Purification method and purification system of molybdenum pentachloride

Abstract

The invention discloses a purification method and a purification system of molybdenum pentachloride, and belongs to the technical field of purification of molybdenum pentachloride. The solid raw materials are placed at the bottom of a sublimation tube, and the sublimation tube is vacuumized to be not higher than 1 mBar. Adjusting the temperature of the heater and the condensation finger in the sublimation pipe, so that the low-sublimation-point impurities in the solid raw material are sublimated and desublimated in sequence and are attached to the condensation finger on the lower layer, and removing part of the first impurities in advance. Then the temperature is adjusted again, so that molybdenum pentachloride in the solid raw material is sublimated and desublimated in sequence and is attached to the condensation finger on the upper layer, and second impurities in the solid raw material are left at the bottom of the sublimation tube. And the circulation is carried out, the temperature of the condensation finger is adjusted step by step, and a high-purity molybdenum pentachloride product is obtained at the condensation finger on the upper layer.

Description

Technical Field

[0001] This application relates to the field of molybdenum pentachloride purification technology, and more specifically, to a purification method and purification system for molybdenum pentachloride. Background Technology

[0002] Molybdenum pentachloride (MoCl5), as an important inorganic compound, has irreplaceable application value in the fields of electronics, chemical catalysis, and materials science. Its unique physicochemical properties (such as high melting point, strong oxidizing power, and easy sublimation) make it a key raw material for the preparation of high-purity molybdenum powder, molybdenum-based thin films, and organometallic compounds. Especially in the fields of semiconductor manufacturing, integrated circuits, and sensors, the purity of electronic-grade molybdenum pentachloride directly determines the performance and reliability of the end products.

[0003] Currently, the main purification methods for molybdenum pentachloride include distillation and solvent recrystallization. Distillation utilizes the boiling point difference between molybdenum pentachloride (boiling point approximately 268℃) and impurities (such as FeCl3, boiling point approximately 315℃). Molybdenum pentachloride is vaporized by heating above its boiling point and then collected by condensation. Solvent recrystallization involves dissolving industrial-grade molybdenum pentachloride in inert organic solvents such as anhydrous carbon tetrachloride or chloroform. After filtering to remove insoluble impurities, crystals are precipitated by evaporating the solvent.

[0004] However, the above methods often have the following key problems in practical applications, making it difficult to meet the requirements for the preparation of ultrapure molybdenum pentachloride: (1) Low purity: Distillation requires heating to above 268°C (boiling point of molybdenum pentachloride). At high temperatures, some impurities (such as AlCl3, boiling point 180°C) are easily azeotropic with molybdenum pentachloride vapor, making it difficult for the product purity to exceed 99.8%. Solvent recrystallization method easily introduces solvent residue (such as carbon tetrachloride), and some soluble impurities (such as trace amounts of NiCl2) cannot be removed by filtration, resulting in limited improvement in purity.

[0005] (2) Low product yield: Molybdenum pentachloride is prone to slight decomposition at high temperature during distillation (generating MoCl3 and Cl2), resulting in yield loss.

[0006] (3) Poor operational safety and pollution risk: The halogenated hydrocarbon solvents used in the solvent recrystallization method are toxic, easily volatilized and pollute the environment, and the operation process requires strict explosion prevention, resulting in low safety.

[0007] Therefore, it is necessary to provide a new purification method to prepare high-purity molybdenum pentachloride. Summary of the Invention

[0008] In view of the above-mentioned shortcomings, this application provides a method and system for purifying molybdenum pentachloride to improve the purity of molybdenum pentachloride.

[0009] This application is implemented as follows: In a first aspect, an example of this application provides a method for purifying molybdenum pentachloride, comprising: The solid feedstock is placed at the bottom of the sublimation tube, and the tube is evacuated to a pressure not exceeding 1 mBar. The solid feedstock contains molybdenum pentachloride, a first impurity with a sublimation point lower than that of molybdenum pentachloride, and a second impurity with a sublimation point higher than that of molybdenum pentachloride. A heater is installed at the bottom of the sublimation tube. Multiple condensation fingers are spaced apart along the tube from bottom to top.

[0010] The temperatures of the heater and the condenser are adjusted so that the first impurity in the solid raw material undergoes sequential sublimation and deposition, adhering to the condenser finger of the next layer, thus partially removing the first impurity. Then, the temperature is adjusted again so that molybdenum pentachloride in the solid raw material undergoes sequential sublimation and deposition, adhering to the condenser finger of the previous layer, while the second impurity remains at the bottom of the sublimation tube. This cycle is repeated, adjusting the temperature of the condenser finger at each stage, until molybdenum pentachloride product is obtained at the upper condenser finger.

[0011] In the above-described process, during the purification of molybdenum pentachloride, the sublimation tube is evacuated to a vacuum level not exceeding 1 mBar. Utilizing the difference in sublimation points between the target product and impurities under vacuum, segmented temperature control directly locks the sublimation range of a single substance. Low-sublimation-point impurities are pre-removed, while high-sublimation-point impurities are retained as residue, preventing co-sublimation of impurities and the target product, significantly reducing residue and improving purity. Furthermore, in a vacuum environment, not only can the sublimation and deposition purification of molybdenum pentachloride be carried out at lower temperatures, improving purification efficiency, but the probability of melting and decomposition of molybdenum pentachloride during purification is also reduced, thereby improving product collection and purification efficiency. The purification process does not require the use of toxic solvents, improving safety. The entire sublimation-deposition purification process is carried out within the same sublimation tube, allowing for continuous operation and mitigating the problems of cross-contamination and low production efficiency caused by frequent product transfers.

[0012] In conjunction with the first aspect, in an optional embodiment of this application, at least a first condensation finger, a second condensation finger, a third condensation finger, and a fourth condensation finger are provided at intervals inside the sublimation tube.

