A method for preparing a porous microsphere hard template and application thereof

Abstract

This invention relates to the field of adsorption materials technology, and discloses a method for preparing porous microspheres using a hard template and its application. The invention employs an oil-in-water suspension polymerization method to prepare porous microspheres. Styrene is used as the monomer for the polymer microspheres; styrene has a low carbonization time, which is more energy-efficient. Divinylbenzene is used as the adhesive, and benzoyl peroxide is used as the initiator. The porous microsphere preparation method of this invention is a hard template method, which is simple, cost-controllable, environmentally friendly, and does not introduce additional pollution. It creates a large number of mesopores on the microsphere material, resulting in microspheres with a diameter of 0.45-0.9 mm and a BET value of 300-800 μm. 2 / g, toluene has an adsorption capacity of 14-27mg and a resistance of 17-20pa, exhibiting excellent adsorption and removal performance for pollutants in the air.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials technology, and in particular to a method for preparing porous microsphere hard templates and their applications. Background Technology

[0002] As semiconductors increasingly move towards miniaturized, high-density chips, higher demands are being placed on cleanroom technologies in the semiconductor industry. The substances requiring control fall into two main categories: particulate matter and aerosol pollutants (AMC). For particulate matter, high-efficiency particulate filters (HEPA) and ultra-high-efficiency particulate filters (ULPA) can be used for control. For aerosol pollutants, the current approach involves adding chemical filters to the main air handling unit (MAU).

[0003] The core component of a chemical filter is called the adsorption material, which commonly includes activated carbon, alumina, zeolite, silica gel, and ion exchange resins, most of which are porous materials. Among these, activated carbon and ion exchange resins are the most commonly used in chemical filters.

[0004] Activated carbon often uses biomass carbon because it is inexpensive and readily available. However, biomass carbon typically has lower strength and easily forms dust. Biomass is greatly affected by its growth environment and may carry toxic and harmful components from that environment, thus causing pollution. The activation process of activated carbon requires the use of chemicals such as acids, alkalis, and salts, and ion exchange resins also need to possess specific functional groups. These functional groups may detach during use, introducing new AMCs (Activated Carbon Mixtures) into the semiconductor plant and causing new pollution.

[0005] The preparation of porous carbon spheres using resins or carbohydrates is simple in composition and the process is controllable, making them ideal chemical filtration materials. However, to give activated carbon a porous structure, soft templates, such as toluene, n-heptane, and n-dodecane, are often used as pore-forming agents during the preparation process, or activators are added during the carbonization and activation of activated carbon. These preparation processes can easily cause environmental pollution and become a source of pollution for semiconductor plants. For example, Chinese patent CN103043649B uses chlorododecane as a pore-forming agent to prepare composite microspheres by combining styrene containing epoxy groups with sugar compounds, followed by high-temperature carbonization in an inert gas to obtain porous carbon spheres; this technology uses organic pore-forming agents, which pollute the environment. Chinese patent CN105174243B uses a soapless emulsion polymerization method to prepare polystyrene microspheres. The microspheres undergo Friedel-Crafts alkylation with halogenated hydrocarbons in the presence of a Lewis acid catalyst. The resulting particles are then precipitated using an organic solvent to form a porous structure. The microspheres are then carbonized, acid-washed, and dried under an inert atmosphere to obtain porous carbon spheres. The organic solvents used are toluene, acetone, ethanol, or tetrahydrofuran, which pose significant health and environmental hazards. Chinese patent CN111017923B uses a free radical-initiated catalytic method to prepare carbon microspheres. The microspheres are then placed in a nitrogen atmosphere at high temperature to obtain a primary carbonization product. After activation with hydroxides and acid washing, porous carbon is obtained. This method is more complex, the free radical initiation process is difficult to control, and the activation and acidification of activated carbon may introduce functional groups, making it unsuitable for use in semiconductor manufacturing facilities with high cleanliness requirements.

