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CN112028926A - Separation device and separation method for removing silicon tetrachloride in organic silicon monomer azeotrope - Google Patents

Separation device and separation method for removing silicon tetrachloride in organic silicon monomer azeotrope Download PDF

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CN112028926A
CN112028926A CN201910477294.XA CN201910477294A CN112028926A CN 112028926 A CN112028926 A CN 112028926A CN 201910477294 A CN201910477294 A CN 201910477294A CN 112028926 A CN112028926 A CN 112028926A
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tower
separation
bed reactor
fixed bed
separation tower
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CN112028926B (en
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蒋鹏
银波
陈国辉
王三跃
后文杰
王聪
江庆云
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Xinte Energy Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02Silicon compounds
    • C07F7/08Compounds having one or more C—Si linkages
    • C07F7/20Purification, separation
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • C01B33/08Compounds containing halogen
    • C01B33/107Halogenated silanes
    • C01B33/1071Tetrachloride, trichlorosilane or silicochloroform, dichlorosilane, monochlorosilane or mixtures thereof
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02Silicon compounds
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    • C07F7/12Organo silicon halides

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Abstract

The invention discloses a separation device and a separation method for removing silicon tetrachloride in an organosilicon monomer azeotrope, wherein the separation device comprises: the first separation tower is used for separating the organic silicon monomer azeotrope; the fixed bed reactor is connected with the top of the first separation tower, and the material at the top of the first separation tower flows into the fixed bed reactor to react with the dichlorosilane product under the catalysis of the catalyst to generate trichlorosilane; and the second separation tower is connected with the fixed bed reactor, is used for separating the material flowing out of the fixed bed reactor, obtains a trimethylchlorosilane product at the tower kettle of the second separation tower, and obtains a dichlorosilane product at the tower top of the second separation tower. The method can greatly reduce the load of the rectifying device in the prior art, remove the silicon tetrachloride azeotrope in the organosilicon monomer azeotrope and convert the silicon tetrachloride into the trichlorosilane.

Description

Separation device and separation method for removing silicon tetrachloride in organic silicon monomer azeotrope
Technical Field
The invention belongs to the technical field of separation of organochlorosilane monomers, and particularly relates to a separation device and a separation method for removing silicon tetrachloride in an organosilicon monomer azeotrope.
Background
An organosilicon compound generally refers to a compound containing Si-C bonds, and a polymer of the organosilicon compound has a plurality of excellent properties due to the properties of inorganic materials and organic materials, so that the organosilicon compound is widely applied to various industries such as electronics, electricity, construction, chemical industry, textile, light industry, medical treatment and the like, and is called industrial monosodium glutamate. The organosilicon monomer is used as the initial production raw material of organosilicon high polymer and occupies an important position in the organosilicon industry. The methyl chlorosilane mainly refers to four types of methyl hydrogen-containing dichlorosilane, methyl trichlorosilane, dimethyl dichlorosilane and trimethyl monochlorosilane, is used as an important organosilicon monomer type, and the purity of a separated product plays an important role in the processing of subsequent products.
Regardless of the method used to produce organochlorosilanes, multicomponent mixtures are obtained, the products being particularly complex in the direct process. Especially, when methyl chlorosilane is synthesized, the components are more, the boiling point difference is small, and the separation and purification are quite difficult. However, the preparation of polysiloxane products requires the use of monomers with different functional groups with higher purity as raw materials, so that the separation and purification of methylchlorosilanes plays an important role in the organosilicon industry and the investment ratio thereof.