[0013] The temperatures of the heater and the first condenser finger are adjusted to cause the first impurity in the solid raw material to sublimate and condense sequentially, adhering to the first condenser finger. Then, the temperatures of the heater, the first condenser finger, and the second condenser finger are adjusted to cause the molybdenum pentachloride in the solid raw material to sublimate and condense sequentially, adhering to the second condenser finger. Following the method described above, the temperatures of the second and third condensing fingers are adjusted so that the first impurity remaining at the second condensing finger undergoes sequential sublimation and deposition, adhering to the third condensing finger. Then, the temperatures of the second, third, and fourth condensing fingers are adjusted so that molybdenum pentachloride at the second condensing finger undergoes sequential sublimation and deposition, adhering to the fourth condensing finger. This cycle is repeated.

[0014] In the above process, when purifying molybdenum pentachloride, the temperature of the heater and the first condenser finger is first adjusted so that low-sublimation-point impurities in the solid raw material can pre-sublimate and condense, adhering to the first condenser finger, thus achieving pre-separation of the first impurity. Then, the temperatures of the heater, the first condenser finger, and the second condenser finger are adjusted to sublimate the molybdenum pentachloride in the solid raw material, preventing liquefaction. The sublimated molybdenum pentachloride gas is guided to the second condenser finger, where it directly condenses and adheres. Non-volatile impurities and high-sublimation-point impurities in the solid raw material remain at the bottom of the sublimation tube, achieving preliminary purification of molybdenum pentachloride. At the second condenser finger, some first or second impurities inevitably remain (possibly carried by the gas phase). To further purify, the temperatures of the second and third condenser fingers are adjusted again to separate the first impurities to the third condenser finger, removing them again. Then, the temperatures of the second, third, and fourth condensation fingers are adjusted to sublimate and condense molybdenum pentachloride to the fourth condensation finger, while the second impurity remains at the second condensation finger, thus achieving the purification of molybdenum pentachloride step by step.

[0015] In conjunction with the first aspect, in an optional embodiment of this application, the heater is adjusted to a first temperature and the first condensation finger is adjusted to a second temperature, causing the first impurity to adhere to the first condensation finger. Then, the heater is adjusted to a third temperature, the first condensation finger to a fourth temperature, and the second condensation finger to the second temperature, causing molybdenum pentachloride to adhere to the second condensation finger, and the temperature is controlled until the solid raw material at the bottom of the sublimation tube no longer decreases.

[0016] Following the method described above, adjust the second condensation finger to the first temperature and the third condensation finger to the second temperature, causing the first impurity remaining at the second condensation finger to adhere to the third condensation finger. Then adjust the second condensation finger to the third temperature, the third condensation finger to the fourth temperature, and the fourth condensation finger to the second temperature, causing molybdenum pentachloride at the second condensation finger to adhere to the fourth condensation finger. Repeat this cycle.

[0017] The third temperature is the sublimation temperature of molybdenum pentachloride, the first temperature is lower than the third temperature, the second temperature is lower than the deposition temperature of the first impurity, and the fourth temperature is between the first and second temperatures.

[0018] In conjunction with the first aspect, in the optional embodiments of this application, the first temperature is 55~80℃, the second temperature is 15~20℃, the third temperature is 85~110℃, and the fourth temperature is 40~50℃.

[0019] In the above process, when purifying molybdenum pentachloride, the heater temperature is first adjusted to 55-80℃ and the first condenser temperature to 15-20℃. This allows low-sublimation-point impurities in the solid raw material to pre-sublimate and flow to the first condenser, where they directly sublimate at the condensation temperature of the first condenser and adhere to its surface, achieving pre-separation of the first impurities. Then, the heater temperature is adjusted to 85-110℃, the first condenser temperature to 40-50℃, and the second condenser temperature to 15-20℃. This causes the molybdenum pentachloride in the solid raw material to sublimate, preventing liquefaction. Because the temperature of the second condenser is lower than that of the first condenser, the sublimated molybdenum pentachloride gas is guided to the second condenser, where it directly sublimates and adheres. Meanwhile, non-volatile impurities and high-sublimation-point impurities in the solid raw material remain at the bottom of the sublimation tube, achieving preliminary purification of molybdenum pentachloride. The temperature of the second condensation finger is adjusted again to 55-80℃ and the temperature of the third condensation finger to 15-20℃, causing the first impurity to sublimate and condense to the third condensation finger, thus removing the first impurity. Then, the temperature of the second condensation finger is adjusted to 85-110℃, the temperature of the third condensation finger to 40-50℃, and the temperature of the fourth condensation finger to 15-20℃, causing molybdenum pentachloride to sublimate and condense to the fourth condensation finger, while the second impurity remains at the second condensation finger. This stepwise purification of molybdenum pentachloride is achieved. During the purification process, gradient temperature pre-drying is possible, raw material melting is avoided, the isothermal sublimation process is stable, and the product yield is high.

[0020] In conjunction with the first aspect, in an optional embodiment of this application, at least six condensation fingers are provided at intervals inside the sublimation tube.

[0021] In the above process, at least six condensation fingers are set at intervals inside the sublimation tube, and at least three rounds of sublimation-condensation purification are carried out to obtain molybdenum pentachloride products with higher purity.

[0022] In conjunction with the first aspect, in an optional embodiment of this application, a heat insulation plate is provided on the bottom side of each condensation finger.

[0023] In the above implementation process, a heat insulation plate is installed on the bottom side of each condensation finger, which can guide the sublimated gas phase to the top side of the condensation finger for condensation. This reduces the probability that the sublimation adhering to the condensation finger will fall off to the condensation finger below during subsequent purification, thereby improving purification efficiency.

