CN116119672A - Silicon tetrachloride purification system and method - Google Patents

Abstract

The invention provides a silicon tetrachloride purification system and a silicon tetrachloride purification method. The purification system of the silicon tetrachloride comprises a catalytic reaction unit and a rectification purification unit, wherein the catalytic reaction unit comprises a gas phase reactor and is used for reacting gas-phase silicon tetrachloride to be purified with hydrogen chloride under the action of a catalyst to obtain a mixture of purified silicon tetrachloride and low-boiling-point substances, and rectifying and separating the mixture of the purified silicon tetrachloride and the low-boiling-point substances to obtain purified silicon tetrachloride. The purification system catalytic reaction unit of silicon tetrachloride provided by the application is used for catalytically converting methyl chlorosilane in silicon tetrachloride to be purified into silicon tetrachloride and low-boiling substances, and the silicon tetrachloride and the low-boiling substances are separated by rectification through the rectification purification unit, so that purified silicon tetrachloride and low-boiling substances are obtained.

Description

Silicon tetrachloride purification system and method

Technical Field

The invention relates to the field of silicon tetrachloride purification, in particular to a silicon tetrachloride purification system and method.

Background

The purified silicon tetrachloride is a main raw material of the optical fiber preform, and is also used as a raw material for epitaxial deposition in semiconductor manufacturing, and the carbon and hydrogen content is an important index for purifying the silicon tetrachloride, and mainly exists in the form of methylchlorosilane, so that the quality of a product is directly affected.

At present, the purification of silicon tetrachloride mainly comprises conventional rectification, namely, photocatalytic chlorination reaction, wherein the conventional rectification is carried out by arranging rectification towers in series, a physical method is adopted, and according to the difference of the boiling points of impurity components and silicon tetrachloride, the separation and purification are carried out by multistage rectification, and as the boiling points of trimethylchlorosilane, methyltrichlorosilane and silicon tetrachloride are close, an azeotrope is formed with silicon tetrachloride, the difficulty of separation by conventional rectification is high, the multistage rectification towers are required to be arranged for series purification, the process flow is long, the system investment is high, and the final separation effect of the impurity components is limited. For example: the patent 201110101343.3 adopts a continuous rectification method to prepare purified silicon tetrachloride for optical fibers, and industrial grade silicon tetrachloride firstly removes light components and then enters a heavy component removal tower to remove heavy components, and then continuously enters a vacuum rectification tower to further separate light components which are difficult to separate, and the purified silicon tetrachloride for optical fibers is extracted from side lines. The 200910068887.7 patent adopts a continuous azeotropic light removal rectification method to prepare optical fiber silicon tetrachloride, and three rectification towers are arranged in a system to carry out cyclic purification.

The photocatalytic chlorination reaction is carried out by taking chlorine as a reaction reagent under the catalysis of ultraviolet light, carrying out chlorination reaction with methyl chlorosilane, trichlorosilane and other carbon-hydrogen-containing impurities in silicon tetrachloride, carrying out chlorine substitution on hydrogen, realizing conversion of physical properties of the impurities, improving the boiling point, increasing the boiling point difference with the silicon tetrachloride, and separating by rectification to realize separation of the carbon-hydrogen-containing impurities. For example: patent 201610880095.X discloses a preparation method of ultrapure silicon tetrachloride, which adopts a photochemical gas phase reactor to lead chlorine to have chlorination reaction with carbon-hydrogen-containing impurities under the catalysis of ultraviolet light, then uses a stripping tower to separate and remove excessive chlorine, and finally uses a rectifying tower to purify to obtain the ultrapure silicon tetrachloride. The patent 201110451830.2 provides a preparation method of silicon tetrachloride for optical fibers, which takes high-boiling point silicon tetrachloride generated in the production process of polysilicon as a raw material, takes inert or inert gas as a protective atmosphere, and introduces chlorine under the condition of illumination, so that impurity trichlorosilane in the silicon tetrachloride performs photochemical reaction in a photochemical gas phase reactor, and intermediate products are further rectified and purified to obtain high-purity silicon tetrachloride.