At present, the industrial synthesis method adopts a direct method to obtain methyl chlorosilane monomer crude products, and according to data reports, the crude products contain 41 components, and low-boiling-point substances and methyl chloride are removed through preliminary separation, and then the crude products enter a separation process. In practice, it is not necessary to separate each product component one by one in the downstream industry, and the main purpose of separating the mixed methylchlorosilanes is to extract as much as possible of products such as dimethyldichlorosilane, trimethylmonochlorosilane, monomethyltrichlorosilane, dimethylchlorosilane containing hydrogen, silicon tetrachloride and high boilers with sufficiently high purity, and the requirements for the purity of methylchlorosilanes with various functionalities depend mainly on the actual requirements for the production of polysiloxanes. In the industry of producing methyl chlorosilane monomers by a direct method, due to the restriction of factors such as a catalyst, process conditions and the like, in a monomer crude product, besides a target product methyl chlorosilane, by-products of silicon tetrachloride and trimethyl chlorosilane have boiling points which are relatively close (the boiling point of trimethyl chlorosilane is 57.9 ℃, 101KPa, the boiling point of silicon tetrachloride is 57.6 ℃, 101KPa), and an azeotrope is easily formed. The difficulty in separating and purifying methyl chlorosilane is mainly caused by the azeotropic problem between trimethyl monochlorosilane, methyl hydrosilane and silicon tetrachloride (the boiling point of trimethyl monochlorosilane is 57.9 ℃, 101 KPa; the boiling point of silicon tetrachloride is 57.6 ℃, 101KPa) except that the difference of the boiling points among the components is small, so that the purity of the separated product cannot meet the expected requirement, and meanwhile, in the hydrolysis process, the silicon tetrachloride reacts with water to produce solid substances of silicon dioxide, which can cause adverse factors such as equipment and pipeline blockage for a long time.
Disclosure of Invention
The invention aims to solve the technical problem of providing a separation device and a separation method for removing silicon tetrachloride in an organosilicon monomer azeotrope, aiming at overcoming the defects in the prior art, so that the load of a rectification device in the prior art can be greatly reduced, the silicon tetrachloride azeotrope in the organosilicon monomer azeotrope is removed, and the silicon tetrachloride is converted into trichlorosilane.
The technical scheme adopted for solving the technical problem of the invention is to provide a separation device for removing silicon tetrachloride in an organosilicon monomer azeotrope, wherein a methyl chlorosilane monomer is synthesized by a direct method to obtain a methyl chlorosilane monomer crude product, the methyl chlorosilane monomer crude product is subjected to primary rectification to remove high-boiling residues and low-boiling residues to obtain an organosilicon monomer azeotrope, and the organosilicon monomer azeotrope comprises the following components in parts by weight: trimethylchlorosilane, silicon tetrachloride, the separator includes:
the first separation tower is used for separating the organic silicon monomer azeotrope, obtaining a dimethyldichlorosilane product at the tower bottom of the first separation tower, obtaining a tower top material of the first separation tower at the tower top of the first separation tower, wherein the tower top material of the first separation tower comprises silicon tetrachloride;
the fixed bed reactor is connected with the top of the first separation tower, dichlorosilane is also fed into an inlet of the fixed bed reactor, a catalyst for catalyzing the dichlorosilane and silicon tetrachloride to perform a reverse disproportionation reaction to generate trichlorosilane is filled in the fixed bed reactor, and materials at the top of the first separation tower flow into the fixed bed reactor and are fed into a product containing dichlorosilane in the fixed bed reactor to perform a reverse disproportionation reaction to generate trichlorosilane under the catalytic action of the catalyst;
and the second separation tower is connected with the fixed bed reactor, is used for separating the material flowing out of the fixed bed reactor, obtains a trimethylchlorosilane product at the tower kettle of the second separation tower, and obtains a dichlorosilane product at the tower top of the second separation tower.
Preferably, the separation device for removing silicon tetrachloride in the organosilicon monomer azeotrope further comprises:
and the feeding mixer is arranged between the first separation tower and the fixed bed reactor, the inlet of the feeding mixer is connected with the tower top of the first separation tower, the outlet of the feeding mixer is connected with the fixed bed reactor, the inlet of the feeding mixer is also used for introducing a product containing dichlorosilane, and the feeding mixer is used for mixing the tower top material of the first separation tower with the product containing dichlorosilane.
Preferably, the top of the second separation tower is connected with the inlet of the fixed bed reactor, and dichlorosilane products separated from the top of the second separation tower flow into the fixed bed reactor.
Preferably, a side column plate is arranged on the second separation tower and used for side-drawing trichlorosilane products with the purity of more than 99mas percent.
