Preparation device and preparation process of electronic-grade hexamethyldisilazane

Abstract

The invention provides a preparation device and a preparation process of electronic-grade hexamethyldisilazane. The preparation device comprises a synthesis reactor, the desalting device is connected with the discharge hole of the synthesis reactor and is used for crystallizing and desalting NH4Cl contained in the synthesis reaction liquid discharged by the synthesis reactor; the coarse distillation tower is used for distilling and separating low-boiling-point components contained in the filtrate obtained by the desalting device; and the rectifying tower device is connected with the outlet end at the bottom of the crude distillation tower and is used for further rectifying and purifying the synthetic reaction liquid purified by the crude distillation tower so as to obtain the electronic-grade hexamethyldisilazane. According to the scheme, a noble metal catalyst is not needed in the hexamethyldisilazane synthesis process, raw materials can be recycled, an inert solvent is not used, and a high-shear reactor and a cryogenic desalting technology are adopted, so that a product is prevented from being wrapped by salt particles.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of hexamethyldisilazane, and specifically relates to a preparation device and a preparation process of electronic-grade hexamethyldisilazane. Background Art

[0002] Hexamethyldisilazane, also known as hexamethyldisilazane, abbreviated as HMDS; is mainly used as an adhesive aid for photoresists in semiconductor manufacturing. In addition, during the development process, it can effectively inhibit pattern shifting because it enhances the adhesion between the photoresist and the substrate.

[0003] In the related prior art, there are three main methods of synthesis: catalyst method, synthesis method using hexamethyldisiloxane as raw material and solvent method. 1. The catalyst method generally uses precious metals such as Pt and Pd as catalysts to react TMS with NH3 in a gaseous state at 160°C to obtain the product. The catalyst method mostly uses precious metals such as Pt and Pd as catalysts, has strict requirements on equipment and requires a large investment; 2. The synthesis method using hexamethyldisiloxane as raw material requires reaction with concentrated sulfuric acid to generate solid trimethylsilylsulfonic anhydride, and then trimethylsilylsulfate is prepared by ammoniation in the presence of a sedimentation agent or solvent. The process operation is complicated and cumbersome, and the treatment of the three wastes is difficult. 3. The solvent method uses TMS (trimethylchlorosilane) as a raw material, reacts with ammonia in the presence of an inert solvent, and the reactants are centrifuged and distilled to remove the inert solvent to obtain the product. The reaction is an exothermic reaction, and a reasonable inert organic solvent must be used as a diluent. The separation of the product affects the yield of the reaction. A certain concentration of NaOH solution is added to the reaction mixture under stirring until NH4Cl is completely dissolved, and then the mixture is allowed to stand for stratification. The upper layer is a mixture of the diluent and the product, and the lower layer is a NaCl solution. The defects of the solvent method are as follows: first, the output of the raw material TMS is small; second, the ammonium chloride particles produced will wrap the product; third, the amount of inert solvent used is large, and separation is difficult; fourth, production is mostly intermittent operation, which is inefficient and occupies a large space. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the problems existing in the above-mentioned prior art and to provide a preparation device and a preparation process of electronic grade hexamethyldisilazane. The process of synthesizing hexamethyldisilazane in this scheme does not require a precious metal catalyst, the raw materials can be recycled, no inert solvent is used, and a high shear reactor and deep cold desalination technology are used to avoid salt particles from wrapping the product.

[0005] One of the purposes of the present invention is to provide a device for preparing electronic grade hexamethyldisilazane, comprising a synthesis reactor, wherein the inlet of the synthesis reactor comprises a first raw material supply pipeline and a second raw material supply pipeline, wherein the first raw material supply pipeline is used to supply raw material ammonia; the second raw material supply pipeline is used to supply raw material trimethylchlorosilane;

[0006] A desalting device, connected to the discharge port of the synthesis reactor, for crystallizing and filtering the NH4Cl contained in the synthesis reaction liquid discharged from the synthesis reactor to remove salt;

[0007] A crude distillation tower is used to distill and separate the filtrate after filtering and desalting the synthetic reaction liquid obtained by the desalting device;

[0008] The distillation tower device is connected to the bottom outlet of the crude distillation tower and is used for further distilling and purifying the synthetic reaction liquid after preliminary purification by the crude distillation tower to obtain electronic grade hexamethyldisilazane.

[0009] As a preferred embodiment, the material inlet of the crude distillation tower is connected to the outlet of the desalting device, and the top pipeline I is connected to the inside of the synthesis reactor tank to deliver the low-boiling components distilled from the crude distillation tower into the synthesis reactor through the top pipeline I.

