Hydrotalcite adsorbent, its preparation method, and application in removing impurities from chlorosilane

Abstract

The present invention provides a hydrotalcite adsorbent, a preparation method thereof, and an application thereof in the purification of chlorosilanes. The preparation method includes: S1 preparing a metal salt solution and a first alkali solution respectively; S2 synthesizing a magnesium-zinc-aluminum hydrotalcite; S3 synthesizing a magnesium-zinc-aluminum composite metal oxide; S4 synthesizing a hydrotalcite adsorbent. In the present invention, a magnesium-zinc-aluminum ternary hydrotalcite is first prepared by the nucleation / crystallization isolation method, and then a hydrated-reduced magnesium-zinc-aluminum hydrotalcite with a large specific surface area, good stability, a wide pH application range, and rich Bronsted basic sites is obtained through a calcination-hydration reduction method. When it is applied to the reaction of chlorosilane adsorption and purification, the effective removal of boron and phosphorus impurities can be achieved. The present invention provides a preparation method of a hydrotalcite adsorbent and expands the application of the hydrotalcite adsorbent in the field of chlorosilanes.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrotalcite adsorbents, and particularly to hydrotalcite adsorbents, their preparation methods, and their applications in the purification of chlorosilanes. Background Art

[0002] The photovoltaic industry is regarded as an important direction for the development of new energy due to its advantages such as wide energy sources, green environmental protection without pollution, safety and sustainability. With the vigorous development of the photovoltaic industry, the installed capacity of photovoltaics continues to increase, posing higher requirements for the production and quality of its raw material, polysilicon. The improved Siemens method is the current mainstream process for producing polysilicon. In this process, the quality of the polysilicon product depends on the quality of the intermediate trichlorosilane. Although most impurities in trichlorosilane can be removed by rectification, due to the similar physical properties of boron-based impurities and trichlorosilane, they cannot be effectively removed by rectification. If boron and phosphorus compounds are controlled to the ppb level, about 55 - 70 theoretical plates of the rectification column are required, resulting in high energy consumption.

[0003] Among the various separation methods reported currently, the adsorption method has the advantages of easy operation, wide application range, and the adsorbent can be reused, and is widely used in industrial production. Commonly used among them include resin adsorbents, but the effective adsorption component of the adsorption and purification resin is the amino group, and the amino group may undergo a disproportionation reaction with chlorosilane during the adsorption process, resulting in a decrease in the purity of chlorosilane and poor purification effect. Therefore, it is of great significance to develop an adsorbent with good adsorption effect, low energy consumption, and low cost. Summary of the Invention

[0004] In view of this, the present invention provides a hydrotalcite adsorbent, its preparation method, and its application in the purification of chlorosilanes. The hydrotalcite adsorbent has the advantages of large specific surface area, good stability, wide pH application range, and rich Bronsted basic sites. When it is applied to the reaction of adsorbing and purifying chlorosilanes, it can effectively remove boron and phosphorus impurities.

[0005] To solve the technical problems proposed in the background art, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a preparation method of a hydrotalcite adsorbent, and the preparation method includes:

[0007] S1: Prepare a metal salt solution and a first alkali solution respectively: The method for preparing the metal salt solution is: dissolve soluble magnesium salt, soluble zinc salt, and soluble aluminum salt in water and disperse them; the method for preparing the first alkali solution is: dissolve an alkaline substance in water and disperse it;

[0008] S2: Synthesize the magnesium zinc aluminum hydrotalcite precursor: Add the metal salt solution and the alkali solution described in S1 into a colloid mill reactor at the same feeding rate, and a white slurry is obtained after the reaction; then perform crystallization treatment on the white slurry to obtain the magnesium zinc aluminum hydrotalcite precursor;

[0009] S3: Synthesize the magnesium zinc aluminum composite metal oxide: Calcinate the magnesium zinc aluminum hydrotalcite obtained in S2, set the heating rate to 2 - 12 °C / min, the temperature to 300 - 700 °C, and hold for 5 - 9 h to obtain the magnesium zinc aluminum composite metal oxide;

[0010] S4: Synthesize the hydrotalcite adsorbent: Dissolve the alkaline substance in water and disperse it to obtain a second alkali solution, place the magnesium zinc aluminum composite metal oxide obtained in S3 into the second alkali solution, and carry out a hydration restoration reaction by stirring at 80 - 120 °C to obtain the hydrotalcite adsorbent.