[0024] In conjunction with the first aspect, in an optional embodiment of this application, multiple condensing fingers are staggered inside the sublimation tube, dividing the internal space of the sublimation tube into S-shaped gas channels.

[0025] Optionally, the solid raw material is industrial-grade molybdenum pentachloride.

[0026] In the above process, multiple condensation fingers are staggered inside the sublimation tube, dividing the internal space of the sublimation tube into S-shaped gas channels. During the purification process, the gaseous substance formed by sublimation can flow from the gaps between the condensation fingers to the upper condensation finger, increasing the contact time between the gaseous substance and the target condensation finger, promoting the sublimation and adhesion of the gaseous substance to the target condensation finger, and improving the purification efficiency and purity.

[0027] In conjunction with the first aspect, in an optional embodiment of this application, the purification method further includes a pretreatment step before placing the solid raw material into the sublimation tube: Rinse the sublimation tube repeatedly with 3-5% nitric acid and deionized water at least three times, then air dry; the sublimation tube is made of polytetrafluoroethylene.

[0028] In the above process, before purifying the solid raw material, it is repeatedly rinsed with 3-5% nitric acid, deionized water, 3-5% nitric acid, and deionized water in sequence. This reduces the impact of impurities in the sublimation tube itself on the purity of molybdenum pentachloride. Using a sublimation tube made of polytetrafluoroethylene (PTFE) further reduces the probability of introducing metallic impurities.

[0029] In a second aspect, an example of this application provides a purification system for implementing the purification method provided in the first aspect, comprising a sublimation tube and a vacuum pump. The sublimation tube includes a tube body and a plurality of condensing fingers. Along the axial direction of the tube body, a plurality of connection ports are spaced apart on the body wall of the tube body, and the plurality of condensing fingers extend into the interior of the tube body through the plurality of connection ports in a corresponding manner and are detachably and sealingly connected to the tube body; a heater is also provided at the bottom of the tube body. A feed inlet is also provided on the side wall of the tube body. The vacuum pump is configured to evacuate the tube body.

[0030] In the above-described purification process, when purifying molybdenum pentachloride using the aforementioned purification system, each condensing finger is sealed and connected to the tube body through its corresponding connector. The solid raw material containing molybdenum pentachloride is loaded into the tube body through the inlet, and then the tube body is evacuated to a vacuum level not exceeding 1 mBar. The temperature of the heater at the bottom of the sublimation tube and the condensing fingers inside the sublimation tube are then adjusted so that low-sublimation-point impurities, molybdenum pentachloride, and high-sublimation-point impurities in the solid raw material can adhere to different condensing fingers or the bottom of the sublimation tube. The solid raw material is purified through sublimation-condensation to obtain a high-purity molybdenum pentachloride product. After purification, each condensing finger can be withdrawn from its corresponding connector, and the dark green needle-like crystals adhering to the uppermost condensing finger can be scraped off to obtain the molybdenum pentachloride product.

[0031] By directly setting multiple condensation fingers at intervals inside the sublimation tube, the entire sublimation-condensation purification process can be carried out in the same sublimation tube, allowing for continuous operation and improving the problems of cross-contamination and low production efficiency caused by frequent product transfer.

[0032] In conjunction with the second aspect, in an optional embodiment of this application, the condenser includes a condenser tube and a sealing sleeve fitted onto the outer wall of one end of the condenser tube. The condenser tube is detachably and sealed to the connection port via the sealing sleeve. The condenser tube has an inlet and an outlet. The inlet is configured to deliver condensate into the condenser tube, and the outlet is configured to discharge the condensate from the condenser tube.

[0033] In the above process, a sealing sleeve is connected to the outer wall of one end of the condenser tube. The other end of the condenser tube is then inserted into the tube body and sealed to the tube body through the sealing fit between the sleeve and the connection port. The condenser tube is equipped with an inlet and an outlet. When the temperature of the condensing finger needs to be adjusted, a working medium of the corresponding temperature (e.g., water at different temperatures) can be introduced into the condenser tube through the inlet, and the working medium after heat exchange can be discharged through the outlet. This maintains a relatively constant temperature at the condenser tube, allowing impurities or molybdenum pentachloride gas to sublimate and adhere to the corresponding condensing finger under its cooling effect, thus achieving the purification of molybdenum pentachloride.

[0034] In conjunction with the second aspect, in an optional embodiment of this application, a heat insulation plate is provided on the bottom side of each condensation finger.

[0035] In the above implementation process, a heat insulation plate is installed on the bottom side of each condensation finger. When the condensation finger is working, the temperature on the top side of the condensation finger is lower than the temperature on the bottom side. When the sublimated gaseous substances flow to the condensation finger, these gaseous substances tend to adhere to the top side of the condensation finger. In the continuous sublimation-condensation purification process, the falling of these separated condensed substances from the upper condensation finger to the lower condensation finger can be reduced, thereby improving the purification efficiency.

[0036] In conjunction with the second aspect, in an optional embodiment of this application, multiple condensing fingers are staggered inside the tube body, dividing the internal space of the tube body to form an S-shaped gas channel.

[0037] In the above process, multiple condensation fingers are arranged at intervals inside the tube. The multiple condensation fingers are arranged in an alternating manner, dividing the internal space of the tube into a gas channel similar to an S-shape. During the purification process, the gaseous substance formed by sublimation can flow from the gap between the condensation fingers to the upper layer of condensation fingers, increasing the contact time between the gaseous substance and the condensation fingers, promoting the sublimation and adhesion of the gaseous substance to the corresponding condensation fingers, and improving the purification efficiency and purity. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0039] Figure 1 This is a first schematic diagram of a purification system provided in an embodiment of this application; Figure 2 This is a second schematic diagram of a purification system provided in an embodiment of this application.

