Process for the preparation of silica gel microspheres for use as catalyst supports

Abstract

The present application relates to a kind of silica gel microspheres preparation method used as catalyst carrier, by controlling material temperature, material concentration, multiple acidification etc. Means to adjust the speed of acidification water glass to gel conversion, after acidification water glass atomization forms droplet, quickly convert into gel, again through aging, pickling, washing, supercritical carbon dioxide drying, atmosphere furnace calcination etc. Process, high specific surface area, macropore volume silica gel microspheres are prepared. Compared with prior art, the specific surface area of silica gel obtained by the present application can reach 250-450m 2 / g, pore volume can reach 1.5-3.0cm 3 / g, and has good strength and fluidity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to a method for preparing silica microspheres used as catalyst supports. Background Technology

[0002] Silica gel has a wide range of applications. Among them, microsphere silica gel with large pore volume, large pore size and high specific surface area is particularly suitable for polyolefin catalyst support, especially metallocene catalyst support, due to its suitable pore volume, pore size, specific surface area and good flowability.

[0003] There are various methods for preparing silica microspheres. The most common method uses silicates and inorganic acids as raw materials, reacting them at a specific pH value to form a gel. The gel is then subjected to aging, acid washing, water washing, drying, or spray molding and calcination to obtain the silica microspheres. Existing technologies, such as patent documents CN113754798A, CN110732341A, and CN106622378B, all involve first preparing a gel raw material, then crushing it into a slurry, and finally obtaining silica microspheres through spray drying.

[0004] However, this traditional method for preparing silica microsphere carriers has two shortcomings: (1) Existing silica microspheres are difficult to achieve both high specific surface area and large pore volume at the same time, and the specific surface area is often sacrificed for the sake of large pore volume. (2) The spray drying process affects the strength of silica microspheres. Silica powder forms a microsphere structure through the action of a binder. Due to the difference in thermal expansion coefficients between the binder and the silica powder, silica microspheres are prone to collapse and cracking when heated or cooled.

[0005] Therefore, new methods must be adopted to prepare silica microspheres with high specific surface area, high pore volume, good strength and flowability to meet the requirements of catalyst support. Summary of the Invention

[0006] The purpose of this invention is to overcome at least one defect of the prior art and provide a method for preparing silica microspheres as catalyst supports, which can obtain silica microspheres with high specific surface area, high pore volume, good strength and flowability.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide a method for preparing silica microspheres used as catalyst supports, comprising the following steps:

[0009] (1) Add the beta molecular sieve modified powder to water glass solution and stir thoroughly to obtain mixture A; mix it with sulfuric acid solution B and stir at high speed to obtain mixture D;

[0010] (2) The mixture D, which is pre-cooled to -4 to 0°C, is rapidly mixed with another sulfuric acid solution B, which is pre-cooled to -4 to 0°C. The resulting material d is rapidly mixed with the acid salt solution C. The resulting mixture e is atomized into droplets E under the shearing action of a high-pressure airflow. The droplets are collected using a flowing organic solvent, filtered, and then particles F are obtained.

[0011] (3) Disperse particle F in an aqueous solution of n-butanol, and then perform an aging treatment to obtain gel-aged particles G. Disperse G in an aqueous solution of oxalic acid, stir, heat to 50-70°C, treat for 1-2 hours, filter, and obtain particles H.

[0012] (4) Disperse particles H in deionized water, stir, wash, and filter to raise the pH of the washing water to above 5.5 to obtain washed particles I.

[0013] (5) Disperse particle I in low carbon alcohol, stir for 24 hours, filter, and obtain particle J. Dry with supercritical carbon dioxide, and select particles with a diameter between 10 and 150 micrometers by sieving to obtain particle K.

[0014] (6) Particle K is calcined by gradient heating to obtain silica microspheres.

[0015] Furthermore, the beta molecular sieve modified powder described in step (1) is prepared by the following method:

[0016] The beta molecular sieve is immersed in oxalic acid solution, heated to 50-70℃, stirred for 0.5-2 hours, and filtered; the above process is repeated several times; the obtained acid-treated beta molecular sieve is washed until the washing solution is nearly neutral, then dried and calcined to obtain beta molecular sieve modified powder.

[0017] Furthermore, the beta molecular sieve is a commercially available beta molecular sieve with a silicon-to-aluminum ratio (n(SiO2) / n(Al2O3), molar ratio) of 25-80:1 and a particle size of less than 1 micrometer.

[0018] The oxalic acid solution has a mass concentration of 0.5% to 2%.

[0019] The washed beta molecular sieves are dried at a temperature of 100–140℃, calcined at a temperature of 450–550℃, and calcined for 1–3 hours.

[0020] Further, the water glass solution described in step (1) is prepared by adding high-purity water glass to deionized water, wherein the amount of deionized water is 3 to 4 times the mass of high-purity water glass.

[0021] The high-purity water glass has a modulus of 3.1 to 3.7, a silicon dioxide mass fraction of 25% to 29%, and an impurity iron oxide mass fraction of less than 0.005% and an impurity aluminum oxide mass fraction of less than 0.07%.

[0022] Furthermore, the amount of beta molecular sieve modified powder in the mixture A is 1% to 15% of the mass of water glass;

[0023] The sulfuric acid solution B has a mass fraction of 5% to 10%.

[0024] The mass fraction of the acid salt solution C is 5% to 10%;

[0025] The acid salt used in acid salt solution C is selected from one or a mixture of sodium bicarbonate, ammonium bicarbonate, sodium bisulfate, and ammonium bisulfate.

[0026] Because the process of water glass transforming into a gel upon adding acid is extremely rapid, if the acid is added too quickly, gelation can be completed within seconds, leading to an uneven reaction system. To achieve the rapid formation of droplets from water glass after acid addition, followed by its rapid transformation into a gel, extremely high requirements are placed on pH control, temperature control, and rapid mixing of the reaction system. Therefore, this invention employs a stepwise acid addition method, adjusting the pH value of the system in stages to ensure that the system remains in a uniform reaction state, thus ensuring the adjustability and controllability of the microstructure.

[0027] Further, in step (1), the mixture A and sulfuric acid solution B are continuously fed into the first high-speed mixer with a cooling jacket at a mass flow ratio of 100:25 to 100:50 for high-speed mixing, and the mixing time is 2 to 10 minutes; the pH of the mixture D is 11 to 13.

[0028] Further, in step (2), the mixture D and sulfuric acid solution B are continuously fed into the second high-speed mixer at a mass flow ratio of 100:10 to 100:25 for rapid mixing. The mixing time is 15 to 60 seconds, and the pH of the mixed material is 10 to 12.

