A method for rectifying antimony trichloride

Abstract

The present application relates to chemical technology field, specifically is a kind of rectification method of antimony trichloride.The rectification method provided by the present application includes the following steps: antimony trichloride crude is sent into rectification process, and low-boiling impurities are extracted in top after full reflux, and light distillate and antimony trichloride product are extracted in turn in side line;The system pressure of the rectification process is 3~10kPa;The top condensation temperature of the rectification process is 80~110 DEG C.The rectification purification of antimony trichloride crude is controlled in specific range in the system pressure of rectification process, the boiling point of antimony trichloride and each chloride is reduced, the energy consumption is reduced, the temperature of the whole rectification system is reduced, the security risk of antimony trichloride leakage due to sealing problem is reduced, and the purity of the extracted antimony trichloride product can be improved.Experiments show that the present application successfully extracts antimony trichloride product with high purity and ultra-low content of various impurity elements at low rectification system temperature.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically a method for the distillation of antimony trichloride. Background Technology

[0002] Antimony trichloride (SbCl3) is an inorganic compound with a melting point of 73°C and a boiling point of 223.5°C. It is a colorless solid at room temperature and pressure, and is hygroscopic. It fumes in air and is extremely corrosive. Antimony trichloride has a wide range of applications, with the reduction of high-purity antimony products using it being a widely used method for producing high-purity antimony. Antimony trichloride is primarily purified by distillation. Due to its high boiling point (223.5°C), it releases highly corrosive hydrogen chloride gas in air, which is extremely corrosive to equipment. This limits the choice of materials for distillation purification equipment; most commonly, quartz, borosilicate glass, or Hastelloy are used. Distillation columns are typically designed with two or three sections connected by flanges. To prevent leakage of antimony trichloride, gaskets are generally required for sealing. However, conventional gaskets or PTFE gaskets have a maximum temperature resistance of no more than 200°C. Using other gaskets either results in poor sealing or is too expensive. Due to the gasket's temperature resistance issues, a large amount of chloride will leak. Antimony trichloride, in particular, is a highly toxic substance, and once a leak occurs, it will pose a significant safety and environmental hazard. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a distillation method for antimony trichloride. The distillation method provided by the present invention can extract antimony trichloride product at a low distillation system temperature, avoid the risk of antimony trichloride leakage at high temperatures, and improve the purity of the extracted antimony trichloride product.

[0004] This invention provides a method for the distillation of antimony trichloride, comprising the following steps:

[0005] The crude antimony trichloride is fed into a distillation process, and after total reflux, low-boiling-point impurities are collected from the top, and light fractions and antimony trichloride products are collected sequentially from the side stream.

[0006] The system pressure of the distillation process is 3–10 kPa;

[0007] The top condensation temperature of the distillation process is 80–110°C.

[0008] The inventors of this application have creatively discovered that, for the distillation purification of crude antimony trichloride, adding negative pressure control to the distillation system keeps the system pressure within a specific range, lowering the boiling points of antimony trichloride and its chlorides, reducing energy consumption, lowering the temperature of the entire distillation system, reducing the safety hazard of antimony trichloride leakage due to sealing issues, and simultaneously improving the purity of the extracted antimony trichloride product. The system pressure of the distillation process described in this invention is 3–10 kPa, and the rate of change of the system pressure does not exceed -0.2–0.2 kPa / min. The purity of the antimony trichloride product described in this invention is above 6N, and the content of As and Bi in the antimony trichloride product is less than 10 ppb.