[0011] According to some embodiments of the present invention, the soluble magnesium salt described in S1 includes at least one of magnesium nitrate, magnesium chloride, and magnesium sulfate, the soluble zinc salt includes at least one of zinc nitrate, zinc chloride, and zinc sulfate, and the soluble aluminum salt includes at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate; the concentration of magnesium ions in the metal salt solution is 0.03 - 0.3 M, the concentration of zinc ions is 0.03 - 0.3 M, and the concentration of aluminum ions is 0.03 - 0.3 M.

[0012] According to some embodiments of the present invention, the alkaline substance includes at least one of sodium hydroxide, potassium hydroxide, sodium bicarbonate, and sodium carbonate.

[0013] According to some embodiments of the present invention, the concentration of the first alkali solution is 0.3 - 4 M; the concentration of the second alkali solution is 0.2 - 2.5 M.

[0014] Further, in S2, set the rotation speed of the colloid mill reactor to 3600 - 6000 rpm, and the reaction time to 5 - 12 min.

[0015] Further, in S2, set the crystallization temperature to 50 - 150 °C, and the crystallization time to 24 - 48 h.

[0016] Further, in S4, set the stirring speed to 500 - 1200 rpm, and the hydration restoration reaction time to 12 - 24 h.

[0017] In a second aspect, the present invention provides a hydrotalcite adsorbent, which is prepared by the above preparation method.

[0018] In a third aspect, the present invention provides the application of the hydrotalcite adsorbent as described above. The hydrotalcite adsorbent is used for removing impurities from chlorosilanes and adsorbing boron, phosphorus and metals in the chlorosilanes.

[0019] Further, the method of the application includes the following steps: taking the hydrotalcite adsorbent and placing it into the liquid-phase chlorosilane to be treated, and performing adsorption treatment by stirring. Set the adsorption temperature to 25-80 °C, the stirring rate to 500-1200 rpm, and the adsorption time to 1-24 h.

[0020] The beneficial effects of the above technical solutions of the present invention are as follows:

[0021] The present invention provides a hydrotalcite adsorbent, a preparation method thereof, and an application in the removal of impurities from chlorosilanes. The preparation method includes: S1 respectively preparing a metal salt solution and a first alkali solution; S2 synthesizing magnesium-zinc-aluminum hydrotalcite; S3 synthesizing magnesium-zinc-aluminum composite metal oxide; S4 synthesizing a hydrotalcite adsorbent.

[0022] In the present invention, a magnesium-zinc-aluminum ternary hydrotalcite is first prepared by the nucleation / crystallization isolation method, and then the grain size of the material is effectively reduced by the calcination-hydration restoration method, and the stability is improved by the interlayer electrostatic attraction. Therefore, a hydrated and restored magnesium-zinc-aluminum hydrotalcite with a large specific surface area, good stability, a wide pH application range, and rich Bronsted basic sites is obtained. When it is applied to the reaction of adsorbing and removing impurities from chlorosilanes, it can effectively remove boron and phosphorus impurities. The present invention provides a preparation method of a hydrotalcite adsorbent and expands the application of the hydrotalcite adsorbent in the field of chlorosilanes. In addition, the preparation method has the advantages of simple process, mild conditions, and low energy consumption, and has broad industrial application potential. Detailed Embodiments

[0023] In order to further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the present invention.

[0024] In a first aspect, the present invention provides a preparation method of a hydrotalcite adsorbent, and the preparation method includes:

[0025] S1: respectively preparing a metal salt solution and a first alkali solution: wherein the method of preparing the metal salt solution is: dissolving soluble magnesium salt, soluble zinc salt and soluble aluminum salt in water and dispersing; the method of preparing the first alkali solution is: dissolving an alkaline substance in water and dispersing;

[0026] S2: Synthesize the magnesium-zinc-aluminum hydrotalcite precursor: Add the metal salt solution and the alkali solution described in S1 into a colloid mill reactor at the same feeding rate, and obtain a white slurry after the reaction; then perform crystallization treatment on the white slurry to obtain the magnesium-zinc-aluminum hydrotalcite precursor;

[0027] S3: Synthesize the magnesium-zinc-aluminum composite metal oxide: Calcinate the magnesium-zinc-aluminum hydrotalcite obtained in S2, set the heating rate to 2 - 12 °C / min, the temperature to 300 - 700 °C, and maintain for 5 - 9 h to obtain the magnesium-zinc-aluminum composite metal oxide;

[0028] S4: Synthesize the hydrotalcite adsorbent: Dissolve the alkaline substance in water and disperse to obtain a second alkali solution, place the magnesium-zinc-aluminum composite metal oxide obtained in S3 in the second alkali solution, and carry out a hydration restoration reaction by stirring at 80 - 120 °C to obtain the hydrotalcite adsorbent.