[0010] As a preferred embodiment, the distillation tower device includes a first distillation tower and a second distillation tower, the feed inlet of the first distillation tower is connected to the crude product outlet at the bottom of the crude distillation tower, the bottom product outlet of the first distillation tower is connected to the material inlet of the second distillation tower, and the top outlet of the second distillation tower is connected to the product tank through a condenser IV.

[0011] As a preferred embodiment, it further comprises an impurity removal device, wherein the material inlet of the impurity removal device is connected to the crude product outlet at the bottom of the crude distillation tower, and the material outlet of the impurity removal device is connected to the material inlet of the first distillation tower.

[0012] As a preferred embodiment, the first raw material pipeline is provided with a condenser I, and the condenser I is used to cool the raw material ammonia that is about to enter the synthesis reactor. The second raw material pipeline is provided with a condenser II, and the condenser II is used to cool the raw material trimethylchlorosilane that is about to enter the synthesis reactor.

[0013] As a preferred embodiment, the first distillation tower comprises a top outlet, a bottom outlet and a material inlet arranged between the top outlet and the bottom outlet, the top outlet of the first distillation tower is connected to the material inlet of the condenser III through the top pipeline II; the material outlet of the condenser III is connected to the reflux port of the tower body through the reflux pipeline I, and the material outlet of the condenser III is also connected to the low-boiling component tank through the drainage pipeline, the second distillation tank comprises a top outlet, a bottom outlet and a material inlet arranged between the top outlet and the bottom outlet, the top pipeline III of the second distillation tank is connected to the material inlet of the condenser IV, the material outlet of the condenser IV is connected to the reflux port of the tower body through the reflux pipeline II, and the material outlet of the condenser IV is also connected to the product tank through the product pipeline.

[0014] The second object of the present invention is to provide a method for preparing the electronic grade hexamethyldisilazane preparation device according to any one of the above items, comprising the following steps:

[0015] Step 1, adding raw material trimethylchlorosilane into a synthesis reactor, and then adding raw material ammonia into the synthesis reactor in proportion, reacting under stirring conditions, the pressure range in the synthesis reactor is 10-50KPa, the reaction temperature range is -40 to 20°C, and the reaction time is 1-3h;

[0016] Step 2: After the reaction is completed, the synthetic reaction liquid enters a desalting device for filtration to remove NH4Cl and obtain a filtrate;

[0017] Step 3, sending the filtrate obtained in step 2 to a crude distillation tower, extracting low-boiling-point components from the top of the crude distillation tower, and extracting a crude product from the bottom of the crude distillation tower;

[0018] Step 4: After filtering, the crude product at the bottom of the tower obtained in step 3 enters the first distillation tower for purification. The low-boiling point components are evaporated at the top of the first distillation tower. The primary distillation and purification product at the bottom of the first distillation tower enters the material inlet of the second distillation tower for secondary distillation and purification. The electronic grade hexamethyldisilazane is purified and separated at the top of the second distillation tower and sent to the product tank.

[0019] As a preferred embodiment, the mass ratio of raw material trimethylchlorosilane to raw material ammonia is 24-9:1.

[0020] As a preferred solution, the raw materials trimethylchlorosilane and ammonia are respectively cooled and pre-cooled by condensers before entering the synthesis reactor.

[0021] As a preferred embodiment, the reflux ratio of the first distillation tower and the second distillation tower is 4:1-6:1.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] First, the present invention provides a device for preparing electronic-grade hexamethyldisilazane. By arranging a desalting device at the outlet of the reaction liquid of the synthesis reactor, NH4Cl can be effectively separated to avoid ammonium chloride particles wrapping the product and prevent the subsequent influence on the purity of the product. A crude distillation tower is used after the desalting device to preliminarily purify the material, and the low-boiling trimethylchlorosilane extracted from the top of the tower can be directly returned to the synthesis reactor, and the material can be recycled and reused; by arranging an impurity removal device after the crude distillation tower, the filter membrane of the impurity removal device has a molecular screening effect and the selectivity of the adsorption material, and can effectively remove impurities and purify the target substance. Then it enters the first and second distillation towers for joint purification, and finally extracts at the top of the second distillation tower to obtain electronic-grade HMDS.

