A method for rectification purification of diiodosilane

Abstract

The present application relates to diiodosilane synthesis technical field, disclose a kind of rectification purification method of diiodosilane, utilize two-stage rectification system to carry out purification, comprising the following steps: S1, diiodosilane mother liquor is added to first rectification tower, and heating temperature T1 is distilled;S2, diiodosilane steam is heat-exchanged by heat exchanger, and diiodosilane pure product is obtained by condensation;S3, the residual mother liquor in the bottom of first rectification tower lower tower body is distilled by adding second rectification tower, and heating temperature T2;S4, diiodosilane steam generated in the lower tower body of second rectification tower is condensed after heat exchange by preheating mechanism and heat exchanger, and diiodosilane pure product is obtained, and the residual liquid in the bottom of tower body enters recovery tank.By the two-stage rectification system of the present application, diiodosilane is purified, continuous rectification purification of diiodosilane is realized, the yield of diiodosilane is improved, and the preheating mechanism is used to heat-exchange diiodosilane mother liquor and diiodosilane steam, energy consumption is reduced, and the purity of diiodosilane is also improved.

Description

Technical Field

[0001] This invention belongs to the field of diiodosilane synthesis technology, specifically relating to a distillation purification method for diiodosilane. Background Technology

[0002] Diiodosilane (H2SiI2) has a boiling point of 56℃~60℃ and possesses unique physicochemical properties compared to other silane halides. In atomic layer deposition (ALD) film formation processes, it can rapidly form uniform and dense silicon nitride (N-Si) films within a relatively low temperature window. These deposited N-Si films can meet the requirements of integrated circuit chip manufacturing processes. Therefore, diiodosilane is widely used in advanced semiconductor chip manufacturing and is an indispensable silicon-based precursor material with broad application prospects.

[0003] Currently, the main methods for synthesizing diiodosilanes are as follows: 1. A method using phenylsilane and elemental iodine in a haloalkanes solvent with oxygen-containing organic compounds as catalysts to prepare diiodosilanes, as described in literature CN110606491A; 2. A method using dichlorosilane and lithium iodide to prepare diiodosilanes, which is a halogen exchange method. For example, WO2019 / 212808A1 reports a method for preparing diiodosilanes from dichlorosilane and solid lithium iodide. Both of these methods require distillation of the mother liquor after the reaction to obtain diiodosilanes with high purity. However, because the solvents and catalysts used are close to the boiling points of diiodosilanes, conventional distillation purification methods are difficult to achieve high purity. Furthermore, the yield of diiodosilanes is low, and a large amount of diiodosilane remains in the mother liquor, making separation difficult. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a distillation purification method for diiodosilane. This invention utilizes a two-stage distillation system to purify diiodosilane, achieving continuous distillation purification. By distilling the diiodosilane mother liquor at different temperatures, the yield of diiodosilane is improved. Simultaneously, the use of a preheating mechanism for heat exchange between the diiodosilane mother liquor and diiodosilane vapor reduces energy consumption and also improves the purity of diiodosilane.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for purifying diiodosilane by distillation utilizes a two-stage distillation system. The two-stage system includes a first distillation column and a second distillation column. The inlet of the first distillation column is connected to a mother liquor tank via a first feed pump. The outlet of the first distillation column is connected to the inlet of a heat exchanger. The outlet of the heat exchanger is connected to the inlet of a condenser. The outlet of the condenser is connected to a pure product tank via a discharge pump. The outlet of the condenser is connected to a tail gas treatment system via an exhaust pump. The outlet of the heat exchanger is connected to both a first heater and a second heater. The equipment is connected as follows: the first heater is connected to the heat medium inlet of the first distillation column via the first circulating pump; the liquid outlet at the bottom of the first distillation column is connected to the transfer tank; the liquid outlet of the transfer tank is connected to the liquid inlet of the second distillation column via the second feed pump; the gas outlet of the second distillation column is connected to the gas inlet of the heat exchanger; the second heater is connected to the heat medium inlet of the second distillation column via the second circulating pump; the heat medium outlets of both the first and second distillation columns are connected to the liquid inlet of the heat exchanger; and the liquid outlet at the bottom of the second distillation column is connected to the recovery tank.