The invention also provides a separation method using the separation device for removing the silicon tetrachloride in the organosilicon monomer azeotrope, which comprises the following steps:
separating the organic silicon monomer azeotrope by a first separation tower, obtaining a dimethyldichlorosilane product at a tower kettle of the first separation tower, obtaining a tower top material of the first separation tower at the tower top of the first separation tower, wherein the tower top material of the first separation tower comprises silicon tetrachloride;
introducing the material at the top of the first separation tower into a fixed bed reactor, introducing a product containing dichlorosilane into the fixed bed reactor, and carrying out a reverse disproportionation reaction under the catalytic action of a catalyst to generate trichlorosilane;
and (3) separating the material flowing out of the fixed bed reactor through a second separation tower, obtaining a trimethylchlorosilane product at the tower bottom of the second separation tower, and obtaining a dichlorosilane product at the tower top of the second separation tower.
Preferably, the pressure in the first separation tower is 200-300 Kpa, and the temperature is the saturation temperature of the organosilicon monomer azeotrope. The number of the plates of the first separation column is 100-110.
Preferably, the pressure in the fixed bed reactor is 200-350 Kpa, and the temperature is 80-100 ℃.
Preferably, the pressure in the second separation tower is 350-450 Kpa, and the temperature is 55-60 ℃.
Preferably, the molar ratio of the dichlorosilane-containing product introduced into the fixed bed reactor to the silicon tetrachloride in the overhead material of the first separation tower is (1.1-1.25): 1.
preferably, the separation method further comprises the steps of: and introducing the dichlorosilane product separated from the tower top of the second separation tower into the fixed bed reactor.
Preferably, the separation method further comprises the steps of: and (3) extracting a trichlorosilane product through a lateral line tower plate on the second separation tower, wherein the number of the tower plates of the lateral line tower plate is 45-50.
Preferably, the catalyst is a basic quaternary ammonium based macroporous cross-linked resin dry-based catalyst and/or an anionic resin. The diameter of the catalyst is 0.5-1.5 mm, the bulk density is 0.30-0.50 g/ml, and the wear resistance is more than 95%.
In conclusion, the separation device and the method for removing silicon tetrachloride in the organosilicon monomer azeotrope in the invention use dichlorosilane to remove azeotropic silicon tetrachloride in the organosilicon monomer, provide a new process route and device, can greatly reduce the load of a rectifying device in the prior art, remove the silicon tetrachloride azeotrope in the organosilicon monomer azeotrope, convert the silicon tetrachloride into trichlorosilane, have large boiling point difference between the trichlorosilane and the trimethylchlorosilane, can separate the trichlorosilane and the trimethylchlorosilane by a simple rectifying mode, improve the purity of the separated trimethylchlorosilane product to more than 98 percent, effectively reduce the consumption of cooling water and steam of a rectifying tower in the prior art, reduce the load and energy consumption, improve the purity of the trimethylchlorosilane, and simultaneously avoid the difficult problem of pipeline and equipment blockage caused by solid silicon dioxide generated in the hydrolysis process of the monomeric silicon tetrachloride in the subsequent process, the parking maintenance cost and the risk of the production process caused by equipment blockage are reduced.
Drawings
FIG. 1 is a schematic structural diagram of a separation device for removing silicon tetrachloride from an organosilicon monomer azeotrope in example 2 of the present invention.
In the figure: 1-a first separation column; 2-fixed bed reactor; 3-a second separation column; 4-a feed mixer; 5-a first condenser; 6-a second condenser; 7-a third condenser; 8-a fourth condenser; 9-sidetrack trays.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Reference will now be made in detail to embodiments of the present patent, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present patent and are not to be construed as limiting the present patent.