The carbon and hydrogen impurities mainly exist in the form of methyl chlorosilane, and because the boiling points of the trimethyl chlorosilane, the methyl trichlorosilane and the silicon tetrachloride are close, an azeotrope can be formed, the separation difficulty is high by means of conventional rectification, and a plurality of rectifying towers are required to be arranged in series for separation and purification, so that the process flow is long, the system investment is high, and the operation cost is high. When the chlorination conversion method is adopted for conversion, the chlorine gas which is a highly toxic substance is required to be used, and the safety control and the tail gas treatment during the use of the chlorine gas are difficult problems. Meanwhile, the process needs to use a light source for catalysis, and the material, the structural form and the large-scale of the gas phase reactor and the intensity and the permeability of the light source are one of the difficulties, so that the large-scale industrialized application is limited.

In view of this, the present invention has been made.

Disclosure of Invention

The invention mainly aims to provide a purification system and method for silicon tetrachloride, which are used for solving the problems that impurities in the silicon tetrachloride to be purified in the prior art are mainly methyl chlorosilane, partial methyl chlorosilane has a boiling point close to that of the silicon tetrachloride, azeotrope separation difficulty is high, a plurality of rectifying towers are adopted for separation and purification, the process flow is long, the operation cost is high, and a chlorination conversion method is adopted, chlorine is needed to be used as a raw material, safety control and tail gas treatment are difficult, and large-scale industrial application cannot be carried out.

In order to achieve the above object, according to one aspect of the present invention, there is provided a purification system of silicon tetrachloride, comprising: the catalytic reaction unit comprises a gas phase reactor, a catalyst is filled in the gas phase reactor, and the gas phase reactor is used for mixing gas-phase silicon tetrachloride to be purified with hydrogen chloride to react under the action of the catalyst to obtain a mixture of purified silicon tetrachloride and low-boiling-point substances; the rectification purification unit comprises a rectification tower which is connected with the gas phase reactor and is used for rectifying and separating the mixture of the purified silicon tetrachloride and the low-boiling-point substances to obtain the purified silicon tetrachloride and the low-boiling-point substances.

Further, the purification system also comprises a raw material supply unit, wherein the raw material supply unit comprises a hydrogen chloride storage tank, a silicon tetrachloride storage tank to be purified and a vaporizer, the hydrogen chloride storage tank and the silicon tetrachloride storage tank to be purified are respectively connected with the vaporizer, and the vaporizer is connected with the gas phase reactor.

Further, the rectification and purification unit also comprises a low-boiling-point substance storage tank, and the low-boiling-point substance storage tank is connected with a gas phase outlet of the rectification tower and is used for storing low-boiling-point substances discharged by the rectification tower.

Further, a condenser is arranged on a pipeline between the low-boiling-point substance storage tank and the rectifying tower.

Further, the rectification purification unit further comprises a purified silicon tetrachloride storage tank, wherein the purified silicon tetrachloride storage tank is connected with a liquid phase outlet of the rectification tower and is used for storing purified silicon tetrachloride discharged by the rectification tower.

Further, the rectification purification unit further comprises a reboiler, the reboiler is arranged on a pipeline between the rectification tower and the purified silicon tetrachloride storage tank, and the reboiler is further connected with the rectification tower.

Further, the catalyst comprises a carrier and an active ingredient, and the mass content of the active ingredient in the catalyst is 1-30%; the carrier is molecular sieve or zeolite, and the active ingredient is at least one selected from aluminum trichloride, copper chloride, zinc chloride, aluminum, copper, palladium or platinum.

Further, the catalyst is columnar or spherical, and the particle size is 1-5 mm.

According to another aspect of the present invention, there is also provided a purification method of silicon tetrachloride, the purification method comprising: step S1, mixing silicon tetrachloride to be purified and hydrogen chloride to react under the action of a catalyst to obtain a mixture of the purified silicon tetrachloride and low-boiling-point substances; s2, rectifying and separating the mixture of the purified silicon tetrachloride and the low-boiling-point substances to obtain the purified silicon tetrachloride and the low-boiling-point substances; wherein the catalyst has the same meaning as in the first aspect described above.

Further, in the step S1, silicon tetrachloride to be purified and hydrogen chloride are mixed and vaporized, and then the reaction is carried out.

Further, the vaporization pressure is 50 to 1500kPa.

Further, the pressure of the reaction is 50 to 1200kPa.

Further, in step S2, the rectification separation is performed in a rectification column.