[0007] The distillation purification method for diiodosilane specifically includes the following steps:

[0008] S1. The diiodosilane mother liquor is added to the first distillation column through the first feed pump. After being preheated by the preheating mechanism of the first distillation column, the diiodosilane mother liquor overflows into the lower column body. The diiodosilane mother liquor is heated to the preset temperature T1 by the heat medium for distillation.

[0009] S2. After distillation, the diiodosilane mother liquor is distilled. The diiodosilane vapor generated in the lower column of the first distillation column is preheated and then exchanged with the vapor at the top of the column through a heat exchanger. Then it is condensed by a condenser to obtain pure diiodosilane. The pure diiodosilane flows into the pure product tank through the discharge pump. The non-condensable gas is treated by the tail gas treatment system.

[0010] S3. The residual mother liquor at the bottom of the lower column of the first distillation column is stored in a transfer tank and then fed into the second distillation column by the second feed pump. The residual mother liquor is preheated by the preheating mechanism of the second distillation column and overflows into the lower column. The residual mother liquor is heated to the preset temperature T2 by the heat medium for distillation.

[0011] S4. The residual mother liquor is distilled, and the diiodosilane vapor generated in the lower column of the second distillation column is preheated and then exchanged with the vapor at the top of the column through a heat exchanger. The vapor is then condensed by a condenser to obtain pure diiodosilane. The pure diiodosilane flows into the pure product tank through a discharge pump. The non-condensable gas is treated by the tail gas treatment system. The residual liquid at the bottom of the lower column of the second distillation column enters the recovery tank and is recycled after further separation.

[0012] More preferably, the diiodosilane mother liquor is the mother liquor obtained by reacting dichlorosilane with lithium iodide to prepare diiodosilane, and the diiodosilane mother liquor includes diiodosilane, solvent, catalyst and unreacted lithium iodide.

[0013] More preferably, in step S1, 55℃≤T1≤60℃, in step S3, 60℃≤T2≤65℃, and T2-T1≥5℃.

[0014] More preferably, the first distillation column includes a column body, with a preheating mechanism fixedly installed at the top inside the column body. The preheating mechanism includes a feed tray, which is fixedly installed on the upper inner wall of the column body. The feed tray has a hollow structure. A feed pipe is fixedly installed on the outer wall of the column body corresponding to the feed tray, and the feed pipe is connected to the inside of the feed tray. A baffle plate is fixedly installed on the inner wall of the column body above the feed tray, and several heat exchange tubes are provided between the feed tray and the baffle plate. A hopper is fixedly installed on the inner wall of the column body below the feed tray, and a gas guide pipe is fixedly installed on the outer wall of the column body, connecting... The space below the hopper and between the feed tray and the partition is used to construct a column body outlet pipe fixedly installed on the outer wall of the column body, and a column top outlet pipe fixedly installed on the top of the column body. The column body outlet pipe and the column top outlet pipe are connected by a tee pipe. A heating mechanism is fixedly installed at the bottom of the column body. The heating mechanism includes heating pipes arranged around the column. A heat medium inlet pipe and a heat medium outlet pipe are fixedly installed on the outer wall of the column body corresponding to the heating pipes. The two ends of the heating pipes are connected to the heat medium inlet pipe and the heat medium outlet pipe, respectively. A discharge pipe is provided at the bottom of the column body. The structure of the second distillation column is the same as that of the first distillation column.

[0015] More preferably, the heat exchange tube includes a concentrically arranged outer heat exchange tube and an inner heat exchange tube, both of which are hollow tubes. The lower end of the outer heat exchange tube is fixed to the top surface of the feed pan, and the bottom end of the outer heat exchange tube communicates with the inside of the feed pan. The upper end of the outer heat exchange tube passes through a partition plate. The lower end of the inner heat exchange tube is fixed to the bottom surface of the feed pan, and the bottom end of the inner heat exchange tube communicates with the discharge hopper. The top of the inner heat exchange tube is lower than that of the outer heat exchange tube.

