Preparation method of adsorbent

Abstract

The present invention discloses a preparation method of an adsorbent. The preparation method includes: dissolving FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; adding a silane precursor to molten paraffin and mixing to obtain an oil phase mixture; mixing the oil phase mixture with the aqueous phase mixture and adding an alkaline initiator to carry out a stirring reaction to obtain microcapsules; removing the paraffin in the microcapsules to obtain the adsorbent. The adsorbent prepared by the method in the present invention can adsorb metal impurities in trichlorosilane and improve the adsorption effect of the adsorbent on impurities in trichlorosilane.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorbents, and particularly relates to a preparation method of an adsorbent. Background Art

[0002] Due to the rapid consumption of non-renewable energy sources such as coal and petroleum, energy depletion and environmental problems have become increasingly serious. From the perspective of sustainable development, the use of renewable energy sources such as solar energy has become an important choice for human development. High-purity polysilicon, as the upstream raw material of the photovoltaic industry, plays a crucial role in the entire photovoltaic industry. High-purity trichlorosilane, as the main raw material for producing polysilicon, its quality plays a vital role in the quality of polysilicon. At present, the main types of impurities in trichlorosilane are substances such as B, P, C, and metals. Among them, metals are an important factor affecting the purity of polysilicon. Due to the disadvantages of high energy consumption and easy pollution of the traditional rectification method, the method of using adsorption to remove impurities from trichlorosilane has received increasing attention. However, the existing adsorbents have poor adsorption effects on the impurities in trichlorosilane, which affects the quality of polysilicon products. Summary of the Invention

[0003] The purpose of the embodiments of the present invention is to provide a preparation method of an adsorbent to solve the problem that the existing adsorbent has poor adsorption effect on the impurities in trichlorosilane.

[0004] In a first aspect, the embodiments of the present invention provide a preparation method of an adsorbent, including:

[0005] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture;

[0006] Add a silane precursor to molten paraffin and mix to obtain an oil phase mixture;

[0007] Mix the oil phase mixture with the aqueous phase mixture and add an alkaline initiator to stir and react to obtain microcapsules;

[0008] Remove the paraffin in the microcapsules to obtain the adsorbent.

[0009] Optionally, the molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:(2 - 2.5); and / or

[0010] The mass ratio of paraffin to the silane precursor is 10:(1 - 10); and / or

[0011] The mass of FeCl2·4H2O and FeCl3·6H2O accounts for 3% - 44% of the mass of the silane precursor.

[0012] Optionally, the temperature of the mixing reaction of the oil phase mixture and the aqueous phase mixture is 30 - 200°C; and / or

[0013] The mixing reaction time of the oil-phase mixture and the water-phase mixture is 2 - 8 h.

[0014] Optionally, the mass ratio of the basic initiator to the silane precursor is (2 - 39) : 100.

[0015] Optionally, the solvent includes water and ethanol; and / or

[0016] The basic initiator includes at least one of ammonia water, urea, ethylenediamine, sodium hydroxide, and potassium hydroxide.

[0017] Optionally, the step of mixing the oil-phase mixture and the water-phase mixture and adding a basic initiator for stirring reaction to obtain microcapsules includes:

[0018] Mix the oil-phase mixture and the water-phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0019] Wash and dry the reaction product to obtain microcapsules.

[0020] Optionally, the step of washing and drying the reaction product includes:

[0021] Wash the reaction product with a washing solution, and the washing solution includes water and ethanol;

[0022] Dry the washed reaction product at 60 - 120 °C.

[0023] Optionally, the step of removing paraffin in the microcapsules to obtain an adsorbent includes:

[0024] Soak the microcapsules in a paraffin dissolving agent for 16 - 48 h;

[0025] Wash the soaked microcapsules and dry them at 60 - 90 °C to obtain an adsorbent.

[0026] Optionally, the step of removing paraffin in the microcapsules to obtain an adsorbent includes:

[0027] Place the microcapsules in a first atmosphere and heat them to a first temperature at a first heating rate and calcine them at the first temperature for 0.5 - 1.5 h;

[0028] Place the microcapsules treated at the first temperature in a second atmosphere and heat them from the first temperature to a second temperature at a second heating rate and calcine them at the second temperature for 1 - 3 h;

[0029] Place the microcapsules treated at the second temperature in a third atmosphere and heat them from the second temperature to a third temperature at a third heating rate and calcine them at the third temperature for 0.5 - 1.5 h;

[0030] The microcapsules treated at the third temperature are placed in the fourth atmosphere and heated from the third temperature to the fourth temperature at the fourth heating rate, and calcined at the fourth temperature for 1 - 3 h;

[0031] Wherein, the first temperature is 280 - 300 °C, the second temperature is 480 - 500 °C, the third temperature is 700 - 750 °C, and the fourth temperature is 820 - 950 °C;

[0032] The first heating rate is 3 - 6 °C / min, the second heating rate is 1.5 - 2.5 °C / min, the third heating rate is 0.5 - 1 °C / min, and the fourth heating rate is 0.5 - 1 °C / min;

[0033] The first atmosphere, the second atmosphere, the third atmosphere and the fourth atmosphere are all inert atmospheres; or

[0034] The first atmosphere is an inert atmosphere, the second atmosphere is an oxidizing atmosphere, the third atmosphere is an inert atmosphere, and the fourth atmosphere is an inert atmosphere.