[0029] According to some embodiments of the present invention, the soluble magnesium salt described in S1 includes at least one of magnesium nitrate, magnesium chloride, and magnesium sulfate, the soluble zinc salt includes at least one of zinc nitrate, zinc chloride, and zinc sulfate, and the soluble aluminum salt includes at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate; the concentration of magnesium ions in the metal salt solution is 0.03 - 3 M, the concentration of zinc ions is 0.03 - 3 M, and the concentration of aluminum ions is 0.03 - 3 M. For example, the soluble magnesium salt can be magnesium nitrate, and the concentration of magnesium ions after dissolving magnesium nitrate in water can be 0.03 M, 0.1 M, 0.5 M, 1 M, 2 M, or 3 M; the soluble zinc salt can be zinc nitrate, and the concentration of zinc ions after dissolving zinc nitrate in water can be 0.03 M, 0.1 M, 0.5 M, 1 M, 2 M, or 3 M; the soluble aluminum salt can be aluminum nitrate, and the concentration of aluminum ions after dissolving aluminum nitrate in water can be 0.03 M, 0.1 M, 0.5 M, 1 M, 2 M, or 3 M. Preferably, the concentration of magnesium ions in the metal salt solution is 0.3 - 1 M, the concentration of zinc ions is 0.3 - 1 M, and the concentration of aluminum ions is 0.3 - 1 M.

[0030] According to some embodiments of the present invention, the molar ratio of magnesium ions: zinc ions: aluminum ions in the metal salt solution is (1 - 3):(1 - 3):(1).

[0031] According to some embodiments of the present invention, in S1, dissolve the soluble magnesium salt, soluble zinc salt, and soluble aluminum salt in water and disperse them, where the water is ultrapure water, and the dispersion method is ultrasonic dispersion.

[0032] According to some embodiments of the present invention, the alkaline substance includes at least one of sodium hydroxide, potassium hydroxide, sodium bicarbonate, and sodium carbonate. Further, the concentration of the first alkaline solution is 0.3 to 4 M; the concentration of the second alkaline solution is 0.2 to 2.5 M. For example, the alkaline substances can be sodium hydroxide and sodium carbonate. Different contents of sodium hydroxide and sodium carbonate are respectively stirred and dissolved in ultrapure water to obtain the first alkaline solution and the second alkaline solution. In the first alkaline solution, the concentration of sodium hydroxide is 0.15 to 2.0 M, and the concentration of sodium carbonate is 0.15 to 2.0 M; in the second alkaline solution, the concentration of sodium hydroxide is 0.1 to 1.25 M, and the concentration of sodium carbonate is 0.1 to 1.25 M.

[0033] According to some embodiments of the present invention, the molar ratio of the metal salt solution to the first alkaline solution is 1.2 to 2.4); the mass ratio of the magnesium-zinc-aluminum composite metal oxide to the second alkaline solution is 1.0 to 2.0.

[0034] According to some embodiments of the present invention, in S2, the rotation speed of the colloid mill reactor is set to 3600 to 6000 rpm, and the reaction time is 5 to 12 min. Preferably, the rotation speed of the colloid mill reactor is 3600 to 4200 rpm, and the reaction time is 5 to 8 min.

[0035] According to some embodiments of the present invention, in S2, the crystallization temperature is set to 50 to 150 °C, and the crystallization time is 24 to 48 h. Preferably, the crystallization temperature is 80 to 120 °C, and the crystallization time is 30 to 48 h.

[0036] According to some embodiments of the present invention, in S4, a hydration restoration reaction is carried out with stirring at 80 to 120 °C. The rotation speed of the stirring is set to 500 to 1200 rpm, and the time of the hydration restoration reaction is 12 to 24 h. Preferably, the temperature of the hydration restoration reaction is 90 to 110 °C, the rotation speed of the stirring is 600 to 800 rpm, and the time of the hydration restoration reaction is 12 to 16 h.