[0009] This invention first feeds crude antimony trichloride into a distillation process, performing total reflux to collect low-boiling-point impurities at the top. Specifically, after controlling the system pressure of the distillation process to 3-10 kPa, the crude antimony trichloride is fed to the bottom of the distillation process for heating and evaporation. The material obtained from the heating and evaporation is then subjected to total reflux at the top of the distillation process at a condensation temperature of 80-110°C. During this total reflux process, the low-boiling-point impurities in the material obtained from the heating and evaporation are collected as the fore-fraction at the top of the distillation process. More specifically, the distillation process of this invention is carried out in a distillation column. After controlling the system pressure of the distillation column to 3-10 kPa, the crude antimony trichloride is fed to the bottom of the distillation column for heating and distillation. The material obtained from the heating and distillation is then subjected to total reflux at the top of the distillation column at a condensation temperature of 80-110°C. The low-boiling-point impurities in the material obtained from the heating and evaporation are collected as the fore-fraction at the top of the distillation column. The total reflux time described in this invention is 5–10 hours, preferably 8 hours. The bottom heating distillation temperature in the distillation process described in this invention is 130–180°C. The low-boiling-point impurities described in this invention are collected at a condensation temperature of 50–80°C and are collected as a fore-fraction in a fore-fraction collection bottle. Since the low-boiling-point impurities are discharged from the top of the column during distillation, negative pressure distillation is beneficial for the removal of low-boiling-point impurities without affecting high-boiling-point impurities. Therefore, the purity of antimony trichloride is increased, the number of distillation purification steps is reduced, thereby reducing costs and labor intensity.

[0010] This invention involves total reflux to collect low-boiling-point impurities at the top, followed by the sequential collection of light fractions and antimony trichloride product via a side stream. The side stream in this invention refers to a pipeline extending from the side of the column before the top of the distillation column, used to collect a portion of the material from the distillation column; the light fraction mentioned in this invention is also a type of fore-distillate. Specifically, this invention collects the light fraction via a side stream at a reflux ratio of (4-6):1, preferably 5:1; the amount of light fraction collected is 10-20% of the total volume fraction of the crude antimony trichloride product. This invention collects the antimony trichloride product via a side stream at a reflux ratio of (1-3):1; the amount of antimony trichloride product collected is 60-70% of the total volume fraction of the crude antimony trichloride product. After collecting the light fraction and antimony trichloride product via the side stream, the remaining material is treated as a heavy fraction.

[0011] The distillation process of this invention is carried out under a protective gas atmosphere; the protective gas is selected from at least one of nitrogen, helium, neon, or argon. In some embodiments of this invention, the distillation process is carried out under a protective gas atmosphere by introducing nitrogen into the distillation process system to replace air.

[0012] In some embodiments of the present invention, the distillation process described herein is as follows: Figure 1 The distillation apparatus shown is used for this purpose. Figure 1This is a schematic diagram of the apparatus for the antimony trichloride distillation method of the present invention, wherein 1 is a distillation spherical flask; 2 is a PTFE column section; 3 is column 1; 4 is packing; 5 is a baffle; 6 is column 2; 7 is a fractionation valve; 8 is a top condenser; 9 is a side condenser; 10 is a front fraction collection bottle; 11 is a product collection bottle; and 12 is a vacuum system. Specifically, this invention first introduces nitrogen purging control into the distillation process system for 20-30 minutes at a flow rate of 3-5 L / min. Then, after preheating the distillation flask 1 to 70-100°C, crude antimony trichloride is added to the flask 1 until it reaches 2 / 3 of its capacity. The top condensation temperature of the distillation process is controlled by setting the temperature of the top condenser 8, and the condensation temperature of the pre-collected fraction is controlled by setting the temperature of the side condenser 9. The system pressure of the distillation process is controlled by a vacuum pump in the vacuum system, and the rate of change of system pressure is controlled by a vacuum stabilizing device in the vacuum system 12. The temperature of the distillation flask 1 is controlled to the bottom heating distillation temperature of the distillation process through a heating program. The distillation process begins at a certain temperature. When a large amount of reflux liquid appears in the top condenser 8, total reflux is initiated. The total reflux control time is 5–10 hours. After the total reflux is completed, the light fraction and antimony trichloride product are collected. The split ratio is set by the electromagnetic automatic control valve on the fractionation valve 7. The reflux ratio of the collected light fraction is controlled at (4–6):1, and the amount of light fraction removed is 10–20% of the total distillation volume. The reflux ratio of the collected antimony trichloride product is controlled at (1–3):1, and the amount of collected antimony trichloride product is controlled at 60–70% of the total distillation volume. The remaining product is treated as heavy fraction. After the distillation process is completed, the vacuum pump in the vacuum system 12 is turned off, and nitrogen is introduced into the distillation process system. Under nitrogen protection, the system is naturally cooled to 70–100°C at atmospheric pressure.