[0016] More preferably, in step S1, the diiodosilane mother liquor first enters the feed pan through the feed pipe. As the diiodosilane mother liquor is continuously added, the liquid level of the diiodosilane mother liquor in the outer heat exchange tube continuously rises until the liquid level is level with the top of the inner heat exchange tube. Then, the diiodosilane mother liquor flows from the inside of the inner heat exchange tube into the drop hopper below the feed pan.

[0017] More preferably, the tower body exhaust pipe is L-shaped, the bottom end of the horizontal section of the tower body exhaust pipe is flush with the top surface of the feed pan, a reflux box is fixedly installed on the outer wall of the tower body below the exhaust pipe, the top of the reflux box is connected to the bottom of the horizontal section of the exhaust pipe, a reflux pipe is fixedly installed at the bottom of the reflux box, and a U-shaped bend is provided at the lower end of the reflux pipe. The reflux box is connected to the tower body below the hopper through the reflux pipe.

[0018] More preferably, the top side of the reflux box is connected to the inside of the feed tray, and a solenoid valve is installed inside the connecting pipe between the reflux pipe and the feed tray.

[0019] More preferably, in step S2, the diiodosilane vapor generated in the lower tower body enters the space between the feed tray and the baffle through the gas guide pipe, and completes heat exchange with the diiodosilane mother liquor flowing inside the heat exchange tube, thereby preheating the diiodosilane mother liquor. The diiodosilane vapor after heat exchange flows out through the gas outlet pipe of the tower body. During the heat exchange process, some of the gas condenses into liquid and flows into the reflux box through the bottom of the gas outlet pipe of the tower body.

[0020] More preferably, the hopper includes a conical hopper body, the top of the hopper body is fixedly connected to the bottom of the feed plate, a discharge pipe is fixedly installed in the middle of the bottom of the hopper body, and the lower end of the discharge pipe is also provided with a U-shaped bend.

[0021] The beneficial effects of this invention are:

[0022] This invention purifies diiodosilane using a two-stage distillation system, achieving continuous distillation purification of diiodosilane. After the diiodosilane mother liquor is distilled in the first distillation column, the residual mother liquor may still contain unevaporated diiodosilane. This is then further purified by increasing the distillation temperature in the second distillation column, thereby increasing the diiodosilane yield. The evaporation temperature can also be adjusted based on the solvent and catalyst content at the outlets of the first and second distillation columns, thereby reducing impurity content and improving the purity of the diiodosilane.

[0023] This invention uses a gas guide pipe to preheat the diiodosilane mother liquor via a preheating mechanism. This reduces the energy consumption required for heating the heat medium in the heating mechanism and cools the diiodosilane vapor. Since some solvent and catalyst inevitably get trapped in the diiodosilane vapor during the re-evaporation process, and these solvents and catalysts have higher boiling points than diiodosilane, the preheating mechanism cools the diiodosilane vapor, causing the trapped solvents and catalysts to condense into liquid and flow from the tower outlet pipe into the reflux box, and then back into the tower body. This reduces the impurity content in the diiodosilane vapor and further improves the purity of diiodosilane. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the two-stage distillation system of the present invention;

[0026] Figure 2 This is a schematic diagram of the overall structure of the first distillation column of the present invention;

[0027] Figure 3 This is the present invention. Figure 2 Enlarged view of location A;

[0028] Figure 4 This is the present invention. Figure 2 Enlarged view of location B;

[0029] Figure 5 This is the present invention. Figure 2 Enlarged view of location C.