[0035] Optionally, the preparation method further includes:

[0036] Washing the adsorbent in an acidic solvent.

[0037] Optionally, after removing the paraffin in the microcapsules, it further includes:

[0038] Soaking the adsorbent in an alkaline solution and drying.

[0039] In a second aspect, an adsorbent provided by an embodiment of the present invention is prepared by using the method described in the above embodiment.

[0040] The preparation method of the adsorbent according to the embodiment of the present invention includes: dissolving FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; adding a silane precursor to molten paraffin and mixing to obtain an oil phase mixture; mixing the oil phase mixture with the aqueous phase mixture and adding an alkaline initiator to carry out a stirring reaction to obtain microcapsules; removing the paraffin in the microcapsules to obtain the adsorbent. During the preparation of the adsorbent, the aqueous phase mixture dissolving FeCl2·4H2O and FeCl3·6H2O is stirred and reacted with the oil phase mixture having paraffin and a silane precursor under alkaline conditions to obtain microcapsules, and the paraffin in the microcapsules is removed to obtain the adsorbent. By adding FeCl2·4H2O and FeCl3·6H2O, Fe3O4 particles can be generated during the hydrolysis of the silane precursor to form microcapsules, so that the microcapsules are dispersed with Fe3O4 particles. The Fe3O4 particles are evenly dispersed and have magnetism. During the process of adsorbing B and P impurities in trichlorosilane, the adsorbent can adsorb metal impurities in trichlorosilane, improving the adsorption effect of the adsorbent on impurities in trichlorosilane and the adsorption efficiency. Detailed Description of the Invention

[0041] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0042] The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention can be implemented in an order other than those described herein. In addition, "and / or" in the specification and claims means at least one of the connected objects. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0043] The following will specifically describe the preparation method of the adsorbent provided by the embodiment of the present invention through specific embodiments.

[0044] The preparation method of the adsorbent according to the embodiment of the present invention includes:

[0045] Dissolving FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture;

[0046] Adding a silane precursor to molten paraffin and mixing to obtain an oil phase mixture;

[0047] Mix the oil-phase mixture with the water-phase mixture and add an alkaline initiator, then stir to react to obtain microcapsules; the stirring speed can be 300 rpm / min.

[0048] Remove the paraffin in the microcapsules to obtain the adsorbent.

[0049] The solvent can include water and ethanol. FeCl2·4H2O and FeCl3·6H2O are dissolved in the solvent. Fe 2+ and Fe 3+ Under alkaline conditions, Fe3O4 can be generated. The molten paraffin and the silane precursor are mixed and can form microcapsules coated with paraffin under alkaline conditions. Therefore, Fe3O4 and the microcapsules can be carried out in the same reaction process, avoiding directly adding Fe3O4 particles during the formation of microcapsules and preventing particle agglomeration. The Fe3O4 microparticles in the microcapsules are generated and have smaller particle size and good dispersibility, making the pores of the microcapsules uniform. During the preparation of the magnetic adsorbent, the steps of pre-synthesizing and adding magnetic particles can be reduced, simplifying the synthesis method while enhancing the bonding strength at the interfaces of different materials of the adsorbent by in-situ synthesizing magnetic particles.

[0050] During the process of removing the paraffin in the microcapsules, the microcapsules can be placed in a solvent capable of dissolving paraffin to dissolve and remove the paraffin in the microcapsules, or the microcapsules can be placed in the vapor of a solvent capable of dissolving paraffin to dissolve and remove the paraffin in the microcapsules, which can improve the removal effect and efficiency.

[0051] During the preparation of the adsorbent, the water-phase mixture dissolving FeCl2·4H2O and FeCl3·6H2O is stirred and reacted with the oil-phase mixture containing paraffin and the silane precursor under alkaline conditions to obtain microcapsules, and the paraffin in the microcapsules is removed to obtain the adsorbent. By adding FeCl2·4H2O and FeCl3·6H2O, Fe3O4 microparticles can be generated during the hydrolysis of the silane precursor to form microcapsules, so that the microcapsules are dispersed with Fe3O4 microparticles. The Fe3O4 microparticles are evenly dispersed and have magnetism. During the process of the adsorbent adsorbing B and P impurities in trichlorosilane, it can also adsorb metal impurities in trichlorosilane, improving the adsorption effect and efficiency of the adsorbent for impurities in trichlorosilane.

[0052] In some embodiments, the molar ratio of FeCl2·4H2O to FeCl3·6H2O can be 1:(2 - 2.5); for example, the molar ratio of FeCl2·4H2O to FeCl3·6H2O can be 1:2.

[0053] Optionally, the mass ratio of paraffin to the silane precursor can be 10:(1 - 10); for example, the mass ratio of paraffin to the silane precursor can be 10:1 or 5:1.

[0054] Optionally, the mass of FeCl2·4H2O and FeCl3·6H2O accounts for 3%-45% of the mass of the silane precursor. For example, the sum of the mass of FeCl2·4H2O and FeCl3·6H2O can account for 3% of the mass of the silane precursor.

[0055] In some embodiments, the temperature of the mixing reaction of the oil-phase mixture and the water-phase mixture can be 30-200 °C.

