Preparation process of high-purity germanium tetrafluoride and reaction kettle thereof

Abstract

The present application belongs to the technical field of chemical manufacturing, and particularly relates to a reaction kettle for preparing high-purity germanium tetrafluoride. In the present application, 20% F2 / N2 mixed gas is used as the reaction raw material instead of high-purity fluorine gas, which is easy to store and has low transportation difficulty, thereby significantly reducing the production cost. Meanwhile, the 20% F2 / N2 mixed gas can be introduced into the reaction kettle at one time, and the content of fluorine gas in the reaction system can be accurately controlled, which is more conducive to the formation of germanium tetrafluoride than the conventional way of introducing fluorine gas into the reaction kettle in batches. The fluidized bed layer and the heat-conducting oil pipe for heat exchange are arranged below the inside of the reaction kettle, so that the reaction temperature can be controlled without adding water or twice gas injection. The germanium powder feeding port and the fluorine-nitrogen mixed gas inlet of the reaction kettle are arranged separately, so that the germanium powder and the gas form convection, can be fully mixed and uniform, and the product conversion rate is improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical manufacturing technology, and specifically relates to a reaction vessel for the preparation process of high-purity germanium tetrafluoride. Background Technology

[0002] Germanium tetrafluoride is typically synthesized by the direct reaction of metallic germanium with fluorine gas, with the reaction equation: Ge + 2F₂ → GeF₄. Because this reaction generates a large amount of heat and is prone to runaway, current cooling methods include adding a large amount of water during the reaction or adding a diluent gas before the reaction. The first method, adding water, is cumbersome, and subsequent water treatment leads to resource waste. The second method requires two gas injections: one before the reaction and one during the reaction. This is not only cumbersome, but also difficult to control because the fluorine gas is injected later—meaning a continuous supply of fluorine is needed while simultaneously expelling the existing diluent gas from the reaction system. This results in either incomplete reaction of the metallic germanium or waste of fluorine gas.

[0003] In addition, due to the difficulty in safely transporting high-purity fluorine gas and the high cost of storage, fluorine gas must be prepared on-site, but on-site fluorine gas production equipment is also very expensive. Summary of the Invention

[0004] To address the above problems, this invention provides a process for preparing high-purity germanium tetrafluoride, comprising at least the following steps:

[0005] Step 1: Use germanium powder and 20% F2 / N2 mixed gas as reaction raw materials. Set up a fluidized bed at the bottom inside the reactor. Heat exchange oil pipes are arranged around the fluidized bed. The inlet and outlet of the heat exchange oil pipes extend to the outside of the reactor.

[0006] Step 2: Increase the temperature of the fluidized bed reaction section to 200-350℃ and the pressure to 0.01-0.5MPa;

[0007] Step 3: Add germanium powder from the top of the fluidized bed into the reactor within 10 minutes, and introduce 20% F2 / N2 mixed gas into the reactor from the bottom in one go within 40 minutes; during the raw material reaction, cool down by increasing the flow rate in the heat transfer oil pipe, maintain the pressure of the fluidized bed reaction section at 0.01-1 MPa, and maintain the temperature of the fluidized bed reaction section at 200-400℃;

[0008] Step 4: The generated GeF4 and unreacted N2 mixture is introduced from the outlet of the reactor into the distillation column, where the packing material is a molecular sieve.

[0009] Step 5: The purified GeF4 is condensed and collected in a finished product tank at -50℃ to 100℃.

[0010] Furthermore, the germanium powder in step 1 has a purity of 99.9%, and the F2 in the 20% F2 / N2 mixed gas has a purity of 99% before mixing.

[0011] Furthermore, in step 3, germanium powder is added to the reactor in batches of 5 kg.

[0012] Furthermore, the mass of the 20% F2 / N2 mixed gas introduced into the reactor in step 3 is 4.2 times the mass of the germanium powder.

[0013] Furthermore, the purification in step 5 includes removing light component impurities that do not participate in the reaction from the top of the distillation column and removing heavy component impurities from the bottom of the distillation column, wherein the light component impurities include at least N2.