Example 1
This embodiment provides a separator of silicon tetrachloride among desorption organosilicon monomer azeotrope, and methyl chlorosilane monomer is synthesized to the direct method and is obtained methyl chlorosilane monomer crude product, and methyl chlorosilane monomer crude product gets organic silicon monomer azeotrope through elementary rectification, gets rid of high boiling thing, low boiling thing, and organic silicon monomer azeotrope includes: trimethylchlorosilane, silicon tetrachloride, the separator includes:
the first separation tower is used for separating the organic silicon monomer azeotrope, obtaining a dimethyldichlorosilane product at the tower bottom of the first separation tower, obtaining a tower top material of the first separation tower at the tower top of the first separation tower, wherein the tower top material of the first separation tower comprises silicon tetrachloride;
the fixed bed reactor is connected with the top of the first separation tower, dichlorosilane is also fed into an inlet of the fixed bed reactor, a catalyst for catalyzing the dichlorosilane and silicon tetrachloride to perform a reverse disproportionation reaction to generate trichlorosilane is filled in the fixed bed reactor, and materials at the top of the first separation tower flow into the fixed bed reactor and are fed into a product containing dichlorosilane in the fixed bed reactor to perform a reverse disproportionation reaction to generate trichlorosilane under the catalytic action of the catalyst;
and the second separation tower is connected with the fixed bed reactor, is used for separating the material flowing out of the fixed bed reactor, obtains a trimethylchlorosilane product at the tower kettle of the second separation tower, and obtains a dichlorosilane product at the tower top of the second separation tower.
The embodiment also provides a separation method using the separation device for removing silicon tetrachloride in the organosilicon monomer azeotrope, which comprises the following steps:
separating the organic silicon monomer azeotrope by a first separation tower, obtaining a dimethyldichlorosilane product at a tower kettle of the first separation tower, obtaining a tower top material of the first separation tower at the tower top of the first separation tower, wherein the tower top material of the first separation tower comprises silicon tetrachloride;
introducing the material at the top of the first separation tower into a fixed bed reactor, introducing a product containing dichlorosilane into the fixed bed reactor, and carrying out a reverse disproportionation reaction under the catalytic action of a catalyst to generate trichlorosilane;
and (3) separating the material flowing out of the fixed bed reactor through a second separation tower, obtaining a trimethylchlorosilane product at the tower bottom of the second separation tower, and obtaining a dichlorosilane product at the tower top of the second separation tower.
The separation device and the method for removing silicon tetrachloride in the organosilicon monomer azeotrope in the embodiment use dichlorosilane to remove azeotropic silicon tetrachloride in the organosilicon monomer, provide a new process route and device, can greatly reduce the load of a rectification device in the prior art, remove the silicon tetrachloride azeotrope with the content of 20-30 mas percent in the organosilicon monomer azeotrope, convert the silicon tetrachloride into trichlorosilane, have large boiling point difference between the trichlorosilane and trimethylchlorosilane, can separate the trichlorosilane and the trimethylchlorosilane in a simple rectification mode, improve the purity of the separated trimethylchlorosilane product to more than 98 percent, effectively reduce the consumption of cooling water and steam of a rectification tower in the prior art, reduce the load and energy consumption, improve the purity of the trimethylchlorosilane, and simultaneously avoid the problem of pipeline and equipment blockage caused by solid silicon dioxide generated in the hydrolysis process of the monomeric silicon tetrachloride in the subsequent process, the parking maintenance cost and the risk of the production process caused by equipment blockage are reduced.
Example 2
As shown in fig. 1, this embodiment provides a separation device for removing silicon tetrachloride in an organosilicon monomer azeotrope, a methylchlorosilane monomer is synthesized by a direct method to obtain a crude methylchlorosilane monomer product, the crude methylchlorosilane monomer product is subjected to primary rectification separation to remove high-boiling residues and low-boiling residues to obtain an organosilicon monomer azeotrope, and the organosilicon monomer azeotrope mainly includes: trimethyl chlorosilane, silicon tetrachloride, separator includes:
the first separation tower 1 is used for separating the organic silicon monomer azeotrope, obtaining a dimethyldichlorosilane product with the content of more than 99 mas% at the tower bottom of the first separation tower 1, obtaining a tower top material of the first separation tower 1 at the tower top of the first separation tower 1, wherein the tower top material of the first separation tower 1 comprises silicon tetrachloride;
the fixed bed reactor 2 is connected with the top of the first separation tower 1, dichlorosilane is also fed into an inlet of the fixed bed reactor 2, a catalyst for catalyzing the dichlorosilane and silicon tetrachloride to perform a reverse disproportionation reaction to generate trichlorosilane is filled in the fixed bed reactor 2, and materials at the top of the first separation tower 1 flow into the fixed bed reactor 2 and are fed into a dichlorosilane-containing product in the fixed bed reactor 2 to perform a reverse disproportionation reaction to generate trichlorosilane under the catalysis of the catalyst; specifically, the fixed bed reactor 2 in this embodiment has a volume of 8 cubic meters per bed, a diameter of 1.5 meters, and a height of 6 meters, and is internally filled with basic quaternary ammonium-based macroporous crosslinked resin (supplied by Tianjin university, a catalyst used in this embodiment, and produced by many domestic enterprises).