[0040] Icons: 100-Purification system; 1-Sublimation tube; 11-Tube body; 111-Connection port; 112-Inlet; 113-Gas port; 12-Condensation finger; 121-Condensation tube; 122-Liquid inlet; 123-Liquid outlet; 124-Sealing sleeve; 125-Heat insulation plate; 126-First condensation finger; 127-Second condensation finger; 128-Third condensation finger; 129-Fourth condensation finger; 13-Heater; 2-Vacuum pump. Detailed Implementation

[0041] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0042] Molybdenum pentachloride (MoCl5), as an important inorganic compound, has irreplaceable application value in the fields of electronics, chemical catalysis, and materials science. Currently, the main purification methods for molybdenum pentachloride include distillation and solvent recrystallization.

[0043] However, the above method has the following key problems in practical applications, making it difficult to meet the requirements for the preparation of ultrapure molybdenum pentachloride: (1) Low purity: The distillation method mainly utilizes the boiling point difference between molybdenum pentachloride (boiling point about 268℃) and impurities (such as FeCl3, boiling point about 315℃). Molybdenum pentachloride is vaporized by heating to above the boiling point and then collected by condensation. The distillation method requires heating to above 268℃ (the boiling point of molybdenum pentachloride). At high temperatures, some impurities (such as AlCl3, boiling point 180℃) are easily azeotropic with the molybdenum pentachloride vapor, making it difficult for the product purity to exceed 99.8%. The solvent recrystallization method mainly uses inert organic solvents such as anhydrous carbon tetrachloride and chloroform to dissolve industrial-grade molybdenum pentachloride. After filtering to remove insoluble impurities, crystals are precipitated by evaporating the solvent. The solvent recrystallization method easily introduces solvent residues (such as carbon tetrachloride), and some soluble impurities (such as trace amounts of NiCl2) cannot be removed by filtration, resulting in limited improvement in purity.

[0044] (2) Low product yield: Molybdenum pentachloride is prone to slight decomposition at high temperature during distillation (generating MoCl3 and Cl2), resulting in yield loss.

[0045] (3) Poor operational safety and pollution risk: The halogenated hydrocarbon solvents used in the solvent recrystallization method are toxic, easily volatile, and pollute the environment. Furthermore, the operation requires strict explosion-proof measures, resulting in low safety. The decomposition products of the distillation method are also easily volatile and pollute the environment.

[0046] Based on this, embodiments of this application provide a method and system for purifying molybdenum pentachloride. The purification process does not require the use of toxic organic solvents, making it safer and improving product purity and yield. To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0047] The purification method provided in this application includes: S1. Place the solid raw material at the bottom of the sublimation tube and evacuate the sublimation tube to a vacuum level not exceeding 1 mBar. The solid raw material contains molybdenum pentachloride, a first impurity with a sublimation point lower than that of molybdenum pentachloride, and a second impurity with a sublimation point higher than that of molybdenum pentachloride. A heater is installed at the bottom of the sublimation tube. Multiple condensation fingers are spaced apart along the sublimation tube from bottom to top.

[0048] S2. Adjust the temperature of the heater and the condenser finger so that the first impurity in the solid raw material sublimates and condenses sequentially, adhering to the lower condenser finger, thus partially removing the first impurity. Then, adjust the temperature again so that the molybdenum pentachloride in the solid raw material sublimates and condenses sequentially, adhering to the upper condenser finger, while the second impurity in the solid raw material remains at the bottom of the sublimation tube. Repeat this cycle, adjusting the temperature of the condenser fingers step by step, until the molybdenum pentachloride product is obtained at the highest condenser finger.

[0049] Sublimation is a phase transition process in which a substance changes directly from a solid state to a gaseous state without passing through a liquid state; the reverse process is called deposition. In step S1, the sublimation point refers to the critical temperature at which the solid state changes directly to a gaseous state without passing through a liquid state under the given pressure.

[0050] A heater is installed at the bottom of the sublimation tube. After the solid raw material is placed inside the sublimation tube, it can be heated by the heater. Along the sublimation tube from low to high, multiple condensation fingers are arranged at intervals inside the sublimation tube. By adjusting the temperature of the condensation fingers inside the sublimation tube, the sublimated gaseous substances can be selectively guided to condense at the target condensation point and then adhere to the surface of the condensation fingers.

[0051] In step S2, by adjusting the temperature of the condenser finger and the heater, the solid raw material can be preheated to a temperature below the sublimation point of molybdenum pentachloride. At this temperature, molybdenum pentachloride and the second impurity with a high sublimation point will not melt or sublimate, while the first impurity with a low sublimation point will sublimate into a gaseous phase and separate from the solid raw material. The first impurity gas flows upward to the condenser finger, where it condenses at the condensation temperature of the condenser finger and adheres to the first layer of the condenser finger, thus achieving the pre-removal of the first impurity. Then, the solid raw material is heated to the sublimation point temperature of molybdenum pentachloride, causing it to sublimate. The second impurity with a high sublimation point will remain at the bottom of the sublimation tube. The temperature of the condenser finger is adjusted so that the molybdenum pentachloride gas sublimates at another condenser finger, selectively adhering the first impurity, molybdenum pentachloride, and the second impurity to different condenser fingers and sublimation tubes, achieving the purification of molybdenum pentachloride. By adjusting the temperature of each condenser finger step by step according to the above steps, the first and second impurities in molybdenum pentachloride are separated, and a high-purity molybdenum pentachloride product is obtained at the upper condenser finger.

[0052] This method employs sublimation-deposition purification under vacuum conditions. Utilizing the difference in sublimation points between the target product and impurities under vacuum, segmented temperature control directly locks the sublimation range of a single substance. Low-sublimation-point impurities are pre-removed, while high-sublimation-point impurities are retained as residue, preventing co-sublimation of impurities and the target product and significantly reducing residue. Furthermore, the vacuum environment allows for sublimation and deposition purification of molybdenum pentachloride at lower temperatures, increasing the sublimation rate and reducing the probability of decomposition during purification, thus improving product collection and purification efficiency. The purification process eliminates the need for toxic solvents, enhancing safety. The entire sublimation-deposition purification process is conducted within a single sublimation tube, enabling continuous operation and mitigating cross-contamination and low production efficiency caused by frequent product transfers.

