooling of product molecules during transmission is effectively avoided, enabling in-situ mass spectrometry analysis with ionization preceding sampling. Furthermore, this device can effectively control the ionization energy by altering key parameters such as the voltage and current of the glow discharge. This allows for a wide energy range to be obtained, thus successfully ionizing fullerenes and various complex intermediates formed after high-temperature pyrolysis. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the in-situ pyrolysis apparatus in a preferred embodiment of the present invention;

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

[0033] Explanation of reference numerals in the attached drawings: 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 sleeve; 12. Second electrode fixing sleeve; 13. Zirconia ceramic tube; 14. Cavity cover plate; 15. Quadrupole electrode; 16. PEEK sleeve; 17. Quadrupole base; 18. First-stage sampling cone; 19. Second-stage sampling cone; 20. Inner annular electrode; 21. Outer annular electrode. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," 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 on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. 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 a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0037] refer to Figure 1-Figure 2 This embodiment provides an in-situ pyrolysis device using a glow discharge photoionization source, including a high-temperature pyrolysis device, a glow discharge photoionization device, a two-stage sampling cone, a quadrupole device, and a time-of-flight mass analyzer. The pyrolysis reactants produce fullerenes and their intermediate products through the high-temperature pyrolysis device, and then the glow discharge photoionization device ionizes the product molecules. The ionized ions pass through the two-stage sampling cone and, guided by the radio frequency electric field and DC 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. The first graphite sleeve 2 and the second graphite sleeve 3 are respectively embedded at opposite ends of the first copper block 1 and the second copper block 10. The graphite sleeve is fitted onto 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 sample inlet end of the long graphite tube 6 is connected to a zirconia ceramic tube 13. The zirconia ceramic tube 13 has an outer diameter of 6 mm, an inner diameter of 4 mm, and a length of 100 mm. The long graphite tube 6 and the zirconia ceramic tube 13 fit together tightly, which can achieve the purpose of sample introduction and withstand the high temperature at the graphite tube connection.

[0040] The in-situ pyrolysis device also includes a mass spectrometry chamber and a chamber cover plate 14. The second copper block 10 is fixed to the chamber cover plate 14 by a stainless steel base 5. The chamber cover plate 14 includes a guide rail 9. The first copper block 1 is connected to the guide rail 9 by a slider 8. The first copper block 1 can move along the guide rail 9. The back-and-forth 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; both the first copper block 1 and the second copper block 10 are made of copper, which has good conductivity. The first copper block 1 and the second copper block 10 are connected to the slider 8 and the stainless steel base 5 respectively through the first zirconia ceramic block 7 and the second zirconia ceramic block 4, to achieve 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 58mm in length, 34mm in width, and 16mm in height. The dimensions of the graphite sleeve are 16mm in outer diameter, 4mm in inner diameter, and 18mm in length. The dimensions of the long graphite tube 6 are 4mm in outer diameter, 2mm in inner diameter, and 93mm in length. The end of the long graphite tube 6 has a 1mm hole, and the middle protrusion is 10mm long and 1mm thick.

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

[0044] The annular electrode is made of stainless steel; the annular electrode is divided into an inner annular electrode 20 and an outer annular electrode 21; two sets of outer annular electrodes 21 are provided, and the inner annular electrodes 20 are provided between the two sets of outer annular electrodes 21; the length of both sets of outer annular electrodes 21 is 14mm, one set of outer annular electrodes 21 has an inner diameter of 20mm and an outer diameter of 22mm, and the other set of outer annular electrodes 21 has an inner diameter of 26mm and an outer diameter of 28mm; the inner annular electrode has an inner diameter of 12mm, an outer diameter of 14mm, and a length of 14mm.

[0045] The inner annular electrode has several first through holes arranged in five rings, with 16 first through holes in each ring. The diameter of each first through hole is 2 mm. The outer annular electrode 21 has two second through holes at both ends, each with a diameter of 4 mm. These second through holes facilitate the connection of wires to the inner and outer annular electrodes 20 and 21. When used together, the inner and outer annular electrodes 20 and 21 can optimize the electric field distribution and achieve better photoionization effects by changing the distance between them.

[0046] The two-stage sampling cones provided in this embodiment are a primary sampling cone 18 and a secondary sampling cone 19, with a gap between them. The primary sampling cone 18 has a 0.4mm conical hole, and the secondary sampling cone 19 has a 1mm conical hole. The gap between the primary sampling cone 18 and the secondary sampling cone 19 is 15mm. 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. Each quadrupole electrode 15 is a cylindrical stainless steel electrode with a diameter of 9 mm and a length of 56 mm. A PEEK sleeve 16 is nested around each quadrupole electrode 15, and the electrode is fixed to the mass spectrometer chamber by a stainless steel quadrupole base 17.