And the second separation tower 3 is connected with the fixed bed reactor 2, the second separation tower 3 is used for separating the materials flowing out of the fixed bed reactor 2, trimethylchlorosilane products with the purity higher than 98 mas% are obtained at the tower bottom of the second separation tower 3, and dichlorosilane products with the purity not lower than 99 mas% are obtained at the tower top of the second separation tower 3.
Specifically, the fixed bed reactor 2 in the present embodiment is further provided with a temperature detector for monitoring temperature, and a pressure detector for monitoring pressure. The solid bed reactor has two sets, wherein one set is used, and the other set is standby, so that the maintenance and the switching are convenient.
It should be noted that, the separation apparatus for removing silicon tetrachloride in an organosilicon monomer azeotrope in this embodiment further includes:
and the feeding mixer 4 is arranged between the first separation tower 1 and the fixed bed reactor 2, the inlet of the feeding mixer 4 is connected with the top of the first separation tower 1, the outlet of the feeding mixer 4 is connected with the fixed bed reactor 2, the inlet of the feeding mixer 4 is also used for introducing a product containing dichlorosilane, and the feeding mixer 4 is used for mixing the material on the top of the first separation tower 1 with the product containing dichlorosilane. Specifically, an outsourced byproduct dichlorosilane product in the polycrystalline silicon production process is stored in a tank area, is conveyed to a feeding mixer 4 through a pump to be fully mixed with the materials on the top of the first separation tower 1, and is fed into the fixed bed reactor 2 through an inlet at the bottom of the fixed bed reactor 2. If the enterprises have the production capacity of polysilicon and organic silicon, the polysilicon byproduct dichlorosilane can be directly utilized.
It should be noted that, the separation apparatus for removing silicon tetrachloride in an organosilicon monomer azeotrope in this embodiment further includes:
the first condenser 5 is connected with the top of the first separation tower 1, after materials at the top of the first separation tower 1 are condensed by the first condenser 5, one part of the materials is used as reflux liquid of the first separation tower 1 to maintain the balance of the tower, and the other part of the materials is introduced into the feeding mixer 4 to be mixed;
the second condenser 6 is connected with the tower kettle of the first separation tower 1, and the second condenser 6 is used for condensing tower kettle liquid of the first separation tower 1;
the third condenser 7 is connected with the top of the second separation tower 3, after materials at the top of the second separation tower 3 are condensed by the third condenser 7, one part of the materials is used as reflux liquid of the second separation tower 3 to maintain the balance of the tower, and the other part of the materials is introduced into the feed mixer 4 to be mixed;
and the fourth condenser 8 is connected with the tower kettle of the second separation tower 3, and the fourth condenser 8 is used for condensing the tower kettle liquid of the second separation tower 3.
In the embodiment, the top of the second separation tower 3 is connected to the inlet of the fixed bed reactor 2, and the dichlorosilane product separated from the top of the second separation tower 3 flows into the fixed bed reactor 2.
It should be noted that in this embodiment, the second separation tower 3 is provided with a side-draw tray 9, and the side-draw tray 9 is used for side-drawing the trichlorosilane product with a purity of greater than 99 mas%.
The embodiment also provides a separation method using the separation device for removing silicon tetrachloride in the organosilicon monomer azeotrope, which comprises the following steps:
(1) the organosilicon monomer azeotrope is separated by a first separation column 1. The organic silicon monomer azeotrope mainly comprises trimethyl chlorosilane and silicon tetrachloride and also comprises a small amount of dimethyl dichlorosilane, wherein the proportion of the trimethyl chlorosilane is 60-75 mas, the proportion of the silicon tetrachloride is 20-30 mas, the pressure in the first separation tower 1 is 300Kpa, and the temperature is the saturation temperature of the organic silicon monomer azeotrope. The overhead temperature of the first separation column 1 is the corresponding mixture saturation temperature. The number of trays of the first separation column 1 was 105. Obtaining a dimethyldichlorosilane product with the content of more than 99 mas% at the tower bottom of the first separation tower 1, obtaining a tower top material of the first separation tower 1 at the tower top of the first separation tower 1, wherein the tower top material of the first separation tower 1 comprises silicon tetrachloride, and the content of trichlorosilane is 60-75 mas%.