Further, the pressure of the rectifying tower is 50-500 kPa, the reflux ratio is 7-20:1, the top temperature is 70-130 ℃, and the theoretical plate number is 65-75.

Further, in the step S1, the molar ratio of the hydrogen chloride to the methyl in the silicon tetrachloride to be purified is 1-2000, preferably 500-1000.

Further, the step S2 further comprises the step of carrying out reboiling treatment on the purified silicon tetrachloride and returning to continue rectification separation.

By applying the technical scheme, the purifying system catalytic reaction unit of the silicon tetrachloride is used for catalytically converting methyl chlorosilane in the silicon tetrachloride to be purified into silicon tetrachloride and low-boiling substances, and the silicon tetrachloride and the low-boiling substances are separated by rectification through the rectification purification unit, so that the purified silicon tetrachloride and the low-boiling substances are obtained, the system is simple, the process flow is short, the purifying system is applicable to industrial production, meanwhile, the use of severe poison chlorine is avoided, and the purifying system is safer and more environment-friendly.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:

FIG. 1 shows a schematic flow diagram of a purification system for silicon tetrachloride provided according to example 1 of the present invention; and

wherein the above figures include the following reference numerals:

11. a silicon tetrachloride storage tank to be purified; 12. a hydrogen chloride storage tank; 13. a vaporizer; 21. a gas phase reactor; 31. a rectifying tower; 32. a condenser; 33. and (3) a reboiler.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.

As analyzed by the background technology of the application, impurities in the prior silicon tetrachloride to be purified mainly exist in the form of methyl chlorosilane, and as the boiling points of the trimethyl chlorosilane, the methyl trichlorosilane and the silicon tetrachloride are close, an azeotrope can be formed, and a plurality of rectifying towers are adopted for separation and purification, so that the process flow is long, the system investment is high, and the operation cost is high; the chlorine conversion method is adopted for conversion, and highly toxic chlorine is needed, so that the problems of difficult safety control and tail gas treatment during the use of the chlorine exist, and the large-scale industrial application is difficult. To solve this problem, the present application provides a purification system and method for silicon tetrachloride.

In an exemplary embodiment of the present application, as shown in fig. 1, the present application provides a purification system of silicon tetrachloride, as shown in fig. 1, the system comprises a catalytic reaction unit and a rectification purification unit, the catalytic reaction unit comprises a gas phase reactor 21, a catalyst is filled in the gas phase reactor 21, and the gas phase reactor 21 is used for mixing the silicon tetrachloride to be purified in gas phase with hydrogen chloride for reaction under the action of the catalyst to obtain a mixture of purified silicon tetrachloride and low-boiling substances; the rectification and purification unit comprises a rectification tower 31, and the rectification tower 31 is connected with the gas phase reactor 21 and is used for rectifying and separating the mixture of the purified silicon tetrachloride and the low-boiling-point substances to obtain the purified silicon tetrachloride and the low-boiling-point substances.

By applying the technical scheme, the purifying system catalytic reaction unit of the silicon tetrachloride is used for catalytically converting methyl chlorosilane in the silicon tetrachloride to be purified into silicon tetrachloride and low-boiling substances, and the silicon tetrachloride and the low-boiling substances are separated by rectification through the rectification purification unit, so that the purified silicon tetrachloride and the low-boiling substances are obtained, the system is simple, the process flow is short, the purifying system is applicable to industrial production, meanwhile, the use of severe poison chlorine is avoided, and the purifying system is safer and more environment-friendly.

In some embodiments of the present application, the purification system further comprises a raw material supply unit comprising a hydrogen chloride storage tank 12, a silicon tetrachloride to be purified storage tank 11 and a vaporizer 13, wherein the hydrogen chloride storage tank 12 and the silicon tetrachloride to be purified storage tank 11 are respectively connected with the vaporizer 13, and the vaporizer 13 is used for mixing and vaporizing hydrogen chloride and silicon tetrachloride to be purified into a mixed gas to be reacted. The vaporizer 13 is connected to the gas phase reactor 21 for delivering the gas mixture to be reacted into the gas phase reactor 21 for reaction under the action of a catalyst.

In order to store methane conveniently, the preferred rectification and purification unit further comprises a low-boiling-point substance storage tank, wherein the low-boiling-point substance storage tank is arranged at the top of the rectification column 31, is connected with a gas phase outlet of the rectification column 31 and is used for storing low-boiling-point substances discharged by the rectification column 31, and the low-boiling-point substances comprise methane, unreacted hydrogen chloride and the like.

