Adsorbent for adsorbing phosphorus impurities in trichlorosilane as well as preparation method and application of adsorbent

Abstract

The invention belongs to the technical field of trichlorosilane purification, and discloses an adsorbent for adsorbing phosphorus impurities in trichlorosilane and a preparation method and application thereof.The preparation method comprises the steps that activated carbon is immersed in a solution containing ammonium metavanadate and oxalic acid, ultrasonic treatment and drying are conducted, and a vanadium oxide / carbon material mixture is obtained; calcining the vanadium oxide / carbon material mixture, and performing reduction treatment to obtain the oxygen vacancy-rich activated carbon loaded vanadium oxide adsorbent. The activated carbon loaded vanadium oxide adsorbent rich in oxygen vacancies is prepared by using a dipping-calcining-reducing method, and phosphorus impurities are adsorbed and removed by using the interaction of the activated carbon loaded vanadium oxide adsorbent and PCl3. The active carbon loaded vanadium oxide adsorbent rich in oxygen vacancies interacts with PCl3, so that trace PCl3 can be efficiently removed.

Description

Technical Field

[0001] The invention belongs to the technical field of trichlorosilane purification, and particularly relates to an adsorbent for adsorbing phosphorus impurities in trichlorosilane, a preparation method and application thereof. Background Art

[0002] The rapid growth of the photovoltaic industry has driven demand in the upstream polysilicon market. In the modified Siemens process, the mainstream polysilicon production process, metallic impurities are primarily effectively removed through physical distillation. However, the removal of non-metallic impurities, particularly boron and phosphorus, remains a technical challenge due to their chemical properties being very similar to those of chlorosilanes. Further research and process improvements are required to ensure that multiple indicators of the final product meet national standards. Currently, phosphorus removal methods include extraction, partial hydrolysis, complexation, and adsorption. The latter three methods are more common. Partial hydrolysis requires strict water control, otherwise it can easily clog the equipment. Complexation is less commonly used due to its high cost and lack of reusability.

[0003] The most commonly used method at present is adsorption. The core mechanism of the adsorption method for removing trace phosphorus impurities in trichlorosilane is to separate impurities by physical or chemical adsorption between the active sites on the surface of the adsorbent and the phosphorus impurities. The specific process includes: (1) Physical adsorption: using the rich microporous structure and large specific surface area of ​​the adsorbent (such as activated carbon, molecular sieve, silica gel, etc.), phosphorus impurities are adsorbed on the surface of the adsorbent through van der Waals force. It is suitable for the removal of low-concentration impurities, but the selectivity is low and it is easily interfered by other impurities. (2) Chemical adsorption: The functional groups on the surface of the adsorbent (such as hydroxyl, carboxyl, etc.) can chemically bond with phosphorus impurities to form hydrogen bonds or covalent bonds, thereby enhancing the adsorption effect and fixing the phosphorus impurities on the surface of the adsorbent, with higher selectivity and adsorption capacity.

[0004] Patent CN200810180270.X discloses ion-exchange or chelate resin adsorbents. These resins carry groups or ions capable of exchanging or chelating boron and phosphorus ions. These groups or ions chemically react with the boron and phosphorus ions during the adsorption process to form stable complexes. Zhai et al. selected LSC-700 chelate resin, which exhibits exceptional adsorption properties for boron and phosphorus through ion exchange or chelation, separating these impurities from trichlorosilane. The abundant coordination vacancies on the resin surface enable the simultaneous adsorption of boron and phosphorus impurities through an ion exchange-chelation coupling mechanism, achieving efficient and synergistic removal of these impurities. The boron content in the treated trichlorosilane is 0.08 μg / g, and the phosphorus content is below 0.05 μg / g, meeting the stringent requirements of polysilicon manufacturers.

[0005] Almquist developed a new process for removing boron impurities from chlorosilanes using silica gel adsorption. The surface of the acid-activated silica gel contains numerous hydroxyl groups (-OH) and silicon-oxygen bonds (Si-O), which are capable of chemically adsorbing boron impurities.