[0014] A reaction vessel specifically designed for the preparation process described in claim 1, characterized in that: a solid recovery device and a discharge port are provided at the top of the reaction vessel, a germanium powder feeding port is provided in the middle of the reaction vessel, and a fluorine-nitrogen mixed gas inlet is provided at the bottom of the reaction vessel; the diameter of the solid recovery device is larger than the diameter of the fluidized bed; a fluidized bed is provided at the bottom inside the reaction vessel, and heat-conducting oil pipes for heat exchange are provided around the fluidized bed, with the inlet and outlet of the heat-conducting oil pipes extending to the outside of the reaction vessel.

[0015] Furthermore, the germanium powder feeding port is an airtight screw feeder.

[0016] Furthermore, the solids recovery unit uses a cyclone separator.

[0017] Moreover, the heat transfer oil pipe contains heat transfer oil at a constant temperature.

[0018] Compared with existing technologies, the beneficial effects of this technical solution are as follows:

[0019] 1. The reaction raw materials use a 20% F2 / N2 mixed gas instead of high-purity fluorine gas. 20% F2 / N2 mixed gas is a common industrial product with a stable market supply, easy transportation and storage, which significantly reduces production costs. At the same time, nitrogen gas dilutes the fluorine gas, which can both remove the heat of reaction and dilute the concentration of fluorine gas, control the reaction rate and reduce the difficulty of the process. In addition, the use of 20% F2 / N2 mixed gas also avoids the use of high-purity fluorine gas raw materials in traditional technologies, avoiding the problems of difficult safe transportation, high storage costs or high on-site preparation costs associated with high-purity fluorine gas.

[0020] 2. A fluidized bed is installed at the bottom inside the reactor, and heat-conducting oil pipes are installed around the fluidized bed for heat exchange. The temperature of the heat-conducting oil is kept constant between 200 and 400°C. It plays a role in heating up the fluidized bed and preheating the germanium powder to the reaction temperature to initiate the reaction. When the raw material reaction begins to proceed rapidly and generates a large amount of heat, part of the heat is carried away by the relatively low-temperature heat-conducting oil, and another part of the heat is carried away by the nitrogen gas remaining from the reaction of the F2 / N2 mixed gas from the outlet. This solves the problem of existing technologies that require adding a large amount of water for cooling or require two gas injections.

[0021] 3. The germanium powder feeding port and the fluorine / nitrogen mixed gas inlet of the reactor are set separately. The F2 / N2 mixed gas enters from the bottom and the germanium powder enters from the top. The powder and gas form convection, which can be fully and evenly mixed. At the same time, the small diameter of the fluorine / nitrogen mixed gas inlet and the fluidized bed can increase the flow rate of the fluorine gas, so that the germanium powder plays a "boiling" role in the bed, which makes the fluorine gas and germanium powder more fully contacted and further improves the conversion rate.

[0022] 4. The fluidized bed discharge is equipped with a solid recovery device. The solid recovery device adopts a cyclone separator with a diameter larger than that of the fluorine-nitrogen mixed gas inlet and the fluidized bed layer. This allows the germanium powder that has not reacted and has entered the solid recovery device to fall back into the fluidized bed layer, further improving the utilization rate of germanium powder.

[0023] 5. The purification process was changed from distillation to adsorption, and the packing material in the distillation column was replaced with molecular sieves with high adsorption capacity. This not only made the purification effect better than that of distillation, but also reduced the purification process cost. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the reactor structure according to an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of a comparative reaction vessel structure;

[0026] Explanation of reference numerals in the attached diagram: 1. Fluorine-nitrogen mixed gas inlet; 2. Heat transfer oil inlet; 3. Heat transfer oil outlet; 4. Germanium powder feeding port; 5. Fluidized bed; 6. Bed shell; 7. Solid recovery device; 8. Discharge port; 101. Gas inlet; 102. Product gas outlet; 103. Solid inlet; 104. Temperature probe; 105. Baffle; 106. Reactor base. Detailed Implementation

[0027] Example:

[0028] The structure of the reactor is as follows Figure 1As shown, the top of the reactor is equipped with a solid recovery device 7 and a discharge port 8, the middle of the reactor is equipped with a germanium powder feeding port 4, and the bottom of the reactor is equipped with a fluorine-nitrogen mixed gas inlet 1; a fluidized bed 5 is set inside the reactor at the bottom, and heat-conducting oil pipes for heat exchange are set around the fluidized bed, with the heat-conducting oil inlet 2 and the heat-conducting oil outlet 3 both extending to the outside of the reactor.