[0024] Second, the present invention also provides a method for preparing electronic-grade hexamethyldisilazane, which is organically combined with the preparation device of the above-mentioned specific structure. In this scheme, the raw material enters the synthesis reactor after cooling, and the reaction synthesis liquid enters the deep cold filtration drying desalination device for filtration. The liquid-solid separation and deep cold desalination process are adopted to effectively separate the trace salt in the product to a great extent, solving the problem of the difficulty of solid-liquid separation of the reaction product in the existing process and the problem of the product containing salt particles. The filtrate is purified by crude distillation + membrane adsorption + rectification to obtain the product, and the product purity reaches the electronic grade standard. In the preparation process of this scheme, no inert solvent is used, and no impurities are introduced in the product manufacturing process, which solves the problem of pollution caused by the use of solvents and the difficulty of product separation and purification; the synthesis process of HMDS in this scheme does not require precious metal catalysts, which solves the problem of using precious metal catalysts. This scheme realizes fully automatic and continuous environmentally friendly production through synthesis + deep cold filtration + crude distillation + impurity removal + rectification. The synthesis reaction liquid adopts membrane filtration process technology to solve the problem of difficult separation of impurity elements B, AL, Ca, etc. in the preparation process of electronic-grade products. The product purity can reach 7N, and the content of a single metal impurity is less than 1ppb. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a flow chart of the preparation device of the present invention;

[0027] Markings in the figure: 1. synthesis reactor, 2. desalting device, 3. crude distillation tower, 4. impurity removal device, 5. first distillation tower, 6. second distillation tower, 7. top pipeline I, 8. top pipeline II, 9. condenser I, 10. condenser II, 11. condenser III, 12. condenser IV, 13. pump I, 14. pump II, 15. pump III, 16. low boiling component tank, 17. product tank, 18. high boiling component tank, 19. first raw material supply pipeline, 20. second raw material supply pipeline, 21. top pipeline III, 22. reflux pipeline I, 23. reflux pipeline II. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and beneficial effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0029] In addition, in order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. Those skilled in the art should understand that the present invention can also be implemented without certain specific details. In other embodiments, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present invention.

[0030] like Figure 1 As shown, this embodiment provides a preparation device for electronic grade hexamethyldisilazane, including a synthesis reactor 1 and a desalting device 2. The feed port of the synthesis reactor 1 is respectively connected to a first raw material supply pipeline 19 for supplying raw material ammonia and a second raw material supply pipeline 20 for supplying trimethylchlorosilane. The first raw material supply pipeline 19 is provided with a condenser I9, which is used to cool the raw material ammonia from the ammonia bottle to below about -30°C before entering the synthesis reactor 1 to liquid ammonia before entering the synthesis reactor 1. The second raw material supply pipeline 20 is provided with a condenser II10, which is used to cool the trimethylchlorosilane to below -30°C before entering the synthesis reactor 1; in the subsequent preparation embodiments of this scheme, trimethylchlorosilane can be contained in a 20L raw material tank, and the material of the raw material tank is an internally polished 316 stainless steel material; the bottom of the synthesis reactor 1 is provided with a discharge port, and the synthesis reactor 1 is connected to the material inlet of the desalting device 2 through the bottom discharge port, and the desalting process of the synthesis reaction liquid is realized through the desalting device 2. The filtrate of the synthetic reaction liquid filtered by the desalting device 2 can be subjected to post-process distillation purification to obtain the final product electronic grade hexamethyldisilazane. In the subsequent preparation process embodiment, the condenser I9 and the condenser II10 are both made of S31603, the heat exchange area is 0.04㎡, the tube side / shell side design applicable temperature range is 60 / -40℃, and the condenser I9 and the condenser II10 are cooled by a high and low temperature integrated cooling and heating machine, and can exchange heat through a low temperature oil medium.

[0031] In a typical embodiment of the present invention, the volume of the synthesis reactor 1 used in the subsequent preparation embodiment is 5L, and its material is 316L stainless steel, the temperature design range is +200℃ to -30℃, and the applicable working pressure of the synthesis reactor 1 is -0.05-1.6Mpa; the synthesis reactor 1 adopts magnetic stirring and automatic temperature control, has high shear stirring ability and has jacket or coil heat exchange function; specifically, the inlet and outlet ends of the jacket or coil are connected to the heat exchange medium interface of the high and low temperature cold and hot integrated machine to achieve heat exchange, and the synthesis reactor 1 adopts a detachable structure; since the reaction process will release a lot of heat, in the subsequent preparation embodiment, the synthesis reactor 1 controls the reaction temperature through the high and low temperature cold and hot integrated machine. It should be pointed out that the synthesis reactor 1 can increase the volume of the synthesis reactor 1 according to the feed amount of the material. The desalination device 2 adopts a bag filter, which includes a double-layer bag filter system with a filtration accuracy of 2-4μm and an accuracy of 0.05-0.5μm. The bag filter used in the subsequent preparation process embodiment has a volume of 5L.