[0056] Optionally, the mixing reaction time of the oil-phase mixture and the water-phase mixture is 2-8 h.

[0057] During the mixing reaction of the oil-phase mixture and the water-phase mixture, the oil-phase mixture and the water-phase mixture can be mixed and an alkaline initiator can be added to carry out a stirring reaction at a first temperature for 1-3 h, and the stirring speed can be 800 rpm / min, and then a stirring reaction can be carried out at a second temperature for 2-5 h, and the stirring speed can be 300-1500 rpm / min to obtain microcapsules. For example, the first temperature can be 30-70 °C, and the second temperature can be 90-160 °C. An emulsifier can be added during the mixing reaction of the oil-phase mixture and the water-phase mixture, and emulsification can be carried out through the emulsifier. The emulsifier can be cetyltrimethylammonium bromide (CTAB). The emulsifier can be added to the water-phase mixture, and the mass ratio of the emulsifier to the silane precursor can be 1:(1.8-3). For example, the mass ratio of the emulsifier to the silane precursor can be 1:2.

[0058] In some embodiments, the mass ratio of the alkaline initiator to the silane precursor can be (2-39):100.

[0059] Optionally, the solvent can include water and ethanol.

[0060] Optionally, the alkaline initiator can include at least one of ammonia water, urea, ethylenediamine, sodium hydroxide, and potassium hydroxide.

[0061] In the embodiments of the present invention, the step of mixing the oil-phase mixture and the water-phase mixture and adding an alkaline initiator to carry out a stirring reaction to obtain microcapsules can include:

[0062] Mix the oil-phase mixture and the water-phase mixture and add ammonia water to carry out a stirring reaction to obtain a reaction product;

[0063] Wash and dry the reaction product to obtain microcapsules.

[0064] The residual ammonia water after the reaction is easy to remove and is not likely to introduce new impurities.

[0065] Impurities on the reaction product can be removed by washing, and residues on the microcapsules can be removed by drying after washing.

[0066] Optionally, the steps of washing and drying the reaction product may include:

[0067] Washing the reaction product with a washing solution, the washing solution including water and ethanol;

[0068] Drying the washed reaction product at 60 - 120 °C.

[0069] Impurity residues can be effectively removed by washing and drying. FeCl2·4H2O and FeCl3·6H2O are dissolved in a solvent, the solvent can include water and ethanol, the washing solution includes water and ethanol, the components of the solvent and the washing solution can be the same, and no new impurities will be introduced during the washing process. The volume ratio of water to ethanol can be 1:(1 - 2). For example, the volume ratio of water to ethanol can be 1:1.

[0070] In the embodiments of the present invention, the steps of removing paraffin in the microcapsules to obtain an adsorbent may include:

[0071] Soaking the microcapsules in a paraffin solvent for 16 - 48 h;

[0072] Washing the soaked microcapsules and drying at 60 - 90 °C to obtain an adsorbent.

[0073] The paraffin solvent may include at least one of acetone, gasoline, petroleum ether, ether, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, tetrahydrofuran, xylene, chloroform, carbon tetrachloride, carbon disulfide, furfural. The paraffin may include at least one of animal wax, plant wax, mineral wax, petroleum wax, synthetic wax. For example, the paraffin solvent may include acetone or petroleum ether, and the paraffin may be petroleum wax.

[0074] During the process of soaking the microcapsules in the paraffin solvent, the paraffin solvent can be ultrasonically treated so that the solvent can enter the microcapsules and improve the removal efficiency.

[0075] The steps of removing paraffin in the microcapsules to obtain an adsorbent may include:

[0076] Treating the microcapsules in the vapor of the paraffin solvent for 8 - 36 h;

[0077] Washing the microcapsules after vapor treatment and drying at 60 - 90 °C to obtain an adsorbent.

[0078] The vapor can better enter the pores, and removing the paraffin in the microcapsules by the vapor of the paraffin solvent can improve the removal effect and efficiency.

[0079] In some embodiments of the present invention, the step of removing paraffin in the microcapsules to obtain the adsorbent may include:

[0080] Placing the microcapsules in a first atmosphere and heating them to a first temperature at a first heating rate and calcining them at the first temperature for 0.5 - 1.5 h;

[0081] Placing the microcapsules treated at the first temperature in a second atmosphere and heating them from the first temperature to a second temperature at a second heating rate and calcining them at the second temperature for 1 - 3 h;

[0082] Placing the microcapsules treated at the second temperature in a third atmosphere and heating them from the second temperature to a third temperature at a third heating rate and calcining them at the third temperature for 0.5 - 1.5 h;

[0083] Placing the microcapsules treated at the third temperature in a fourth atmosphere and heating them from the third temperature to a fourth temperature at a fourth heating rate and calcining them at the fourth temperature for 1 - 3 h;

[0084] Wherein, the first temperature is 280 - 300 °C, the second temperature is 480 - 500 °C, the third temperature is 700 - 750 °C, and the fourth temperature is 820 - 950 °C;

[0085] The first heating rate is 3 - 6 °C / min, the second heating rate is 1.5 - 2.5 °C / min, the third heating rate is 0.5 - 1 °C / min, and the fourth heating rate is 0.5 - 1 °C / min;

[0086] The first atmosphere, the second atmosphere, the third atmosphere and the fourth atmosphere are all inert atmospheres; or

[0087] The first atmosphere is an inert atmosphere, the second atmosphere is an oxidizing atmosphere, the third atmosphere is an inert atmosphere, and the fourth atmosphere is an inert atmosphere.