[0029] The temperature of the fluidized bed reaction section is raised to 200–350℃ and the pressure to 0.01–0.5 MPa. 5 kg of germanium powder is added to the fluidized bed 5 through the germanium powder inlet 4 using a closed screw feeder over 8 minutes. Then, 21 kg of a 20% F2 / N2 mixed gas is introduced through the fluorine-nitrogen mixed gas inlet 1 over 35 minutes. As the temperature rises, the flow rate of the heat transfer oil is increased to cool the bed. The pressure of the fluidized bed reaction section is maintained at 0.01–1 MPa, and the temperature is maintained at 200–400℃. Between ℃, a 20% F2 / N2 mixture is introduced into the fluidized bed and rapidly reacts with the falling germanium powder to form germanium tetrafluoride. The germanium tetrafluoride and N2 mixture exiting the fluidized bed enter the distillation column through outlet 8 for distillation. The light component impurities that do not participate in the reaction are then discharged from the top of the distillation column, while the heavy component impurities are discharged from the bottom of the distillation column. The final product, germanium tetrafluoride, is condensed and collected in a product tank at -50℃ to 100℃. A total of 10.19 kg of the product was collected, with a germanium tetrafluoride conversion rate of approximately 99.5% and a germanium tetrafluoride purity of 99.999%.

[0030] Comparative example:

[0031] The reactor structure used in existing technologies, such as Figure 2 As shown, the reactor includes a gas inlet 101 for injecting fluorine gas, a solid inlet 103 for adding germanium powder, a product gas outlet 102, a temperature probe 104, a baffle 105, and a reactor base 106. Because the fluorine gas and germanium powder react at the bottom of the reactor, not only is it difficult for all the accumulated germanium powder to react, but temperature control also requires adding water or injecting gas twice. This results in a cumbersome process, waste of water resources, difficulty in controlling the amount of fluorine gas during the two gas injections, and the risk of either incomplete reaction of the metallic germanium or waste of fluorine gas. Using this reactor structure, under the same conditions as the example (temperature 200–400°C, pressure 0.01–1 MPa, reactants being 5 kg of germanium powder and 21 kg of 20% F2 / N2 mixed gas), reaction time, and product condensation and collection), only 8.5 kg of germanium tetrafluoride was ultimately collected, with a germanium tetrafluoride conversion rate of only 83%.

[0032] In summary, the beneficial effects of this method and the reactor structure are as follows:

[0033] 1. The reaction raw materials use a 20% F2 / N2 mixed gas instead of high-purity fluorine gas. 20% F2 / N2 mixed gas is a common industrial product with a stable market supply, easy transportation and storage, which significantly reduces production costs. At the same time, nitrogen gas dilutes the fluorine gas, which can both remove the heat of reaction and dilute the concentration of fluorine gas, control the reaction rate and reduce the difficulty of the process. In addition, the use of 20% F2 / N2 mixed gas also avoids the use of high-purity fluorine gas raw materials in traditional technologies, avoiding the problems of difficult safe transportation, high storage costs or high on-site preparation costs associated with high-purity fluorine gas.

[0034] 2. A fluidized bed is installed at the bottom inside the reactor, and heat-conducting oil pipes are installed around the fluidized bed for heat exchange. The temperature of the heat-conducting oil is kept constant between 200 and 400°C. It plays a role in heating up the fluidized bed and preheating the germanium powder to the reaction temperature to initiate the reaction. When the raw material reaction begins to proceed rapidly and generates a large amount of heat, part of the heat is carried away by the relatively low-temperature heat-conducting oil, and another part of the heat is carried away by the nitrogen gas remaining from the reaction of the F2 / N2 mixed gas from the outlet. This solves the problem of existing technologies that require adding a large amount of water for cooling or require two gas injections.