[0032] In the present scheme, the preparation device also includes a crude distillation tower 3, an impurity removal device 4 and a distillation tower device. The crude distillation tower 3 includes a top outlet, a bottom outlet and a feed port arranged between the top outlet and the bottom outlet. The inlet of the crude distillation tower 3 is connected to the material outlet end of the desalination device 2. In an embodiment without the attached figure, the desalination device 2 is filtered and the filtrate is stored in a filtrate storage tank (not shown in the figure). The material inlet of the crude distillation tower 3 is connected to the outlet end of the filtrate storage tank for continuous supply of raw materials to the crude distillation tower 3. The top outlet of the crude distillation tower 3 is connected to the interior of the synthesis reactor 1 through the top pipeline Ⅰ7. Specifically, the top pipeline Ⅰ7 of the crude distillation tower 3 can be connected to the upper empty area in the tank body of the synthesis reactor 1. A condenser V (not shown in the figure) is arranged on the top pipeline Ⅰ7. The inlet and outlet of the material pipeline of the condenser V (cooled with 7°C water) are connected to the top pipeline Ⅰ7, so that a part of the separated low-boiling point components discharged from the top pipeline Ⅰ7 are returned to the interior of the synthesis reactor 1 for recycling and reaction, thereby improving the overall yield and achieving cost savings. The other part is returned to the reflux port of the crude distillation tower 3 through the reflux pipeline (not shown in the figure) to participate in separation and purification again. Alternatively, in another embodiment not shown in the figure, the tower top pipeline I7 is connected to a low-boiling point storage tank (not shown) through a condenser V for temporary storage and collection of low-boiling point substances. The low-boiling point storage tank is used to be connected to the synthesis reactor 1, so as to transfer the low-boiling point components collected by the crude distillation tower 3 to the synthesis reactor 1 in a planned manner for recovery and utilization of the low-boiling point components, and another part of the low-boiling point substances enter the reflux port of the tower body through the reflux pipeline. Taking the crude distillation tower 3 used in the subsequent preparation process embodiment as an example, the crude distillation tower 3 uses non-polished θ filler inside, with a height of 2M, a theoretical plate number of 40, a feed rate of 0.5L / h, a pressure of 10-30KPa, and a reflux ratio of 4:1-6:1. The reflux pipeline and reflux port of the crude distillation tower 3 are not shown in the figure, and its reflux port is arranged above the feed port of the crude distillation tower 3; the impurity removal device 4 contains a polytetrafluoroethylene (PTFE) impurity removal filter membrane, and uses multiple functional groups to combine and filter for impurity removal, and its volume is 3L. The feed port of the impurity removal device 4 is connected to the tower bottom product outlet of the crude distillation tower 13 through pump I 13. The filter membrane of the impurity removal device 4 has a molecular screening effect and selectivity of adsorption materials, which can effectively remove impurities and purify target substances. The discharge port of the impurity removal device 4 is connected to the feed port of the distillation tower device through pump II 14, and the filtrate is sent to the distillation tower device through the pumping action of pump II 14 to achieve distillation and purification.

[0033] In this embodiment, the distillation tower device adopts a two-stage distillation purification device, including a first distillation tower 5 and a second distillation tower 6, wherein the first distillation tower 5 includes a top outlet, a bottom outlet and a material inlet arranged between the top outlet and the bottom outlet, the material inlet of the first distillation tower 5 is connected to the filtrate outlet of the impurity removal device 4 through a pump II 14, the top pipeline II 8 of the first distillation tower 5 is connected to the material inlet of the condenser III 11, the function of the condenser III 11 is to condense the low-boiling point components separated from the top of the first distillation tower 5, and the material outlet of the condenser III 11 is connected to the reflux port of the tower body of the first distillation tower 5 through a reflux pipeline I 22, and the material outlet of the condenser III 11 (7°C water cooling) is also connected to the low-boiling component tank 16 through a discharge pipeline 24, so that a part of the low-boiling point components are separated and enter the low-boiling component tank 16, and the other part returns to the inside of the tower body through the reflux port to continue to participate in the distillation process. It should be pointed out that the low-boiling component in the low-boiling component tank 16 still contains a certain amount of unreacted raw materials, which can be recycled and reused in the subsequent preparation process to further save raw materials and reduce production costs. In the subsequent preparation example, the first distillation tower 5 is polished, and polished θ filler is used inside, the tower body height is 2M, the theoretical number of plates is 40, the feed rate is 0.5L / h, the pressure is -95KPa to 0.5MPa, and the reflux ratio is controlled within the range of 4:1-6:1. The second distillation tower 6 includes a tower top outlet, a tower bottom outlet, and a material inlet arranged between the tower top outlet and the tower bottom outlet, wherein the material inlet of the second distillation tower 6 is connected to the product outlet at the bottom of the tower body of the first distillation tower 5 through a pump III 15, and the crude product after the primary distillation and purification is pumped to the second distillation tower 6 for further distillation and purification of the product after the primary distillation and purification.

