A method and device for hydrolyzing germanium tetrachloride to prepare nano germanium dioxide by using an in-vitro focusing jet microreactor

Abstract

The application discloses a method and device for hydrolyzing germanium tetrachloride to prepare nano germanium dioxide in an in-vitro focusing jet micro-reactor, which comprises the following steps: preparing germanium tetrachloride into a solution or directly using pure liquid germanium tetrachloride; using ultrapure water or ultrapure water containing a dispersing agent as a hydrolysis agent; spraying the germanium tetrachloride and the hydrolysis agent into a closed reaction cavity in the form of a jet through nozzles, and making the two meet and collide at a focusing point in the cavity to generate nano germanium dioxide through a rapid hydrolysis reaction; simultaneously with the reaction, vacuum pumping is performed on the closed reaction cavity to immediately remove hydrogen chloride gas and volatile solvent vapor generated by the hydrolysis from the cavity and condense and recover the hydrogen chloride gas and the volatile solvent vapor through a condenser; and collecting nano germanium dioxide powder generated by the reaction, washing and drying the nano germanium dioxide powder to obtain a product. The application realizes continuous and high-yield preparation of germanium dioxide, the total content of metal impurities in the product is less than 10 ppm, hydrochloric acid and an organic solvent can be recycled and utilized, the application is green and environment-friendly, and the application is easy to be industrialized and enlarged.

Description

Technical Field

[0001] This invention relates to the field of rapeseed treatment technology, and in particular to a method and apparatus for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focusing jet microreactor. Background Technology

[0002] A key problem arises in the hydrolysis of germanium tetrachloride to prepare nano-germanium dioxide: the hydrolysis byproduct hydrochloric acid accumulates continuously in the reaction system, causing a sharp drop in the pH of the suspension. In a strongly acidic environment, the newly formed nano-germanium dioxide undergoes significant back-dissolution, causing the already formed nanoparticles to be corroded and dissolved, resulting in smaller particle size but reduced yield, or dissolving and then re-precipitating, leading to particle coarsening and difficulty in controlling morphology.

[0003] In traditional stirred tank reactors, hydrochloric acid dissolved in water cannot be removed, a problem that is particularly prominent. The applicant's previously proposed microchannel reactor solution addresses corrosion and impurity issues through PEEK or ceramic materials and achieves preliminary particle size control through forced mixing. However, even within the closed microchannels, hydrochloric acid cannot be removed immediately and continues to accumulate in the reaction section and collection liquid, affecting product stability and yield.

[0004] Therefore, to solve the problems of reverse dissolution, particle coarsening, and low yield caused by the accumulation of by-product hydrochloric acid during the traditional hydrolysis process, providing a method and device that can instantly separate the by-product HCl gas during the hydrolysis reaction to prevent it from dissolving in the water and forming high-concentration hydrochloric acid is the key to breaking through the bottleneck of nano-germanium dioxide preparation technology. Summary of the Invention

[0005] In view of this, the present invention provides a method and apparatus for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focusing jet microreactor. In this invention, a germanium tetrachloride solution and ultrapure water are injected into a sealed reaction chamber through a nozzle in the form of jets. Multiple jets converge and collide at the focal point within the chamber, achieving microsecond-level ultrafast mixing and hydrolysis. Simultaneously, a vacuum system continuously evacuates the chamber, immediately removing and condensing the hydrogen chloride gas generated during hydrolysis into concentrated hydrochloric acid, effectively maintaining a low hydrogen chloride partial pressure within the chamber and fundamentally inhibiting germanium dioxide back-dissolution and abnormal particle growth. The reaction products are collected, washed, and dried to obtain high-purity nano-germanium dioxide powder with an average particle size of 1-80 nm, narrow particle size distribution, and good sphericity.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride using an in vitro focused jet microreactor includes the following steps:

[0008] (1) Prepare germanium tetrachloride into a solution or use pure liquid germanium tetrachloride directly;

[0009] (2) Use ultrapure water or ultrapure water containing dispersant as the hydrolysate;

[0010] (3) The germanium tetrachloride and the hydrolysant are respectively sprayed into the closed reaction chamber through the nozzle in the form of jets, and they collide at a focal point in the chamber to carry out a rapid hydrolysis reaction to generate nano germanium dioxide.

