Preparation method of sodium aluminosilicate microspheres

Abstract

The present invention discloses a preparation method of sodium aluminosilicate microspheres. The preparation method uses sodium aluminate and tetraethyl orthosilicate as raw materials through a solvothermal method to synthesize sodium aluminosilicate microspheres under alkaline conditions. The present invention provides a preparation method of sodium aluminosilicate microspheres with low density, low thermal conductivity, and good chemical stability. It has been improved on the traditional production method, and sodium aluminosilicate hollow microspheres are directly synthesized by a one-step method, simplifying the production process of silicate hollow microspheres, enabling sodium aluminate and tetraethyl orthosilicate to directly react under appropriate conditions, reducing the production time, improving the production efficiency, shortening the actual production cycle, and showing great application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of building thermal insulation materials, and particularly relates to a method for preparing sodium aluminum silicate microspheres. Background Art

[0002] With the vigorous development of science and technology, people's demand for energy is gradually increasing. However, what people are facing is the increasing depletion of energy and increasingly serious environmental problems. Therefore, how to use resources more efficiently, save resources, and protect resources has become the focus of attention of all countries. Building energy consumption accounts for 30%-40% of the total energy consumption, and most of it is energy consumption for air conditioning and heating. How to effectively reduce energy consumption has become the focus of attention of all countries.

[0003] Thermal insulation coatings are applied on the surface of buildings, and one or more methods such as blocking, reflection, and radiation are used to keep the temperature in the house within a comfortable temperature range, reduce the energy consumption of air conditioning and heating, and achieve energy saving. At present, there are some problems with the coatings on the market, such as poor fire resistance, non-standard construction, harsh construction conditions, and insufficient bonding strength of composite silicate thermal insulation coatings. Compared with other materials, hollow microspheres have low density and light weight compared with traditional materials, which greatly reduces the convenience of construction; and the hollow microspheres have large cavities inside, so the thermal conductivity is very low and the fire resistance is very good; and the hollow microspheres have good fluidity, so the bonding strength is very high. Therefore, the thermal insulation coating using hollow microspheres as fillers has excellent thermal insulation performance. However, the cycle required to prepare hollow microspheres is relatively long, which increases the time cost of production. Summary of the invention

[0004] The present invention is proposed to overcome the disadvantage of the prior art that the preparation of hollow microspheres requires a long period of time, and its purpose is to provide a method for preparing sodium aluminum silicate microspheres.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing sodium aluminum silicate microspheres comprises the following steps:

[0007] (i) adding a silicon source and a soft template into a first solvent and stirring to obtain a solution A; adding an aluminum source into a second solvent and stirring to obtain a solution B;

[0008] (ii) slowly adding solution B into solution A, adding an alkali source thereto while adding solution B, adjusting the pH of the solution to between 11 and 12, and stirring thoroughly to obtain solution C;

[0009] (ⅲ) Transfer solution C to a reaction vessel for solvothermal reaction, then take it out, filter and wash to obtain sodium aluminosilicate hollow microspheres.

[0010] In the above technical solution, the silicon source is tetraethyl orthosilicate; the aluminum source is sodium aluminate; the soft template agent is cetyltrimethylammonium bromide; the first solvent is an ethanol solution; the second solvent is deionized water.

[0011] In the above technical solution, the stirring time of solution A and solution B in step (ⅰ) and the stirring time in step (ⅱ) are both 30 min.

[0012] In the above technical solution, in step (ⅱ), solution B and solution A are mixed according to a molar ratio of silicon source to aluminum source of 1:1.

[0013] In the above technical solution, the base source is an ammonia water solution; the concentration of the ammonia water solution is 1 mol / L.

[0014] In the above technical solution, in solution A of step (ⅰ), the concentration of the silicon source is 0.3 mol / L to 0.4 mol / L, and the concentration of the soft template agent in solution A is 0.08 mol / L to 0.10 mol / L; the concentration of the aluminum source in solution B is 0.25 mol / L to 0.30 mol / L. Preferably, in step (ⅰ), the addition amount of tetraethyl orthosilicate as the silicon source is 0.367 mol / L, the addition amount of sodium aluminate as the aluminum source is 0.275 mol / L, and the addition amount of cetyltrimethylammonium bromide as the soft template agent is 0.09 mol / L.