[0029] During the acidification process, water glass continuously generates metasilicic acid. Under strongly alkaline (pH 10–14) or strongly acidic (pH 1–4) conditions above room temperature, metasilicic acid can form a network structure through the condensation of silanol groups. When the network structure reaches a certain level, it becomes a gel, and the system loses its fluidity. Continued acidification inevitably leads to uneven mixing, inconsistent local pH environments, and inconsistent microstructures. As a catalyst carrier, this will affect the catalyst's reactivity. Furthermore, the reaction between sulfuric acid and water glass is a strongly exothermic reaction, requiring rapid removal of the heat of reaction. After a certain amount of sulfuric acid is added, the heat transfer capacity of the reaction system decreases sharply. Therefore, this invention achieves continuous preparation by rationally controlling the acid addition step and finely regulating the acid addition process.

[0030] The material d and the acid salt solution C are continuously fed into the high-speed mixer (3) at a mass flow ratio of 100:10 to 100:25 for rapid mixing and residence for 15 to 60 seconds. The resulting mixture e has a pH of 8 to 10 and is sprayed out from the bottom nozzle of the high-speed mixer (3). Under the shearing action of the high-pressure airflow, atomized droplets E are obtained.

[0031] Furthermore, the nozzle is a two-fluid nozzle, and the high-pressure gas flow is a mixture of nitrogen and carbon dioxide gas at 2-8 bar, wherein the carbon dioxide content is 20%-100%.

[0032] The organic solvent used to collect the atomized droplets E is aqueous n-butanol or isobutanol, wherein the mass fraction of water is 0.5% to 7%.

[0033] Furthermore, in step (3), the mass fraction of the aqueous solution of n-butanol is 0% to 5%;

[0034] The aging process is as follows: first heat to 50-70℃ and treat for 15-18 hours, then heat to 80-90℃ and treat for 3-6 hours;

[0035] The oxalic acid aqueous solution contains 0.1% to 1% oxalic acid by mass, and the amount of oxalic acid aqueous solution used is 16 to 20 times the mass of the gel-aged particles G.

[0036] The low-carbon alcohol mentioned in step (4) is ethanol, isopropanol or n-butanol, and the amount of low-carbon alcohol used is 15 to 25 times the mass of water-washed particles I.

[0037] The supercritical carbon dioxide drying in step (5) is performed at a pressure of 10-20 MPa, a temperature of 40-120°C, a carbon dioxide flow rate of 10-20 g carbon dioxide per gram of particles per hour, and a processing time of 2-4 hours.

[0038] Furthermore, the gradient heating method in step (6) is to stay at 300-400℃ for 0.5-1.5 hours, 500-600℃ for 1-3 hours, and 600-700℃ for 3-6 hours respectively, with the heating rate and cooling rate controlled at 0.5-1.5℃ / min;

[0039] The roasting is carried out in an air atmosphere, with an air flow rate of 0.2 to 2 L of air per gram of particle K per hour;

[0040] The silica microspheres have a SiO2 mass fraction greater than 99.9%, an Al2O3 mass fraction less than 0.05%, and a Na2O mass fraction less than 0.01%.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The method of this invention can prepare pores with a volume of 1.5–3.0 cm³. 3 / g, specific surface area 250~450m² 2 / g, spherical silica gel with a diameter of 10-150 micrometers; prepare micron-sized silica gel carriers, the reaction system is uniform, and the atomized liquid is naturally shaped by surface tension, resulting in spheric particles with good flowability.

[0043] (2) Beta molecular sieves possess a three-dimensional twelve-membered ring straight-channel pore structure with a wide adjustable range of silica-alumina ratio. They also exhibit high specific surface area, acid catalytic properties, and hydrothermal stability, making them widely used as catalyst supports in the chemical industry. This invention organically combines Beta molecular sieves with a high-performance silica gel support, which is beneficial for further expanding the application performance of the silica gel support.

[0044] The beta zeolite framework has pores of 0.75 nm. After acid treatment, some aluminum is removed from the framework, forming a mesoporous structure with a pore size of 2–6 nm. The gel encapsulating the beta zeolite transforms into a mesoporous structure with a pore size of 15–25 nm. These three structures combine to form a microsphere carrier with a hierarchical porous structure. The microporous structure provides a high specific surface area, while the mesoporous structure provides a high pore volume. Thus, the silica microspheres prepared in this invention maintain a high pore volume while possessing a high specific surface area.

[0045] After acid treatment, beta molecular sieves develop silanol groups (Si-OH) on their surface. During the subsequent gel condensation process, not only do the silanol groups in the gel condense to form Si-O-Si bonds, but the silanol groups on the surface of the beta molecular sieve also condense with the silanol groups in the gel to form Si-O-Si bonds. Therefore, the silica microspheres prepared in this invention have good strength and are not easily collapsed after immersion in liquid, which is beneficial for the catalyst loading process.

[0046] (3) During atomization, carbon dioxide gas diffuses into the droplets to replenish acid, causing the outer layer of the droplets to transform into a gel layer. When the droplets enter the flowing organic solvent, they remain dispersed, while the interior further gels and solidifies. Therefore, the silica microspheres prepared in this invention have a smooth surface, excellent sphericity, and good flowability.

[0047] (4) This invention breaks down the acid addition process into four steps: adding acid in a first high-speed mixer, adding acid in a second high-speed mixer, adding acidic salts in a third high-speed mixer, and adding acid by diffusing carbon dioxide gas into the droplets during atomization. In the first step, the system releases a large amount of heat and has low viscosity, making it easy to transfer heat; temperature is controlled by a cooling jacket. In the second step, the system viscosity increases significantly, reducing heat transfer capacity; low-temperature pretreatment of the reaction raw materials is used to control the temperature rise and avoid gelation. In the third step, acidic salts are used to further slowly lower the pH value of the system. In the fourth step, droplet atomization occurs, and carbon dioxide promotes the formation of atomized particles. In the fifth step, the water absorption of n-butanol (or isobutanol) is used to further solidify the microsphere gel. In the sixth step, acidic salts are used in conjunction with aging and other operational steps to further refine the internal pH adjustment. The entire process control window is extended, reducing the difficulty of control and facilitating industrialization. By precisely controlling the pH value and combining it with high-speed stirring to achieve uniform mixing, the system remains in a uniform state, achieving the goal of microstructural homogenization. Attached Figure Description

[0048] Figure 1 This invention provides a silica microsphere preparation system used as a catalyst support.

