System and method for preparing tetramethylsilane

Abstract

The invention discloses a system and method for preparing tetramethylsilane, wherein the system for preparing tetramethylsilane comprises a raw material tank, a distillation device, an adsorption device and a sub-boiling distillation tower, wherein the raw material tank is used to hold a mixture containing tetramethylsilane, the distillation device comprises a first distillation tower and a second distillation tower, the first distillation tower is connected to the raw material tank and the second distillation tower, the first distillation tower is used to remove chloroalkanes in the mixture to form a first mixture, the second distillation tower is used to remove part of the small molecule alkanes in the first mixture to form a second mixture, the adsorption device is connected to the second distillation tower to remove the small molecule alkanes and olefins in the second mixture and form a third mixture, and the sub-boiling distillation tower is connected to the adsorption device to purify the third mixture to obtain tetramethylsilane. The tetramethylsilane prepared by the system for preparing tetramethylsilane of the invention has high purity and low production cost.

Description

Technical Field

[0001] The invention relates to the technical field of tetramethylsilane preparation, and in particular to a tetramethylsilane preparation system and a tetramethylsilane preparation method. Background Art

[0002] In the production of organosilicon, methyl chloride reacts with metallic silicon to form methylchlorosilane. Methylchlorosilane is the most important monomer for the preparation of organosilicon polymers, and its usage in the organosilicon industry accounts for more than 90% of all organosilicon monomer usage. In the process of synthesizing methylchlorosilane, a large amount of low-boiling substances are produced, the main components of which are tetramethylsilane and methylchlorosilane. It also contains a small amount of impurities such as alkanes, olefins, and halogenated hydrocarbons.

[0003] In the related art, there are two main methods for preparing tetramethylsilane from low boiling points:

[0004] One is to remove compounds containing Si-Cl bonds in low-boiling products through a hydrolysis process, and then perform molecular sieve adsorption to remove impurities such as alkanes, olefins, chloroalkanes, and trimethylsilane to prepare high-purity tetramethylsilane.

[0005] The second is to remove compounds such as chlorosilane or methylchlorosilane in low-boiling products through a hydrolysis process, and then perform filtration and liquid separation treatment, and perform ordinary distillation purification and molecular sieve adsorption on the obtained upper oil phase to produce high-purity tetramethylsilane.

[0006] However, although the first method can remove most of the compounds containing Si-Cl bonds, it will cause the loss of methylchlorosilane in the low-boiling organic silicon to a certain extent, increase the post-processing cost, and the process route is complicated. In the second method, the hydrogen chloride produced by the hydrolysis reaction will be partially dissolved in the oil phase, and the equipment in the distillation or adsorption stage needs to use corrosion-resistant materials or be lined with equipment, which increases the cost of equipment use to a certain extent. Summary of the invention

[0007] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0008] To this end, an embodiment of one aspect of the present invention provides a system for preparing tetramethylsilane, wherein the tetramethylsilane prepared by the system for preparing tetramethylsilane has high purity and low production cost.

[0009] Another aspect of the present invention provides a method for preparing tetramethylsilane.

[0010] According to an embodiment of the first aspect of the present invention, a system for preparing tetramethylsilane includes: a raw material tank for holding a mixture containing tetramethylsilane; a distillation device, the distillation device including a first distillation tower and a second distillation tower, the first distillation tower is connected to the raw material tank and the second distillation tower, the first distillation tower is used to remove chlorinated alkanes in the mixture to form a first mixture, and the second distillation tower is used to remove part of the small molecule alkanes in the first mixture to form a second mixture; an adsorption device, the adsorption device is connected to the second distillation tower, so as to remove the small molecule alkanes and olefins in the second mixture and form a third mixture; a sub-boiling distillation tower, the sub-boiling distillation tower is connected to the adsorption device, so as to purify the third mixture to obtain tetramethylsilane.

