Adsorbents, methods, and systems for chlorosilane purification

Abstract

The application discloses an adsorbent, a method and a system for chlorosilane purification, the adsorbent comprising a functionalized activated carbon adsorbent, an organic group functionalized mesoporous molecular sieve adsorbent and a functional group modified multi-walled carbon nanotube adsorbent, the functionalized activated carbon adsorbent being one or more of modified activated carbons containing imidazole groups or benzyl groups or ketoxime groups; the organic group functionalized mesoporous molecular sieve adsorbent being one or more of modified mesoporous molecular sieves containing chlorobenzene groups or geminal amidoxime groups or pyrrozine groups; and the functional group modified multi-walled carbon nanotube adsorbent being one or more of modified multi-walled carbon nanotubes containing hydrazine groups or geminal dinitrile groups or quinoline groups. The adsorbent has a large specific surface area and strong selectivity, can effectively remove phosphorus impurities, boron impurities and metal impurities in chlorosilane, and can avoid problems such as that the cleanliness of a resin adsorbent cannot be effectively controlled, high cost and the risk of thermal decomposition compared with traditional technologies.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chlorosilane purification, and particularly relates to an adsorbent for chlorosilane purification, and a method and system for chlorosilane purification using the adsorbent. BACKGROUND

[0002] Chlorosilane is a main raw material in the production process of polysilicon, and contains many types and amounts of impurities. Non-metallic impurities mainly include boron, phosphorus and carbon, and metallic impurities mainly include iron, chromium, nickel, copper, zinc and sodium.

[0003] Boron and phosphorus impurities are two types of impurities that are difficult to remove in the production process of polysilicon. The two types of impurities remaining in polysilicon can reduce the minority carrier lifetime as a recombination center, and affect the conversion efficiency of solar cells. Similarly, the presence of metallic impurities can seriously affect the quality of polysilicon products. Metallic impurities generally exist in the form of interstitial state, substitution state, complex or precipitation, often introduce additional electrons or holes, change the carrier concentration of the silicon wafer, and can also become a recombination center to greatly reduce the minority carrier lifetime. In addition, due to the presence of a large number of defects such as dislocations in polysilicon, metallic impurities are prone to form metallic precipitates at these defects, causing serious damage to the performance of the silicon wafer.

[0004] At present, the technology for purifying chlorosilane in the industry is mostly multi-stage rectification technology. However, this technology has the problems of high energy consumption and high investment, which can cause a certain degree of pressure on the operation and production of enterprises. In order to solve this problem, a few enterprises have tried to purify chlorosilane by combining rectification technology with adsorption technology. The key of this technology is the selection of adsorbent. These enterprises have tried to use resin as an adsorbent to adsorb impurities in chlorosilane. However, due to the inability to effectively control the cleanliness of the resin itself, the resin can contaminate the chlorosilane material, thereby affecting the purity of the purified chlorosilane. In addition, the resin not only has high procurement cost, but also has the risk of thermal decomposition at high temperature during operation as an adsorbent, which can cause certain safety hazards to the safe and stable operation of the technology. SUMMARY

[0005] The technical problem to be solved by the present application is to provide an adsorbent for chlorosilane purification, and a method and system for chlorosilane purification using the adsorbent, which can effectively remove phosphorus impurities, boron impurities and metallic impurities in chlorosilane, improve the purity of chlorosilane, and avoid the problems of ineffective control of the cleanliness of resin adsorbent, high cost and risk of thermal decomposition compared with traditional technologies.

[0006] The technical solution of the present application to solve the above technical problems is:

[0007] According to a first aspect of the present application, there is provided an adsorbent for chlorosilane purification, comprising a functionalized activated carbon adsorbent, an organic group functionalized mesoporous molecular sieve adsorbent, and a functional group modified multi-walled carbon nanotube adsorbent, wherein:

[0008] The functionalized activated carbon adsorbent is one or more of modified activated carbons comprising imidazole groups or benzyl groups or ketoxime groups;

[0009] The organic group functionalized mesoporous molecular sieve adsorbent is one or more of mesoporous molecular sieves comprising chlorobenzene groups or geminal amidoxime groups or pyrrolizine groups;

[0010] The functional group modified multi-walled carbon nanotube adsorbent is one or more of multi-walled carbon nanotubes comprising hydrazine groups or geminal dinitrile groups or quinoline groups.

[0011] Preferably, the functional group content of the functionalized activated carbon adsorbent is 3-7 mmol / g, the specific surface area is 460-1390 m 2 / g, and the pore size is 5-73 nm.

[0012] Preferably, the organic group content of the organic group functionalized mesoporous molecular sieve adsorbent is 1-5 mmol / g, the specific surface area is 750-1500 m 2 / g, and the pore size is 2-50 nm.

[0013] Preferably, the organic group content of the functional group modified multi-walled carbon nanotube adsorbent is 2-5 mmol / g, the specific surface area is 280-1270 m 2 / g, and the pore size is 2-20 nm.

[0014] According to a second aspect of the present application, there is provided a method for chlorosilane purification, comprising:

[0015] S1, adsorbing chlorosilane with the functionalized activated carbon adsorbent described above to remove phosphorus impurities, to obtain a first feed liquid;

[0016] S2, performing crude distillation purification on the first feed liquid to separate dichlorodihydrogen silicon and silicon tetrachloride, to obtain liquid-phase crude trichlorohydrogen silicon;

[0017] S3, adsorbing the liquid-phase crude trichlorohydrogen silicon with the organic group functionalized mesoporous molecular sieve adsorbent described above to remove boron impurities, to obtain a second feed liquid;

[0018] S4, performing rectification purification on the second feed liquid to further separate dichlorodihydrogen silicon and silicon tetrachloride, to obtain refined trichlorohydrogen silicon;

[0019] S5, the refined trichlorosilane is adsorbed by the above-mentioned functional group modified multi-walled carbon nanotube adsorbent to remove metal impurities, to obtain a third feed liquid;

[0020] S6, the third feed liquid is subjected to re-distillation purification to obtain trichlorosilane products.

[0021] Preferably, the temperature of the crude distillation purification process in step S2 is 56-107℃, and the pressure is 0.2-0.7MPa.

[0022] Preferably, the temperature of the distillation purification process in step S4 is 60-101℃, and the pressure is set to 0.1-0.49MPa.

[0023] Preferably, the temperature of the re-distillation purification process in step S6 is 96-105℃, and the pressure is set to 0.4-0.6MPa.

[0024] Preferably, before step S1, the method further comprises:

[0025] The low-boiling phosphorus impurities in the feed liquid are converted into high-boiling phosphorus impurities through chlorination and phosphorylation reactions of the low-boiling phosphorus impurities with chlorine gas under the action of a catalyst.

[0026] Preferably, the catalyst is one or more of NaAlCl4 / activated carbon, FeN4 / C3N4, and KAlBr4 / zeolite.

