A system apparatus and method for preparing a silica gel

Abstract

The application discloses a system device and a method for preparing silicic acid gel; the system device comprises a liquid raw material tank, a gas cylinder, a supergravity reactor, a product collecting tank and a gas recovery device; the supergravity reactor comprises a shell, a liquid feeding port, a gas feeding port, a liquid discharging port, a gas outlet, a rotor, a motor, a rotating shaft and a coupling; the motor is connected with the rotating shaft arranged in the shell through the coupling, and the rotating shaft is connected with the rotor and fixed; the application further discloses a method for preparing silicic acid gel by using the system device. The silicic acid gel prepared by the system and the method has an actual yield of 94%; after aging, washing and drying, the specific surface area of the silicic acid gel is 335-400 m 2 / g, the pore volume is 0.50-0.75 cm 3 / g, and the pore size is mainly distributed in the range of 6-9 nm.

Description

Technical Field

[0001] This invention belongs to the field of inorganic catalytic material preparation technology, specifically relating to a system and method for preparing silica gel; and more particularly to a system and method for preparing silica gel by using a supergravity reactor to enhance the carbonation process. Background Technology

[0002] Silicate gels are important precursors for silica formation and have wide applications in inorganic binders, coating materials, catalyst supports, adsorbents, and composite materials. Current silica gel preparation processes typically use sodium silicate as the silicon source, adding acidifying agents such as hydrochloric acid or sulfuric acid to induce protonation and condensation of silicate ions. Due to the rapid reaction rate between strong inorganic acids and sodium silicate, the mixing of the acid solution and sodium silicate solution is poor in conventional stirred tanks, resulting in uneven local concentrations and a mismatch with the mass transfer process. This can lead to asynchronous nucleation and particle growth of silica gels, causing problems such as localized gelation, widened particle size distribution, and poor batch-to-batch stability. Furthermore, traditional acid-based reactions generate salty byproducts, often requiring multiple water washings, which increases process complexity, water consumption, and the burden on saline wastewater treatment. Simultaneously, using strong acids as acidifying agents necessitates consideration of the corrosive effects of the acidic medium on equipment materials, leading to high equipment requirements and significant investment costs.

[0003] In recent years, using gaseous carbon dioxide instead of inorganic acids in the carbonation reaction with sodium silicate solution has become a new technical route for preparing silica gel. This method effectively avoids the formation of salt-containing byproducts in the traditional acid reaction process, and the carbonic acid formed by the dissolution of carbon dioxide replaces the strong acid, effectively avoiding equipment corrosion. However, when the carbon dioxide and sodium silicate solution are unevenly distributed in the reactor, local areas are prone to over-acidification, premature gelation, material deposition, and wide product particle size distribution, which is not conducive to the continuous and stable operation of the reaction process. In addition, in traditional stirred tank reactors, the small effective gas-liquid contact area and slow interface renewal rate result in low gas-liquid mass transfer rate and long reaction time.

[0004] The centrifugal force field generated by the high-speed rotation of a rotor inside the hypergravity reactor disperses the liquid into micron-sized liquid films, filaments, or droplets, thereby greatly increasing the gas-liquid contact area and accelerating interfacial renewal. When applied to the carbonation process for preparing silica gels, this significantly improves the gas-liquid mass transfer rate and reduces reaction time. Inside the hypergravity reactor, the gas is a continuous phase, filling the entire reactor, while the liquid is uniformly dispersed into micron-sized liquid units. This effectively avoids uneven concentration, which can lead to localized gelation and poor batch stability of the product.