[0006] U.S. Patent No. 5,723,644A proposes a new adsorbent by loading copper or copper compounds on silica. This method can effectively reduce the phosphorus impurity content to the ppb level, significantly improving the purity of chlorosilane.

[0007] Shen Feng provided a method for the removal of trace phosphorus impurities in silicon tetrachloride based on activated carbon adsorption, which reduced the phosphorus impurity content in silicon tetrachloride to the PPb level.

[0008] However, existing resin adsorbents can contain residual solvent during the synthesis process, creating the risk of residual solvent entering the chlorosilane during the adsorption process. Furthermore, the regeneration temperature cannot be too high, otherwise it will cause the resin structure and functional groups to break down. The presence of -OH on the surface of silica gel adsorbents can react with the active Si-Cl groups in the chlorosilanes, blocking the pores. Activated carbon itself has good thermal stability, but it primarily relies on physical adsorption, resulting in poor selectivity and low adsorption capacity.

[0009] Activated carbon materials not only possess a well-developed pore structure and high specific surface area, but also contain a rich array of surface functional groups. Furthermore, their mature preparation process results in significantly lower costs than other adsorbents. However, when used as an adsorbent, activated carbon's low surface chemical activity results in a weak specific adsorption capacity for impurities, with physical adsorption being the primary adsorption process. Therefore, a solution to the challenge of using natural activated carbon to remove phosphorus impurities from trichlorosilane is urgently needed. Summary of the Invention

[0010] In view of the deficiencies in the above-mentioned prior art, the present invention aims to provide an adsorbent for adsorbing phosphorus impurities in trichlorosilane, as well as a preparation method and application thereof. The activated carbon-loaded vanadium oxide adsorbent rich in oxygen vacancies adsorbs and removes phosphorus from trichlorosilane, and the removal method has good safety performance, a high removal rate for removing phosphorus impurities, and low cost.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane comprises the following steps:

[0013] The activated carbon was immersed in a solution containing ammonium metavanadate and oxalic acid, subjected to ultrasonic treatment, and dried to obtain an activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies.

[0014] Furthermore, the activated carbon was immersed in a solution containing ammonium metavanadate and oxalic acid using an equal volume impregnation method.

[0015] Furthermore, the molar ratio of ammonium metavanadate to oxalic acid is 1:2.

[0016] Furthermore, the calcination is carried out in a nitrogen atmosphere.

[0017] Furthermore, the calcination temperature is 400-600° C. and the calcination time is 4-7 hours.

[0018] Furthermore, the method further includes: reducing the activated carbon-loaded vanadium oxide adsorbent rich in oxygen vacancies.

[0019] Furthermore, the reduction treatment was carried out in a mixed atmosphere of hydrogen and argon, with the volume percentage of H2 being 10%;

[0020] The temperature of the reduction treatment is 300-600°C and the time is 2-5h.

[0021] An adsorbent for adsorbing phosphorus impurities in trichlorosilane, wherein the mass loading of vanadium in the adsorbent is 1% to 7%, and the specific surface area of ​​the adsorbent is 689.47m 2 / g-904.0m 2 / g, porosity is 0.37cm 3 / g-0.58cm 3 / g.

[0022] The invention discloses an adsorbent for adsorbing phosphorus impurities in trichlorosilane and its application in removing PCl3 in trichlorosilane.