[0006] Template-based methods are the most effective way to control pore structure and adjust size, offering high specific surface area, regular channels, uniform pore size, and good stability. Hard templates do not decompose during polymer carbonization, thus maintaining a stable pore structure and minimizing pore collapse, which is beneficial for final adsorption performance. Hard templates are typically used in planar porous materials, or are pre-processed into a fixed shape before use; they are rarely used directly in the preparation of polymer microspheres through oil-in-water suspension polymerization. This is because nanotemplates easily break through the microsphere interface, escaping from the oil phase and dispersing in the aqueous phase, thus losing their template function. Therefore, selecting the right type of hard template and controlling the process are very challenging. Summary of the Invention

[0007] To address the aforementioned problems, one objective of this invention is to provide a method for preparing porous microsphere hard templates that is simple in process, cost-controllable, environmentally friendly, and does not cause additional pollution.

[0008] To achieve its objective, the present invention employs the following technical solution:

[0009] A method for preparing a porous microsphere hard template includes the following steps:

[0010] Step S2.1: Add the suspension stabilizer and aqueous phase polymerization inhibitor to deionized water at a mass ratio of 1:0.7-1.5 (preferably 1:0.7-0.9 or 0.7-0.8). The concentration of the suspension stabilizer in the mixed solution is 0.3-2wt%. Transfer the solution to a reaction vessel, maintain a stirring speed of 250-700 rpm, heat to 50-70℃ (preferably 55-65℃), and stir until homogeneous to obtain solution 1. The suspension stabilizer is selected from gelatin and PVC (polyvinyl alcohol), and the aqueous phase polymerization inhibitor is selected from methylene blue.

[0011] Step S2.2: Mix the nanoparticles with styrene, a 50-60 wt% divinylbenzene solution of adhesive, benzoyl peroxide initiator, and anhydrous ethanol at a mass ratio of 4-6:10-14:3-7:0.3-0.4:1-12, and mix at 50-55℃ until the nanoparticles are uniformly dispersed in the solution to obtain solution 2; the nanoparticles are nano-calcium carbonate particles or surface-treated nano-silica particles, wherein the surface-treated nano-silica particles are nano-silica that has been treated with KH570 and then surface-modified with styrene;

[0012] Preferably, when the nanoparticles are surface-treated nano-silica particles, the nanoparticles are mixed with styrene, a 50-60 wt% divinylbenzene solution of adhesive, benzoyl peroxide initiator, and anhydrous ethanol at a mass ratio of 5-6:10-14:5-7:0.3-0.4:2-8 or 5-6:10-14:5-7:0.3-0.4:2-5.

[0013] Preferably, when the nanoparticles are nano-calcium carbonate particles, the nanoparticles are mixed with styrene, a 50-60 wt% divinylbenzene solution as an adhesive, benzoyl peroxide as an initiator, and anhydrous ethanol in a mass ratio of 4-5:12-14:3-6:0.3-0.4:1-2.

[0014] Step S2.3: Transfer solution 2 into the reaction vessel of step S2.1, wherein the volume ratio of solution 1 to solution 2 is 6-10:1. React at 55-60℃ for 15-25 min, then at 80-85℃ for 3.5-4.5 h, and then at 90-95℃ for 1.5-2.5 h.

[0015] Step S2.4: Clean the particles obtained from the reaction in step S2.3 and dry them; then pre-activate them in air at 300-400℃ for 5.5-6.5h; then keep them at 600-800℃ (preferably 650-750℃) for 2.5-3.5h under inert gas protection to obtain microspheres;

[0016] Step S2.5: Immerse the microspheres obtained in step S2.4 in a template removal solution to remove the template, then wash with water until neutral to obtain porous microspheres. When the nanoparticles are surface-treated nano-silica particles, the template removal solution is a 1-5 mol / L sodium hydroxide or potassium hydroxide solution or a 20-40 wt% hydrofluoric acid solution. When the nanoparticles are nano-calcium carbonate particles, the template removal solution is an acid solution with pH ≤ 5 (preferably hydrochloric acid).

[0017] Step S2.2 uses 50-100W ultrasonic mixing.

[0018] In step S2.4, the temperature is increased to 600-800℃ at a heating rate of 5-10℃ / min.

[0019] Step S2.5: Soak the microspheres obtained in step S2.4 in template removal solution for 24-40 hours to remove the template.

[0020] In the above technical solution, the method for preparing the surface-treated nano-silica particles includes the following steps:

[0021] Step S1.1: Mix nano silica powder treated with KH570, sodium dodecyl sulfonate, styrene, and anhydrous ethanol at a mass ratio of 5-10:0.13-0.18:1.5-8.7:55-60 and carry out emulsification reaction. Mix thoroughly and evenly to obtain emulsion 1, and transfer it into the reaction vessel.