[0037] In a second aspect, the present invention provides a hydrotalcite adsorbent prepared by the above-mentioned preparation method.

[0038] In a third aspect, the present invention provides the application of the hydrotalcite adsorbent as described above. The hydrotalcite adsorbent is applied to the purification of chlorosilane to adsorb boron, phosphorus, and metals in the chlorosilane.

[0039] First, the present invention provides a preparation method of a magnesium-zinc-aluminum hydrotalcite adsorbent, and the preparation method includes: first synthesizing a magnesium-zinc-aluminum hydrotalcite precursor by a nucleation / crystallization isolation method; then calcining the magnesium-zinc-aluminum hydrotalcite precursor to obtain a magnesium-zinc-aluminum composite metal oxide; and finally placing the magnesium-zinc-aluminum composite metal oxide in an alkali solution for hydration restoration treatment to obtain a hydrated and restored hydrotalcite material. Further, the present invention also provides the application of the magnesium-zinc-aluminum hydrotalcite adsorbent in the field of chlorosilane impurity removal. As is well known to those skilled in the art, hydrotalcite (Layered Double Hydroxide, LDHs), also known as layered double metal hydroxide, is a classic anion-intercalated two-dimensional layered material, which is formed by the ordered assembly of a positively charged metal ion layer and an interlayer anion carrying a negative charge. There are many choices for its metal ions and anions, and a wide variety of hydrotalcites can be formed. The application of hydrotalcite as an adsorbent is relatively extensive, but different types of hydrotalcite adsorbents will have different technical effects when used in different fields. In order to make the magnesium-zinc-aluminum hydrotalcite adsorbent have better technical effects in adsorbing impurities such as boron, phosphorus, and metals in chlorosilane, the present invention has continuously optimized the preparation of the magnesium-zinc-aluminum hydrotalcite adsorbent, and the optimization means include: (1) exploring the types of metal ions, and finally selecting a ternary magnesium-zinc-aluminum hydrotalcite; (2) performing hydration restoration treatment with an alkali solution after synthesizing the magnesium-zinc-aluminum composite metal oxide to obtain a hydrated and restored hydrotalcite material; (3) exploring the regulation of the calcination temperature and calcination time.

[0040] According to some embodiments of the present invention, the method of the application includes the following steps: taking the hydrotalcite adsorbent and placing it into the liquid-phase chlorosilane to be treated, and performing adsorption treatment by stirring, setting the adsorption temperature at 25-80°C, the stirring rate at 500-1200 rpm, and the adsorption time at 1-24 h. Preferably, the adsorption temperature is set at 25-50°C, the stirring rate is set at 700-1000 rpm, and the adsorption time is set at 12-24 h. After the adsorption is completed, perform suction filtration treatment and recycle the used adsorbent.

[0041] The following further illustrates the present invention through some specific examples.

[0042] Example 1

[0043] (1) Weigh 17.54 g of magnesium nitrate, 16.27 g of zinc nitrate, and 23.19 g of aluminum nitrate, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Mg 2+ : Zn 2+ : Al 3+= 1:1:1, labeled as the salt solution. Weigh 9.4 g of sodium hydroxide and 13.2 g of sodium carbonate and dissolve them in 150 mL of ultrapure water, stir until completely dissolved, and label it as the first alkali solution. At room temperature, transfer the salt solution and the first alkali solution into a colloid mill reactor at a rate of 20 mL / s, set the reactor rotation speed to 4200 rpm, and after reacting for 5 min, a white slurry is obtained. Place the slurry in a three-necked flask and crystallize and grow it at 130 °C for 36 h. After natural cooling, wash it 8 times with ultrapure water and ethanol, then place it in a vacuum drying oven at 80 °C for 24 h. Finally, fully grind the solid substance to obtain magnesium zinc aluminum hydrotalcite A1;

[0044] (2) Accurately weigh 10.0 g of the magnesium zinc aluminum hydrotalcite synthesized in step (1) and place it in a quartz boat, perform calcination treatment in a muffle furnace, set the heating rate to 10 °C / min, the temperature to 550 °C, keep it at a constant temperature for 7 h, and after natural cooling, obtain magnesium zinc aluminum composite oxide B1.