[0011] (4) While the reaction is in progress, the sealed reaction chamber is evacuated to immediately remove the hydrogen chloride gas and volatile solvent vapor generated by hydrolysis from the chamber and condense and recover them through a condenser.

[0012] (5) Collect the nano-germanium dioxide powder generated by the reaction, and obtain the product after washing and drying.

[0013] Preferably, in step (3), the jet jetting method is any one of two-jet collision focusing, multi-jet confocal focusing, or coaxial annular jet focusing.

[0014] Preferably, in step (3), the nozzle outlet inner diameter is 0.1-2 mm and the flow rate is 1-20 m / s; by adjusting the pump pressure and nozzle size to control the jet velocity, ultrafast mixing at the microsecond to millisecond level can be achieved.

[0015] Preferably, in step (4), the material of the sealed reaction chamber is selected from any one of PEEK polyether ether ketone, polytetrafluoroethylene, alumina ceramic, silicon carbide ceramic or high-purity quartz glass; to ensure corrosion resistance and to prevent the introduction of metallic impurities;

[0016] Preferably, in step (4), the vacuum pumping maintains the absolute pressure inside the cavity at 10 kPa-100 kPa; the vacuum pumping rate is adjusted according to the HCl generation rate to ensure that the partial pressure of HCl inside the cavity is always below the critical value for germanium dioxide re-dissolution. The extracted HCl gas is condensed in a -10~5 ℃ condenser and directly recovered as reusable concentrated hydrochloric acid, and the organic solvent is also recovered through subsequent condensation and separation.

[0017] Preferably, in step (4), pure germanium tetrachloride is used for hydrolysis, and the volume ratio of germanium tetrachloride to water is 1:2-1:10;

[0018] Alternatively, the concentration of the germanium tetrachloride solution can be 0.05~2.0 mol / L, and the solvent can be any one of ethanol, isopropanol, acetone, acetonitrile or tetrahydrofuran; PVP, PEG or other dispersants can be selectively added to the hydrolysate at a mass concentration of 0~3%.

[0019] Preferably, in step (4), the temperature inside the reaction chamber is controlled at 20~80℃.

[0020] Preferably, in step (5), the drying is vacuum freeze drying or vacuum drying at a temperature below 80°C.

[0021] Preferably, in step (5), the purity of germanium dioxide is above 99.99%, and the D50 particle size is 10-200nm.

[0022] An apparatus for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride using an in vitro focused jet microreactor includes: a 3D-printed microreactor, a negative pressure chamber, and a product collection and post-processing unit.

[0023] The 3D printed microreactor is made of corundum / zirconia / PEEK and is equipped with at least one germanium tetrachloride nozzle and at least one hydrolysate nozzle. The nozzle spraying directions converge at the same focal point inside the reactor.

[0024] It is also equipped with a raw material delivery pump that is connected to the nozzle respectively, for accurately delivering germanium tetrachloride and deionized water;

[0025] The negative pressure chamber has a vacuum extraction port on its wall, which is connected to a condenser, a gas-liquid separator and a vacuum pump in sequence through pipes, and is used to remove the HCl gas and reaction heat vapor generated in the reaction.

[0026] The product collection and post-processing unit, located downstream of the cavity, includes a filtration, washing, and drying module for collecting slurry containing nano-germanium dioxide and preparing nano-germanium dioxide products with narrow particle size distribution, while simultaneously separating dilute hydrochloric acid waste liquid.

[0027] The present invention achieves the following technical effects compared to the prior art:

[0028] (1) Instant separation of HCl to suppress back dissolution: The present invention uses vacuum suction to remove the HCl gas generated by hydrolysis from the reaction zone at the moment of generation, which effectively avoids the accumulation of high concentration hydrochloric acid in the liquid phase, fundamentally solving the problems of germanium dioxide back dissolution and particle coarsening, resulting in high product yield and stable particle size morphology.

[0029] (2) Ultrafast mixing, uniform and controllable particle size: The in vitro focusing jet of the present invention realizes the violent collision mixing of reactants in a very small spatial scale. The mixing time is much shorter than the nucleation induction time, ensuring that the nucleation process is highly uniform, the product particle size distribution is narrow, and the average particle size can be controlled in the range of 1-80 nm.

