CN212740754U - System for purifying trichlorosilane - Google Patents
System for purifying trichlorosilane Download PDFInfo
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- CN212740754U CN212740754U CN202020217179.7U CN202020217179U CN212740754U CN 212740754 U CN212740754 U CN 212740754U CN 202020217179 U CN202020217179 U CN 202020217179U CN 212740754 U CN212740754 U CN 212740754U
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Abstract
The utility model discloses a system for purify trichlorosilane, which comprises a reaction rectifying tower and a composite rectifying tower. The reaction rectifying tower is internally provided with regular packing and a metal oxide microsphere layer which is positioned in the middle and/or the lower part of the reaction rectifying tower and is rich in hydroxyl on the surface, and the reaction rectifying tower is provided with a trichlorosilane crude product inlet, a first heavy component impurity outlet and a primary purified product outlet; the composite rectifying tower comprises a light component removal tower and a heavy component removal tower, the light component removal tower is provided with a light component removal raw material inlet, a light component impurity outlet and a light component removal purification product outlet, and the heavy component removal tower is provided with a heavy component removal raw material inlet, a second heavy component impurity outlet and a heavy component removal purification product outlet: the light material removal inlet is connected with the primary purified product outlet, and the light material removal purified product outlet is connected with the heavy material removal inlet; or the heavy material removal inlet is connected with the primary purified product outlet, and the heavy material removal purified product outlet is connected with the light material removal inlet. By adopting the system, a high-purity trichlorosilane product with the mass concentration of organic impurities not higher than 20ppbw can be obtained.
Description
Technical Field
The utility model belongs to the chemical industry field particularly, relates to a system for purifying trichlorosilane.
Background
Electronic grade polysilicon is mostly produced by adopting an improved Siemens method at present, industrial silicon powder and hydrogen chloride are reacted in a fluidized bed to generate trichlorosilane, then the trichlorosilane is purified by a rectification system, and the purified trichlorosilane is introduced into a reduction furnace to generate high-purity polysilicon.
Trichlorosilane is the most important raw material in producing electronic grade polysilicon, and is generally converted from silicon powder through trichlorosilane synthesis, hydrogenation reaction and the like, because the silicon powder production process is a coke reduction method, the silicon powder inevitably contains a large amount of carbon impurities, and CH is generated during synthesis or hydrogenation reaction3SiHCl2、(CH3)2SiCl2、CH3Cl、(CH3)2Cl2And the like organic impurities. Usually, the improved siemens method adopts rectification to purify trichlorosilane, but through simulation calculation and actual verification, the removal effect of partial organic matters in the rectification process is not high, which directly causes the carbon content of a polycrystalline silicon product to be higher and affects the production of downstream silicon wafers.
SUMMERY OF THE UTILITY MODEL
The present invention aims at solving at least one of the technical problems in the related art to a certain extent. Therefore, the utility model aims to provide a system for purifying trichlorosilane. The system is simple in structure, impurity removal efficiency and removal rate of organic impurities can be remarkably improved, other impurities cannot be introduced, and the high-purity trichlorosilane product with the mass concentration of the organic impurities being not higher than 20ppbw can be finally obtained.
The utility model discloses mainly provide based on following problem: at present, a multistage rectification method is mostly adopted to purify trichlorosilane, but part of organic impurities in trichlorosilane has a boiling point close to that of trichlorosilane, such as CH2Cl2And CH3SiHCl2And the carbon content of the polycrystalline silicon product is higher, and the downstream silicon wafer production is influenced.
Therefore, according to one aspect of the utility model, the utility model provides a system for purifying trichlorosilane. According to the utility model discloses an embodiment, this system includes:
the reaction rectifying tower is internally provided with regular packing and a metal oxide microsphere layer with the surface rich in hydroxyl, the metal oxide microsphere layer is positioned at the middle part and/or the lower part of the reaction rectifying tower, and the reaction rectifying tower is provided with a trichlorosilane crude product inlet, a first heavy component impurity outlet and a primary purified product outlet;
the composite rectifying tower comprises a light component removal tower and a heavy component removal tower, the light component removal tower is provided with a light component removal raw material inlet, a light component impurity outlet and a light component removal purification product outlet, and the heavy component removal tower is provided with a heavy component removal raw material inlet, a second heavy component impurity outlet and a heavy component removal purification product outlet: the light material removal inlet is connected with the primary purified product outlet, and the light material removal purified product outlet is connected with the heavy material removal inlet; or the heavy material removal inlet is connected with the primary purified product outlet, and the heavy material removal purified product outlet is connected with the light material removal inlet.
