A method for preparing aluminum silicate-based nanoflower porous material

Abstract

The present invention discloses a method for preparing an aluminum silicate-based nanoflower porous material. The prepared product of the present invention exhibits a special nanoflower-like morphology, has fibrous open pores, has highly open space and effective utilization of active sites, and the like. The present invention uses aluminum salts and TEOS as raw materials and prepares a novel catalyst carrier material with a nanoflower-like structure by a hydrothermal method. Due to the large pore volume between its nanoflower petals and the excellent directly accessible interface structure, the surface of its petal structure can well disperse various catalytic active sites. The preparation process of the present invention is simple and controllable, and the obtained product has rich pore types and high specific surface area, which is convenient for industrial preparation. At the same time, the obtained product of the present invention is convenient for further processing to prepare a catalyst with extremely excellent performance.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation and porous material preparation, and in particular relates to a method for preparing an aluminum silicate-based nanoflower porous material. Background Art

[0002] Aluminum silicate is an important inorganic material with multiple uses. Due to its unique physical and chemical properties, it not only has a wide range of applications but also occupies a key position in modern industry. Aluminum silicate usually appears as colorless crystals or white to gray powder and is insoluble in water. Aluminum silicate has low thermal conductivity, excellent thermal stability, and good chemical stability, making it very important for applications in coatings and paints, the paper industry, refractories, and catalyst carrier materials. However, with the changing times and the rapid development of science and technology, traditional aluminum silicate materials have certain limitations in industrial applications, especially in the understanding of some special requirements such as material specific surface area and pore size, such as in the field of VOCs control. To meet the special needs of these fields, aluminum silicate nanoflowers with large pore volume and excellent directly accessible interface structure have emerged.

[0003] Aluminum silicate nanoflowers are made from aluminum salts and TEOS via a hydrothermal method. Due to their unique interface structure, the petal structure of the aluminum silicate nanoflowers allows for the excellent dispersion of various catalytically active sites.

[0004] Existing methods for preparing aluminum silicate include: preparing amorphous aluminum silicate by co-precipitation, preparing aluminum silicate carrier by fractional precipitation, and preparing nano aluminum silicate by chemical precipitation or microwave drying. However, the products produced by these methods are not applicable in certain special fields, that is, the specific surface area is relatively small, the pore structure types are insufficient, and it is difficult to form nanoflowers with open fibrous pores, etc. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing an aluminum silicate-based nanoflower porous material. The prepared product of the present invention exhibits a special nanoflower-like morphology, has fibrous open pores, has highly open space and effective utilization of active sites, etc.

[0006] The aluminum silicate nanoflowers of the present invention exhibit a special nanoflower-like morphology, have fibrous open pores, and have the characteristics of highly open space and effective utilization of active sites.

[0007] The present invention provides a method for preparing an aluminum silicate-based nanoflower porous material, comprising the following steps:

[0008] Step 1: A water-soluble aluminum salt, benzoic acid, and polyvinyl pyrrolidone are dissolved in solvent A, followed by a hydrothermal reaction. The resulting precipitate is washed and dried to obtain aluminum-containing bipyramidal organic metal nanoparticles; the solvent A comprises ethanol, acetone, nitric acid, and water;

[0009] Step 2: placing the product obtained in step 1 into a tube furnace for calcination, and obtaining an aluminum-containing organic metal framework after calcination;

[0010] Step 3: Add the product obtained in step 2 and urea to solvent B and mix them evenly, then add organic silicate and carry out a hydrothermal reaction; the obtained product is washed, dried, and calcined to obtain aluminum silicate nanoflowers; the solvent B is composed of methanol and water.

[0011] The preparation method of the invention is simple and easy to implement and operates under mild conditions.

[0012] In step 1 of the present invention, the water-soluble aluminum salt is selected from at least one of aluminum nitrate, aluminum sulfate, and aluminum silicate, preferably aluminum nitrate. In industrial applications, a hydrate of aluminum nitrate, such as aluminum nitrate nonahydrate, can be used.