[0030] In the diagram: 1-First distillation column, 2-Second distillation column, 3-First feed pump, 4-Heat exchanger, 5-Condenser, 6-Discharge pump, 7-Pure product tank, 8-Exhaust pump, 9-First heater, 10-First circulation pump, 12-Second feed pump, 13-Second heater, 14-Second circulation pump, 15-Recovery tank, 16-Column body, 17-Preheating mechanism, 18-Feed tray, 19-Feed pipe 20-Baffle plate, 21-Heat exchange tube, 22-Feed hopper, 23-Gas guide pipe, 24-Tower body gas outlet pipe, 25-Tower top gas outlet pipe, 26-Heating mechanism, 27-Heating tube, 28-Heat medium inlet pipe, 29-Heat medium outlet pipe, 30-Discharge pipe, 31-Heat exchange outer tube, 32-Heat exchange inner tube, 33-Reflux box, 34-Reflux pipe, 35-Solenoid valve, 36-Hopper body, 37-Feed pipe. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] A two-stage distillation system includes a first distillation column 1 and a second distillation column 2. The inlet of the first distillation column 1 is connected to a mother liquor tank via a first feed pump 3. The outlet of the first distillation column 1 is connected to the inlet of a heat exchanger 4. The outlet of the heat exchanger 4 is connected to the inlet of a condenser 5. The outlet of the condenser 5 is connected to a pure product tank 7 via a discharge pump 6. The outlet of the condenser 5 is connected to a tail gas treatment system via an exhaust pump 8. The outlet of the heat exchanger 4 is connected to a first heater 9 and a second heater 13. The first heater 9 is connected to a first circulation system. Pump 10 is connected to the heat medium inlet of the first distillation column 1. The bottom outlet of the first distillation column 1 is connected to the transfer tank 11. The outlet of the transfer tank 11 is connected to the inlet of the second distillation column 2 via the second feed pump 12. The gas outlet of the second distillation column 2 is connected to the gas inlet of the heat exchanger 4. The second heater 13 is connected to the heat medium inlet of the second distillation column 2 via the second circulation pump 14. The heat medium outlets of both the first and second distillation columns 1 and 2 are connected to the inlet of the heat exchanger 4. The bottom outlet of the second distillation column 2 is connected to the recovery tank 15. After the diiodosilane mother liquor is distilled through the first distillation column 1, there may still be unevaporated diiodosilane in the residual mother liquor. Further distillation through the second distillation column 2 increases the distillation temperature, thereby further evaporating the diiodosilane and increasing its yield.

[0033] The first distillation column 1 includes a column body 16. A preheating mechanism 17 is fixedly installed inside the upper part of the column body 16. The preheating mechanism 17 includes a feed tray 18, which is fixedly installed on the upper inner wall of the column body 16. The feed tray 18 has a hollow structure. A feed pipe 19 is fixedly installed on the outer wall of the column body 16 corresponding to the feed tray 18. The feed pipe 19 is connected to the inside of the feed tray 18. A baffle plate 20 is fixedly installed on the inner wall of the column body 16 above the feed tray 18. Several heat exchange tubes 21 are provided between the feed tray 18 and the baffle plate 20. A hopper 22 is fixedly installed on the inner wall of the column body 16 below the feed tray 18. A gas guide pipe 23 is fixedly installed on the outer wall of the column body 16. The gas guide pipe 23 is connected to... The space below the hopper 22 and between the feed tray 18 and the partition plate 20 is used to fix the tower body outlet pipe 24 on the outer wall of the tower body 16 and the top outlet pipe 25 on the top of the tower body 16. The tower body outlet pipe 24 and the top outlet pipe 25 are connected by a three-way pipe. The heating mechanism 26 is fixedly installed inside the lower part of the tower body 16. The heating mechanism 26 includes heating pipes 27 arranged around the tower body. The heat medium inlet pipe 28 and heat medium outlet pipe 29 are fixedly installed on the outer wall of the tower body 16 corresponding to the heating pipes 27. The two ends of the heating pipes 27 are connected to the heat medium inlet pipe 28 and the heat medium outlet pipe 29, respectively. The bottom of the tower body 16 is provided with a discharge pipe 30. The structure of the second distillation tower 2 is the same as that of the first distillation tower 1.