[0035] 3. The germanium powder feeding port and the fluorine / nitrogen mixed gas inlet of the reactor are set separately. The F2 / N2 mixed gas enters from the bottom and the germanium powder enters from the top. The powder and gas form convection, which can be fully and evenly mixed. At the same time, the small diameter of the fluorine / nitrogen mixed gas inlet and the fluidized bed can increase the flow rate of the fluorine gas, so that the germanium powder plays a "boiling" role in the bed, which makes the fluorine gas and germanium powder more fully contacted and further improves the conversion rate.

[0036] 4. The fluidized bed discharge is equipped with a solid recovery device. The solid recovery device adopts a cyclone separator with a diameter larger than that of the fluorine-nitrogen mixed gas inlet and the fluidized bed layer. This allows the germanium powder that has not reacted and has entered the solid recovery device to fall back into the fluidized bed layer, further improving the utilization rate of germanium powder.

[0037] 5. The purification process was changed from distillation to adsorption, and the packing material in the distillation column was replaced with molecular sieves with high adsorption capacity. This not only made the purification effect better than that of distillation, but also reduced the purification process cost.

Claims

1. A process for preparing high-purity germanium tetrafluoride, characterized in that, At least the following steps are included: Step 1: Use germanium powder and 20% F2 / N2 mixed gas as reaction raw materials, wherein the purity of germanium powder is 99.9% and the purity of F2 in 20% F2 / N2 mixed gas is 99% before mixing; set up a fluidized bed at the bottom inside the reactor, and heat exchange oil pipes are arranged around the fluidized bed, with the inlet and outlet of the heat exchange oil pipes extending to the outside of the reactor. Step 2: The temperature of the reaction section of the fluidized bed is raised to 200-350℃ and the pressure is 0.01-0.5MPa by the heat transfer oil in the heat transfer oil pipe; Step 3: Add germanium powder from the top of the fluidized bed into the reactor within 10 minutes. Within 40 minutes, introduce a 20% F2 / N2 mixed gas into the reactor from the bottom in one go, and the mass of the 20% F2 / N2 mixed gas introduced into the reactor in one go is 4.2 times the mass of the germanium powder. During the raw material reaction, the temperature is reduced by increasing the flow rate of the heat transfer oil in the heat transfer oil pipe, maintaining the pressure of the reaction section of the fluidized bed at 0.01-1 MPa and the temperature of the reaction section of the fluidized bed at 200-400℃. Step 4: The generated GeF4 and unreacted N2 mixture is introduced from the outlet of the reactor into the distillation column, where the packing material is a molecular sieve. Step 5: The purified GeF4 is condensed and collected in a finished product tank at -50℃ to 100℃.

2. The preparation process of high-purity germanium tetrafluoride according to claim 1, characterized in that: In step 3, germanium powder is added to the reactor at a rate of 5 kg per batch.

3. The preparation process of high-purity germanium tetrafluoride according to claim 1, characterized in that: Purification in step 5 includes removing light component impurities that do not participate in the reaction from the top of the distillation column and removing heavy component impurities from the bottom of the distillation column, wherein the light component impurities include at least N2.

4. A reaction vessel specifically used in the preparation process described in claim 1, characterized in that: The top of the reactor is equipped with a solid recovery device and a discharge port, the middle of the reactor is equipped with a germanium powder feeding port, and the bottom of the reactor is equipped with a fluorine-nitrogen mixed gas inlet. The diameter of the solid recovery device is larger than the diameter of the fluidized bed. A fluidized bed is set inside the reactor at the bottom, and heat-conducting oil pipes are arranged around the fluidized bed for heat exchange. The inlet and outlet of the heat-conducting oil pipes extend to the outside of the reactor.

5. The reaction vessel according to claim 4, characterized in that: The germanium powder feeding port is an airtight screw feeder.

6. The reaction vessel according to claim 4, characterized in that: The solids recovery unit uses a cyclone separator.

7. The reaction vessel according to claim 4, characterized in that: The heat transfer oil pipe contains heat transfer oil at a constant temperature.

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