According to the utility model discloses above-mentioned embodiment's purification trichlorosilane's system can supply with trichlorosilane crude in advance to the reaction rectifying column in, utilizes the surface to be rich in the metal oxide microballon of firm hydroxyl and trichlorosilane crude reaction and obtains midbody HO-SiHCl2The intermediate will further react with CH3SiHCl2、CH2Cl2Reacting the impurities and converting the impurities into Cl2HSi-O-CH2SiHCl2、Cl2HSi-O-CHCl2Impurities with relatively large molecular weight and small molecular impurities such as HCl, hydrogen and the like are equally distributed, so that the boiling point of the organic impurities is obviously improved, and the organic impurities in the trichlorosilane can be removed as much as possible through heavy removal and rectification treatment during reaction; then the compound rectifying tower is used for continuously purifying the trichloro-benzene after the primary purificationAnd performing light component removal treatment and heavy component removal treatment on the hydrogen silicon, and further removing other light component impurities and heavy component impurities to obtain a high-purity trichlorosilane product. In conclusion, the system is simple in structure, impurity removal efficiency and organic matter impurity removal rate can be remarkably improved, other impurities cannot be introduced, and a high-purity trichlorosilane product with the organic matter impurity mass concentration not higher than 20ppb can be finally obtained.
In addition, the system for purifying trichlorosilane according to the embodiment of the present invention may further have the following additional technical features:
optionally, the system for purifying trichlorosilane comprises at least two reaction rectifying towers which are connected in series and/or in parallel.
Optionally, the structured packing is located above and/or below the layer of metal oxide microspheres.
Optionally, the primary purified product outlet is connected with the trichlorosilane crude product inlet.
Optionally, the middle part and/or the lower part of the reaction rectifying tower is/are provided with 2-3 metal oxide microsphere layers which are arranged at intervals up and down.
Optionally, the height of each metal oxide microsphere layer is 2-3 m independently.
Optionally, each of the metal oxide microsphere layers is independently provided with a liquid redistributor.
Optionally, the particle size of the metal oxide microspheres is 0.1-5 mm, preferably 0.5-2 mm.
Optionally, the metal oxide microspheres are TiO2Microspheres, ZrO2Microspheres, NiO microspheres, PtO microspheres, PdO microspheres and Al2O3At least one of microspheres.
Optionally, the composite rectification column comprises at least two sequentially connected heavy component removal columns and at least two sequentially connected light component removal columns.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a system for purifying trichlorosilane according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a system for purifying trichlorosilane according to another embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a system for purifying trichlorosilane according to another embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a system for purifying trichlorosilane according to another embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like 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 and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.
According to an aspect of the utility model, the utility model provides a system for purify trichlorosilane. According to an embodiment of the present invention, as shown in fig. 1 or fig. 2, the system includes: a reactive distillation column 100 and a composite distillation column 200. The system is simple in structure, impurity removal efficiency and organic matter impurity removal rate can be remarkably improved, other impurities cannot be introduced, and a high-purity trichlorosilane product with the organic matter impurity mass concentration not higher than 20ppb can be finally obtained. The system for purifying trichlorosilane is described in detail below with reference to fig. 1 to 4.
According to the embodiment of the utility model, be equipped with structured packing 110 and the metal oxide microsphere layer 120 that the surface is rich in hydroxyl in the reaction rectifying column 100, metal oxide microsphere layer 120 is located the middle part and/or the lower part of reaction rectifying column 100, and reaction rectifying column 100 has trichlorosilane crude entry 130, first heavy ends impurity export 140 and elementary purification product export 150. The reactive distillation tower is suitable for enabling trichlorosilane and metal oxide microspheres with surfaces rich in hydroxyl to be mixed and reacted and simultaneously carrying out de-heavy treatment, so that the hydroxyl, the trichlorosilane and organic matter impurities are reacted, reaction products are removed, and the primarily purified trichlorosilane is obtained.
The inventor surprisingly found that the intermediate HO-SiHCl formed by hydroxyl and trichlorosilane can be utilized2React with organic impurities to achieve the purpose of removing the organic impurities. Specifically, the metal oxide microspheres can be subjected to surface treatment by using an alkaline solution, so that the surfaces of the microspheres are rich in stable hydroxyl groups; when being mixed with the microspheres, trichlorosilane and hydroxyl on the surfaces of the microspheres can generate a displacement reaction shown in formula (1) to obtain an intermediate HO-SiHCl2And intermediate HO-SiHCl2Will rapidly react with CH3SiHCl2、CH2Cl2The impurities are subjected to reactions similar to the formula (2) and the formula (3) and the impurities are converted into Cl2HSi-O-CH2SiHCl2、Cl2HSi-O-CHCl2The impurities with relatively large molecular weight and the small molecular impurities such as HCl, hydrogen and the like are equally distributed, so that the boiling point of the organic impurities can be obviously improved, the impurities with relatively large molecular weight obtained by the impurity removal reaction can be rapidly removed through heavy-duty rectification treatment during the mixing reaction, the impurity removal reaction is promoted to be fully carried out in the forward direction, the impurity removal reaction is ensured to have higher conversion rate, and the organic impurities in the trichlorosilane can be removed as much as possible; and then, other light component impurities and heavy component impurities can be further removed by continuously performing light component removal treatment and heavy component removal treatment, so that the mass concentration of organic matter impurities in the finally obtained high-purity trichlorosilane product is ensured to be not higher than 20 ppb. Further, a small amount of water and/or alkaline substances possibly remaining on the surface of the metal oxide microspheres after surface treatment can further react with trichlorosilane to generate an intermediate HO-SiHCl2And other high boiling point substances are removed by impurity removal treatment; excess trace intermediate HO-SiHCl2Will continue to react with trichlorosilane to form a polymer formed by at least two trichlorosilane, and then remove impuritiesAnd (4) treating and removing. Wherein the reactions of formula (1), formula (2) and formula (3) are as follows:
X-OH+SiHCl3＝X-H+HO-SiHCl2formula (1)
HO-SiHCl2+CH2Cl2＝Cl2HSi-O-CHCl2+ HCl type (2)
HO-SiHCl2+CH3SiHCl2＝Cl2HSi-O-CH2SiHCl2+H2Formula (3)
In the formula (1), X is metal oxide microspheres.