[0034] In this scheme, the top outlet of the second distillation tower 6 is connected to the working fluid inlet of the condenser IV12 through the top pipeline III21. The function of the condenser IV12 is to condense the product components separated from the top of the second distillation tower 6. The material outlet of the condenser IV12 (7°C water cooling) is connected to the tower reflux port of the second distillation tower 6 through the reflux pipeline II23. The material outlet of the condenser IV12 is also connected to the product tank 17 through the product pipeline 25, so that part of the high-purity product enters the product tank 17, and the other part returns to the inside of the tower body to continue to participate in the distillation process. The second distillation tower 6 is polished inside, and polished θ filler is used inside. The tower height is 2M, the theoretical number of plates is 40, the feed rate is 0.5L / h, the pressure is -95KPa to 0.5MPa, and the reflux ratio is controlled within the range of 4:1-6:1. The high boiling point component outlets of the tower bottoms of the first distillation tank 5 and the second distillation tank 6 are connected to the high boiling point component tank 18, so that the high boiling point components are discharged into the high boiling point component tank 18 for storage. Since the high boiling point components are still rich in a certain amount of products, they can be recycled and reused in the subsequent production and preparation process to further improve the product yield and reduce the production cost.

[0035] In this solution, the pipes and equipment used in the above-mentioned preparation device are all made of internally polished stainless steel, among which the first distillation tower 5 and the second distillation tower 6 are made of internally polished 316 stainless steel; the crude distillation tower 3, the first distillation tower 5 and the second distillation tower 6 are all packed towers, and the packing used is stainless steel θ ring packing, triangular spiral packing, glass spring packing, etc.; preferably, stainless steel θ ring packing is used. In this solution, the deep cold filtration and drying desalination device 2 used is an automatic self-cleaning filter, which is a multi-functional device that can integrate pulping, filtering, washing and drying functions.

[0036] The present invention also provides a preparation method using the above-mentioned electronic-grade hexamethyldisilazane preparation device, comprising the following steps:

[0037] Step 1, add trimethylchlorosilane into the synthesis reactor 1, then add liquid ammonia into the synthesis reactor 1 in proportion, stir and react, the pressure in the synthesis reactor 1 is controlled at 10-50KPa, the reaction temperature is controlled at -40 to 20°C, and the reaction time is 1-3h;

[0038] In this step, the purity of the raw material high-purity ammonia is 99.9999%; the purity of the raw material trimethylchlorosilane is ≥99.5%, and the trimethylchlorosilane is cooled and added into the synthesis reactor 1; the raw material ammonia from the ammonia bottle is cooled into liquid ammonia through the condenser I9, and low-temperature liquid ammonia is added according to the proportion. In the synthesis reactor 1, the materials are stirred for reaction, the synthesis reaction pressure is controlled at 10-50KPa, the reaction temperature is controlled at -40 to 20°C, and the preferred reaction temperature is -20 to 20°C; the reaction time is 1-3h, and the preferred reaction time is 2-3h;

[0039] Step 2: After the reaction is completed, the synthetic product enters the desalting device 4 for washing and filtration to remove NH4Cl and obtain the filtrate after the synthetic reaction;

[0040] In this step, NH4Cl is generated during the reaction in the synthesis reactor 1, and the synthetic product enters the deep cold filtration drying and desalting device for washing and filtration, and the NH4Cl is removed to obtain the filtrate of the synthetic reaction liquid for further separation and purification. This scheme adopts a positive pressure filtration method, and specifically, nitrogen can be introduced into the synthesis reactor 1 for pressure filtration.

[0041] Step 3, sending the filtrate of step 2 into a crude distillation tower 3, extracting low-boiling-point components from the top of the crude distillation tower 3, and extracting a crude product from the bottom of the crude distillation tower 3;

[0042] In this step, the filtered and washed synthetic material is sent to the crude distillation tower 3, a part of the low-boiling material containing trimethylchlorosilane is taken out from the top of the tower and returned to the synthesis reactor 1, and the other part is returned to the inside of the tower body of the crude distillation tower 3 through the reflux port, and the unreacted material can be returned to the synthesis reactor 1 through the top pipeline Ⅰ7 to realize recycling and reuse;

[0043] Step 4: After the crude product at the bottom of the tower obtained in step 3 is filtered out by the impurity removal device 4, it enters the first distillation tower 5 for purification. The top pipeline II8 of the first distillation tower 5 evaporates the crude fraction and enters the low-boiling component tank 16. The crude product at the bottom of the first distillation tower 5 enters the raw material inlet of the second distillation tower 6 for secondary purification, and the electronic grade hexamethyldisilazane is distilled from the top pipeline III21 and sent to the product tank 17.