[0015] In the above technical solution, the conditions for the hydrothermal reaction in step (ⅲ) are: heating to 150 °C in an oven and keeping warm for 0.5 h to 18 h.

[0016] A sodium aluminosilicate microsphere is a hollow microsphere, and the particle size of the hollow microsphere is 2.05 ± 0.19 μm, and the wall thickness is 173 ± 40 nm.

[0017] The beneficial effects of the present invention are:

[0018] The present invention provides a preparation method of sodium aluminosilicate microspheres with low density, low thermal conductivity and good chemical stability. It is improved on the traditional production method, and sodium aluminosilicate hollow microspheres are directly synthesized by a one-step method, which simplifies the production process of silicate hollow microspheres, enables sodium aluminate and tetraethyl orthosilicate to directly react under appropriate conditions, reduces the production time, improves the production efficiency, shortens the actual production cycle, and shows great application prospects; the prepared hollow microspheres have good heat preservation performance, heavy metal ion and organic pollutant adsorption capabilities, and can become a kind of heat preservation material that can be designed. Description of the Drawings

[0019] Figure 1 XRD patterns of the sodium aluminosilicate hollow microsphere material of Example 5 of the present invention before calcination and after being treated at different calcination temperatures;

[0020] Figure 2 SEM photos of the sodium aluminosilicate hollow microsphere material of the polyetheretherketone / tobermorite whisker composite material of Examples 1 to 5 of the present invention;

[0021] Figure 3 TEM photo of the sodium aluminosilicate hollow microsphere material of Example 5 of the present invention;

[0022] Figure 4 FT-IR data of the sodium aluminosilicate hollow microsphere material of Example 5 of the present invention after calcination;

[0023] For those of ordinary skill in the art, without creative efforts, other relevant drawings can be obtained based on the above drawings. Detailed implementation manners

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the drawings in the specification and through specific implementation manners.

[0025] Example 1

[0026] A preparation method of sodium aluminosilicate hollow microspheres specifically includes the following steps:

[0027] (ⅰ) Tetraethyl orthosilicate and cetyltrimethylammonium bromide are added to anhydrous ethanol to obtain solution A, so that the concentration of tetraethyl orthosilicate is 0.367 mol / L and the concentration of cetyltrimethylammonium bromide is 0.09 mol / L. Sodium aluminate is added to deionized water to prepare solution B, so that the concentration of sodium aluminate is 0.275 mol / L. Solutions A and B are each stirred for 30 min;

[0028] (ⅱ) According to the molar ratio of tetraethyl orthosilicate:sodium aluminate of 1:1, solution B is slowly added to solution A and mixed and stirred. While adding solution B, an appropriate amount of ammonia water solution is added to adjust the pH value of the solution between 11 and 12, and stirred for 30 min to obtain solution C;

[0029] (ⅲ) Solution C is transferred to a reaction kettle, and the reaction kettle is placed in a vacuum drying oven. The temperature is raised to 150 °C in the vacuum drying oven, kept warm for 0.5 h, taken out, and filtered and washed to obtain sodium aluminosilicate hollow microspheres.

[0030] Example 2

[0031] A preparation method of sodium aluminosilicate hollow microspheres, specifically including the following steps:

[0032] (ⅰ) Add tetraethyl orthosilicate and cetyltrimethylammonium bromide to anhydrous ethanol to obtain solution A, with the concentration of tetraethyl orthosilicate being 0.367 mol / L and the concentration of cetyltrimethylammonium bromide being 0.09 mol / L. Add sodium aluminate to deionized water to prepare solution B, with the concentration of sodium aluminate being 0.275 mol / L. Stir solution A and solution B for 30 min respectively;

[0033] (ⅱ) According to the molar ratio of tetraethyl orthosilicate:sodium aluminate being 1:1, slowly add solution B to solution A and mix and stir. While adding solution B, add an appropriate amount of ammonia water solution to adjust the pH value of the solution between 11 and 12, and stir for 30 min to obtain solution C;

[0034] (ⅲ) Transfer solution C to a reaction kettle, place the reaction kettle in a vacuum drying oven, heat up to 150 °C in the vacuum drying oven, keep warm for 3 h, take out, filter and wash to obtain sodium aluminosilicate hollow microspheres.