[0049] The diagram shows the following labels: 1 for tank A of mixed solution, 2 for tank B of solution, 3 for first metering pump, 4 for second metering pump, 5 for first high-speed mixer, 6 for third metering pump, 7 for tank D of solution, 8 for fourth metering pump, 9 for second high-speed mixer, 10 for second tank B of solution, 11 for fifth metering pump, 12 for sixth metering pump, 13 for third high-speed mixer, 14 for tank C of solution, 15 for seventh metering pump, 16 for eighth metering pump, 17 for atomizing nozzle, 18 for first gas flow controller, 19 for second gas flow controller, 20 for gas mixer, and 21 for container.

[0050] Figure 2 This is an electron microscope image of smooth silica microspheres prepared by the method described in this invention, at a magnification of 2000.

[0051] Figure 3 These are electron microscope images of commercially available silicone microspheres, magnified 300 times. Detailed Implementation

[0052] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0053] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0054] To address the shortcomings of traditional methods for preparing silica microsphere supports, this invention provides a novel method for preparing silica microspheres with high specific surface area, high pore volume, good strength, and good flowability to meet the requirements of catalyst supports. This method employs methods such as... Figure 1 The system shown includes a mixture A storage tank 1 and a first solution B storage tank 2. The mixture A storage tank 1 and the first solution B storage tank 2 are respectively connected to a first high-speed mixer 5 through pipelines. A first metering pump 3 and a second metering pump 4 are respectively installed on the connecting pipelines. The first high-speed mixer 5 is connected in sequence to a third metering pump 6, a solution D storage tank 7, a fourth metering pump 8, and a second high-speed mixer 9 through pipelines. The second solution B storage tank 10 is connected to the second high-speed mixer 9 through pipelines. A fifth metering pump 11 is installed on the pipeline. The second high-speed mixer 9 is connected in sequence to a sixth metering pump 12 and a third high-speed mixer 13 through pipelines. The third high-speed mixer 13 is also connected to a solution C storage tank 14. A seventh metering pump 15 is installed on the connecting pipeline. The bottom of the third high-speed mixer 13 is connected to an atomizing nozzle 17 through an eighth metering pump 16. The atomizing nozzle 17 is also connected to a gas mixer 20. The gas mixer 20 is connected to compressed nitrogen through a first gas flow controller 18 and to compressed carbon dioxide through a second gas flow controller 19.

[0055] The method for preparing silica microspheres for use as catalyst supports using the above system includes the following steps:

[0056] (1) Preparation of beta molecular sieve modified powder:

[0057] 11) Soak commercially available beta molecular sieves with a silicon-to-aluminum ratio (n(SiO2) / n(Al2O3), molar ratio) of 25-80 and a particle size of less than 1 micrometer in a 0.5-2% oxalic acid solution, heat to 50-70°C, stir for 0.5-2 hours, and filter; repeat the above process twice.

[0058] 12) Wash the acid-treated beta molecular sieve with deionized water until the washing solution is nearly neutral (pH 6-7);

[0059] 13) Dry the washed beta molecular sieve at 100-140℃ and calcine it at 450-550℃ for 1-3 hours or more.

[0060] (2) Dilute high-purity water glass with deionized water to prepare a dilute water glass solution, add beta molecular sieve modified powder to it, stir thoroughly to prepare a mixture A, and place it in a mixture A storage tank 1 equipped with a cooling device. Dilute sulfuric acid with deionized water to prepare sulfuric acid solution B, divide it into two portions, place one portion in a first solution B storage tank 2 equipped with a cooling device, and the other portion in a second solution B storage tank 10 equipped with a cooling device. Dissolve the acid salt with deionized water to prepare an acid salt solution C, and place it in a solution C storage tank 14 equipped with a cooling device.

[0061] The amount of beta molecular sieve modified powder used is 1% to 15% of the mass of high-purity water glass; the sulfuric acid is analytical grade, and the mass fraction of sulfuric acid in sulfuric acid solution B is 5% to 10%; the acid salt is one or a mixture of sodium bicarbonate, ammonium bicarbonate, sodium bisulfate, ammonium bisulfate, etc., and the mass fraction of acid salt in acid salt solution C is 5% to 10%.

[0062] (3) Mixture A and sulfuric acid solution B in the first solution B storage tank 2 are continuously fed into the first high-speed mixer 5 with a cooling jacket at a mass flow ratio of 100:25 to 100:50. After rapid mixing and residence for 2 to 10 minutes, the mixture is extracted from the first high-speed mixer 5 to obtain mixture D. The pH of mixture D is 11 to 13, and it is placed in solution D storage tank 7 with a cooling device.

[0063] (4) The mixture D, which is pre-cooled to -4 to 0°C in the storage tank 7 of solution D, and the sulfuric acid solution B, which is pre-cooled to -4 to 0°C in the storage tank 10 of the second solution B, are continuously fed into the second high-speed mixer 9 at a mass flow ratio of 100:10 to 100:25. After rapid mixing and residence for 15 to 60 seconds, the pH of the resulting material d is 10 to 12. The material d flows out into the third high-speed mixer 13 equipped with a cooling device and is rapidly mixed with the acid salt solution C output from the storage tank 14 of solution C. The mass flow ratio of material d and acid salt solution C into the third high-speed mixer 13 is 100:10 to 100:25. After residence for 15 to 60 seconds, the pH of the resulting mixture e is 8 to 10. The mixture is sprayed out from the atomizing nozzle 17 at the bottom of the third high-speed mixer 13. A high-pressure gas flow is injected into the atomizing nozzle 17 through the gas mixer 20. Under the shearing action of the high-pressure gas flow, atomized droplets E are obtained and placed in the container 21 for receiving droplets. The atomizing nozzle is a two-fluid nozzle, and the high-pressure airflow is a mixture of nitrogen and carbon dioxide gas at 2-8 bar, wherein the carbon dioxide content is 20%-100%.

[0064] Container 21 contains an organic solvent. The flowing organic solvent is used to collect and filter the particles F. The organic solvent used to collect the atomized droplets E is aqueous n-butanol or isobutanol, wherein the mass fraction of water is 0.5% to 7%.

[0065] (5) Disperse particle F in an aqueous solution containing n-butanol (0%–5% by mass), heat to 50–70°C, and treat for 15–18 hours. Then heat to 80–90°C and treat for 3–6 hours. Filter to obtain gel-aged particles G. Disperse G in an aqueous solution containing 0.1–1% by mass of oxalic acid, with the amount of oxalic acid being 16–20 times the mass of gel-aged particles G. Stir, heat to 50–70°C, and treat for 1–2 hours. Repeat this process at least 3 times. Filter to obtain particles H.