[0005] In light of this, Chinese patent application CN1394803A discloses a technical solution entitled "Two-Step Carbonation Reaction Process for Preparing Nano-Silica." This technical solution uses sodium silicate and carbon dioxide gas as raw materials, and carries out a carbonation reaction in a hypergravity field reactor. The reaction solution is then precipitated, filtered, washed, dried, pulverized, and sieved. This process eliminates the need for recirculation of the reaction solution, significantly shortening the carbonation reaction time. No flocculant is added to the raw materials, and the fine particles immediately precipitate in hot water after the reaction, eliminating the need for acidification and aging with hydrochloric acid, thus preventing the influence of chloride ions on the product and reducing agglomeration time. However, this technical solution still has the following shortcomings: 1) The silica gel has high viscosity and is prone to agglomeration and blockage after leaving the high-speed rotating rotor, especially on the inner wall of the reactor, affecting the specific surface area and pore size of the silica gel; 2) Although the carbonation reaction is enhanced by a hypergravity field, the control over the nucleation, growth, and aggregation processes of the silica gel is still insufficient, making it difficult to effectively control the pore size and pore size distribution of the obtained silica gel; 3) This technical solution mainly focuses on shortening the carbonation reaction time, paying insufficient attention to improving the yield of silica gel and the utilization rate of raw materials, making it difficult to achieve a high product yield; 4) There is a lack of targeted control over the specific surface area and pore structure of the silica gel, making it difficult to obtain a high-performance silica gel with both a high specific surface area and a suitable pore size distribution. The specific surface area, pore size, and pore size distribution of silica gel have a significant impact on its subsequent catalyst preparation and active component loading. Therefore, it is crucial to develop a preparation system and method that can improve the yield of silica gel and achieve effective control over its pore size and specific surface area. Summary of the Invention

[0006] The first technical problem this invention aims to solve is to provide a system apparatus for preparing silica gel. This system apparatus can effectively avoid problems such as uneven concentration, which can lead to localized gelation and poor batch stability of the product. The system apparatus combines a hypergravity reactor with an ultrasonic device, thereby enhancing the reaction while effectively preventing the adhesion and aggregation of silica gel.

[0007] The second technical problem to be solved by this invention is to provide a method for preparing silica gel using the above-described system apparatus. The actual yield of silica gel prepared by this invention reaches ≥94%. After aging, washing, and drying, the obtained silica gel has a specific surface area of ​​335-400 m². 2 / g, pore volume 0.50-0.75 cm³ 3 / g, with pore sizes mainly concentrated in the range of 6–9 nm.

[0008] To solve the first technical problem mentioned above, the present invention adopts the following technical solution: A system apparatus for preparing silica gel includes a liquid raw material tank, a gas cylinder, a hypergravity reactor, a product collection tank, and a gas recovery device; The hypergravity reactor includes a shell, a liquid inlet, a gas inlet, a liquid outlet, a gas outlet, a rotor, a motor, a shaft, and a coupling; the motor is connected to the shaft located inside the shell via the coupling, and the shaft is fixedly connected to the rotor. The liquid raw material tank is connected to the liquid inlet of the supergravity reactor via a pipeline, and a flow meter is installed on the pipeline connecting the liquid raw material tank and the liquid inlet. The gas cylinder is connected to the gas inlet of the hypergravity reactor via a pipeline; The liquid outlet of the supergravity reactor is connected to the product collection tank via a pipe; The gas outlet of the supergravity reactor is connected to a gas recovery device via a pipeline.

[0009] Preferably, an ultrasonic transmitter capable of emitting ultrasonic waves into the interior of the hypergravity reactor is fixedly mounted on the shell of the hypergravity reactor.

[0010] Preferably, a pH meter is provided between the liquid outlet of the supergravity reactor and the product collection tank.

[0011] Preferably, the rotor is fitted with a metal wire mesh packing, foam metal packing, or porous ceramic packing.

[0012] Preferably, the hypergravity reactor further includes a stator, and the rotor and stator form a stator-rotor column structure to enhance the shearing of materials, especially silica gel; the liquid inlet is connected to the inner circumference of the rotor, and the gas inlet is connected to the outer circumference of the rotor.

[0013] Preferably, the surfaces of the stator and rotor column structures are treated with hydrophobicity to change their wettability; the contact angle between the stator and rotor column structures and the raw material liquid is 30-160°, preferably 150°.