[0035] Example 3

[0036] A preparation method of sodium aluminosilicate hollow microspheres, specifically including the following steps:

[0037] (ⅰ) Add tetraethyl orthosilicate and cetyltrimethylammonium bromide to anhydrous ethanol to obtain solution A, with the concentration of tetraethyl orthosilicate being 0.367 mol / L and the concentration of cetyltrimethylammonium bromide being 0.09 mol / L. Add sodium aluminate to deionized water to prepare solution B, with the concentration of sodium aluminate being 0.275 mol / L. Stir solution A and solution B for 30 min respectively;

[0038] (ⅱ) According to the molar ratio of tetraethyl orthosilicate:sodium aluminate being 1:1, slowly add solution B to solution A and mix and stir. While adding solution B, add an appropriate amount of ammonia water solution to adjust the pH value of the solution between 11 and 12, and stir for 30 min to obtain solution C;

[0039] (ⅲ) Transfer solution C to a reaction kettle, place the reaction kettle in a vacuum drying oven, heat up to 150 °C in the vacuum drying oven, keep warm for 6 h, take out, filter and wash to obtain sodium aluminosilicate hollow microspheres.

[0040] Example 4

[0041] A preparation method of sodium aluminosilicate hollow microspheres, specifically including the following steps:

[0042] (i) Add tetraethyl orthosilicate and cetyltrimethylammonium bromide to absolute ethanol to obtain solution A, with the concentration of tetraethyl orthosilicate being 0.367 mol / L and the concentration of cetyltrimethylammonium bromide being 0.09 mol / L. Add sodium aluminate to deionized water to prepare solution B, with the concentration of sodium aluminate being 0.275 mol / L. Stir solution A and solution B for 30 min respectively;

[0043] (ii) According to the molar ratio of tetraethyl orthosilicate:sodium aluminate of 1:1, slowly add solution B to solution A and mix and stir. While adding solution B, add an appropriate amount of ammonia water solution to adjust the pH value of the solution between 11 and 12, and stir for 30 min to obtain solution C;

[0044] (iii) Transfer solution C to a reaction kettle, place the reaction kettle in a vacuum drying oven, heat it to 150 °C in the vacuum drying oven, keep it warm for 12 h, take it out, filter and wash to obtain sodium aluminosilicate hollow microspheres.

[0045] Example 5

[0046] A preparation method of sodium aluminosilicate hollow microspheres specifically includes the following steps:

[0047] (i) Add tetraethyl orthosilicate and cetyltrimethylammonium bromide to absolute ethanol to obtain solution A, with the concentration of tetraethyl orthosilicate being 0.367 mol / L and the concentration of cetyltrimethylammonium bromide being 0.09 mol / L. Add sodium aluminate to deionized water to prepare solution B, with the concentration of sodium aluminate being 0.275 mol / L. Stir solution A and solution B for 30 min respectively;

[0048] (ii) According to the molar ratio of tetraethyl orthosilicate:sodium aluminate of 1:1, slowly add solution B to solution A and mix and stir. While adding solution B, add an appropriate amount of ammonia water solution to adjust the pH value of the solution between 11 and 12, and stir for 30 min to obtain solution C;

[0049] (iii) Transfer solution C to a reaction kettle, place the reaction kettle in a vacuum drying oven, heat it to 150 °C in the vacuum drying oven, keep it warm for 18 h, take it out, filter and wash to obtain sodium aluminosilicate hollow microspheres.