[0022] Step S1.2: Prepare a 0.14-0.2 wt% potassium persulfate aqueous solution, add it to emulsion 1 and mix to obtain a mixed solution. The amount of potassium persulfate in the mixed solution is added according to the mass ratio of solid potassium persulfate to styrene monomer solution in step S1.1 of 0.09-0.12:1.5-8.7 (preferably 0.1:1.5-4 or 0.1:1.5-2.0). React in a reactor at 75-85℃ in a closed container for 4-6 hours at a speed of 600-1000 rpm.

[0023] Step S1.3: After the reaction is complete, a demulsifier is added to break the emulsion. The precipitate is filtered, separated, and dried to obtain surface-treated nano-silica. Preferably, the demulsifier is a 7-13 wt% NaCl solution.

[0024] Preferably, in step S1.1, ultrasonic mixing with a power of 50–100 W is used;

[0025] The preferred mixture consists of nano-silica powder, sodium dodecyl sulfonate, styrene monomer solution, and anhydrous ethanol at a mass ratio of 5-8:0.13-0.16:1.5-5:55-58.

[0026] Further preferred materials include nano-silica powder, sodium dodecyl sulfonate, styrene monomer solution, and anhydrous ethanol, mixed at a mass ratio of 5-6:0.13-0.14:1.5-1.8:55-57.

[0027] Another object of the present invention is to provide porous microspheres prepared by the method described in any of the above-mentioned embodiments.

[0028] The porous microspheres have a diameter of 0.45-0.9 mm and a BET value of 300-800 μm. 2 / g.

[0029] Another object of the present invention is to provide the application of the above-described porous microspheres in the adsorption and removal of pollutants, preferably air pollutants.

[0030] Preferably, the application involves using porous microspheres to adsorb and remove pollutants from the air, and the pollutants in the air preferably include toluene.

[0031] This invention uses an oil-in-water suspension polymerization method to prepare porous microspheres. To prevent the viscous polymer from sticking together and to ensure that the monomers are suspended and dispersed in the aqueous phase as microdroplets, a suspension stabilizer needs to be added to the aqueous solution. Commonly used stabilizers include gelatin, polyvinyl alcohol, methylcellulose, and hydroxyethyl cellulose. In the embodiments of this invention, gelatin was used for the experiments.

[0032] Methylene blue is used as an aqueous polymerization inhibitor in the aqueous phase. Before the polymerization reaction, the aqueous solution is blue due to the presence of methylene blue. As the polymerization reaction proceeds, it gradually fades to white. When the amount of methylene blue is less than the range set in this invention, the time for the solution to turn white is shortened, which is not conducive to the stability of spherical particles. The final spheres have a large diameter range, and the proportion of spheres within the target diameter range, i.e., 0.45-0.9 mm in diameter, is reduced.

[0033] Styrene is the monomer that forms polymer spheres. Styrene has a low carbonization time, which is more energy-efficient. Divinylbenzene is used as an adhesive, and benzoyl peroxide is used as an initiator.

[0034] Porous materials prepared by soft template methods mostly have micropores, i.e., pores smaller than 2 nm, which have poor adsorption effects on macromolecules. Furthermore, soft templates have a narrow selection range, making precise morphological control difficult and prone to secondary pollution. The porous microsphere preparation method of this invention is a hard template method, which is simple, cost-effective, environmentally friendly, and does not introduce additional pollution. It creates a large number of mesopores on the microsphere material, resulting in microspheres with diameters of 0.45-0.9 mm and a molecular weight of 300-800 nm. 2 / g, toluene has an adsorption capacity of 14-27mg and a resistance of 17-20pa, exhibiting excellent adsorption and removal performance for pollutants in the air. Attached Figure Description

[0035] Figure 1 The images show resin spheres (A) before carbonization, black spherical activated carbon particles (B) obtained after high-temperature calcination, and electron micrographs (C) of the final product, activated carbon spheres.

[0036] Figure 2 The image shows the transparent resin microspheres (A) obtained in experimental group 4 and their electron microscope image (B). Detailed Implementation

[0037] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0038] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0039] Main materials and reagent sources:

[0040] Silane coupling agent KH-570 modified nano silica powder: that is, nano silica treated with KH570, with a particle size of 20nm, CAS number: 7631-86-9, which can be purchased directly from the market. In this study, the raw material was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd. (XFNANO), supplier product number XFI04.