[0023] Furthermore, an activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies is added to trichlorosilane, mixed and shaken, and then allowed to stand at 25-45° C. and filtered;

[0024] The ratio of the oxygen vacancy-rich activated carbon-supported vanadium oxide adsorbent to trichlorosilane is 0.25 g:100 mL-1.0 g:100 mL.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention uses ammonium metavanadate as a vanadium source and oxalic acid as a precipitant to prepare an activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies by an impregnation-calcination-reduction method. The present invention utilizes the complexation between ammonium metavanadate and oxalic acid to uniformly distribute vanadium ions in the pores of the activated carbon, avoiding agglomeration caused by excessive local concentration, thereby forming highly dispersed V after high-temperature calcination. x O yNanoparticles are loaded on the surface of activated carbon. Vanadium atoms have more unfilled d orbitals and can act as electron acceptors to bind PCl3 molecules through coordination. Vanadium oxide (VO x During the preparation process, oxygen vacancies can be manipulated to act as active sites, providing PCl₃ adsorption sites, thereby enhancing the adsorption capacity of the adsorbent. Leveraging its interaction with PCl₃, not only can trace amounts of PCl₃ be efficiently removed, but the adsorbent can also be regenerated and reused multiple times, reducing adsorbent consumption and saving economic costs, thus possessing excellent practical value.

[0027] Furthermore, in the present invention, by reacting with a metal oxide in a high-temperature reducing atmosphere, some of its lattice oxygen escapes during the reaction, forming oxygen vacancies. The presence of these oxygen vacancies not only enhances the chemical affinity for PCl3 by exposing unsaturated metal sites, but also strengthens the electronic interaction between the defect sites and P atoms through charge redistribution, significantly improving the adsorbent's adsorption performance for trace amounts of PCl3.

[0028] The activated carbon-supported vanadium oxide adsorbent used in this invention not only features a large specific surface area and a well-developed pore structure, but also exhibits excellent thermal stability after high-temperature modification. The introduced oxygen vacancies enhance the adsorbent's active sites for phosphorus impurities, significantly improving adsorption efficiency. Furthermore, the adsorbent was regenerated by maintaining the temperature at 120°C in nitrogen for 120 minutes. After four consecutive regeneration experiments, the adsorbent's adsorption efficiency for trace amounts of PCl3 decreased slightly, but by no more than 3%, fully demonstrating its excellent regeneration stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The comparison chart of phosphorus removal rate of adsorbents.

[0030] Figure 2 This is the data of four consecutive cycles of regeneration of activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies for the removal of trace PCl3. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in a variety of different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0032] Phosphorus impurities in trichlorosilane primarily exist as phosphorus trichloride. The phosphorus element in phosphorus trichloride is electron-rich and can stably bind to compounds containing electrophilic groups through covalent bonds, acting as a donor impurity. The oxygen-vacancy-rich activated carbon-supported vanadium oxide adsorbent provided by the present invention not only has the large specific surface area and well-developed pore structure of carbon materials, but also incorporates oxygen vacancies that act as active sites, providing additional adsorption sites for PCl3 molecules. These active sites can form stronger chemical bonds with PCl3 molecules, thereby improving the adsorption capacity of the adsorbent.

[0033] It should be noted that the formula for the phosphorus impurity removal rate in the present invention is:

[0034]

[0035] Among them, R e is the removal rate (%); C0 is the initial PCl3 concentration (μg / L); C e is the PCl3 concentration after adsorption (μg / L).

[0036] The present invention provides a method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane, comprising the steps of:

[0037] (1) Ammonium metavanadate (NH4VO3) and oxalic acid (H2C2O4·2H2O) were added to deionized water to prepare a solution. The activated carbon was immersed in the solution by an equal volume impregnation method and ultrasonically treated. The obtained sample was dried in an oven for 12 hours. After it was completely dried, a carbon material / vanadium oxide mixture was obtained.

[0038] In the present invention, ammonium metavanadate is used as a vanadium source and oxalic acid is used as a complexing agent.

[0039] The molar ratio of ammonium metavanadate and oxalic acid is 1:2.

[0040] The volume of the solution must ensure that the activated carbon is completely soaked and there is no obvious liquid phase layer.

[0041] (2) The carbon material / vanadium oxide mixture is placed in a tubular furnace, first calcined at high temperature in a nitrogen atmosphere, and then reduced using a hydrogen-argon mixture (10% H2 + 90% Ar by volume) to obtain an activated carbon-loaded vanadium oxide adsorbent rich in oxygen vacancies.

