Preparation method and preparation device of trimethyl aluminum

Abstract

The invention relates to the technical field of preparation of trimethylaluminum, and particularly discloses a preparation method of trimethylaluminum, which comprises the following steps: preparing raw materials: solvent oil, aluminum powder, metal sodium and chloromethane; reaction: sequentially putting the raw materials into a reaction kettle for reaction; distilling to obtain a crude product: distilling out the trimethyl aluminum crude product through a distillation process, cooling the residual liquid in the kettle, and discharging from a discharge port; and rectification: transferring the trimethylaluminum crude product into a rectification kettle, and carrying out heating rectification under a normal pressure condition. According to the preparation method of the trimethylaluminum, the reaction process is promoted by adding sodium, improving the activity of aluminum, reducing side reactions, cleaning the surface of the aluminum and improving the purity, so that the reaction method of the aluminum and the organic halide is more efficient and high in yield. Sodium has multiple functions and can optimize reaction conditions and improve the quality of a final product, and meanwhile, unqualified products are treated again through sampling detection, so that the reaction purity is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of trimethylaluminum preparation, and in particular to a method for preparing trimethylaluminum and a preparation device thereof. Background Art

[0002] Trimethylaluminum is a highly reactive chemical substance, mainly used in the following fields: organic synthesis, semiconductor industry, aerospace industry, surface treatment and other fields. It is now mostly used as a catalyst in certain types of organic reactions, such as catalysts for olefin polymerization reactions, and solar cell manufacturing processes, such as PERC and TOPCON cell preparation processes.

[0003] Existing trimethylaluminum preparation methods can be mainly summarized as follows: (1) Methyl iodide and methyl bromide react with aluminum-magnesium alloy to form trimethylaluminum. The reaction is carried out in a hydrocarbon solvent. Methyl iodide and methyl bromide are used. The raw materials are expensive, resulting in high production costs. Methyl chloride, which is a low-priced raw material, hardly reacts with aluminum-magnesium alloy.

[0004] Recently Chinese patent CN04774218B, CN105175440A, CN104774219A all disclose monohalomethane and metal alloy Al / Mg and obtain trimethyl aluminum etheric complex in ether solvent, and coordination ether is through with high-boiling organic tertiary amine or organophosphine replacement after pyrolysis and obtains the method for pure trimethyl aluminum.Use ether solvent to improve the activity and productive rate of reaction, but the trimethyl aluminum etheric adduct formed needs to be replaced through amine or phosphine ligand, slough new amino ligand or phosphine ligand again after the displacement, this has just increased the complexity of production technique, simultaneously because ether ligand and trimethyl aluminum are firmly combined, be difficult to remove fully, trimethyl aluminum purity is low, can not meet use requirements.The monohalomethane used is a methyl iodide or a methyl bromide, and the raw material price height causes production cost height.

[0005] (2) U.S. Patents No. 4925962, No. 4948906, No. 5543537, and No. 4364873 disclose methods for the alkyl exchange reaction of high-chain alkyl aluminum with a halogenated alkane to produce trimethyl aluminum and a high-chain halogenated hydrocarbon. Patent documents disclose that the alkyl exchange method for preparing trimethyl aluminum usually requires an auxiliary reaction. In this preparation method, triethyl aluminum is used as a raw material, and trimethyl aluminum is formed through ligand exchange in the presence of a Lewis acid catalyst such as BiCl3, VOCl3, etc. The disadvantages of this method are: the amount of triethyl aluminum must be excessive, the cost of raw materials is high, the exchange reaction is not thorough, a large number of by-products are formed, and the conversion rate is low. At the same time, the use of a relatively expensive catalyst causes the production cost of trimethyl aluminum to be too high. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing trimethylaluminum to solve the above-mentioned shortcomings in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: A method for preparing trimethylaluminum comprises the following steps: S1: Raw material preparation: solvent oil, aluminum powder, metallic sodium and methyl chloride; S2: reaction: the above raw materials are placed in the reactor in order to react; S3: Distilling to obtain a crude product: The crude trimethylaluminum is distilled out, and the remaining residual liquid in the kettle is discharged from the discharge port after cooling; S4: distillation: the crude trimethylaluminum is transferred to a distillation kettle and heated for distillation under normal pressure; S5: Sampling and testing: Sample the above products for testing. If the test is qualified, the product will be canned. If the test is unqualified, repeat the subsequent actions of S3.

[0008] Further, said S2 comprises the following steps: S21: Pour a certain amount of solvent oil into the reactor; S22: Add aluminum powder, heat and evacuate, then gradually add methyl chloride to react; S23: When the amount of chloromethane added reaches the set value, the reaction is determined to be terminated; S24: The calculated metallic sodium is processed into a columnar shape through equipment, and the sodium is added to the reactor in batches according to the temperature of the reactor.