[0041] Nano calcium carbonate powder: 20nm particle size, commercially available regular product, CAS number: 471-34-1.

[0042] Sodium dodecyl sulfonate: Chemical formula is C 12 H 25 SO3Na, CAS Registry Number 2386-53-0.

[0043] Styrene: Chemical formula C8H8, CAS Registry No. 100-42-5, a colorless, transparent, oily liquid. The styrene raw material used in this study has a purity of 99%.

[0044] Gelatin, CAS Registry No. 9000-70-8.

[0045] Methylene blue: chemical formula is C 16 H 18 ClN3S, CAS Registry Number 61-73-4.

[0046] Divinylbenzene: Chemical formula C 10 H 10 The CAS Registry Number is 1321-74-0. The divinylbenzene raw material used in this study has a purity of 55% and was commercially obtained.

[0047] Benzoyl peroxide: Chemical formula C 14 H 10O4, CAS Registry Number 94-36-0.

[0048] Example 1: Preparation of porous microspheres using nano-silica as a template

[0049] I. Nano-silica surface treatment:

[0050] Step S1.1: Mix the raw material nano silica powder (i.e., commercially available nano silica powder treated with KH570), sodium dodecyl sulfonate, styrene monomer solution, and anhydrous ethanol at a mass ratio of 5-10:0.13-0.18:1.5-8.65:55-60 and carry out an emulsification reaction. Mix evenly by ultrasonication at ≥50W to obtain emulsion 1, which is then transferred to a reaction vessel.

[0051] Step S1.2: Prepare an aqueous solution of potassium persulfate (K2S2O8) with a concentration of 0.14-0.2wt%, add it to emulsion 1 and mix to obtain a mixed solution. The amount of potassium persulfate in the mixed solution is added according to the mass ratio of solid potassium persulfate to styrene monomer solution in step S1.1 of 0.1:1.5-8.65. React in a reactor at 80℃ in a closed container for 4-6 hours at a speed of 600-1000 rpm.

[0052] Step S1.3: After the reaction is complete, add 10wt% NaCl solution to break the emulsion. After filtering, separating and drying the precipitate, it becomes surface-treated nano-silica.

[0053] The purpose of surface treatment of nano-silica is to reduce the surface energy of nano-silica, reduce agglomeration, increase the bonding strength between nano-silica and oil-phase polymers, and keep nano-silica stable in suspension polymerization, thereby forming nano-silica-polystyrene composite microspheres.

[0054] II. Preparation of porous microspheres

[0055] Follow these steps:

[0056] Step S2.1: Add gelatin (suspension stabilizer) and methylene blue (aqueous phase polymerization inhibitor) to deionized water at a mass ratio of 1:0.7-1.5. The concentration of gelatin in the mixed solution is 0.3-2wt%. Transfer the solution to a reaction vessel, maintain a stirring speed of 250-700rpm, set the temperature to 60℃, and stir until the temperature reaches 60℃ to obtain solution 1.

[0057] Step S2.2: The surface-treated nano-silica particles obtained in step S1.3 are mixed with styrene (liquid) (monomer to form polymer microspheres), divinylbenzene (liquid, purity 55%) (adhesive), and benzoyl peroxide (initiator) at a mass ratio of 5:10-14:5-7:0.3-0.4, and ultrasonically mixed at 50-55℃ and ≥50W until the nanoparticles are uniformly dispersed in the solution without obvious particulate matter or precipitation, thus obtaining solution 2. If solution 2 is viscous and has poor fluidity, anhydrous ethanol can be added to increase the fluidity of solution 2.

[0058] Step S2.3: Transfer solution 2 into the reaction vessel of step S2.1, wherein the volume ratio of solution 1 to solution 2 is 6-10:1 (the volume of solution 1 needs to be several times that of solution 2, and solution 2 is kept uniformly dispersed in solution 1). React at 55-60℃ for 20 min, then at 80-85℃ for 4 h, and then at 90-95℃ for 2 h.