[0042] The vanadium loading amount (mass content) in the activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies is 1% to 7%.

[0043] The high temperature calcination temperature is 400-600°C and the time is 4-7h.

[0044] The temperature of the reduction treatment is 300-600°C and the time is 2-5h.

[0045] The activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies prepared by the present invention has a specific surface area of ​​689.47-904.0m 2 / g, porosity of 0.37-0.58cm 3 / g. Application of the activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies prepared by the present invention in removing trace PCl3 in trichlorosilane.

[0046] Specifically, an activated carbon-loaded vanadium oxide adsorbent rich in oxygen vacancies is added to trichlorosilane, mixed and shaken, and then allowed to stand at 25-45° C. and filtered to complete the removal of phosphorus impurities in trichlorosilane.

[0047] The ratio of the oxygen vacancy-rich activated carbon-supported vanadium oxide adsorbent to trichlorosilane is 0.5 g-1.0:100 mL.

[0048] The thermal desorption method is used to carry out the regeneration process. The specific operation is: after the activated carbon loaded with vanadium oxide adsorbent rich in oxygen vacancies adsorbs PCl3, it is calcined at 120°C for 2h under nitrogen protection, and then naturally cooled to regenerate the adsorbent.

[0049] The following are specific examples.

[0050] Example 1

[0051] 0.0129 g of ammonium metavanadate (NH4VO3) and 0.0278 g of oxalic acid were weighed separately to prepare a uniform solution, 1 g of activated carbon was immersed in the solution, and after ultrasonic immersion for 1 hour, a vanadium oxide / carbon material mixture was obtained; the vanadium oxide / carbon material mixture was dried in an oven at 100°C for 12 hours, and after being completely dried, it was transferred to a tubular furnace for calcination, and in a nitrogen atmosphere, the temperature was increased to 500°C at 10°C / min, and high-temperature calcined for 5 hours. After the tubular furnace was naturally cooled to room temperature, an activated carbon-supported vanadium oxide adsorbent was obtained, and the vanadium oxide loading was 1%. The obtained product was recorded as 1-V x O y / AC. The specific surface area of ​​the adsorbent is 904.0m 2 / g, porosity is 0.58cm 3 / g.

[0052] Take 0.5g of prepared V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 35ppb and the phosphorus impurity removal rate was 64.3%.

[0053] Example 2

[0054] 0.0386 g of ammonium metavanadate (NH4VO3) and 0.0832 g of oxalic acid were weighed separately to prepare a uniform solution, 1 g of activated carbon was immersed in the solution, and after ultrasonic immersion for 1 hour, a vanadium oxide / carbon material mixture was obtained; the vanadium oxide / carbon material mixture was dried in an oven at 100°C for 12 hours, and after being completely dried, it was transferred to a tube furnace for calcination, and in a nitrogen atmosphere, the temperature was increased to 500°C at 10°C / min and calcined for 5 hours. After the tube furnace was naturally cooled to room temperature, an activated carbon-supported vanadium oxide adsorbent was obtained, and the vanadium oxide loading was 3%. The obtained product was recorded as 3-V x O y / AC. The specific surface area of ​​the adsorbent is 854.3m 2 / g, porosity is 0.49cm 3 / g.

[0055] Take 0.5g of prepared V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 28ppb, the phosphorus impurity removal rate was 71.78%, the optimal loading was 3wt%, and the optimal calcination temperature was 500℃.