According to a specific embodiment of the present invention, the structured packing 110 can be disposed above and/or below the metal oxide microsphere layer 120, and preferably, the structured packing 110 is disposed above and below the metal oxide microsphere layer 120, so as to further improve the heat and mass transfer efficiency in the reactive distillation column, and enable the mixing reaction and the de-heavy distillation reaction to be uniformly and efficiently performed.
According to another embodiment of the present invention, the middle and/or lower portion of the reactive distillation column 100 may be provided with 2-3 metal oxide microsphere layers 120 spaced up and down. The inventor discovers that trichlorosilane and when flowing through the metal oxide microsphere layer, can produce the race flow or wall flow phenomenon, lead to trichlorosilane and metal oxide microsphere's contact inhomogeneous, influence trichlorosilane and metal oxide microsphere surface hydroxyl's reaction efficiency, and then influence the edulcoration effect of organic matter, the utility model discloses in through the metal oxide microsphere layer that sets up interval arrangement about 2 ~ 3 layers, can make trichlorosilane produce liquid redistribution when flowing through adjacent two-layer microsphere layer, make more hydroxyl and trichlorosilane reaction, and then further improve the clearance of organic matter impurity. Preferably, each metal oxide microsphere layer 120 can be respectively and independently provided with a liquid redistributor, so that full contact between trichlorosilane and metal oxide microspheres can be further facilitated, impurity removal reaction is promoted to be smoothly carried out, and a better organic matter impurity removal effect can be achieved.
According to another embodiment of the present invention, the height of each metal oxide microsphere layer is 2-3 m independently. Therefore, the trichlorosilane can be further in full contact with the metal oxide microspheres, and a better organic matter impurity removal effect is achieved.
According to another embodiment of the present invention, the system for purifying trichlorosilane may include at least two reactive distillation columns 100, the reactive distillation columns 100 may be arranged in series and/or in parallel, and when a plurality of reactive distillation columns are arranged in series, the removal rate of organic impurities may be further improved; and when a plurality of reaction rectifying towers set up in parallel, can make a plurality of reaction rectifying towers use in turn, even if from this need change metal oxide microballon layer also can not influence purification efficiency, the utility model discloses in can further improve the purification efficiency and/or provide the effect to trichlorosilane through adopting above-mentioned setting.
According to yet another embodiment of the present invention, the metal oxide microspheres may be selected from TiO2Microspheres, ZrO2Microspheres, NiO microspheres, PtO microspheres, PdO microspheres and Al2O3At least one of the microspheres, the inventor finds that, under a slightly alkaline environment, an oxygen bridge on the surface of the metal oxide is broken, and hydroxyl groups are combined with active centers on the surface of the metal oxide to form more active surface hydroxyl groups, wherein the hydroxyl groups are stronger in combination with the metal oxide microspheres of the kind mentioned above, so that more hydroxyl groups can be attached to the surface of the metal oxide microspheres by performing surface treatment on the metal oxide microspheres. Preferably, the metal oxide microspheres may be selected from TiO2Microspheres, NiO microspheres and Al2O3At least one of the microspheres, thereby further facilitating enrichment of the metal oxide microsphere surface with robust hydroxyl groups.
According to another embodiment of the present invention, the particle size of the metal oxide microspheres can be 0.1-5 mm, and the inventors found that if the particle size of the metal oxide microspheres is too small, the porosity between the metal oxide microspheres is also low, which is not conducive to full contact between trichlorosilane and the metal oxide microspheres and affects the reaction efficiency; and if the particle diameter of metal oxide microballon is too big, will show to reduce its specific surface area, and then can the greatly reduced hydroxyl in the adhesion rate on metal oxide microballon surface, the utility model discloses in through controlling above-mentioned particle diameter scope, can show the reaction efficiency and the conversion rate that improve hydroxyl and trichlorosilane to more be favorable to getting rid of organic matter impurity. Preferably, the particle size of the metal oxide microspheres can be 0.5-2 mm, so that the specific surface area of the metal oxide microspheres can be further increased on the basis of ensuring that the metal oxide microspheres have sufficient porosity, the reaction efficiency and the conversion rate of hydroxyl and trichlorosilane can be further increased, and a better organic matter impurity removal effect can be achieved.
According to another embodiment of the present invention, the source of trichlorosilane in the present invention is not particularly limited, and those skilled in the art can select the trichlorosilane according to actual needs. For example, trichlorosilane can be obtained by a synthetic reaction of silicon and hydrogen chloride, and/or can be prepared by a hydrogenation reaction of silicon tetrachloride and hydrogen, and the like.