[0011] According to the tetramethylsilane preparation system of the embodiment of the present invention, the mixture is separated and purified by the first distillation tower and the second distillation tower to remove the chloroalkanes and small molecule alkanes in the mixture, and then the organic impurity compounds, metals and solid particulate impurities in the mixture are further removed by the adsorption device and the sub-boiling distillation tower, thereby obtaining pure tetramethylsilane. In addition, the tetramethylsilane preparation system of the present invention can preferentially remove the chloroalkanes to avoid the corrosion of the equipment by the acidic substances after the hydrolysis of the chloroalkanes, thereby reducing the production cost.

[0012] In some embodiments, the adsorption device includes a liquid phase adsorption column and a gas phase adsorption column, the liquid phase adsorption column is connected to the second distillation tower, and the gas phase adsorption column is connected to the liquid phase adsorption column and the sub-boiling distillation tower.

[0013] In some embodiments, the adsorption device further includes a superheater, which is connected to the liquid-phase adsorption column and the gas-phase adsorption column, and is used to heat the material entering the gas-phase adsorption column.

[0014] In some embodiments, the liquid phase adsorption column has a height-to-diameter ratio of 5-10, and / or the gas phase adsorption column has a height-to-diameter ratio of 5-10.

[0015] In some embodiments, a first molecular sieve is provided in the liquid phase adsorption column, and a second molecular sieve is provided in the gas phase adsorption column. The pore diameters of the first molecular sieve and the second molecular sieve are

[0016] In some embodiments, both the first distillation tower and the second distillation tower are packed towers, and the packing used in the first distillation tower and the second distillation tower is at least one of stainless steel θ ring packing, triangular spiral packing and glass spring packing.

[0017] In some embodiments, the raw material tank, the distillation device and the adsorption device are all made of internally polished stainless steel material, and the sub-boiling distillation tower is provided with a polyfluoro lining.

[0018] According to the method for preparing tetramethylsilane of the embodiment of the second aspect of the present invention, the system for preparing tetramethylsilane of the embodiment of the present invention is used, and the method for preparing tetramethylsilane comprises the following steps:

[0019] Passing the mixture containing tetramethylsilane into the first distillation tower to obtain a first mixture and high boiling products containing chloroalkanes, wherein the top pressure of the first distillation tower is 40 KPa-70 KPa, and the top temperature of the first distillation tower is 40-50° C.;

[0020] Passing the first mixture into the second distillation tower to obtain a second mixture and low-boiling products containing small molecular alkanes, the top pressure of the second distillation tower is 30KPa-50KPa, and the top temperature of the second distillation tower is 30-35°C;

[0021] Passing the second mixture into the adsorption device to obtain a third mixture and a mixture containing small molecule alkanes and olefins, wherein the pressure in the adsorption device is 20-50 kPa;

[0022] The third mixture is introduced into the sub-boiling distillation tower to obtain tetramethylsilane, the pressure of the sub-boiling distillation tower is 40KPa-60KPa, and the tower top temperature of the sub-boiling distillation tower is 30-40°C.

[0023] According to the method for preparing tetramethylsilane of the embodiment of the present invention, the mixture is first separated and purified by the first distillation tower and the second distillation tower to remove the chloroalkanes and small molecule alkanes in the mixture, and then the organic impurity compounds, metals and solid particulate impurities in the mixture are further removed by the adsorption device and the sub-boiling distillation tower, thereby obtaining pure tetramethylsilane. In addition, the method for preparing tetramethylsilane of the present invention can preferentially separate the chloroalkanes in the mixture, thereby avoiding the corrosion of the equipment by the acidic substances after the hydrolysis of the chloroalkanes, and reducing the production cost.

[0024] In some embodiments, passing the second mixture into an adsorption device comprises the following steps:

[0025] Passing the second mixture into the liquid phase adsorption column, wherein the adsorption temperature of the liquid phase adsorption column is 10-20°C;

[0026] The second mixture adsorbed by the liquid phase adsorption column is introduced into a gas phase adsorption column, and the adsorption temperature of the gas phase adsorption column is 40-50°C.