[0013] In step 1 of the present invention, the benzoic acid is selected from at least one of trimesic acid, p-benzoic acid, o-benzoic acid, and m-benzoic acid, preferably trimesic acid.

[0014] As a preferred embodiment, aluminum nitrate nonahydrate, trimesic acid, and polyvinyl pyrrolidone are dissolved in solvent A, followed by a hydrothermal reaction. The resulting precipitate is washed three times with ethanol and centrifuged to dry. Furthermore, in step 1, the mass ratio of trimesic acid, aluminum nitrate nonahydrate, and polyvinyl pyrrolidone is 1:2-4:6-8, and the volume ratio of 32.5% nitric acid, water, ethanol, and acetone is 1:2-4:7-9:7-9.

[0015] Furthermore, in step 1, the mass ratio of trimesic acid, aluminum nitrate nonahydrate, and polyvinyl pyrrolidone is 1:2.5-3.5:6-7.0.

[0016] Furthermore, in step 1, the volume ratio of nitric acid with a volume concentration of 32.5%, water, ethanol, and acetone is: 1:2.5~3.5:7~8:7~8.

[0017] Furthermore, the hydrothermal reaction temperature in step 1 is 140-160°C and the reaction time is 40-50 hours. A temperature that is too high or too low will result in the inability to form bipyramidal nanoparticles after step 1, and further, the inability to form expanded aluminum silicate nanoflowers after step 3.

[0018] Furthermore, the drying temperature in step 1 is 90-100°C.

[0019] Furthermore, the calcination temperature in the tubular furnace in step 2 is 440-550°C, preferably 475-525°C, for 1-2 hours. Excessively high temperatures can lead to the formation of compacted Al2O3, which in turn affects the subsequent expansion of the aluminum silicate nanoflowers. Excessively low temperatures can lead to the formation of transitional pore structures, which also prevent the expansion of the aluminum silicate nanoflowers.

[0020] Furthermore, in step 3, urea is added to solvent B, wherein the mass ratio of urea to solvent B is 1:200~300, preferably 1:200~220. Without adding urea, fully expanded aluminum silicate nanoflowers cannot be formed after performing all steps.

[0021] Furthermore, in step 3, the organosilicate is selected from at least one of tetraethyl orthosilicate, methyl silicate, phenyl silicate, and a silane coupling agent. The mass ratio of the organosilicate to solvent B is 1:8-12. If the organosilicate content is too high, silica balls may form after all steps, hindering the expansion of the aluminum silicate nanoflowers. If the silicate content is too low, complete aluminum silicate nanoflowers may not form after all steps.

[0022] Furthermore, the hydrothermal reaction temperature in step 3 is 160-220°C, preferably 185-205°C, and the reaction time is 14-16 hours. In industrial applications, after the hydrothermal reaction is completed, the resulting aluminum silicate nanoflowers are washed at least twice with ethanol and dried. Drying methods include centrifugal drying.

[0023] In step 3, the calcination temperature is 525-575° C., the calcination time is 30-12 min, preferably 45-90 min, and the calcination atmosphere is an oxygen-containing atmosphere, preferably an air atmosphere.

[0024] The advantages and positive effects of the present invention are:

[0025] 1. The aluminum silicate nanoflowers of the present invention exhibit a unique nanoflower-like morphology with fibrous open pores, which promotes the dispersion of active metal species components and improves the catalytic reaction efficiency in the hydrogenation of carbon dioxide to methanol.

[0026] 2. The present invention obtains aluminum silicate nanoflowers with large specific surface area, nanoflower-like morphology and fibrous open pores through the synergistic effect of process and temperature, material ratio and reaction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the scanning electron microscope image of sample 1;

[0028] Figure 2 is the scanning electron microscope image of sample 2;

[0029] Figure 3 is the scanning electron microscope image of sample 3;

[0030] Figure 4 is the scanning electron microscope image of sample 4;

[0031] Figure 5 is the scanning electron microscope image of sample 5;

[0032] Figure 6 is the scanning electron microscope image of sample 6;