[0009] Furthermore, the residual liquid in S3 is finally taken to a hydrolysis station to hydrolyze and recover the solvent oil therein.

[0010] Furthermore, the crude trimethylaluminum in S3 is first temporarily stored in a crude product storage tank, and then transferred from the crude product transfer tank to the distillation kettle by nitrogen.

[0011] Further, said S4 includes the following steps: S41, adjusting the distillation rate by setting the temperature of the distillation kettle heating circulator, receiving the fraction before the tower top temperature reaches the standard value into the pre-fraction receiving tank, and receiving the fraction after the tower top temperature reaches the standard value into the main distillate receiving tank; S42, the product in the front fraction receiving tank is transferred to the front fraction storage tank, and the product in the main fraction receiving tank is transferred to the main fraction storage tank; S42, when the distillation in the distillation kettle is completed, the system cools down and waits for the next batch of material transfer production.

[0012] Furthermore, the residual liquid remaining in the distillation kettle in S4 is transferred to the preparation kettle through an inner extension tube for crude distillation separation, the trimethylaluminum in the residual liquid re-enters the crude product tank, and the solvent oil in the residual liquid is hydrolyzed and recovered.

[0013] A trimethylaluminum preparation device adopts the above-mentioned trimethylaluminum preparation method, comprising a reactor, a feed pipe provided on the top of the reactor, a flow guide component provided inside the reactor, the flow guide component comprising an annular liquid storage tank, a first liquid outlet opening provided at the bottom of the annular liquid storage tank, and a flow guide plate provided at the bottom of the annular liquid storage tank. The flow guide plate is arranged in an inclined manner and is used to cause liquid sodium to flow down along the inner wall of the reactor during its falling process, thereby reducing the falling speed.

[0014] Furthermore, an adjusting component is provided on the guide plate, and the adjusting component includes a connecting pipe connected to the bottom of the feed pipe. During the descending process of the connecting pipe, the guide plate is driven to rotate to the second angle position, so that the liquid falls quickly.

[0015] In the above technical solution, the preparation method of trimethylaluminum provided by the present invention has the beneficial effects of: The addition of sodium bars accelerates the reaction process by increasing aluminum activity, reducing side reactions, cleaning the aluminum surface, and improving purity, thereby making the aluminum-organic halide reaction more efficient and high-yielding. Sodium has a multifaceted role, optimizing reaction conditions and improving the quality of the final product. Furthermore, through sampling and testing, substandard products can be distilled again to increase reaction purity.

[0016] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0017] This application document provides an overview of various implementations or examples of the technology described in this disclosure, and is not a comprehensive disclosure of the full scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0019] Figure 1 A crude product distillation flow chart provided in Example 1 of the present invention; Figure 2 The distillation flow chart provided in Example 1 of the present invention; Figure 3 A schematic diagram of the overall external structure provided by Example 3 of the present invention; Figure 4 A schematic diagram of a partial cross-sectional structure of a reactor provided in Example 3 of the present invention; Figure 5 A schematic diagram of the structure of a guide plate provided in Example 3 of the present invention; Figure 6 A schematic diagram of the liquid flow direction structure provided in Example 3 of the present invention; Figure 7 A schematic diagram of the internal structure of a reactor provided in Example 5 of the present invention; Figure 8 Provided in Example 5 of the present invention Figure 7 A schematic diagram of the enlarged structure at point A; Figure 9 A bottom view schematic diagram of the reciprocating component provided in Example 5 of the present invention; Figure 10 This is a schematic diagram of the internal structure of the connecting pipe provided in Example 5 of the present invention.

[0020] Description of reference numerals: 1. Reactor; 2. Flow guide component; 21. Feed hopper; 22. Feed pipe; 23. Connecting pipe; 24. Annular liquid storage tank; 25. Liquid outlet; 26. Flow guide plate; 261. Baffle bar; 262. Fitting part; 3. Stirring blade; 4. Reducer motor; 5. Drive shaft; 6. Interference block; 7. Reciprocating component; 71. Drive screw; 72. Moving sleeve; 73. Snap ring; 74. Electromagnet; 75. Pulley; 76. Transmission belt; 77. Baffle ring. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0022] Example 1, please refer to 1-2, a method for preparing trimethylaluminum, including a preparation device, and the steps are as follows: Raw material preparation: solvent oil, aluminum powder, metallic sodium block and methyl chloride; Reaction: Place the above raw materials into the reactor in order to react; Specifically, a certain amount of solvent oil is first poured into a reactor, aluminum powder is added, and after heating, methyl chloride is gradually added to react. When the amount of methyl chloride added reaches the calculated amount, the reaction is determined to be terminated; the calculated metallic sodium is pre-prepared into strip-shaped sodium blocks, and the sodium blocks are added to the reactor in batches according to the temperature of the reactor.