In order to facilitate the storage of methane, a condenser 32 is preferably further disposed on a pipeline between the low-boiling-point substance storage tank and the rectifying tower 31, and the condenser 32 is used for condensing the low-boiling-point substance and then delivering the condensed low-boiling-point substance to the low-boiling-point substance storage tank for storage.

In order to facilitate the storage of purified silicon tetrachloride, the preferred rectification purification unit further comprises a purified silicon tetrachloride storage tank, wherein the purified silicon tetrachloride storage tank is arranged at the bottom of the rectification tower 31, is connected with a liquid phase outlet of the rectification tower 31 and is used for storing purified silicon tetrachloride discharged by the rectification tower 31.

In order to further purify the silicon tetrachloride, the preferred rectification purification unit further comprises a reboiler 33, wherein the reboiler 33 is arranged on a pipeline between the rectification tower 31 and a purified silicon tetrachloride storage tank, and an outlet of the reboiler 33 is further connected with the rectification tower 31 and is used for providing a heat source for the rectification tower 31, evaporating liquid phase materials in the rectification tower 31 into gas phase materials, and carrying out mass transfer in the rectification tower 31 so as to realize separation of the materials.

The specific type of the catalyst is not particularly limited, and the catalyst can catalyze methyl silicon chloride to react with hydrogen chloride to generate silicon tetrachloride and methane, and in order to further improve the catalytic efficiency, the catalyst preferably comprises a carrier and an active ingredient, and the mass content of the active ingredient in the catalyst is 1-30%; the carrier is molecular sieve or zeolite, and the active ingredient is selected from mixed active ingredients formed by any one or more of aluminum trichloride, copper chloride, zinc chloride, aluminum, copper, palladium or platinum. The catalyst carrier contains a large number of pore channels, has larger surface area, provides the surface of the catalyst contacted with a medium, and enables methyl chlorosilanes such as trimethylchlorosilane, methyltrichlorosilane and the like to react with hydrogen chloride, si-C is broken to generate silicon tetrachloride and methane, so that the conversion of physical properties of impurities is realized, the silicon tetrachloride is a target product, separation is not needed, the difference of boiling points of the product methane and the silicon tetrachloride is large, the product and the silicon tetrachloride are easier to separate, and the removal of the methylchlorosilane is realized.

In order to facilitate filling of the catalyst in the gas phase reactor 21, the catalyst is preferably columnar or spherical and has a particle diameter of 1 to 5mm.

In order to further improve the reaction efficiency, it is preferable that the catalyst is in a bulk form inside the gas phase reactor 21, and the fluidity is good, so that the catalyst is more easily uniformly distributed inside the gas phase reactor 21, and channels and the like are avoided.

Preferably, the gas phase inlet at the bottom of the gas phase reactor 21 and the top extraction outlet are both provided with distributors, and each distributor is provided with a sealing piece, so that the catalyst inside the gas phase reactor 21 is sealed while medium gas is ensured to enter and exit, and the catalyst is prevented from entering a subsequent system.

It is preferable that the outside of the gas phase reactor 21 is provided with a jacket to maintain uniformity of temperature distribution inside the gas phase reactor 21 while medium such as hot water, steam or heat transfer oil can be stored.

In a second exemplary embodiment of the present application, there is also provided a method for purifying silicon tetrachloride, the method comprising: step S1, mixing silicon tetrachloride to be purified and hydrogen chloride to react under the action of a catalyst to obtain a mixture of the purified silicon tetrachloride and low-boiling-point substances; and S2, rectifying and separating the mixture of the purified silicon tetrachloride and the methane to obtain the purified silicon tetrachloride and the low-boiling-point substances, wherein the catalyst has the same meaning as that of the catalyst in the first exemplary embodiment, and the description is omitted.

According to the purification method of the silicon tetrachloride, firstly, the silicon tetrachloride to be purified and the hydrogen chloride are mixed for catalytic reaction, methyl silicon chloride serving as an impurity is catalytically converted into the silicon tetrachloride and the methane, and then, low-boiling-point substances such as the methane are separated through rectification purification, so that the purified silicon tetrachloride is obtained, the use of severe poison chlorine is avoided, the method is safe and environment-friendly, the process flow is short, and the method is suitable for industrial production.