[0033] Figure 7 is the scanning electron microscope image of sample 7;

[0034] Figure 8 is the scanning electron microscope image of sample 8;

[0035] Figure 9 is the scanning electron microscope image of sample 9;

[0036] Figure 10 is the scanning electron microscope image of sample 10;

[0037] Figure 11 is the scanning electron microscope image of sample 11;

[0038] Figure 12 is a scanning electron microscope image of sample 12;

[0039] Figure 13 is the scanning electron microscope image of sample 13;

[0040] Figure 14 is a scanning electron microscope image of sample 14;

[0041] Figure 15 is the scanning electron microscope image of sample 15;

[0042] Figure 16 is a scanning electron microscope image of sample 16;

[0043] Figure 17 is the scanning electron microscope image of sample 17;

[0044] Figure 18 is a scanning electron microscope image of sample 18;

[0045] Figure 19 is the scanning electron microscope image of sample 19;

[0046] Figure 20 is a scanning electron microscope image of sample 20;

[0047] Figure 21 is the scanning electron microscope image of sample 21;

[0048] Figure 22 This is the scanning electron microscope image of sample 22. DETAILED DESCRIPTION

[0049] The present invention is described in detail below with reference to specific embodiments, but is by no means intended to limit the present invention. Any features, such as preparation methods, materials, structures, or composition ratios, that are not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0050] The following examples will help those skilled in the art further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several variations and improvements without departing from the scope of the present invention. These variations and improvements are all within the scope of protection of the present invention.

[0051] The practice of the present invention can employ conventional techniques of polymer chemistry within the skill of the art. In the following examples, efforts have been made to ensure accuracy with respect to numbers used (including amounts, temperatures, reaction times, etc.), but some experimental errors and deviations should be accounted for.

[0052] In this embodiment, all reagents used are commercially available reagents.

[0053] Example 1: This example provides a method for preparing aluminum silicate nanoflowers, comprising the following steps:

[0054] Step 1: 2875 mg of aluminum nitrate nonahydrate, 1000 mg of trimesic acid, and 6375 mg of polyvinyl pyrrolidone were dissolved in a mixture of 93.75 mL of ethanol, 93.75 mL of acetone, 12.5 mL of 32.5% nitric acid, and 37.5 mL of water, and the mixture was fully ultrasonically dispersed. The mixture was transferred to a Teflon-lined reactor and hydrothermally precipitated at 150°C for 45 hours to obtain a relatively dense precipitate. The precipitate was washed three times with ethanol and centrifuged to dry at 95°C. The dried product was observed under a scanning electron microscope to be bipyramidal solid nanoparticles (such as Figure 1 As shown), recorded as sample 1;

[0055] Step 2: 40 mg of bipyramidal nanoparticles were placed in a tube furnace and calcined at 500 °C in air atmosphere at a heating rate of 1 °C / min for 1 h to obtain active transition state alumina. The bipyramidal hollow nanoparticles (such as Figure 2 As shown), recorded as sample 2;

[0056] Step 3: The active transition alumina prepared in step 2 and 120 mg of urea were ultrasonically dispersed in a mixture of 20 mL of methanol and 10 mL of deionized water. A mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:10 was added and fully ultrasonically dispersed. The mixture was transferred to a 190°C autoclave for hydrothermal reaction for 15 hours. The precipitate was washed three times with ethanol and centrifuged to dry. The dried product was then placed in a tubular furnace and calcined at 550°C in an air atmosphere at a heating rate of 1°C / min for 1 hour. At this time, relatively pure aluminum silicate nanoflower particles (such as Figure 3 as shown), recorded as sample 3.