[0027] Preferably, the active substance content in the catalyst is 3%-8%, and the specific surface area of the catalyst is 550-965m 2 / g.

[0028] According to a third aspect of the present application, a system for chlorosilane purification is provided for the above-mentioned method for chlorosilane purification, which comprises a first adsorption device, a crude distillation device, a second adsorption device, a distillation device, a third adsorption device, and a re-distillation device, wherein:

[0029] The first adsorption device is filled with the above-mentioned functionalized activated carbon adsorbent, which is used to remove phosphorus impurities in chlorosilane to obtain a first feed liquid;

[0030] The crude distillation device is connected to the first adsorption device, and is used to receive the first feed liquid and subject it to crude distillation purification to obtain liquid-phase crude trichlorosilane;

[0031] The second adsorption device is connected to the crude distillation device, and the second adsorption device is filled with the above-mentioned organic group functionalized mesoporous molecular sieve adsorbent, which is used to receive the liquid-phase crude trichlorosilane and remove boron impurities to obtain a second feed liquid;

[0032] The rectification device is connected with the second adsorption device and used for receiving the second feed liquid and rectifying and purifying the same to obtain refined trichlorosilane;

[0033] The third adsorption device is connected with the rectification device and filled with the functional group modified multi-walled carbon nanotube adsorbent, which is used for receiving the refined trichlorosilane and removing metal impurities to obtain a third feed liquid.

[0034] The re-rectification device is connected with the third adsorption device and used for receiving the third feed liquid and re-rectifying and purifying the same to obtain trichlorosilane products.

[0035] Preferably, the system further comprises a low-temperature chlorination device connected with the first adsorption device and used for low-temperature chlorination treatment of chlorosilane, so that the low-boiling phosphorus impurities in the feed liquid are chlorinated and phosphorylated under the action of a catalyst to convert the low-boiling phosphorus impurities into high-boiling phosphorus impurities, and then the treated feed liquid is introduced into the first adsorption device.

[0036] Beneficial effects:

[0037] (1) The functionalized activated carbon adsorbent is used to adsorb and treat chlorosilane, so that the phosphorus impurities in the chlorosilane can be efficiently removed;

[0038] (2) The organic group functionalized mesoporous molecular sieve adsorbent is used to adsorb and treat chlorosilane, so that the boron impurities in the chlorosilane can be efficiently removed;

[0039] (3) The functional group modified multi-walled carbon nanotube is used to adsorb and treat chlorosilane, so that the metal impurities such as iron, copper, chromium, nickel, zinc and sodium in the chlorosilane can be efficiently removed;

[0040] (4) The rectification technology and the adsorption technology are combined, and through the synergistic effect of the rectification technology and the adsorption technology, the phosphorus, boron, silicon tetrachloride and metal impurities that can affect the quality of polysilicon products in chlorosilane are effectively removed, the purity of chlorosilane is improved, the polysilicon produced by using the trichlorosilane product purified by the method can effectively improve the quality of polysilicon, and the energy consumption of the crude distillation and rectification process can be reduced to achieve the purpose of reducing cost and increasing efficiency;

[0041] (5) The low-temperature chlorination treatment of chlorosilane can convert the low-boiling phosphorus impurities in the chlorosilane into high-boiling phosphorus impurities, which can further improve the removal rate of phosphorus impurities and reduce the energy consumption of the subsequent crude distillation and rectification process;

[0042] (6) The method and system of the present application do not need to pretreat the purified chlorosilane material, thus not only simplifying the process flow, but also reducing the production cost;

[0043] (7) Compared with the prior art, the present application can avoid the problems of the resin adsorbent cleanliness being unable to be effectively controlled, high cost, and risk of thermal decomposition, and is safe and stable. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of the system for chlorosilane purification of the embodiment of the present application.

[0045] In the figure: 1 - low-temperature chlorination device; 2 - first adsorption device; 3 - crude distillation first-stage column; 4 - crude distillation second-stage column; 5 - crude distillation third-stage column; 6 - second adsorption device; 7 - rectification first-stage column; 8 - rectification second-stage column; 9 - third adsorption device; 10 - re-rectification device. DETAILED DESCRIPTION

[0046] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions in the present application will be described in detail below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the protection scope of the present application.

[0047] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience and simplification of the description, and are not intended to indicate or imply that the indicated device or element must be provided with a particular orientation, constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0048] In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0049] The present application discloses an adsorbent for chlorosilane purification, comprising a functionalized activated carbon adsorbent, an organic group functionalized mesoporous molecular sieve adsorbent, and a functional group modified multi-walled carbon nanotube adsorbent, wherein:

[0050] The functionalized activated carbon adsorbent is one or more of modified activated carbon containing imidazole group or benzyl group or ketoxime group, for removing phosphorus impurities in chlorosilane;

[0051] The organic group functionalized mesoporous molecular sieve adsorbent is one or more of chlorophenyl or gem-amino oxime or pyrrozine group modified mesoporous molecular sieves for removing boron impurities in chlorosilane;

[0052] The functional group modified multi-walled carbon nanotube adsorbent is one or more of hydrazine group or gem-dicyanide group or quinoline group modified multi-walled carbon nanotubes for removing metal impurities in chlorosilane.

[0053] Correspondingly, the application also discloses a method for purifying chlorosilane, comprising the following steps:

[0054] S1, adsorbing chlorosilane with the functionalized activated carbon adsorbent described above to remove phosphorus impurities, so as to obtain a first feed liquid;

[0055] S2, performing crude distillation purification on the first feed liquid to separate out silicon tetrachloride, so as to obtain liquid-phase crude trichlorosilane;

[0056] S3, adsorbing the liquid-phase crude trichlorosilane with the organic group functionalized mesoporous molecular sieve adsorbent described above to remove boron impurities, so as to obtain a second feed liquid;

[0057] S4, performing rectification purification on the second feed liquid to further separate out residual silicon tetrachloride, so as to obtain refined trichlorosilane;

[0058] S5, adsorbing the refined trichlorosilane with the functional group modified multi-walled carbon nanotube adsorbent described above to remove metal impurities, so as to obtain a third feed liquid;

[0059] S6, performing re-rectification purification on the third feed liquid, so as to obtain trichlorosilane products.

[0060] Correspondingly, the application also discloses a system for purifying chlorosilane, which is used for the method for purifying chlorosilane described above, and comprises a first adsorption device, a crude distillation device, a second adsorption device, a rectification device, a third adsorption device and a re-rectification device, wherein:

[0061] The first adsorption device is filled with the functionalized activated carbon adsorbent described above, and is used for removing phosphorus impurities in chlorosilane to obtain a first feed liquid;

[0062] The crude distillation device is connected with the first adsorption device, and is used for receiving the first feed liquid and performing crude distillation purification thereon to separate out silicon tetrachloride, so as to obtain liquid-phase crude trichlorosilane;

[0063] The second adsorption device is connected with the crude distillation device, and the second adsorption device is filled with the organic group functionalized mesoporous molecular sieve adsorbent described above, and is used for receiving the liquid-phase crude trichlorosilane and removing boron impurities to obtain a second feed liquid;

[0064] The rectification device is connected with the second adsorption device and used for receiving the second feed liquid and rectifying and purifying the same to separate residual silicon tetrachloride and obtain refined trichlorosilane;

[0065] The third adsorption device is connected with the rectification device and filled with the functional group modified multi-walled carbon nanotube adsorbent as described above, and used for receiving the refined trichlorosilane and removing metal impurities to obtain a third feed liquid;

[0066] The re-rectification device is connected with the third adsorption device and used for receiving the third feed liquid and re-rectifying and purifying the same to further separate residual silicon tetrachloride and obtain a high-purity trichlorosilane product.