[0044] In this step, the obtained crude product HMDS passes through the impurity removal device 4 and then enters the first distillation tower 5 and the second distillation tower 6 for joint purification, and electronic grade HMDS is obtained at the top of the second distillation tower 6, and finally enters the product tank 7 of high-purity products. The low-boiling components and high-boiling components separated by the first distillation tower 5 and the second distillation tower 6 can be further recovered and reused.

[0045] In this scheme, the reaction equation is as follows:

[0046] 2(CH3)3SiCl+3NH3→((CH3)3Si)2NH+2NH4Cl

[0047] The whole preparation process of the present invention is as follows: raw materials trimethylchlorosilane and raw material ammonia are cooled by condenser I9 and condenser II10 and then enter into synthesis reactor 1, and then enter into deep cold filtering drying desalting device 2 after synthesis reaction, and the liquid material after synthesis reaction after filtering and washing enters into crude distillation tower 3, and the low boiling point component rich in trimethylchlorosilane at the top of crude distillation tower 3 can be returned to synthesis reactor 1 for application, and the crude product rich in HMDS discharged from the bottom enters into first distillation tower 5 after passing through impurity removal device 4, and the material after synthesis reaction is purified and distilled by first distillation tower 5 and second distillation tower 6 jointly, and the product purity reaches electronic grade standard (component 99.99%, single metal impurities such as Li, Na, Mg, AL, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Zr, Mo, Pd, Ag, Cd, Sn, Ba, Ta, W, Pt, Au, Pb are less than 1 ppb), and the electronic grade product enters into distillation product tank 17.

[0048] The preparation process of this scheme is mainly: trimethylchlorosilane and ammonia materials are mixed and reacted efficiently, liquid-solid separation and deep cold desalination, crude distillation and purification, combined impurity removal, and continuous distillation to produce high-purity products. The key devices such as synthesis reactor, crude distillation tower, impurity removal device, distillation tower, storage tank, etc. are required to complete the reaction product. This scheme does not add inert solvents, which can avoid separation difficulties and impurity introduction during product preparation. After cooling, the raw materials enter the synthesis reactor 1, the reaction synthesis liquid enters the deep cold filtration and drying desalination device 4 for filtration, and the filtrate is purified by crude distillation + membrane adsorption + distillation to obtain the product, and the product purity reaches the electronic grade standard. This scheme adopts synthesis + deep cold filtration + crude distillation + impurity removal + distillation combined purification to achieve fully automatic and continuous environmentally friendly production. This scheme is a production process that can achieve continuous production, which is suitable for large-scale production. The process technology and device structure are reliable in operation, and can effectively reduce production costs, with high economic benefits and environmental protection effects.

[0049] The present invention is further described in detail below with reference to the accompanying drawings and through specific embodiments:

[0050] Example 1

[0051] Step 1: Use high-purity nitrogen to replace the feed pipeline of the synthesis reactor 1 and the interior of the synthesis reactor 1 to remove the internal oxygen and moisture, and detect the water oxygen value: the water oxygen content is ≤50ppm, and it is ready for use after reaching the replacement standard;

[0052] Step 2: Cool the trimethylchlorosilane raw material to below -30°C and add it to the synthesis reactor 1, start the agitator speed at 200r / min, and reduce the material temperature in the synthesis reactor 1 to -40°C; the ammonia gas is cooled to below -30°C to be liquid ammonia and then enters the synthesis reactor 1, the reaction time is 2h, and the high and low temperature integrated machine controls the reaction temperature in the synthesis reactor 1 to be in the range of -20-20°C (the synthesis reaction is an exothermic reaction, and it will fluctuate within a certain temperature range during the reaction process), and the reaction pressure range is controlled in the range of 10-50Kpa;

[0053] Step 3, after the synthesis reaction is completed, the material begins to be filtered (positive pressure filtration, which can be performed by introducing a certain pressure of nitrogen into the synthesis reactor 1 for pressure filtration) and washed (using raw material trimethylchlorosilane for washing). After the filter cake is washed 3 times, the three-in-one solid discharge port is automatically opened, and the agitator of the desalination device 2 sends the filter cake out and receives it in a sealed bag or a storage container for salt.