[0057] Example 2: This example provides a method for preparing aluminum silicate nanoflowers, comprising the following steps:

[0058] Step 1: 2875 mg of aluminum nitrate nonahydrate, 1000 mg of trimesic acid, and 6375 mg of polyvinyl pyrrolidone were dissolved in a mixture of 93.75 mL of ethanol, 93.75 mL of acetone, 12.5 mL of 32.5% nitric acid, and 37.5 mL of water, and the mixture was fully ultrasonically dispersed. The mixture was transferred to a Teflon-lined reactor and hydrothermally precipitated at 150°C for 45 hours to obtain a relatively dense precipitate. The precipitate was washed three times with ethanol and centrifuged to dry at 95°C. The dried product was observed under a scanning electron microscope to be bipyramidal solid nanoparticles (such as Figure 1 As shown), recorded as sample 1;

[0059] Step 2: 40 mg of bipyramidal nanoparticles were placed in a tube furnace and calcined at 450 °C in air atmosphere at a heating rate of 1 °C / min for 1 h to obtain active transition state alumina. The hollow bipyramidal nanoparticles (such as Figure 4 As shown), recorded as sample 4;

[0060] Step 3: The active transition alumina prepared in step 2 and 120 mg of urea were ultrasonically dispersed in a mixture of 20 mL of methanol and 10 mL of deionized water. A mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:10 was added and fully ultrasonically dispersed. The mixture was transferred to a 190°C autoclave for hydrothermal reaction for 15 hours. The precipitate was washed three times with ethanol and centrifuged to dry. The dried product was then placed in a tubular furnace and calcined at 550°C in an air atmosphere at a heating rate of 1°C / min for 1 hour. At this time, relatively pure aluminum silicate nanoflower particles (such as Figure 5 as shown), recorded as sample 5.

[0061] Example 3: This example provides a method for preparing aluminum silicate nanoflowers, comprising the following steps:

[0062] Step 1: 2875 mg of aluminum nitrate nonahydrate, 1000 mg of trimesic acid, and 6375 mg of polyvinyl pyrrolidone were dissolved in a mixture of 93.75 mL of ethanol, 93.75 mL of acetone, 12.5 mL of 32.5% nitric acid, and 37.5 mL of water, and the mixture was fully ultrasonically dispersed. The mixture was transferred to a Teflon-lined reactor and hydrothermally precipitated at 150°C for 45 hours to obtain a relatively dense precipitate. The precipitate was washed three times with ethanol and centrifuged to dry at 95°C. The dried product was observed under a scanning electron microscope to be bipyramidal solid nanoparticles (such as Figure 1 As shown), recorded as sample 1;

[0063] Step 2: 40 mg of bipyramidal nanoparticles were placed in a tube furnace and calcined at 500 °C in air atmosphere at a heating rate of 1 °C / min for 1 h to obtain active transition state alumina. The bipyramidal hollow nanoparticles (such as Figure 2 As shown), recorded as sample 2;

[0064] Step 3: The active transition alumina prepared in step 2 and 120 mg of urea were ultrasonically dispersed in a mixture of 20 mL of methanol and 10 mL of deionized water. A mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:8 was added and fully ultrasonically dispersed. The mixture was transferred to a 190°C autoclave for hydrothermal reaction for 15 hours. The precipitate was washed three times with ethanol and centrifuged to dry. The dried product was then placed in a tubular furnace and calcined at 550°C in an air atmosphere at a heating rate of 1°C / min for 1 hour. At this time, relatively pure aluminum silicate nanoflower particles (such as Figure 6 as shown), recorded as sample 6.

[0065] Example 4: This example provides a method for preparing aluminum silicate nanoflowers, comprising the following steps:

[0066] Step 1: 2875 mg of aluminum nitrate nonahydrate, 1000 mg of trimesic acid, and 6375 mg of polyvinyl pyrrolidone were dissolved in a mixture of 93.75 mL of ethanol, 93.75 mL of acetone, 12.5 mL of 32.5% nitric acid, and 37.5 mL of water, and the mixture was fully ultrasonically dispersed. The mixture was transferred to a Teflon-lined reactor and hydrothermally precipitated at 150°C for 45 hours to obtain a relatively dense precipitate. The precipitate was washed three times with ethanol and centrifuged to dry at 95°C. The dried product was observed under a scanning electron microscope to be bipyramidal solid nanoparticles (such as Figure 1 As shown), recorded as sample 1;