[0027] In some embodiments, the reflux feed ratio of the first distillation tower is 5-15, and the number of theoretical plates is 10-30;

[0028] The reflux feed ratio of the second distillation tower is 10-30, and the number of theoretical plates is 40-60.

[0029] In some embodiments, the first molecular sieve in the first distillation tower and the second molecular sieve in the second distillation tower are activated before use.

[0030] The activation treatment comprises: drying the first molecular sieve and the second molecular sieve under the protection of an inert gas, the treatment temperature being 300-380° C., and the treatment time being 2 hours.

[0031] In some embodiments, the high boiling substances and the low boiling substances are mixed and recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of a system for preparing tetramethylsilane according to an embodiment of the present invention.

[0033] Reference numerals:

[0034] 1. Raw material tank;

[0035] 2. distillation device; 21. first distillation tower; 22. second distillation tower;

[0036] 3. Adsorption device; 31. Liquid phase adsorption column; 32. Gas phase adsorption column; 33. Superheater;

[0037] 4. Sub-boiling distillation tower. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0039] A system for preparing tetramethylsilane and a method for preparing tetramethylsilane according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0040] like Figure 1 As shown, the system for preparing tetramethylsilane according to an embodiment of the present invention comprises a raw material tank 1, a distillation device 2, an adsorption device 3 and a sub-boiling distillation tower 4. The distillation device 2 comprises a first distillation tower 21 and a second distillation tower 22.

[0041] like Figure 1 As shown, one end of the first distillation tower 21 (such as Figure 1 The lower end of the first distillation tower 21 in the middle) is connected to the raw material tank 1, and the other end of the first distillation tower 21 (such as Figure 1 The upper end of the first distillation tower 21) and one end of the second distillation tower 22 (such as Figure 1 The first distillation tower 21 is connected to the upper end of the second distillation tower 22, the first distillation tower 21 is used to remove the chlorinated alkanes in the mixture to form a first mixture, and the second distillation tower 22 is used to remove part of the small molecular alkanes in the first mixture to form a second mixture.

[0042] like Figure 1 As shown, the adsorption device 3 is connected to the other end of the second distillation tower 22 (such as Figure 1 The lower end of the second distillation tower 22 is connected to the lower end of the second distillation tower 22 to remove small molecule alkanes and olefins in the second mixture and form a third mixture. The sub-boiling distillation tower 4 is connected to the adsorption device 3 to purify the third mixture to obtain pure tetramethylsilane.

[0043] According to the tetramethylsilane preparation system of the embodiment of the present invention, the mixture is separated and purified by the first distillation tower 21 and the second distillation tower 22 to remove the chloroalkanes and small molecule alkanes in the mixture, and then the organic impurity compounds, metals and solid particulate impurities in the mixture are further removed by the adsorption device 3 and the sub-boiling distillation tower 4, so as to obtain pure tetramethylsilane. In addition, the tetramethylsilane preparation system of the present invention can preferentially remove the chloroalkanes to avoid the corrosion of the equipment by the acidic substances after the hydrolysis of the chloroalkanes, thereby reducing the production cost.

[0044] Furthermore, if Figure 1 As shown, the adsorption device 3 includes a liquid phase adsorption column 31 and a gas phase adsorption column 32. One end of the liquid phase adsorption column 31 (such as Figure 1 The lower end of the liquid phase adsorption column 31) and the other end of the second distillation tower 22 (such as Figure 1 The lower end of the second distillation tower 22 is connected to the other end of the liquid adsorption column 31 (such as Figure 1 The upper end of the liquid phase adsorption column 31) and one end of the gas phase adsorption column 32 (such as Figure 1 The lower end of the gas phase adsorption column 32 is connected to the other end of the gas phase adsorption column 32 (such as Figure 1 The upper end of the gas phase adsorption column 32) and one end of the sub-boiling distillation tower 4 (such as Figure 1 Preferably, a superheater 33 is connected between the liquid phase adsorption column 31 and the gas phase adsorption column 32 to heat the material entering the gas phase adsorption column 32 from the liquid phase adsorption column 31.