[0014] To solve the second technical problem mentioned above, the present invention adopts the following technical solution: A method for preparing silica gel using the above-described system apparatus includes the following steps: S1. Add sodium silicate to deionized water and heat to 20–90 °C with stirring until the sodium silicate is completely dissolved, obtaining a clear sodium silicate solution; the concentration of the sodium silicate solution is 1–60 wt%. S2. Open the gas cylinder and set the CO2 inlet flow rate to 500-20000 L / h; S3. Start the hypergravity reactor and set the rotation speed to 400-5000 r / min; S4. Start the ultrasonic transmitter and set the ultrasonic power to 100-600W; S5. The sodium silicate solution obtained in step S1 is continuously fed into the hypergravity reactor through the liquid inlet at a volumetric flow rate of 30-2000 L / h, and CO2 gas is continuously fed into the hypergravity reactor through the gas inlet. Under the centrifugal force generated by the rotor rotation, the sodium silicate solution flows from the inner circumference of the rotor to the outer circumference and disperses to form a liquid film, liquid filaments or droplets. The CO2 gas flows through the rotor from the outer circumference to the inner circumference, and reacts with the sodium silicate solution during this period to form a high-viscosity silicate gel product. After leaving the rotor from the outer circumference, the silicate gel product impacts the inner wall of the hypergravity reactor shell. Under the action of ultrasound, it is vibrated and dispersed, reducing the adhesion, deposition and agglomeration of silicate gel on the inner wall of the reactor and at the liquid outlet channel, and promoting the flow of reactants to the liquid outlet. S6. Monitor the pH value of the reaction solution at the liquid outlet of the centrifugal reactor. When the pH value of the reaction solution is 8.0 to 8.5, the reaction ends. S7. After the reaction is complete, collect the reactants; unreacted gas is discharged from the gas outlet and transported to the gas recovery device for recovery or recycling; silica gel product is transported to the product collection tank for collection.

[0015] Preferably, in step S1, the concentration of the sodium silicate solution is 10-30 wt%.

[0016] Preferably, in step S2, the intake flow rate is set to 3000-5000 L / h.

[0017] Preferably, in step S3, the volumetric flow rate of the sodium silicate solution is 70-500 L / h.

[0018] Preferably, in step S3, the rotor speed inside the hypergravity reactor is 400-5000 r / min; more preferably, the speed is 1500-5000 r / min; even more preferably, the speed is 1800-5000 r / min.

[0019] Preferably, in step S4, the power of the ultrasonic wave is 100-400W.

[0020] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0021] Unless otherwise specified, all raw materials used in this invention can be obtained commercially, and the equipment used in this invention can be conventional equipment in the relevant field or refer to existing technology in the relevant field.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) This invention fully utilizes the advantages of supergravity reactors in gas-liquid mass transfer. Inside the supergravity reactor, the liquid is dispersed into micron-sized liquid films, filaments, or droplets, thereby greatly increasing the gas-liquid contact area and accelerating interface renewal. When applied to the carbonation process to prepare silica gel, it significantly improves the gas-liquid mass transfer rate and reduces the reaction time.

[0024] 2) Inside the supergravity reactor of this invention, the gas is a continuous phase that fills the entire reactor, while the liquid is uniformly dispersed into micron-sized liquid units, which can effectively avoid uneven concentration, thereby preventing problems such as local gelation and poor batch stability of products.

[0025] 3) In this invention, the rotor inside the supergravity reactor is optimized through a combination of macro- and micro-scale processes to enhance the carbonation reaction for the preparation of silica gel. At the macro level, the rotor structure type can be freely adjusted; at the micro level, the wettability of the rotor surface is adjustable, achieving self-cleaning.

[0026] 4) This invention combines a hypergravity reactor with an ultrasonic device. The hypergravity reactor enhances the reaction in the rotor region. Unreacted material, mixed with the generated silica gel, leaves the rotating rotor region and, as a micron-sized liquid-solid gel mixture, comes into contact with the gas in the cavity region of the hypergravity reactor for further reaction. Subsequently, it impacts the reactor wall. Due to the high viscosity of the liquid-solid gel mixture, it deforms upon impact with the wall, encapsulating a large amount of gas and forming bubbles. Utilizing the cavitation effect of the ultrasonic device on the wall, the bubbles can be induced to break, increasing the gas-liquid contact surface area, further enhancing the reaction, and promoting the further transformation of unreacted material into silica gel.

[0027] 5) This invention utilizes the cavitation effect of an ultrasonic device. The ultrasonic device is installed on the outer wall of the hypergravity reactor, which can effectively prevent the adhesion and aggregation of high-viscosity silica gel on the inner wall of the reactor, promote its rapid peeling and removal from the inner wall of the reactor, and keep the inner wall clean.