[0023] Distillation to obtain crude product: The crude trimethylaluminum is evaporated by distillation process, and the residual liquid in the kettle is discharged from the discharge port after cooling; Distillation: Transfer the crude trimethylaluminum to a distillation kettle and heat and distill under normal pressure; Sampling and testing: Take samples of the above products for testing. If they pass the test, they will be canned. If they fail the test, repeat the above steps.

[0024] The specific process is as follows: After a fixed amount of solvent oil is pumped into the preparation kettle, aluminum powder is added and heating is started. When the temperature in the kettle reaches above 120°C, chloromethane is gradually added for reaction. When the pressure in the kettle no longer decreases after the chloromethane reaction reaches the later stage, the reaction is determined to be terminated. The calculated amount of metallic sodium is then pre-prepared into strips of sodium blocks. Sodium is added to the kettle in batches according to the temperature of the reactor. After the addition of sodium, the crude trimethylaluminum is distilled out by distillation. The remaining residual liquid in the kettle is cooled and discharged from the discharge port. The residual liquid is hydrolyzed and deactivated, and the organic and inorganic phases are separated to recover the solvent oil. The crude product is temporarily stored in a crude product storage tank, awaiting further purification in the distillation process.

[0025] The crude trimethylaluminum product is transferred from the crude product transfer tank to the distillation kettle for heating and distillation under normal pressure. The distillation rate is adjusted by the set temperature of the distillation kettle's heating circulator. The fraction before the tower top temperature reaches the target value is collected in the pre-fraction receiving tank, while the fraction after the tower top temperature reaches the target value is collected in the main distillate receiving tank. The product in the pre-fraction receiving tank is transferred to the pre-fraction storage tank, and the product in the main distillate receiving tank is transferred to the main distillate storage tank. After the distillation in the distillation kettle is completed, the system cools down and waits for the next batch of material transfer. The product in the main distillate storage tank is sampled and tested.

[0026] After passing the test, the product is canned. If it fails the test, it is returned to the crude product tank for reprocessing. The residual liquid left in the distillation kettle is transferred to the preparation kettle through an internal extension pipe for crude distillation separation. The trimethylaluminum in the residual liquid is re-entered into the crude product tank, and the solvent oil in the residual liquid is directly discharged from the preparation kettle and pulled to the hydrolysis station for hydrolysis and recovery.

[0027] Example 2, a method for preparing trimethylaluminum, including a preparation device, and the steps are as follows: Raw material preparation: solvent oil, aluminum powder, metallic sodium block and methyl chloride; Reaction: Place the above raw materials into the reactor in order to react; Specifically, a certain amount of solvent oil is first poured into a reactor, aluminum powder is added, and chloromethane is gradually added after heating to react. When the amount of chloromethane added reaches the calculated amount, the reaction is determined to be terminated; the calculated amount of metallic sodium is put into a molten sodium reactor at one time and heated to melt. After the metallic sodium is completely melted, sodium is gradually added to the reactor according to the temperature of the reactor.

[0028] Distillation to obtain crude product: The crude trimethylaluminum is evaporated by distillation process, and the residual liquid in the kettle is discharged from the discharge port after cooling; Distillation: Transfer the crude trimethylaluminum to a distillation kettle and heat and distill under normal pressure; Sampling and testing: Take samples of the above products for testing. If they pass the test, they will be canned. If they fail the test, repeat the above steps.

[0029] The remaining specific steps are the same as those in Example 1 and will not be described in detail here.

[0030] Example 3, please refer to Figure 3-6 A device for preparing trimethylaluminum adopts the method for preparing trimethylaluminum of Example 2, comprising a reactor 1, a feed pipe 22 being provided on the top of the reactor 1, a feed hopper 21 being fixedly connected to the top of the feed pipe 22, a flow guide component 2 being provided inside the reactor 1, the flow guide component 2 comprising an annular liquid storage tank 24, a liquid outlet 25 being provided at the bottom of the annular liquid storage tank 24, a flow guide plate 26 being provided at the bottom of the annular liquid storage tank 24, the flow guide plate 26 being arranged at an angle, and being used for causing the liquid sodium to flow down along the inner wall of the reactor 1 during the falling process, so as to reduce the falling speed.