[0034] The heat exchange tube 21 includes a concentrically arranged heat exchange outer tube 31 and heat exchange inner tube 32. Both the heat exchange outer tube 31 and the heat exchange inner tube 32 are hollow tubes. The lower end of the heat exchange outer tube 31 is fixed to the top surface of the feed pan 18, and the bottom end of the heat exchange outer tube 31 is connected to the inside of the feed pan 18. The upper end of the heat exchange outer tube 31 passes through the partition plate 20. The lower end of the heat exchange inner tube 32 is fixed to the bottom surface of the feed pan 18, and the bottom end of the heat exchange inner tube 32 is connected to the discharge hopper 22. The top end of the heat exchange inner tube 32 is lower than that of the heat exchange outer tube 31. The tower body exhaust pipe 24 is L-shaped. The bottom of the horizontal section of the exhaust pipe 24 is flush with the top surface of the feed pan 18. A reflux box 33 is fixedly installed on the outer wall of the tower body 16 below the exhaust pipe 24. The top of the reflux box 33 is connected to the bottom of the horizontal section of the exhaust pipe 24. A reflux pipe 34 is fixedly installed at the bottom of the reflux box 33. The lower end of the reflux pipe 34 has a U-shaped bend. The reflux box 33 is connected to the tower body 16 below the hopper 22 through the reflux pipe 34. One side of the top of the reflux box 33 is connected to the inside of the feed pan 18. A solenoid valve 35 is installed inside the connecting pipe between the reflux pipe 34 and the feed pan 18.

[0035] The evaporated diiodosilane vapor is preheated by the preheating mechanism 17 through the gas guide pipe 23. This reduces the energy consumption required for heating the heat medium 26 of the heating mechanism and cools the diiodosilane vapor. Since some solvent and catalyst will inevitably be mixed in the diiodosilane vapor during the re-evaporation of diiodosilane, and the boiling points of the solvent and catalyst are higher than those of diiodosilane, the preheating mechanism 17 can cool the diiodosilane vapor so that the mixed solvent and catalyst can first condense into liquid and flow from the gas outlet pipe of the tower body into the reflux box 33, and then flow back into the tower body 16. This reduces the impurity content in the diiodosilane vapor and improves the purity of diiodosilane.

[0036] The hopper 22 includes a conical hopper body 36. The top of the hopper body 36 is fixedly connected to the bottom of the feed plate 18. A discharge pipe 37 is fixedly installed in the middle of the bottom of the hopper body 36. The end of the discharge pipe 37 is also provided with a U-shaped bend.

[0037] A method for purifying diiodosilane using the above-mentioned two-stage distillation system, wherein the diiodosilane mother liquor is obtained from the reaction of dichlorosilane with lithium iodide to prepare diiodosilane, and the diiodosilane mother liquor includes diiodosilane, solvent, catalyst, and unreacted lithium iodide, specifically including the following steps:

[0038] S1. The diiodosilane mother liquor is added to the first distillation column through the first feed pump. The diiodosilane mother liquor first enters the feed pan through the feed pipe. As the diiodosilane mother liquor is continuously added, the liquid level of the diiodosilane mother liquor in the outer heat exchange tube continuously rises until the liquid level is level with the top of the inner heat exchange tube. Then, the diiodosilane mother liquor flows from the inside of the inner heat exchange tube into the hopper below the feed pan and enters the lower column body through the hopper. The diiodosilane mother liquor is heated to 55°C by the heat medium for distillation.

[0039] S2. After distillation, diiodosilane mother liquor is distilled, and diiodosilane vapor enters the space between the feed tray and the baffle through the gas guide pipe. It exchanges heat with the diiodosilane mother liquor flowing inside the heat exchange tube, thereby preheating the diiodosilane mother liquor. The diiodosilane vapor after heat exchange flows out through the gas outlet pipe of the tower body. During the heat exchange process, some of the gas condenses into liquid and flows into the reflux box through the bottom of the gas outlet pipe of the tower body. After passing through the preheating mechanism, the diiodosilane vapor and the top steam of the tower exchange heat together in the heat exchanger. Then, it is condensed by the condenser to obtain pure diiodosilane. The pure diiodosilane flows into the pure product tank through the discharge pump, and the non-condensable gas is treated through the tail gas treatment system.