According to another embodiment of the present invention, the metal oxide microspheres can be placed in the reaction tank and surface-treated with an alkaline solution so as to enrich the surface of the metal oxide microspheres with stable hydroxyl groups. The pH value of the alkaline solution can be 7-9, and the inventor finds that if the pH value of the alkaline solution is too small, the alkaline solution is not beneficial to forming stable hydroxyl on the surface of the metal oxide microsphere, and can easily react with the metal oxide to form salt which is remained in the microsphere and then pollutes trichlorosilane; and if alkaline solution's pH value is too big, not only can make the stability of microballon surface hydroxyl not enough, form more not stable midbody enough easily, still can lead to the metal oxide microballon to take place the metathesis reaction, very easily to introducing other impurity in the trichlorosilane, the utility model discloses in through controlling above-mentioned pH value scope, not only can make metal oxide microballon surface be rich in firm hydroxyl, can also avoid producing other impurity. Preferably, the pH value of the alkaline solution can be 7.5-8.5, so that stable hydroxyl groups can be further formed on the surfaces of the metal oxide microspheres. In addition, the type of the alkaline solution in the present invention is not particularly limited, and those skilled in the art can select the alkaline solution according to actual needs, for example, the alkaline solution may be an alkaline solution or a strong base weak acid salt solution.
According to another embodiment of the present invention, the reacted microspheres can be regenerated by using an alkaline solution, so that the metal oxide microspheres can be recycled as hydroxyl carriers.
According to the utility model discloses a still another embodiment, can utilize water or alcohol to obtain the metal oxide microballon to wash surface treatment, then dry, can further improve the purity of the metal oxide microballon that the surface contains rich hydroxyl from this, avoid the introduction of other impurity.
According to the embodiment of the utility model, compound rectifying column 200 is including taking off light tower 210 and taking off heavy tower 220, takes off light tower 210 to have and takes off light raw materials entry 211, light component impurity export 212 and take off light purification product export 213, takes off heavy tower 220 to have and takes off heavy raw materials entry 221, heavy component impurity export 222 of second and takes off heavy purification product export 223: the light material removal inlet 211 is connected with the primary purified product outlet 150 and the light material removal purified product outlet 213 is connected with the heavy material removal inlet 221; alternatively, the heavies removal feed inlet 221 is connected to the primary purified product outlet 150 and the heavies removal purified product outlet 223 is connected to the lights removal feed inlet 211. The composite rectifying tower is suitable for continuously performing light component removal treatment and heavy component removal treatment on the primarily purified trichlorosilane obtained from the reactive rectifying tower to obtain the high-purity trichlorosilane, so that other light component impurities and heavy component impurities can be further removed, and the mass concentration of organic matter impurities in the finally obtained high-purity trichlorosilane product is ensured to be not higher than 20 ppb.
According to a specific embodiment of the present invention, as shown in fig. 3 or fig. 4, the composite distillation column 200 may include at least two heavy-removing columns 220 and at least two light-removing columns 210 connected in sequence, from which at least two-stage light-removing treatment and at least two-stage heavy-removing treatment may be performed on the primarily purified trichlorosilane, wherein the order of the dehydrogenation treatment and the heavy-removing treatment is not particularly limited, for example, at least two-stage heavy-removing treatment may be performed on the primarily purified trichlorosilane sequentially after at least two-stage heavy-removing treatment, and at least two-stage dehydrogenation treatment may be performed on the primarily purified trichlorosilane sequentially after at least two-stage heavy-removing treatment. Therefore, the purity of the finally prepared high-purity trichlorosilane can be further improved, and the mass concentration of organic impurities in the finally obtained high-purity trichlorosilane product is ensured to be not higher than 20 ppb.
According to another embodiment of the present invention, as shown in fig. 3 or fig. 4, the primary purified product outlet 150 may be connected to the trichlorosilane crude product inlet 130. The inventor finds that in order to avoid the problem that the conversion rate is not ideal in impurity removal reaction when trichlorosilane and microspheres with rich hydroxyl groups on the surface are mixed and subjected to de-emphasis treatment, on one hand, a reaction rectifying tower can be used for carrying out de-emphasis rectification treatment while the mixed reaction is carried out, so that impurities with relatively large molecular weight obtained in the impurity removal reaction can be rapidly removed, the impurity removal reaction is promoted to be carried out fully and forwardly, the high conversion rate of the impurity removal reaction is ensured, and organic matter impurities in trichlorosilane can be removed as much as possible; on the other hand, part of trichlorosilane obtained by de-weighting in the process can be refluxed, and is continuously mixed with microspheres with surfaces rich in hydroxyl groups for de-weighting treatment, so that the circulation volume is increased, the conversion rate of impurity removal reaction can be further improved, and the content of organic impurities in the finally prepared high-purity trichlorosilane is lower. Preferably, the reflux ratio can be 20-30 v%, and the inventor finds that the reflux ratio can be controlled to ensure that the impurity removal reaction has high conversion rate and the trichlorosilane purification process can be carried out efficiently, so that the purification efficiency and the purification effect of trichlorosilane can be further improved.