[0050] Example 6

[0051] A preparation method of sodium aluminosilicate hollow microspheres specifically includes the following steps:

[0052] (ⅰ) Tetraethyl orthosilicate and cetyltrimethylammonium bromide were added to absolute ethanol to obtain solution A, with the concentration of tetraethyl orthosilicate being 0.367 mol / L and the concentration of cetyltrimethylammonium bromide being 0.09 mol / L. Sodium aluminate was added to deionized water to prepare solution B, with the concentration of sodium aluminate being 0.275 mol / L. Solution A and solution B were each stirred for 30 min;

[0053] (ⅱ) According to the molar ratio of tetraethyl orthosilicate:sodium aluminate of 1:1, solution B was slowly added to solution A and mixed with stirring. While adding solution B, an appropriate amount of ammonia water solution was added to adjust the pH value of the solution between 11 and 12, and stirred for 30 min to obtain solution C;

[0054] (ⅲ) Solution C was transferred to a reaction kettle, and the reaction kettle was placed in a vacuum drying oven. The temperature was raised to 150 °C in the vacuum drying oven and kept warm for 24 h. Then it was taken out, filtered and washed to obtain sodium aluminosilicate hollow microspheres.

[0055] XRD analysis was carried out on the sodium aluminosilicate hollow microsphere material of Example 5 of the present invention, and the test results are as Figure 1 shown. It can be Figure 1 seen that when the sodium aluminosilicate hollow microspheres were not calcined and the calcination temperature did not exceed 750 °C, the positions of the diffraction peaks did not change significantly, and no obvious new peaks appeared. This indicates that when the calcination temperature of this substance is lower than 750 °C, no crystal form transformation occurs to change the crystal state. After the substance was calcined at 850 °C, new diffraction peaks appeared. By comparing the new diffraction peaks with the standard card PDF#52-1342, it was found that they were consistent, indicating that the prepared sample was NaAlSiO4, and the 2θ angles of 21.2°, 24.5°, 29.3°, 35.0°, and 41.4° corresponded to the diffraction peaks of the (111), (121), (211), (141), and (151) crystal planes respectively. The diffraction peaks of the sodium aluminosilicate samples synthesized at different calcination temperatures were all relatively wide, indicating that the crystallinity of the synthesized sodium aluminosilicate samples was low and the grain size was small.

[0056] Only the solvothermal reaction duration was different in Examples 1 to 6 of the present invention. SEM analysis was carried out on the sodium aluminosilicate hollow microsphere materials of Examples 1 to 6 of the present invention. It can be seen that with the change of the reaction time, the morphology of the microspheres changed greatly. When the reaction time was short, the reactants did not form microspheres with a complete spherical structure, and there were still many unreacted particles remaining on the surface of the microspheres, and the shape was irregular, and there were many unreacted microspheres; as the reaction time was extended, the reaction gradually occurred completely, Figure 2C, D, E, and F all have obvious spherical structures with regular shapes and little bonding. This shows that when the reaction time is more than 6 hours, sodium aluminum silicate hollow microspheres with complete structure and regular shape can be synthesized. The above analysis shows that sodium aluminum silicate hollow microspheres with complete structure, regular shape, and good particle size distribution can be prepared by the solvothermal method under appropriate reaction conditions. Figure 2 The particle size analysis of the microspheres in groups A to F revealed that Figure 2 The average particle size of the microspheres in C, D, E, and F is between 2 and 3 μm, and the particle size uniformity of the microspheres in Figure E is the best.

[0057] The sodium aluminum silicate hollow microsphere material of Example 5 of the present invention was subjected to TEM and BET analysis. The test results are as follows: Figure 3 As shown. Figure 3 Different contrast observations show that the microspheres are hollow inside, indicating that the prepared microspheres have hollow microspheres. The hollow microspheres are uniformly spherical in shape, with uniformly distributed shells. Through the analysis of the particle size analysis software after TEM testing, it was found that the wall thickness of the synthesized microspheres is approximately 173±40nm.

[0058] The hollow microsphere material of sodium aluminum silicate in Example 5 of the present invention was subjected to FT-IR analysis. The test results are as follows: Figure 4 shown. Figure 4 From bottom to top, the FR-IR images of uncalcined sodium aluminum silicate hollow microspheres and sodium aluminum silicate hollow microspheres calcined at different temperatures are shown. -1 There are three peaks at 1000cm-1, which are the characteristic peaks of CTAB. By comparing the graphs before and after calcination, it can be seen that when the calcination temperature is above 550℃, the three peaks in this frequency band disappear, indicating that the CTAB on the surface of the microspheres has been removed. -1 A broad absorption peak appears at 700 cm -1 There is an obvious absorption peak at the position, which is caused by the symmetrical stretching vibration of the Al-O bond, indicating that there are a large number of aluminum ions in it.