[0030] (3) Pure materials and high product purity: The reaction chamber and nozzle of this invention are made of non-metallic corrosion-resistant materials, with no metal impurities leaching out. Combined with high-purity raw materials, the product purity can reach more than 99.99%.

[0031] (4) Resource recycling and green environmental protection: The by-product HCl gas of this invention is efficiently condensed and recovered into concentrated hydrochloric acid, which can be returned to the front-end chlorination distillation process for recycling; organic solvents are also recovered, reducing emissions.

[0032] (5) Continuous production, easy to scale up: The entire process of this invention involves continuous feeding and continuous discharging, and the process parameters are precisely controllable, making it suitable for industrial scale-up. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the device connection for preparing nano-GeO2 using the in vitro focusing jet microreactor of the present invention;

[0034] Figure 2 This is a flowchart of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention discloses a method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride using an in vitro focusing jet microreactor, comprising the following steps:

[0037] (1) Prepare germanium tetrachloride into a solution or use pure liquid germanium tetrachloride directly;

[0038] (2) Use ultrapure water or ultrapure water containing dispersant as the hydrolysate;

[0039] (3) The germanium tetrachloride and the hydrolysant are respectively sprayed into the closed reaction chamber through the nozzle in the form of jets, and they collide at a focal point in the chamber to carry out a rapid hydrolysis reaction to generate nano germanium dioxide.

[0040] (4) While the reaction is in progress, the sealed reaction chamber is evacuated to immediately remove the hydrogen chloride gas and volatile solvent vapor generated by hydrolysis from the chamber and condense and recover them through a condenser.

[0041] (5) Collect the nano-germanium dioxide powder generated by the reaction, and obtain the product after washing and drying.

[0042] In step (3), the jet jetting method is any one of two-jet collision focusing, multi-jet confocal focusing, or coaxial ring tube jet focusing.

[0043] Two jets collide and focus: The GeCl4 solution nozzle and the ultrapure water nozzle are set opposite each other, and the two jets collide and mix at the center of the cavity;

[0044] Multi-jet confocaling: A GeCl4 solution nozzle is centered, and multiple ultrapure water nozzles are arranged around it in a circumferential manner, with all jets converging on the same spatial point;

[0045] Coaxial annular jet focusing: GeCl4 solution is ejected from the inner tube, and ultrapure water is ejected from the outer annular gap, forming a focusing mixing zone outside the tube opening.

[0046] In step (3), the nozzle outlet inner diameter is 0.1-2 mm and the flow velocity is 1-20 m / s.

[0047] In step (4), the material of the sealed reaction chamber is selected from any one of PEEK polyether ether ketone, polytetrafluoroethylene, alumina ceramic, silicon carbide ceramic or high-purity quartz glass.

[0048] In step (4), vacuum pumping is used to maintain the absolute pressure inside the cavity at 10 kPa-100 kPa.

[0049] In step (4), pure germanium tetrachloride is used for hydrolysis, and the volume ratio of germanium tetrachloride to water is 1:2-1:10;

[0050] Alternatively, the concentration of the germanium tetrachloride solution can be 0.05~2.0 mol / L, and the solvent can be any one of ethanol, isopropanol, acetone, acetonitrile, or tetrahydrofuran.

[0051] In step (4), the temperature inside the reaction chamber is controlled at 20~80℃.

[0052] In step (5), the drying is vacuum freeze drying or vacuum drying at a temperature below 80°C.

[0053] In step (5), the purity of germanium dioxide is above 99.99%, and the D50 particle size is 10-200 nm.

[0054] This invention also discloses an apparatus for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride using an in vitro focusing jet microreactor, comprising: a 3D-printed microreactor, a negative pressure chamber, and a product collection and post-processing unit.

[0055] The 3D-printed microreactor is made of corundum / zirconia / PEEK and is equipped with at least one germanium tetrachloride nozzle and at least one hydrolysate nozzle. The nozzle spraying directions converge at the same focal point inside the reactor.

[0056] It is also equipped with a raw material delivery pump connected to the nozzle for precise delivery of germanium tetrachloride and deionized water;

[0057] The negative pressure chamber has a vacuum extraction port on its wall, which is connected to the condenser, gas-liquid separator and vacuum pump in sequence through pipes, and is used to remove the HCl gas and reaction heat vapor generated in the reaction.