[0067] Embodiment 1

[0068] As shown in Figure 1 The embodiment discloses an adsorbent for chlorosilane purification, which includes a functionalized activated carbon adsorbent, an organic group functionalized mesoporous molecular sieve adsorbent and a functional group modified multi-walled carbon nanotube adsorbent, wherein:

[0069] The functionalized activated carbon adsorbent is one or more of modified activated carbons containing imidazole groups or benzyl groups or ketoxime groups, and the adsorbent has high selectivity and adsorbability for phosphorus impurities, especially for high-boiling phosphorus impurities, and can effectively remove phosphorus impurities in chlorosilane;

[0070] The organic group functionalized mesoporous molecular sieve adsorbent is one or more of modified mesoporous molecular sieves containing chlorophenyl groups or geminal amino oxime groups or pyrrozine groups, and the adsorbent is integrated by inorganic material mesoporous molecular sieves and organic functional groups through covalent bonds. Since a large number of surface silicon hydroxyl groups exist on the pore walls of the mesoporous molecular sieves, chlorophenyl groups, geminal amino oxime groups, pyrrozine groups and the like can be introduced into the pore walls (surfaces and interiors) of the mesoporous molecular sieves, the selectivity and adsorbability of the adsorbent for boron impurities are increased, and the boron impurities in chlorosilane can be effectively removed. In addition, the number of organic functional groups introduced into the adsorbent can be controlled by adjusting the number of silicon hydroxyl groups, so as to increase the saturated adsorption capacity of the adsorbent. Furthermore, the pore size and pore structure of the adsorbent can be regulated by adjusting the pore size and pore structure of the mesoporous molecular sieves, so as to increase the specific surface area and pore volume of the adsorbent, thereby improving the adsorption capacity of the adsorbent;

[0071] The functional group modified multi-walled carbon nanotube adsorbent is one or more of modified multi-walled carbon nanotubes containing hydrazine groups or gem-dicyan groups or quinoline groups, which introduces hydrazine groups, gem-dicyan groups, quinoline groups and the like functional groups on the surface and inside the pores of the multi-walled carbon nanotubes, can increase the affinity of the multi-walled carbon nanotubes to metal impurities in chlorosilane, has strong selectivity and adsorption to metal impurities, thereby effectively removing iron, copper, chromium, nickel, zinc, sodium and other metal impurities in chlorosilane, and the adsorbent has a large specific surface area and a large saturated adsorption capacity, so that the adsorbent has a longer service life.

[0072] Specifically, the preparation steps of the functionalized activated carbon adsorbent are as follows (taking the preparation of modified activated carbon containing imidazole groups as an example):

[0073] 18-22 g of activated carbon is dispersed in 190-210 mL of ethanol, 8.75-11.68 g of 4-(imidazol-1-yl) benzaldehyde is dissolved in 20-23 mL of ethanol; then the two solutions are mixed, 1.14-2.11 g of polyvinylpyrrolidone-K30 (PVP-K30) is added as a dispersant and 5-7 mL of formic acid is added as a catalyst, and then the mixture is stirred at 25°C at a stirring speed of 200 r / min for 18-20 h; after stirring, the product is washed with ethanol for several times, preferably 5 times, and then freeze-dried for 34-36 h to obtain the imidazole group modified functionalized activated carbon.

[0074] It should be noted that when preparing modified activated carbon containing benzyl or ketoxime groups, the above 4-(imidazol-1-yl) benzaldehyde is replaced by the corresponding 4-benzyl benzaldehyde or diacetyl monoxime, and the other steps are not repeated here.

[0075] Specifically, the preparation steps of the organic group functionalized mesoporous molecular sieve adsorbent are as follows (taking the preparation of modified mesoporous molecular sieve containing chlorophenyl groups as an example):

[0076] 2.5-4.0 g of P123 is dissolved in 50-65 mL of 1.5 mol / L HCl solution, and 0.45-0.62 g of cetyltrimethylammonium bromide (CTAB) is dissolved in 20-30 mL of deionized water; then, the two solutions are mixed uniformly and 15-22 mL of anhydrous ethanol is added; then, the above mixture is stirred at 35°C for 45-60 min, and 8-10 mL of tetraethyl orthosilicate (TEOS) is added dropwise during the process; then, heating to 75°C for reaction, and the reaction time is controlled for 8-10 h; after the reaction is completed, the product is filtered and washed, and then calcined at 550°C for 6-8 h to obtain the mesoporous molecular sieve;

[0077] The 10.8-12.3 g of the mesoporous molecular sieve prepared above and 3.55-5.18 g of ethyl 4-chlorophenylacetate are dispersed in 245-260 mL of ethanol, 0.4-0.6 g of the dispersant polyvinyl alcohol is dissolved in 110-130 mL of ultrapure water; the two solutions are then mixed thoroughly, 1.18-2.11 g of the initiator 2,2-azobisisobutyronitrile (AIBN) is then added, and the mixture is stirred vigorously at 50 °C for 7-9 h; after the stirring is completed, the product is washed with deionized water for several times, preferably 3-5 times, and then dried at 60 °C overnight to obtain the mesoporous molecular sieve modified with chlorophenyl groups.

[0078] It should be noted that when the modified mesoporous molecular sieve containing an amidoxime group or a quinolizine group is prepared, the above-mentioned ethyl 4-chlorophenylacetate is replaced by the corresponding 4-pyridyl amidoxime or 7,8-dimethyl quinolizine, and the other steps are not described here one by one.

[0079] Specifically, the preparation steps of the functional group modified multi-walled carbon nanotube adsorbent are as follows (taking the preparation of the modified multi-walled carbon nanotube containing a hydrazine group as an example):

[0080] The 5.8-7.2 g of multi-walled carbon nanotubes, 1.1-2.3 g of tert-butyl hydrazine formate, and 0.15-0.28 g of the dispersant polyvinyl alcohol are dispersed in 150-170 mL of ethanol, 10-13 mL of 2 wt% glutaraldehyde aqueous solution is then added dropwise as a crosslinking agent, and the mixture is stirred at 60 °C at a stirring speed of 300 r / min for 10-12 h; after the stirring is completed, the product is washed with ethanol for several times, preferably 5 times, and then dried at 60 °C for 22-24 h to obtain the multi-walled carbon nanotube modified with a hydrazine group.