[0040] S3. The residual mother liquor at the bottom of the lower column of the first distillation column is stored in a transfer tank and then fed into the second distillation column by the second feed pump. The residual mother liquor is preheated by the preheating mechanism of the second distillation column and overflows into the lower column. The residual mother liquor is heated to 60°C by the heat medium for distillation.

[0041] S4. The residual mother liquor is distilled, and the diiodosilane vapor generated in the lower column of the second distillation column is preheated and then exchanged with the vapor at the top of the column through a heat exchanger. The vapor is then condensed by a condenser to obtain pure diiodosilane. The pure diiodosilane flows into the pure product tank through a discharge pump. The non-condensable gas is treated by the tail gas treatment system. The residual liquid at the bottom of the lower column of the second distillation column enters the recovery tank and is recycled after further separation.

[0042] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for the distillation purification of diiodosilane, characterized in that, Purification is achieved using a two-stage distillation system, comprising a first distillation column and a second distillation column. The inlet of the first distillation column is connected to a mother liquor tank via a first feed pump. The outlet of the first distillation column is connected to the inlet of a heat exchanger. The outlet of the heat exchanger is connected to the inlet of a condenser. The outlet of the condenser is connected to a pure product tank via a discharge pump. The outlet of the condenser is connected to a tail gas treatment system via an exhaust pump. The outlet of the heat exchanger is connected to a first heater and a second heater. The first heater is connected to the heat medium inlet of the first distillation column via a first circulation pump. The bottom outlet of the first distillation column is connected to a transfer tank. The outlet of the transfer tank is connected to the inlet of the second distillation column via a second feed pump. The outlet of the second distillation column is connected to the inlet of the heat exchanger. The second heater is connected to the heat medium inlet of the second distillation column via a second circulation pump. The heat medium outlets of both the first and second distillation columns are connected to the inlets of the heat exchangers. The bottom outlet of the second distillation column is connected to a recovery tank. The distillation purification method for diiodosilane specifically includes the following steps: S1. The diiodosilane mother liquor is added to the first distillation column through the first feed pump. After being preheated by the preheating mechanism of the first distillation column, the diiodosilane mother liquor overflows into the lower column body. The diiodosilane mother liquor is heated to the preset temperature T1 by the heat medium for distillation. S2. After distillation, the diiodosilane mother liquor is distilled. The diiodosilane vapor generated in the lower column of the first distillation column is preheated and then exchanged with the vapor at the top of the column through a heat exchanger. Then it is condensed by a condenser to obtain pure diiodosilane. The pure diiodosilane flows into the pure product tank through the discharge pump. The non-condensable gas is treated by the tail gas treatment system. S3. The residual mother liquor at the bottom of the lower column of the first distillation column is stored in a transfer tank and then fed into the second distillation column by the second feed pump. The residual mother liquor is preheated by the preheating mechanism of the second distillation column and overflows into the lower column. The residual mother liquor is heated to the preset temperature T2 by the heat medium for distillation. S4. The residual mother liquor is distilled, and the diiodosilane vapor generated in the lower column of the second distillation column is preheated and then exchanged with the vapor at the top of the column through a heat exchanger. Then it is condensed by a condenser to obtain pure diiodosilane. The pure diiodosilane flows into the pure product tank through the discharge pump. The non-condensable gas is treated by the tail gas treatment system. The residual liquid at the bottom of the lower column of the second distillation column enters the recovery tank and is recycled after further separation. The diiodosilane mother liquor is the mother liquor obtained by reacting dichlorosilane with lithium iodide to prepare diiodosilane. The diiodosilane mother liquor includes diiodosilane, solvent, catalyst and unreacted lithium iodide. In step S1, 55℃≤T1≤60℃; in step S3, 60℃≤T2≤65℃; and T2-T1≥5℃. In step S2, the diiodosilane vapor generated in the lower tower enters the space between the feed tray and the baffle through the gas guide pipe, and exchanges heat with the diiodosilane mother liquor flowing inside the heat exchange tube, thereby preheating the diiodosilane mother liquor. The diiodosilane vapor after heat exchange flows out through the gas outlet pipe of the tower body. During the heat exchange process, some of the gas condenses into liquid and flows into the reflux box through the bottom of the gas outlet pipe of the tower body.