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

[0049] In this embodiment, an in-situ pyrolysis device using a glow discharge photoionization source is used. The pyrolysis reactants enter the long graphite tube 6 through the zirconia ceramic tube 13. 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, generating high temperature for the pyrolysis reaction under a low vacuum of 0.7 kPa. The fullerenes and their intermediate products generated after pyrolysis are ionized by the glow discharge photoionization device. The specific working principle of the glow discharge photoionization device is as follows: 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 the high electric field, forming plasma between the outer annular electrode 21 and the inner annular electrode 20. Under the action of the electric field, positive ions are accelerated and pass through the first through-hole on the inner annular electrode 20, bombarding the target sample molecules passing through, thereby achieving the ionization of the high-temperature pyrolysis products. The ionized product molecules pass sequentially through the primary sampling cone 18 and the secondary sampling cone 19, and under the guidance of the radio frequency electric field and the DC electric field applied by the quadrupole electrode 15, they reach the time-of-flight mass analyzer, realizing in-situ mass spectrometry analysis of the high-temperature pyrolysis products.

[0050] The in-situ pyrolysis device using a glow discharge photoionization source provided in this embodiment has the following advantages:

[0051] 1. By adopting the glow discharge photoionization source technology, the problem of excessively high ion energy and the generation of more ion fragments, which leads to difficulties in mass spectrum analysis, as in traditional EI, is avoided, and the problem of low PI ionization efficiency is also solved.

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

[0053] 3. By employing a mass spectrometry technique that involves ionization before sampling, the fullerenes and their intermediates produced after high-temperature pyrolysis can avoid molecular collisions and cooling during transport in a buffer atmosphere or on the surface of the sampling cone, thus avoiding the loss of material information of reaction intermediates and achieving true in-situ mass spectrometry analysis.

[0054] 4. A two-stage sampling cone is used to achieve vacuum transition. The spacing between the first-stage sampling cone 18 and the second-stage sampling cone 19 satisfies the Mach disk distribution, which can form an ultrasonic molecular beam with good directionality and reduce background interference.

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

[0056] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. An in-situ pyrolysis apparatus employing a glow discharge photoionization source, characterized in that: It includes a high-temperature pyrolysis device, a glow discharge photoionization device, a two-stage sampling cone, a quadrupole device, and a time-of-flight mass analyzer; The pyrolysis reactants produce fullerenes and their intermediate products through the high-temperature pyrolysis device. The product molecules are then ionized by the glow discharge photoionization device. The ionized ions pass through the two-stage sampling cone and, guided by the radio frequency electric field and DC electric field of the quadrupole device, reach the time-of-flight mass analyzer for in-situ mass spectrometry analysis. The high-temperature pyrolysis device includes a first copper block, a second copper block, a graphite sleeve, and a long graphite tube; the graphite sleeve is respectively embedded at one end of the first copper block and the second copper block, and the graphite sleeve is fitted onto the long graphite tube; The glow discharge photoionization device includes a first electrode fixing cylinder, a second electrode fixing cylinder, and an annular electrode; both the first electrode fixing cylinder and the second electrode fixing cylinder are provided with grooves, which are 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 gap between the primary sampling cone and the secondary sampling cone; The quadrupole device includes four quadrupole electrodes that are parallel to each other and symmetrically placed. The in-situ pyrolysis device also includes 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, and the first copper block is connected to the guide rail via a slider. The first copper block is movable along the guide rail. The annular electrode is made of stainless steel; the annular electrode is divided into an inner annular electrode and an outer annular electrode. Two sets of outer annular electrodes are provided, and the inner annular electrode is provided between the two sets of outer annular electrodes; the inner annular electrode is provided with a plurality of first through holes, and the two ends of the outer annular electrode are provided with second through holes.

2. The in-situ pyrolysis device using a glow discharge photoionization 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; both the first copper block and the second copper block are made of copper.

3. The in-situ pyrolysis device using a glow discharge photoionization source according to claim 1, characterized in that: The sample inlet end of the long graphite tube is connected to a 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.

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

5. The in-situ pyrolysis device using a glow discharge photoionization source according to claim 1, characterized in that: Both sets of outer annular electrodes are 14 mm in length. One set of outer annular electrodes has an inner diameter of 20 mm and an outer diameter of 22 mm, while the other set has an inner diameter of 26 mm and an outer diameter of 28 mm. The inner annular electrode has an inner diameter of 12 mm, an outer diameter of 14 mm, and a length of 14 mm.

6. The in-situ pyrolysis device using a glow discharge photoionization source according to claim 1, characterized in that: The primary sampling cone has a 0.4mm conical hole, and the secondary sampling cone has a 1mm conical hole; the distance between the primary and secondary sampling cones is 15mm.

7. The in-situ pyrolysis device using a glow discharge photoionization 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. The quadrupole electrode is nested with a sleeve made of PEEK material.

8. The in-situ pyrolysis apparatus using a glow discharge photoionization source according to claim 7, characterized in that: Of the four quadrupole electrodes, two opposite quadrupole electrodes form a group; adjacent quadrupole electrodes are applied with an RF voltage with a 180° phase difference and the same DC voltage.

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