[0066] (6) Disperse particles H in deionized water, stir, wash, and filter. Repeat this process more than 6 times to raise the pH of the washing water to above 5.5, and obtain washed particles I.

[0067] (7) Disperse particle I in a low-carbon alcohol, stir for 24 hours, filter, and obtain particle J. The low-carbon alcohol is ethanol, isopropanol or n-butanol, and the amount of low-carbon alcohol is 15 to 25 times the mass of water-washed particle I.

[0068] (8) Particle J is dried using supercritical carbon dioxide and sieved using a standard sieve. Particles with a diameter between 10 and 150 micrometers are selected to obtain particle K. The supercritical carbon dioxide drying pressure is 10 to 20 MPa, the temperature is 40 to 120 °C, the carbon dioxide flow rate is 10 to 20 g of carbon dioxide per gram of particle J per hour, and the processing time is 2 to 4 hours.

[0069] (9) Calcining particles K by gradient heating: holding at 300-400℃ for 0.5-1.5 hours, 500-600℃ for 1-3 hours, and 600-700℃ for 3-6 hours respectively, with heating and cooling rates controlled at 0.5-1.5℃ / min; calcination is carried out in an air atmosphere, with an air flow rate of 0.2-2L per gram of particles K per hour; thus obtaining silica microspheres.

[0070] The obtained silica microspheres have a SiO2 mass fraction greater than 99.9%, an Al2O3 mass fraction less than 0.05%, and a Na2O mass fraction less than 0.01%.

[0071] The following detailed description is provided through specific embodiments.

[0072] Example 1

[0073] (1) Commercially available beta molecular sieves with a silicon-to-aluminum ratio (n(SiO2) / n(Al2O3), molar ratio) of 28 and a particle size of less than 1 micrometer were immersed in a 1% oxalic acid solution, heated to 60°C, stirred for 1 hour, and filtered. The above process was repeated twice. The acid-treated beta molecular sieves were washed with deionized water until the washing solution was nearly neutral (pH 6-7). The washed beta molecular sieves were dried at 120°C and calcined at 500°C for 2 hours to obtain modified beta molecular sieve powder, after which the silicon-to-aluminum ratio increased to 60.

[0074] (2) Select high-purity water glass with a modulus of 3.1 (silica mass fraction of 29%), add 4 times the mass of deionized water to prepare a water glass solution, add 5% of the total mass of beta molecular sieve modified powder to the water glass solution, put it into the mixed liquid A storage tank 1, stir thoroughly and continuously to make the material evenly mixed, and cool to -2℃ to obtain mixed liquid A.

[0075] Analytical grade sulfuric acid was diluted with deionized water to a mass fraction of 8%, stirred thoroughly and continuously, and cooled to -2°C to obtain sulfuric acid solution B.

[0076] Sodium bicarbonate was dissolved in deionized water to prepare an 8% (w / w) acid salt solution C, which was then stored in solution C storage tank 14.

[0077] (3) Mixture A flows into the first high-speed mixer 5 through the first metering pump 3 at a mass flow rate of 500 g / min; sulfuric acid solution B flows into the first high-speed mixer 5 through the second metering pump 4 at a mass flow rate of 200 g / min; high-speed stirring is performed to ensure that mixture A and sulfuric acid solution B are fully and continuously mixed in the first high-speed mixer 5 to obtain mixture D. The first high-speed mixer 5 is equipped with a cooling device to control the temperature of mixture D at -2℃.

[0078] (4) After the mixture D remains in the first high-speed mixer 5 for 5 minutes, it flows into the solution D storage tank 7 via the third metering pump 6 for temporary storage. The solution D storage tank 7 is equipped with a cooling device to control the temperature of the mixture D at -2℃. The mixture D flows into the second high-speed mixer 9 via the fourth metering pump 8 at a mass flow rate of 700 g / min. The sulfuric acid solution B (cooled to -2℃) in the second solution B storage tank 10 flows into the second high-speed mixer 9 via the fifth metering pump 11 at a mass flow rate of 70 g / min. The mixture D and the sulfuric acid solution B are mixed at high speed in the second high-speed mixer 9. The second high-speed mixer 9 is equipped with a cooling device to control the temperature of the resulting material d at -2℃.

[0079] The mixture d of solution D and sulfuric acid solution B is held for 15 seconds in the second high-speed mixer 9, and then flows into the third high-speed mixer 13 via the sixth metering pump 12 at a mass flow rate of 770 g / min. The acidic salt solution C flows into the third high-speed mixer 13 via the seventh metering pump 15 at a mass flow rate of 77 g / min, where the two are mixed at high speed. The third high-speed mixer 13 is equipped with a cooling device to control the temperature at -2°C.

[0080] After a residence time of 15 seconds in the third high-speed mixer 13, the mixture enters the atomizing nozzle 17 via the eighth metering pump 16. Under the shearing action of the mixed gas flow at 2 bar, atomized droplets E are produced. The flow rate of the eighth metering pump 16 is 847 g / min. The molar fraction of nitrogen in the mixed gas flow is 40%, and the molar fraction of carbon dioxide is 60%.

[0081] Use n-butanol with a water content of 5 wt% in container 21 to collect atomized droplets E. The n-butanol is continuously stirred and flowed to prevent droplets from agglomerating. After collecting the droplets for 10 minutes, stop spraying. Allow the droplets to be stirred in the n-butanol for 30 minutes to form gel particles F.

[0082] (5) Filter, collect gel particles F, and disperse them in an aqueous solution containing n-butanol (0%–5% by mass), stirring. The mass of the aqueous solution is 16 times the mass of gel particles F. Adjust the pH to 7–9 using dilute sulfuric acid, and heat to 65°C for 16 hours. Adjust the pH to 7–9 again using dilute sulfuric acid, and heat to 80°C for 4 hours.

[0083] The gel-aged particles G were collected by filtration. They were dispersed in a 0.5% oxalic acid aqueous solution (the mass of the oxalic acid aqueous solution was 16 times the mass of the particles F), stirred, heated to 65°C, and treated for 1 hour, then filtered. The above oxalic acid soaking process was repeated twice to obtain acid-treated particles H.

[0084] (6) Disperse the acid-treated particles H in deionized water (the mass of deionized water is 16 times the mass of particles H), stir, wash, and filter. Repeat this process at least 6 times until the pH of the washed water rises to above 5.5. This yields washed particles I.