[0045] It is understandable that if Figure 1As shown, the second mixture coming out of the second distillation tower 22 enters the liquid phase adsorption column 31, so that the small molecule alkanes and olefins in the second mixture can be further removed through the liquid phase adsorption column 31, and then the second mixture with some small molecule alkanes and olefins removed is heated and vaporized by the superheater 33, and then the vaporized second mixture is passed into the gas phase adsorption column 32, and then the small molecule alkanes and olefins in the second mixture are completely removed, and finally it is passed into the sub-boiling distillation tower 4 for deep separation and purification, so as to obtain high-purity tetramethylsilane.

[0046] Specifically, Figure 1 As shown, the height-to-diameter ratio of the liquid-phase adsorption column 31 is 5-10. It can be understood that the height-to-diameter ratio of the liquid-phase adsorption column 31 is: the ratio of the height of the liquid-phase adsorption column 31 to the diameter of the liquid-phase adsorption column 31. The adsorption temperature is controlled between 10-20°C. A first molecular sieve is provided in the liquid-phase adsorption column 31 to remove small molecule alkanes and olefins in the second mixture. The height-to-diameter ratio of the gas-phase adsorption column 32 is 5-10, the adsorption temperature is controlled between 40-50°C, and the pressure of the gas-phase adsorption column 32 is controlled between 20-50kPa. A second molecular sieve is provided in the gas-phase adsorption column 32 to further remove small molecule alkanes and olefins in the second mixture.

[0047] Alternatively, if Figure 1 As shown, the pore diameters of the first sub-sieve and the second molecular sieve are The first sub-sieve and the second molecular sieve can be molecular sieves of a single pore size or molecular sieves of multiple pore sizes. The first sub-sieve and the second molecular sieve need to be activated before use. The activation treatment is: under the protection of an inert gas, the first sub-sieve and the second molecular sieve are dried at 300 to 380°C for 2 hours. The inert gas can be nitrogen, argon or helium. Thus, the adsorption device 3 of the preparation system of tetramethylsilane according to the embodiment of the present invention can remove most of the small molecule alkanes and olefins in the second mixture.

[0048] In some embodiments, Figure 1 As shown, the first distillation tower 21 and the second distillation tower 22 are both packed towers, and the packing used in the first distillation tower 21 and the second distillation tower 22 is stainless steel θ ring packing, triangular spiral packing or glass spring packing. The raw material tank 1, the distillation device 2, the adsorption device 3 and the pipelines connected thereto are all made of internal polished stainless steel materials, and the sub-boiling distillation tower 4 is provided with a tetrafluoro lining, which can also be understood as the sub-boiling distillation tower 4 is a tetrafluoro lining metal tower, so that the preparation system of tetramethylsilane in the embodiment of the present invention has good corrosion resistance and reduces the investment cost of the equipment.

[0049] like Figure 1As shown, according to another aspect of the present invention, a method for preparing tetramethylsilane according to an embodiment of the present invention uses a system for preparing tetramethylsilane according to an embodiment of the present invention. The method for preparing tetramethylsilane comprises the following steps:

[0050] Passing the mixture containing tetramethylsilane into the first distillation tower 21 to obtain a first mixture and high boiling products containing chloroalkanes, the top pressure of the first distillation tower 21 is 40KPa-70KPa, and the top temperature of the first distillation tower 21 is 40-50°C;

[0051] The first mixture is passed into the second distillation tower 22 to obtain the second mixture and the low-boiling products containing small molecular alkanes, the top pressure of the second distillation tower 22 is 30KPa-50KPa, and the top temperature of the second distillation tower 22 is 30-35°C;