[0067] Step 2: 40 mg of bipyramidal nanoparticles were placed in a tube furnace and calcined at 500 °C in air atmosphere at a heating rate of 1 °C / min for 1 h to obtain active transition state alumina. The bipyramidal hollow nanoparticles (such as Figure 2 As shown), recorded as sample 2;

[0068] Step 3: The active transition alumina prepared in step 2 and 120 mg of urea were ultrasonically dispersed in a mixture of 20 mL of methanol and 10 mL of deionized water. A mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:12 was added and fully ultrasonically dispersed. The mixture was transferred to a 190°C autoclave for hydrothermal reaction for 15 hours. The precipitate was washed three times with ethanol and centrifuged to dry. The dried product was then placed in a tubular furnace and calcined at 550°C in an air atmosphere at a heating rate of 1°C / min for 1 hour. At this time, relatively pure aluminum silicate nanoflower particles (such as Figure 7 as shown), recorded as sample 7.

[0069] Example 5: This example provides a method for preparing aluminum silicate nanoflowers, comprising the following steps:

[0070] Step 1: 2875 mg of aluminum nitrate nonahydrate, 1000 mg of trimesic acid, and 6375 mg of polyvinyl pyrrolidone were dissolved in a mixture of 93.75 mL of ethanol, 93.75 mL of acetone, 12.5 mL of 32.5% nitric acid, and 37.5 mL of water, and the mixture was fully ultrasonically dispersed. The mixture was transferred to a Teflon-lined reactor and hydrothermally precipitated at 150°C for 45 hours to obtain a relatively dense precipitate. The precipitate was washed three times with ethanol and centrifuged to dry at 95°C. The dried product was observed under a scanning electron microscope to be bipyramidal solid nanoparticles (such as Figure 1 As shown), recorded as sample 1;

[0071] Step 2: 40 mg of bipyramidal nanoparticles were placed in a tube furnace and calcined at 500 °C in air atmosphere at a heating rate of 1 °C / min for 1 h to obtain active transition state alumina. The bipyramidal hollow nanoparticles (such as Figure 2 As shown), recorded as sample 2;

[0072] Step 3: The active transition alumina prepared in step 2 and 120 mg of urea were ultrasonically dispersed in a mixture of 20 mL of methanol and 10 mL of deionized water. A mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:10 was added and fully ultrasonically dispersed. The mixture was transferred to a 175°C autoclave for hydrothermal reaction for 15 hours. The precipitate was washed three times with ethanol and centrifuged to dry. The dried product was then placed in a tubular furnace and calcined at 550°C in an air atmosphere at a heating rate of 1°C / min for 1 hour. At this time, relatively pure aluminum silicate nanoflower particles (such as Figure 8 as shown), recorded as sample 8.

[0073] Example 6: This example provides a method for preparing aluminum silicate nanoflowers, comprising the following steps:

[0074] Step 1: 2875 mg of aluminum nitrate nonahydrate, 1000 mg of trimesic acid, and 6375 mg of polyvinyl pyrrolidone were dissolved in a mixture of 93.75 mL of ethanol, 93.75 mL of acetone, 12.5 mL of 32.5% nitric acid, and 37.5 mL of water, and the mixture was fully ultrasonically dispersed. The mixture was transferred to a Teflon-lined reactor and hydrothermally precipitated at 150°C for 45 hours to obtain a relatively dense precipitate. The precipitate was washed three times with ethanol and centrifuged to dry at 95°C. The dried product was observed under a scanning electron microscope to be bipyramidal solid nanoparticles (such as Figure 1 As shown), recorded as sample 1;

[0075] Step 2: 40 mg of bipyramidal nanoparticles were placed in a tube furnace and calcined at 500 °C in air atmosphere at a heating rate of 1 °C / min for 1 h to obtain active transition state alumina. The bipyramidal hollow nanoparticles (such as Figure 2 As shown), recorded as sample 2;

[0076] Step 3: The active transition alumina prepared in step 2 and 120 mg of urea were ultrasonically dispersed in a mixture of 20 mL of methanol and 10 mL of deionized water, and a mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:10 was added and fully ultrasonically dispersed. The mixture was transferred to a 200°C autoclave for hydrothermal reaction for 15 hours. The precipitate was washed three times with ethanol and centrifuged to dry. The dried product was then placed in a tubular furnace and calcined at 550°C in an air atmosphere at a heating rate of 1°C / min for 1 hour. At this time, relatively pure aluminum silicate nanoflower particles (such as Figure 9 as shown), recorded as sample 9.