[0085] (7) Disperse the water-washed particles I in isopropanol (the mass of isopropanol is 20 times the mass of the water-washed particles I) and stir for 24 hours. Filter to obtain alcohol bubble particles J.

[0086] (8) The alcohol-soaked granules J were dried using supercritical carbon dioxide to remove water and organic solvents from the granules. The supercritical carbon dioxide drying pressure was 20 MPa, the temperature was 100 °C, the carbon dioxide flow rate was 10 g of carbon dioxide per gram of granules J per hour, and the treatment time was 4 hours. The granules were then sieved to obtain dried granules K, with particles of 10–150 mesh.

[0087] (9) The dried particles K were calcined using a gradient heating method: 350℃ for 1 hour, 550℃ for 2 hours, and 750℃ for 4 hours, with the heating and cooling rates controlled at 1℃ / min. The air flow rate was 0.2L per gram of particles K per hour. The desired silica microspheres were then obtained.

[0088] The test results for specific surface area, pore volume, and silica content are shown in Table 1.

[0089] Example 2

[0090] Commercially available beta molecular sieves with a silicon-to-aluminum ratio (n(SiO2) / n(Al2O3), molar ratio) of 80 and a particle size of less than 1 micrometer were immersed in a 1% (w / w) oxalic acid solution, heated to 60°C, stirred for 1 hour, and filtered. This process was repeated twice. The acid-treated beta molecular sieves were washed with deionized water until the washing solution was nearly neutral (pH 6-7). The washed beta molecular sieves were dried at 120°C and calcined at 500°C for 2 hours to obtain modified beta molecular sieve powder, after which the silicon-to-aluminum ratio increased to 100.

[0091] Select high-purity water glass with a modulus of 3.5 (25% silica by mass), add 3.5 times the mass of deionized water to prepare a water glass solution, add 15% of the total mass of beta molecular sieve modified powder to the solution, put it into storage tank 1 of mixture A, stir thoroughly and continuously to make the material evenly mixed, and cool to -4℃ to obtain mixture A.

[0092] Analytical grade sulfuric acid was diluted with deionized water to a mass fraction of 10%, stirred thoroughly and continuously, and cooled to -4°C to obtain sulfuric acid solution B.

[0093] Ammonium bisulfate was dissolved in deionized water to prepare an acidic salt solution C with a mass concentration of 10%, which was then stored in solution C storage tank 14.

[0094] Mixture A flows into the first high-speed mixer 5 via the first metering pump 3 at a mass flow rate of 500 g / min; sulfuric acid solution B flows into the first high-speed mixer 5 via the second metering pump 4 at a mass flow rate of 250 g / min; high-speed stirring ensures that mixture A and sulfuric acid solution B are thoroughly and continuously mixed in the first high-speed mixer 5 to obtain mixture D. The first high-speed mixer 5 is equipped with a cooling device to control the temperature of mixture D to -4℃.

[0095] After being held in the first high-speed mixer 5 for 2 minutes, the mixture D flows into the solution D storage tank 7 via the third metering pump 6 for temporary storage. The solution D storage tank 7 is equipped with a cooling device to control the temperature of the mixture D at -4℃. The mixture D then flows into the second high-speed mixer 9 via the fourth metering pump 8 at a mass flow rate of 750 g / min. The sulfuric acid solution B in the second solution B storage tank 10 flows into the second high-speed mixer 9 via the fifth metering pump 11 at a mass flow rate of 75 g / min. The mixture D and the sulfuric acid solution B are mixed at high speed in the second high-speed mixer 9. The second high-speed mixer 9 is equipped with a cooling device to control the temperature of the resulting material d at -4℃.

[0096] The mixture d of solution D and sulfuric acid solution B is held in the second high-speed mixer 9 for 60 seconds, then flows into the third high-speed mixer 13 via the sixth metering pump 12 at a mass flow rate of 825 g / min. The acidic salt solution C flows into the third high-speed mixer 13 via the seventh metering pump 15 at a mass flow rate of 206 g / min, where the two are mixed at high speed. The third high-speed mixer 13 is equipped with a cooling device, controlling the temperature at -4°C.

[0097] After a residence time of 60 seconds in the third high-speed mixer 13, the mixture enters the atomizing nozzle 17 via the eighth metering pump 16. Under the shearing action of the mixed gas flow at 8 bar, atomized droplets E are produced. The flow rate of the eighth metering pump 16 is 1031 g / min. The molar fraction of nitrogen in the mixed gas flow is 80%, and the molar fraction of carbon dioxide is 20%.

[0098] Droplets E were collected using isobutanol with a water content of 7 wt%. The isobutanol was continuously stirred and flowed to prevent droplets from coalescing. After collecting the droplets for 10 minutes, the spraying was stopped. The droplets were then stirred in the isobutanol for 30 minutes to form gel particles F.

[0099] Filter and collect gel particles F, then disperse them in an aqueous solution containing n-butanol (0%–5% by mass) and stir. The mass of the aqueous solution should be 16 times the mass of gel particles F. Adjust the pH to 7–9 using dilute sulfuric acid and heat to 50°C for 16 hours. Adjust the pH to 7–9 again using dilute sulfuric acid and heat to 90°C for 4 hours.

[0100] The gel-aged particles G were collected by filtration. They were dispersed in a 0.5% oxalic acid aqueous solution (the mass of the oxalic acid aqueous solution was 20 times the mass of particle F), stirred, heated to 50°C, and treated for 2 hours, followed by filtration. The above oxalic acid soaking process was repeated twice to obtain acid-treated particles H.

[0101] Acid-treated particles H were dispersed in deionized water (the mass of deionized water was 16 times the mass of particles G), stirred, washed, and filtered. This process was repeated at least 6 times until the pH of the washed water rose above 5.5. This yielded water-washed particles I.

[0102] Water-washed particles I were dispersed in ethanol (ethanol mass was 20 times the mass of particles H) and stirred for 24 hours. After filtration, alcohol-bubble particles I were obtained.

[0103] Alcohol-containing granules I were dried using supercritical carbon dioxide to remove water and organic solvents. The supercritical carbon dioxide drying pressure was 10 MPa, the temperature was 120 °C, the carbon dioxide flow rate was 10 g of carbon dioxide per gram of granule I per hour, and the treatment time was 2 hours. The granules were then sieved using a standard sieve. Particles with a diameter between 10 and 150 micrometers were selected to obtain dried granules J.