[0056] Example 3

[0057] 0.0643 g of ammonium metavanadate (NH4VO3) and 0.1386 g of oxalic acid were weighed separately to prepare a uniform solution, 1 g of activated carbon was immersed in the solution, and after ultrasonic immersion for 1 hour, a vanadium oxide / carbon material mixture was obtained; the vanadium oxide / carbon material mixture was dried in an oven at 100°C for 12 hours, and after being completely dried, it was transferred to a tubular furnace for calcination, and in a nitrogen atmosphere, the temperature was increased to 500°C at 10°C / min and calcined for 5 hours. After the tubular furnace was naturally cooled to room temperature, an activated carbon-supported vanadium oxide adsorbent was obtained, and the vanadium oxide loading was 5%. The obtained product was recorded as 5-V x O y / AC. The specific surface area of ​​the adsorbent is 736.4m 2 / g, porosity is 0.42cm 3 / g.

[0058] Take 0.5g of prepared V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 34ppb and the phosphorus impurity removal rate was 65.76%.

[0059] Example 4

[0060] 0.0643 g of ammonium metavanadate (NH4VO3) and 0.1386 g of oxalic acid were weighed separately to prepare a uniform solution, 1 g of activated carbon was immersed in the solution, and after ultrasonic immersion for 1 hour, a vanadium oxide / carbon material mixture was obtained; the vanadium oxide / carbon material mixture was dried in an oven at 100°C for 12 hours, and after being completely dried, it was transferred to a tubular furnace for calcination, and in a nitrogen atmosphere, the temperature was increased to 500°C at 10°C / min and calcined for 5 hours. After the tubular furnace was naturally cooled to room temperature, an activated carbon-supported vanadium oxide adsorbent was obtained, and the vanadium oxide loading was 7%. The obtained product was recorded as 7-V x O y / AC. The specific surface area of ​​the adsorbent is 689.5m 2 / g, porosity is 0.37cm 3 / g.

[0061] Take 0.5g of prepared V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 34ppb and the phosphorus impurity removal rate was 63.52%.

[0062] Example 5

[0063] The other conditions were the same as those in Example 3, except that the temperature in the tube furnace was raised to 400°C at a rate of 10°C / min and calcined for 5 h. The tube furnace was then allowed to cool naturally to room temperature. The resulting product was designated as 3-400-V x O y / AC.

[0064] Take 0.5g of prepared V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 30ppb and the phosphorus impurity removal rate was 69.39%.

[0065] Example 6

[0066] The other conditions were the same as those in Example 3, except that the temperature in the tube furnace was raised to 600°C at a rate of 10°C / min and calcined for 5 h. The tube furnace was then allowed to cool naturally to room temperature. The resulting product was designated as 3-600-V x O y / AC.

[0067] Take 0.5g of prepared V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 32.8ppb and the phosphorus impurity removal rate was 67.2%.

[0068] Example 7

[0069] The other conditions were the same as those in Example 3, except that after calcination, reduction was carried out in a hydrogen-argon mixed atmosphere. The reduction conditions were: hydrogen-argon mixed gas (volume fraction 10% H2 + 90% Ar), heating to 300°C at 10°C / min, reduction for 3 hours, and then allowing the tube furnace to cool naturally to room temperature. The resulting product was designated H300-V x O y / AC.

[0070] Take 0.5g of prepared H300-V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 27ppb and the phosphorus impurity removal rate was 72.39%.

[0071] Example 8

[0072] The other conditions were the same as those in Example 3, except that after calcination, the product was reduced in a hydrogen-argon mixed atmosphere. The reduction conditions were: hydrogen-argon mixed gas (10% H2 + 90% Ar), heating to 400°C at 10°C / min, reduction for 3 hours, and then cooling the tube furnace to room temperature. The resulting product was designated H400-V. x O y / AC.

[0073] Take 0.5g of prepared H400-V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 25ppb and the phosphorus impurity removal rate was 74.78%.

[0074] Example 9

[0075] The other conditions were the same as those in Example 3, except that after calcination, the product was reduced in a hydrogen-argon mixed atmosphere. The reduction conditions were: a hydrogen-argon mixed atmosphere (10% H2 + 90% Ar), heating to 500°C at a rate of 10°C / min, reduction for 3 hours, and then allowing the tube furnace to cool naturally to room temperature. The resulting product was designated H500-V. x O y / AC.