[0077] Comparative Example 1: In this comparative example, the temperature of the Teflon-lined reactor in step 1 is adjusted to 75°C. The difference from Example 1 is that the temperature of the Teflon-lined reactor in step 1 is too low. The other steps and conditions remain unchanged. The product after completing step 1 is recorded as sample 10. Figure 10 , the product after completing step 3 is recorded as sample 11, as Figure 11 .

[0078] like Figure 4 The shape of sample 10 prepared in this comparative example observed under a scanning electron microscope was long strips or aggregated into clumps, which was inconsistent with the shape of sample 1; the product of sample 11 prepared in this comparative example observed under a scanning electron microscope did not unfold into a flower and did not form obvious petals.

[0079] The results show that when the temperature in the Teflon-lined reactor in step 1 is too low, bipyramidal nanoparticles cannot be formed after step 1 is completed, and aluminum silicate nanoflowers cannot be formed after step 3 is completed. Therefore, aluminum silicate nanoparticles cannot be produced when the temperature is too low.

[0080] Comparative Example 2: In this comparative example, the temperature of the Teflon-lined reactor in step 1 is adjusted to 225°C. The difference from Example 1 is that the temperature of the Teflon-lined reactor in step 1 is too high. The other steps and conditions remain unchanged. The product after completing step 1 is recorded as sample 12. Figure 12 , the product after completing step 3 is recorded as sample 13, as shown in Figure 13 .

[0081] like Figure 12 The shape of sample 12 prepared in this comparative example observed under a scanning electron microscope was long and narrow or aggregated, which was inconsistent with the shape of sample 1; the product of sample 13 prepared in this comparative example observed under a scanning electron microscope did not unfold into a flower and did not form obvious petals.

[0082] The results show that when the temperature in the Teflon-lined reactor in step 1 is too high, bipyramidal nanoparticles cannot be formed after step 1 is executed, and aluminum silicate nanoflowers cannot be formed after step 3 is executed. Therefore, aluminum silicate nanoflowers cannot be produced when the temperature is too high.

[0083] Comparative Example 3: In this comparative example, the calcination temperature is adjusted to 400°C in step 2, and the heating rate remains unchanged. The difference from Example 1 is that the calcination temperature in step 2 is adjusted too low, and the other steps and conditions remain unchanged. The product prepared after executing step 2 is recorded as sample 14. Figure 14 The product prepared after step 3 is recorded as sample 15. Figure 15 .

[0084] like Figure 8As shown, the transparency of the nanoparticles of sample 14 prepared in this comparative example observed under a scanning electron microscope is not as good as that of sample 2, proving that active transition alumina has not yet been prepared. The petals formed by the product of sample 15 prepared in this comparative example observed under a scanning electron microscope are incomplete.

[0085] The results show that when the calcination temperature in step 2 is too low, active transition alumina cannot be formed after step 2 is completed, and aluminum silicate nanoflowers cannot be formed after step 3 is completed. Therefore, when the temperature is too low, aluminum silicate nanoflowers cannot be produced.

[0086] Comparative Example 4: In this comparative example, the calcination temperature is adjusted to 750°C in step 2, and the heating rate remains unchanged. The difference from Example 1 is that the calcination temperature in step 2 is adjusted too high, and the other steps and conditions remain unchanged. The product prepared after executing step 2 is recorded as sample 16. Figure 16 The product prepared after step 3 is recorded as sample 17. Figure 17 .