In summary, according to the system for purifying trichlorosilane of the present invention, the crude trichlorosilane can be supplied to the reactive distillation column in advance, and the intermediate HO-SiHCl is obtained by reacting the metal oxide microspheres with the surface rich in stable hydroxyl groups with the crude trichlorosilane2The intermediate will further react with CH3SiHCl2、CH2Cl2Reacting the impurities and converting the impurities into Cl2HSi-O-CH2SiHCl2、Cl2HSi-O-CHCl2Impurities with relatively large molecular weight and small molecular impurities such as HCl, hydrogen and the like are equally distributed, so that the boiling point of the organic impurities is obviously improved, and the organic impurities in the trichlorosilane can be removed as much as possible through heavy removal and rectification treatment during reaction; and then, continuously performing light component removal treatment and heavy component removal treatment on the primarily purified trichlorosilane by using a composite rectifying tower, and further removing other light component impurities and heavy component impurities to obtain a high-purity trichlorosilane product. In fact, the system for purifying trichlorosilane in the utility model can be understood as introducing a reaction rectification device before the existing multistage rectification system, and just because of the arrangement of the device, not only the removal efficiency and effect of organic impurities can be obviously improved, but also the original multistage rectification system can be simplified, and the number of the original de-weighting or de-weighting towers can be reduced. In conclusion, the system is simple in structure, impurity removal efficiency and organic matter impurity removal rate can be remarkably improved, other impurities cannot be introduced, and a high-purity trichlorosilane product with the organic matter impurity mass concentration not higher than 20ppb can be finally obtained.
In order to facilitate understanding of the system for purifying trichlorosilane according to the embodiment of the present invention, a method for purifying trichlorosilane by using the system for purifying trichlorosilane will be described in detail below. According to the utility model discloses an embodiment, this method includes: (1) carrying out surface treatment on the metal oxide microspheres by using an alkaline solution so as to form hydroxyl on the surfaces of the metal oxide microspheres; (2) mixing trichlorosilane with the microspheres obtained in the step (1) and carrying out de-duplication treatment so as to enable hydroxyl to react with trichlorosilane and organic impurities and remove reaction products, thereby obtaining primarily purified trichlorosilane; (3) and (3) performing light weight removal treatment and heavy weight removal treatment on the trichlorosilane obtained in the step (2) so as to obtain high-purity trichlorosilane. The method has simple process and high efficiency, and can also obviously improve the removal rate of organic impurities, and finally obtain the high-purity trichlorosilane product with the mass concentration of the organic impurities not higher than 20 ppb. The method for purifying trichlorosilane according to the above embodiment of the present invention will be described in detail below.
S100, adopting alkaline solution to carry out surface treatment on the metal oxide microspheres to form hydroxyl on the surfaces of the metal oxide microspheres
According to the embodiment of the utility model, the inventor unexpectedly discovers that the intermediate HO-SiHCl formed by hydroxyl and trichlorosilane can be utilized2The method can be used for removing organic impurities by reacting with the organic impurities, wherein the metal oxide microspheres can be subjected to surface treatment by using an alkaline solution so that the surfaces of the microspheres are rich in stable hydroxyl groups, and then the microspheres with the hydroxyl groups are mixed with trichlorosilane for impurity removal and purification. The utility model discloses in through utilizing the surface to be rich in the metal oxide microballon and the trichlorosilane mixed reaction of firm hydroxyl, not only can effectively avoid the introduction of other impurity, can also utilize alkaline solution to regenerate the microballon after the reaction, make metal oxide microballon use as hydroxyl carrier cycle.
According to a specific embodiment of the present invention, the pH of the alkaline solution may be 7-9, and the inventors found that if the pH of the alkaline solution is too small, it is not only unfavorable to form stable hydroxyl on the surface of the metal oxide microsphere, but also easy to react with the metal oxide itself to form salt, which remains in the microsphere and then pollutes trichlorosilane; and if alkaline solution's pH value is too big, not only can make the stability of microballon surface hydroxyl not enough, form more not stable midbody enough easily, still can lead to the metal oxide microballon to take place the metathesis reaction, very easily to introducing other impurity in the trichlorosilane, the utility model discloses in through controlling above-mentioned pH value scope, not only can make metal oxide microballon surface be rich in firm hydroxyl, can also avoid producing other impurity. Preferably, the pH value of the alkaline solution can be 7.5-8.5, so that stable hydroxyl groups can be further formed on the surfaces of the metal oxide microspheres.
According to another embodiment of the present invention, the type of the alkaline solution is not particularly limited, and can be selected by those skilled in the art according to actual needs, for example, the alkaline solution can be alkaline solution or strong base weak acid salt solution.
According to the utility model discloses a still another embodiment, can utilize water or alcohol to obtain the metal oxide microballon to wash surface treatment, then dry, can further improve the purity of the metal oxide microballon that the surface contains rich hydroxyl from this, avoid the introduction of other impurity.