[0053] To facilitate the implementation of the above purification operations, this application provides a purification system 100. Please refer to [link / reference]. Figure 1 The system includes a sublimation tube 1 and a vacuum pump 2. The sublimation tube 1 includes a tube body 11 and multiple condensing fingers 12. Along the axial direction of the tube body 11, multiple connection ports 111 are spaced apart on the wall of the tube body 11. The multiple condensing fingers 12 extend into the interior of the tube body 11 through the multiple connection ports 111 and are detachably and sealingly connected to the tube body 11. A heater 13 is also provided at the bottom of the tube body 11. A feed port 112 is also provided on the side wall of the tube body 11. The vacuum pump 2 is equipped to evacuate the tube body 11.

[0054] During purification, each condenser finger 12 can be inserted into the tube body 11 through the connection port 111, and the solid raw material is placed at the bottom of the tube body 11. The solid raw material is heated by the heater 13, and the temperature of the condenser finger 12 is adjusted by the working fluid in the condenser finger 12.

[0055] In some embodiments, please continue reading Figure 1 The condenser 12 includes a condenser tube 121 and a sealing sleeve 124 fitted onto the outer wall of one end of the condenser tube 121. The condenser tube 121 is detachably and sealed to the connection port 111 via the sealing sleeve 124. The condenser tube 121 has an inlet 122 and an outlet 123. The inlet 122 is configured to supply condensate into the condenser tube 121. The outlet 123 is configured to discharge the condensate from the condenser tube 121. The temperature of each condenser 12 can be adjusted by injecting working fluids of different temperatures into each condenser tube 121.

[0056] This application does not limit the specific shape of the condenser tube 121. As an example, the condenser tube 121 can be a U-shaped tube, with the liquid inlet 122 and liquid outlet 123 of the U-shaped tube located on one side of the sealing sleeve 124. When the sealing sleeve 124 is sealed and connected to the connection port 111 of the tube body 11, the liquid inlet 122 and liquid outlet 123 of the U-shaped tube are located outside the tube body 11. Alternatively, as an example, the condenser tube 121 can be a double-layered tube, having an inner tube and an outer tube. One end of the inner tube extends into the outer tube and is sealed and connected to the outer tube. The sealing sleeve 124 is fitted onto the outer wall of the outer tube. The end of the inner tube extending out of the outer tube has a liquid inlet 122, and the outer tube has a liquid outlet 123. When the sealing sleeve 124 is sealed and connected to the connection port of the tube body, the liquid inlet 122 and liquid outlet 123 are located outside the tube body 11.

[0057] The condenser tube 121 can be flat or cylindrical, and this application does not impose any limitation on its shape. As an example, in order to increase the attachment area of ​​the condenser tube 121, its shape can be set to flat.

[0058] Furthermore, since multiple condensation fingers 12 are spaced apart along the axial direction of the tube body 11, and each condensation finger 12 is used to condense and adhere to different components, in order to prevent the sublimation adhering to the previous condensation finger 12 from falling to the next condensation finger 12 and causing the components to mix again, in some embodiments, please refer to... Figure 2 A heat insulation plate 125 can be installed on the bottom side of the condenser tube 121. During the operation of the condenser finger 12, after a working liquid of a certain temperature is introduced into the condenser tube 121, the temperature of the top side of the condenser tube 121 will change, rising or falling to the target temperature, while the temperature of the bottom side of the condenser tube 121 remains constant. Therefore, when the sublimated gaseous substances flow to the condenser finger 12, because the temperature of the top side of the condenser tube 121 is lower, these gaseous substances tend to sublimate on the top side of the condenser tube 121 and adhere to the top side of the condenser tube 121. With the support of the condenser tube 121 and the heat insulation plate 125, the sublimated substances adhering to the top side of the condenser tube 121 are not easily dropped to the condenser finger 12 below.

[0059] This application does not limit the specific arrangement of the heat insulation plate 125. As an example, the heat insulation plate 125 can cover the bottom outer wall of the condenser tube 121. Alternatively, along the direction of gravity, the projection of the heat insulation plate 125 is larger than the projection of the condenser tube 121, and the heat insulation plate 125 is located at a certain distance below the condenser tube 121. Even if the condensate adhering to the outer wall of the condenser tube 121 falls downwards, it will fall onto the heat insulation plate 125.

[0060] This application does not limit the specific material of the insulation board 125; conventional insulation materials can be selected.

[0061] It is understood that when the condensing fingers 12 are spaced apart within the tube body 11, channels for gas to pass through can be formed between the condensing fingers 12, allowing gas to flow from bottom to top to different condensing fingers 12. This application does not limit the specific arrangement of each condensing finger 12 within the tube body 11; in some embodiments, please refer to [further details]. Figure 1 and Figure 2 Multiple condensing fingers 12 are staggered inside the tube body 11, dividing the internal space of the tube body 11 into S-shaped gas channels.

[0062] like Figure 2 As shown, in two adjacent condensing fingers 12, the two sealing sleeves 124 are sealed to the connection ports 111 at both ends of the tube body 11 in the radial direction. The condensing fingers 12 are arranged laterally, and there is a gap between the end of each condensing finger 12 away from the sealing sleeve 124 and the inner wall of the tube body 11.

[0063] This application does not limit the specific number of condensation fingers 12 inside the tube. In some embodiments, at least four condensation fingers are provided at intervals inside the tube 11. For ease of description, they are referred to as the first condensation finger 126, the second condensation finger 127, the third condensation finger 128, and the fourth condensation finger 129, respectively.