[0031] In this embodiment, the annular liquid storage tank 24 is fixedly connected to the inner wall of the reactor 1 .

[0032] Specifically, the guide plate 26 has an inclination angle of 15-75 degrees, the feed pipe 22 is made of high-temperature resistant material, and the reactor 1 is made of 304 stainless steel, which can withstand a high temperature of 150 degrees.

[0033] During the downward flow of the liquid sodium, it will flow along the guide plate 26 to the inner wall of the reactor 1. The flow rate will be reduced by the friction with the reactor 1 and the surface tension of the liquid sodium. At the same time, the reactor 1 is tilted at a certain angle, which can significantly reduce the downward speed of the liquid sodium compared to free fall, making it difficult for it to splash the liquid in the reactor 1, thereby effectively making the liquid remain on the inner wall of the reactor 1. The viscosity between the liquid sodium itself and the stainless steel is very small, and it will automatically flow down into the solution and mix with it to react.

[0034] Specifically, deceleration stripes are provided on the guide plate 26, and a fitting portion 262 is provided at the end of the guide plate 26. The outer end of the fitting portion 262 is curved and closely fits the inner wall of the reactor 1. When the liquid falls to any position of the fitting portion 262 at a set speed, it can slide down along the inner wall of the reactor 1.

[0035] Specifically, a pair of baffles 261 are fixedly connected to the guide plate 26 to effectively prevent the liquid from flowing down from both sides of the guide plate 26 .

[0036] It also includes a reduction motor 4, the output end of the reduction motor 4 is fixedly connected to a drive shaft 5, and the outer end of the drive shaft 5 is fixedly sleeved with multiple stirring blades 3 to help mix and stir and evenly diffuse heat.

[0037] Example 4: The difference between Example 4 and Example 3 is that the following technical features are added: The guide plate 26 is provided with an adjusting component, which includes a connecting pipe 23 connected to the bottom of the feed pipe 22. When the connecting pipe 23 descends, it drives the guide plate 26 to rotate to the second angle position, so that the liquid falls quickly.

[0038] A rotating rod is rotatably connected to the guide plate 26 , and both ends of the rotating rod are fixedly connected to the inner wall of the liquid outlet hole 25 .

[0039] When the liquid needs to flow down quickly, the feed pipe 22 is pressed, so that the connecting pipe 23 moves down and touches the guide plate 26, driving the guide plate 26 to rotate to a vertical angle, so that the liquid falls down.

[0040] The bottom of the connecting pipe 23 is rotatably connected to a resistance block 6, which is slidably connected to the top surface of the guide plate 26. During the downward movement of the connecting pipe 23, the guide plate 26 is driven to rotate. The outside of the feed pipe 22 is provided with friction grooves to increase friction damping.

[0041] Example 5: The difference between Example 5 and Example 4 is that the following technical features are added: Figure 7-10 A reciprocating component 7 is provided on the outside of the annular liquid storage tank 24. The reciprocating component 7 includes a driving screw 71. The external thread of the driving screw 71 is connected to a moving sleeve 72. The moving sleeve 72 is fixedly connected to the annular liquid storage tank 24.

[0042] In this embodiment, the annular liquid storage tank 24 is slidably connected to the inner wall of the reactor 1 .

[0043] In an embodiment further provided by the present invention, the connecting pipe 23 is a multi-stage telescopic tube, which includes multiple inner tubes and an outermost tube. A pair of clamping rings 73 are provided at the outer end of the outermost tube. The clamping rings 73 are responsible for clamping to the inside of the annular liquid storage tank 24. When the first clamping ring 73 is clamped to the inside of the annular liquid storage tank 24, the guide plate 26 is arranged at an angle. When the second clamping ring 73 is clamped to the inside of the annular liquid storage tank 24, the guide plate 26 is arranged vertically.

[0044] The clamping ring 73 is made of elastic material, and its elastic force is greater than the friction between the annular liquid storage tank 24 and the reactor 1. That is, when the annular liquid storage tank 24 moves, the clamping ring 73 keeps the outer part of the outermost tube and the annular liquid storage tank 24 relatively stationary.

[0045] The outer end of the driving screw rod 71 is fixedly sleeved with an electromagnet 74, and the outer end of the electromagnet 74 is sleeved with a pulley 75. The outer end of the driving shaft 5 is also sleeved with a pulley 75, and the outer part of the pulley 75 is sleeved with a transmission belt 76.

[0046] When pouring is required, the electromagnet 74 is turned on; when stirring is required, the electromagnet 74 is turned off and the reduction motor 4 is turned on in the fast gear mode for stirring.