[0052] The second mixture is introduced into the liquid phase adsorption column 31, and the adsorption temperature of the liquid phase adsorption column 31 is 10-20°C;

[0053] The second mixture adsorbed by the liquid phase adsorption column 31 is passed into the gas phase adsorption column 32, and the adsorption temperature of the gas phase adsorption column 32 is 40-50°C to obtain a third mixture and a mixture containing small molecular alkanes and alkenes. The pressure in the adsorption device 3 is 20-50kpa;

[0054] The third mixture is introduced into a sub-boiling distillation tower 4 to obtain tetramethylsilane. The pressure of the sub-boiling distillation tower 4 is 40 KPa-60 KPa, and the tower top temperature of the sub-boiling distillation tower 4 is 30-40°C.

[0055] According to the method for preparing tetramethylsilane of the embodiment of the present invention, the mixture is first separated and purified by the first distillation tower 21 and the second distillation tower 22 to remove the chloroalkanes and small molecule alkanes in the mixture, and then the organic impurity compounds, metals and solid particulate impurities in the mixture are further removed by the adsorption device 3 and the sub-boiling distillation tower 4, so as to obtain pure tetramethylsilane. In addition, the method for preparing tetramethylsilane of the present invention can preferentially separate the chloroalkanes in the mixture, thereby avoiding the corrosion of the equipment by the acidic substances after the hydrolysis of the chloroalkanes, and reducing the production cost.

[0056] Further, the reflux feed ratio of the first distillation tower 21 is 5-15, and the number of theoretical plates is 10-30. The reflux feed ratio of the second distillation tower 22 is 10-30, and the number of theoretical plates is 40-60.

[0057] Furthermore, the first molecular sieve in the first distillation tower 21 and the second molecular sieve in the second distillation tower 22 are activated before use. The activation treatment includes: drying the first molecular sieve and the second molecular sieve under the protection of inert gas, the treatment temperature is 300-380°C, and the treatment time is 2h.

[0058] Optionally, the high boiling products generated by the first distillation tower 21 and the low boiling products generated by the second distillation tower 22 are recycled. The top of the first distillation tower 21 and the top of the second distillation tower 22 can be cooled by 7°C water, and the bottom of the first distillation tower 21 and the bottom of the second distillation tower 22 can be heated by hot water or heat transfer oil.

[0059] Preferably, the tower pressure of the sub-boiling distillation tower 4 is 50 kPa, and the tower top temperature of the sub-boiling distillation tower 4 is 34° C., so that high-purity electronic grade tetramethylsilane can be obtained.

[0060] The following describes a system for preparing tetramethylsilane and a method for preparing tetramethylsilane according to some specific examples of the present invention with reference to the accompanying drawings.

[0061] like Figure 1 As shown, the system for preparing tetramethylsilane according to an embodiment of the present invention includes a raw material tank 1, a distillation device 2, an adsorption device 3 and a sub-boiling distillation tower 4. The distillation device 2 includes a first distillation tower 21 and a second distillation tower 22, and the adsorption device 3 includes a liquid phase adsorption column 31, a gas phase adsorption column 32 and a superheater 33.

[0062] like Figure 1 As shown, the lower end of the first distillation tower 21 is connected to the raw material tank 1, and the upper end of the first distillation tower 21 is connected to the upper end of the second distillation tower 22. The first distillation tower 21 is used to remove the chlorinated alkanes in the mixture to form a first mixture, and the second distillation tower 22 is used to remove part of the small molecular alkanes in the first mixture to form a second mixture.

[0063] like Figure 1 As shown, the lower end of the liquid adsorption column 31 is connected to the lower end of the second distillation tower 22, the upper end of the liquid adsorption column 31 is connected to the lower end of the gas adsorption column 32, and the upper end of the gas adsorption column 32 is connected to the lower end of the sub-boiling distillation tower 4. The superheater 33 is arranged between the liquid adsorption column 31 and the gas adsorption column 32, and the superheater 33 is used to heat the material entering the gas adsorption column 32 from the liquid adsorption column 31.