[0013] This invention provides a method for the distillation of antimony trichloride. The method includes the following steps: feeding crude antimony trichloride into a distillation process, performing total reflux to collect low-boiling-point impurities at the top, and then sequentially collecting light fractions and antimony trichloride product from the side stream; the system pressure of the distillation process is 3–10 kPa; the top condensation temperature of the distillation process is 80–110°C. This distillation method, for the purification of crude antimony trichloride, incorporates negative pressure control in the distillation system, maintaining the system pressure within a specific range. Through a pressure regulating device, the pressure of the entire distillation system is kept stable, lowering the boiling points of antimony trichloride and its chlorides. Under controlled pressure, the boiling point of antimony trichloride is maintained at 130–180°C, reducing energy consumption and lowering the temperature of the entire distillation system. The PTFE gasket maintains equipment sealing, reducing the safety hazard of antimony trichloride leakage due to sealing issues, and also improving the purity of the collected antimony trichloride product. Experiments show that this invention successfully extracts antimony trichloride with high product purity and extremely low content of various impurity elements at low distillation system temperatures. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the apparatus for the antimony trichloride distillation method of the present invention;

[0015] Figure 2 This is a graph evaluating the boiling point of a compound at a certain pressure. Detailed Implementation

[0016] This invention discloses a method for the distillation of antimony trichloride. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0017] This invention adopts Figure 1 The apparatus shown performs the distillation of antimony trichloride according to the following steps:

[0018] 1) Open the air inlet valve on the distillation flask and introduce nitrogen into the distillation system to replace the air. The replacement time is 30 minutes and the flow rate is 3 L / min.

[0019] 2) Close the air inlet valve, turn on the heater power, and preheat the flask to 100℃;

[0020] 3) Open the feed inlet valve and add an appropriate amount of antimony trichloride into the distillation flask through the feed inlet. The amount added should be 2 / 3 of the capacity of the quartz flask. Then close the feed inlet valve.

[0021] 4) Turn on the top condenser and set the top condenser condensing temperature; turn on the side condenser and set the side condenser condensing temperature.

[0022] 5) After the condenser temperature stabilizes, turn on the vacuum pump switch, adjust the vacuum pressure regulator to stabilize the system pressure at ±0.2 kPa / min, set the distillation system pressure, reset the heating program, and start heating and distillation;

[0023] 6) When a large amount of reflux liquid appears in the top condenser of the column, total reflux is started. The total reflux control time is 5 hours. After the total reflux is completed, the split ratio is set by the electromagnetic automatic control valve on the fractionation valve 7, and the light fraction and product are collected according to a certain volume fraction. The remaining product is treated as heavy fraction.

[0024] 7) After distillation, turn off the vacuum pump, open the inlet valve, and fill with nitrogen. Allow the nitrogen to protect the temperature so that it naturally cools down to 80°C at atmospheric pressure.

[0025] Before heating and distilling antimony trichloride, the condensing temperatures of the top condenser and the side condenser are set in step 4) above, and the pressure of the distillation system is adjusted in step 5). In reality, the boiling point of many substances is determined by the degree of molecular association in the liquid. Sometimes, the boiling point corresponding to the pressure selected for vacuum distillation cannot be found in the literature. Therefore, in actual operation, the pressure is often... Figure 2 To estimate the boiling point of a compound at a certain pressure, Figure 2 This is a graph evaluating the boiling point of a compound at a certain pressure. Figure 2 In the diagram, line A represents the boiling point under reduced pressure, line B represents the boiling point under normal pressure, and line C represents the pressure curve. The evaluation method is as follows: take the pressure value (mmHg) on ​​line C, find its boiling point under normal pressure on line B, then connect these two points with a straight line, extend this straight line to intersect line A, and the intersection point represents the approximate boiling point of the substance under that pressure. Similarly, the boiling point under normal pressure and the pressure required for reduced pressure can be estimated in reverse.