[0081] It should be noted that when the modified multi-walled carbon nanotube containing a dicyanide group or a quinoline group is prepared, the above-mentioned tert-butyl hydrazine formate is replaced by the corresponding dicyanamide or 2-(quinolin-2-yl)quinazoline-4-amine, and the other steps are not described here one by one.

[0082] In some embodiments, the functional group content of the functionalized activated carbon adsorbent is 3-7 mmol / g, the specific surface area is 460-1390 m 2 / g, and the pore size is 5-73 nm.

[0083] In some embodiments, the organic group content of the organic group functionalized mesoporous molecular sieve adsorbent is 1-5 mmol / g, the specific surface area is 750-1500 m 2 / g, and the pore size is 2-50 nm.

[0084] In some embodiments, the functional group modified multi-walled carbon nanotube adsorbent has an organic group content of 2-5 mmol / g, a specific surface area of 280-1270 m 2 / g, and a pore size of 2-20 nm.

[0085] The adsorbent for chlorosilane purification in the embodiment has a large specific surface area and strong selectivity, can effectively remove phosphorus impurities, boron impurities and metal impurities in chlorosilane, improve the purity of chlorosilane, and obtain high-purity trichlorosilane product. Compared with the traditional technology, the problems such as inability to effectively control the cleanliness of the resin adsorbent, high cost, and risk of thermal decomposition can be avoided.

[0086] Embodiment 2

[0087] The embodiment discloses a method for chlorosilane purification, comprising:

[0088] S1, adsorbing the chlorosilane to be purified with the functionalized activated carbon adsorbent described in embodiment 1 to remove phosphorus impurities, to obtain a first feed liquid;

[0089] S2, performing crude distillation purification on the first feed liquid to separate out silicon tetrachloride and obtain liquid-phase crude trichlorosilane;

[0090] S3, adsorbing the liquid-phase crude trichlorosilane with the organic group functionalized mesoporous molecular sieve adsorbent described in embodiment 1 to remove boron impurities, to obtain a second feed liquid;

[0091] S4, performing rectification purification on the second feed liquid to separate out residual silicon tetrachloride and obtain refined trichlorosilane;

[0092] S5, adsorbing the refined trichlorosilane with the functional group modified multi-walled carbon nanotube adsorbent described in embodiment 1 to remove metal impurities such as iron, copper, chromium, nickel, zinc and sodium, to obtain a third feed liquid;

[0093] S6, performing rectification purification again on the third feed liquid to further separate out residual silicon tetrachloride and obtain high-purity trichlorosilane product.

[0094] Specifically, the crude distillation purification process in step S2 is performed by using a crude distillation device coupled in sequence for multi-stage purification, and the crude distillation purification process has a temperature of 56-107℃ and a pressure of 0.2-0.7 MPa. In the embodiment, the crude distillation device is coupled in sequence for multi-stage purification, and the crude distillation purification process has a temperature of 56-107℃ and a pressure of 0.2-0.7 MPa. Figure 1As shown, the crude distillation purification process preferably adopts three-stage crude distillation purification, wherein the temperature of the first-stage crude distillation purification is preferably 56-94°C, and the pressure is preferably 0.2-0.47 MPa; the temperature of the second-stage crude distillation purification is preferably 75-98°C, and the pressure is preferably 0.31-0.56 MPa; the temperature of the third-stage crude distillation purification is preferably 86-107°C, and the pressure is preferably 0.47-0.7 MP; and the temperature and pressure of the later-stage crude distillation purification process should be successively increased relative to the temperature and pressure of the former-stage crude distillation purification process.

[0095] The rectification purification process in step S4 adopts multi-stage purification by successively coupled rectification devices, and the temperature of the rectification purification process is 60-94°C, and the pressure is set to 0.1-0.37 MPa. In this embodiment, as shown, Figure 1 the rectification purification process preferably adopts two-stage rectification purification, wherein the temperature of the first-stage rectification purification is preferably 60-101°C, and the pressure is preferably 0.1-0.42 MPa; the temperature of the second-stage rectification purification is preferably 87-101°C, and the pressure is preferably 0.25-0.49 MPa; and the temperature and pressure of the later-stage rectification purification process are successively increased relative to the temperature and pressure of the former-stage rectification purification process.

[0096] The temperature of the re-rectification purification process in step S6 is 96-105°C, and the pressure is set to 0.4-0.6 MPa.

[0097] In some embodiments, before step S1, the method further comprises:

[0098] S0, the low-boiling phosphorus impurities in the feed liquid are converted into high-boiling phosphorus impurities (PCl5) by chlorination and phosphorylation reaction of the low-boiling phosphorus impurities with chlorine gas under the action of a catalyst, and the high-boiling phosphorus impurities are easier to remove than the low-boiling phosphorus impurities, thereby improving the removal rate of phosphorus impurities.

[0099] In some embodiments, the catalyst is a supported catalyst, which is a catalyst in which an active substance is supported on a carrier for catalyzing the reaction of chlorine gas with low-boiling phosphorus impurities. In this embodiment, the catalyst is preferably one or more of NaAlCl4 / activated carbon, FeN4 / C3N4, and KAlBr4 / zeolite.

[0100] In some embodiments, the content of the active substance in the catalyst is 3%-8%, and the specific surface area of the catalyst is 550-965 m 2 / g.

[0101] The method for chlorosilane purification of this embodiment has at least the following effects:

[0102] (1) By using adsorption treatment with a functionalized activated carbon adsorbent containing imidazole or benzyl or ketoxime groups, phosphorus impurities in chlorosilanes can be efficiently removed;

[0103] (2) By using adsorption treatment with a mesoporous molecular sieve adsorbent functionalized with organic groups containing chlorophenyl or gem-amino oxime or pyrrolizine groups, boron impurities in chlorosilanes can be efficiently removed;

[0104] (3) By using adsorption treatment with multi-walled carbon nanotubes modified with functional groups containing hydrazine or gem-dicyan groups or quinoline groups, metal impurities such as iron, copper, chromium, nickel, zinc, sodium, etc. in chlorosilanes can be efficiently removed;

[0105] (4) The method combines rectification technology with adsorption technology, and through the synergistic effect of rectification technology and adsorption technology, not only can phosphorus, boron, silicon tetrachloride, and metal impurities that can affect the quality of polysilicon products be effectively removed, but also the purity of chlorosilanes can be improved. The polysilicon produced from trichlorosilane purified by the method can effectively improve the quality of polysilicon, and at the same time, the energy consumption of the crude distillation and rectification process can be reduced, achieving the purpose of reducing costs and increasing efficiency;

[0106] (5) By treating chlorosilanes at low temperature, low-boiling phosphorus impurities in chlorosilanes can be converted into high-boiling phosphorus impurities, which not only can further improve the removal rate of phosphorus impurities, but also can reduce the energy consumption of the subsequent crude distillation and rectification process;

[0107] (6) The method does not require pretreatment of the purified chlorosilane material, thereby simplifying the process and reducing production costs;

[0108] (7) Compared with traditional technologies, the method can avoid the problems of the resin adsorbent such as uncontrollable cleanliness, high cost, and risk of thermal decomposition, and is safe and stable.