[0104] The dried silica particles J were calcined using a gradient heating method: 350℃ for 1 hour, 550℃ for 2 hours, and 750℃ for 4 hours, with the heating and cooling rates controlled at 1℃ / min. The air flow rate was 2L of air per gram of silica particles per hour. This yielded the desired silica microspheres.

[0105] The test results for specific surface area, pore volume, and silica content are shown in Table 1.

[0106] Example 3

[0107] Select high-purity water glass with a modulus of 3.7, add 3 times the mass of deionized water, add 1% of the total mass of beta molecular sieve modified powder (processing method is the same as in Example 2) to the water glass solution, put it into storage tank 1 of mixture A, stir thoroughly and continuously to make the material mix evenly, and cool to 0°C to obtain mixture A.

[0108] Analytical grade sulfuric acid was diluted with deionized water to a mass fraction of 9%, stirred thoroughly and continuously, and cooled to 0°C to obtain sulfuric acid solution B.

[0109] Sodium bisulfate was dissolved in deionized water to prepare an acidic salt solution C with a mass concentration of 10%, which was then stored in solution C storage tank 14.

[0110] Mixture A flows into the first high-speed mixer 5 via the first metering pump 3 at a mass flow rate of 500 g / min; sulfuric acid solution B flows into the first high-speed mixer 5 via the second metering pump 4 at a mass flow rate of 220 g / min; high-speed stirring ensures that mixture A and sulfuric acid solution B are thoroughly and continuously mixed in the first high-speed mixer 5 to obtain mixture D. The first high-speed mixer 5 is equipped with a cooling device to control the temperature of mixture D at 0℃.

[0111] After the mixture D remains in the first high-speed mixer 5 for 10 minutes, it flows into the solution D storage tank 7 via the third metering pump 6 for temporary storage. The solution D storage tank 7 is equipped with a cooling device to control the temperature of the mixture D at 0°C. The mixture D then flows into the second high-speed mixer 9 via the fourth metering pump 8 at a mass flow rate of 720 g / min. The sulfuric acid solution B (cooled to 0°C) in the second solution B storage tank 10 flows into the second high-speed mixer 9 via the fifth metering pump 11 at a mass flow rate of 180 g / min. The mixture D and the sulfuric acid solution B are mixed at high speed in the second high-speed mixer 9. The second high-speed mixer 9 is equipped with a cooling device to control the temperature of the resulting material d at 0°C.

[0112] The mixture d of solution D and sulfuric acid solution B is held for 15 seconds in the second high-speed mixer 9, and then flows into the third high-speed mixer 13 via the sixth metering pump 12 at a mass flow rate of 900 g / min. The acidic salt solution C flows into the third high-speed mixer 13 via the seventh metering pump 15 at a mass flow rate of 225 g / min, where the two are mixed at high speed. The third high-speed mixer 13 is equipped with a cooling device to control the temperature at 0°C.

[0113] After a residence time of 15 seconds in the third high-speed mixer 13, the mixture enters the atomizing nozzle 17 via the eighth metering pump 16. Under the shearing action of the mixed gas flow at 3 bar, atomized droplets E are produced. The flow rate of the eighth metering pump 16 is 1125 g / min. The molar fraction of nitrogen in the mixed gas flow is 0%, and the molar fraction of carbon dioxide is 100%.

[0114] Place n-Butanol (5 wt% water content) in container 21 to collect droplets E. The n-Butanol is continuously stirred and flowed to prevent droplets from coalescing. After collecting the droplets for 10 minutes, stop spraying. Allow the droplets to be stirred in the n-Butanol for 30 minutes to form gel particles F.

[0115] Filter and collect gel particles F. Disperse them in an aqueous solution containing n-butanol (0%–5% by mass) and stir. The mass of deionized water is 16 times the mass of gel particles F. Adjust the pH to 7–9 using dilute sulfuric acid and heat to 70°C for 16 hours. Adjust the pH to 7–9 again using dilute sulfuric acid and heat to 90°C for 4 hours.

[0116] The gel-aged particles G were collected by filtration. They were dispersed in a 0.5% oxalic acid aqueous solution (the mass of the oxalic acid aqueous solution was 20 times the mass of particle G), stirred, heated to 70°C, and treated for 2 hours, followed by filtration. The above oxalic acid soaking process was repeated twice to obtain acid-treated particles H.

[0117] Acid-treated particles H were dispersed in deionized water (the mass of deionized water was 16 times the mass of particles G), stirred, washed, and filtered. This process was repeated at least 6 times until the pH of the washed water rose above 5.5. This yielded water-washed particles I.

[0118] Water-washed particles I were dispersed in isopropanol (the mass of isopropanol was 20 times the mass of particles I) and stirred for 24 hours. After filtration, alcohol bubble particles J were obtained.

[0119] The alcohol-containing granules J were dried using supercritical carbon dioxide to remove water and organic solvents. The supercritical carbon dioxide drying pressure was 15 MPa, the temperature was 110 °C, the carbon dioxide flow rate was 5 g of carbon dioxide per gram of granules J per hour, and the treatment time was 3 hours. The granules were then sieved to obtain dried granules K, with particles ranging from 10 to 150 mesh.

[0120] The dried silica microspheres K were calcined using a gradient heating method: 350℃ for 1 hour, 550℃ for 2 hours, and 750℃ for 4 hours, with the heating and cooling rates controlled at 1℃ / min. The air flow rate was 1L of air per gram of silica microspheres per hour. The desired silica microspheres were then obtained. The test results for specific surface area, pore volume, and silica content are shown in Table 1.

[0121] Example 4

[0122] Commercially available beta molecular sieves with a silicon-to-aluminum ratio (n(SiO2) / n(Al2O3), molar ratio) of 50 and a particle size of less than 1 micrometer were immersed in a 1% (w / w) oxalic acid solution, heated to 60°C, stirred for 1 hour, and filtered. This process was repeated twice. The acid-treated beta molecular sieves were washed with deionized water until the washing solution was nearly neutral (pH 6-7). The washed beta molecular sieves were dried at 120°C and calcined at 500°C for 2 hours to obtain modified beta molecular sieve powder, after which the silicon-to-aluminum ratio increased to 80.

[0123] Select high-purity water glass with a modulus of 3.5 (silica mass fraction of 27.6%), add 4 times the mass of deionized water, add 8% by mass of beta molecular sieve modified powder, put it into storage tank 1 of mixture A, stir thoroughly and continuously to make the materials evenly mixed, and cool to -3℃ to obtain mixture A.