[0059] Step S2.4: Clean and dry the particles obtained from the reaction in step S2.3. Then place them in a vacuum tube furnace and pre-activate them at 350℃ for 6 hours in an air environment; then, under N2 gas protection, heat them to 600-800℃ at a heating rate of 5-10℃ / min and hold for 3 hours to obtain microspheres.

[0060] Step S2.5: Immerse the microspheres obtained in step S2.4 in the template removal solution for at least 24 hours. After immersion, wash with deionized water until neutral to obtain the porous microspheres of the present invention. The template removal solution contains 1-5 mol / L sodium hydroxide or 20-40 wt% hydrofluoric acid.

[0061] The porous microspheres in Table 1-2 were prepared according to the above method. The experimental parameters for steps S1 and S2 are detailed in Table 1-3.

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066]

[0067] In step 2.1, the volume of deionized water is 200 ml.

[0068] Table 3

[0069]

[0070] The burn-off ratio refers to the weight loss of the prepared microspheres after combustion. The burn-off ratio reflects the number of pores on the microspheres from one perspective.

[0071] The template removal solution for experimental groups 1-8 was a 5 mol / L sodium hydroxide solution.

[0072] III. Weight of microspheres with different diameters

[0073] The porous microspheres prepared in experimental groups 1-8 were graded by mesh sieve to detect the weight of microspheres of different diameters. The results are shown in Table 4.

[0074] Table 4. Weight (g) of microspheres with different diameters

[0075]

[0076]

[0077] Microspheres with a diameter of 0.45-0.9 mm can be used for gas adsorption and are the target product of this invention. Table 3 shows that experimental groups 1-3 and 6 have high yields of 0.45-0.9 mm microspheres, while experimental groups 5 and 7 have relatively low yields of the target product. The morphology of the particulate matter product obtained in step S2.3 of experimental group 6 is shown in the figure. Figure 1 As shown in Figure A, after high-temperature calcination in step S2.4, black spherical activated carbon particles (such as...) are obtained. Figure 1 As shown in Figure B), the electron microscope image of the final product, activated carbon spheres, is as follows. Figure 1 As shown in C.

[0078] If surface modification is not performed in step S1 (experimental group 8), and nano-silica is used directly, the nano-silica separates from the oil phase (styrene) and the target product cannot be formed.

[0079] When the amount of styrene used for modification in step S1.1 is less than 1.5g, the nano-silica and the oil phase separate, and the target product cannot be formed. Figure 2 (AB). When the amount of styrene used for modification in step S1.1 is greater than 8.65, the diameter of the small balls is larger, the stirring speed is too fast, the out-of-roundness is obvious, and the BET is larger.

[0080] IV. Performance Testing

[0081] The BET value index was determined according to GB / T 19587-2017 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method".

[0082] The toluene adsorption capacity and resistance index were tested using the ISO 10121-1 standard, "Test methods for performance evaluation of gas phase air purification materials and apparatus for general ventilation - Part 1: gas phase air purification materials". The air flow rate was 23.5 L / min, the test column diameter was 50 mm, and the sample thickness was 3 mm.

[0083] Testing methods for downstream pollutants (testing experimental group 6 and comparative examples 1-2):

[0084] Place 5g of sample into a 50mm diameter test column, set the gas flow rate to 4L / min, and sample upstream and downstream of the test column at 2L / min. Use deionized water for sampling and test the ions in the sampled water using ion chromatography.

[0085] The flow rate was set to 2 L / min. Samples were taken upstream and downstream of the test column at a flow rate of 0.5 L / min using TENX tubes. The TENX sampling tubes were then tested using gas chromatography.

[0086] The test results are shown in Table 5:

[0087] Table 5

[0088]

[0089]

[0090] In Table 5, Comparative Examples 1 and 2 are different brands of commercially available coconut shell activated carbon used for TVOC removal, with particle sizes ranging from 0.5 to 1 mm. The pH of Comparative Example 1 is 6.06, and the pH of Comparative Example 2 is 6.29. The pH test method is as follows: the sample is placed in deionized water, boiled for 30 minutes, filtered, cooled, and the pH value of the filtered solution is tested.

[0091] As can be seen from Table 5, the experimental group has lower resistance than the control group. Within the same particle size range, spherical activated carbon has lower resistance and can save energy.

[0092] Downstream pollutants were tested on the products of experimental group 6 and the comparative example. The results showed that the downstream acid ions, metal ions and TVOC content of the product of experimental group 6 were lower than those of the comparative example, and its pollution to the environment was less when used.