[0064] In some embodiments, at least six condensation fingers 12 are provided at intervals inside the tube body 11.

[0065] This application does not limit the specific type of heater 13, as long as it can achieve heating. As an example, heater 13 can be a resistance wire heater. Alternatively, it can be a support platform made of a thermally conductive material, with working liquids of different temperatures flowing through its interior, on which a solid sample can be placed. The solid raw material is then heated by the working liquid.

[0066] This application does not limit the specific location of the feed inlet 112, as long as it allows the solid raw material to be placed at the bottom heater 13 of the tube body 11. As an example, the feed inlet 112 is located on the side wall of the tube body 11 near the bottom, and a removable sealing plug is provided at the feed inlet 112. After the solid raw material is loaded, the feed inlet 112 of the tube body 11 can be sealed by the sealing plug.

[0067] For further information, please continue to refer to [link / reference]. Figure 1 and Figure 2 To facilitate vacuuming of the tube 11, an air port 113 is provided at the top of the tube 11. The vacuum pump 2 is connected to the air port 113 through a pipeline.

[0068] Furthermore, in some embodiments, the aforementioned pipeline includes a main pipe and two branch pipes connected to the main pipe, each branch pipe being equipped with a switch valve. One branch pipe is connected to the vacuum pump 2, and the other branch pipe is connected to an inert gas conveyor. Before purification, the sublimation tube 1 can be evacuated using the vacuum pump 2, and high-purity inert gas can be introduced into the sublimation tube 1 through the inert gas conveyor to displace the gas inside the sublimation tube 1. After loading the solid raw material into the sublimation tube 1, the vacuum pump 2 is used to evacuate the sublimation tube 1 to a level not exceeding 1 mBar, and the sublimation-condensation purification of the solid raw material is carried out under vacuum conditions, improving purification efficiency and product purity.

[0069] To reduce the impact of metallic impurities in the pipeline on the purity of the molybdenum pentachloride product, in some embodiments, the pipeline is made of polytetrafluoroethylene (PTFE). Similarly, in some embodiments, the pipe body can also be made of PTFE.

[0070] Furthermore, in order to facilitate the storage of molybdenum pentachloride product, in some embodiments, the purification system is also provided with a product tank (not shown in the figure).

[0071] The purification method of this application will be further described in detail below with reference to the purification system 100 provided in this embodiment.

[0072] In step S1, when purifying the solid raw material, industrial-grade molybdenum pentachloride can be used as the raw material. The purity of industrial-grade molybdenum pentachloride is usually around 99%, and further purification is needed to obtain molybdenum pentachloride products with electronic-grade purity (above 99.99%).

[0073] When purifying solid raw materials, step S2 includes: S21. Adjust the temperature of heater 13 and first condenser 126 so that the first impurity in the solid raw material sublimates and condenses in sequence, and adheres to the first condenser 126.

[0074] S22. Then adjust the temperature of heater 13, first condenser 126 and second condenser 127 so that molybdenum pentachloride in the solid raw material sublimates and condenses in sequence, and adheres to the second condenser 127.

[0075] At the second condensation finger 127, a small amount of the first or second impurity is inevitably carried. Therefore, the condensate at the second condensation finger 127 can undergo another round of sublimation-condensation purification. This includes: S23. Following the above method, adjust the temperature of the second condensation finger 127 and the third condensation finger 128 so that the first impurity remaining at the second condensation finger 127 will sublimate and condense in sequence, and adhere to the third condensation finger 128.

[0076] S24. Then adjust the temperature of the second condensation finger 127, the third condensation finger 128 and the fourth condensation finger 129 so that the molybdenum pentachloride at the second condensation finger 127 sublimates and condenses in sequence, and adheres to the fourth condensation finger 129.

[0077] If more sublimation-condensation purification is required, the temperature of the corresponding condensation finger can be adjusted step by step according to the above steps S23 and S24, and this cycle can be repeated to obtain molybdenum pentachloride product at the highest condensation finger.

[0078] Furthermore, in some embodiments, in step S21, the heater 13 is adjusted to a first temperature and the first condensation finger 126 is adjusted to a second temperature, so that the first impurity adheres to the first condensation finger 126.

[0079] Then, in step S22, the heater 13 is adjusted to the third temperature, the first condensing finger 126 to the fourth temperature, and the second condensing finger 127 to the second temperature, so that molybdenum pentachloride adheres to the second condensing finger 127, and the temperature is controlled until the solid raw material at the bottom of the sublimation tube 1 no longer decreases.

[0080] In step S23, the second condensation index 127 is adjusted to the first temperature and the third condensation index 128 is adjusted to the second temperature, so that the first impurity remaining at the second condensation index 127 is attached to the third condensation index 128.

[0081] Then, in step S24, the second condensation finger 127 is adjusted to the third temperature, the third condensation finger 128 to the fourth temperature, and the fourth condensation finger 129 to the second temperature, so that molybdenum pentachloride at the second condensation finger 127 adheres to the fourth condensation finger 129. This cycle is repeated to obtain the molybdenum pentachloride product at the highest condensation finger.

[0082] The third temperature is the sublimation temperature of molybdenum pentachloride, the first temperature is lower than the third temperature, the second temperature is lower than the deposition temperature of the first impurity, and the fourth temperature is between the first and second temperatures.

[0083] By utilizing the difference in sublimation points between the target product and impurities under vacuum, segmented temperature control directly locks the sublimation range of a single substance. Impurities with low sublimation points are pre-removed, while impurities with high sublimation points are left as residue, thus avoiding co-sublimation of impurities and the target substance, significantly reducing residue and improving product purity.