[0064] It can be understood that the second mixture coming out of the second distillation tower 22 enters the liquid phase adsorption column 31, so that the small molecule alkanes and olefins in the second mixture can be further removed through the liquid phase adsorption column 31, and then the second mixture with some small molecule alkanes and olefins removed is heated and vaporized by the superheater 33, and then the vaporized second mixture is passed into the gas phase adsorption column 32, and then the small molecule alkanes and olefins in the second mixture are completely removed, and finally it is passed into the sub-boiling distillation tower 4 for deep separation and purification, so as to obtain high-purity tetramethylsilane.

[0065] like Figure 1As shown, the first distillation tower 21 and the second distillation tower 22 are both packed towers, and the packings used in the first distillation tower 21 and the second distillation tower 22 are stainless steel θ ring packings, triangular spiral packings or glass spring packings.

[0066] like Figure 1 As shown, the height-to-diameter ratio of the liquid phase adsorption column 31 is 5, and the adsorption temperature is controlled to 15°C. A first molecular sieve is provided in the liquid phase adsorption column 31 to remove small molecular alkanes and olefins in the second mixture. The height-to-diameter ratio of the gas phase adsorption column 32 is 5, the adsorption temperature is controlled to 45°C, and the pressure of the gas phase adsorption column 32 is controlled to 35kpa. A second molecular sieve is provided in the gas phase adsorption column 32 to further remove small molecular alkanes and olefins in the second mixture.

[0067] like Figure 1 As shown, the pore diameters of the first sub-sieve and the second molecular sieve are Before use, the first sub-sieve and the second molecular sieve need to be dried at 300-380°C for 2 hours under the protection of inert gas, wherein the inert gas can be nitrogen, argon or helium. Thus, the adsorption device 3 of the tetramethylsilane preparation system according to the embodiment of the present invention can remove most of the small molecular alkanes and alkenes in the second mixture.

[0068] like Figure 1 As shown, a method for preparing tetramethylsilane according to an embodiment of another aspect of the present invention comprises the following steps:

[0069] The mixture containing tetramethylsilane is introduced into the first distillation tower 21 to obtain a first mixture and a high boiling product containing chloroalkane, the top pressure of the first distillation tower 21 is 50 Kpa, the top temperature of the first distillation tower 21 is 46° C., the reflux feed ratio of the first distillation tower 21 is 5-15, and the theoretical plate number is 10-30;

[0070] The first mixture is introduced into the second distillation tower 22 to obtain the second mixture and the low-boiling products containing small molecular alkanes, the top pressure of the second distillation tower 22 is 40Kpa, the top temperature of the second distillation tower 22 is 32°C, the reflux feed ratio of the second distillation tower 22 is 10-30, and the theoretical plate number is 40-60;

[0071] The second mixture is introduced into the liquid phase adsorption column 31, and the adsorption temperature of the liquid phase adsorption column 31 is 15°C;

[0072] The second mixture adsorbed by the liquid phase adsorption column 31 is passed into the gas phase adsorption column 32. The adsorption temperature of the gas phase adsorption column 32 is 45° C. to obtain a third mixture and a mixture containing small molecular alkanes and olefins. The pressure of the gas phase adsorption column 32 is controlled to be 35 kPa.

[0073] The third mixture is introduced into the sub-boiling distillation tower 4, the pressure of the sub-boiling distillation tower 4 is 50Kpa, and the tower top temperature of the sub-boiling distillation tower 4 is 34° C. Thus, high-purity electronic grade tetramethylsilane can be obtained, and the tetramethylsilane obtained by the preparation method of tetramethylsilane in the embodiment of the present invention has a purity of 99.99% after GC-MS detection.