[0093] Example 2: Optimization Experiment at Different Carbonization Temperatures

[0094] Before determining the final experimental scheme, we studied the effect of different carbonization temperatures on the product. We conducted a comparative experiment on the particulate matter product obtained from step S2.3 of experimental group 3 in Example 1 at different carbonization temperatures:

[0095] The particles obtained from step S2.3 were cleaned and dried. They were then placed in a vacuum tube furnace and pre-activated at 350℃ for 6 hours in air. Next, under N2 gas protection, the temperature was increased to the set carbonization temperature at a rate of 10℃ / min and held for 3 hours to obtain the final product, microspheres. Their BET (Biological Emission Test) was measured, and the results are shown in Table 6.

[0096] Table 6

[0097] Carbonization temperature ℃ 600 650 700 750 800 <![CDATA[BET(m 2 / g)]]> 285 437 491 304 291

[0098] As can be seen from Table 6, the product has the largest BET at 700℃, which is the optimal carbonization temperature.

[0099] Example 3: Preparation of porous microspheres using nano-calcium carbonate as a template

[0100] Step S1 of Example 1 is not required. Step S2 is performed directly using purchased nano-calcium carbonate powder, which is the same as step S2 in Example 1, except that: 1. The surface-treated nano-silica particles in step S2.2 are replaced with nano-calcium carbonate powder; 2. The template removal solution in step S2.5 is selected from an acidic solution with a pH ≤ 5. A total of porous microspheres in experimental groups 9-15 were prepared. The experimental parameters for each step are shown in Tables 7-8.

[0101] Table 7

[0102]

[0103]

[0104] Table 8

[0105]

[0106] The template removal solution for experimental groups 9-15 was HCl with pH=2.

[0107] The products of experimental groups 9-16 were tested according to the detection method in Example 1, and the results are shown in Tables 9-10:

[0108] Table 9. Weight (g) of microspheres with different diameters

[0109]

[0110] Table 10

[0111]

[0112] As shown in Table 7-10, experimental groups 12 and 13 could not form small ball products due to the raw material ratio, and instead obtained lumpy products, thus failing to obtain the target product.

[0113] The products from experimental groups 9-11 and 14-15 exhibited lower resistance than the coconut shell activated carbon in Comparative Examples 1 and 2 of Example 1. Within the same particle size range, spherical activated carbon also showed lower resistance, resulting in energy savings. Furthermore, the porous microspheres obtained in experimental group 15, compared to Comparative Examples 1 and 2 of Example 1, showed lower downstream pollutant content in downstream acidic ions, metal ions, and TVOC, indicating less environmental pollution during use.

Claims

1. A method for preparing a porous microsphere hard template, characterized in that, Includes the following steps: Step S1.1: Mix nano silica powder treated with KH570, sodium dodecyl sulfonate, styrene, and anhydrous ethanol at a mass ratio of 5-10:0.13-0.18:1.5-8.7:55-60 and carry out emulsification reaction. Mix thoroughly and evenly to obtain emulsion 1, and transfer it into the reaction vessel. Step S1.2: Prepare a 0.14-0.2wt% potassium persulfate aqueous solution, add it to emulsion 1 and mix to obtain a mixed solution. The amount of potassium persulfate in the mixed solution is added according to the mass ratio of solid potassium persulfate to styrene monomer in step S1.1 of 0.09-0.12:1.5-8.

7. React in a reactor at 75-85℃ in a closed container for 4-6 hours at a speed of 600-1000 rpm. Step S1.3: After the reaction is complete, add a demulsifier to demulsify, filter and separate the precipitate, and dry it to obtain the surface-treated nano-silica. Step S2.1: Add the suspension stabilizer and aqueous phase polymerization inhibitor to deionized water at a mass ratio of 1:0.7-1.