[0084] As an example, the first temperature is 55~80℃, the second temperature is 15~20℃, the third temperature is 85~110℃, and the fourth temperature is 40~50℃.

[0085] As an example, in step S21, the solid raw material is heated to 55~80℃. Low sublimation point impurities such as aluminum chloride in the solid raw material will sublimate and flow to the first condensation finger 126 at a temperature of 15~20℃. They will sublimate at the first condensation finger 126 and adhere to the surface of the first condensation finger 126. The temperature is controlled for 1~3 hours to achieve the pre-removal of low sublimation point impurities.

[0086] In step S22, the solid raw material is heated to 85-110°C, causing molybdenum pentachloride in the solid raw material to sublimate. Simultaneously, the temperature of the first condenser 126 is controlled at 40-50°C and the temperature of the second condenser 127 at 15-20°C. Since the temperature of the second condenser 127 is lower than that of the first condenser 126, the molybdenum pentachloride gas tends to flow to the second condenser 127 and sublimate there, adhering to the second condenser 127. At this time, the temperature of the first condenser 126 has not reached the sublimation point temperature of the first impurity (55-80°C), so the first impurity at the first condenser 126 will not sublimate and will not re-adhere to the second condenser 127. High-sublimation-point impurities in the solid raw material, such as ferric chloride, will remain at the bottom of the sublimation tube 1 because the heating temperature has not reached their sublimation point. The temperature is controlled until the solid raw material at the bottom of the sublimation tube 1 no longer decreases. This achieves the first round of separation and purification of molybdenum pentachloride.

[0087] To facilitate observation of whether the solid material at the bottom of the sublimation tube 1 has decreased, in some embodiments, the heater 13 can be configured as a heater with a weighing function. The solid material is placed on the heater and weighed. When the weight of the solid material no longer changes, it proves that the molybdenum pentachloride in the solid material has been basically completely sublimated. At this point, step S22 can be ended, and the next round of sublimation-condensation purification can be carried out.

[0088] After steps S21 and S22, molybdenum pentachloride with a purity of 99.9% can be obtained.

[0089] In order to further purify the condensate at the second condensation finger 127, in step S23, the temperature of the second condensation finger 127 is adjusted to 55~80°C and the temperature of the third condensation finger 128 is adjusted to 15~20°C, so that the first impurity remaining at the second condensation finger 127 is attached to the third condensation finger 128.

[0090] Then, in step S24, the second condensation index 127 is adjusted to 85~110°C, the third condensation index 128 to 40~50°C, and the fourth condensation index 129 to 15~20°C, so that molybdenum pentachloride at the second condensation index 127 adheres to the fourth condensation index 129. This cycle is repeated to obtain the molybdenum pentachloride product at the highest condensation index.

[0091] Remove the condenser finger from the tube containing the molybdenum pentachloride product, scrape the product off the condenser finger using a PTFE spoon, and place it in the product container.

[0092] The purification method of this application will be further described in detail below with reference to the embodiments.

[0093] Example 1 This embodiment provides a method for purifying molybdenum pentachloride, utilizing... Figure 1 The purification system shown includes: (1) Purification, sample loading and pretreatment: First, soak the sublimation tubes, product containers, and other equipment in 3% nitric acid for 2 hours, then rinse with deionized water until neutral, then soak again in 3% nitric acid for 2 hours, rinse with deionized water until neutral, and finally air dry in a clean cabinet.

[0094] Operate within a nitrogen glove box. Transfer the product canister, purified sublimation tube, and PTFE tools to the transition chamber. After circulating the process through vacuum and nitrogen at least three times (to replace air), transfer them back into the glove box. Use a PTFE spoon to take 0.5-5g of raw material (industrial-grade molybdenum pentachloride, purity ≥99.6%, containing Fe and Al impurities. Avoid introducing contamination with metal tools), transfer it into the sublimation tube, gently compact it (to prevent blockage of the vapor passage), and seal tightly.

[0095] Assemble the sublimation tube inside the glove box. After removing it from the glove box, connect the high-purity nitrogen cylinder (with drying column) to the vacuum pump. Close the nitrogen valve, turn on the vacuum pump to evacuate the system until the pressure is ≤1 mbar, turn off the vacuum pump and let it stand for 60 minutes. If the pressure increase is ≤1 mbar, the airtightness is qualified; otherwise, reseal all the joints of the tube.

[0096] (2) Heat the solid raw material to 55~80℃, and at the same time control the temperature of the first condensation point to 15~20℃ for 1~3 hours.

[0097] (3) Heat the solid raw material to 85~110℃, while controlling the temperature of the first condensation finger to 40~50℃ and the temperature of the second condensation finger to 15~20℃. When the raw material at the bottom of the sublimation tube no longer decreases and there are basically no new crystals generated on the surface of the second condensation finger, the first round of sublimation is judged to be over.

[0098] (4) Adjust the second condensation index to 55~80℃ and the third condensation index to 15~20℃, and control the temperature for 1~3 hours.

[0099] (5) Adjust the second condensation index to 85~110℃, the third condensation index to 40~50℃, and the fourth condensation index to 15~20℃. When it is observed that the raw material in the second condensation index no longer decreases and there are basically no new crystals generated on the surface of the fourth condensation index, the second round of sublimation is determined to be over.

[0100] (6) Following the above steps, perform seven rounds of sublimation-deposition process to obtain the sublimated sample ①.

[0101] Comparative Example 1 A comparative example provides a method for purifying molybdenum pentachloride, which differs from Example 1 in that: In step (2), the solid raw material is gradually heated to 150°C, while the temperature of the first condensation point is controlled to 15~20°C for 1~3 hours.

[0102] Step (3) is skipped. The glove box is restored to normal pressure inside the sublimation tube, and the first condenser finger is removed and the sublimation material is scraped off. Sublimated sample ② is obtained.