[0124] Analytical grade sulfuric acid was diluted with deionized water to a mass fraction of 8%, stirred thoroughly and continuously, and cooled to -3°C to obtain sulfuric acid solution B.

[0125] Ammonium bicarbonate was dissolved in deionized water to prepare an acidic salt solution C with a mass concentration of 10%, which was then stored in solution C storage tank 14.

[0126] Mixture A flows into the first high-speed mixer 5 via the first metering pump 3 at a mass flow rate of 400 g / min; sulfuric acid solution B flows into the first high-speed mixer 5 via the second metering pump 4 at a mass flow rate of 200 g / min; high-speed stirring ensures that mixture A and sulfuric acid solution B are thoroughly and continuously mixed in the first high-speed mixer 5 to obtain mixture D. The first high-speed mixer 5 is equipped with a cooling device to control the temperature of mixture D at -3℃.

[0127] After being held in the first high-speed mixer 5 for 5 minutes, mixture D flows into solution D storage tank 7 via the third metering pump 6 for temporary storage. Solution D storage tank 7 is equipped with a cooling device to control the temperature of mixture D at -3℃. Mixture D then flows into the second high-speed mixer 9 via the fourth metering pump 8 at a mass flow rate of 600 g / min. Sulfuric acid solution B in the second solution B storage tank 10 flows into the second high-speed mixer 9 via the fifth metering pump 11 at a mass flow rate of 60 g / min. Mixture D and sulfuric acid solution B are mixed at high speed in the second high-speed mixer 9. The second high-speed mixer 9 is equipped with a cooling device to control the temperature at -3℃.

[0128] The mixture d of solution D and sulfuric acid solution B is held for 15 seconds in the second high-speed mixer 9, and then flows into the third high-speed mixer 13 via the sixth metering pump 12 at a mass flow rate of 660 g / min. The acidic salt solution C flows into the third high-speed mixer 13 via the seventh metering pump 15 at a mass flow rate of 140 g / min, where the two are mixed at high speed. The third high-speed mixer 13 is equipped with a cooling device to control the temperature at -3°C.

[0129] After a residence time of 15 seconds in the third high-speed mixer 13, the mixture enters the nozzle through the eighth metering pump 16, where it is sheared by a mixed gas flow of 6 bar to produce atomized droplets E. The flow rate of the eighth metering pump 16 is 800 g / min. The molar fraction of nitrogen and carbon dioxide in the mixed gas flow is 50%.

[0130] Use n-butanol with a water content of 1 wt% in container 21 to collect droplets E. The n-butanol is continuously stirred and flowed to prevent droplets from agglomerating. After collecting the droplets for 10 minutes, stop spraying. Let the droplets be stirred in the n-butanol for 30 minutes to form gel particles F.

[0131] Filter and collect gel particles F. Disperse them in an aqueous solution containing n-butanol (0%–5% by mass) and stir. The mass of deionized water is 16 times the mass of gel particles F. Adjust the pH to 7–9 using dilute sulfuric acid and heat to 60°C for 16 hours. Adjust the pH to 7–9 again using dilute sulfuric acid and heat to 85°C for 4 hours.

[0132] The gel-aged particles G were collected by filtration. They were dispersed in a 0.5% oxalic acid aqueous solution (the mass of the oxalic acid aqueous solution was 18 times the mass of particle G), stirred, heated to 60°C, and treated for 2 hours, followed by filtration. The above oxalic acid soaking process was repeated twice to obtain acid-treated particles H.

[0133] Acid-treated particles H were dispersed in deionized water (the mass of deionized water was 16 times the mass of particles H), stirred, washed, and filtered. This process was repeated at least 6 times until the pH of the washed water rose above 5.5. This yielded water-washed particles I.

[0134] Water-washed particles I were dispersed in isopropanol (the mass of isopropanol was 20 times the mass of particles I) and stirred for 24 hours. After filtration, alcohol bubble particles J were obtained.

[0135] The alcohol-containing granules J were dried using supercritical carbon dioxide to remove water and organic solvents. The supercritical carbon dioxide drying pressure was 15 MPa, the temperature was 100℃, the carbon dioxide flow rate was 2 g of carbon dioxide per gram of granules J per hour, and the treatment time was 4 hours. The granules were then sieved to obtain dried granules K, with particles ranging from 10 to 150 mesh.

[0136] The dried silica gel particles K were calcined using a gradient heating method: 350℃ for 1 hour, 550℃ for 2 hours, and 750℃ for 4 hours, with the heating and cooling rates controlled at 1℃ / min. The air flow rate was 0.5L per gram of silica gel particles per hour. This yielded the desired silica gel microspheres.

[0137] The test results for specific surface area, pore volume, and silica content are shown in Table 1.

[0138] Comparative Example 1

[0139] The process is the same as in Example 1, except that the organic solvent n-butanol used to collect the atomized droplets E in container 21 in step 4 is replaced with deionized water. The pore volume of the resulting silica microspheres shows a significant decrease. See Table 1 for details.

[0140] Comparative Example 2

[0141] The process is the same as in Example 1, except that step 7 is omitted. The washed silica gel particles I are directly dried and calcined with supercritical carbon dioxide. The pore volume of the resulting silica gel microspheres shows a significant decrease. See Table 1 for details.

[0142] Comparative Example 3

[0143] The process was the same as in Example 1, except that supercritical carbon dioxide drying in step 8 was replaced with conventional oven drying. The pore volume of the resulting silica microspheres decreased significantly. See Table 1 for details.

[0144] Comparative Example 4

[0145] For commercially available silicone microspheres, choose Grace's Davison 955 model silicone.

[0146] Table 1. Test data of silicone carrier physical properties

[0147]

[0148] The specific surface area, pore volume, SiO2 content, and wear rate in Table 1 were determined according to the standard "Silicone Test Method HG / T2765.5-2005".

[0149] As can be seen from the table above, the silica microspheres prepared in Examples 1-4 all have high specific surface area and maintain high pore volume.

[0150] In Comparative Example 1, after replacing the organic solvent n-butanol used to collect the atomized droplets E in Example 1 with deionized water, the pore volume of the resulting silica microspheres was significantly reduced, resulting in a smaller average pore size, which would affect the mass transfer performance inside the subsequent catalyst particles.

[0151] Comparative Examples 2 and 3 omitted a certain step of the present invention, both of which resulted in a significant decrease in the pore volume of the obtained silica microspheres. This demonstrates that each step of the present invention is crucial and works synergistically to produce silica microspheres with both high specific surface area and high pore volume.