According to yet another embodiment of the present invention, the metal oxide microspheres may be selected from TiO2Microspheres, ZrO2Microspheres, NiO microspheres, PtO microspheres, PdO microspheres and Al2O3At least one of the microspheres, the inventor finds that, under a slightly alkaline environment, an oxygen bridge on the surface of the metal oxide is broken, and hydroxyl groups are combined with active centers on the surface of the metal oxide to form more active surface hydroxyl groups, wherein the hydroxyl groups are stronger in combination with the metal oxide microspheres of the kind mentioned above, so that more hydroxyl groups can be attached to the surface of the metal oxide microspheres by performing surface treatment on the metal oxide microspheres. Preferably, the metal oxide microspheres may be selected from TiO2Microspheres, NiO microspheres and Al2O3At least one of the microspheres, thereby further facilitating enrichment of the metal oxide microsphere surface with robust hydroxyl groups.
According to another embodiment of the present invention, the particle size of the metal oxide microspheres can be 0.1-5 mm, and the inventors found that if the particle size of the metal oxide microspheres is too small, the porosity between the metal oxide microspheres is also low, which is not conducive to full contact between trichlorosilane and the metal oxide microspheres and affects the reaction efficiency; and if the particle diameter of metal oxide microballon is too big, will show to reduce its specific surface area, and then can the greatly reduced hydroxyl in the adhesion rate on metal oxide microballon surface, the utility model discloses in through controlling above-mentioned particle diameter scope, can show the reaction efficiency and the conversion rate that improve hydroxyl and trichlorosilane to more be favorable to getting rid of organic matter impurity. Preferably, the particle size of the metal oxide microspheres can be 0.5-2 mm, so that the specific surface area of the metal oxide microspheres can be further increased on the basis of ensuring that the metal oxide microspheres have sufficient porosity, the reaction efficiency and the conversion rate of hydroxyl and trichlorosilane can be further increased, and a better organic matter impurity removal effect can be achieved.
S200, mixing trichlorosilane with the microspheres obtained in the step S100, performing de-duplication treatment to enable hydroxyl groups to react with trichlorosilane and organic impurities and removing reaction products to obtain primarily purified trichlorosilane
According to the embodiment of the utility model, when trichlorosilane is mixed with microspheres with rich hydroxyl on the surface, the trichlorosilane and the hydroxyl on the surfaces of the microspheres can generate the replacement reaction as shown in formula (1) to obtain the intermediate HO-SiHCl2And intermediate HO-SiHCl2Will further react with CH3SiHCl2、CH2Cl2The impurities are subjected to similar reactions as shown in formula (2) and formula (3), and impurities with relatively small molecular weight are converted into Cl2HSi-O-CH2SiHCl2、Cl2HSi-O-CHCl2Impurities with relatively large molecular weight and small molecular impurities such as HCl, hydrogen and the like are equally distributed, so that the boiling point of organic impurities can be obviously improved, the impurities with relatively large molecular weight obtained by impurity removal reaction can be rapidly removed through heavy removal rectification treatment during reaction, the impurity removal reaction is promoted to be fully carried out in the forward direction, and the high conversion rate of the impurity removal reaction is ensured; since the content of organic impurities in the trichlorosilane is low, the removal of the organic impurities by means of the trichlorosilane does not affect the yield of the purified trichlorosilane. Wherein the reactions of formula (1), formula (2) and formula (3) are as follows:
X-OH+SiHCl3＝X-H+HO-SiHCl2formula (1)
HO-SiHCl2+CH2Cl2＝Cl2HSi-O-CHCl2+ HCl type (2)
HO-SiHCl2+CH3SiHCl2＝Cl2HSi-O-CH2SiHCl2+H2Formula (3)
In the formula (1), X is metal oxide microspheres.
According to a specific embodiment of the present invention, the source of trichlorosilane in the present invention is not particularly limited, and those skilled in the art can select the trichlorosilane according to actual needs. For example, trichlorosilane can be obtained by a synthetic reaction of silicon and hydrogen chloride, and/or can be prepared by a hydrogenation reaction of silicon tetrachloride and hydrogen, and the like.
According to the utility model discloses a still another embodiment, when trichlorosilane mixes and the microballon that the surface is rich in hydroxyl and carries out the heavy processing of taking off, in order to avoid the edulcoration reaction to have the unsatisfactory problem of conversion rate probably, can carry out the heavy rectification processing of taking off in the mixed reaction on the one hand, can detach the impurity that the molecular weight that the edulcoration reaction obtained is great relatively from this fast, impel the abundant forward of edulcoration reaction to go on, ensure that the edulcoration reaction has higher conversion rate to organic matter impurity in the trichlorosilane can be got rid of as much as possible; on the other hand, part of trichlorosilane obtained by de-weighting in the process can be refluxed, and is continuously mixed with microspheres with surfaces rich in hydroxyl groups for de-weighting treatment, so that the circulation volume is increased, the conversion rate of impurity removal reaction can be further improved, and the content of organic impurities in the finally prepared high-purity trichlorosilane is lower. Preferably, the reflux ratio can be 20-30 v%, and the inventor finds that the reflux ratio can be controlled to ensure that the impurity removal reaction has high conversion rate and the trichlorosilane purification process can be carried out efficiently, so that the purification efficiency and the purification effect of trichlorosilane can be further improved.