[0109] Example 3

[0110] As shown in Figure 1 , the present embodiment discloses a system for purifying chlorosilanes, which is used for the method for purifying chlorosilanes described in Example 1, and comprises a first adsorption device 2, a crude distillation device, a second adsorption device 6, a rectification device, a third adsorption device 9, and a re-rectification device 10, wherein:

[0111] The first adsorption device 2 is filled with the functionalized activated carbon adsorbent described in Example 1, and is used for introducing chlorosilanes to be purified and removing phosphorus impurities therein to obtain a first liquid;

[0112] The crude distillation device is connected with the first adsorption device 2, and is used for receiving the first liquid and performing crude distillation purification thereon to separate silicon tetrachloride and obtain liquid-phase crude trichlorosilane;

[0113] The second adsorption device 6 is connected with the crude distillation device, and is filled with the organic group functionalized mesoporous molecular sieve adsorbent described in the embodiment 1, and is used for receiving the liquid phase crude trichlorosilane and removing boron impurities to obtain a second feed liquid;

[0114] The rectification device is connected with the second adsorption device 6, and is used for receiving the second feed liquid and rectifying and purifying the same to separate residual silicon tetrachloride and obtain refined trichlorosilane;

[0115] The third adsorption device 9 is connected with the rectification device, and is filled with the functional group modified multi-walled carbon nanotube adsorbent described in the embodiment 1, and is used for receiving the refined trichlorosilane and removing metal impurities such as iron, copper, chromium, nickel, zinc and sodium to obtain a third feed liquid;

[0116] The re-rectification device 10 is connected with the third adsorption device 9, and is used for receiving the third feed liquid and re-rectifying and purifying the same to further separate residual silicon tetrachloride and obtain high-purity trichlorosilane product.

[0117] Specifically, the first adsorption device 9 is an adsorption column filled with the above-mentioned functionalized activated carbon adsorbent, which has one or more of imidazole group, benzyl group and ketoxime group, has high selectivity and adsorbability to phosphorus impurities, especially high-boiling phosphorus impurities, and can effectively remove phosphorus impurities in chlorosilane.

[0118] The crude distillation device includes a plurality of crude distillation columns coupled in sequence to perform multi-stage crude distillation purification. Preferably, as shown in Figure 1 The crude distillation device is a three-stage crude distillation device, including a crude distillation first-stage column 3, a crude distillation second-stage column 4 and a crude distillation third-stage column 5 arranged in series, the first feed liquid enters the crude distillation first-stage column 3, is heated by the column bottom and is condensed by the column top gas phase reflux, and is subjected to mass transfer and heat transfer of gas and liquid phases by means of multiple partial vaporization and partial condensation, so that the trichlorosilane is vaporized and discharged from the top of the previous crude distillation column and then enters the next crude distillation column after condensation, while the silicon tetrachloride is intercepted in the column bottom of each crude distillation column and then discharged, thereby separating the trichlorosilane from the silicon tetrachloride to obtain the liquid phase crude trichlorosilane. In this embodiment, each crude distillation column is preferably a packed column.

[0119] The second adsorption device 6 is a plurality of (such as two) sets of adsorption columns arranged in parallel, and the adsorption columns are filled with the above-mentioned organic group functionalized mesoporous molecular sieve adsorbent, which has one or more of chlorobenzene group, geminal amino oxime group and pyrrozine group, can increase the selectivity and adsorbability to boron impurities, and thus more effectively removes the boron impurities in chlorosilane.

[0120] The rectification device comprises several rectification towers coupled in sequence to perform multi-stage rectification purification. Preferably, as shown in Figure 1 The rectification device is a two-stage rectification device, comprising a first-stage rectification tower 7 and a second-stage rectification tower 8 arranged in series. The second feed liquid is fed into the first-stage rectification tower, and is heated by the tower bottom and condensed by the tower top gas phase reflux. Through multiple partial vaporization and partial condensation, mass transfer and heat transfer of the gas and liquid phases are performed, so that the trichlorosilane in the second feed liquid is vaporized and discharged from the top of the first-stage rectification tower, and then enters the second-stage rectification tower after condensation. The residual silicon tetrachloride in the second feed liquid is intercepted in the tower bottom of each rectification tower, and then discharged, so as to separate the residual silicon tetrachloride in the second feed liquid and obtain purified trichlorosilane. In this embodiment, each rectification tower is preferably a packed tower.

[0121] The third adsorption device 9 is a plurality of (such as two) adsorption columns arranged in series, and the adsorption columns are filled with the functional group modified multi-walled carbon nanotube adsorbent described above. The adsorbent has one or more functional groups of hydrazine group, gem-dicyan group and quinoline group introduced, which can increase the affinity of the adsorbent to metal impurities in chlorosilane, and has strong selectivity and adsorbability to metal impurities such as iron, copper, chromium, nickel, zinc and sodium, so as to effectively remove the metal impurities in chlorosilane.

[0122] The re-rectification device 10 is a packed tower.

[0123] In some embodiments, a regeneration heating jacket is arranged outside each adsorption device to heat and desorb the adsorbent filled in the adsorption column. The volume of the adsorption column is preferably 5m 3 .

[0124] In some embodiments, the system further comprises a low-temperature chlorination device 1 connected with the first adsorption device 2. The bottom of the low-temperature chlorination device 1 is provided with a chlorosilane feeding port for feeding the chlorosilane to be purified, and the top of the low-temperature chlorination device 1 is provided with a chlorine gas inlet. A catalyst is arranged in the low-temperature chlorination device 1. The low-temperature chlorination device 1 is used for low-temperature chlorination treatment of the chlorosilane to be purified, so that the low-boiling-point phosphorus impurities in the chlorosilane are converted into high-boiling-point phosphorus impurities through chlorination and phosphorylation reactions under the action of the catalyst. Then, the chlorosilane after the low-temperature chlorination treatment is fed into the first adsorption device 2. Compared with the low-boiling-point phosphorus impurities, the high-boiling-point phosphorus impurities are easier to remove, so that the removal rate of the phosphorus impurities can be improved.

[0125] In some embodiments, the catalyst is a supported catalyst, which is a catalyst in which an active substance is supported on a carrier to catalyze the reaction of chlorine gas and low-boiling-point phosphorus impurities. In this embodiment, the catalyst is preferably one or more of NaAlCl4 / activated carbon, FeN4 / C3N4 and KAlBr4 / zeolite.

[0126] In some embodiments, the active substance content in the catalyst is 3% to 8%, and the specific surface area of the catalyst is 550 to 965 m 2 / g.