In order to further increase the reaction efficiency, it is preferable in step S1 to mix and vaporize the silicon tetrachloride to be purified and then to carry out the reaction under the action of the catalyst. The gas phase catalytic reaction mode is adopted, gas molecules are small, molecules are more active, the atomic or molecular level mixing can be achieved, mass transfer is quicker, the catalyst is easier to enter and exit from micropores of the catalyst, methyl and hydrogen chloride are easier to collide, and the reaction efficiency is higher.

In order to further improve the vaporization efficiency, it is preferable that the vaporization is performed in the vaporizer 13, and the pressure of the vaporizer 13 is 50 to 1500kPa.

The above reaction is preferably performed in the gas phase reactor 21, and the gas phase reactor 21 has the same meaning as in the first exemplary embodiment described above, and will not be described again. In order to further improve the reaction efficiency, the pressure of the gas phase reactor 21 is preferably 50 to 1200kPa, and the pressure in the gas phase reactor 21 is the same as or similar to the pressure in the vaporizer 13, which is more advantageous for process control and reduces the fluctuation of the feed.

In order to further improve the efficiency of the rectification separation, the rectification separation is preferably carried out in a rectification column 31, the pressure of the rectification column 31 is preferably controlled to be 50-500 kPa, the reflux ratio is 7-20:1, the top temperature is 70-130 ℃, the theoretical plate number is 65-75, and a sieve plate or a filler is used to further improve the purity of the purified silicon tetrachloride.

In order to further promote the removal efficiency of impurities in the silicon tetrachloride to be purified, the molar ratio of the hydrogen chloride to the methyl in the silicon tetrachloride to be purified is preferably 1-2000 in the step S1, and especially when the molar ratio of the hydrogen chloride to the methyl in the silicon tetrachloride to be purified is 500-1000, the method is more beneficial to promoting the conversion of the methyl silicon chloride in the silicon tetrachloride to be purified into the silicon tetrachloride in energy saving.

In order to further ensure the purity of the purified silicon tetrachloride, the step S2 preferably further comprises reboiling the purified silicon tetrachloride and returning to continue the rectification separation.

The advantageous effects of the present application will be further described below with reference to examples and comparative examples.

Example 1

This embodiment provides a purification system for silicon tetrachloride, as shown in fig. 1, comprising: the device comprises a raw material supply unit, a catalytic reaction unit and a rectification purification unit, wherein the raw material supply unit comprises a hydrogen chloride storage tank 12, a silicon tetrachloride to be purified storage tank 11 and a vaporizer 13, and the hydrogen chloride storage tank 12 and the silicon tetrachloride to be purified storage tank 11 are respectively connected with the vaporizer 13; the vaporizer 13 is used for mixing and vaporizing silicon tetrachloride to be purified and hydrogen chloride into mixed gas to be reacted; the catalytic reaction unit comprises a gas phase reactor 21, wherein a catalyst is filled in the gas phase reactor, and the inlet of the gas phase reactor 21 is connected with a vaporizer 13 so as to react the mixed gas to be reacted under the action of the catalyst, thus obtaining a mixture of purified silicon tetrachloride and low-boiling-point substances; the rectification and purification unit comprises a rectification tower 31, a condenser 32, a low-boiling-point substance storage tank (not shown) and a purified silicon tetrachloride storage tank (not shown), wherein the rectification tower 31 is connected with an outlet of the gas phase reactor 21 and is used for mixing and separating purified silicon tetrachloride and low-boiling-point substances, the low-boiling-point substances are discharged from the gas phase treatment at the top of the rectification tower 31 and are discharged into the condenser 32 for condensation treatment and then are discharged into the low-boiling-point substance storage tank for storage; purified silicon tetrachloride is discharged from a liquid phase outlet at the bottom of the rectifying tower 31 and is conveyed to a purified silicon tetrachloride storage tank for storage.

In the purification system provided in this embodiment, the rectification purification unit further includes a reboiler 33, where the reboiler 33 is disposed on a pipeline between the rectification tower 31 and the purified silicon tetrachloride storage tank, and is configured to return purified silicon tetrachloride that does not meet requirements after reboiling treatment to the rectification tower 31 for further rectification separation.