[0045] (3) Accurately weigh 15 g of sodium carbonate and 9 g of sodium hydroxide, dissolve them in 300 mL of ultrapure water, label it as the second alkali solution, transfer 6.0 g of magnesium zinc aluminum composite oxide to the second alkali solution and stir, set the rotation speed to 1000 rpm, the time to 14 h. After completion, wash it 8 times with ultrapure water and ethanol, then place it in a vacuum drying oven at 80 °C for 24 h to obtain the hydrated and restored magnesium zinc aluminum hydrotalcite C1.

[0046] Example 2

[0047] (1) Weigh 26.52 g of magnesium nitrate, 14.37 g of zinc nitrate, and 16.13 g of aluminum nitrate and dissolve them in 200 mL of ultrapure water, place it in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Mg 2+ : Zn 2+ : Al 3+ = 2:1:1, labeled as the salt solution. Weigh 9.7 g of sodium hydroxide and 14.4 g of sodium carbonate and dissolve them in 150 mL of ultrapure water, stir until completely dissolved, and label it as the first alkali solution. At room temperature, transfer the salt solution and the first alkali solution into a colloid mill reactor at a rate of 20 mL / s, set the reactor rotation speed to 4200 rpm, and after reacting for 5 min, a white slurry is obtained. Place the slurry in a three-necked flask and crystallize and grow it at 100 °C for 48 h. After natural cooling, wash it 8 times with ultrapure water and ethanol, then place it in a vacuum drying oven at 80 °C for 24 h. Finally, fully grind the solid substance to obtain magnesium zinc aluminum hydrotalcite A2;

[0048] (2) Accurately weigh 10.0 g of the magnesium-zinc-aluminum hydrotalcite synthesized in step (1) and place it in a quartz boat. Perform calcination treatment in a muffle furnace. Set the heating rate to 8 °C / min, the temperature to 600 °C, and keep it at a constant temperature for 7 h. After natural cooling, obtain the magnesium-zinc-aluminum composite oxide B2.

[0049] (3) Accurately weigh 15 g of sodium carbonate and 9 g of sodium hydroxide, dissolve them in 300 mL of ultrapure water, and label it as the second alkali solution. Transfer 6.0 g of the magnesium-zinc-aluminum composite oxide to the second alkali solution and stir it. Set the rotation speed to 1000 rpm and the time to 14 h. After completion, wash it 8 times with ultrapure water and ethanol, and then place it in a vacuum drying oven at 80 °C for 24 h to obtain the hydrated and restored magnesium-zinc-aluminum hydrotalcite C2.

[0050] Example 3

[0051] (1) Weigh 12.08 g of magnesium nitrate, 23.17 g of zinc nitrate, and 15.75 g of aluminum nitrate metal salts and dissolve them in 200 mL of ultrapure water. Place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Mg 2+ : Zn 2+ : Al 3+ =1:2:1, and label it as the salt solution. Weigh 9.7 g of sodium hydroxide and 14.4 g of sodium carbonate and dissolve them in 150 mL of ultrapure water, and stir until completely dissolved, and label it as the first alkali solution. At room temperature, transfer the salt solution and the first alkali solution to a colloid mill reactor at a rate of 20 mL / s, set the reactor rotation speed to 4200 rpm, and react for 5 min to obtain a white slurry. Place the slurry in a three-necked flask and crystallize and grow at 150 °C for 30 h. After natural cooling, wash it 8 times with ultrapure water and ethanol, and then place it in a vacuum drying oven at 80 °C for 24 h. Finally, thoroughly grind the solid substance to obtain the magnesium-zinc-aluminum hydrotalcite A3;

[0052] (2) Accurately weigh 10.0 g of the magnesium-zinc-aluminum hydrotalcite synthesized in step (1) and place it in a quartz boat. Perform calcination treatment in a muffle furnace. Set the heating rate to 10 °C / min, the temperature to 700 °C, and keep it at a constant temperature for 5 h. After natural cooling, obtain the magnesium-zinc-aluminum composite oxide B3.

[0053] (3) Accurately weigh 15 g of sodium carbonate and 9 g of sodium hydroxide, dissolve them in 300 mL of ultrapure water, and label it as the second alkali solution. Transfer 6.0 g of the magnesium-zinc-aluminum composite oxide to the second alkali solution and stir it. Set the rotation speed to 1000 rpm and the time to 14 h. After completion, wash it 8 times with ultrapure water and ethanol, and then place it in a vacuum drying oven at 80 °C for 24 h to obtain the hydrated and restored magnesium-zinc-aluminum hydrotalcite C3.