(2) The material at the top of the first separation tower 1 is introduced into a feeding mixer 4, and the byproduct dichlorosilane product produced in the purchased polysilicon production process is stored in a tank area and is conveyed to the feeding mixer 4 through a pump to be fully mixed with the material at the top of the first separation tower 1. And the dichlorosilane product separated from the tower top of the second separation tower 3 is introduced into a feed mixer 4. The temperature in the feed mixer 4 was 50 ℃ and the pressure 5 bar. And then the mixed materials in the feeding mixer 4 are introduced into the fixed bed reactor 2. In this embodiment, the molar ratio of the dichlorosilane-containing product introduced into the fixed bed reactor 2 to the silicon tetrachloride in the overhead material of the first separation column 1 is 1.1: 1, carrying out a reverse disproportionation reaction under the catalytic action of a catalyst to generate trichlorosilane; in this example, the pressure in the fixed bed reactor 2 was 350Kpa and the temperature was 80 ℃ and the feed was liquid. The reaction conversion rate of the silicon tetrachloride and the dichlorosilane is over 97 percent. Preferably, the catalyst is a basic quaternary ammonium based macroporous cross-linked resin (free amine type anion exchange resin) dry-based catalyst and/or an anionic resin. Specifically, the catalyst in this example is a basic quaternary ammonium macroporous crosslinked resin (free amine anion exchange resin) dry-based catalyst. The diameter of the catalyst is 0.5-1.5 mm, the bulk density is 0.30-0.50 g/ml, and the wear resistance is more than 95%. After being converted by the fixed bed reactor 2, the materials flowing out of the fixed bed reactor 2 include: trichlorosilane, dichlorosilane and trimethylchlorosilane, wherein the proportion of the trichlorosilane is 20-30 mas percent, the proportion of the dichlorosilane is 10-15 mas percent, and the balance is the trimethylchlorosilane.
(3) The material exiting the fixed bed reactor 2 was separated by the second separation column 3, and in this example, the pressure in the second separation column 3 was 400Kpa and the temperature was 57 ℃. In the fixed bed reactor 2, silicon tetrachloride reacts with dichlorosilane to generate trichlorosilane, the boiling point of trichlorosilane under the standard atmospheric pressure is 31.8 ℃, the boiling point of dichlorosilane is 8.2 ℃, the boiling point difference between dichlorosilane and trimethylchlorosilane is about 25 ℃, and separation can be carried out through a simple second separation tower 3. Obtaining a trimethylchlorosilane product with the purity higher than 98mas percent at the tower bottom of the second separation tower 3, obtaining a dichlorosilane product with the purity not lower than 99mas percent at the tower top of the second separation tower 3, and continuously introducing the dichlorosilane product separated from the tower top of the second separation tower 3 into the fixed bed reactor 2 to continuously participate in the reaction. Trichlorosilane products with the purity of more than 99mas percent are extracted through a lateral line tray 9 on the second separation tower 3, and the number of the trays of the lateral line tray 9 is 50. The trichlorosilane product is used as a raw material for preparing the silane coupling agent, and can also be used for producing chloropropyltrichlorosilane, vinyl trichlorosilane and phenyl trichlorosilane products
The separation device and the method for removing silicon tetrachloride in the organosilicon monomer azeotrope in the embodiment use dichlorosilane to remove azeotropic silicon tetrachloride in the organosilicon monomer, provide a new process route and device, can greatly reduce the load of a rectification device in the prior art, remove the silicon tetrachloride azeotrope with the content of 20-30 mas percent in the organosilicon monomer azeotrope, convert the silicon tetrachloride into trichlorosilane, have large boiling point difference between the trichlorosilane and trimethylchlorosilane, can separate the trichlorosilane and the trimethylchlorosilane in a simple rectification mode, improve the purity of the separated trimethylchlorosilane product to more than 98 percent, effectively reduce the consumption of cooling water and steam of a rectification tower in the prior art, reduce the load and energy consumption, improve the purity of the trimethylchlorosilane, and simultaneously avoid the problem of pipeline and equipment blockage caused by solid silicon dioxide generated in the hydrolysis process of the monomeric silicon tetrachloride in the subsequent process, the parking maintenance cost and the risk of the production process caused by equipment blockage are reduced. The method in the embodiment can simultaneously solve the problem of difficult treatment of the byproduct dichlorosilane of the polycrystalline silicon in the production of the polycrystalline silicon and the organic silicon, and simultaneously solve the problem of difficult treatment of the azeotropic silicon tetrachloride in the production of the organic silicon. The device in the embodiment relates to a process flow without additionally arranging moving equipment, and has the advantages of low equipment failure rate, low investment and long service life.