[0059] The reaction mechanism involved in the present invention is as follows:

[0060] Si(OC2H5)+4H2O→Si(OH)4+4C2H5OH (1)

[0061] SI(OH)4+NaAlO2→NaAlSiO4+2H2O (2)

[0062] Among the raw materials used in the present invention, tetraethyl orthosilicate can provide the silicon and oxygen elements required for forming hollow microspheres, and sodium aluminate can provide the aluminum and sodium elements required for forming hollow microspheres; cetyltrimethylammonium bromide, as a surfactant with an amphiphilic structure, can be used as a soft template for preparing hollow microspheres; ammonia water can adjust the pH and promote the hydrolysis of reactants; deionized water and absolute ethanol act as solvents in the reaction.

[0063] The present invention controls the addition order of reaction raw materials and adopts the order of slowly adding solvent B to solvent A. If solution A is added to solution B, the solution will become turbid instantly during mixing, which cannot meet the requirements of the product we want to synthesize; meanwhile, the present invention adopts a dual-solvent system, and the solvent cannot be simply dissolved in water or ethanol because CTAB is slightly soluble in water and can only be fully dissolved in ethanol; sodium aluminate is insoluble in ethanol and can only be fully dissolved in water. A single solvent cannot be used to synthesize hollow microspheres.

[0064] The present invention directly synthesizes sodium aluminosilicate hollow microspheres by a one-step method, simplifies the production process of silicate hollow microspheres, enables sodium aluminate and tetraethyl orthosilicate to react directly under appropriate conditions, reduces the production time, adopts a dual-solvent system, and mixing the template agent with the silicon source of the framework material first is beneficial to controlling the product morphology and forming a hollow microsphere structure.

[0065] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0066] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing sodium aluminosilicate microspheres, characterized in that: It includes the following steps: (ⅰ) Add a silicon source and a soft template agent to a first solvent, and stir to obtain solution A; add an aluminum source to a second solvent, and stir to obtain solution B; The silicon source is tetraethyl orthosilicate; the aluminum source is sodium aluminate; the soft template agent is cetyltrimethylammonium bromide; the first solvent is absolute ethanol; the second solvent is deionized water; The concentration of the silicon source in solution A is 0.3 mol / L to 0.4 mol / L, and the concentration of the soft template agent in solution A is 0.08 mol / L to 0.10 mol / L; the concentration of the aluminum source in solution B is 0.25 mol / L to 0.30 mol / L; (ⅱ) Add solution B and an alkali source to solution A, and stir thoroughly to obtain solution C; Solution B and solution A are mixed according to a molar ratio of the silicon source to the aluminum source of 1:1; (ⅲ) Transfer solution C to a reaction vessel for solvothermal reaction. After the reaction is completed, filter and wash to obtain sodium aluminosilicate hollow microspheres; The conditions of the solvothermal reaction are: heat up to 150 °C in an oven and keep warm for 0.5 h to 18 h.

2. The preparation method of the sodium aluminosilicate microspheres according to claim 1, characterized in that: The stirring time of solution A and solution B in step (ⅰ) and the stirring time in step (ⅱ) are both 30 min.

3. The preparation method of the sodium aluminosilicate microspheres according to claim 1, characterized in that: The alkali source is an ammonia water solution; the concentration of the ammonia water solution is 1 mol / L.

4. The preparation method of the sodium aluminosilicate microspheres according to claim 1, characterized in that: After adding the alkali source in step (ⅱ), adjust the pH of solution C to be between 11 and 12.

5. A sodium aluminosilicate microsphere, characterized in that: Prepared by the method according to any one of claims 1 to 4.

6. The sodium aluminosilicate microspheres according to claim 5, characterized in that: The sodium aluminosilicate microspheres are hollow microspheres, and the particle size of the hollow microspheres is 2.05 ± 0.19 μm, and the wall thickness is 173 ± 40 nm.

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