[0047] The inner wall of the multi-stage telescopic tube is provided with a plurality of flow-blocking rings 77 arranged in sequence.

[0048] The flow blocking ring 77 is a plurality of inclined plates.

[0049] Optionally, the blocking ring 77 is an annular piece and is funnel-shaped with an inclined angle of 30-60 degrees, with the optimal angle being 45 degrees. It can not only effectively absorb the kinetic energy of the liquid, but also allow the liquid to flow normally.

[0050] When the second retaining ring 73 is clamped in the inside of the annular liquid storage tank 24, the guide plate 26 is arranged vertically. At this time, the reduction motor 4 is turned on and adjusted to the slow gear. Then the annular liquid storage tank 24 is slowly lowered to the lowest point, and then the liquid (such as solvent oil or other raw material liquid that needs to react) is poured. After the liquid falls to the bottom, the reduction motor 4 is driven in the reverse direction. The reduction motor 4 moves the annular liquid storage tank 24 upward, so that the lowest height of the liquid drop gradually increases. The liquid falls through the baffle ring 77, and the kinetic energy is reduced until it falls to the bottom of the reactor 1, thereby achieving the purpose of deceleration and reducing sputtering.

[0051] The above embodiments were all carried out in an inert atmosphere.

[0052] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A method for preparing trimethylaluminum, characterized in that: The steps are as follows: S1: Raw material preparation: solvent oil, aluminum powder, metallic sodium and methyl chloride; S2: reaction: the above raw materials are placed in the reactor in order to react; S3: Distilling to obtain a crude product: The crude trimethylaluminum is distilled out, and the remaining residual liquid in the kettle is discharged from the discharge port after cooling; S4: distillation: the crude trimethylaluminum product is transferred to a distillation kettle and heated for distillation under normal pressure; S5: Sampling and testing: Sample the above products for testing. If the test is qualified, the product will be canned. If the test is unqualified, repeat the subsequent actions of S3.

2. The method for preparing trimethylaluminum according to claim 1, wherein Said S2 comprises the following steps, S21: Pour a certain amount of solvent oil into the reactor; S22: Add aluminum powder, heat and evacuate, then gradually add methyl chloride to react; S23: When the amount of chloromethane added reaches the set value, the reaction is determined to be terminated; S24: The calculated metallic sodium is processed into a columnar shape through equipment, and the sodium is added to the reactor in batches according to the temperature of the reactor.

3. The method for preparing trimethylaluminum according to claim 1, wherein The residual liquid in S3 is finally taken to the hydrolysis station for hydrolysis and recovery of the solvent oil.

4. The method for preparing trimethylaluminum according to claim 4, wherein The crude trimethylaluminum in S3 is first temporarily stored in a crude product storage tank, and then transferred from the crude product transfer tank to the distillation kettle by nitrogen.

5. The method for preparing trimethylaluminum according to claim 5, wherein Said S4 comprises the following steps, S41, adjusting the distillation rate by setting the temperature of the distillation kettle heating circulator, receiving the fraction before the tower top temperature reaches the standard value into the pre-fraction receiving tank, and receiving the fraction after the tower top temperature reaches the standard value into the main distillate receiving tank; S42, the product in the front fraction receiving tank is transferred to the front fraction storage tank, and the product in the main fraction receiving tank is transferred to the main fraction storage tank; S42, when the distillation in the distillation kettle is completed, the system cools down and waits for the next batch of material transfer production.

6. The method for preparing trimethylaluminum according to claim 5, wherein The residual liquid remaining in the distillation kettle in S4 is transferred to the preparation kettle through an inner extension pipe for crude distillation separation, the trimethylaluminum in the residual liquid re-enters the crude product tank, and the solvent oil in the residual liquid is hydrolyzed and recovered.

7. A device for preparing trimethylaluminum, using the method for preparing trimethylaluminum according to any one of claims 1 to 6, characterized in that: The invention comprises a reactor, a feeding pipe is provided on the top of the reactor, a flow guide component is provided inside the reactor, the flow guide component comprises an annular liquid storage tank, a first liquid outlet is provided at the bottom of the annular liquid storage tank, and a flow guide plate is provided at the bottom of the annular liquid storage tank. The flow guide plate is arranged in an inclined manner and is used for allowing liquid sodium to flow down along the inner wall of the reactor during the falling process to reduce the falling speed.

8. The device for preparing trimethylaluminum according to claim 7, characterized in that: The guide plate is provided with an adjusting component, which includes a connecting pipe connected to the bottom of the feed pipe. During the descending process of the connecting pipe, the guide plate is driven to rotate to the second angle position to make the liquid fall quickly.

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