[0028] 6) This invention combines a supergravity reactor with an ultrasonic device to enhance the reaction while effectively preventing the adhesion and aggregation of silica gel. Using the system of this invention, the actual yield of silica gel is ≥94%. After aging, washing, and drying, the obtained silica gel has a specific surface area of ​​335-400 m². 2 / g, pore volume 0.50-0.75cm 3 / g, with pore sizes mainly concentrated in the range of 6–9 nm. Attached Figure Description

[0029] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Figure 1 This is a schematic diagram of the system apparatus for preparing silica gel according to the present invention. Detailed Implementation

[0030] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0031] As one aspect of the present invention, a system apparatus for preparing silica gel is provided, comprising a liquid raw material tank 1, a gas cylinder 2, a supergravity reactor 7, a product collection tank 9, and a gas recovery device 10. The hypergravity reactor 7 includes a shell 71, a liquid inlet 72, a gas inlet 73, a liquid outlet 74, a gas outlet 75, a rotor 76, a motor 77, a rotating shaft 78, and a coupling 79. The motor 77 is connected to the rotating shaft 78 located inside the shell 71 via the coupling 79. The rotating shaft 78 is fixedly connected to the rotor 76, thereby driving the rotor 76 to rotate at high speed under the driving action of the motor 77, generating a hypergravity field. The liquid raw material tank 1 is connected to the liquid inlet 72 of the supergravity reactor 7 via a pipeline, and a flow meter 14 is provided on the pipeline connecting the liquid raw material tank 1 and the liquid inlet 72 for conveying sodium silicate solution to the supergravity reactor 7. The gas cylinder 2 is connected to the gas inlet 73 of the hypergravity reactor 7 via a pipeline, and is used to supply CO2 gas to the hypergravity reactor 7. The liquid outlet 74 of the supergravity reactor 7 is connected to the product collection tank 9 through a pipe for collecting the silica gel generated in the reaction. The gas outlet 75 of the supergravity reactor 7 is connected to the gas recovery device 10 through a pipeline to collect unreacted CO2 gas and realize the recovery and utilization of tail gas.

[0032] According to certain embodiments of the present invention, an ultrasonic transmitter 15 is fixed on the shell 71 of the hypergravity reactor 7, which can emit ultrasonic waves into the shell 71 of the hypergravity reactor; after the product silica gel leaves the high-speed rotating rotor area, it will impact the inner wall of the reactor shell 71. The silica gel has a high viscosity, and the ultrasonic action can be used to remove the silica gel adhering to the inner wall of the shell.

[0033] According to certain embodiments of the present invention, a pH meter 16 is provided between the liquid outlet of the supergravity reactor and the product collection tank.

[0034] According to certain embodiments of the present invention, the rotor 76 is fitted with a metal wire mesh packing, a foam metal packing, or a porous ceramic packing.

[0035] According to certain embodiments of the present invention, the supergravity reactor 7 further includes a stator (not shown in the figure), and the rotor and stator form a stator-rotor column structure to enhance the shearing of materials, especially silica gel, etc.; the liquid inlet is connected to the inner circumference of the rotor, and the gas inlet is connected to the outer circumference of the rotor.

[0036] According to certain embodiments of the present invention, the surfaces of the stator and rotor column structures are hydrophobically treated to change their wettability, so that the silica gel cannot adhere to the surface and the rotor has a self-cleaning function; the contact angle between the stator and rotor column structures and the raw material liquid can be freely adjusted between 30-160°, preferably 150°.

[0037] As another aspect of the present invention, a method for preparing silica gel using the above-described system apparatus includes the following steps: S1. Add sodium silicate to deionized water and heat to 20–90 °C with stirring until the sodium silicate is completely dissolved, obtaining a clear sodium silicate solution; the concentration of the sodium silicate solution is 1–60 wt%. S2. Open the gas cylinder and set the CO2 inlet flow rate to 500-20000 L / h; S3. Start the hypergravity reactor and set the rotation speed to 400-5000 r / min; S4. Start the ultrasonic transmitter and set the ultrasonic power to 100-600W; S5. The sodium silicate solution obtained in step S1 is continuously fed into the hypergravity reactor through the liquid inlet at a volumetric flow rate of 30-2000 L / h, and CO2 gas is continuously fed into the hypergravity reactor through the gas inlet. Under the centrifugal force generated by the rotor rotation, the sodium silicate solution flows from the inner circumference of the rotor to the outer circumference and disperses to form a liquid film, liquid filaments or droplets. The CO2 gas flows through the rotor from the outer circumference to the inner circumference, and reacts with the sodium silicate solution during this period to form a high-viscosity silicate gel product. After leaving the rotor from the outer circumference, the silicate gel product impacts the inner wall of the hypergravity reactor shell. Under the action of ultrasound, it is vibrated and dispersed, reducing the adhesion, deposition and agglomeration of silicate gel on the inner wall of the reactor and at the liquid outlet channel, and promoting the flow of reactants to the liquid outlet. S6. Monitor the pH value of the reaction solution at the liquid outlet of the centrifugal reactor. When the pH value of the reaction solution is 8.0 to 8.5, the reaction ends. S7. After the reaction is complete, collect the reactants; unreacted gas is discharged from the gas outlet and transported to the gas recovery device for recovery or recycling; silica gel product is transported to the product collection tank for collection.