[0054] Step 4: Collect the filtrate mixture, measure it and temporarily store it in a specific container or storage tank, detect the hexamethyldisilazane content in the filtrate, and calculate the reaction yield.

[0055] Embodiment 2-4

[0056] The other conditions are the same as those in Example 1, except that the feeding amounts of trimethylchlorosilane and raw material high-purity ammonia gas in Example 1 are changed.

[0057] Table 1 is the preparation process data of Examples 1-4

[0058]

[0059]

[0060] As can be seen from the table above, after adjusting the raw material mass ratio, the HDMS content and the actual yield in the synthetic reaction filtrate first increased and then decreased through detection. In Example 3, the HDMS content reached the highest 19.05%, and after calculation, the actual yield reached 55.03%. Therefore, Example 3 is a better raw material ratio, and it can be seen that the raw material ratio of the two has a greater impact on the reaction yield.

[0061] Example 5

[0062] This embodiment provides a method for separating and purifying a synthetic reaction filtrate, comprising the following steps:

[0063] Step 1: The filtrate obtained in Example 3 is sent to a positive pressure crude distillation tower 3 for purification, the top pressure of the crude distillation tower 3 is controlled at 10-30 KPa, the top temperature is controlled at 60°C, and the trimethylchlorosilane in the low-boiling point component at the top of the tower is condensed and returned to the synthesis reactor 1 (or a temporary storage tank) for temporary storage for reuse, and the reflux ratio (reflux flow rate: top extraction flow rate) of the crude distillation tower 3 is controlled to be 4:1.

[0064] Step 2: filtering the product obtained in step 1 through a filter device of a membrane 4 of a removal device to obtain a filtrate;

[0065] Step 3: Send the filtrate to the distillation tower device for joint purification, wherein the top pressure of the first distillation tower 5 is controlled at -95KPa, the top temperature of the tower is controlled at 0°C, and the reflux ratio is 4:1; after removing the high and low boiling components and metal impurities, the once purified product enters the second distillation tower 6. The second distillation tower 6 controls the top pressure at -95KPa, the top temperature of the tower is controlled at 0°C, and the reflux ratio is 4:1; after removing the high and low boiling components and metal impurities, the distillation product HMDS is collected at the top of the tower; the HMDS product enters the product tank 17.

[0066] Comparative Example 1

[0067] The other conditions are the same as those in Example 5, except that: Comparative Example 1 does not include step 2, but directly feeds the product material after passing through the crude distillation tower 3 into the distillation tower device. The specific steps are as follows:

[0068] Step 1: The filtrate obtained in Example 3 is sent to a positive pressure crude distillation tower 3 for purification, the top pressure of the crude distillation tower 3 is controlled at 10-30 KPa, the top temperature is controlled at 60°C, and the trimethylchlorosilane in the low-boiling point component at the top of the tower is condensed and returned to the synthesis reactor 1 (or a temporary storage tank) for temporary storage for reuse, and the reflux ratio (reflux flow rate: top extraction flow rate) of the crude distillation tower 3 is controlled to be 4:1.

[0069] Step 2: The product obtained in step 1 is directly sent to the distillation tower device for joint purification, wherein the top pressure of the first distillation tower 5 is controlled at -95KPa, the top temperature of the tower is controlled at 0°C, and the reflux ratio (reflux flow rate: top extraction flow rate) is 4:1; after removing high and low boiling components and metal impurities, the product after one extraction enters the second distillation tower 6. The second distillation tower 6 controls the top pressure at -95KPa, the top temperature of the tower is controlled at 0°C, and the reflux ratio is 4:1; after removing high and low boiling components and metal impurities, the distillation product HMDS is collected at the top of the tower; the HMDS product enters the product tank 17.

[0070] The results of GC-MS testing of the product are shown in Table 2 below. The content of individual metal impurities in the product obtained in Example 5 is less than 1 ppb, TMI≤3 ppb, and the product purity meets the standard; Example 5 is better than Comparative Example 1, which shows that the crude distillation + membrane adsorption + distillation purification used in this scheme can effectively remove high and low boiling components and impurities in the reaction product and meet the target product quality requirements.