[0026] The present invention will be further described below with reference to the embodiments:

[0027] Example 1

[0028] according to Figure 2 As shown, by using a vacuum regulating device to control the system pressure to 2 kPa (15 mmHg), and connecting the reduced pressure with the boiling point of antimony trichloride at atmospheric pressure as described above, the boiling point of antimony trichloride at a reduced pressure of 4 kPa is approximately 130℃. The distillation process is carried out as follows: the temperature of the condenser at the top of the column is controlled at 80℃, and the temperature on the side of the column is controlled at 72℃; the total reflux time is 8 hours; the reflux ratio of the fore-distillate is 5:1, and the fore-distillate is collected at 10% of the distillate volume fraction; the reflux ratio of the product is 2:1, and the product is collected at 75% of the distillate volume fraction, thus obtaining the distilled product.

[0029] Example 2

[0030] according to Figure 2 As shown, by using a vacuum regulating device to control the system pressure to 5 kPa (37.5 mmHg), and connecting the reduced pressure with the boiling point of antimony trichloride at atmospheric pressure as described above, the boiling point of antimony trichloride at a reduced pressure of 5 kPa is approximately 150℃. The distillation process is carried out as follows: the temperature of the condenser at the top of the column is controlled at 90℃, and the temperature on the side of the column is controlled at 72℃; the total reflux time is 8 hours; the reflux ratio of the fore-distillate is 5:1, and the fore-distillate is collected at 10% of the distillate volume fraction; the reflux ratio of the product is 2:1, and the product is collected at 75% of the distillate volume fraction, thus obtaining the distilled product.

[0031] Example 3

[0032] according to Figure 2As shown, by using a vacuum regulating device to control the system pressure to 20 kPa (75 mmHg), and connecting the reduced pressure with the boiling point of antimony trichloride at atmospheric pressure as described above, the boiling point of antimony trichloride at a reduced pressure of 10 kPa is approximately 165℃. The distillation process is carried out as follows: the temperature of the condenser at the top of the column is controlled at 90℃, and the temperature on the side of the column is controlled at 72℃; the total reflux time is 8 hours; the reflux ratio of the fore-distillate is 5:1, and the fore-distillate is collected at 10% of the distillate volume fraction; the reflux ratio of the product is 2:1, and the product is collected at 75% of the distillate volume fraction, thus obtaining the distilled product.

[0033] The test results of the distillation products of Examples 1 to 3 above are shown in Table 1:

[0034] Table 1

[0035]

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for distilling antimony trichloride, characterized in that, Includes the following steps: The crude antimony trichloride is fed into the distillation process, and after total reflux to collect low-boiling-point impurities at the top, light fractions and antimony trichloride products are collected sequentially from the side streams at a reflux ratio of (1~3):1; the side streams refer to the pipelines drawn from the side of the column before the top of the distillation column in the distillation process. The system pressure of the distillation process is 3~10 kPa; The top condensation temperature of the distillation process is 80~110℃; The bottom heating distillation temperature of the distillation process is 130~180℃; The purity of the antimony trichloride product is above 6N, and the content of As and Bi in the antimony trichloride product is less than 10 ppb.

2. The distillation method according to claim 1, characterized in that, The rate of change of the system pressure does not exceed -0.2 to 0.2 kPa / min.

3. The distillation method according to claim 1, characterized in that, The total reflux time is 5-10 hours.

4. The distillation method according to claim 1, characterized in that, Light fractions were collected from the side stream at a reflux ratio of (4~6):

1.

5. The distillation method according to claim 4, characterized in that, The amount of the light fraction extracted is 10-20% of the total volume fraction of the crude antimony trichloride.

6. The distillation method according to claim 1, characterized in that, The extraction rate of the antimony trichloride product is 60-70% of the total volume fraction of the crude antimony trichloride product.

7. The distillation method according to claim 1, characterized in that, The low-boiling-point impurities were extracted at a condensation temperature of 50-80°C.

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