S300, performing light weight removal treatment and heavy weight removal treatment on the trichlorosilane obtained in the step S200 to obtain high-purity trichlorosilane
According to the embodiment of the utility model, through further carrying out the lightness-removing treatment and the weight-removing treatment to the trichlorosilane of the primary purification obtained through the mixed reaction and the weight-removing rectification treatment, other light component impurities and heavy component impurities can be further removed, and the mass concentration of organic matter impurities in the finally obtained high-purity trichlorosilane product is ensured not to be higher than 20 ppb.
According to the utility model discloses a specific embodiment, can further carry out at least two-stage to the trichlorosilane of the elementary purification who obtains through mixing reaction and heavy rectification processing and take off light processing and at least two-stage heavy processing of taking off, wherein, the order of dehydrogenation processing and heavy processing of taking off is not special restriction, for example can carry out at least two-stage heavy processing of taking off again after the trichlorosilane of elementary purification carries out at least two-stage dehydrogenation in proper order, also can carry out at least two-stage dehydrogenation processing again after the trichlorosilane of elementary purification carries out at least two-stage heavy processing in proper order again, can further improve the purity of the high-purity trichlorosilane of final preparation from this, ensure that the mass concentration of organic matter impurity is not higher than 20ppb in the high-purity trichlorosilane product that finally obtains.
To sum up, the method for purifying trichlorosilane of the embodiment of the present invention at least has the following advantages: the surface of the metal oxide microsphere is subjected to surface treatment by using an alkaline solution in advance, so that the surface of the microsphere is rich in stable hydroxyl; when trichlorosilane is mixed with the microspheres, trichlorosilane and hydroxyl on the surfaces of the microspheres can generate a displacement reaction to obtain an intermediate HO-SiHCl2And intermediate HO-SiHCl2Will rapidly react with CH3SiHCl2、CH2Cl2Reacting the impurities and converting the impurities into Cl2HSi-O-CH2SiHCl2、Cl2HSi-O-CHCl2The impurities with relatively large molecular weight and the small molecular impurities such as HCl, hydrogen and the like are equally distributed, so that the boiling point of the organic impurities is obviously improved, the impurities with relatively large molecular weight obtained by impurity removal reaction can be rapidly removed through heavy-duty rectification treatment during the mixing reaction, the impurity removal reaction is promoted to be fully carried out in the forward direction, the high conversion rate of the impurity removal reaction is ensured, and the organic impurities in the trichlorosilane can be removed as much as possible; then, other light component impurities and heavy component impurities can be further removed by continuously carrying out lightness-removing treatment and weight-removing treatment, so that the mass concentration of organic matter impurities in the finally obtained high-purity trichlorosilane product is ensured to be not higher than 20 ppb; further, a small amount of water and/or alkaline substances possibly remaining on the surface of the metal oxide microspheres after surface treatment can further react with trichlorosilane to generate an intermediate HO-SiHCl2And other high boiling point substances are removed by impurity removal treatment; excess trace intermediate HO-SiHCl2The reaction with trichlorosilane is continued to form a polymer formed by at least two trichlorosilane, and the polymer is further removed by impurity removal treatment. In addition, the mixed reaction of the metal oxide microspheres with the surfaces rich in stable hydroxyl and trichlorosilane can effectively avoid the introduction of other impurities, and the microspheres after the reaction can be regenerated, and the trichlorosilane is adoptedThe content of organic impurities in silicon is low, and the removal of the organic impurities by means of trichlorosilane does not affect the yield of purified trichlorosilane. Therefore, compared with the traditional process, the method has the advantages of simple process and high efficiency, and can also obviously improve the removal rate of organic impurities, obtain a high-purity trichlorosilane product with the mass concentration of the organic impurities not higher than 20ppb, and greatly reduce the carbon content of the trichlorosilane product.
The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.
Example 1
(1) Carrying out surface treatment on the metal oxide microspheres by adopting alkaline solution to form hydroxyl on the surfaces of the metal oxide microspheres, wherein the metal oxide microspheres are TiO2Microspheres, NiO microspheres and Al2O3Microspheres, wherein the particle size of the metal oxide microspheres is 1 mm; the alkaline solution is NaOH solution with pH value of 7.5, the surface treatment process is to put the microspheres into the alkaline solution and maintain the microspheres at 45 ℃ for about 2 hours.
(2) Placing the microspheres obtained in the step (1) in a reaction rectifying tower to form 2 metal oxide microsphere layers with the height of 3m, supplying trichlorosilane into the reaction rectifying tower to mix with the metal oxide microspheres and carrying out de-heavy treatment, so that hydroxyl, trichlorosilane and organic matter impurities react, and reaction products are removed to obtain primarily purified trichlorosilane.
(3) And (3) sequentially supplying the primarily purified trichlorosilane obtained in the step (2) to a light component removal tower, a heavy component removal tower and a heavy component removal tower for light component removal treatment and heavy component removal treatment to obtain high-purity trichlorosilane, wherein the mass concentration of organic impurities in the high-purity trichlorosilane is 8.5 ppb.