[0088] Through calcination, paraffin in the microcapsules can be removed. Through calcination, organic substances can be effectively removed, the pores in the adsorbent can be improved, the adsorption sites in the adsorbent can be activated and increased, and no solvent is required.

[0089] During the calcination process, the first atmosphere is an inert atmosphere, the second atmosphere is an oxidizing atmosphere, the third atmosphere is an inert atmosphere, and the fourth atmosphere is an inert atmosphere. By selecting the second atmosphere as an oxidizing atmosphere, after most of the organic substances are removed in an inert environment, the carbon remaining after the carbonization of the organic substances can be removed by oxidation with oxygen, so that oxygen reacts with carbon or the remaining organic substances to generate carbon monoxide or carbon dioxide, reducing the carbon residue. The third atmosphere is an inert atmosphere, and the fourth atmosphere is an inert atmosphere. Continuing to calcine at a high temperature can increase the adsorption sites, which is beneficial to adsorbing impurities.

[0090] In some embodiments, the preparation method may further include:

[0091] Washing the adsorbent in an acidic solvent.

[0092] During the formation of the microcapsules, a small amount of Fe3O4 particles will be exposed on the surface of the microcapsules. The exposed Fe3O4 particles can be removed by washing with an acidic solvent to prevent the Fe3O4 particles from contaminating trichlorosilane. The acidic solvent may include at least one of an aqueous hydrochloric acid solution, an aqueous nitric acid solution, and an aqueous sulfuric acid solution. For example, the acidic solvent may include an aqueous hydrochloric acid solution because hydrogen chloride will be utilized or generated during the trichlorosilane and polysilicon preparation processes. Using hydrochloric acid to remove the exposed Fe3O4 particles can avoid the introduction of other impurities.

[0093] After washing the adsorbent in an acidic solvent, it may further include: washing with deionized water and drying after washing.

[0094] After washing with deionized water and drying, it further includes:

[0095] The adsorbent can be soaked in 50 mL of an alkaline solution for 16 - 36 h, taken out and dried for 24 - 48 h to obtain the adsorbent.

[0096] In some embodiments, after removing the paraffin in the microcapsules, it may further include:

[0097] Soaking the adsorbent in an alkaline solution and drying.

[0098] The alkaline solution includes but is not limited to NaOH, KOH, Ba(OH)2, etc. The alkaline solution can be an aqueous solution of sodium hydroxide, and the concentration of sodium hydroxide can be 1 - 5 mol / l.

[0099] During the process of the adsorbent adsorbing impurities in trichlorosilane, as the adsorption amount and adsorption time increase, the adsorption performance of the adsorbent decreases, and the adsorbent can be regenerated.

[0100] During the regeneration process of the adsorbent, the regeneration method may include:

[0101] Placing the adsorbent to be regenerated at 90 - 180 °C and treating it in a nitrogen environment or a vacuum environment for 4 - 36 h;

[0102] Placing the adsorbent at 260 - 450 °C and treating it in a nitrogen environment or a vacuum environment for 8 - 24 h;

[0103] Placing the adsorbent at 120 - 240 °C and treating it in an oxidizing atmosphere for 4 - 28 h;

[0104] The oxidizing atmosphere can be a mixture of nitrogen and oxygen. For example, the mass of oxygen can be 3-12% of the mass of the mixture, and the mass of oxygen can be 5% of the mass of the mixture.

[0105] The adsorbent regenerated as described above can adsorb B, P, and metal impurities in trichlorosilane. The regenerated adsorbent has good adsorption effect and can be recycled.

[0106] After treating the adsorbent at 150-200 °C in an oxidizing atmosphere for 4-28 h, the regeneration method may further include:

[0107] Washing the adsorbent in an acidic solvent.

[0108] During the adsorption process, a small amount of Fe3O4 particles will be exposed on the surface of the adsorbent. The exposed Fe3O4 particles can be removed by washing with an acidic solvent to prevent the Fe3O4 particles from contaminating trichlorosilane. The acidic solvent may include at least one of hydrochloric acid aqueous solution, nitric acid aqueous solution, and sulfuric acid aqueous solution. For example, the acidic solvent may include hydrochloric acid aqueous solution because hydrogen chloride will be utilized or generated during the preparation processes of trichlorosilane and polysilicon. Using hydrochloric acid to remove the exposed Fe3O4 particles can avoid the introduction of other impurities.

[0109] After washing the adsorbent in an acidic solvent, it may further include: washing with deionized water and then drying after washing.

[0110] After treating the adsorbent at 150-200 °C in an oxidizing atmosphere for 4-28 h, the regeneration method may further include: treating the adsorbent at 90-130 °C in ammonia for 1-2 h;

[0111] The reaction of organic matter with oxygen can generate some water. Ammonia can enter the pores, and ammonia combines with water molecules to form alkaline ammonia water, enabling the adsorbent to increase alkaline adsorption sites.

[0112] The present invention will be further described below through some specific embodiments.