2. The distillation purification method for diiodosilane according to claim 1, characterized in that, The first distillation column includes a column body. A preheating mechanism is fixedly installed inside the upper part of the column body. The preheating mechanism includes a feed tray, which is fixedly installed on the upper inner wall of the column body. The feed tray has a hollow interior. A feed pipe is fixedly installed on the outer wall of the column body corresponding to the feed tray, and the feed pipe is connected to the interior of the feed tray. A baffle plate is fixedly installed on the inner wall of the column body above the feed tray. Several heat exchange tubes are provided between the feed tray and the baffle plate. A hopper is fixedly installed on the inner wall of the column body below the feed tray. A gas guide pipe is fixedly installed on the outer wall of the column body, and the gas guide pipe is connected to... The space below the hopper and between the feed tray and the partition is used for the following: a tower body outlet pipe is fixedly installed on the outer wall of the tower body; a tower top outlet pipe is fixedly installed on the top of the tower body; the tower body outlet pipe and the tower top outlet pipe are connected by a tee pipe; a heating mechanism is fixedly installed at the bottom of the tower body; the heating mechanism includes a heating pipe arranged around the tower body; a heat medium inlet pipe and a heat medium outlet pipe are fixedly installed on the outer wall of the tower body corresponding to the heating pipe; the two ends of the heating pipe are respectively connected to the heat medium inlet pipe and the heat medium outlet pipe; and a discharge pipe is provided at the bottom of the tower body. The structure of the second distillation tower is the same as that of the first distillation tower.

3. The distillation purification method for diiodosilane according to claim 2, characterized in that, The heat exchange tube includes a concentrically arranged outer heat exchange tube and an inner heat exchange tube, both of which are hollow tubes. The lower end of the outer heat exchange tube is fixed to the top surface of the feed pan, and the bottom end of the outer heat exchange tube communicates with the interior of the feed pan. The upper end of the outer heat exchange tube passes through a partition plate. The lower end of the inner heat exchange tube is fixed to the bottom surface of the feed pan, and the bottom end of the inner heat exchange tube communicates with the discharge hopper. The top end of the inner heat exchange tube is lower than that of the outer heat exchange tube.

4. The distillation purification method for diiodosilane according to claim 3, characterized in that, In step S1, the diiodosilane mother liquor first enters the feed pan through the feed pipe. As the diiodosilane mother liquor is continuously added, the liquid level of the diiodosilane mother liquor in the outer heat exchange tube continuously rises until the liquid level is level with the top of the inner heat exchange tube. Then, the diiodosilane mother liquor flows from the inside of the inner heat exchange tube into the drop hopper below the feed pan.

5. The distillation purification method for diiodosilane according to claim 2, characterized in that, The tower body exhaust pipe is L-shaped. The bottom end of the horizontal section of the tower body exhaust pipe is flush with the top surface of the feed tray. A reflux box is fixedly installed on the outer wall of the tower body below the exhaust pipe. The top of the reflux box is connected to the bottom of the horizontal section of the exhaust pipe. A reflux pipe is fixedly installed at the bottom of the reflux box. The lower end of the reflux pipe is provided with a U-shaped bend. The reflux box is connected to the tower body below the hopper through the reflux pipe.

6. The distillation purification method for diiodosilane according to claim 5, characterized in that, The top side of the reflux box is connected to the inside of the feed tray, and a solenoid valve is installed inside the connecting pipe between the reflux pipe and the feed tray.

7. The distillation purification method for diiodosilane according to claim 2, characterized in that, The hopper includes a conical hopper body, the top of which is fixedly connected to the bottom of the feed plate, and a discharge pipe is fixedly installed in the middle of the bottom of the hopper body. The lower end of the discharge pipe is also provided with a U-shaped bend.

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