[0087] like Figure 10 As shown, the nanoparticles of sample 16 prepared in this comparative example formed compact Al2O3 when observed under a scanning electron microscope, proving that active transition alumina has not yet been prepared. The petals of the product formed by sample 17 prepared in this comparative example observed under a scanning electron microscope were incompletely unfolded.

[0088] The results show that when the calcination temperature in step 2 is too high, active transition alumina cannot be formed after step 2 is completed, and aluminum silicate nanoflowers cannot be formed after step 3 is completed. Therefore, when the temperature is too high, aluminum silicate nanoflowers cannot be produced.

[0089] Comparative Example 5: This comparative example does not add urea in step 3. The difference from Example 1 is that urea is not added in step 3. Other steps and conditions remain unchanged. The product prepared after step 3 is recorded as sample 18. Figure 18 .

[0090] like Figure 18 As shown, no fully expanded aluminum silicate nanoflowers were observed in the sample 18 prepared in this comparative example under a scanning electron microscope.

[0091] The results showed that when urea was not added in step 3, fully expanded aluminum silicate nanoflowers could not be formed after all steps were completed, proving that urea is an indispensable factor in the preparation of aluminum silicate nanoflowers.

[0092] Comparative Example 6: In this comparative example, a mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:1 is added in step 3 and fully ultrasonically dispersed. The difference from Example 1 is that the content of tetraethyl orthosilicate in step 3 is increased, that is, the silicon content in the mixed solution is increased. Other conditions and steps remain unchanged. The product prepared after executing step 3 is recorded as sample 19. Figure 19 .

[0093] like Figure 19 As shown, under an electron microscope, no aluminum silicate nanoflowers were observed in sample 19 prepared in this comparative example, but many silicon balls were formed instead.

[0094] The results show that when the content of tetraethyl orthosilicate in step 3 is too high, complete aluminum silicate nanoflowers cannot be formed after all steps are completed.

[0095] Comparative Example 7: In this comparative example, a mixed solution of tetraethyl orthosilicate and methanol in a mixing ratio of 1:20 is added in step 3 and fully ultrasonically dispersed. The difference from Example 1 is that the content of tetraethyl orthosilicate in step 3 is reduced, that is, the content of silicon in the mixed solution is reduced. Other conditions and steps remain unchanged. The product prepared after executing step 3 is recorded as sample 20. Figure 20 .

[0096] like Figure 20 As shown, the sample 20 prepared in this comparative example was observed to be flaky nanoflowers under a scanning electron microscope, and no formed aluminum silicate nanoflowers appeared.

[0097] The results show that when the content of tetraethyl orthosilicate in step 3 is too low, complete aluminum silicate nanoflowers cannot be formed after all steps are completed.

[0098] Comparative Example 8: In this comparative example, the temperature of the hydrothermal reaction in the autoclave in step 3 is adjusted to 150°C. The difference from Example 1 is that the temperature of the hydrothermal reaction in the autoclave in step 3 is adjusted to a lower temperature. The other steps and conditions remain unchanged. The product prepared after executing step 3 is recorded as sample 21. Figure 21 .

[0099] like Figure 21 , the sample 21 prepared in this comparative example was observed to have incompletely unfolded nanoflowers under a scanning electron microscope, and no formed nanoflowers appeared.

[0100] The results show that when the temperature of the hydrothermal reaction in the autoclave in step 3 is too low, complete aluminum silicate nanoflowers cannot be formed after all steps are completed, that is, the temperature of the hydrothermal reaction in the autoclave is an important factor affecting the preparation.

[0101] Comparative Example 9: In this comparative example, the temperature of the hydrothermal reaction in the autoclave in step 3 is adjusted to 250°C. The difference from Example 1 is that the temperature of the hydrothermal reaction in the autoclave in step 3 is adjusted to a higher temperature. The other steps and conditions remain unchanged. The product prepared after executing step 3 is recorded as sample 22. Figure 22 .

[0102] like Figure 22 Under a scanning electron microscope, the sample 22 prepared in this comparative example showed over-expanded nanoflowers, whose petals had been destroyed by high temperature and no formed nanoflowers appeared.