5. The concentration of the suspension stabilizer in the mixed solution is 0.3-2wt%. Transfer the solution to a reaction vessel, maintain a stirring speed of 250-700 rpm, heat to 50-70℃, and stir until homogeneous to obtain solution 1. The suspension stabilizer is gelatin, and the aqueous phase polymerization inhibitor is selected from methylene blue. Step S2.2: Mix the nanoparticles with styrene, a 50-60 wt% divinylbenzene solution of adhesive, benzoyl peroxide initiator, and anhydrous ethanol at a mass ratio of 5-6:10-14:5-7:0.3-0.4:2-8, and mix at 50-55℃ until the nanoparticles are uniformly dispersed in the solution to obtain solution 2; the nanoparticles are the surface-treated nano-silica particles obtained in step S1.3; Step S2.3: Transfer solution 2 into the reaction vessel of step S2.1, wherein the volume ratio of solution 1 to solution 2 is 6-10:

1. React at 55-60℃ for 15-25 min, then at 80-85℃ for 3.5-4.5 h, and then at 90-95℃ for 1.5-2.5 h. Step S2.4: Clean the particles obtained from the reaction in step S2.3, dry them, and then pre-activate them in air at 300-400℃ for 5.5-6.5h; then keep them at 600-800℃ for 2.5-3.5h under inert gas protection to obtain microspheres. Step S2.5: Immerse the microspheres obtained in step S2.4 in a template removal solution to remove the template, then wash with water until neutral to obtain porous microspheres; the template removal solution is a 1-5 mol / L sodium hydroxide or potassium hydroxide solution or a 20-40 wt% hydrofluoric acid solution; the diameter of the porous microspheres is 0.45-0.9 mm, and the molecular weight is 300-800 μm. 2 / g.

2. A method for preparing a porous microsphere hard template, characterized in that, Includes the following steps: Step S2.1: Add the suspension stabilizer and aqueous phase polymerization inhibitor to deionized water at a mass ratio of 1:0.7-1.

5. The concentration of the suspension stabilizer in the mixed solution is 0.3-2wt%. Transfer the solution to a reaction vessel, maintain a stirring speed of 250-700 rpm, heat to 50-70℃, and stir until homogeneous to obtain solution 1. The suspension stabilizer is gelatin, and the aqueous phase polymerization inhibitor is selected from methylene blue. Step S2.2: Mix the nanoparticles with styrene, a 50-60 wt% divinylbenzene solution of adhesive, benzoyl peroxide initiator, and anhydrous ethanol at a mass ratio of 4-5:12-14:3-6:0.3-0.4:1-2, and mix at 50-55℃ until the nanoparticles are uniformly dispersed in the solution to obtain solution 2; the nanoparticles are nano-calcium carbonate particles; Step S2.3: Transfer solution 2 into the reaction vessel of step S2.1, wherein the volume ratio of solution 1 to solution 2 is 6-10:

1. React at 55-60℃ for 15-25 min, then at 80-85℃ for 3.5-4.5 h, and then at 90-95℃ for 1.5-2.5 h. Step S2.4: Clean the particles obtained from the reaction in step S2.3, dry them, and then pre-activate them in air at 300-400℃ for 5.5-6.5h; then keep them at 600-800℃ for 2.5-3.5h under inert gas protection to obtain microspheres. Step S2.5: Immerse the microspheres obtained in step S2.4 in a template removal solution to remove the template, then wash with water until neutral to obtain porous microspheres; the template removal solution is an acidic solution with pH ≤ 5; the diameter of the porous microspheres is 0.45-0.9 mm, and the molecular weight is 300-800 μm. 2 / g.

3. The method according to claim 1 or 2, characterized in that: Step S2.2 uses 50-100W ultrasonic mixing.

4. The method according to claim 1 or 2, characterized in that: In step S2.4, the temperature is increased to 600-800℃ at a heating rate of 5-10℃ / min.

5. The method of claim 1 or 2, wherein: Step S2.5: Soak the microspheres obtained in step S2.4 in template removal solution for 24-40 hours to remove the template.

6. The method of claim 1, wherein: The demulsifier is a 7-13 wt% NaCl solution.

7. The method of claim 1, wherein: In step S1.1, ultrasonic mixing with a power of 50-100W is used; Nano silica powder, sodium dodecyl sulfonate, styrene monomer solution, and anhydrous ethanol are mixed in a mass ratio of 5-8:0.13-0.16:1.5-5:55-58.

8. Porous microspheres prepared by the method according to any one of claims 1 to 7.

9. The application of the porous microspheres according to claim 8 in the adsorption and removal of air pollutants.

10. Use according to claim 9, characterized in that: The application involves using porous microspheres to adsorb and remove air pollutants, including toluene.

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