[0113] Example 1

[0114] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; add 5 g of cetyltrimethylammonium bromide (CTAB) to the aqueous phase mixture;

[0115] Add tetraethyl orthosilicate (TEOS) to molten paraffin and mix to obtain an oil phase mixture;

[0116] Mix the oil phase mixture and the aqueous phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0117] Wash and dry the reaction product. The washing solution includes water and ethanol;

[0118] Dry the washed reaction product at 60 °C to obtain microcapsules;

[0119] Soak the microcapsules in a paraffin dissolving agent for 48 h;

[0120] Wash the soaked microcapsules and dry them at 90 °C to obtain an adsorbent;

[0121] Among them, the solvent includes water and ethanol, the volume ratio of water to ethanol is 1:1, the molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:2, the amount of FeCl2·4H2O is 0.0025 mol, the mass ratio of paraffin to tetraethyl orthosilicate is 10:1, and the mass of FeCl2·4H2O and FeCl3·6H2O accounts for 43.6% of the mass of tetraethyl orthosilicate;

[0122] The temperature for the mixing reaction of the oil-phase mixture and the water-phase mixture is 30 °C, the reaction time is 8 h, and the mass ratio of ammonia water to tetraethyl orthosilicate is 39%.

[0123] Example 2

[0124] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous-phase mixture; add 5 g of cetyltrimethylammonium bromide (CTAB) to the aqueous-phase mixture;

[0125] Add tetraethyl orthosilicate (TEOS) to the melted paraffin and mix to obtain an oil-phase mixture;

[0126] Mix the oil-phase mixture and the aqueous-phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0127] Wash and dry the reaction product. The washing solution includes water and ethanol;

[0128] Dry the washed reaction product at 120 °C to obtain microcapsules;

[0129] Soak the microcapsules in a paraffin dissolving agent for 16 h;

[0130] Wash the soaked microcapsules and dry them at 60 °C to obtain an adsorbent;

[0131] Among them, the solvent includes water and ethanol, the volume ratio of water to ethanol is 1:1, the molar ratio of FeCl₂·4H₂O to FeCl₃·6H₂O is 1:2.5, the amount of FeCl₂·4H₂O is 0.0025 mol, the mass ratio of paraffin to tetraethyl orthosilicate is 10:1, and the mass of FeCl₂·4H₂O and FeCl₃·6H₂O accounts for 43.6% of the mass of tetraethyl orthosilicate;

[0132] The temperature for the mixing reaction of the oil-phase mixture and the water-phase mixture is 200 °C, the reaction time is 2 h, and the mass ratio of ammonia water to tetraethyl orthosilicate is 26%.

[0133] Example 3

[0134] Dissolve FeCl₂·4H₂O and FeCl₃·6H₂O in the solvent to obtain an aqueous-phase mixture; add 5 g of cetyltrimethylammonium bromide (CTAB) to the aqueous-phase mixture;

[0135] Add tetraethyl orthosilicate (TEOS) to the melted paraffin and mix to obtain an oil-phase mixture;

[0136] Mix the oil-phase mixture and the aqueous-phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0137] Wash and dry the reaction product, and the washing solution includes water and ethanol;

[0138] Dry the washed reaction product at 60 °C to obtain microcapsules;

[0139] Soak the microcapsules in a paraffin dissolving agent for 36 h;

[0140] Wash the soaked microcapsules and dry them at 60 °C to obtain an adsorbent;

[0141] Among them, the solvent includes water and ethanol, the volume ratio of water to ethanol is 1:1, the molar ratio of FeCl₂·4H₂O to FeCl₃·6H₂O is 1:2.5, the amount of FeCl₂·4H₂O is 0.0025 mol, the mass ratio of paraffin to tetraethyl orthosilicate is 5:1, and the mass of FeCl₂·4H₂O and FeCl₃·6H₂O accounts for 22.7% of the mass of tetraethyl orthosilicate;

[0142] The temperature for the mixing reaction of the oil-phase mixture and the water-phase mixture is 100 °C, the reaction time is 5 h, and the mass ratio of ammonia water to tetraethyl orthosilicate is 26%.

[0143] Example 4

[0144] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; add 10 g of cetyltrimethylammonium bromide (CTAB) to the aqueous phase mixture;

[0145] Add tetraethyl orthosilicate (TEOS) to molten paraffin and mix to obtain an oil phase mixture;

[0146] Mix the oil phase mixture and the aqueous phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0147] Wash and dry the reaction product, and the washing liquid includes water and ethanol;

[0148] Dry the washed reaction product at 60 °C to obtain microcapsules;

[0149] Soak the microcapsules in a paraffin dissolving agent for 24 h;

[0150] Wash the soaked microcapsules and dry them at 90 °C to obtain an adsorbent;

[0151] Among them, the solvent includes water and ethanol, the volume ratio of water and ethanol is 1:1, the molar ratio of FeCl2·4H2O and FeCl3·6H2O is 1:2, FeCl2·4H2O is 0.0025 mol, the mass ratio of paraffin and tetraethyl orthosilicate is 10:1, and the mass of FeCl2·4H2O and FeCl3·6H2O accounts for 3% of the mass of tetraethyl orthosilicate;

[0152] The temperature of the mixing reaction of the oil phase mixture and the aqueous phase mixture is 30 °C, the reaction time is 8 h, and the mass ratio of ammonia water and tetraethyl orthosilicate is 2%.