[0054] Example 4

[0055] (1) Weigh 28.13 g of magnesium nitrate, 9.64 g of zinc nitrate, and 12.58 g of aluminum nitrate, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Mg 2+ :Zn 2+ :Al 3+ =3:1:1, mark it as the salt solution. The others are the same as in Example 2, and magnesium-zinc-aluminum hydrotalcite A4 is obtained;

[0056] (2)-(3): The same as in Example 2, and finally the hydrated and restored magnesium-zinc-aluminum hydrotalcite C4 is obtained.

[0057] Example 5

[0058] (1) Weigh 8.72 g of magnesium nitrate, 25.96 g of zinc nitrate, and 13.24 g of metal salts of aluminum nitrate, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Mg 2+ :Zn 2+ :Al 3+ =1:3:1, mark it as the salt solution. The others are the same as in Example 2, and magnesium-zinc-aluminum hydrotalcite A5 is obtained;

[0059] (2)-(3): The same as in Example 2, and finally the hydrated and restored magnesium-zinc-aluminum hydrotalcite C5 is obtained.

[0060] Example 6

[0061] (1) The same as in Example 2;

[0062] (2) Accurately weigh 10.0 g of the magnesium-zinc-aluminum hydrotalcite synthesized in step (1) and place it in a quartz boat, perform calcination treatment in a muffle furnace, set the heating rate to 8 °C / min, the temperature to 350 °C, keep it at a constant temperature for 7 h, and after natural cooling, obtain magnesium-zinc-aluminum composite oxide B6.

[0063] (3): The same as in Example 2, and finally the hydrated and restored magnesium-zinc-aluminum hydrotalcite C6 is obtained.

[0064] Example 7

[0065] (1) The same as in Example 2;

[0066] (2) Accurately weigh 10.0 g of the magnesium-zinc-aluminum hydrotalcite synthesized in step (1) and place it in a quartz boat, perform calcination treatment in a muffle furnace, set the heating rate to 8 °C / min, the temperature to 700 °C, keep it at a constant temperature for 7 h, and after natural cooling, obtain magnesium-zinc-aluminum composite oxide B7.

[0067] (3) The same as in Example 2, and finally the hydrated and restored magnesium-zinc-aluminum hydrotalcite C7 is obtained.

[0068] Comparative Example 1

[0069] (1) Weigh 35.07 g of magnesium nitrate and 24.41 g of aluminum nitrate, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Mg 2+ :Al 3+ = 2:1, mark it as the salt solution. The others are the same as in Example 2, and magnesium-zinc-aluminum hydrotalcite a1 is obtained;

[0070] (2)-(3): The same as in Example 2, and finally the hydrated and restored binary magnesium-aluminum hydrotalcite c1 is obtained.

[0071] Comparative Example 2

[0072] (1) Weigh 36.12 of zinc nitrate and 23.60 of aluminum nitrate, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Zn 2+ :Al 3+ = 2:1, mark it as the salt solution. The others are the same as in Example 2, and magnesium-zinc-aluminum hydrotalcite a2 is obtained;

[0073] (2)-(3): The same as in Example 2, and finally the hydrated and restored binary zinc-aluminum hydrotalcite c2 is obtained.

[0074] Comparative Example 3

[0075] (1) Weigh 20.17 g of calcium nitrate, 11.24 g of zinc nitrate, and 15.51 g of aluminum nitrate, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Ca 2+ :Zn 2+ :Al 3+ = 2:1:1, mark it as the salt solution. The others are the same as in Example 2, and calcium-zinc-aluminum hydrotalcite a3 is obtained;

[0076] (2)-(3): The same as in Example 2, and finally the hydrated and restored calcium-zinc-aluminum hydrotalcite c3 is obtained.

[0077] Comparative Example 4

[0078] (1) Weigh 22.91 g of nickel nitrate, 12.01 g of zinc nitrate, and 14.98 g of aluminum nitrate metal salts, dissolve them in 200 mL of ultrapure water, place them in an ultrasonic machine for dispersion treatment until the metal salts are completely dissolved, and Ni 2+ :Zn 2+ :Al 3+ = 2:1:1, mark it as the salt solution. The others are the same as in Example 2, and nickel-zinc-aluminum hydrotalcite a4 is obtained;

[0079] (2)-(3): The same as in Example 2, and finally the hydrated and restored nickel-zinc-aluminum hydrotalcite c4 is obtained.