[0038] According to certain embodiments of the present invention, in step S1, the concentration of the sodium silicate solution is 10-30 wt%.

[0039] According to certain embodiments of the present invention, in step S2, the intake flow rate is set to 3000-5000 L / h.

[0040] According to certain embodiments of the present invention, in step S3, the volumetric flow rate of the sodium silicate solution is 70-500 L / h.

[0041] According to some embodiments of the present invention, in step S3, the rotor speed inside the hypergravity reactor is 1500-5000 r / min; more preferably, the speed is 1800-5000 r / min.

[0042] According to certain embodiments of the present invention, in step S4, the power of the ultrasonic wave is 100-400W.

[0043] Example 1 See Figure 1 As shown, a method for preparing silica gel using the system device of the present invention includes the following steps: 1) Prepare 70 L of 20 wt% sodium silicate solution and add it to the raw material tank (density 1.2 kg / L). Turn on the stirrer and heat it to 88 ℃ at a heating rate of about 2 ℃ / min. Hold the temperature for 10 min to reduce the viscosity of the solution. 2) Start the hypergravity reactor and set the rotor speed to 1800 r / min; 3) Turn on the ultrasonic transmitter and set the rated output power to 100 W; 4) The liquid feed rate of sodium silicate solution is 70 L / h, and CO2 gas is fed into the supergravity reactor at a flow rate of 3725 L / h. The gas and liquid phases are in countercurrent contact in the rotor mass transfer zone. 5) Monitor the pH at the outlet of the centrifugal reactor online. The reaction ends when the pH of the reaction solution reaches 8.2. 6) After the reaction is complete, collect the product, let it stand and filter it to produce 10.21 kg of silica gel.

[0044] The yield of the silica gel obtained in this embodiment was 94.9% as tested. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was found to be 350 m². 2 / g, pore volume 0.55 cm³ 3 / g, with pore sizes mainly distributed in the range of 6–9 nm. Example 2

[0045] Repeat Example 1, except that in step 3), the output power of the ultrasonic transmitter is set to 400W; 10.31 kg of silica gel is generated.

[0046] The yield of the silica gel obtained in this embodiment was 95.9% as tested. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was found to be 368 m². 2 / g, pore volume approximately 0.66 cm³ 3 / g, with pore sizes mainly distributed in the range of 6–9 nm. Example 3

[0047] The same example as Example 1 is repeated, except that in step 3), the output power of the ultrasonic transmitter is set to 600W; in step 4), the CO2 gas flow rate is 3800 L / h; and 10.46 kg of silica gel is generated.

[0048] The yield of the silica gel obtained in this embodiment was 97.3% as tested. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was found to be 337 m². 2 / g, pore volume approximately 0.58 cm³ 3 / g, with pore sizes mainly distributed in the range of 6–9 nm. Example 4

[0049] Example 1 was repeated, except that in step 2), the rotor speed was set to 5000 r / min. 10.59 kg of silica gel was generated.

[0050] The yield of the silica gel obtained in this embodiment was 98.5% as tested. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was found to be 400 m². 2 / g, pore volume approximately 0.72 cm³ 3 / g, with pore sizes mainly distributed in the range of 6–8 nm. Example 5

[0051] Example 1 was repeated, except that in step 4), a 70 L, 20 wt% sodium silicate solution was prepared, the liquid feed rate was 80 L / h, and CO2 gas was fed into the hypergravity reactor at a flow rate of 3550 L / h. After the reaction was completed, the product was collected, allowed to stand, and filtered to produce 11.58 kg of silica gel.