[0058] The product collection and post-processing unit, located downstream of the cavity, includes a filtration, washing, and drying module. It is used to collect slurry containing nano-germanium dioxide and prepare nano-germanium dioxide products with narrow particle size distribution, while separating dilute hydrochloric acid waste liquid.

[0059] Example 1: Coaxial annular tube injection + vacuum suction

[0060] use Figure 1 The device shown.

[0061] The sealed cavity is made of PTFE and has an inner diameter of 150 mm.

[0062] The nozzle has a coaxial ring tube structure: the inner diameter of the central tube is 0.3 mm, which is the channel for GeCl4 solution;

[0063] The outer annular gap has a width of 0.2 mm and serves as an ultrapure water channel.

[0064] 6N purity GeCl4 was used, with ultrapure water as the hydrolysis agent. The GeCl4 solution was sprayed from the central tube at a flow rate of 30 mL / min, and the ultrapure water was sprayed from the annulus at a flow rate of 180 mL / min. The two jets were focused and mixed at a distance of about 2 mm outside the tube opening.

[0065] The volume ratio of germanium tetrachloride to water is 1:6;

[0066] The cavity is evacuated by a vacuum pump to maintain an absolute pressure of about 30 kPa. The extracted gas is then condensed at 2 °C to recover hydrochloric acid and ethanol.

[0067] The temperature inside the cavity is controlled at 25 ℃ by a thermostatic jacket;

[0068] The generated powder falls with the liquid droplets into the conical collector at the bottom of the chamber. After solid-liquid separation, it is washed with ultrapure water until Cl is removed. - Freeze-dried at -50 ℃.

[0069] The obtained powder has a D50 of approximately 35 nm, good sphericity, and a particle size range of 20–55 nm, with a yield (based on Ge) of approximately 96%. ICP-MS analysis showed a total metal impurity content of <5 ppm. The recovered hydrochloric acid concentration was approximately 15 wt%, which can be recycled.

[0070] In the comparative example, under the same vacuum suction conditions, the pH of the suspension obtained in the chamber was less than 1 due to the accumulation of hydrochloric acid in the liquid, the product yield was only about 78%, and the D50 was about 120 nm, which is significantly larger than expected.

[0071] Example 2: Multi-stream confocal jet

[0072] The cavity is made of high-purity quartz glass, which facilitates observation of the focal point.

[0073] A GeCl4 solution nozzle (0.2 mm inner diameter) is centered, and six ultrapure water nozzles (0.15 mm inner diameter) are evenly distributed around it, with the spray direction converging 5 mm in front of the center point.

[0074] GeCl4 was dissolved in acetone to prepare a 0.1 mol / L solution, with a total flow rate of 4 mL / min and a total flow rate of 20 mL / min for ultrapure water.

[0075] The molar ratio of germanium tetrachloride to water is 1:4.

[0076] The chamber pressure was maintained at 20 kPa, and vacuum pumping was used in conjunction with -5 ℃ condensation. The reaction temperature was 15 ℃.

[0077] The product was centrifuged, washed with water, and vacuum dried at 80 °C. The D50 was approximately 18 nm, indicating a very uniform product.

[0078] TEM showed that the particles were extremely monodisperse.

[0079] Example 3: Collision Focusing + Dispersant Assistance

[0080] The two nozzles are spaced 10 mm apart and each has an inner diameter of 0.5 mm.

[0081] Spray 0.5 mol / L GeCl4 isopropanol solution onto the left side at a flow rate of 2 mL / min;

[0082] Ultrapure water containing 1% PVP was sprayed into the right side at a flow rate of 8 mL / min.

[0083] The molar ratio of germanium tetrachloride to water is 1:8.

[0084] The chamber is made of alumina ceramic, with a pressure of 40 kPa, and the evacuation and condensation are the same as above. The reaction temperature is 40 ℃.

[0085] The product has a D50 of approximately 50 nm. The addition of PVP further improved the dispersibility before subsequent water washing. After freeze-drying, it is a loose powder without hard agglomeration.

[0086] Example 4: Solvent-free, pure GeCl4 droplet jetting

[0087] This is a more extreme solution, in which pure liquid GeCl4 (anhydrous and solvent-free) is sprayed into the cavity at an extremely low flow rate of 0.2 mL / min through a nozzle with an inner diameter of 0.1 mm, while multiple streams of high-pressure ultrapure water are focused and sprayed from the circumference, with a total water flow rate of 30 mL / min.