[0127] Example 4

[0128] The present example discloses a method for chlorosilane purification, which is accomplished by using the system for chlorosilane purification described in Example 3, wherein the chlorosilane to be purified is from a liquid-phase crude chlorosilane of cold hydrogenation, and the composition of the liquid-phase crude chlorosilane is: 96.5% of trichlorosilane, 2.0% of dichlorodisilane, 1.5% of silicon tetrachloride, 300 ppb of total metal impurities, 50 ppb of boron non-metallic impurities, and 60 ppb of phosphorus non-metallic impurities.

[0129] As shown in Figure 1 , the steps of the method of the present example include:

[0130] S0, adding NaAlCl4 / activated carbon with an active substance content of 4% and a specific surface area of 697 m 2 / g into a low-temperature chlorination device 1, feeding the above-mentioned liquid-phase crude chlorosilane from the bottom of the low-temperature chlorination device 1, feeding chlorine gas from the top of the low-temperature chlorination device 1, and controlling the temperature in the low-temperature chlorination device 1 to be 0℃, and treating the crude chlorosilane in the low-temperature chlorination device 1, so that the low-boiling phosphorus impurities in the chlorosilane are chlorinated and phosphorylated under the catalysis of NaAlCl4 / activated carbon, and the low-boiling phosphorus impurities are converted into high-boiling phosphorus impurities;

[0131] S1, feeding the chlorosilane treated in the low-temperature chlorination device 1 into a first adsorption device 2, and performing adsorption treatment on the chlorosilane by using modified activated carbon containing imidazole groups with an imidazole group content of 3.9 mmol / g, a specific surface area of 590 m 2 / g, and a pore size of 15-17 nm, so as to remove the phosphorus impurities in the chlorosilane, and obtain a first feed liquid;

[0132] S2, the first feed liquid is introduced into the first-stage crude distillation column 3 for first-stage crude distillation purification, the temperature of the first-stage crude distillation column 3 is controlled to be 56℃, and the pressure is controlled to be 0.2MPa, so that light components such as trichlorosilane are vaporized and discharged from the top of the first-stage crude distillation column 3, and after condensation, a first-stage crude distillation liquid is obtained, and heavy components such as silicon tetrachloride are trapped in the bottom of the first-stage crude distillation column 3; the first-stage crude distillation liquid is introduced into the second-stage crude distillation column 4 for second-stage crude distillation purification, the temperature of the second-stage crude distillation column 4 is controlled to be 75℃, and the pressure is controlled to be 0.31MPa, so that light components such as trichlorosilane in the first-stage crude distillation liquid are vaporized and discharged from the top of the second-stage crude distillation column 4, and after condensation, a second-stage crude distillation liquid is obtained, and heavy components such as silicon tetrachloride remaining in the first-stage crude distillation liquid are trapped in the bottom of the second-stage crude distillation column 4; the second-stage crude distillation liquid is introduced into the third-stage crude distillation column 5 for third-stage crude distillation purification, the temperature of the third-stage crude distillation column 5 is controlled to be 86℃, and the pressure is controlled to be 0.47MPa, so that light components such as trichlorosilane in the second-stage crude distillation liquid are vaporized and discharged from the top of the third-stage crude distillation column 5, and after condensation, the liquid-phase crude trichlorosilane is obtained, and heavy components such as silicon tetrachloride remaining in the second-stage crude distillation liquid are trapped in the bottom of the third-stage crude distillation column 5;

[0133] S3, the liquid-phase trichlorosilane is introduced into the second adsorption device 6 composed of two sets of adsorption columns a1 and a2 connected in parallel, and is subjected to adsorption treatment by using modified mesoporous molecular sieves containing chlorobenzene groups with a chlorobenzene group content of 2mmol / g, a specific surface area of 1050m 2 / g, and a pore size of 18-22nm, so as to remove boron impurities therein, and a second feed liquid is obtained, wherein the temperature in the second adsorption device is 25℃, and the adsorption pressure is 0.2MPa;

[0134] S4, the second feed liquid is introduced into the first-stage rectification column 7 for first-stage rectification purification, the temperature of the first-stage rectification column 7 is controlled to be 60℃, and the pressure is controlled to be 0.1MPa, so that light components such as trichlorosilane in the second feed liquid are vaporized and discharged from the top of the first-stage rectification column 7, and after condensation, a first-stage rectification liquid is obtained, and heavy components such as silicon tetrachloride remaining in the first feed liquid are trapped in the bottom of the first-stage rectification column 7; the first-stage rectification liquid is introduced into the second-stage rectification column 8 for second-stage rectification purification, the temperature of the second-stage rectification column 8 is controlled to be 87℃, and the pressure is controlled to be 0.25MPa, so that light components such as trichlorosilane in the first-stage rectification liquid are vaporized and discharged from the top of the second-stage rectification column 8, and after condensation, the refined trichlorosilane is obtained, and heavy components such as silicon tetrachloride remaining in the first-stage rectification liquid are trapped in the bottom of the second-stage rectification column 8;

[0135] S5, the refined trichlorosilane is introduced into the third adsorption device 9 composed of two sets of adsorption columns b1 and b2 connected in series, and is subjected to adsorption treatment by using hydrazine groups with a hydrazine group content of 2.5mmol / g, a specific surface area of 590m 2 / g, and the modified multi-walled carbon nanotubes containing hydrazine groups with a pore size of 6-9 nm are used for adsorption treatment, so that the hydrazine groups on the surface and inside the pores of the adsorbent are complexed with metal ions in the refined trichlorosilane, thereby removing metal impurities such as iron, chromium, nickel, copper, zinc, and sodium in the trichlorosilane, to obtain a third liquid, wherein the temperature in the third adsorption device is 23°C, and the adsorption pressure is 0.29 MPa;

[0136] S6, the third liquid is introduced into the rectification device 10 for rectification and purification, wherein the temperature of the rectification tower 10 is controlled at 98°C, and the pressure is controlled at 0.42 MPa, so that the trichlorosilane in the third liquid is vaporized and discharged from the top of the rectification device 10, and after condensation, high-purity trichlorosilane products are obtained, and the residual silicon tetrachloride and other heavy components in the third liquid are intercepted in the tower kettle of the rectification device.

[0137] Samples are taken from the inlet of the first adsorption device 2 and the outlet of the third adsorption device 9, and the contents of impurities such as phosphorus, boron, iron, chromium, nickel, and copper are detected, and the detection results are shown in Table 1.

[0138] As can be seen from Table 1, after the treatment by the method of the present embodiment, the contents of non-metallic impurities such as phosphorus and boron and metallic impurities such as iron, chromium, nickel, and copper are greatly reduced, which shows that the method of the present embodiment can effectively remove phosphorus impurities, boron impurities, and metallic impurities in chlorosilane.