[0153] Example 5

[0154] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; add 5 g of cetyltrimethylammonium bromide (CTAB) to the aqueous phase mixture;

[0155] Add tetraethyl orthosilicate (TEOS) to molten paraffin and mix to obtain an oil phase mixture;

[0156] Mix the oil phase mixture and the aqueous phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0157] Wash and dry the reaction product, and the washing liquid includes water and ethanol;

[0158] Dry the washed reaction product at 60 °C to obtain microcapsules;

[0159] Among them, the solvent includes water and ethanol, the volume ratio of water to ethanol is 1:1, the molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:2, the amount of FeCl2·4H2O is 0.0025 mol, the mass ratio of paraffin to tetraethyl orthosilicate is 10:1, and the mass of FeCl2·4H2O and FeCl3·6H2O accounts for 43.6% of the mass of tetraethyl orthosilicate;

[0160] The temperature for the mixing reaction of the oil-phase mixture and the water-phase mixture is 120 °C, the reaction time is 6 h, and the mass ratio of ammonia water to tetraethyl orthosilicate is 39%;

[0161] The microcapsules are placed in a first atmosphere and heated to a first temperature at a first heating rate and calcined at the first temperature for 0.5 h;

[0162] The microcapsules treated at the first temperature are placed in a second atmosphere and heated from the first temperature to a second temperature at a second heating rate and calcined at the second temperature for 3 h;

[0163] The microcapsules treated at the second temperature are placed in a third atmosphere and heated from the second temperature to a third temperature at a third heating rate and calcined at the third temperature for 0.5 h;

[0164] The microcapsules treated at the third temperature are placed in a fourth atmosphere and heated from the third temperature to a fourth temperature at a fourth heating rate and calcined at the fourth temperature for 1 h;

[0165] Among them, the first temperature is 280 °C, the second temperature is 500 °C, the third temperature is 750 °C, and the fourth temperature is 950 °C;

[0166] The first heating rate is 3 °C / min, the second heating rate is 1.5 °C / min, the third heating rate is 1 °C / min, and the fourth heating rate is 0.5 °C / min;

[0167] The first atmosphere, the second atmosphere, the third atmosphere and the fourth atmosphere are all inert atmospheres, and the inert atmosphere is nitrogen.

[0168] Example 6

[0169] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous-phase mixture; add 5 g of cetyltrimethylammonium bromide (CTAB) to the aqueous-phase mixture;

[0170] Add tetraethyl orthosilicate (TEOS) to the molten paraffin and mix to obtain an oil-phase mixture;

[0171] Mix the oil-phase mixture and the aqueous-phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0172] The reaction product is washed and dried, and the washing liquid includes water and ethanol;

[0173] The washed reaction product is dried at 60 °C to obtain microcapsules;

[0174] Among them, the solvent includes water and ethanol, the volume ratio of water to ethanol is 1:1, the molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:2, FeCl2·4H2O is 0.0025 mol, the mass ratio of paraffin to tetraethyl orthosilicate is 10:1, and the mass of FeCl2·4H2O and FeCl3·6H2O accounts for 43.6% of the mass of tetraethyl orthosilicate;

[0175] The temperature for the mixed reaction of the oil-phase mixture and the water-phase mixture is 120 °C, the reaction time is 6 h, and the mass ratio of ammonia water to tetraethyl orthosilicate is 39%;

[0176] The microcapsules are placed in a first atmosphere and heated to a first temperature at a first heating rate and calcined at the first temperature for 1.5 h;

[0177] The microcapsules treated at the first temperature are placed in a second atmosphere and heated from the first temperature to a second temperature at a second heating rate and calcined at the second temperature for 1 h;

[0178] The microcapsules treated at the second temperature are placed in a third atmosphere and heated from the second temperature to a third temperature at a third heating rate and calcined at the third temperature for 1.5 h;

[0179] The microcapsules treated at the third temperature are placed in a fourth atmosphere and heated from the third temperature to a fourth temperature at a fourth heating rate and calcined at the fourth temperature for 3 h;

[0180] Among them, the first temperature is 300 °C, the second temperature is 480 °C, the third temperature is 700 °C, and the fourth temperature is 820 °C;

[0181] The first heating rate is 6 °C / min, the second heating rate is 2.5 °C / min, the third heating rate is 0.5 °C / min, and the fourth heating rate is 1 °C / min;

[0182] The first atmosphere, the second atmosphere, the third atmosphere and the fourth atmosphere are all inert atmospheres, and the inert atmosphere is nitrogen.