Example 2
(1) Carrying out surface treatment on the metal oxide microspheres by adopting an alkaline solution to form hydroxyl on the surfaces of the metal oxide microspheres, wherein the metal oxide microspheres are NiO microspheres and Al2O3Microspheres, the particle size of the metal oxide microspheres is 1.8 mm; the alkaline solution is NaOH solution with pH value of 8.1, and the surface of the alkaline solution isThe physical process is to put the microspheres into an alkaline solution and maintain the microspheres at 45 ℃ for about 1.5 hours.
(2) Placing the microspheres obtained in the step (1) in a reaction rectifying tower to form 3 metal oxide microsphere layers with the height of 2m, supplying trichlorosilane into the reaction rectifying tower to mix with the metal oxide microspheres and carrying out de-heavy treatment, so that hydroxyl, trichlorosilane and organic matter impurities react, and reaction products are removed to obtain primarily purified trichlorosilane.
(3) And (3) refluxing a part of the primarily purified trichlorosilane obtained in the step (2) to the step (2) with a reflux ratio of 20-30 v%, and sequentially supplying the rest of the primarily purified trichlorosilane to a lightness-removing tower, a weight-removing tower and a weight-removing tower for lightness-removing treatment and weight-removing treatment to obtain the high-purity trichlorosilane, wherein the mass concentration of organic impurities in the high-purity trichlorosilane is 12 ppb.
Example 3
(1) Carrying out surface treatment on the metal oxide microspheres by adopting alkaline solution to form hydroxyl on the surfaces of the metal oxide microspheres, wherein the metal oxide microspheres are TiO2The particle size of the metal oxide microspheres is 0.7 mm; the alkaline solution is NaOH solution with pH value of 7.5, the surface treatment process is to put the microspheres into the alkaline solution and maintain the microspheres at 45 ℃ for about 1.5 hours.
(2) Placing the microspheres obtained in the step (1) in a reaction rectifying tower to form 3 metal oxide microsphere layers with the height of 2m, supplying trichlorosilane into the reaction rectifying tower to mix with the metal oxide microspheres and carrying out de-heavy treatment, so that hydroxyl, trichlorosilane and organic matter impurities react, and reaction products are removed to obtain primarily purified trichlorosilane.
(3) And (3) refluxing a part of the primarily purified trichlorosilane obtained in the step (2) to the step (2) with a reflux ratio of 20-30 v%, and sequentially supplying the rest of the primarily purified trichlorosilane to a de-heavy tower, a de-light tower and a de-light tower for de-heavy treatment and dehydrogenation treatment to obtain the high-purity trichlorosilane, wherein the mass concentration of organic impurities in the high-purity trichlorosilane is 9.1 ppb.
Comparative example 1
The difference from the embodiment 2 is that trichlorosilane is directly supplied to a lightness-removing tower, a heaving-removing tower and a heaving-removing tower for lightness-removing treatment and heaving-removing treatment, so that high-purity trichlorosilane is obtained, wherein the mass concentration of organic impurities in the high-purity trichlorosilane is 82 ppb.
In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In the present invention, unless otherwise expressly stated or limited, the term "connected" is to be understood in a broad sense, e.g. fixedly connected, detachably connected, or integrated; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art. In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the scope of the present invention.
Claims (9)
1. A system for purifying trichlorosilane is characterized by comprising the following steps:
the reaction rectifying tower is internally provided with regular packing and a metal oxide microsphere layer with the surface rich in hydroxyl, the metal oxide microsphere layer is positioned at the middle part and/or the lower part of the reaction rectifying tower, and the reaction rectifying tower is provided with a trichlorosilane crude product inlet, a first heavy component impurity outlet and a primary purified product outlet;
the composite rectifying tower comprises a light component removal tower and a heavy component removal tower, the light component removal tower is provided with a light component removal raw material inlet, a light component impurity outlet and a light component removal purification product outlet, and the heavy component removal tower is provided with a heavy component removal raw material inlet, a second heavy component impurity outlet and a heavy component removal purification product outlet: the light material removal inlet is connected with the primary purified product outlet, and the light material removal purified product outlet is connected with the heavy material removal inlet; or the heavy material removal inlet is connected with the primary purified product outlet, and the heavy material removal purified product outlet is connected with the light material removal inlet.
2. The system of claim 1, comprising at least two of the reactive distillation columns, the reactive distillation columns being arranged in series and/or in parallel.
3. The system of claim 1 or 2, wherein the structured packing is located above and/or below the layer of metal oxide microspheres.
4. The system of claim 3, wherein the primary purified product outlet is connected to the trichlorosilane crude inlet.
5. The system according to claim 1 or 4, wherein the middle part and/or the lower part of the reactive distillation column is/are provided with 2-3 metal oxide microsphere layers which are arranged at intervals up and down.
6. The system of claim 5, wherein each layer of metal oxide microspheres has a height of 2-3 m.
7. The system of claim 6, wherein each of the metal oxide microsphere layers is independently provided with a liquid redistributor.
8. The system of claim 1 or 7, wherein the metal oxide microspheres have a particle size of 0.1 to 5 mm.
9. The system of claim 1, wherein the composite rectification column comprises at least two sequentially connected de-heavies columns and at least two sequentially connected de-lighters columns.
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