[0139] Table 1: Impurity detection results

[0140]

[0141] Example 5

[0142] The present embodiment discloses a method for purifying chlorosilane, which is completed by using the system for purifying chlorosilane described in Example 3, and compared with Example 4, the steps are basically the same, and the difference lies in that:

[0143] The composition of the liquid-phase crude chlorosilane to be purified in the present embodiment 5 is: trichlorosilane 95.5%, dichlorodihydrogen silane 3%, and silicon tetrachloride 1.5%;

[0144] In step S0, the catalyst used for low-temperature chlorination treatment is FeN4 / C3N4, wherein the content of active substance is 6.5%, and the specific surface area is 802 m 2 / g;

[0145] In step S1, the modified activated carbon containing benzyl groups is used for adsorption treatment in the first adsorption device 2, wherein the content of benzyl groups is 5 mmol / g, the specific surface area is 880 m 2 / g, and the pore size is 30-33 nm;

[0146] In step S2, the temperature of the crude distillation first-stage column 3 is 75℃, the pressure is 0.31MPa; the temperature of the crude distillation second-stage column 4 is 81℃, the pressure is 0.35MPa; the temperature of the crude distillation third-stage column 5 is 94℃, the pressure is 0.53MPa;

[0147] In step S3, the second adsorption device 6 uses a modified mesoporous molecular sieve containing geminal amidoxime groups for adsorption treatment, wherein the content of geminal amidoxime groups is 3.5mmol / g, the specific surface area is 1380m 2 / g, and the pore size is 34-37nm;

[0148] In step S4, the temperature of the rectification first-stage column 7 is 87℃, the pressure is 0.25MPa; the temperature of the rectification second-stage column 8 is 90℃, the pressure is 0.31MPa;

[0149] In step S5, the third adsorption device 9 uses a modified multi-walled carbon nanotube containing geminal dinitrile groups for adsorption treatment, wherein the content of geminal dinitrile groups is 3.6mmol / g, the specific surface area is 863m 2 / g, and the pore size is 9-13nm;

[0150] In step S5, the temperature of the re-distillation device 10 is 92℃, the pressure is 0.35MPa.

[0151] Samples are taken from the inlet of the first adsorption device 2 and the outlet of the third adsorption device 9, and the contents of phosphorus, boron, iron, chromium, nickel, copper and other impurities therein are detected, and the detection results are shown in Table 2.

[0152] Table 2 Impurity detection results

[0153]

[0154] As shown in Table 2, after the method of the present embodiment is used for treatment, the contents of non-metallic impurities such as phosphorus and boron and metallic impurities such as iron, chromium, nickel and copper are greatly reduced, thus indicating that the method of the present embodiment can effectively remove phosphorus impurities, boron impurities and metallic impurities in chlorosilane.

[0155] Example 6

[0156] The present embodiment discloses a method for purifying chlorosilane, which uses the system for purifying chlorosilane described in Example 3, and the steps are basically the same compared with Example 4, and the difference lies in that:

[0157] In the present embodiment 6, the composition of the liquid-phase crude chlorosilane to be purified is: trichlorosilane 96.5%, dichlorosilane 2%, and silicon tetrachloride 1.5%;

[0158] In step S0, the catalyst used in the low-temperature chlorination treatment is KAlBr4 / zeolite, wherein the content of the active substance is 8%, the specific surface area is 955 m 2 / g;

[0159] In step S1, the adsorption treatment in the first adsorption device 2 is performed using a modified activated carbon containing ketoxime groups, wherein the content of the ketoxime groups is 6.8 mmol / g, the specific surface area is 1260 m 2 / g, and the pore size is 69-72 nm;

[0160] In step S2, the temperature of the crude distillation first-stage column 3 is 94°C, the pressure is 0.47 MPa; the temperature of the crude distillation second-stage column 4 is 98°C, the pressure is 0.56 MPa; the temperature of the crude distillation third-stage column 5 is 107°C, the pressure is 0.69 MPa;

[0161] In step S3, the adsorption treatment in the second adsorption device 6 is performed using a modified mesoporous molecular sieve containing pyrazine groups, wherein the content of the pyrazine groups is 4.7 mmol / g, the specific surface area is 1476 m 2 / g, and the pore size is 39-43 nm;

[0162] In step S4, the temperature of the rectification first-stage column 7 is 98°C, the pressure is 0.42 MPa; the temperature of the rectification second-stage column 8 is 101°C, the pressure is 0.49 MPa;

[0163] In step S5, the adsorption treatment in the third adsorption device 9 is performed using a modified multi-walled carbon nanotube containing quinoline groups, wherein the content of the quinoline groups is 4.3 mmol / g, the specific surface area is 1173 m 2 / g, and the pore size is 14-18 nm;

[0164] In step S5, the temperature of the re-rectification device 10 is 104°C, the pressure is 0.57 MPa.

[0165] Samples are taken from the inlet of the first adsorption device 2 and the outlet of the third adsorption device 9, and the contents of phosphorus, boron, iron, chromium, nickel, copper and other impurities are detected, and the detection results are shown in Table 3.

[0166] As can be seen from Table 3, after the treatment by the method of the present embodiment, the contents of non-metallic impurities such as phosphorus and boron, and metallic impurities such as iron, chromium, nickel and copper are greatly reduced, which shows that the method of the present embodiment can effectively remove phosphorus impurities, boron impurities and metallic impurities in chlorosilane.

[0167] Table 3: Impurity detection results

[0168]

[0169] Comparative Example 1

[0170] The present comparative example discloses a method for chlorosilane purification, which is completed by using the system for chlorosilane purification described in Example 3, and the steps are basically the same compared with Example 4, and the difference is that:

[0171] The composition of the liquid-phase crude chlorosilane to be purified in the present comparative example is: 94% of trichlorosilane, 3.5% of dichlorodisilane, and 2.5% of silicon tetrachloride;

[0172] The catalyst used in the low-temperature chlorination treatment is aluminum trichloride;

[0173] The temperature of the crude distillation first-stage column 3 is 55°C, and the pressure is 0.19 MPa; the temperature of the crude distillation second-stage column 4 is 60°C, and the pressure is 0.3 MPa; the temperature of the crude distillation third-stage column 5 is 67°C, and the pressure is 0.37 MPa;

[0174] The mesoporous molecular sieve with a specific surface area of 1260 m 2 / g and a pore size of 19-25 nm is used in the second adsorption device 6 for adsorption treatment;

[0175] The temperature of the rectification first-stage column 7 is 61°C, and the pressure is 0.12 MPa; the temperature of the rectification second-stage column 8 is 65°C, and the pressure is 0.15 MPa;

[0176] The multi-walled carbon nanotube with a specific surface area of 360 m 2 / g and a pore size of 7-11 nm is used in the third adsorption device 9 for adsorption treatment;

[0177] The temperature of the re-rectification device 10 is 70°C, and the pressure is 0.18 MP.

[0178] The samples are taken from the inlet of the first adsorption device 2 and the outlet of the third adsorption device 9, and the contents of impurities such as phosphorus, boron, iron, chromium, nickel, and copper are detected, and the detection results are shown in Table 4.