[0088] The molar ratio of germanium tetrachloride to water is 1:5.

[0089] The absolute pressure in the chamber is maintained at 10 kPa, and HCl and excess water vapor are forcefully removed.

[0090] Because GeCl4 hydrolyzes rapidly by collision with water vapor / droplets in the form of fine droplets, the product can still yield powder with a D50 of about 45 nm, and no solvent is used, resulting in a higher concentration of recovered hydrochloric acid (about 25 wt%).

[0091] This embodiment illustrates that the present invention is suitable for various operating modes.

[0092] In summary, this invention achieves ultra-fast mixing of germanium tetrachloride and hydrolysant through in vitro focused jetting, and fundamentally solves the problems of germanium dioxide back-dissolution and particle coarsening by using vacuum in-situ displacement of HCl. The prepared nano-germanium dioxide has high purity, narrow and controllable particle size distribution, and the byproduct hydrochloric acid can be recycled. The entire process is continuous and stable, with both environmental and economic benefits, and is suitable for large-scale industrial production of nano-germanium dioxide.

[0093] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride using an in vitro focused jet microreactor, characterized in that, Includes the following steps: (1) Prepare germanium tetrachloride into a solution or use pure liquid germanium tetrachloride directly; (2) Use ultrapure water or ultrapure water containing dispersant as the hydrolysate; (3) The germanium tetrachloride and the hydrolysant are respectively sprayed into the closed reaction chamber through the nozzle in the form of jets, and they collide at a focal point in the chamber to carry out a rapid hydrolysis reaction to generate nano germanium dioxide. (4) While the reaction is in progress, the sealed reaction chamber is evacuated to immediately remove the hydrogen chloride gas and volatile solvent vapor generated by hydrolysis from the chamber and condense and recover them through a condenser. (5) Collect the nano-germanium dioxide powder generated by the reaction, and obtain the product after washing and drying.

2. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (3), the jet injection method is any one of two-jet collision focusing, multi-jet confocal focusing, or coaxial ring tube jet focusing.

3. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (3), the nozzle outlet inner diameter is 0.1-2 mm and the flow velocity is 1-20 m / s.

4. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (4), the material of the sealed reaction chamber is selected from any one of PEEK polyether ether ketone, polytetrafluoroethylene, alumina ceramic, silicon carbide ceramic or high-purity quartz glass.

5. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (4), vacuum pumping is used to maintain the absolute pressure inside the cavity at 10 kPa-100 kPa.

6. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (4), pure germanium tetrachloride is used for hydrolysis, and the volume ratio of germanium tetrachloride to water is 1:2-1:

10. Alternatively, the concentration of the germanium tetrachloride solution can be 0.05~2.0 mol / L, and the solvent can be any one of ethanol, isopropanol, acetone, acetonitrile, or tetrahydrofuran.

7. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (4), the temperature inside the reaction chamber is controlled at 20~80℃.

8. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (5), the drying is vacuum freeze drying or vacuum drying at a temperature below 80°C.

9. The method for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride in an in vitro focused jet microreactor according to claim 1, characterized in that, In step (5), the purity of germanium dioxide is above 99.99%, and the D50 particle size is 10-200nm.

10. An apparatus for preparing nano-germanium dioxide by hydrolyzing germanium tetrachloride using an in vitro focusing jet microreactor, characterized in that, include: 3D printed microreactors, negative pressure chambers, and product collection and post-processing units. The 3D printed microreactor is made of corundum / zirconia / PEEK and is equipped with at least one germanium tetrachloride nozzle and at least one hydrolysate nozzle. The nozzle spraying directions converge at the same focal point inside the reactor. It is also equipped with a raw material delivery pump that is connected to the nozzle respectively, for accurately delivering germanium tetrachloride and deionized water; The negative pressure chamber has a vacuum extraction port on its wall, which is connected to a condenser, a gas-liquid separator and a vacuum pump in sequence through pipes, and is used to remove the HCl gas and reaction heat vapor generated in the reaction. The product collection and post-processing unit, located downstream of the cavity, includes a filtration, washing, and drying module for collecting slurry containing nano-germanium dioxide and preparing nano-germanium dioxide products with narrow particle size distribution, while simultaneously separating dilute hydrochloric acid waste liquid.

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