[0076] Take 0.5g of prepared H500-V x Oy / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 20ppb, the phosphorus impurity removal rate was 80.06%, and the optimal reduction temperature was 500℃.

[0077] Example 10

[0078] The other conditions were the same as those in Example 3, except that after calcination, the product was reduced in a hydrogen-argon mixed atmosphere. The reduction conditions were: hydrogen-argon mixed gas (10% H2 + 90% Ar), heating to 600°C at 10°C / min, reduction for 3 hours, and then cooling the tube furnace to room temperature. The resulting product was designated H600-V. x O y / AC.

[0079] Take 0.5g of prepared H600-V x O y / AC was added to 0.1L trichlorosilane containing 100ppb phosphorus impurities, mixed and shaken for 2h, allowed to stand for 30min and then filtered. After testing, the phosphorus impurity was 24ppb and the phosphorus impurity removal rate was 75.85%.

[0080] Example 11

[0081] Other conditions were the same as those in Example 7, except that the calcination temperature was 600° C., the calcination time was 4 h, and the reduction temperature was 350° C., the reduction time was 5 h.

[0082] Example 12

[0083] Other conditions were the same as those in Example 7, except that the calcination temperature was 400° C., the calcination time was 7 h, and the reduction temperature was 600° C., the reduction time was 2 h.

[0084] Comparative Example 1

[0085] Take 1g of commercial activated carbon and add it to 0.1L of trichlorosilane containing 100ppb phosphorus impurities, mix and shake for 2h. After standing for a period of time and filtering, the phosphorus impurities are detected to be 45.62ppb, and the phosphorus impurity removal rate is 54.38%.

[0086] The comparative results of the adsorption effects of the adsorbents of Examples 1-10 and Comparative Example 1 on phosphorus impurities are shown in Table 1.

[0087] Table 1 Comparison of adsorption effects of various adsorbents on phosphorus impurities

[0088]

[0089]

[0090] From Table 1 and Figure 1 It can be seen that the oxygen vacancy-rich activated carbon-loaded vanadium oxide prepared by the present invention has a good adsorption effect on phosphorus impurities in trichlorosilane as an adsorbent. The overall adsorption effect of each of the provided oxygen vacancy-rich activated carbon-loaded vanadium oxide adsorbents on boron impurities is better than that of natural activated carbon. The oxygen vacancies introduced in the present invention can serve as active sites, providing additional adsorption sites for PCl3 molecules to adsorb. These active sites can form stronger chemical bonds with PCl3 molecules, thereby improving the adsorption capacity of the adsorbent. The adsorbent with a phosphorus removal rate of 80% contains a higher concentration of oxygen vacancies, indicating that the presence of oxygen vacancies has a good adsorption effect on phosphorus impurities.

[0091] H500-V was prepared by the method described in Example 8 x O y / AC adsorbent, 0.5g of the prepared adsorbent was added to 0.1L 100ppb trichlorosilane containing phosphorus impurities, and the mixture was mixed and shaken for 10min, 20min, 30min, 60min, 120min and 180min respectively. After standing for 30min, it was filtered. It was found through testing (please refer to Table 2 for details) that within the first 30 minutes after the adsorption began, the adsorption process was particularly rapid, and the removal rate of PCl3 by the adsorbent could reach more than 74.80%. As the adsorption time increased, the active sites on the outer surface gradually became saturated, the adsorption process slowly proceeded to the pores of the carrier, and the adsorption rate slowly increased. When the adsorption time was further extended, it was found that the adsorption removal rate did not increase significantly, indicating that it was close to the adsorption equilibrium at this time, and the adsorption rate and desorption rate reached a dynamic balance.