Example 3
Boiling point of trimethylchlorosilane: 57.9 ℃, 101 KPa; the boiling point of the silicon tetrachloride is 57.6 ℃, and 101KPa is adopted; in the prior art, the mixture of the two substances cannot be effectively separated through general rectification. Sending the methyl chlorosilane monomer crude product synthesized by the direct method into a first-stage height removing tower to remove high-boiling-point multi-component compounds mainly comprising silicon-silicon bonds, silicon-oxygen-silicon bonds and the like; condensing the tower top product, sending the product to a secondary dephlegmation tower, rectifying the product to remove low-boiling-point multi-component compounds consisting of chloromethane, silicon tetrachloride, trimethylchlorosilane and monomethyl hydrogen-containing dichlorosilane, and continuously sending the product to a subsequent light component tower for separation; the product obtained at the tower bottom is continuously sent to a three-stage separation tower, a high-purity dimethyldichlorosilane product (the mass fraction is more than 99.5%) is obtained at the tower bottom, and the light component obtained at the tower top is sent to downstream white carbon black for treatment; and continuously conveying the product obtained at the top of the secondary low-removing tower to a light component separation tower, obtaining a product mainly containing methyl trichlorosilane at the top of the tower, obtaining an organic silicon monomer azeotrope at the bottom of the tower, wherein the organic silicon monomer azeotrope mainly contains trimethyl monochlorosilane and silicon tetrachloride, and the content of the silicon tetrachloride component is 20-30% (mass fraction)).
This example also provides a separation method using the separation apparatus for removing silicon tetrachloride in an organosilicon monomer azeotrope in example 2, which is different from the method in example 2 in that:
in the step (1), the pressure in the first separation tower is 250Kpa, and the temperature is the saturation temperature of the organosilicon monomer azeotrope. The number of trays of the first separation column was 100.
In the step (2), the temperature in the feed mixer was 30 ℃ and the pressure was 7 bar.
The mol ratio of the dichlorosilane-containing product introduced into the fixed bed reactor to the silicon tetrachloride in the overhead material of the first separation tower is 1.15: 1. the catalyst is an anionic resin.
The pressure in the fixed bed reactor was 200Kpa and the temperature was 90 ℃.
In the step (3), the pressure in the second separation column was 350Kpa and the temperature was 55 ℃. The number of the side column plates is 45.
Example 4
This example also provides a separation method using the separation apparatus for removing silicon tetrachloride in an organosilicon monomer azeotrope in example 2, which is different from the method in example 2 in that:
in the step (1), the pressure in the first separation tower is 200Kpa, and the temperature is the saturation temperature of the organosilicon monomer azeotrope. The number of trays of the first separation column was 110.
In the step (2), the temperature in the feed mixer was 60 ℃ and the pressure was 6 bar.
The mol ratio of the dichlorosilane-containing product introduced into the fixed bed reactor to the silicon tetrachloride in the overhead material of the first separation tower is 1.25: 1.
the pressure in the fixed bed reactor was 300Kpa and the temperature was 100 ℃.