[0179] As can be seen from Table 4, after the treatment by the method of the present comparative example, the contents of non-metallic impurities such as phosphorus and boron and metallic impurities such as iron, chromium, nickel, and copper are reduced to a certain extent, i.e., the contents of non-metallic impurities such as phosphorus and boron and metallic impurities such as iron, chromium, nickel, and copper in chlorosilane can be removed to a certain extent, but compared with Example 4, the removal rate of the above-mentioned impurities in the present comparative example 1 is obviously lower than that in Example 4, and thus it can be seen that by using the adsorbent modified by containing specific groups such as imidazole groups as described in the present application, the removal rates of phosphorus impurities, boron impurities, and metallic impurities in chlorosilane can be obviously improved.

[0180] Table 4: Impurity detection results

[0181]

[0182] It is understood that the above embodiments are only exemplary for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the present application, and these modifications and improvements are also considered to be within the scope of the present application.

Claims

1. A method for purifying chlorosilanes, characterized in that, include: S1, chlorosilanes are adsorbed using a functionalized activated carbon adsorbent to remove phosphorus impurities, yielding a first feed solution; wherein, the functionalized activated carbon adsorbent is one or more modified activated carbons containing imidazole, benzyl, or ketoxime groups, the functional group content of the functionalized activated carbon adsorbent is 3~7 mmol / g, and the specific surface area is 460~1390 m². 2 / g, with a pore size of 5~73nm; S2, the first liquid is purified by crude distillation to separate dichlorosilane and silicon tetrachloride, and obtain liquid crude trichlorosilane; S3, the crude trichlorosilane in liquid phase is adsorbed using an organically functionalized mesoporous molecular sieve adsorbent to remove boron impurities, yielding a second feed solution; wherein, the organically functionalized mesoporous molecular sieve adsorbent is one or more functionalized mesoporous molecular sieves containing chlorophenyl, ammoniacal oxime, or pyrazine groups, and the organic group content of the organically functionalized mesoporous molecular sieve adsorbent is 1~5 mmol / g, with a specific surface area of ​​750~1500 m². 2 / g, with a pore size of 2~50nm; S4, the second liquid is purified by distillation to further separate dichlorosilane and silicon tetrachloride to obtain refined trichlorosilane; S5, the refined trichlorosilane is adsorbed using a functional group-modified multi-walled carbon nanotube adsorbent to remove metal impurities, yielding a third feed solution; wherein the functional group-modified multi-walled carbon nanotube adsorbent is one or more of modified multi-walled carbon nanotubes containing hydrazine, bis(nitrile), or quinoline groups, and the organic group content of the functional group-modified multi-walled carbon nanotube adsorbent is 2~5 mmol / g, with a specific surface area of ​​280~1270 m². 2 / g, with a pore size of 2~20nm; S6. The third feed liquid is further purified by distillation to obtain trichlorosilane product.

2. The method for purifying chlorosilanes according to claim 1, characterized in that, The temperature of the crude distillation purification process in step S2 is 56~107℃ and the pressure is 0.2~0.7MPa.

3. The method for purifying chlorosilanes according to claim 1, characterized in that, In step S4, the temperature of the distillation purification process is 60~101℃, and the pressure is set to 0.1~0.49MPa.

4. The method for purifying chlorosilanes according to claim 1, characterized in that, In step S6, the temperature for the re-distillation and purification process is 96~105℃, and the pressure is set to 0.4~0.6MPa.

5. The method for purifying chlorosilanes according to any one of claims 1-4, characterized in that, Before step S1, the following is also included: Low-temperature chlorination of chlorosilanes causes low-boiling-point phosphorus impurities in the feed solution to undergo a phosphorylation reaction with chlorine gas under the action of a catalyst, converting the low-boiling-point phosphorus impurities into high-boiling-point phosphorus impurities.

6. The method for purifying chlorosilanes according to claim 5, characterized in that, The catalyst is one or more of NaAlCl4 / activated carbon, FeN4 / C3N4, and KAlBr4 / zeolite.

7. The method for purifying chlorosilanes according to claim 6, characterized in that, The catalyst contains 3% to 8% active material and has a specific surface area of ​​550 to 965 m². 2 / g.

8. A system for purifying chlorosilanes, used in the method for purifying chlorosilanes according to any one of claims 1-7, characterized in that, It includes a first adsorption unit (2), a crude distillation unit, a second adsorption unit (6), a rectification unit, a third adsorption unit (9), and a re-rectification unit (10). The first adsorption device is filled with functionalized activated carbon adsorbent to remove phosphorus impurities from chlorosilanes, yielding a first feed solution; wherein the functionalized activated carbon adsorbent is one or more of modified activated carbon containing imidazole, benzyl, or ketoxime groups, the functional group content of the functionalized activated carbon adsorbent is 3~7 mmol / g, and the specific surface area is 460~1390 m². 2 / g, with a pore size of 5~73nm; The crude distillation device is connected to the first adsorption device and is used to receive the first feed liquid and purify it by crude distillation to obtain liquid-phase crude trichlorosilane. The second adsorption device, connected to the crude distillation device, is filled with an organically functionalized mesoporous molecular sieve adsorbent. It receives the liquid-phase crude trichlorosilane and removes boron impurities to obtain a second feed solution. The organically functionalized mesoporous molecular sieve adsorbent is one or more functionalized mesoporous molecular sieves containing chlorophenyl, ammoniacal oxime, or pyrazine groups. The organic group content of the organically functionalized mesoporous molecular sieve adsorbent is 1-5 mmol / g, and its specific surface area is 750-1500 m². 2 / g, with a pore size of 2~50nm; The distillation apparatus is connected to the second adsorption apparatus and is used to receive the second feed liquid and to distill and purify it to obtain refined trichlorosilane. The third adsorption device is connected to the distillation device. The third adsorption device is filled with a functionally modified multi-walled carbon nanotube adsorbent, used to receive the refined trichlorosilane and remove metallic impurities to obtain a third feed solution. The functionally modified multi-walled carbon nanotube adsorbent is one or more modified multi-walled carbon nanotubes containing hydrazine, bis(nitrile), or quinoline groups. The organic group content of the functionally modified multi-walled carbon nanotube adsorbent is 2-5 mmol / g, and the specific surface area is 280-1270 m². 2 / g, with a pore size of 2~20nm; The re-distillation unit is connected to the third adsorption unit and is used to receive the third feed liquid and perform re-distillation purification to obtain trichlorosilane product.

9. The system for purifying chlorosilanes according to claim 8, characterized in that, It also includes a low-temperature chlorination device (1). The low-temperature chlorination device is connected to the first adsorption device and is used to perform low-temperature chlorination treatment on chlorosilanes, so that the low-boiling-point phosphorus impurities in the feed solution undergo a phosphorylation reaction with chlorine gas under the action of a catalyst, converting the low-boiling-point phosphorus impurities into high-boiling-point phosphorus impurities. After that, the treated feed solution is passed into the first adsorption device.

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