In the embodiment, the catalyst is columnar or spherical, has the particle size of 1-5 mm, comprises a carrier and an active ingredient, and has the mass content of 1-30% in the catalyst; the carrier is molecular sieve or zeolite, and the active ingredient is selected from mixed active ingredients formed by any one or more of aluminum trichloride, copper chloride, zinc chloride, aluminum, copper, palladium or platinum. The catalyst carrier contains a large number of pore channels, has larger surface area, provides the surface of the catalyst contacted with a medium, and enables methyl chlorosilanes such as trimethylchlorosilane, methyltrichlorosilane and the like to react with hydrogen chloride, si-C is broken to generate silicon tetrachloride and methane, so that the conversion of physical properties of impurities is realized, the silicon tetrachloride is a target product, separation is not needed, the difference of boiling points of the product methane and the silicon tetrachloride is large, the product and the silicon tetrachloride are easier to separate, and the removal of the methylchlorosilane is realized.

In this embodiment, the catalyst is in a bulk form inside the gas phase reactor 21, so that the fluidity is good, the catalyst is more easily and uniformly distributed inside the gas phase reactor 21, and channels and the like are avoided.

In this embodiment, the gas phase inlet and the top extraction outlet are both provided with distributors, and each distributor is provided with a sealing member, so that the catalyst inside the gas phase reactor 21 is sealed while the medium gas is ensured to enter and exit, and the catalyst is prevented from entering the subsequent rectification and purification unit.

In the present embodiment, the outside of the gas phase reactor 21 is provided with a jacket in which a medium such as hot water, steam or heat conducting oil can be stored to maintain uniformity of the temperature distribution inside the gas phase reactor 21

Example 2

The embodiment provides a purification method of silicon tetrachloride, which is performed by adopting the purification system provided in embodiment 1, and specifically comprises the following steps:

(1) Introducing silicon tetrachloride to be purified and hydrogen chloride into a vaporizer 13 respectively for mixing and vaporizing to obtain mixed gas to be reacted; wherein the pressure in the vaporizer 13 is 500kPa, and the molar ratio of hydrogen chloride to methyl of the silicon tetrachloride to be purified is 800;

(2) Introducing the mixed gas to be reacted into a gas phase reactor 21 to react to generate purified silicon tetrachloride and methane, so as to obtain a mixture of the purified silicon tetrachloride and low-boiling-point substances, wherein the low-boiling-point substances comprise toluene, entrained hydrogen chloride and the like, the pressure in the gas phase reactor 21 is 500kPa so as to improve the flow stability of the mixed gas to be reacted entering the gas phase reactor 21, the catalyst comprises zeolite, the zeolite is loaded with aluminum trichloride, and the mass content of the aluminum trichloride is 30%;

(3) Introducing the mixture of the purified silicon tetrachloride and the low-boiling-point substances into a rectifying tower 31 in a gas phase form for rectifying separation, discharging the low-boiling-point substances from a gas phase outlet at the top of the rectifying tower 31, and discharging the purified silicon tetrachloride from a liquid phase outlet at the bottom of the rectifying tower 31; wherein, the pressure of the rectifying tower 31 is 500kPa, the reflux ratio is 15:1, the top temperature is 100 ℃, and the theoretical plate number is 70.

Example 3

This example is different from example 2 in that in step (1) and step (2), the pressure in vaporizer 13 and in gas-phase reactor 21 was 50kPa, and in step (3), the pressure in rectifying column 31 was also 50kPa.

Example 4

This example is different from example 2 in that in step (1), the pressure of the vaporizer 13 is 1500kPa, and the pressure in the gas phase reactor 21 is 1200kPa.

Example 5

This example differs from example 2 in that in step (1) the molar ratio of hydrogen chloride to methyl groups of the silicon tetrachloride to be purified is 1.

Example 6

This example differs from example 2 in that in step (1) the molar ratio of hydrogen chloride to methyl groups of the silicon tetrachloride to be purified is 500.

Example 7

This example differs from example 2 in that in step (1) the molar ratio of hydrogen chloride to methyl groups of the silicon tetrachloride to be purified is 1000.

Test examples

The purity of the purified silicon tetrachloride obtained by separation in examples 2 to 7 was measured by Gas Chromatography (GC), and the content of methylchlorosilane was measured by gas chromatography-mass spectrometer (GC-MS), as shown in table 1 below.