[0052] The yield of the silica gel obtained in this embodiment was 94.3% as tested. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was found to be 339 m². 2 / g, pore volume approximately 0.68 cm³ 3 / g, with pore sizes mainly distributed in the range of 6–9 nm.

[0053] Comparative Example 1 Example 1 was repeated, except that in step 2), the rotation speed of the hypergravity reactor was set to 390 r / min, and the other conditions were the same as in Example 1, resulting in the production of 9.56 kg of silica gel.

[0054] The yield of the silica gel obtained in this comparative example was 88.9%. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was approximately 270 m². 2 / g, pore volume approximately 0.42 cm³ 3 / g, pore size is mainly distributed in the range of 4 to 11 nm. The results show that when the rotor speed is too low, the gas-liquid mixing and mass transfer enhancement under hypergravity conditions are insufficient, the yield of the obtained silica gel is significantly lower than that of Example 1, and the specific surface area and pore volume are reduced, while the pore size distribution range is widened.

[0055] Comparative Example 2 Repeat Example 1, except that in step 2), the rotor speed of the hypergravity reactor is set to 6000 r / min to generate 9.48 kg of silica gel.

[0056] The yield of the silica gel obtained in this comparative example was 88.2%. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was approximately 315 m². 2 / g, pore volume approximately 0.39 cm³ 3 / g, pore size is mainly distributed in the range of 5-11 nm. The results show that excessively high rotor speed also leads to a significantly lower actual yield of the silica gel product compared to Example 1. At the same time, the specific surface area and pore volume decrease, and the pore size distribution range widens. This indicates that excessively high rotor speed is not conducive to achieving both a high yield of silica gel and good pore structure performance.

[0057] Comparative Example 3 Repeat Example 1, except that in step 4), the CO2 gas flow rate is 2500 L / h; 8.23 ​​kg of silica gel is generated.

[0058] The yield of the silica gel obtained in this embodiment was 76.5% according to the test results. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was approximately 280 m². 2 / g, pore volume approximately 0.43 cm³ 3 / g, with pore sizes mainly distributed in the range of 5–11 nm.

[0059] The results showed that when the CO2 feed amount was insufficient, the carbonation reaction of sodium silicate was affected, resulting in a significant decrease in the actual yield of silica gel. At the same time, the specific surface area and pore volume of the obtained silica gel were significantly reduced compared with Example 1, and the pore size distribution range became wider.

[0060] Comparative Example 4 Example 1 was repeated, except that the hypergravity reactor was replaced with a conventional stirred tank, producing 7.35 kg of silica gel.

[0061] The yield of the silica gel obtained in this comparative example was 68.4%. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was approximately 220 m². 2 / g, pore volume approximately 0.32 cm³ 3 / g, with pore sizes mainly distributed in the range of 4–12 nm.

[0062] Comparative Example 5 Repeat Example 1, except that in step 3), the ultrasonic transmitter is not turned on, and 9.72 kg of silica gel is generated.

[0063] The yield of the silica gel obtained in this comparative example was 90.4%. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was approximately 305 m². 2 / g, pore volume approximately 0.45 cm³ 3 / g, with pore sizes mainly distributed in the range of 5–10 nm.

[0064] Comparative Example 6 Example 1 was repeated, except that in step 3), the position of the ultrasonic transmitter was changed to inside the hypergravity reactor to generate 9.76 kg of silica gel.

[0065] The yield of the silica gel obtained in this comparative example was 90.8%. The obtained silica gel was characterized after aging, washing, and drying, and its specific surface area was approximately 310 m². 2 / g, pore volume approximately 0.46cm³ 3 / g, with pore sizes mainly distributed in the range of 5–10 nm.

[0066] The results show that placing the ultrasonic transmitter inside the hypergravity reactor prevents the silica gel product impacting the inner wall of the reactor shell from being vibrated and dispersed by the ultrasonic waves, thus reducing the adhesion, deposition, and aggregation of silica gel on the reactor shell and in the liquid outlet channel. This results in a lower yield of silica gel compared to Example 1 where the ultrasonic transmitter was placed on the reactor shell. Simultaneously, the specific surface area and pore volume are reduced, while the pore size distribution range becomes wider. This indicates that placing the ultrasonic transmitter on the reactor shell is more beneficial for further improving the yield of silica gel and its pore structure.