[0152] Electron micrographs of the silica microspheres obtained in Example 1 are shown below. Figure 2 As can be seen from the figure, the silica microspheres prepared by the method of the present invention have a smooth surface. Electron micrographs of these microspheres and those of Comparative Example 4 (commercially available silica microspheres) are shown in the figure. Figure 3 By comparison, it can be seen that the silica microspheres prepared by the method of the present invention still exhibit a smooth surface when magnified 2000 times, while the surface of commercially available silica microspheres is still rough and uneven even when magnified 300 times. It can be seen that the silica microspheres prepared by the present invention have a smooth surface, good sphericity, good flowability, and good particle strength (a low wear rate indicates high strength).

[0153] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing silica microspheres as a catalyst support, characterized in that, Includes the following steps: (1) Add the beta molecular sieve modified powder to water glass solution and stir thoroughly to obtain mixture A; mix it with sulfuric acid solution B and stir at high speed to obtain mixture D; (2) The mixture D, which is pre-cooled to -4~0℃, is rapidly mixed with another sulfuric acid solution B, which is pre-cooled to -4~0℃. The resulting material d is rapidly mixed with the acid salt solution C. The resulting mixture e is atomized into droplets E under the shearing action of high-pressure airflow. The droplets are collected using flowing organic solvent, filtered, and then particles F are obtained. (3) Disperse particle F in an aqueous solution of n-butanol, and then perform aging treatment to obtain gel-aged particles G. Disperse them in an aqueous solution of oxalic acid, stir, heat to 50~70℃, treat for 1~2 hours, filter, and obtain particles H. (4) Disperse particles H in deionized water, stir, wash, and filter to raise the pH of the washing water to above 5.5 to obtain washed particles I; (5) Disperse particle I in low carbon alcohol, stir for 24 hours, filter to obtain particle J, dry with supercritical carbon dioxide, and sieve to select particles with a diameter between 10 and 150 micrometers to obtain particle K. (6) Particle K is calcined by gradient heating to obtain silica microspheres.

2. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, The beta molecular sieve modified powder mentioned in step (1) is prepared by the following method: Immerse the beta molecular sieve in oxalic acid solution, heat to 50-70℃, stir for 0.5-2 hours, and filter; repeat the above process several times; wash the obtained acid-treated beta molecular sieve until the washing solution is nearly neutral, then dry and calcine to obtain beta molecular sieve modified powder.

3. The method for preparing silica microspheres as a catalyst support according to claim 2, characterized in that, The beta molecular sieve is a commercially available beta molecular sieve with a silicon-to-aluminum ratio of 25-80:1 and a particle size of less than 1 micrometer. The oxalic acid solution has a mass concentration of 0.5% to 2%. The washed beta molecular sieves are dried at a temperature of 100~140℃, calcined at a temperature of 450~550℃, and calcined for 1~3 hours.

4. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, The water glass solution described in step (1) is prepared by adding high-purity water glass to deionized water, wherein the amount of deionized water is 3 to 4 times the mass of high-purity water glass. The high-purity water glass has a modulus of 3.1 to 3.7, a silicon dioxide mass fraction of 25% to 29%, and an impurity iron oxide mass fraction of less than 0.005% and an impurity aluminum oxide mass fraction of less than 0.07%.

5. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, The amount of beta molecular sieve modified powder in the mixture A is 1% to 15% of the mass of water glass; The sulfuric acid solution B has a mass fraction of 5% to 10%. The mass fraction of C in the acidic salt solution is 5%~10%; The acid salt used in acid salt solution C is selected from one or a mixture of sodium bicarbonate, ammonium bicarbonate, sodium bisulfate, and ammonium bisulfate.

6. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, In step (1), the mixture A and sulfuric acid solution B are continuously fed into the first high-speed mixer (5) with a cooling jacket at a mass flow ratio of 100:25 to 100:50 for high-speed mixing, and the mixing time is 2 to 10 minutes; the pH of the mixture D is 11 to 13.

7. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, In step (2), the mixture D and sulfuric acid solution B are continuously fed into the second high-speed mixer (9) at a mass flow ratio of 100:10 ~ 100:25 for rapid mixing. The mixing time is 15~60 seconds, and the pH of the mixed material is 10~12. The material d and the acid salt solution C are continuously fed into the third high-speed mixer (13) at a mass flow ratio of 100:10 ~ 100:25 for rapid mixing and residence for 15~60 seconds. The resulting mixture e has a pH of 8~10 and is sprayed out from the atomizing nozzle at the bottom of the third high-speed mixer (13). Under the shearing action of high-pressure airflow, atomized droplets E are produced.

8. The method for preparing silica microspheres as a catalyst support according to claim 7, characterized in that, The atomizing nozzle is a two-fluid nozzle, and the high-pressure airflow is a mixture of nitrogen and carbon dioxide gas at 2~8 bar, wherein the carbon dioxide content is 20%~100%. The organic solvent used to collect the atomized droplets E is aqueous n-butanol or isobutanol, wherein the mass fraction of water is 0.5% to 7%.

9. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, Step (3) The mass fraction of the aqueous solution of n-butanol is 0%~5%, and not 0; The aging process is as follows: first heat to 50~70℃ and treat for 15~18 hours, then heat to 80~90℃ and treat for 3~6 hours; The oxalic acid aqueous solution contains 0.1-1% oxalic acid by mass, and the amount of oxalic acid aqueous solution used is 16-20 times the mass of the gel aging particles G. The low-carbon alcohol mentioned in step (5) is ethanol, isopropanol or n-butanol, and the amount of low-carbon alcohol used is 15 to 25 times the mass of water-washed particles I. The supercritical carbon dioxide drying in step (5) is performed at a pressure of 10-20 MPa, a temperature of 40-120 °C, a carbon dioxide flow rate of 10-20 g carbon dioxide per gram of particles per hour, and a processing time of 2-4 hours.

10. The method for preparing silica microspheres as a catalyst support according to claim 1, characterized in that, The gradient heating method in step (6) is to stay at 300~400℃ for 0.5~1.5 hours, 500~600℃ for 1~3 hours, and 600~700℃ for 3~6 hours respectively, with the heating rate and cooling rate controlled at 0.5~1.5℃ / min; The roasting is carried out in an air atmosphere, with an air flow rate of 0.2 to 2 L of air per gram of particle K per hour; The silica microspheres have a SiO2 mass fraction greater than 99.9%, an Al2O3 mass fraction less than 0.05%, and a Na2O mass fraction less than 0.01%.

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