TABLE 1

From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the purification system catalytic reaction unit of silicon tetrachloride provided by the application is used for catalytically converting methyl chlorosilane in silicon tetrachloride to be purified into silicon tetrachloride and low-boiling substances, and the silicon tetrachloride and the low-boiling substances are separated by rectification through the rectification purification unit, so that purified silicon tetrachloride and low-boiling substances are obtained.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A purification system for silicon tetrachloride, the purification system comprising:

the catalytic reaction unit comprises a gas phase reactor (21), a catalyst is filled in the gas phase reactor (21), and the gas phase reactor (21) is used for mixing gas phase silicon tetrachloride to be purified with hydrogen chloride for reaction under the action of the catalyst to obtain a mixture of purified silicon tetrachloride and low-boiling-point substances;

the rectification purification unit comprises a rectification tower (31), and the rectification tower (31) is connected with the gas phase reactor (21) and is used for rectifying and separating the mixture of the purified silicon tetrachloride and the low-boiling-point substances to obtain the purified silicon tetrachloride and the low-boiling-point substances.

2. The purification system according to claim 1, characterized in that the purification system further comprises a raw material supply unit comprising a hydrogen chloride storage tank (12), a silicon tetrachloride to be purified storage tank (11) and a vaporizer (13), the hydrogen chloride storage tank (12) and the silicon tetrachloride to be purified storage tank (11) being connected to the vaporizer (13) respectively, the vaporizer (13) being connected to the gas phase reactor (21).

3. Purification system according to claim 1, characterized in that the rectification purification unit further comprises a low-boiling-point substance storage tank connected to the gas-phase outlet of the rectification column (31) for storing the low-boiling-point substance discharged from the rectification column (31);

preferably, a condenser (32) is arranged on a pipeline between the low-boiling-point substance storage tank and the rectifying tower (31).

4. The purification system according to claim 1, characterized in that the rectification purification unit further comprises a purified silicon tetrachloride storage tank connected to the liquid phase outlet of the rectification column (31) for storing the purified silicon tetrachloride discharged from the rectification column (31);

preferably, the rectification and purification unit further comprises a reboiler (33), wherein the reboiler (33) is arranged on a pipeline between the rectification tower (31) and the purified silicon tetrachloride storage tank, and the reboiler (33) is further connected with the rectification tower (31).

5. The purification system according to any one of claims 1 to 4, wherein the catalyst comprises a carrier and an active ingredient, and the mass content of the active ingredient in the catalyst is 1 to 30%; the carrier is a molecular sieve or zeolite, and the active ingredient is at least one of aluminum trichloride, copper chloride, zinc chloride, aluminum, copper, palladium or platinum;

preferably, the catalyst is columnar or spherical and has a particle size of 1-5 mm.

6. A method for purifying silicon tetrachloride, the method comprising:

step S1, mixing silicon tetrachloride to be purified and hydrogen chloride to react under the action of a catalyst to obtain a mixture of the purified silicon tetrachloride and low-boiling-point substances;

s2, rectifying and separating the mixture of the purified silicon tetrachloride and the low-boiling-point substances to obtain the purified silicon tetrachloride and the low-boiling-point substances;

wherein the catalyst has the same meaning as the catalyst of any one of the preceding claims 1 to 5.

7. The purification method according to claim 6, wherein the step S1 is carried out after the silicon tetrachloride to be purified and the hydrogen chloride are mixed and vaporized;

preferably, the pressure of the vaporization is 50 to 1500kPa;

preferably, the pressure of the reaction is 50 to 1200kPa.

8. The purification method according to claim 6, characterized in that step S2, the rectification separation is carried out in the rectification column (31);

preferably, the pressure of the rectifying tower (31) is 50-500 kPa, the reflux ratio is 7-20:1, the top temperature is 70-130 ℃, and the theoretical plate number is 65-75.

9. The purification process according to any one of claims 6 to 8, characterized in that in step S1 the molar ratio of hydrogen chloride to methyl groups in the silicon tetrachloride to be purified is from 1 to 2000, preferably from 500 to 1000.

10. The purification process according to any one of claims 6 to 8, characterized in that step S2 further comprises returning the purified silicon tetrachloride to continue the rectification separation after reboiling.

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