[0092] Table 2 Comparison of adsorption effect of adsorption time on phosphorus impurities

[0093]

[0094] H500-V was prepared by the method described in Example 8 x O y / AC adsorbent, 0.5g of the prepared adsorbent was added to 0.1L of trichlorosilane containing 100ppb phosphorus impurities, and the mixture was shaken for 2h at adsorption temperatures of 25℃, 35℃, and 45℃, respectively. After standing for 30min, it was filtered. After testing (see Table 3 for details), the removal rate of trace PCl3 by the adsorbent decreased significantly as the adsorption temperature increased from 25℃ to 45℃. This is because low temperature may reduce the desorption rate, thereby retaining more adsorbate in dynamic equilibrium. High temperature will cause problems such as active site deactivation and aggravation of side reactions. Therefore, high temperature is not conducive to the removal of trace PCl3. Experimental studies at lower temperatures are conducive to the efficient removal of PCl3 by this adsorbent.

[0095] Table 3 Comparison of adsorption effect of adsorption temperature on phosphorus impurities

[0096]

[0097] The method described in Example 8 was used to prepare H500-V x O y For the AC adsorbent, 0.25g, 0.5g, 0.75g, and 1g of each prepared adsorbent were added to 0.1L of trichlorosilane containing 100 ppb phosphorus impurities. The mixture was shaken for 2 hours, allowed to stand for 30 minutes, and then filtered. Testing revealed (see Table 4 for details) that with increasing adsorbent dosage, adsorption performance significantly improved within the 0.25g to 0.5g range. However, within the 0.5g to 0.75g range, the relative improvement in adsorption performance gradually decreased, and the growth subsequently slowed. This indicates that increasing adsorbent dosage can effectively improve adsorption performance within a certain range, but the performance improvement becomes limited when the adsorbent approaches saturation.

[0098] Table 4 Comparison of adsorbent dosage on adsorption effect of phosphorus impurities

[0099]

[0100] The above description is merely a description of the preferred embodiment of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiment, and variations in the specific structure are permitted. Any variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane, characterized in that: The following steps are involved: The activated carbon was immersed in a solution containing ammonium metavanadate and oxalic acid, subjected to ultrasonic treatment, and dried to obtain an activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies.

2. The method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane according to claim 1, characterized in that: The activated carbon was immersed in a solution containing ammonium metavanadate and oxalic acid using an equal volume impregnation method.

3. The method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane according to claim 1, characterized in that: The molar ratio of ammonium metavanadate and oxalic acid is 1:

2.

4. The method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane according to claim 1, characterized in that: Calcination was carried out in a nitrogen atmosphere.

5. The method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane according to claim 1, characterized in that: The calcination temperature is 400-600°C and the time is 4-7h.

6. The method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane according to claim 1, characterized in that: Also includes: The activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies was subjected to reduction treatment.

7. The method for preparing an adsorbent for adsorbing phosphorus impurities in trichlorosilane according to claim 6, characterized in that: The reduction treatment was carried out in a mixed atmosphere of hydrogen and argon, with the volume percentage of H2 being 10%; The temperature of the reduction treatment is 300-600°C and the time is 2-5h.

8. An adsorbent for adsorbing phosphorus impurities in trichlorosilane prepared by the method according to any one of claims 1 to 7, characterized in that: The mass loading of vanadium in the adsorbent is 1% to 7%, and the specific surface area of ​​the adsorbent is 689.47 m 2 / g-904.0m 2 / g, porosity is 0.37cm 3 / g-0.58cm 3 / g.

9. Use of an adsorbent for adsorbing phosphorus impurities in trichlorosilane prepared by the method according to any one of claims 1 to 7 in removing PCl3 from trichlorosilane.

10. The use according to claim 9, characterized in that Adding an activated carbon-supported vanadium oxide adsorbent rich in oxygen vacancies to trichlorosilane, mixing and shaking, standing at 25-45°C, and filtering; The ratio of the oxygen vacancy-rich activated carbon-supported vanadium oxide adsorbent to trichlorosilane is 0.25 g:100 mL-1.0 g:100 mL.

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