[0183] Example 7

[0184] Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; add 5 g of cetyltrimethylammonium bromide (CTAB) to the aqueous phase mixture;

[0185] Add tetraethyl orthosilicate (TEOS) to molten paraffin and mix to obtain an oil phase mixture;

[0186] Mix the oil phase mixture and the aqueous phase mixture and add ammonia water for stirring reaction to obtain a reaction product;

[0187] Wash and dry the reaction product, and the washing liquid includes water and ethanol;

[0188] Dry the washed reaction product at 60 °C to obtain microcapsules;

[0189] Among them, the solvent includes water and ethanol, the volume ratio of water to ethanol is 1:1, the molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:2, FeCl2·4H2O is 0.0025 mol, the mass ratio of paraffin to tetraethyl orthosilicate is 10:1, and the mass of FeCl2·4H2O and FeCl3·6H2O accounts for 43.6% of the mass of tetraethyl orthosilicate;

[0190] The temperature for the mixing reaction of the oil phase mixture and the aqueous phase mixture is 120 °C, the reaction time is 6 h, and the mass ratio of ammonia water to tetraethyl orthosilicate is 39%;

[0191] Place the microcapsules in a first atmosphere and heat them to a first temperature at a first heating rate and calcine them at the first temperature for 1 h;

[0192] Place the microcapsules treated at the first temperature in a second atmosphere and heat them from the first temperature to a second temperature at a second heating rate and calcine them at the second temperature for 2 h;

[0193] Place the microcapsules treated at the second temperature in a third atmosphere and heat them from the second temperature to a third temperature at a third heating rate and calcine them at the third temperature for 1.5 h;

[0194] Place the microcapsules treated at the third temperature in a fourth atmosphere and heat them from the third temperature to a fourth temperature at a fourth heating rate and calcine them at the fourth temperature for 2 h;

[0195] Among them, the first temperature is 300 °C, the second temperature is 480 °C, the third temperature is 750 °C, and the fourth temperature is 950 °C;

[0196] The first heating rate is 3 °C / min, the second heating rate is 2 °C / min, the third heating rate is 0.5 °C / min, and the fourth heating rate is 1 °C / min;

[0197] The first atmosphere, the second atmosphere, the third atmosphere and the fourth atmosphere are all inert atmospheres, and the inert atmosphere is nitrogen.

[0198] Example 8

[0199] The difference between Example 8 and Example 5 is that:

[0200] The second atmosphere is an oxidizing atmosphere, and the oxidizing atmosphere is a mixture of nitrogen and oxygen, and the mass of oxygen is 1.5% of the mass of the mixture.

[0201] Example 9

[0202] The difference between Example 9 and Example 5 is that:

[0203] The second atmosphere is an oxidizing atmosphere, and the oxidizing atmosphere is a mixture of nitrogen and oxygen, and the mass of oxygen is 4% of the mass of the mixture.

[0204] Comparative Example 1

[0205] The difference between Comparative Example 1 and Example 1 is that FeCl2·4H2O and FeCl3·6H2O are not added.

[0206] Comparative Example 2

[0207] The difference between Comparative Example 2 and Example 2 is that FeCl2·4H2O and FeCl3·6H2O are not added.

[0208] Comparative Example 3

[0209] The difference between Comparative Example 3 and Example 9 is that:

[0210] The first heating rate is 5 °C / min, the second heating rate is 5 °C / min, the third heating rate is 5 °C / min, and the fourth heating rate is 5 °C / min.

[0211] Using the adsorbents in the above Examples 1-9 and Comparative Examples 1-3 for adsorption, before adsorption, the impurity contents in trichlorosilane are: B is 272.3 ppb, P is 359.6 ppb, and the metal impurities are 137.1 ppb. The metal impurities include Fe, Al, and Ca.

[0212] The adsorbent was placed in trichlorosilane at a temperature of 30 °C for 8 h for adsorption. The mass of the adsorbent was 8% of the mass of trichlorosilane. Then, the adsorbent was removed, and the impurity content in trichlorosilane was detected. The specific detection results are shown in Table 1.

[0213] Table 1 Test Results

[0214] Name B / ppb P / ppb Metal Impurity / ppb Example 1 38.2 44.7 13.3 Example 2 43.5 45.9 12.1 Example 3 29.7 36.3 11.3 Example 4 32.2 35.1 9.7 Example 5 22.3 32.7 8.5 Example 6 26.4 31.3 9.1 Example 7 21.6 29.6 8.3 Example 8 14.3 21.5 6.4 Example 9 12.8 20.8 7.0 Comparative Example 1 83.2 103.6 37.6 Comparative Example 2 88.5 111.4 36.1 Comparative Example 3 18.1 23.7 8.1

[0215] As can be seen from Table 1, the adsorbents in the above-mentioned examples can effectively adsorb B, P, and metal impurities in trichlorosilane. The adsorption effect in Examples 5 - 9 is better than that in Examples 1 - 4, indicating that the adsorption performance of the adsorbent can be improved by high-temperature calcination treatment. The adsorption effects in Examples 8 and 9 are relatively good, and the adsorption effect of the adsorbent treated in an oxidizing atmosphere is good. The adsorbent prepared by the method in the present invention can adsorb metal impurities in trichlorosilane and improve the adsorption effect of the adsorbent on impurities in trichlorosilane.

[0216] Example 10

[0217] After the adsorbent in Example 9 adsorbs impurities in trichlorosilane, the adsorbent is regenerated.

[0218] The method for regenerating the adsorbent may include:

[0219] Placing the adsorbent to be regenerated in a vacuum environment at 90°C for 36 h;

[0220] Placing the adsorbent in a vacuum environment at 450°C for 8 h;

[0221] Placing the adsorbent in an oxidizing atmosphere at 240°C for 4 h;

[0222] The oxidizing atmosphere is a mixture of nitrogen and oxygen, and the mass of oxygen is 6% of the mass of the mixture.

[0223] Example 11

[0224] After the adsorbent in Example 9 adsorbs impurities in trichlorosilane, the adsorbent is regenerated.