[0080] Comparative Example 5

[0081] Compared with Example 2, no hydration restoration treatment was carried out, that is, there was no step (3), and other steps were the same, obtaining the magnesium-zinc-aluminum composite oxide c5.

[0082] Application Example

[0083] The adsorbents prepared in Examples 1-7 and Comparative Examples 1-5 were applied to the purification of chlorosilane. The method for the purification of chlorosilane was as follows:

[0084] 2.0 g of the adsorbents prepared in Examples 1-7 and Comparative Examples 1-5 were respectively taken and placed in 100 mL of liquid-phase chlorosilane. At 25 °C, the stirring rate was set to 800 rpm and the time was 24 h. After stirring, the liquid was filtered by suction, and the used adsorbents were recovered. The impurity contents of the liquid-phase substances before and after adsorption were measured by ICP-OES method. The test data are recorded in Table 1.

[0085] Example 8

[0086] The adsorbent in Example 2 was recovered and then applied to the purification of chlorosilane again. The method for the purification of chlorosilane was the same as that in the Application Example. The impurity contents of the liquid-phase substances before and after adsorption were measured by ICP-OES method. The test data are recorded in Table 1.

[0087] Table 1

[0088]

[0089]

[0090] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the field to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components.

[0091] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. Application of a hydrotalcite adsorbent in adsorbing boron, phosphorus and metals in chlorosilanes, characterized in that, The preparation method of the hydrotalcite adsorbent includes: S1: Prepare a metal salt solution and a first alkali solution respectively: The method for preparing the metal salt solution is to dissolve soluble magnesium salt, soluble zinc salt and soluble aluminum salt in water and disperse them; the method for preparing the first alkali solution is to dissolve an alkaline substance in water and disperse it; S2: Synthesize a magnesium-zinc-aluminum hydrotalcite precursor: Add the metal salt solution and the alkali solution in S1 to a colloid mill reactor at the same feeding rate, and obtain a white slurry after reaction; then perform crystallization treatment on the white slurry to obtain a magnesium-zinc-aluminum hydrotalcite precursor; S3: Synthesize a magnesium-zinc-aluminum composite metal oxide: Calcinate the magnesium-zinc-aluminum hydrotalcite obtained in S2, set the heating rate to 2-12 °C / min, the temperature to 300-700 °C, and hold for 5-9 h to obtain the magnesium-zinc-aluminum composite metal oxide; S4: Synthesize a hydrotalcite adsorbent: Dissolve an alkaline substance in water and disperse it to obtain a second alkali solution, place the magnesium-zinc-aluminum composite metal oxide obtained in S3 in the second alkali solution, and carry out a hydration restoration reaction by stirring at 80-120 °C to obtain a hydrotalcite adsorbent.

2. The application according to claim 1, characterized in that, The soluble magnesium salt in S1 includes at least one of magnesium nitrate, magnesium chloride and magnesium sulfate, the soluble zinc salt includes at least one of zinc nitrate, zinc chloride and zinc sulfate, and the soluble aluminum salt includes at least one of aluminum nitrate, aluminum chloride and aluminum sulfate; The concentration of magnesium ions in the metal salt solution is 0.03-0.3 M, the concentration of zinc ions is 0.03-0.3 M, and the concentration of aluminum ions is 0.03-0.3 M.

3. The application according to claim 1, wherein The alkaline substance includes at least one of sodium hydroxide, potassium hydroxide, sodium bicarbonate and sodium carbonate.

4. The application according to claim 3, wherein The concentration of the first alkali solution is 0.3-4 M; the concentration of the second alkali solution is 0.2-2.5 M.

5. The application according to claim 1, characterized in that In S2, set the rotation speed of the colloid mill reactor to 3600-6000 rpm, and the reaction time to 5-12 min.

6. The application according to claim 1, characterized in that, In S2, set the crystallization temperature to 50-150 °C, and the crystallization time to 24-48 h.

7. The application according to claim 1, wherein In S4, set the stirring speed to 500-1200 rpm, and the hydration restoration reaction time to 12-24 h.

8. The application according to claim 1, characterized in that The application method includes the following steps: Take the hydrotalcite adsorbent and place it into the liquid-phase chlorosilane to be treated, and carry out adsorption treatment by stirring. Set the adsorption temperature to 25-80 °C, the stirring rate to 500-1200 rpm, and the adsorption time to 1-24 h.

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