[0103] The samples provided in the above examples and comparative examples, as well as the unpurified raw materials, were sequentially digested with ultrapure HF solution, then diluted to volume with 3% HNO3, and analyzed by ICP-MS for comparison. The test results are shown in Table 1.

[0104] Table 1

[0105] Results analysis: As can be seen from Table 1, the purification method provided in the embodiments of this application, which uses a multi-stage temperature control method of sublimation-deposition for purification, can significantly improve the purity of molybdenum pentachloride products with high efficiency compared to the conventional sublimation process.

[0106] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for purifying molybdenum pentachloride, characterized in that, include: A solid raw material is placed at the bottom of a sublimation tube, and the sublimation tube is evacuated to a level not exceeding 1 mBar. The solid raw material contains molybdenum pentachloride, a first impurity with a sublimation point lower than that of molybdenum pentachloride, and a second impurity with a sublimation point higher than that of molybdenum pentachloride. A heater is provided at the bottom of the sublimation tube. Multiple condensation fingers are arranged at intervals along the sublimation tube from low to high. Adjusting the temperature of the heater and the condenser finger causes the first impurity in the solid raw material to sublimate and condense sequentially, adhering to the condenser finger located in the next layer, thus removing part of the first impurity in advance. Then the temperature is adjusted again to cause the molybdenum pentachloride in the solid raw material to sublimate and condense sequentially, adhering to the condensation finger located on the upper layer, while the second impurity in the solid raw material remains at the bottom of the sublimation tube; this cycle is repeated, and the temperature of the condensation finger is adjusted step by step to obtain the molybdenum pentachloride product at the upper condensation finger.

2. The purification method according to claim 1, characterized in that, The sublimation tube is provided with at least a first condensation finger, a second condensation finger, a third condensation finger, and a fourth condensation finger at intervals; The temperatures of the heater and the first condenser finger are adjusted so that the first impurity in the solid raw material undergoes sublimation and deposition sequentially, adhering to the first condenser finger; then the temperatures of the heater, the first condenser finger, and the second condenser finger are adjusted so that the molybdenum pentachloride in the solid raw material undergoes sublimation and deposition sequentially, adhering to the second condenser finger. Following the above method, the temperatures of the second and third condensers are adjusted so that the first impurity remaining at the second condenser undergoes sublimation and deposition sequentially, adhering to the third condenser; then the temperatures of the second, third, and fourth condensers are adjusted so that molybdenum pentachloride at the second condenser undergoes sublimation and deposition sequentially, adhering to the fourth condenser; this process is repeated.

3. The purification method according to claim 2, characterized in that, Adjust the heater to a first temperature and the first condensation finger to a second temperature so that the first impurity adheres to the first condensation finger; then, adjust the heater to a third temperature, the first condensation finger to a fourth temperature, and the second condensation finger to a second temperature so that the molybdenum pentachloride adheres to the second condensation finger, and control the temperature until the solid raw material at the bottom of the sublimation tube no longer decreases; Following the above method, the second condensation finger is adjusted to the first temperature, and the third condensation finger is adjusted to the second temperature, so that the first impurity remaining at the second condensation finger adheres to the third condensation finger; then the second condensation finger is adjusted to the third temperature, the third condensation finger is adjusted to the fourth temperature, and the fourth condensation finger is adjusted to the second temperature, so that the molybdenum pentachloride at the second condensation finger adheres to the fourth condensation finger; this process is repeated. Wherein, the third temperature is the sublimation temperature of the molybdenum pentachloride, the first temperature is lower than the third temperature, the second temperature is lower than the deposition temperature of the first impurity, and the fourth temperature is between the first temperature and the second temperature.

4. The purification method according to claim 3, characterized in that, The first temperature is 55~80℃, the second temperature is 15~20℃, the third temperature is 85~110℃, and the fourth temperature is 40~50℃.

5. The purification method according to any one of claims 1 to 4, characterized in that, The sublimation tube has at least six condensation fingers spaced apart.

6. The purification method according to claim 1, characterized in that, Each of the condensing fingers is provided with a heat insulation plate on its bottom side.

7. The purification method according to claim 1 or 6, characterized in that, Multiple condensing fingers are staggered inside the sublimation tube, dividing the internal space of the sublimation tube into S-shaped gas channels; Optionally, the solid raw material is industrial-grade molybdenum pentachloride.

8. The purification method according to claim 1, characterized in that, Before placing the solid raw material into the sublimation tube, the purification method further includes a pretreatment step: The sublimation tube is rinsed repeatedly with 3-5% nitric acid and deionized water at least three times, and then dried. The material of the sublimation tube is polytetrafluoroethylene.

9. A purification system for implementing the purification method according to any one of claims 1 to 8, characterized in that, include: A sublimation tube includes a tube body and multiple condensation fingers; along the axial direction of the tube body, multiple connection ports are spaced apart on the body wall of the tube body, and the multiple condensation fingers extend into the interior of the tube body through the multiple connection ports in a corresponding manner and are detachably and sealingly connected to the tube body; a heater is also provided at the bottom of the tube body; and a feed port is also provided on the side wall of the tube body. A vacuum pump is provided for evacuating the tube.

10. The purification system according to claim 9, characterized in that, The condenser includes a condenser tube and a sealing sleeve fitted on the outer wall of one end of the condenser tube. The condenser tube is detachably and sealed to the connection port through the sealing sleeve. The condenser tube has an inlet and an outlet. The inlet is configured to deliver condensate into the condenser tube, and the outlet is configured to discharge the condensate from the condenser tube.

11. The purification system according to claim 10, characterized in that, Each of the condenser tubes is provided with a heat insulation plate on its bottom side.

12. The purification system according to claim 9, characterized in that, Multiple condensing fingers are staggered inside the tube, dividing the internal space of the tube into S-shaped gas channels.

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