[0225] The method for regenerating the adsorbent may include:

[0226] Placing the adsorbent to be regenerated in a vacuum environment at 180°C for 4 h;

[0227] Placing the adsorbent in a vacuum environment at 260°C for 24 h;

[0228] Placing the adsorbent in an oxidizing atmosphere at 120°C for 28 h;

[0229] The oxidizing atmosphere is a mixture of nitrogen and oxygen, and the mass of oxygen is 6% of the mass of the mixture.

[0230] Comparative Example 4

[0231] After the adsorbent in Example 9 adsorbs impurities in trichlorosilane, the unregenerated adsorbent.

[0232] The adsorption tests were carried out on the regenerated adsorbents in Examples 10 - 11 and the adsorbent in Comparative Example 4 according to the test method in Example 9 above. The specific results are shown in Table 2.

[0233] Table 2 Test Results

[0234] Name B / ppb P / ppb Metal Impurity / ppb Example 10 57.2 76.9 38.6 Example 11 55.8 74.5 42.1 Comparative Example 4 164.2 203.7 78.8

[0235] As can be seen from Table 2, the above - regenerated adsorbent can adsorb B, P, and metal impurities in trichlorosilane. The adsorption effect of the regenerated adsorbent is good and it can be recycled.

[0236] The embodiments of the present invention have been described above. However, the present invention is not limited to the above - described specific embodiments. The above - described specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims, and all of them fall within the protection scope of the present invention.

Claims

1. A method for preparing an adsorbent, characterized in that, Comprising: Dissolve FeCl2·4H2O and FeCl3·6H2O in a solvent to obtain an aqueous phase mixture; Add a silane precursor to molten paraffin and mix to obtain an oil phase mixture; Mix the oil phase mixture with the aqueous phase mixture and add a basic initiator, and stir and react to obtain microcapsules; the basic initiator includes at least one of ammonia water, urea, ethylenediamine, sodium hydroxide, and potassium hydroxide; Remove the paraffin in the microcapsules to obtain an adsorbent; The step of removing the paraffin in the microcapsules to obtain an adsorbent includes: Soak the microcapsules in a paraffin dissolving agent for 16 - 48 h; Wash the soaked microcapsules and dry them at 60 - 90 °C to obtain an adsorbent; or The step of removing the paraffin in the microcapsules to obtain an adsorbent includes: Place the microcapsules in a first atmosphere and heat them to a first temperature at a first heating rate and calcine them at the first temperature for 0.5 - 1.5 h; Place the microcapsules treated at the first temperature in a second atmosphere and heat them from the first temperature to a second temperature at a second heating rate and calcine them at the second temperature for 1 - 3 h; Place the microcapsules treated at the second temperature in a third atmosphere and heat them from the second temperature to a third temperature at a third heating rate and calcine them at the third temperature for 0.5 - 1.5 h; Place the microcapsules treated at the third temperature in a fourth atmosphere and heat them from the third temperature to a fourth temperature at a fourth heating rate and calcine them at the fourth temperature for 1 - 3 h; Wherein, the first temperature is 280 - 300 °C, the second temperature is 480 - 500 °C, the third temperature is 700 - 750 °C, and the fourth temperature is 820 - 950 °C; The first heating rate is 3 - 6 °C / min, the second heating rate is 1.5 - 2.5 °C / min, the third heating rate is 0.5 - 1 °C / min, and the fourth heating rate is 0.5 - 1 °C / min; The first atmosphere, the second atmosphere, the third atmosphere, and the fourth atmosphere are all inert atmospheres; or The first atmosphere is an inert atmosphere, the second atmosphere is an oxidizing atmosphere, the third atmosphere is an inert atmosphere, and the fourth atmosphere is an inert atmosphere.

2. The preparation method according to claim 1, characterized in that, The molar ratio of FeCl2·4H2O to FeCl3·6H2O is 1:(2 - 2.5); and / or The mass ratio of paraffin to the silane precursor is 10:(1 - 10); and / or The mass of FeCl2·4H2O and FeCl3·6H2O accounts for 3% - 44% of the mass of the silane precursor.

3. The preparation method according to claim 1, characterized in that, The temperature for the mixing reaction of the oil phase mixture and the aqueous phase mixture is 30 - 200 °C; and / or The time for the mixing reaction of the oil phase mixture and the aqueous phase mixture is 2 - 8 h.

4. The preparation method according to claim 1, wherein The mass ratio of the basic initiator to the silane precursor is (2 - 39):

100.

5. The preparation method according to claim 1, characterized in that, The solvent includes water and ethanol.

6. The preparation method according to claim 1, characterized in that, The step of mixing the oil phase mixture with the aqueous phase mixture and adding a basic initiator and stirring and reacting to obtain microcapsules includes: Mix the oil phase mixture with the aqueous phase mixture and add ammonia water and stir and react to obtain a reaction product; The reaction product is washed and dried to obtain microcapsules.

7. The preparation method according to claim 6, characterized in that, The steps of washing and drying the reaction product include: The reaction product is washed with a washing solution, which includes water and ethanol; The washed reaction product is dried at 60-120 °C.

8. The preparation method according to claim 1, characterized in that, After removing the paraffin in the microcapsules, it further includes: Soaking the adsorbent with an alkaline solution and drying it.