In the step (3), the pressure in the second separation column was 450Kpa and the temperature was 60 ℃. The number of the side tray was 47 th.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims (11)

1. A separator for removing silicon tetrachloride in an organosilicon monomer azeotrope, which is characterized by comprising:
the first separation tower is used for separating the organic silicon monomer azeotrope, obtaining a dimethyldichlorosilane product at the tower bottom of the first separation tower, obtaining a tower top material of the first separation tower at the tower top of the first separation tower, wherein the tower top material of the first separation tower comprises silicon tetrachloride;
the fixed bed reactor is connected with the top of the first separation tower, dichlorosilane is also fed into an inlet of the fixed bed reactor, a catalyst for catalyzing the dichlorosilane and silicon tetrachloride to perform a reverse disproportionation reaction to generate trichlorosilane is filled in the fixed bed reactor, and materials at the top of the first separation tower flow into the fixed bed reactor and are fed into a product containing dichlorosilane in the fixed bed reactor to perform a reverse disproportionation reaction to generate trichlorosilane under the catalytic action of the catalyst;
and the second separation tower is connected with the fixed bed reactor, is used for separating the material flowing out of the fixed bed reactor, obtains a trimethylchlorosilane product at the tower kettle of the second separation tower, and obtains a dichlorosilane product at the tower top of the second separation tower.
2. The separation device for removing silicon tetrachloride in the organosilicon monomer azeotrope according to claim 1, further comprising:
and the feeding mixer is arranged between the first separation tower and the fixed bed reactor, the inlet of the feeding mixer is connected with the tower top of the first separation tower, the outlet of the feeding mixer is connected with the fixed bed reactor, the inlet of the feeding mixer is also used for introducing a product containing dichlorosilane, and the feeding mixer is used for mixing the tower top material of the first separation tower with the product containing dichlorosilane.
3. The separation device for removing silicon tetrachloride in organosilicon monomer azeotrope according to claim 1, wherein the top of the second separation tower is connected with the inlet of the fixed bed reactor, and dichlorosilane product separated from the top of the second separation tower flows into the fixed bed reactor.
4. The separation device for removing silicon tetrachloride in the organosilicon monomer azeotrope according to any one of claims 1 to 3, wherein a side column plate is arranged on the second separation tower, and the side column plate is used for side-stream extraction of trichlorosilane products.
5. A separation method using the separation device for removing silicon tetrachloride in the organosilicon monomer azeotrope according to any one of claims 1 to 4 is characterized by comprising the following steps:
separating the organic silicon monomer azeotrope by a first separation tower, obtaining a dimethyldichlorosilane product at a tower kettle of the first separation tower, obtaining a tower top material of the first separation tower at the tower top of the first separation tower, wherein the tower top material of the first separation tower comprises silicon tetrachloride;
introducing the material at the top of the first separation tower into a fixed bed reactor, introducing a product containing dichlorosilane into the fixed bed reactor, and carrying out a reverse disproportionation reaction under the catalytic action of a catalyst to generate trichlorosilane;
and (3) separating the material flowing out of the fixed bed reactor through a second separation tower, obtaining a trimethylchlorosilane product at the tower bottom of the second separation tower, and obtaining a dichlorosilane product at the tower top of the second separation tower.
6. The separation method according to claim 5, wherein the pressure in the first separation tower is 200-300 Kpa, and the temperature is the saturation temperature of the organosilicon monomer azeotrope.
7. The separation method according to claim 5, wherein the pressure in the fixed bed reactor is 200 to 350Kpa and the temperature is 80 to 100 ℃.
8. The separation process according to claim 5, wherein the pressure in the second separation column is 350 to 450Kpa and the temperature is 55 to 60 ℃.
9. The separation method according to claim 5, wherein the molar ratio of the dichlorodihydrosilicon-containing product fed into the fixed bed reactor to the silicon tetrachloride in the overhead material of the first separation tower is (1.1-1.25): 1.
10. the separation method according to claim 5, wherein the apparatus of claim 3 is used, and further comprising the steps of: and introducing the dichlorosilane product separated from the tower top of the second separation tower into the fixed bed reactor.
11. The separation method according to any one of claims 5 to 10, wherein the apparatus of claim 4 is used, and the separation method further comprises the following steps: and (3) extracting a trichlorosilane product through a lateral line tower plate on the second separation tower, wherein the number of the tower plates of the lateral line tower plate is 45-50.
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