[0067] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A system apparatus for preparing silica gel, characterized in that, Includes liquid raw material tanks, gas cylinders, centrifugal reactors, product collection tanks, and gas recovery devices; The hypergravity reactor includes a shell, a liquid inlet, a gas inlet, a liquid outlet, a gas outlet, a rotor, a motor, a shaft, and a coupling; the motor is connected to the shaft located inside the shell via the coupling, and the shaft is fixedly connected to the rotor. The liquid raw material tank is connected to the liquid inlet of the supergravity reactor via a pipeline, and a flow meter is installed on the pipeline connecting the liquid raw material tank and the liquid inlet. The gas cylinder is connected to the gas inlet of the hypergravity reactor via a pipeline; The liquid outlet of the supergravity reactor is connected to the product collection tank via a pipe; The gas outlet of the supergravity reactor is connected to a gas recovery device via a pipeline.

2. The system apparatus according to claim 1, characterized in that: An ultrasonic transmitter capable of emitting ultrasonic waves into the interior of the supergravity reactor is fixedly mounted on the shell of the supergravity reactor.

3. The system apparatus according to claim 1, characterized in that: A pH meter is installed between the liquid outlet of the supergravity reactor and the product collection tank.

4. The system apparatus according to claim 1, characterized in that: The rotor is fitted with metal wire mesh packing, foam metal packing, or porous ceramic packing.

5. The system apparatus according to claim 1, characterized in that: The hypergravity reactor also includes a stator, a rotor, and a stator-rotor column structure; the liquid inlet is connected to the inner circumference of the rotor, and the gas inlet is connected to the outer circumference of the rotor.

6. The system apparatus according to claim 5, characterized in that: The surfaces of the stator and rotor column structures are all treated with hydrophobicity to change their wettability; the contact angle between the stator and rotor column structures and the raw material liquid is 30-160°, preferably 150°.

7. A method for preparing silica gel using the system apparatus according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Add sodium silicate to deionized water and heat to 20–90 °C with stirring until the sodium silicate is completely dissolved, obtaining a clear sodium silicate solution; the concentration of the sodium silicate solution is 1–60 wt%. S2. Open the gas cylinder and set the CO2 inlet flow rate to 500-20000 L / h; S3. Start the hypergravity reactor and set the rotation speed to 400-5000 r / min; S4. Start the ultrasonic transmitter and set the ultrasonic power to 100-600W; S5. The sodium silicate solution obtained in step S1 is continuously fed into the hypergravity reactor through the liquid inlet at a volumetric flow rate of 30-2000 L / h, and CO2 gas is continuously fed into the hypergravity reactor through the gas inlet. Under the centrifugal force generated by the rotor rotation, the sodium silicate solution flows from the inner circumference of the rotor to the outer circumference and disperses to form a liquid film, liquid filaments or droplets. The CO2 gas flows through the rotor from the outer circumference to the inner circumference, and reacts with the sodium silicate solution during this period to form a high-viscosity silicate gel product. After leaving the rotor from the outer circumference, the silicate gel product impacts the inner wall of the hypergravity reactor shell. Under the action of ultrasound, it is vibrated and dispersed, reducing the adhesion, deposition and agglomeration of silicate gel on the inner wall of the reactor and at the liquid outlet channel, and promoting the flow of reactants to the liquid outlet. S6. Monitor the pH value of the reaction solution at the liquid outlet of the centrifugal reactor. When the pH value of the reaction solution is 8.0 to 8.5, the reaction ends. S7. After the reaction is complete, collect the reactants; unreacted gas is discharged from the gas outlet and transported to the gas recovery device for recovery or recycling; silica gel product is transported to the product collection tank for collection.

8. The method for preparing silica gel according to claim 7, characterized in that: In step S1, the concentration of the sodium silicate solution is 10-30 wt%.

9. The method for preparing silica gel according to claim 7, characterized in that: In step S2, the intake flow rate is set to 3000-5000 L / h.

10. The method for preparing silica gel according to claim 7, characterized in that: In step S3, the volumetric flow rate of the sodium silicate solution is 70-500 L / h; Preferably, in step S3, the rotor speed inside the hypergravity reactor is 400-5000 r / min; more preferably, the speed is 1500-5000 r / min; even more preferably, the speed is 1800-5000 r / min. Preferably, in step S4, the power of the ultrasonic wave is 100-400W.

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