[0074] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0075] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0076] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0078] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0079] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing tetramethylsilane using a tetramethylsilane preparation system, characterized in that: The preparation system comprises: A raw material tank, used for holding a mixture containing tetramethylsilane; A distillation device, the distillation device comprising a first distillation tower and a second distillation tower, the first distillation tower is connected to the raw material tank and the second distillation tower, the first distillation tower is used to remove chlorinated alkanes in the mixture to form a first mixture, and the second distillation tower is used to remove part of small molecular alkanes in the first mixture to form a second mixture; an adsorption device, the adsorption device being connected to the second distillation tower to remove small molecule alkanes and olefins in the second mixture and form a third mixture, the adsorption device comprising a liquid phase adsorption column and a gas phase adsorption column, the liquid phase adsorption column being connected to the second distillation tower, and the gas phase adsorption column being connected to the liquid phase adsorption column; a sub-boiling distillation tower, the sub-boiling distillation tower being in communication with the adsorption device, for purifying the third mixture to obtain tetramethylsilane, the gas phase adsorption column being in communication with the sub-boiling distillation tower; The preparation method comprises the following steps: Passing the mixture containing tetramethylsilane into the first distillation tower to obtain a first mixture and high boiling products containing chloroalkanes, wherein the top pressure of the first distillation tower is 40 KPa-70 KPa, and the top temperature of the first distillation tower is 40-50° C.; Passing the first mixture into the second distillation tower to obtain a second mixture and low-boiling products containing small molecular alkanes, the top pressure of the second distillation tower is 30KPa-50KPa, and the top temperature of the second distillation tower is 30-35°C; Passing the second mixture into the adsorption device to obtain a third mixture and a mixture containing small molecule alkanes and olefins, wherein the pressure in the adsorption device is 20-50 kPa; Passing the third mixture into the sub-boiling distillation tower to obtain tetramethylsilane, the pressure of the sub-boiling distillation tower is 40KPa-60KPa, and the tower top temperature of the sub-boiling distillation tower is 30-40°C; Passing the second mixture into an adsorption device comprises the following steps: Passing the second mixture into the liquid phase adsorption column, wherein the adsorption temperature of the liquid phase adsorption column is 10-20°C; The second mixture adsorbed by the liquid phase adsorption column is introduced into a gas phase adsorption column, and the adsorption temperature of the gas phase adsorption column is 40-50°C.

2. The method according to claim 1, characterized in that: The adsorption device further comprises a superheater, which is communicated with the liquid-phase adsorption column and the gas-phase adsorption column, and is used to heat the material entering the gas-phase adsorption column.

3. The method according to claim 1, characterized in that The liquid phase adsorption column has a height-to-diameter ratio of 5-10, and / or the gas phase adsorption column has a height-to-diameter ratio of 5-10.

4. The method according to claim 1, characterized in that: The liquid phase adsorption column is provided with a first molecular sieve, and the gas phase adsorption column is provided with a second molecular sieve. The pore diameters of the first molecular sieve and the second molecular sieve are 5. The method according to claim 1, characterized in that The first distillation tower and the second distillation tower are both packed towers, and the packing used in the first distillation tower and the second distillation tower is at least one of stainless steel θ ring packing, triangular spiral packing and glass spring packing.

6. The method according to any one of claims 1 to 5, characterized in that: The raw material tank, the distillation device and the adsorption device are all made of internally polished stainless steel material, and the sub-boiling distillation tower is provided with a polyfluorite lining.

7. The method according to claim 1, characterized in that The reflux feed ratio of the first distillation tower is 5-15, and the number of theoretical plates is 10-30; The reflux feed ratio of the second distillation tower is 10-30, and the number of theoretical plates is 40-60.

8. The method according to claim 1, characterized in that The first molecular sieve in the first distillation tower and the second molecular sieve in the second distillation tower are activated before use. The activation treatment comprises: drying the first molecular sieve and the second molecular sieve under the protection of an inert gas, the treatment temperature being 300-380° C., and the treatment time being 2 hours.

9. The method according to claim 1, characterized in that: The following steps are also included: The high boiling substances and the low boiling substances are mixed and recycled.

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