[0071] Table 2 is the test results of Example 5 and Comparative Example 1

[0072]

[0073]

[0074] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A device for preparing electronic grade hexamethyldisilazane, characterized in that: A synthesis reactor is included, wherein the inlet of the synthesis reactor includes a first raw material supply pipeline and a second raw material supply pipeline, wherein the first raw material supply pipeline is used to supply raw material ammonia; and the second raw material supply pipeline is used to supply raw material trimethylchlorosilane; A desalting device, connected to the discharge port of the synthesis reactor, for crystallizing and filtering the NH4Cl contained in the synthesis reaction liquid discharged from the synthesis reactor to remove salt; A crude distillation tower is used to distill and separate the filtrate after filtering and desalting the synthetic reaction liquid obtained by the desalting device; The distillation tower device is connected to the bottom outlet of the crude distillation tower and is used for further distilling and purifying the synthetic reaction liquid after preliminary purification by the crude distillation tower to obtain electronic grade hexamethyldisilazane.

2. The preparation device of electronic grade hexamethyldisilazane according to claim 1, characterized in that: The material inlet of the crude distillation tower is connected to the outlet of the desalting device, and the top pipeline I is connected to the inside of the synthesis reactor tank, which is used to send the low-boiling components distilled from the crude distillation tower into the synthesis reactor through the top pipeline I.

3. The preparation device of electronic grade hexamethyldisilazane according to claim 1, characterized in that: The distillation tower device includes a first distillation tower and a second distillation tower, the feed inlet of the first distillation tower is connected to the crude product outlet at the bottom of the crude distillation tower, the bottom product outlet of the first distillation tower is connected to the material inlet of the second distillation tower, and the top outlet of the second distillation tower is connected to the product tank through a condenser IV.

4. The device for preparing electronic grade hexamethyldisilazane according to claim 3, characterized in that: It also includes an impurity removal device, the material inlet of the impurity removal device is connected to the crude product outlet at the bottom of the crude distillation tower, and the material outlet of the impurity removal device is connected to the material inlet of the first distillation tower.

5. The device for preparing electronic grade hexamethyldisilazane according to claim 1, characterized in that: The first raw material pipeline is provided with a condenser I, which is used to cool the raw material ammonia that is about to enter the synthesis reactor. The second raw material pipeline is provided with a condenser II, which is used to cool the raw material trimethylchlorosilane that is about to enter the synthesis reactor.

6. The device for preparing electronic grade hexamethyldisilazane according to claim 3, characterized in that: The first distillation tower comprises a tower top outlet, a tower bottom outlet and a material inlet arranged between the tower top outlet and the tower bottom outlet. The tower top outlet of the first distillation tower is connected to the material inlet of the condenser III through the tower top pipeline II; the material outlet of the condenser III is connected to the reflux port of the tower body through the reflux pipeline I, and the material outlet of the condenser III is also connected to the low-boiling component tank through the drainage pipeline. The second distillation tank comprises a tower top outlet, a tower bottom outlet and a material inlet arranged between the tower top outlet and the tower bottom outlet. The tower top pipeline III of the second distillation tank is connected to the material inlet of the condenser IV, the material outlet of the condenser IV is connected to the reflux port of the tower body through the reflux pipeline II, and the material outlet of the condenser IV is also connected to the product tank through the product pipeline.

7. A method for preparing an electronic grade hexamethyldisilazane preparation device, characterized in that: The steps include: Step 1, adding raw material trimethylchlorosilane into a synthesis reactor, and then adding raw material ammonia into the synthesis reactor in proportion, reacting under stirring conditions, the pressure range in the synthesis reactor is 10-50KPa, the reaction temperature range is -40~20°C, and the reaction time is 1-3h; Step 2: After the reaction is completed, the synthetic reaction liquid enters a desalting device for filtration to remove NH4Cl and obtain a filtrate; Step 3, sending the filtrate obtained in step 2 to a crude distillation tower, extracting low-boiling point components from the top of the crude distillation tower, and extracting a crude product from the bottom of the crude distillation tower; Step 4: After filtering, the crude product at the bottom of the tower obtained in step 3 enters the first distillation tower for purification. The low-boiling point components are evaporated at the top of the first distillation tower. The primary distillation and purification product at the bottom of the first distillation tower enters the material inlet of the second distillation tower for secondary distillation and purification. The electronic grade hexamethyldisilazane is purified and separated at the top of the second distillation tower and sent to the product tank.

8. The method for preparing the electronic grade hexamethyldisilazane preparation device according to claim 7, characterized in that: The mass ratio of raw material trimethylchlorosilane to raw material ammonia is 24-9:

1.

9. The method for preparing the electronic grade hexamethyldisilazane preparation device according to claim 7, characterized in that: The raw material trimethylchlorosilane and the raw material ammonia are respectively cooled and pre-cooled by a condenser and then enter the synthesis reactor.

10. The method for preparing the electronic grade hexamethyldisilazane preparation device according to claim 7, characterized in that: The reflux ratio of the first distillation tower to the second distillation tower is 4:1-6:1.

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