[0103] The results show that when the temperature of the hydrothermal reaction in the autoclave in step 3 is too high, complete aluminum silicate nanoflowers cannot be formed after all steps are completed, that is, the temperature of the hydrothermal reaction in the autoclave is an important factor affecting the preparation.

[0104] The specific surface area and pore size distribution of samples 1 to 22 in each embodiment and comparative example were tested and compared using an IW-BK100 specific surface area analyzer (manufactured by Beijing Jingwei Gaobo Science and Technology Co., Ltd.). The specific surface area and pore size distribution of each sample were examined. The results are shown in Table 1.

[0105]

[0106] The results show that the preparation process of aluminum silicate nanoflowers of this invention is real and effective, and the accurate and effective preparation method can successfully prepare aluminum silicate nanoflowers, proving that temperature, whether to add urea and the proportion of TEOS are all important influencing conditions that affect whether aluminum silicate nanoflowers can be finally prepared.

[0107] In summary, the results demonstrate that the proposed aluminum silicate nanoflower preparation process is effective. Comparative Examples 1-9 demonstrate that temperature, the presence of urea, and the TEOS ratio are all key factors influencing the final production of aluminum silicate nanoflowers.

[0108] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned embodiments. The description of the embodiments is for the convenience of ordinary technicians in this technical field to understand and use the invention. It is obvious that those familiar with the technology in this field can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to go through creative work. Therefore, the present invention is not limited to the above-mentioned embodiments. 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 present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum silicate-based nanoflower porous material, characterized in that: Step 1: A water-soluble aluminum salt, benzoic acid, and polyvinyl pyrrolidone are dissolved in solvent A, followed by a hydrothermal reaction. The resulting precipitate is washed and dried to obtain aluminum-containing bipyramidal organic metal nanoparticles; the solvent A comprises ethanol, acetone, nitric acid, and water; the hydrothermal reaction temperature in step 1 is 140-160° C., and the reaction time is 40-50 h. Step 2: The product obtained in step 1 is placed in a tube furnace for calcination to obtain an aluminum-containing organic metal framework; the calcination temperature is 440-550° C., the time is 1-2 hours, and the calcination environment is air; Step 3: Add the product obtained in step 2 and urea to solvent B and mix them evenly, then add organosilicate and carry out a hydrothermal reaction; the obtained product is washed, dried, and calcined to obtain aluminum silicate nanoflowers; the solvent B is composed of methanol and water; the mass ratio of organosilicate to solvent B in step 3 is 1:8~12; the reaction temperature of the hydrothermal reaction in step 3 is 160~220℃, and the reaction time is 14~16 hours.

2. The method for preparing an aluminum silicate-based nanoflower porous material according to claim 1, wherein: In step 1, the water-soluble aluminum salt is selected from at least one of aluminum nitrate, aluminum sulfate, aluminum acetate, aluminum oxalate, and aluminum chloride; In step 1, the benzoic acid is selected from at least one of trimesic acid, p-benzoic acid, o-benzoic acid, and m-benzoic acid.

3. The method for preparing an aluminum silicate-based nanoflower porous material according to claim 2, wherein: The aluminum nitrate is aluminum nitrate nonahydrate. In step 1, the mass ratio of trimesic acid, aluminum nitrate nonahydrate, and polyvinyl pyrrolidone is 1:2-4:6-8. The volume ratio of nitric acid with a volume concentration of 32.5%, water, ethanol, and acetone is 1:2-4:7-9:7-9.

4. The method for preparing an aluminum silicate-based nanoflower porous material according to claim 1, wherein: The drying temperature in step 1 is 90-100°C.

5. The method for preparing an aluminum silicate-based nanoflower porous material according to claim 1, wherein: In step 3, urea is added to solvent B, and the mass ratio of urea to solvent B is 1:200-:

300.

6. The method for preparing an aluminum silicate-based nanoflower porous material according to claim 1, characterized in that: In step 3, the calcination temperature is 525-575° C., the calcination time is 30-12 minutes, and the calcination atmosphere is an oxygen-containing atmosphere.

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